Chemoprevention of Colon Carcinogenesis by Dietary Curcumin, a Naturally Occurring Plant Phenolic Compound'

[CANCER RESEARCH55, 259-266, January 15, 1995] Chemoprevention of Colon Carcinogenesis by Dietary Curcumin, a Naturally Occurring Plant Phenolic Compound'

Chinthalapally V. Rao, Abraham Rivenson, Barbara Simi, and Bandaru S. Redd?

Divisions ofNutritional Carcinogenesis (C. V. R., B. S., B. S. R.J Pathology [A. RI, American Health Foundation, Valhalla, New York 10595

ABSTRACT factors may not always be possible; however, as an alternative ap proach, the agents for alleviating the carcinogenic effect of several of Human epidemiological and laboratory animal model studies have these substances have been identified and tested for their chemopre suggested that nonsteroidal antlinflammatory drugs reduce the risk of development of colon cancer and that the inhibition of colon carcinogen ventive action (5). Wattenberg (5), Boone et a!. (6), and Kelloff et a!. esis is mediated through the alteration in cyclooxygenase metabolism of (7) reviewed the results of many chemoprevention studies in arachidonic acid. Curcumin, whichis a naturally occurring compound,is laboratory animal models and in a human setting. present in turmeric, possesses both antiinflammatory and antioxidant Although the use of medicinal plants or their active principles in the properties, and has been tested for its chemopreventive properties in skin prevention and/or treatment of chronic diseases is based on the expe and forestomach carcinogenesis. The present study was designed to inves rience of traditional systems of medicine from different ethnic soci ligate the chemopreventive action of dietary curcumin on azoxymethane eties, their use in modem medicine suffers from lack of scientific induced colon carcinogenesis and also the modulating effect of this agent evidence. Only very few medicinal plants have attracted the interest of on the colonic mucosal and tumor phospholipase A2, phosphoilpase Cyl, scientists, and one such plant is Curcuma longa Linn. The powdered lipoxygenase, and cydooxygenase activities in male F344 rats@ At S weeks of age, groups of animals were fed the control (modified AIN-76A) diet or rhizome of this plant, turmeric, has been extensively used for impart a diet containing 2000 ppm of curcumin. At 7 weeks of age, all animals, ing color and flavor to foods and also for the treatment of variety of except those in the vehide (normal sallne)-treated groups, were given two inflammatory conditions and other diseases (8, 9). Curcumin (diferu weekly s.c. injections of azoxymethane at a dose rate of 15 mglkg body loylmethane), a phenolic compound (Fig. 1) that has been identified as weighL All groups were continued on their respective dietary regimen the major pigment in turmeric, possesses both antiinflamatory until the termination of the experiment at 52 weeks after the carcinogen (10â€”12)and antioxidant properties (13, 14). treatment Colonic tumors were evaluated hlstopathologically Colonic Previous studies have shown that topical application of curcumin mucosa and tumors were analyzed for phospholipase A2, phospholipase inhibits TPA3-induced epidermal DNA synthesis, tumor promotion Cl!, CXVlVOprostaglandin (PG) E2, cyclooxygenase, and ilpoxygenase activitieS.The results indicate that dietary administration of curcumin in mouse skin, and edema of mouse ears (15, 16). Topical appli significantly inhibited incidence ofcolon adenocarcinomas (P < 0.004) and cation of curcumin also inhibited B(a)-induced DNA adducts and the multiplicity of invasive (P < 0.015), noninvasive (P < 0.01), and total skin tumors as well as DMBA-induced skin tumors (17). In other (invasive plus noninvasive) adenocarcinomas (P < 0.001). Dietary curcu studies, dietary administration of 2% turmeric in the diet inhibited mm also significantly suppressed the colon tumor volume by >57% corn the DMBA-induced skin, B(a)P-induced forestomach, and AOM pared to the control diet Animals fed the curcumin diet showed decreased induced small and large intestinal tumors in mice (18, 19). In most activities of colonic mucosal and tumor phosphoilpase A2 (50%) and of these studies, curcumin purity was less than or about 85%. phospholipase Cyl (40%) and levels of PGE2 (>38%). The formation of Earlier studies from our laboratory had shown that 2000 ppm prostaglandins such as PGE@, PGF@, PGD2, 6-keto PGF1@, and thrum boxane B2 through the cyclooxygenase system and production of 5(S)-, curcumin (>98% pure) in the diet significantly suppressed the 8(5)-, 12(5)-, and 15(S)-hydroxyeicosatetraenoic acids via the lipoxygen AOM-induced colonic aberrant crypt foci formation, which are ase pathway from arachidonic acid were reduced in colonic mucosa and early preneoplastic lesions, in male F344 rats (20). tumors of animals fed the curcumin diet as compared to control diet. The biosynthesis of PGs through the COX system and of hydroxy Although the precise mechanism by which curcumin Inhibits colon to fatty acids via LOX pathway from AA has been well documented. morigenesis remains to be elucidated, it is likely that the chernopreventive These metabolites of AA exert a variety of biological activities. action, at least in part, may be related to the modulation of arachidonic Several studies have shown that COX metabolites, particularly PGs of add metabolism. the type-2 series modulate cell proliferation, tumor growth, and im mune responses (21, 22), whereas LOX metabolites can influence INTRODUCTION various biological responses including chemotoxic responses, hor Large bowel cancer is the leading neoplastic disease that strikes mone secretion, ion transport, tumor cell adhesion, stimulation of men and women in high frequency in Western countries including tumor cell spreading, and regulation of tumor cell metastatic potential North America (1, 2). Although several epidemiological and experi (23â€”25).The generation of AA for biosynthesis of COX and LOX mental studies suggest a relationship between colon cancer risk and metabolites involves degradation of phosphatidylinositol via a se dietary factors, its etiology is multifactorial and complex in that it may quence of reactions regulated by PLC (22, 26). The second pathway arise from the combined action of environmental factors such as low in the generation of AA involves a direct action of a PLA2 on a levels of an assortment of, as yet unidentified, genotoxic agents, phospholipid (22, 27). There are several forms of PLC and PLA2, dietary factors, and endogenous formation of tumorigenic substances among them PLOy!, a membrane-bound PIP2 specific form, and (1â€”4). Prevention strategies for cancer control involving complete cytosolic PLA2, implicated in regulation of eicosanoid biosynthesis reduction or elimination of human exposure to these environmental and cell proliferation (27, 28). In several studies, increased levels of PLA2 and PLCyl activities were observed in human colon and breast

Received 7/25/94; accepted 11/10/94. The costs of publication of this article were defrayed in part by the payment of page 3 The abbreviations used are: TPA, 12-O-tetradecanoylphorbol-13-acctate; B(a)P, charges. This article must therefore be hereby marked advertisement in accordance with benzo(a)pyrene; DMBA, 7,12-dimethylbenz[ajanthracene; AOM, azoxymethane; COX, 18 U.S.C. Section 1734 solely to indicate this fact. cyclooxygenase; LOX, lipoxygenase; POx, prostaglandins; AA, arachidonic acid; PLA2, 1 Supported by USPHS Grant CA 17613 awarded by the National Cancer Institute. phospholipase A2; PLC-yl, phopholipase C'yl; PAPC, L-a-1-palmitoyl-2-arachidonyl 2 To whom requests for reprints should be addressed, at Division of Nutritional phosphatidylcholine; HETEs, hydroxyeicosatetraenoic acids; Tx, thromboxane; PIP2, Carcinogenesis, One Dana Road, American Health Foundation, Valhalla, NY 10595. L-3-phosphatidylinositol 4,5-biphosphate. 259

Animals and Diets ,OCH3 H3CO Weaning male F344 rats were purchased from Charles River Breeding Laboratories (Kingston, NY). All ingredients of the semipurifled diet were obtained from Dyets, Inc. (Bethlehem, PA) and were stored at 4Â°Cpriorto the HO preparation of diets. Male P344 rats received at weanling were quarantined for 10 days and had access to modified AIN-76A control diet (36). Following quarantine, all the animals were randomly distributed by weight into various CU RC UN IN groups and transferred to an animal holding room. They were housed in plastic Fig. 1. Structure of diferuloylmethane (curcumin). cageswith filter tops (threeper cage)undercontrolledconditionsof a 12-h light/12-h dark cycle, 50% humidity, and 21Â°Ctemperature. The experimental diet was prepared by adding curcumin to the control diet at the expense of dextrose. The incorporation of curcumin into the control diet was done with tumors and melanomas compared to normal tissues (29â€”31).In this V-blenderafter curcumin was premixed with a small quantity of diet in a food regard, it is noteworthy that the COX metabolite, PGE@,which sig mixer to ensure its uniform distribution. All control and experimental diets nificantly affects tumor growth and immune responses, has been were prepared weekly in our laboratory and stored in a cold room. Animals had found at high levels in experimental animal tumors as well as in access to food and water at all times, and food cups were replenished with fresh human tumors (21, 32, 33). We and others have shown that COX diet three times weekly. inhibitors such as aspirin, indomethacin, piroxicam, sulindac, and The purity and stability ofcurcumin was analyzed by HPLC. Curcumin was ibuprofen suppress colon carcinogenesis in laboratory animal models extracted from the diet with 2 volumes of acetonitrile:acetic acid (95:5). The (21, 33â€”35).Thus, the possibility exists that the changes in the organic layer was dried and redissolved in a mobile phase containing 0.1 M activities of PLA2 and PLC'yl, which are involved in signal transduc sodium phosphate (pH 4) and acetonitrile and injected into HPLC. Curcumin was separated on a Waters C18column with gradient elution and was mom tion and AA release, as well as COX and LOX pathways of AA tored at a 380-nm wavelength in a Waters 990 photodiode array detector. The metabolism produced by exogenous agents, may alter tumorigenesis. results indicate that >96% of curcumin could be accounted for in feed samples It was, therefore, of interest to study the efficacy of a low dietary stored in a cold room for 14 days. level of pure curcumin as a chemopreventive agent in an established colon cancer model. In the present study, we report the chemopre Experimental Procedure ventive efficacy of dietary curcumin on AOM-induced colon tumor igenesis in male F344 rats. In addition, the effects of dietary curcumin The experiment was design to determine the efficacy of 2000 ppm curcumin on colonic mucosal and tumor PLA2, PLC'yl, COX, and LOX activ on AOM-induced colon carcinogenesis. Although curcumin administered in ities were analyzed to understand the possible modulating role of this the diet to rats at 100,000 ppm had no significant toxic effect (8), we have decided to use low dietary levels of curcumin, based on our previous study in agent in colon tumorigenesis. which 2000 ppm in the diet significantly inhibited colonic aberrant crypt foci development (20). As indicated in Fig. 2, beginning at 5 weeks of age, groups of animals were fed the control diet or the experimental diet containing 2000 MATERIALS AND METhODS ppm curcumin. At 7 weeks of age, groups of animals intended for carcinogen Materials treatment received AOM s.c., once weekly for 2 weeks at a dose rate of 15 mg/kg body weight. Animals intended for vehicle treatment were administered AOM (CAS:25843-45-2) was purchased from Ash Stevens (Detroit, Ml). an equal volume of normal saline. Animals were maintained on control or [â€˜4CJAA and PAPC were purchased from NEN-Dupont (Boston, MA). PIP2 experimental diets until the termination of the experiment. Body weights were and â€˜@I-PGE@RIAkit were obtained from Amersham (Arlington Heights, IL). recorded every 2 weeks for the first 10weeks and then every 4 weeks. Animals AA, 5(S)-, 8(S)-, 9(S)-, li(S)-, 12(S)-, and 15(S)-HETE as well as PGEI, were monitored daily for general health. The experiment was terminated 52 PGF@,, 6-Keto PGF1a, PGD2, and TxB2 were purchased from Cayman weeks after the second AOM treatment, at which time all animals were Chemical Company (Ann Arbor, MI); curcumin (>98% of diferuloylmethane) sacrificed by CO2 euthanasia. After laparotomy, the entire stomach, small was purchased from Janssen Chemicals (Beerse, Belgium). The normal phase intestine, and large intestine were resected and opened longitudinally, and the HPLC (4.6 x 250 mm) silica columns were obtained from Alltech Associates, contentswere flushed with normal saline. Using a dissectionmicroscope, @ Inc. (Deerfield, IL), and the reverse phase HPLC (3.9 X 300 mm) Bondpak colon and small intestinal tumors were noted grossly for their location, num C18 column was purchased from Waters Associates (Milford, MA). Precoated bar, and size. For each tumor, the length (L), width (W), and depth (D) were Silica G plastic TLC plates were purchased from Fisher Scientific Co. measured with calipers. Estimates of tumor volume (V) were made using the (Springfield, NJ). formula V = L x W x D x ir/6 (37). All other organs, including the kidney

Wk3 W@5 Wk7 Wk 8 - 52Weeks

Fig. 2. Experimental design for evaluation of chemopreventive efficacy by curcumin. __ Curcumin was fed 2 weeks prior to exposure to AOM, duringtreatment,anduntilthe termina .@ tit tion experiment. AOM was given to the sal Ousrantin. AOM AOM mals by s.c. at the beginning of 7 and 8 weeks Experimentaldiets of age, 15 mg/kg body weight. Sacrifice Histopathology Biochemical assays

CARCINOGEN: Azoxym.th.n. (AOM), s.c., 15 mgflig body weight, weekly for 2 weeks EXPERIMENTALDIETS: 0 or 2000 ppm curcumin diet 260

and liver, were also grossly examined under the dissection microscope for any PGE2 Production abnormalities. Colon tumors with a diameter of more than 0.4 cm were cut into two halves; one portion of the tumor was used for analyses of PtA2, PLC@y1, Colonic mucosa and tumors intended for PGE@analysiswere homogenized and COX and LOX metabolites, and the other one-half was used for his with a Polytron in 0.1 MTris-HCI buffer (pH 7.4) containing 20 mM EDTA. Er topathological examination of tumor types. Mucosa that was free of tumors in vivo production of PGE@was determined in colonic mucosal and tumor AOM-treated animals and from saline-treated animals was scraped from each homogenates (0.3 ml) by incubating them at 37Â°Cfor0 (basal level) and 15 colon for biochemical analysis according to our previously described method mm (ex vivo PGE@production). All the incubations were terminated by adding (37). Colonic mucosa and portions of tumors intended for biochemical deter 5.6 @LMindomethacin.Then 0.5 ml ice-cold methanol was added to each minations were quickly frozen in liquid nitrogen and stored at â€”80Â°C. incubationmixtureand mixedvigorously.Afteracidifyingthesamplesto pH For histopathologicalevaluation,tumorswere fixed in 10%bufferedfor 3.5with 1%formicacid,theaqueouslayerwasextractedwithanequalvolume maim, embedded in paraffin blocks, and processed by routine procedures with of chloroform. Following centrifugation at 2000 X g for 20 mm, the organic hcrnatoxylin and eosin staining. The stained sections were examined histolog phase was removed and evaporated to dryness under N2. The dried extract was ica.ilyfor tumor types according to the classification of Pozharisski (38) with resuspended in the assay buffer for RIA of PGE@. Extraction of samples minor modifications. Most of the colon tumors in this experiment were typically results in <100% recovery of [email protected], recovery esti adenocarcinornas, either invasive or noninvasive. The invasive adenocarcino mates were made by adding 3000 dpm of tritiated PGE@tothe sample prior to mas were mostly signet ring mucinous type, invading muscularis mucosa deep processing. Corrections for the proportion of analytically recovered PGE@was into the intestinal wall and beyond. The noninvasive adenocarcinomas were made by measuring the tracer in an aliquot after extraction. RIA was done those growing outward towards the intestinal lumen and not invading the under equilibrium conditions according to standard methodology (41). The muscularisrnucosa.Theywereusuallywell differentiatedadenocarcinomas. resultsare expressedas ng PGE@/mgprotein.

BiochemicalAna1@ LOX and COX Activities

Samples of colomc mucosa and tumors for PtA2 and PLC'yl assay were Colonic mucosa and tumors from individual animals were homogenized in homogenized in 1:3 (w/v) volumes of homogenizing buffer containing 30 m@s 1:3 (w/v) volumes of 100 mMTris-HCI buffer (jH 7.2) using a Polytron tissue me-Ha (pH 7.4), 140 mi@@NaCI,5 mt@iKCI, 20 @MEDTA, 10 g@g/ml homogenizer. The samples were then centrifuged at 9000 X g at 4Â°Cfor10 leupeptin, 50 p@g/mltrypsin inhibitor, and 1 m@iphenylmethylsulfonyl fluo min. The supernatant fraction was centrifuged at 100,000 X g for 1 h. The ride, and the homogenates were centrifuged at 100,000 X g at 4Â°Cfor1 h. The resulting supernatant was used for LOX activity. Microsomal pellets were resulting supernatant fraction was used for cytosolic PtA2 activity, and the resuspended in 50 mM potassium phosphate buffer (pH 7.4) for assay of COX pellet fraction was redissolved in 30 mM HEPES-NaOH buffer (pH 7.2) activity. containing 0.2% Triton X-100 and used for the analysis of membrane-bound Cyclooxygenase Activity. The COX activity of colonic mucosa and tu PLC'yl activity. mors was measured by previously published methods (42, 43). Briefly, 150 pJ @2Activity. Cytosolic PLA2 activity was measured by the method of reaction mixture containing 12 @M[â€˜4CIAA(420,000dpm), 1 mMepineph Leslie (39) with some modifications using [â€˜4CJPAPC(40-60mCi/mmol) as nine, 1 mMglutathione in 50 mMphosphate buffer, and 25â€”35@gofmucosal substrate. PLA2activity of cytosolic proteins was carried out in a total volume or tumor microsomal protein was incubated at 37Â°Cfor15 min. The reaction of a 100.j.d reaction mixture containing 50 m@ssodiumHEPES (pH 7.3), 0.8 was then terminated by the addition of 40 @tlof 0.2 M HC1. The COX mM Caa2, 0.02% Triton X-100, and 20â€”30g.@gof cytosolic protein. The metabolites of AA were extracted three times with 0.5 ml of ethyl acetate. The reaction was initiated by adding 40 @MofPAPC (10 g.@Ci/@.unol,adjustedwith combined extracts were evaporated to dryness under N2 and redissolved in coldsubstrate).Thereactionmixturewasincubatedat37Â°C a shakingwater chloroform and subjected to TLC using Silica 0. The TLC plates were bath for 30 mm. The reaction was terminated by the addition of 300 @d developed in a solvent system containing chloroform:methanol:acetic acid: chloroforrn:methanol(3:2, v/v). An additional 200 @.dchloroformwas added to water (100:15:1.25:1, v/v/v/v) and were exposed in an iodide chamber for 5 each sample and mixed thoroughly. The samples were then centrifuged, and mm for visualization of the standards. The metabolites of [14CIAAcorrespond the chloroformlayerwas separatedandevaporatedto drynessunderN2. Five ing to PGE@,PGF@,,PGD2, 6-keto PGF1@,andTxB2 were detected by their ,LgAA was added to dried extract and redissolved in chloroform. An aliquot comigration (Rfvaiues) with authentic standards. The area of each metabolite of chloroform extract was then subjected to TLC on precoated plastic TLC was determined with a Bioscan System 200 image-scanning counter equipped plates (Silica 0). The TLC plates were developed with a solvent system with a f3-detector. containing chloroform:methanol:acetic acid:water (90:12:2:1, v/v/v/v) and cx LOX Activity. Colonic mucosal and tumor LOX activity was determined posed in an iodide chamber for 5 min for visualization ofAA. The area of each by the modification method of Huang et a!. (16) and Rao et al. (43). In brief, [â€˜4C]AAmetabolitewas determined with a Bioscan system 200 image-scan this method involved HPLC measurement of â€˜4C-labeled5(S)-, 8(S)-, 9(S)-, ning counter (Bioscan Inc., Washington, DC) equipped with a a-detector. 11(S)-, 12(5)-, and 15(S)-HETEs that were formed from the [14CJAA.The Protein content was determined by the Bio-Rad method. Results are expressed reaction mixture (200 gil) containing 100 mM Tris-HC1 (pH 7.2) and 2 mM as prnol [14CJAAreleased/mg protein/min. CaCl2 [â€˜4C]AA(6nmol, 480,000 dpm) and cytosol fraction (300â€”500@tg PLCy1 Activity. Membrane bound PLCy1 activity was measured by the protein) was incubated for 15 min at 37Â°C.Thereaction was terminated by the method of Bleasdale et a!. (40) with some modifications using [3H}PIP2(1â€”5 addition of 12 p.1 of 0.2 M H@, and the metabolites of [â€˜4C]AAwere extracted Ci/mmol) as a substrate. PLCyl activity of membrane proteins (100â€”200 @g) with 0.6 ml of ethyl acetate three times. The HETES were analyzed by normal phase HPLC as described previously (20, 28). was carried out in a total volume of 250 @&lreactionmixture containing 30 mM HEPES-NaOH buffer (pH 7.2), 5 mMDDT, 4 nmiCaCl2,2 nmsEGTA, 0.9 m@t MgSO, and 50 @M[3H]PIP2(50 @CWmmol).Thereactionwas initiatedby Statistical Analysis addingsubstratetothemixtureandincubatingat37Â°Cfor20 minin a shaking Body weights, tumor incidence, tumor multiplicity, tumor volume and water bath. The reaction was terminated by the addition of 0.2 ml of chloro biochemical parameters were compared between the animals fed the control form:rnethanol (1:2, v/v), followed by 0.3 ml of 1 M HG. The incubation and curcumin diets. Tumor incidence, which is expressed as the percentage of mixture was mixed vigorously and then centrifuged to yield two phases. An animal with tumors, was analyzed statistically by X2test. Tumor multiplicity, aliquot of 0.3 ml of aqueous layer containing [3H]inositol 1,4,5-triphosphate expressed as mean number of tumors/animal, was analyzed by the unpaired was transferred to a scintillation vial containing 10 ml of scintillation cocktail, test accounting for unequal variance. Differences in body weights, tumor and radioactivity was counted in a Beckman model LD6800 scintillation volume, and biochemical parameters between the groups were analyzed sta counter. The activity is expressed as pmol of [3H)inositol 1,4,5-triphosphate tistically by the Student t test and analysis of variance. Differences were formed from [3HJP1P1/mgprotein/iS min. considered statistically significant at P < 0.05. 261

ratsExperimental Table 1 Effectofdietary curcwninon body weightgain in male F344 weekâ€•049 weights (g) of animals on experimentaldiet at 22324252AOM-treatedgroupNo. of animalsBody 14

Controldiet 317Â±22 369Â±22 2000 ppm curcumin diet36 3073@5b 73 Â±4190Â±12194 Â±12260Â±16265 Â±15 322 Â±21 376 Â±20418Â±27426 Â±24437Â±27444 Â±26448Â±32456Â±27 Saline-treated Controldiet 12 73Â±5 200Â±9 268Â±12 321Â±15 378Â±19434Â±24457Â±27469Â±26380Â±17435Â±22460Â±22472Â±25 2000ppmcurcumindiet 12 ______73Â±5 198Â±8 269Â±10 324Â±13

a At s weeks of age, groups of animals were fed control or 2000 ppm curcumin diet. This period is denoted as 0 weeks. bMeanÂ±SD.

RESULTS of PGE@ in the colonic mucosa and tumors of animals treated with AOM or vehicle. General Observations. The body weights of animals treated with As summarized in Table 5, the results of COX metabolites in vehicle or AOM and fed the control and curcumin diets were corn colonic mucosa demonstrate that AOM treatment had minimal parable throughout the study (Table 1). In vehicle-treated animals, the effect on the production of PGs and TxB2. Markedly increased chronic feeding of curcumin did not produce any gross changes in the levels (3â€”5-fold) of PGs and TxB2 were observed in the colonic liver, kidney, stomach, intestine, or lungs or any kind of histopatho tumors of animals fed the control diet when compared to colonic logical changes in the liver or intestine attributable to toxicity. mucosa of animals fed control diet. Animals fed the curcumin diet Tumor Incidence. Table 2 summarizes the AOM-induced colon showed significantly lower levels of PGs (25â€”50%)in the colonic tumor incidence (jercentage of animals with tumors) and multiplicity mucosa and tumors compared to those fed the control diet In (number of tumors/animal). There was no evidence of tumors in contrast, administration of curcumin had no measurable effect on vehicle-treated animals fed the control or curcumin diet. The results colonic mucosal and tumor TxB2. indicate that administration of curcumin significantly inhibited the The effect of dietary curcumin on colonic mucosal and tumor LOX incidences of noninvasive (P < 0.015) and total (invasive plus non metabolites is shown in Table 6. AOM administration had no signif invasive) adenocarcinomas (P < 0.004). Although dietary curcumin icant effect on the production of HETEs in the colonic mucosa inhibited invasive adenocarcinoma incidence to 47%, the differences compared to those treated with vehicle and fed similar diets. The did not reach a statistical significance (P = 0.054). With regard to levels of HETEs were significantly higher in colonic tumors corn tumor multiplicity, dietary curcumin significantly inhibited invasive pared to colonic mucosa. Feeding of curcurnin diet significantly (P <0.015)andnoninvasive(P<0.01)adenocarcinomasofthecolon. suppressed the colonic mucosal and tumor 5(5)-, 8(S)-, 12(5)-, and In addition, AOM-induced colon tumor volume was reduced to 57% 15(S)-HETEs formation to more than 49, 44, 47, and 27%, in animals fed curcumin as compared to those fed the control diet respectively. (Table 3). Biochemical Studies. The activities of PLA2 and PLOy! analyzed in colonic mucosa and tumors are summarized in Figs. 3 and 4. AOM DISCUSSION administration elevated the activities of colonic mucosal PLA2 and PLCyl, irrespective of dietary regimen. Interestingly, there was a The major aim of this investigation, which is a part of a large-scale 3â€”4-fold increase in the activities of PLA2 and PLCy1 in colon investigation to identify the compounds present in fruits and vegeta tumors when compared to surrounding colonic mucosa. Long-term bles for their potential chemopreventive properties, was to elucidate feeding of curcumin resulted in a significant suppression PLA2 and the colon tumor-inhibitory role of curcumin, a naturally occurring PLC'yl activities in colonic mucosa and in tumors. antiinflamrnatory agent. Previous studies have demonstrated that top Table 4 summarizes the effect of dietary curcumin on basal levels ical application and dietary administration of curcumin inhibited and ex vivo production of PGE@in the colonic mucosa and tumors. As DMBA-induced skin and B(a)P-induced forestomach tumors in mice, expected, ex vivo production of PGE@was higher than their respective respectively (17). A recent study in mice which showed that dietary basal levels. Also, AOM treatment significantly increased the basal administration of 5,000â€”20,000 ppm curcumin reduced the incidence and ex vivo production of PGE@in the mucosa of animals as compared of intestinal tumors (19), as well as another study from our laboratory to their vehicle-treated counterparts. PGE@ levels were markedly that demonstrated an inhibitory effect of dietary curcurnin on colomc higher in colon tumors than in mucosa. Administration of curcumin aberrant crypt foci (20), provided an impetus to investigate the effect significantly inhibited both basal levels as well as ex vivo production of this agent in a well-established colon cancer model. To our

Table 2ratsTumor Effect of dietary curcwnin on AOM-induced colon adenocarcinomaincidence in male F344 incidencea (% animals with adenocarcinoma) (Adenocarcinomas/animal)invasivemultiplicity

Experimental diets Invasive Noninvasive TOta1bTumor NoninvasiveTotal AOM-treated Control diet 3867810.531.12037C.I47C.2oio Â±0.70.97 Â±0.91.50 Â± 2000 ppm Curcumin o.@'â€•000000 Â±0.4'@0.46 Â±06d.2o.o@ Â± Saline-treated 2000 ppm Curcumin

a Percentage of animals with invasive and noninvasive adenocarcinomas. bTotaltumorsrepresentinvasiveandnoninvasiveadenocarcinomas. CSignificantlydifferent from controldiet groupby [chil2 test,â€˜P< 0.015;2p < O.004. @ dSignificantlydifferentfromcontroldietgroupbytheStudentttest,â€˜P< 0.015;2p 0.01; P < 0.001. 262

Table 3 Effect ofdietary curcumin on AOM-induced colon tumor size and volume in duced no gross changes in the liver, kidney, stomach, intestine, and male F344 rats lungs. It is also noteworthy that, when compared to other naturally dietSize0â€”0.5TumorsizeandvolumeControl diet2000 ppm curcumin occurring colon cancer chemopreventive agents, such as dithiole thiones and diallyl disulfide, to cite a few, curcumin produced a better (70)0.5â€”1.0cm26â€• (488)b14 (33.3)6(30)>1.0cm18 or equally potent colon tumor-inhibitory action (44, 45). Interestingly, cm10 (18.5)0(0) curcumin fed even at 5â€”10%in the diet had no measurable toxic Volume effects in the animals (46) as compared to substituted dithiole thiones, Tumor volume (mm3) 133 Â±24Oc 56 Â±68(58)d such as oltipraz, anethole trithione, and diallyl disulfide, which pro a Number of tumors having particular size. bPercentagenumberoftumorshavingparticularsize. duced significant toxicity even at 0.05% in the diet (44, 45). CMean Â±SD. Although the precise mechanism by which curcumin inhibits the dPercentagetumorsuppression. AOM-induced colon tumorigenesis has not been established, it would appear that one possible action involves antiinflammatory activity by knowledge, this is the first report to provide the evidence that low curcumin. Previously, Srimal and Dhawan (1 1) showed that either levels (2000 ppm in the diet) of curcumin significantly inhibit the oral or i.p. administration of curcumin effectively inhibited carrag incidence, multiplicity, and size of adenocarcinomas of the colon in eenin-induced acute inflammation in mice and rats. In addition, 5ev this established animal model. The results of the present study are of eral studies have also demonstrated the antiinflammatory action of great interest because long-term feeding of curcumin not only signif curcumin on laboratory rodents by inducing the inflammation with icantly inhibited AOM-induced colon tumorigenesis but also pro carrageenin and kaolin (reviewed in Ref. 8). Several previous studies

I00

I 75

Fig.3. Effectof dietarycurcuminon colonic mucosal and tumor cytosolic PtA2 activity in male 50 F344rats.Valuesare mean(bars, SD;n = 6); P ii values are significantly different from their saline/ AOM-treatcd controls by analysis of variance.

25 I

0 Colonic Mucosa Colonic Tumors

150

.@ E

I 00

Fig. 4. Effect of dietary curcuminon co lonic mucosal and tumor PLC'yl activity in male F344 rats. Values are mean (bars, SD; I n 6). P values are significantly different from their saline/AOM-treated controls by I analysis of variance. IP@.,inositol 1,4,5-triphos @ 50 phate. I 0 Colonic Mucosa Colonic Tumors 263

Table 4 Effect of dietary curcumin onratsSaline-treated AOM-induced colonic mucosai and tumor PGE2 levels in male F344 AOM-treatedExperimental

@ vivoMucosaControlgroups Basal level Er Basal level Er

0.92000diet 0.24Â±[email protected] 0.93Â±0.31 0.63Â±0.2 2.11Â± 026dTumorsControlppm Curcumin 0.13 Â±0@d 0.44 Â±0.2'@ 0.40 Â±0.1 0.90 Â±

2.62000diet 4.74 Â±1.2 11.7 Â± 1.4â€•a ppm Curcumin 2.93 Â±01d 7.2 Â±

Samples were incubated at 37Â°C for 15 mm for PGE@ synthetic activity. protein.Cb ng of PGE@/mg Mean Â±SD (n = 6). 0.05.haved Significantly different from control diet fed groups by the Student t test, P <

byseveralestablished that AA metabolites may play a modulatory role in promotion (42, 48). Thus, the inhibition of colon adenocarcinomas immunological and inflammatory diseases (22). The results of curcumin was consistent with the reduction in COX and LOX metab our present study demonstrated that the levels and production of POs olites in the colonic mucosa and tumors, suggesting that the chemo in colon tumors were higher than in colonic mucosa, suggesting an preventive action of curcumin might be mediated through the inhibi metabolites.roleincreased synthesis of COX metabolites in tumors. In addition, the tion of production of COX and LOX andtionof COX metabolites, particularly PGE2, in colon tumor promo- In the present experiment, we studied the colonic mucosal forlaboratoryhas been established (21, 34, 35). Earlier studies from our tumor levels of PLA2 and PLCy1, which are dominant pathways diacylglycerolcam,and others have shown that PG inhibitors, such as piroxi- the AA release (Fig. 5). Also, PLC'yl is responsible for cellin indomethacin, sulindac, and aspirin, inhibit colon tumorigenesis formation and protein kinase C-dependent signal transduction and AAtumorrodents (21, 32). LOX metabolites such as 12(S)-HETh promote proliferation (49). One of the pathways leading to generation of includetumorcell adhesion, stimulate tumor cell spreading, and augment the involves a direct action of PLA2 on a phospholipid that could cell metastatic potential (23â€”25).Also, a positive correlation 1,2-diacyl- or 1-O-alkyl-2-acyl-phosphatidylinositol, phosphatidyl wasbymation, observed between the levels of 8(S)-HETh and degree of inflam- ethylamine, or phosphatidylcholine. The second pathway mediated hyperproliferation, clastogenicity, and tumor development PLC'yl involves the degradation of phosphatidylinositol 4,5-biphos inducedbyHETEs, by TPA (47). In addition, the activities of 5(S)- and 15(S)- phate via a sequence of reactions beginning with PLC'yl, followed which are potent modulators of inflammation suppressed by diglyceride lipase and monoglyceride lipase (27). Our results demon lipoxygenase inhibitors, indicateandTable a mediating role of HETEs in tumor strated that dietary curcumin significantly inhibited the PLA2

5 Effect ofdietary curcuminratspmoles on colonic mucosal and tumor COX activity in male F344 minExperimental of PGs and TxB@formed from [â€˜4CJAA/mgprotein/15

TxB2MucosaSaline-treatedControldietgroup PGE@ PGF2@ POD2 6-keto PGF1@

278Â±402000 245Â±32â€• 280Â±28 156Â±31 325Â±34 38(5)AOM-treatedControlppm curcumin 148 Â±21@(39)c 211 Â±27â€•(25) 114 Â±24â€•(27) 212 Â±31â€•(35) @5Â±

322000 diet 328 Â±34 355 Â±43 242 Â±33 378 Â±41 258 Â± @ 264Â±36TumorsControlppm curcumin 184 Â±23â€• 236 Â±41â€• 156 Â±17â€•(30) 284 Â±35(25)

@ Â±2000 diet 1578Â±116d Â±108â€• 549 Â±77â€• 1193Â±157â€• 972 (19)a ppm curcumin 789 Â±88â€•(50) 543 Â± @b(42) 375 Â±59(32) 820 Â±73(31) 788 Â±93

Mean Â± SD (n = 6â€”8). b0.05.C Significantly different from the respective control groups by the Student t test, P < Values in the parentheses are the percentage of inhibition from their respective control groups. d Significantly different from AOM-treated0.0001.Table control group mucosal values by the Student t test, P <

6 Effect of dietary curcumin on colonicratspmol mucosal and tumor WX activity in male F344 mmExperimental of HETEas producedfrom [14CJAA/mgprotein/iS 15(S)-HETEMucosaSaline-treatedControlgroup 5(S)-HETh 8(S)-HETE 12(S)-HETE

237Â±392000diet 178 Â±29â€• 272 Â±36 242 Â±39 ppm curcumin 84 Â±l3c(53)@@ 144 Â± @C(47) 123 Â±14c(49) 173 Â±31(27) AOM-treated Control diet 211Â±33312Â±42266Â±37308Â±5293 2000 ppm curcumin (38)312Â±30â€•348Â±44585@83d428Â±69â€•158Â±17'@(56)176 Â±31c(44)140 Â±18'@(47)189 Â±43C Tumors Control diet 2000 ppm curcumin Â±â€”27'@(49)224 Â±35C(36)253 Â±56c(57)212 Â±48' (50)

a Mean Â± SD (n = 6). b Values in the parentheses are the percentage of inhibition from their respective control groups. C Significantly different from their respective controls by the Student t test, P < 0.01. d Significantly different from colonic mucosal values by the Student t test, P < 0.0001. 264

In conclusion, the present study demonstrates that dietary curcumin significantly inhibited AOM-induced colon tumorigenesis in male F344 rats. In addition, curcumin significantly suppressed the colonic mucosal and tumor PLA2, PLCyl, and COX and LOX activities, PC PIP2 which are relevant to colon carcinogenesis. Although the exact mech anisms of chemopreventive action of curcumin remain to be eluci dated, it would appear that modulation of AA metabolism by curcu I @@PLCy1min may play a role in its inhibitory action. Based on our current PLA2 efficacy study, the lack of toxicity and side effects, as well as its 1p3+ DAGâ€” availability in large quantities as natural products that has been used in population groups for several centuries, further studies are war ranted to test the colon cancer chemopreventive action of curcumin in i,@â€”DAGhuman clinical trials. It is reasonable to state that we believe curcumin possesses several advantages over other synthetic nonsteroidal anti AMG inflammatory drugs such as sulindac, piroxicam, and aspirin that are already in human clinical trials. ) AAâ€•@'@ lipase Acyl PC ACKNOWLEDGMENTS

We thankLauraDiScioriofor preparationofthe manuscriptandthe staffof the Research Animal Facility and Histopathology Facility for expert technical /\ assistance. REFERENCES 1. Boring, C. C., Squires, T. S., Tong, T., and Montgomery, S. Cancer Stal, 44: 7-26, 1994. /\ 2. National Research Council. Inhibitors of carcinogenesis. In: Diet, Nutrition and PGs TXs HETEs ITs LXs Cancer, pp. 358â€”370.Washington,DC: National Academy Press, 1982. 3. Wynder, E. L, Kajitani, T., Ishidawa, S ., Dada, H., and Takano, A. Environmental factors in cancer of colon and rectum. Cancer (Phila.), 23: 1210â€”1220,1969. Fig. 5. PLA2 and PLCyl pathways that may be involved in the release of AA from 4. Reddy, B. S. Diet and colon cancer@evidence from human and animal model studies. cellular phospholipids for the biosynthesis of COX and LOX metabolites. PC, phosphati in: B. S. Reddy and L A. Cohen (eds.), Diet, Nutrition and Cancer: A CritiCal dylcholine; Acyl PC, 1-acylphosphatidylcholine; PIP2, phosphatidylinositol 4,5-biphos phate;1P@,.inositol1,4,5-triphosphate;AMG.2-arachidonyl-monoglyceride;LTs.leukot Evaluation, pp. 47-65. Boca Raton, FL: CRC Press, 1986. 5. Wattenberg, L. W. Chemoprevention of cancer by naturally occurring and synthetic riencs, LXs, lipoxins. compounds. In: M. Wattenberg, C. W. Lipkin, C. W. Boone, and 0. J. Kdlloff(eds.), Cancer Chemoprevention, pp. 19-39. Boca Raton, FL: CRC Press, 1992. PLC'yl activities in the colonic mucosa and tumors. The exact mech 6. Boone, C. W., Kelloff, 0. J., and Malane, W. F. Identification of candidate cancer anism by which curcumin inhibits these enzyme activities are not chemopreventive agents and their evaluation in animal models and human clinical trials: a review. Cancer Res., 50: 2-9, 1990. clear. It may be possible that curcumin may exert inhibitory activity 7. Keiloff, 0. 1., Boone, C. W., Malone, W. E., and Steele, V. E. Recent results in by directly acting on PLA2 or PLC'yl, or alternatively, by acting on preclinical and clinical drug development of chemopreventive agents at the National Cancer Institute. In: L W. Wattenberg, M. Lipkin, C. W. Boone, and 0. J. Kelloff the regulators of PLA2 or PLCy1, resulting in decreased levels of AA (eds.), Cancer Chemoprevention, pp. 41â€”56.BocaRaton, FL: CRC Press, 1992. and its metabolite formation. We are not aware of any previous studies 8. Ammon, H. P. T., and WahI, M. A. Pharmacology of Curcuma longa. Plants Med., in which curcumin was tested on these enzyme activities. Based on 57: 1â€”7,1991. 9. Nadkarani, K. M. Curcwna longa@in: K. M. Nadkarani (ed), India Materia Medics, these findings, it is reasonable to state that curcumin may modulate pp. 414â€”416.Bombay:Popular Prakashan Publishing Co., 1976. not only PLA2 and PLC'yl to alter endogenous AA available as a 10. Tonnescn, H. H. Chemistry of curcumin and curcuminoids. in: C-T. Ho, C. Y. Lee, substrate for production of COX and LOX metabolites but also COX andM-T.Huang(eds.),PhenolicCompoundsinFoodandtheirEffectofHealth,Vol. 1: Analysis, Occurrence and Chemistry. Vol. 1. ACS Symposium Series No. 506, pp. and LOX pathways. Thus, the results from this study further support 143-153. Washington, DC: American Chemical Society, 1992. the modulatory role of curcumin as a dual inhibitor of AA 11. Srimal, R. C., Dhawan, B. N. Pharmacology of diferuloylmethane (curcumin), a non-steroidal antiinflammatory agent. 3. Pharm. Pharmacol., 25: 447â€”452,1973. metabolism. 12. Satoskar, R. R., Shah, S. J., and Shenoy, S. G. Evaluation of antiinflammatory In addition, it is also possible that inhibition ofAOM-induced colon property of curcumin (diferuloyl methane) in patients with postoperative inflamma carcinogenesis by curcumin administered during the initiation phase tion. Int. J. Chin.Pharmacol. Ther. Toxicol., 24: 651â€”654,1986. 13. Sharma, 0. P. Antioxidant activity of curcumin and related compounds. Biochem. may be mediated through the modulation of AOM metabolism, which Pharmacol., 25: 1811â€”1812,1976. is mediated through the cytochrome P450 2E1 system. The metabolic 14. Teds, S., Miyssc, T., Arichi, H., Tanizawa, H., and Takino, Y. Natural antioxidant Ill. activation of AOM takes place in two steps, i.e., the hydroxylation of Antioxidative components isolated from rhizome of Curcuma longa L Chem. Pharm. Bull. (Tokyo), 33: 1725â€”17281985. AOM to methylazoxymethanol in the liver and the oxidation of 15. Huang, M-T., Smart, R. C., Wong, 0-0., and Conney, A. H. Inhibitory effect of methylazoxymethanol to methylazoxyformamide in the liver and co curcumin, chlorogenic acid, caffeic acid, and ferulic acid on tumor promotion in mouse skin by 12-O-tetradecanoylphorbol-13-acetate. Cancer Res., 48: 5941â€”5946, lon (50). Although there is no direct evidence that curcumin modu 1988. lates the metabolism ofAOM, another antiinflammatory drug, aspirin, 16. Huang,M-T.,Lysz,T., Ferraro,T.,Abidi,1. F., Laskin,J. D., andConney,A. H. has been shown to suppress AA-induced decomposition of methyla Inhibitory effects of curcumin on in vitro lipoxygenase and cyclooxygenase activities in mouseepidermis.CancerRca.,51: 813â€”819,1991. zoxymethanol, a metabolite of AOM, to formaldehyde in colonic 17. Huang, M-T., Wang, Z. Y., Georgiadis, C. A., Laskin, J. D., and Conney, A. H. mucosal homogenate. In this connection, Huang et a!. (51) showed Inhibitory effect of curcumin on tumor initiation by benzo[a@pyrene and that TPA-induced c-jun/AP-1, an early gene, activation was signifi 7,12-dimethylbenz[ajanthracene. Carcinogenesis (L.ond.),13: 2183â€”2186,1992. 18. Azuine, M. A., and Bhide, S. V. Chemopreventive effect of tumeric against stomach cantly suppressed by curcumin in fibroblast cells. Further studies on and skin tumors induced by chemical carcinogens in Swiss mice. Nutr. Cancer, 17: the effect of curcumin on AOM metabolism, arachidonic acid metab 77â€”83,1992. olite formation, and early gene activation could clearly provide the 19. Huang, M. T., Ma, W., Lou, Y-R., Ferraro, 1., Reuhl, K., Newmark, H., and Conney, A. H. Inhibitory effect of dietary curcumin on gastrointestinal tumorigenesis in mice. possible mode of action of curcumin in colon carcinogenesis. Proc. Am. Macc. Cancer Rca., 34: 555, 1993. 265

20. Rao, C. V., Simi, B., and Reddy, B. S. Inhibition by dietary curcumin of azoxymeth 36. Reddy, B. S., and Sugie, S. Effect ofdifferent levelsof x-3 fatty acids on azoxymeth ane-induced ornithine decarboxylase, tyrosine protein kinsse, arachidonic acid me ane-induced colon carcinogenesis in F344 rats. Carner Rca., 48: 6642-6647, 1988. tabolism and aberrant crypt foci formation in the rat colon. Carcinogenesis (Land.), 37. Ran, C. V., Rivenson, A., Katiwalls, M., Kelloff, 0. J., and Reddy, B. S. Oicmo 14:2219â€”2225,1993. preventive effect of oltipraz during different stages of experimental colon carcino 21. Marnett, L. J. Aspirin and potential role of prostaglandins in colon cancer. Cancer genesis induced by azoxymethane in male F344 r*s. Cancer Res., 53: 2502â€”2506, Res., 52: 5575â€”5589,1992. 1993. 22. Smith, W. L Prostanoid biosynthesis and mechanisms of action. Am. J. Physiol., 263: 38. Pozharisski, K. M. Tumors of the intestines. in: V. Turcusov and V. Mohr (eds.), F181â€”F191,1992. Pathology ofTumors in Laboratory Animals, Vol. 1,Tumors ofthe Rat, pp.159-198. 23. Hom@,I( V., Gropssi, I. M., Steinert, B. W., Chopra, H., Onoda, J., Nelson, K. K., and Lyon: IARC Publications, 1990. Taylor, J. D. Lipoxygenase regulation of membrane expression of tumor cell glyco 39. Leslie, C. C. Mscrophage phospholipase A2specific for sn-2-arschidonic acid., in: R. proteins and subsequent metastasis. Adv. Prostaglandin Thromboxane Leukotriene C. Murphy and F. A. Fitzpatrick (eds.), Methods in Enzmology, Vol. 187, Arachi Res., 19: 439â€”443, 1989. donate Related Lipid Mediators, pp. 216â€”225.NewYork: Academic Press, 1990. 24. Timer, J., Chen, Y. Q., Liu, B., Bazar, R., Taylor, J. D., and Honn, K. V. The 40. Bleasdale, J. E., McOuire, J. C., and Bals, 0. A. Measurement of phosphoinositide lipoxygenase metabolite 12(S)-HErE promotes allb @3integrin-mediatedtumor-cell specific phospholipase C activity. Methods Enzymol., 187: 226â€”237,1990. spreading on fIbronectin. lnt. J. Cancer, 52: 594â€”603,1992. 41. Rao, C. V., and Reddy, B. S. Modulating effect of amount and types of dietary fat on 25. Honn, K. V., and Tang, D. 0. Adhesion molecules and cancer cell interaction with omithine decarboxylase, tyrosine protein kinase and prostaglandins production during endothelium and subendothelial matrix. Cancer Metastasis Rev., ii: 353â€”375,1992. colon carcinogenesis in male F344 rats. Carcinogenesis (Land.), 14: 1327â€”1333, 26. Neufeld, E. J., and Majerus, P. W. Arachidonste release and phosphatidic acid 1993. turnover in stimulated human platelets. J. Biol. Chem., 258: 2461â€”2467,1983. 42. Fischer, S. M., Baldwin, J. K., Jasheway, R. W., Patrick, K. E., and Cameron, (3. S. 27. Dennis, E. A., Rhee, S. G., Billab, M. M., and Hannun, Y. A. Role of phospholipases Phorbol ester induction of 8-lipoxygenase in inbred SENCAR (SSIN) but not in generating lipid second messengers in signal transduction. FASEB J., 5: C57BLI6J mice correlated with hyperplasia, edema, and oxidant generation by not 2068â€”2077,1991. ornithine decarboxylase induction. Cancer Rca., 48: 658â€”664,1988. 28. Cantley, L C., Auges, K. R., Carpenter, C., Duckworth, B., Graziani, A., Kapeller, R., 43. Rao, C. V., Desai, D., Simi, B., Kulksrni, N., Amin, S., and Reddy, B. S. Inhibitory and Soltoff, S. Oncogenes and signal transduction. Cell, 64: 281â€”302,1991. effect of caffeic acid esters on azoxymethane-induced biochemical changes and 29. Perrella, F. W., Jankewies, R., and Dandrow, E. A. Phospholipase C from human aberrant crypt foci formation in rat colon. Cancer Res., 53: 4182â€”4188,1993. melanoma: purification and characterization of a phosphatidylinositol-selective en 44. Rao, C. V., Tokumo, K., Kelloff, 0., and Reddy, B. S. Inhibition by dietary oltipraz zyme. Biochim. Biophys. Acta., 1076: 209â€”214,1991. of experimental intestinalcarcinogenesis induced by azoxymethane in male F344 rats. 30. Arteaga, C. L., Johnson, M. D., Todderud, G., Cofey, R. J., Carpenter, G., and Page, Carcinogenesis (Land.), 12: 1051â€”1056,1991. D. L Elevated content of the tyrosine kinase substrate phospholipase CYI in primary 45. Reddy, B. S., Rao, C. V., Rivenson, A., and Kelloff, 0. J. Chemoprevention of colon human breast carcinomas. Proc. NatI. Acad. Sci. USA, 88: 10435â€”10439,1991. carcinogenesis by organosulfur compounds. Cancer Res., 53: 3493-3498, 1993. 31. Soydan, A. S., Tavares, I. A., Weech, P. IC, and Bennett, A. High molecular weight 46. Ssmbaiah, K., Ratnakumsr, S., Kamanna, V. S., Satyanarayans, M. N., and Rso, phospholipase A2: its occurrence and quantification in human gut cancer and normal M. V. L Influenceof turmeric and curcumin on growth, blood constituents and serum mucosa. Eicosanoids and other Biosctive Lipids in Cancer, Inflammation Radiat. enzymes in rats. J. Food Sd. Technol., 19: 187â€”190,1982. Injury, 3: 66, 1993. 47. FstenbUeger, 0., Schurich, B., Kaina, B., Petrusevska, R. T., Fuesning, N. E., and 32. Reddy, B. S., Rao, C. V., Rivenson, A., and Kelloff, G. J. Inhibitory effect of aspirin Marks, F. Tumor induction in initiated mouse skin by phorbol esters and methyl on azoxymethane-induced colon carcinogenesis in F344 rats. Carcinogenesis (Land.), methanesulfonate: correlation between chromosomal damage and conversion (â€œstage 14: 1493â€”1497,1993. I of tumor promotionâ€•)invivo. Carcinogenesis (Land.), 10: 749â€”752,1989. 33. Narisawa, T., Kusaka, H., Yamazaki, Y., Takahashin, M., Koysma, H., Koyains, K., 48. Bond, L., Hagege, J., Sraer, J., Rondeau, E., Perez, J., and Ardaillau, R. Reactive Fukaum, Y., and Wakizaka, A. Relationship between blood plasma prostaglandin E@ oxygen production by cultured rat glomerular mesanglal cells during phagocytosis is and liver and lung metastases in colorectal cancer. Dis. Colon Rectum, 33: 840â€”845, associated with stimulation of lipoxygensse activity. 3. Exp. Med., 158: 1836â€”1852, 1990. 1993. 34. Verma, A. K., Ashendel, C. L., and Boutwell, R. K. Inhibition by prostaglandmn 49. Nishzuka, Y. The role of protein kinase C in cell surface signal transduction and synthesis inhibitors of the induction of epidermal ornithine decarboxylase activity, the tumor promotion. Nature (Land.), 308: 639â€”698,1984 accumulation of prostaglandins, and tumor promotion caused by 12-O-tetradecanoyl 50. Fiala, E. S. Investigations into the metabolism and mode of colon carcinogens, phorbol-13-acetate. Cancer Res., 40: 308â€”315,1980. 1,2-dimethylhydrazineand szoxymethsne. Cancer (Phila.), 40: 2436â€”2445,1977. 35. Metzger, U., Meier, J., Uhlschmid, 0., and Weihe, H. Influence of various prostag 51. Huang, T-S., Lee, S-C., and tin, J-K. Suppression of c-Jwz/AP-1 activation by an landin synthesis inhibitors on DMH-induced ratcolon cancer. Dis. Colon Rectum, 27: inhibitor of tumor promotion in mouse fibroblast cells. Proc. Natl. Acad. Sd. USA, 366â€”369,1984. 88: 5292â€”5296,1991.

266

Downloaded from cancerres.aacrjournals.org on September 23, 2021. © 1995 American Association for Cancer Research. Chemoprevention of Colon Carcinogenesis by Dietary Curcumin, a Naturally Occurring Plant Phenolic Compound

Chinthalapally V. Rao, Abraham Rivenson, Barbara Simi, et al.

Cancer Res 1995;55:259-266.

Updated version Access the most recent version of this article at: http://cancerres.aacrjournals.org/content/55/2/259

E-mail alerts Sign up to receive free email-alerts related to this article or journal.

Reprints and To order reprints of this article or to subscribe to the journal, contact the AACR Publications Subscriptions Department at [email protected].

Permissions To request permission to re-use all or part of this article, use this link http://cancerres.aacrjournals.org/content/55/2/259. Click on "Request Permissions" which will take you to the Copyright Clearance Center's (CCC) Rightslink site.