Early Stages of 1,2-Dimethylliydrazine-Induced Colon Carcinogenesis Suppress Immune-Regulated Ion Transport of Mouse Distal Colon1
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[CANCER RESEARCH54, 5930—5936,November15, 19941 Early Stages of 1,2-Dimethylliydrazine-induced Colon Carcinogenesis Suppress Immune-regulated Ion Transport of Mouse Distal Colon1 Russell R. Broaddus, Michael J. Wargovich, and Gilbert A. Castro2 Departments of Physiology and Cell Biology (R. R. B., G. A. C.] and Medical Oncology [M. J. WI, University of Texas Medical School [R. R. B., G. A. C.] and University of Texas M. D. Anderson Cancer Center [M. .1. WI, Houston, Texas 77225 ABSTRACT then to adenocarcinoma. In addition to these genetic events, epige netic and microenvironmental changes also contribute to the devel Genetic events, such as gene deletion, mutation, and amplification, are opment of neoplasia (3). For colon cancer, these latter changes have involved in the development and progression of colonic neoplasia The importance of interactions between immune cells and neoplastlc cells in been much less intensively studied. influencing the pathogenesis of colon cancer is suggested by the clinical Compelling results suggest that local mucosal immunity is one such efficacy of levamisole, an immunostimulant, in the treatment of colon microenvironmental factor important in the pathogenesis of colorectal cancer and by the association of local lymphocytic infiltration with Im carcinoma. Colon adenocarcinomas often contain an inflammatory proved prognosis. Thus, the immune cell-neoplastic cell interaction can be infiltrate, typically consisting of T lymphocytes with some macro viewed as being analogous to various host-parasite relationships that phages and B lymphocytes (4). The presence of lymphocytic infiltra involve the immune system attempting to contain the intruding parasite tion or of lymphoid follicles near resected colon cancers is associated on the one hand and the parasite attempting to escape detection and with an increased patient survival rate (5, 6). Levamisole, a nonspe rejection on the other. This study is an attempt to gain a better under standing ofsuch interactions by examining possible effects ofa developing cific stimulator of many different arms of the immune system, in tumor on the immune system. Colon cancer was experimentally induced in combination with 5-fluorouracil significantly improves disease-free mice to examine potential effects of carcinogenesis in the colon on local survival and overall survival in patients with Stage C resected colon mucosal immune function in situ, using the expression of type I hyper cancer (7). These observations underscore a delicate modulatory role sensitivity as an index of immune function. Antigen-induced changes in of the immune system, especially the mucosal immune system of the net ion transport, a quantifiable correlate of type I hypersensitivity, were colon, in colonic neoplasia. To enhance an understanding of the measured in the colon of mice following the administration of the procar interaction between the mucosal immune system and neoplastic tissue, cinogen 1,2-dimethyihydrazine (DM11).Segments of colon and small in we investigated the effects of experimental colon carcinogenesis on testine from mice immunized by infection with Trichinella spiralir secrete immunity in the colon and small intestine. ions, manifested as a rise in transmural short-circuit current, when dial lenged with T. spiralis antigen in Ussing chambers. Antigen-induced rise in Systemic administration of the procarcinogen DMH3 to CF-i mice transmural short-circuit current Is mast cell dependent and occurs only in is a well-established laboratory model of colon carcinogenesis. DMH immunized mice. To determine the effects of early stages of colon card selectively induces colonic adenomas and adenocarcinomas (8, 9) nogenesis on this mucosal immune response, mice were immunized with T. while only rarely causing liver or small intestine tumors (10). Admin spiralis prior to and after 6 weekly injections of DM11. Responsiveness to istration of DMH causes a continuum of morphological changes from antigenic challenge was suppressed in the distal colon 4—6weeks after the normal colonic epithelium to carcinoma. One injection of DMH final injection of DMH. Although responsiveness to antigen was sup causes the development of aberrant crypts within 2 weeks (11), while pruned, the colonic epithelium remained sensitive to direct stimulation by 6 injections of DMH, 1 per week for 6 weeks, typically causes grossly exogenous secretagogues. Decreased antigen responsiveness observed In visible adenomas and carcinomas of the colon within 4—6months (8, the distal colon was not due to generalized Immunesuppression by DM11, because the proximal colon and thejejunum retained their responsiveness 9). Within the same time frame as the histological development of to antigen, and immune rejection of a secondary T.spiralis infection from aberrant crypts, there is electrophysiological evidence of inhibition of the small Intestinewas not altered. Visible tumors eventually developed 30 the Na@-K@-ATPase(12) and stimulation of Na@-H@exchange (13) in weeks after the final Injection of DM11 only in the distal portions of the the distal colon. These changes in ion transport are important, because colon. These results suggest that early stages of DM11-induced carcino Na@influx into the cell (14) and increased intracellular pH (15) are genesis are associated with the suppression of mucosal immune function, early events in mitogenesis and may, at least partially, be the basis for as measured by Immune-regulatedion secretion, in the distal colon but not the hyperproliferation observed in aberrant crypts (16). in the proximal colon or jejunum. Future eluddation of the mechanisms The hyperproliferative lesions, aberrant crypts, adenomas, and ad by which this localized hnmunosuppression occurs may provide clues to enocarcinomas of the colon induced by DMH are biologically and the microenvironmental changes necessary for tumor progression in the histologically quite similar to those seen in humans (17). Importantly, distal colon. there is pathological evidence that DMH-induced colon tumors (18) resemble human tumors (2) in that both follow an adenoma-to INTRODUCTION carcinoma sequence. Because of the potential progression of early Recent molecular biological evidence (1) supports histological ev changes to malignancy, the study of the premalignant hyperprolifera idence (2) indicating an adenoma-to-carcinoma sequence in the de tive lesions and aberrant crypts is crucial in understanding the patho velopment of colon cancer. The accumulation of mutations in onco genesis of colon cancer. genes and deletions and mutations of tumor suppressor genes allows Immunity in the small intestine and colon of DMH-treated mice for the progression of hyperproliferative epithelium to adenoma and was measured by quantifying a vital physiological function, ion trans port, that is regulated by the mucosal immune system (19). Immune Received 6/14/94; accepted 9/20/94. regulated intestinal ion transport has been described for a variety of The costs of publication of this article were defrayed in part by the payment of page host-antigen systems. Antigenic challenge of intestinal segments from charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1 This work was supported by NIH Grant P01-DK37260 and the University of 3 The abbreviations used are: DMH, 1,2-dimethylhydrazine; PGE@, prostaglandin E@; Texas-Houston Health Science Center Mucosal Biology Program. 5-rn,,5-hydroxytryptamine;L@short-circuitcurrent;KRBbuffer,Krebs-Ringerbicar 2 To whom requests for reprints should be addressed, at Department of Physiology and bonate buffer; TGF-@, transforming growth factor @;cAMP, cyclic AMP; cGMP, cyclic Cell Biology, University of Texas Medical School, P.O. Box 20708, Houston, TX 77225. GMP. 5930 Downloaded from cancerres.aacrjournals.org on September 26, 2021. © 1994 American Association for Cancer Research. COLONCARCINOGENESISSUPPRESSESMUt@OSALIMMUNEFUNCI1ON laboratory rodents sensitized to dietary proteins (20, 21) or parasites Segments of intestine were allowed to stabilize for 30 mm after @ (2Z 23) resultsin an immediate(typeI) hypersensitivityreaction, mounting in the chambers to obtain a steady-state [email protected] basal is expressed as net epitheial anion secretion. In Ussing chambers, net an index of net active ion transport across the serosal and mucosal anion secretion is manifested electrophysiologically as a rise in trans surfaces. The tissues were stimulated with antigen or secretagogues mural I.e. Applying similar principles, we have recently described a added to the serosal bathing fluid. T. spiralis antigen was added at a method to quantify colonic mucosal immune function in situ (24). concentration of 50 ,.agprotein/mi of Ussing chamber fluid. PGE@and Briefly, segments ofcolon from mice immunized by infection with the 5-HT were added at final chamber concentrations of iO@ M and 10@ intestinal nematode parasite Trichinella spiralis undergo an increase M, respectively. After addition of antigen or secretagogue, the maxi in Inc (biI,,@)after challenge with T. spiralis-derived antigen in Ussing mum change in I@ (@M@)from the basal state was calculated and chambers. The antigen-induced AL@is inhibited by furosemide, indi expressed as @ eating that the is most likely due to net Cl@secretion by the colon. T.spiralisantigenbridges1gBboundto mucosalmastcells,triggering Histology the release of anaphylactic mediators that stimulate epitheial ion secretion. Ion secretion