Structure-Activity Relationships of Retinoids in Hamster Trachea! Organ Culture

[CANCER RESEARCH 40, 3413-3425, October 1980]

Dianne L. Newton, William R. Henderson, and Michael B. Sporn1

Laboratory of Chemoprevention, National Cancer Institute. Bethesda, Maryland 20205

ABSTRACT activity of new retinoids, the concentration of which may be as low as 10~'Â°to 10~" M during the assay procedure. Thus, it Structure-activity relationships are summarized for 87 reti- is possible to measure biological activity with less than 1 mg of noids, using reversal of keratinization in the hamster trachÃ©al a new retinoid; with radioactively labeled retinoid metabolites, organ culture system to measure biological activity. Classes of assays have been performed with only a few jug of material. compounds evaluated include all-frans-retinoic acid and its The length of assay is relatively brief, and test results may be esters, ring-modified analogs of all-frans-retinoic acid and its evaluated within 1 month after beginning the assay. esters, side-chain-modified analogs of all-frans-retinoic acid This article provides data on 87 retinoids, from a total set of and its esters, analogs in which both ring and side chain have over 30,000 hamster tracheas which have been used for as been modified, all-frar/s-retinol and derivatives, all-frans-retinyl says at the National Cancer Institute. Each trachea has come amine derivatives, all-frar/s-retinal derivatives, all-frans-retinoic from a separate animal which had been raised on a vitamin A- acid amides, 13-c/s-retinoic acid and derivatives, and 5,6- deficient diet. From each hamster, the trachea was removed epoxyretinoids. The activity of many synthetic amide deriva under sterile conditions and maintained in organ culture in vitro tives of all-frar/s- or 13-c/s-retinoic acid approaches that of the for 3 to 10 days, as described below. Data are shown for parent compounds. No metabolite of all-frans- or 13-c/s-reti retinoids in which the ring, side-chain, and polar terminal group noic acid has yet been identified which has greater activity of the basic molecule have been modified. than the parent compounds in this assay. New synthetic deriv atives with a gem-dimethyl group at position 4 in the cyclo- MATERIALS AND METHODS hexenyl ring and two aromatic rings in the side chain have activity equal to or greater than that of all-frar/s- or 13-c/s- Standard Assay Procedure. The standard assay procedure retinoic acid, with some activity detectable in the 1CT11 M measures the ability of retinoids to reverse keratinization in a range. defined in vitro system (6, 19). Tracheas from hamsters that were in very early stages of vitamin A deficiency (5) were placed in organ culture. At the time of culture, the animals were INTRODUCTION 29 to 31 days old (they had been weaned at 21 days) and were This article summarizes data obtained during the past 7 still gaining some weight, with an average weight of 47 to 52 g. Their trachÃ©alepithelium was generally low columnar or cu- years in a collaborative testing program which has evaluated the biological activity of new synthetic retinoids, using the boidal, with only occasional patches of squamous metaplasia. hamster trachÃ©alorgan culture assay developed in the labo Each trachea was opened from the larynx to the carina along the membranous dorsal wall and cultured in a serum-free ratories of the Lung Cancer Branch and Laboratory of Chem medium (CMRL-1066 supplemented with crystalline bovine oprevention of the National Cancer Institute. This testing has involved a collaborative effort on the part of the United States insulin, 1.0/ig/ml; hydrocortisone hemisuccinate, 0.1 ftg/ml; government; the pharmaceutical industry in the United States, glutamine, 2 rriM; penicillin, 100 units/ml; and streptomycin, Switzerland, and Germany; and the academic community and 100 fig/ml). Cultures were gassed with 50% oxygen, 45% research institutes in America. The eventual goal is to develop nitrogen, and 5% CO?. The culture dishes were rocked at 35.5 a safe and effective pharmacological agent for prevention of to 36.0 degrees to allow the tracheas contact with both gas common forms of cancer in men and women, one which would and medium. All tracheas were maintained in medium contain be used as a chronic prophylactic measure to inhibit the ing no retinoid for the first 3 days. At the end of 3 days, some development of invasive cancer, much in the same manner in tracheas were harvested; almost all of these tracheas had which fluoride is used for prevention of dental caries. significant squamous metaplasia; in a set of several thousand Since the trachÃ©alorgan culture assay measures the intrinsic such cultures approximately 60% had keratinized lesions. The ability of retinoids to control epithelial cell differentiation (6, remaining tracheas were then divided into different groups which were then treated with either: (a) retinoid dissolved in 31), it is believed to have significant predictive value for the spectrograde DMSO2 (final concentration of DMSO in culture potential use of a new retinoid for prevention of epithelial medium was never greater than 0.1%) or (b) an equivalent cancer. Obviously, any in vitro test has dangerous liabilities for prediction of in vivo activity; in spite of these limitations, the amount of DMSO alone. Culture medium was changed 3 times trachÃ©alorgan culture assay is a most valuable procedure for a week, and all of the remaining tracheas were harvested at the end of 10 days in culture. Tracheas were fixed in 10% initial evaluation of the biological activity of a new retinoid. It is buffered formalin and embedded in paraffin. Cross-sections of an extremely sensitive assay and is used routinely to evaluate 5 jum were made through the midportion, stained with hema-

' To whom requests for reprints should be addressed. Received April 24. 1980; accepted July 2. 1980 2 The abbreviation used is: DMSO, dimethyl sulfoxide

OCTOBER 1980 3413

Downloaded from cancerres.aacrjournals.org on October 1, 2021. © 1980 American Association for Cancer Research. D. L. Newton et al. toxylin and eosin, and then scored with a microscope for the ides as inhibitors of carcinogenesis. Chart 10 shows 2 new presence of keratin and keratohyaline granules, both of which structures, in which both the ring and the side chain of the were found in approximately 90% of control cultures (in a set retinoid molecule have been modified. In these retinoids, a of several thousand such cultures) that had received no retinoid gem-dimethyl group has been inserted at position 4 of the for the entire 10-day culture period. Analogs were scored as cyclohexenyl ring and 2 aromatic rings have been introduced "inactive" if both keratin and keratohyaline granules were into the side chain; these new structures are intensely active. seen; they were scored as "active1 if neither keratin nor In view of the suggestion that 5,6-epoxyretinoic acid might be keratohyaline granules were seen. an activated form of retinoic acid (16, 29), this compound, as Retinoids. Retinoids were received in sealed ampuls, under well as 3 related analogs (5, 6-epoxyretinoic acid methyl ester, argon or nitrogen. These sealed ampuls were stored at -20Â° 5,6-epoxyretinyl acetate, and the 5,6-epoxy analog of retinyli- or below. Once opened, ampuls were stored in a vapor-phase dene dimedone), were tested (Chart 11). All of these epoxides nitrogen freezer. Stock solutions of retinoids were made in are significantly less active in the trachÃ©alorgan culture assay DMSO, at 0.1 to 1.0 mg/ml, and vials were stored in a vapor- than were their respective parent compounds. phase nitrogen freezer. After thawing, contents of a given vial The trachÃ©alorgan culture assay is highly specific for retinoid were used only once and then discarded. All work with retinoids structures. A wide variety of other terpenoid and related struc was performed under subdued light or in rooms with "gold" tures have been tested and been found to be inactive (data not fluorescent lamps. shown); these compounds include juvenile hormones I, II, and III; mycophenolic acid, and abscisic acid. Although /?-ionone RESULTS has not been tested, it is apparent that the side chain is of Charts 1 to 11 show the activity of 87 retinoids in the hamster major importance for biological activity, since the C,5 and C17 trachÃ©alorgan culture assay. Dose-response curves (19) were analogs of retinoic acid (Chart 3) are almost totally inactive, made for each retinoid, and the values derived for the dose and each of the 4 isomerie dihydroretinoic acid analogs (Chart effective in suppressing keratinization in one-half of the cul 3) is markedly less active than is all-frans-retinoic acid or its tures have been tabulated. All-frans-retinoic acid [50% effec methyl and ethyl esters. Similarly, the Ci8 ketone (Chart 8) was tive dose, 3 x 10~n M in a total of 1853 cultures (Chart 1)] totally inactive at 1 x 10~8 M. has been used as the reference substance. Most of the analogs in which the ring (Chart 2) or the side chain (Chart 3) has been DISCUSSION modified are significantly less active in the trachÃ©al organ culture assay. Retinol, retinyl acetate, and retinyl ethers (Chart The data shown in Charts 1 to 11 indicate that a very wide 4) are all less active than retinole acid, as are retinyl amine range of modifications in the ring, side chain, or polar terminus derivatives (Chart 5). A large number of retinal derivatives have of the retinoid molecule can be made and still allow expression been made, some of which have been useful in various biolog of biological activity. However, it is noteworthy that few analogs ical studies (3, 7, 25), but none are as active as retinole acid have been made that are more active than either all-frans- or in trachÃ©alorgan culture (Chart 6). In view of their relative ease 13-c/s-retinoic acid. In particular, we find no evidence that a of synthesis from either retinoyl chloride or retinoyl imidazole 5,6-epoxide is an activated form (16, 29), although such a and the appropriate amine, a particularly large number of amide molecule might require synthesis in situ in a cell in order to derivatives have been synthesized and tested (Chart 7). Deri- demonstrate enhanced biological activity. Similarly, both 4- vatization of the polar terminus of the retinoid molecule to form hydroxy- and 4-ketoretinoic acids, which are early products of amides offers the possibility of synthesizing a set of compounds oxidative metabolism of retinoic acid (8), were found to be with an especially wide range of chemical properties, including markedly less active than all-frans-retinoic acid. The possibility derivatives which have the interesting property of being soluble that retinoic acid might also be activated by epoxidation at the in both water and chloroform, as in the case of 2-retinamido- 9, 10 or 11,12 double bonds cannot presently be ruled out, ethyl sodium sulfate (Chart 7). Most of these compounds have since these compounds have not yet been definitively synthe appreciable activity in the 10~9 to 10"'Â° M range, with the sized and tested for biological activity. However, there is little notable exception of sterically hindered amides such as tert- or no evidence at present that any natural, known retinoid butyl retinamide or 1-methyl-3-hydroxypropyl retinamide, sug metabolite is more active in the trachÃ©alorgan culture assay gesting that, as a class, the amides must be hydrolyzed to than are either all-frans- or 13-c/s-retinoic acid. It is interesting retinoic acid before exerting their biological activity. Several of that in many other in vitro test systems retinoic acid has been the retinamides have been reported to be significantly less consistently more active than retinol, retinyl esters, or retinal toxic than is all-frans-retinoic acid and to be useful for inhibition (4, 14, 23, 27, 30). The correlations of activity of retinoids in of carcinogenesis in experimental animals (11, 18, 24). Other this trachÃ©alsystem with many other in vitro test systems are modifications of the polar terminus (Chart 8), particularly the excellent. Such test systems include reversal of changes in addition of 1 or 2 carbon atoms, have led to analogs in which duced by carcinogens in mouse prostate organ cultures (4, activity has been significantly diminished. 12), suppression of keratinization in chick skin organ cultures 13-c/s-Retinoic acid and several of its amide derivatives (30), inhibition of induction of ornithine decarboxylase in mouse (Chart 9) are highly active in trachÃ©al organ culture. It has skin (27, 28), inhibition of growth of murine melanoma cells recently been suggested (9) that isomerization of all-frans- (13, 14), enhancement of adhesion of transformed mouse retinoic acid to the 13-c/s- isomer may occur during physiolog fibroblasts (1), suppression of malignant transformation in a ical action of all-frans-retinoic acid. Newly synthesized 13-c/s- cloned mouse fibroblast cell line (3), and binding to cellular retinamides (Chart 9) are currently in initial stages of evaluation retinoic acid-binding proteins (26). It is of interest that the to determine if they will be more useful than all-frans-retinam- present trachÃ©alassay system gives a broader range of positive

3414 CANCER RESEARCH VOL. 40

Downloaded from cancerres.aacrjournals.org on October 1, 2021. © 1980 American Association for Cancer Research. Structure-Activity Relationships of Retinoids results than do some of the other test systems, particularly with 6. Clamon, G. H., Sporn, M. B., Smith, J. M., and Saffiotti, U. a- and /?-retinyl acetate reverse metaplasias of vitamin A deficiency in hamster trachea in amide derivatives, which show rather low activity in several organ culture. Nature (Lond.), 250. 64-66, 1974. other assays (1, 14, 23, 27, 30). Presumably, the trachÃ©al 7. Dickens, M. S.. Custer, R. P., and Sorof, S. Retinoid prevents mammary system has the enzymes necessary to hydrolyze retinamides; gland transformation by carcinogenic hydrocarbon in whole-organ culture. the low activity of a sterically hindered amide such as ferf-butyl Proc. Nati Acad. Sei. U. S. A. 76. 5891-5895, 1979. 8. Frolik, C. A., Roberts. A. B., Tavela, T. E . Roller, P. P., Newton. D.L., and retinamide is again noteworthy in this context. Finally, the Sporn, M. B. Isolation and identification of 4-hydroxy- and 4-oxo-retinoic intense activity of the retinoids in Chart 10 suggests that acid, in vitro metabolites of all-frans-retinoic acid in hamster trachea and liver Biochemistry, 18 2092-2097, 1979. chemical synthesis can provide new molecules which may have 9. Frolik. C A.. Roller, P. P.. Roberts, A. B., and Sporn. M. B. In vitro and in a stronger interaction with a receptor molecule or site than vivo metabolism of all-frans- and 13-c/s-retinoic acid in hamsters Identifi does all-frans-retinoic acid, in a manner analogous to the cation of 13-cis-4-oxoretinoic acid. J. Biol. Chem., in press. 1980. 10. Harisiadis, L., Miller, R. C.. Hall. E. J., and Borek, C. A vitamin A analogue enhanced binding of 9-a-fluoroglucocorticoids to hydrocorti- inhibits radiation-induced oncogenic transformation. Nature (Lond.), 274. sone receptors. 486-487, 1978. Although the successful use of retinoids for prevention of 11. Hixson, E. J.. and Denine. E. P. Comparative subacute toxicity of retinyl acetate and three synthetic retinamides in Swiss mice. J. Nati Cancer Inst., lethal cancer in men and women has yet to be demonstrated, 63. 1359-1364. 1979. recent developments in this field are highly encouraging. It is 12. Lasnitzki, I., and Goodman, D. S. Inhibition of the effects of methylcholanthrene on mouse prostate in organ culture by vitamin A and its analogs. by now well established that retinoids can prevent cancer of Cancer Res., 34: 1564-1571, 1974. the lung, bladder, breast, and skin in experimental animals (2, 13. Lotan, R., Giotta, G.. Nork, E., and Nicolson. G. L. Characterization of the 15, 18, 20, 21, 28); more recently, it has been shown in vitro inhibitory effects of retinoids on the in vitro growth of two malignant murine melanomas. J. Nati. Cancer Inst., 60. 1035-1041, 1978. that retinoids can directly suppress malignant transformation 14. Lotan. R., Neumann. G.. and Lotan. D. Relationships among retinoid struc of cells caused by chemicals, radiation, or viral transforming ture, inhibition of growth, and cellular retinole acid-binding protein in cultured factors (3, 10, 17, 25). Very low, nontoxic concentrations have S91 melanoma cells. Cancer Res.. 40: 1097-1102, 1980 15. Mayer, H , Bollag. W.. Hanni, R., and RÃ¼egg,R. Retinoids, a new class of been used in these experiments in cell culture, and these compounds with prophylactic and therapeutic activities in oncology and findings raise further hopes that retinoids will be valuable tools dermatology. Experientia (Basel), 34: 1105-1119, 1978. to provide needed understanding of the process of carcinogen- 16 McCormick. A. M . Napoli. J L.. Schnoes. H. K , and DeLuca, H. F. Isolation and identification of 5.6-epoxyretinoic acid: a biologically active metabolite esis, as well as a practical approach to the prevention of of retinole acid. Biochemistry. ; 7 4085-4090. 1978. 17. Merriman, R. L.. and Bertram, J. S. Reversible inhibition by retinoids of 3- disease. It remains to be determined whether the best approach methylcholanthrene-induced neoplastic transformation in C3H/10T'/Ã¯ CL8 to cancer prevention with new synthetic retinoids will involve a cells Cancer Res , 39 1661-1666. 1979. further increase in their intrinsic biological activity (as can be 18. Moon, R. C.. Thompson, H. J.. Becci, P. J., Grubbs. C. J . Gander. R. J.. measured with the present assay) or perhaps will involve a Newton. D. L., Smith, J. M.. Phillips, S. L., Henderson. W. R.. Mullen, L. T., Brown, C. C., and Sporn, M B. N-(4-Hydroxyphenyl)retinamide. a new further decrease in their intrinsic toxicity, as we have suggested retinoid for prevention of breast cancer in the rat. Cancer Res.. 39. 1339- elsewhere (22). 1346, 1979. 19. Sporn, M B.. Dunlop. N. M., Newton. D. L.. and Henderson. W. R. Relation ships between structure and activity of retinoids. Nature (Lond.). 263. 110- ACKNOWLEDGMENTS 113. 1976. We would like to express our appreciation to the following: Dr. John J. Burns, 20 Sporn. M B.. Dunlop. N. M . Newton. D. L.. and Smith, J. M Prevention of Dr. Willy Leimgruber, and Dr. Beverly A. Pawson (Hoffmann-La Roche Inc.); Dr. Chemical carcinogenesis by vitamin A and its synthetic analogs. Fed. Proc.. Werner Bollag (F. Hoffmann-La Roche & Co., AG); Dr. Robert J. Gander and Dr. 35. 1332-1338. 1976. Gavin Hildick-Smith (Johnson & Johnson); and Dr. Wolfgang Blechschmidt, Dr. 21. Sporn, M. B., and Newton, D. L. Chemoprevention of cancer with retinoids. Fed. Proc.. 38. 2528-2534. 1979. Fritz Frickel, Dr. Axel NÃ¼rrenbach, Dr. Joachim Paust, and Dr. Horst Pommer (BASF Aktiengesellschaft) for the immense help which all 3 of these companies 22. Sporn, M. B.. Newton. D. L.. Smith. J. M., Acton. N., Jacobson, A. R., and have provided to this testing program, for we have benefitted greatly not only Brossi, A. Retinoids and cancer prevention: the importance of the terminal from the large numbers of new retinoids which their laboratories have synthesized group of the retinoid molecule in modifying activity and toxicity. In: A. C. but also from the personal encouragement they have given to this testing Griffin and C R Shaw (eds ). Carcinogens: Identification and Mechanism of Action, pp. 441-453. New York: Raven Press, 1979. program; to Dr. Jerome Berson, Dr. Virgil Boekelheide. Dr. Arnold Brossi, Dr. 23. Strickland, S.. and Mahdavi, V. The induction of differentiation in teratocar- William Dauben, Dr. HarÃanGoering, Dr. Richard K. Hill, and Dr. William C. cinoma stem cells by retinoic acid. Cell, 75 393-403. 1978. Wildman for their generous advice and counsel on synthesis of retinoids; to Dr. Albert Kapikian, Dr. Gerald Clamon, Dr. John Bieri, Joseph Smith, Mary Baker, 24. Thompson, H. J.. and Becci. P. J. Inhibition of urinary bladder cancer in the and the late Betty Sanders for their advice and efforts in establishing the initial rat by retinoids. Proc. Am. Assoc. Cancer Res.. 20 96, 1979. organ culture assay; to Nancy Dunlop and Sandra Phillips for their assistance 25. Todaro, G. J., De Larco, J. E., and Sporn, M. B Retinoids block phenotypic with some of the assays: to Eli Lilly and Company and The Upjohn Company for cell transformation produced by sarcoma growth factor. Nature (Lond.) 2 76 272-274, 1978. providing the crystalline insulin and hydrocortisone hemisuccinate, respectively, which have been used in all assays; and to Ellen Friedman, Patricia Lewis, and 26. Trown, P. W.. Palleroni. A. V . Bohoslawec. 0., Richelo. B. N.. Halpern. J. Fred Mohney for their help with the preparation of this article. M . Gizzi, N.. Geiger. R., Lewinski, C., Machlin. L. J.. Jetten, A., and Jetten, M. E. R. Relationship between binding affinities to cellular retinoic acid- binding protein and in vivo and in vitro properties for 18 retinoids. Cancer REFERENCES Res., 4O: 212-220. 1980. 27. Verma, A. K., Rice, H M.. Shapas. B. G.. and Boutwell. R. K. Inhibition of 1 Adamo, S., De Luca, L. M , Akalovsky, !.. and Bhat, P. V. Retinoid-induced 12-O-tetradecanoylphorbol-13-acetate-induced ornithine decarboxylase adhesion in cultured, transformed mouse fibroblasts. J Nati Cancer Inst.. activity in mouse epidermis by vitamin A analogs (retinoids). Cancer Res., 62. 1473-1478, 1979 38. 793-801. 1978. 2. Becci, P. J.. Thompson. H. J., Grubbs, C. J.. Squire, R. A., Brown, C. C., 28. Verma, A. K.. Shapas. B. G., Rice. H. M.. and Boutwell, R K Correlation of Sporn, M. B , and Moon, R. C. Inhibitory effect of 13-c/s-retinoic acid on the inhibition by retinoids of tumor promoter-induced mouse epidermal urinary bladder carcinogenesis induced in C57BL/6 mice by W-butyl-A/-{4- ornithine decarboxylase activity and of skin tumor promotion. Cancer Res.. hydroxybutyDnitrosamine. Cancer Res , 38 4463-4466. 1978. 39. 419-425. 1979. 3. Bertram, J. S. Structure-activity relationships among various retinoids and 29. Wertz. P. W., Kensler, T. W., Mueller, G. C.. Verma. A. K., and Boutwell. R. their ability to inhibit neoplastic transformation and to increase cell adhesion K. 5.6-Epoxyretinoic acid opposes the effects of 12-O-tetradecanoyl-phor- intheC3H/10TV4CL8cell line. Cancer Res., 40: 3141-3146, 1980. bol-13-acetate in bovine lymphocytes. Nature (Lond.). 277. 227-229, 1979. 4. Chopra, D. P., and Wilkoff, L. J Reversal by vitamin A analogues (retinoids) 30. Wilkoff, L. J., Peckham, J. C., Dulmadge, E. A., Mowry. R. W., and Chopra, of hyperplasia induced by N-methyl-rV'-nitro-W-nitrosoguanidine in mouse D. P. Evaluation of vitamin A analogs in modulating epithelial differentiation prostate organ cultures. J. Nati. Cancer Inst. 58: 923-930, 1977. of 13-day chick embryo metatarsal skin expiants. Cancer Res.. 36. 964- 5. Clamon. G. H., Sporn, M. B., Smith. J M., and Henderson, W R. Effect of 972. 1976. o-retinyl acetate on growth of hamsters fed vitamin A-deficient diets. J 31. Wolbach, S. B . and Howe. P. R. Tissue changes following deprivation of Nutr., 105. 215-219, 1975. fat-soluble A vitamin. J. Exp. Med., 42: 753-777. 1925.

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Sources of retinoids were as follows: a, Nancy Acton and Arnold Brossi. National Institute of Arthritis. Metabolism and Digestive Diseases, Bethesda, Md.: b, BASF Aktiengesellschaft, Ludwigshafen am Rhein, Germany; c, Ralph S. Becker, University of Houston, Houston, Texas; d, F. Ivy Carroll, Research Triangle Institute, Research Triangle Park, N. C.; e. Marcia I. Dawson, SRI International, Menlo Park. Calif.; f, Clayton H. Heathcock, University of California, Berkeley, Calif.; g, Hoffmann-La Roche Inc., Nutley, N. J., and F. Hoffmann-La Roche & Co., AG. Basel, Switzerland; h, Johnson & Johnson, New Brunswick, N. J.; /, Koji Nakanishi, Columbia University, New York, N. Y.;/, Y. Fulmer Shealy, Southern Research Institute, Birmingham, Ala.; k, Steven C. Welch, University of Houston, Houston, Texas. ,, dose effective in suppressing keratinization in one-half of cultures.

Chart 1. Structure and activity of all-frans-retinoic acid and its esters. Chart 2. Structure and activity of ring-modified analogs of all-frans-retinoic acid and its esters. Chart 3. Structure and activity of side-chain-modified analogs of all-frans-retinoic acid and its esters. Chart 4. Structure and activity of all-frans-retinol, retinyl esters, and retinyl ethers. Chart 5. Structure and activity of all-frans-retinyl amine derivatives. Chart 6. Structure and activity of all-frans-retinal and derivatives. Chart 7. Structure and activity of all-frans-retinoic acid amides. Chart 8. Structure and activity of additional modifications of the polar terminus of the retinoid molecule. Chart 9. Structure and activity of 13-c/s-retinoic acid and derivatives. Chart 10. Structure and activity of ring- and side-chain-modified analogs of all-frans-retinoic acid and its esters. Chart 11. Structure and activity of 5,6-all-trans-epoxyretinoids.

1. AII-frans-Retinoic Acid and Retinole Acid Esters

COOR

(Number of Structure, R = Trivial Name Source ED^M Cultures) Retinoic acid, Tretinoin b,g 3x10~1 H (1853) Retinoic acid methyl ester g 3x 10~10 CH, (139) Retinoic acid ethyl ester g 5x10~10 C2H5 (124)

3416 CANCER RESEARCH VOL. 40

2. Ring-modified Analogs of All-frans Retinole Acid and its Esters

COOH (COOR')

of Structure, R : TrivialNamea/p/ja-Retinoic Cultures)(63)(45)

acid5,6-Dihydroretinoic x10~8<1 a acidSource99EDuo.M<1 x IO'9(Number '7 5,6-Dihydroxyretinoic acid 2 x IO (12) OH methyl ester R'=Me

4-Hydroxyretinoic acid 7 x 10~10 (43)

OH 7 x IO'10 4-Ketoretinoic acid g (35)

1 x IO'6 Phenyl analog of retinoic (29) Acid

4-Methoxy-2,3,6- 5 x 10--9 (228) trimethylphenyl analog of CH30 retinoic acid; TMMP analog of retinoic acid 2 x IO'8 4-Methoxy-2,3,6- (92) trimethylphenyl analog of CH30 retinoic acid ethyl ester; R'=Et TMMP analog of retinoic acid ethyl ester; Etretinate

4-Hydroxy-2,3,6- Inactive, 12/13 (22) trimethylphenyl analog of cultures, HO 1 x 10 -7 R'=Et retinoic acid ethyl ester

5 x 10~10 Dimethylacetyl cyclopen- g (103) tenyl analog of retinoic acid COCH3

OCTOBER 1980 3417

2. Ring-modified Analogs of All fra/7s-Retinoic Acid and its Esters (Cont'd)

(Number of Structure, R = Trivial Name Source '50' M Cultures)

2 x 10~10 Dimethylmethoxyethyl (81) cyclopentenyl analog of retinole acid CHCH3 I OCH3

2-Furyl analog of retinoic Inactive, 10/13 (27) acid cultures, 1 x 10-6

3-Thienyl analog of retinoic x 10'8 (23) acid

3-Pyridyl analog of retinoic 3 x 10 -7 (22) acid

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3. Side Chain-modified Analogs of All-framr Retinoic Acid and its Esters

(Number of Structure, R = Trivial Name Source Cultures)

5 x 10~10 COOH 7,8-Dehydroretinoic acid (26)

1 x 10 8 COOH 7,8-Dihydroretinoic acid (53)

10~7 COOH 9,10-Dihydroretinoic acid g (53)

11,12-Dihydroretinoicacid g IO (40) methyl ester

~8 -COOC2H5 13,14-Dihydroretinoic acid 3 x 10 (47) ethyl ester

COOH Ci5 analog of retinole acid Inactive, (13) 7/7 cultures, 1 x 10~6M

â€¢COOH Ci7 analog of retinole acid Inactive, (12) 6/6 cultures, 1 x 10 8M

â€¢COOH C22analog of retinoic acid c, g 3 x 10 (17)

2 x IO"10 COOH Aryltriene analog of retinoic e (24) acid (trans)

10~9 Aryltriene analog of retinoic e (11) acid ids)

COOH

OCTOBER 1980 3419

4. AII-frans-Retinol, Retinyl Esters, and Retinyl Ethers

.x^^v.^^CHnOR^Â«X^ x^A,XxVTrivial^s^X(Number

of Structure, R = NameRetinolâ€¢^^ Cultures)b.gSource EOgg.M

H (83)Retinyl 7>1010

COCH3 (152)Retinylacetate b.g 1 x 10 9

CH3 (134)Retinylmethylether b.g 3x1Q-9

C4H9 (71)Retinylbutyl ether b, g 3 > 10"8

phenyl5. (31)Vmine g 8 > 10'8

AII-frans-RetinylATrivial Derivatives(Number

of Structure. R1=, R2: Cultures)/V-AcetylNameether Source EDg^M (113)/V-Benzoylretinyl amine b.g 9x10"9 H, COCH3 (61)/V-Methylretinyl amine b 2x 10~9 H, COC6H5 /V-acetyl retinyl d >1x10"9 (35) CH3, COCH3 amine

-9 CH3, COC6H5 N-Methyl /V-benzoyl retinyl 1x10 (30) amine

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6. AII-fra/JS-Retinal and Derivatives

CH = R

of Structure, R = TrivialNameRetinalRetinal ED^.Mb,g Cultures)(98)(54)(61)(86)(12)(14)(29) -10g 3 x 10 O 10~10g 4 x NNHCOCH3 acetylhydrazoneRetinal

NOH oxime3-Retinylidene-2,4- 8a 1 x 10 IO"9a 2 x C(COCH3)2 pentanedione; retinylidene acetylacetone4-Retinylidene-3,5- IO"9a 4 x C(COCH2CH3)2 heptanedione5-Retinylidene-4,6-

C(COCH2CH2CH3)2 Inactive, nonanedione2-Retinylidene-1,3- 6/7 cultures 10~8Ma 1 x

.COCH2 Inactive, cyclopentanedioneSource 16/17 cultures 1 x 1Q-8M(Number

1 x IO'10 2-Retinylidene-1,3- (107) cyclohexanedione

2 x 10- 10 ,COCH2 CH3 2-Retinylidene-5, 5-dimethyl (150) 1,3-cyclohexanedione; "COCH^ XCH3 Retinylidene dimedone

,COCH2CH2 2-Retinylidene-1,3- 4 x 10 (51) cycloheptanedione â€¢COCH2CH2I

2-Retinylidene-1,3- 2 x 10 10 (37) cyclooctanedione

(36) 2-Retinylidene-1,3- 2 x 10 10 cyclononanedione VCOCH2CH2CH2

OCTOBER 1980 3421

AcidPKjX^X^/H^^^AII-fra/7S-Retinoic

^^^^w^^x^Structure,

of NameC2H5 R = Trivial ED^.Mg Cultures)(86)(62)(39)(22)(68)(22)(21)(22)(40)(41)(31)(60)(55)(77)(41)RESEARCH

retinamiden-C3H7 /V-Ethyl IO'9g,h 1 x

retinamideA7-C4H9 /V-Propyl 2x10-10g,

retinamidef-C4H9 /V-n-Butyl h7x10-10h

retinamide2-C2H4OH /V-f-Butyl 10-8g,h > 1 x

/V-2-Hydroxyethyl 10'10b 1 x retinamide2-C3H6OH

A/-2-Hydroxypropyl 3x1Q-10b retinamide3-C3H6OH

A/-3-Hydroxypropyl 2x10-10b retinamide2,3-C3H5(OH)2

/V-2,3-Dihydroxypropyl 2xlQ-10b retinamideCH(CH3)CH2CH2OH

AM-Methyl-3-hydroxypropyl 10-9b > 1 x retinamide4-n-C4H8OH

/V-4-Hydroxybutyl 2x1Q-10g, retinamideC6H5

retinamide2-C6H4OH /V-Phenyl h4x10"10â€žh

/V-2-Hydroxyphenyl retinamide3-C6H4OH

/V-3-Hydroxyphenyl 3x1Q-10*h retinamide4-C6H4OH

/V-4-Hydroxyphenyl retinamide4-C6H4OCOC4H9

/V-4-Pivaloyloxyphenyl 2x1Q-10CANCER(Number retinamide3422Amides^^CONHRSource

VOL. 40

7. AII-fra/is-Retinoic Acid Amides (Cont'd)

of Structure, R = TrivialNameA/ SourceCultures)b EDg,, M

(57)b <1x1Q-10 2-C6H4COOH 2 Carboxyphenyl retinamide/V-3-Carboxyphenyl

3-C6H4COOH (42)b 1 x 10'10 retinamide/V-4-Carboxyphenyl

4-C6H4COOH (70)b 1 x IO"10 retinamide/V-5-Tetrazolyl

(65)e < 1 x IO'10 CN4H retinamide/V-2-Retinamidoethyl

CH2CH2OS03Na (14)olar 2x10-10 sulfate8. sodium

Additional Modifications of the P Terminus Moleci\X^sTrivialof the Retinoid ule(Number

of Structure, R = NameAxerophtheneRetinyl Cultures)bSource ED^.M

CHCH3 (86)b 2 x 10 9

(11)b >1 x IO"8 CHCH2CH3 methane; 15-Methylaxerophthene14-Methyl

(12)/ >1 x 10-8 C(CH3>2 axerophtheneMethyl

(37)a 2 x IO'7 CHCOCH3 retinone15-Dimethyl

CHC(CH3)2OH retinolRetinyl (9)k >1 x 10 8

(13)c >1 x IO'8 CHCH2SCOCH3 thioacetateC18

O Ketone(Number Inactive, 8/8 (8) cultures, 1 x 10-8M

OCTOBER 1980 3423

(Number of Structure, R = Trivial Name Source ED^. Cultures)

OH 13-cÂ«-Retinoicacid; b.g 3 x 10 (69) Isotretinoin

x 10-10 NH(C2H5) /V-Ethyl 13-c/s-retinamide ii3 3 x 10-10(37) NH(2-C2H4OH) /V-2-Hydroxyethyl 13-c/s- (40) retinamide 1 x io~10 NH(2,3-C3H5[OH]2) A/-2,3-Dihydroxypropyl (29) 13-c/s-retinamide

10~9 NH(4-C6H4OH) /V-4-Hydroxyphenyl (88) 13-c/s-retinamide

2 x 10--10 NH(CN4H) N-5-Tetrazolyl 13-c/s- (63) retinamide

10. Ring- and Side Chain-modified Analogs of AII-frans-Retinoic Acid and its Esters

COOR

(Number of Structure, R = Trivial Name Source ED^.M Cultures) g 1 x IO"11 H Ro 13-7410 (50)

Ro 13-6298 1 x 10~11 C2H5 9 (80)

3424 CANCER RESEARCH VOL. 40

11. 5,6-AII-fra/?s-Epoxyretinoids

(Number of Structure. R = Trivial Name Source E ^ M Cultures)

g 2 x 10 9 COOH 5,6-Epoxyretinoic acid (44)

COOCH3 5,6-Epoxyretinoic acid k 3 x 10 9 (45) methyl ester

CH2OCOCH3 5,6-Epoxyretinyl acetate k 4 x 10 9 (35)

CH(C8H1002) 5,6-Epoxide of a 3 x 10 9 (46) retinylidene dimedone

OCTOBER 1980 3425

Dianne L. Newton, William R. Henderson and Michael B. Sporn

Cancer Res 1980;40:3413-3425.

Updated version Access the most recent version of this article at: http://cancerres.aacrjournals.org/content/40/10/3413

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