ICANCER RESEARCH 58. 2278-2281. June I. IWK] Advances in Brief Genomic Changes in Endometrial Polyps Associated with Tamoxifen Show No Evidence for Its Action as an External Carcinogen1 Paola Dal Cin, Dirk Timmerman, Ivo Van den Berghe, Sylke Wanschura, Bernd Kazmierczak, Ignace Vergole, Jan Deprest, Patrick Neven, Philippe Moerman, JörnBullerdiek, and Herman Van den Berghe2 Center fur Human Genetics IP. D. C.. H. V. d. B.I and Departments of Obstetrics and Gynecology ¡D.T.. I. V.. J. D.I and Pathology ¡I.V.d. B„P. M.¡.University of Leuven, MKK) Leuven. Belgium; Department of Obstetrics and Gynecology, St. Jans-iekenhuis, B-IÃoeOOBrussels, Belgium ¡P.NJ; and Center for Human Genetics and Genetic Coniiseli University of Bremen, D-28359 Bremen. Germany ¡S.W.. B. K., J. B.I B- Abstract Eighty-eight cndometrial specimens from 36 postmenopausal breast cancer patients treated with tamoxifen were investigated cytogenetically and molecularly using fluorescence in situ hybridization with appropriate probes for the HMGIC and HMCIY senes. Twenty control specimens, 10 endometrial polyps, and 10 endometrial biopsy specimens were investi gated in the same way. Of the 88 specimens, 44 were from endometrial polyps; 3 were from endocervical polyps; 7 were from cystic endome- trium; 30 were from normal or atrophie endometrium, normal endocer- vix, or myonietrium; and 4 were from endometrial carcinomas. Chromo some investigation of the endometrial polyps showed the nature of the chromosome changes in tamoxifen-induced polyps to be the same as that in the controls and in sporadic endometrial polyps described in the literature. HMGIC and HMGIY gene rearrangements in both groups were identical as shown by fluorescence in situ hybridization, which also al lowed for the detection of seven hidden paracentric inversions involving I2ql5, one of which occurred in a cystic endometrium. The carcinomas did not exhibit any of these changes. Because abnormal expression of HMGIC or IlMtïn as a consequence of structural chromosome changes in 12ql5 or 6p21, respectively, is invariably associated with benign neoplasia, tamoxifen-associated endometrial polyps are unlikely to undergo further malignant transformation, and a mode of action of tamoxifen as an external carcinogen is unlikely. Introduction Tamoxifen is a nonsteroidal triphenylethylene derivative that has been widely used in the treatment of breast cancer since the 1970s. It blocks the growth-promoting effects of estrogens in breast tissue, mainly through competitive inhibition of the estrogen receptor mech anism ( 1). In addition, an estrogenic effect on the endometrium has been described, resulting in a variety of endometrial changes ranging from endometrial hyperplasia to polyps and endometrial cancer (2-4). Most sporadic endometrial polyps present discernable genomic changes. Cytogenetic investigations demonstrated that different spe cific chromosome rearrangements can be observed despite a seem ingly identical clinical and morphological appearance. Besides a nu merically important group with a normal karyotype, three major cytogenetically abnormal subgroups have been identified involving the 6p21, I2ql5, and 7q22 regions (5). These chromosome abnormal ities led to the discovery of underlying molecular rearrangements and to partial elucidation of the mechanisms of tumorigenesis by abnormal Received 2/17/98; accepted 4/17/98. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore he hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. 1This article presents research results of the Belgian program on Interuniversity Poles of Attraction initiated by the Belgian Stale, Prime Minister's Office. Science Policy Programming. The scientific responsibility is assumed hy its authors. " To whom requests for reprints should be addressed, at Center for Human Genetics. University of Leuven. Herestraat 49. B-3000 Leuven. Belgium. Phone: 32-16-34-58-78: Fax: 32-16-34-59-92. expression of the HMGIC and HMGIY genes in endometrial polyps with 12q and 6p anomalies, respectively (6-8). Because the frequency of endometrial polyps significantly in creases among tamoxifen-treated patients (9, 10), we investigated these endometrial changes cytogenetically and molecularly to exam ine whether the same genomic changes were present in the tamoxifen- related tumors as those known to occur in endometrial changes unrelated to tamoxifen. Materials and Methods Patients and Clinical Data. Transvaginal ultrasonography combined with sonohysterography. when necessary, was the technique used in our monitoring of the uterus in 36 tamoxifen-treated postmenopausal breast cancer patients (some clinical data are summarized in Table 1; Ref. 11). Suspected endometrial lesions were resected together with a randomly taken endometrial biopsy. Part of each specimen was processed for pathological investigations, and the remaining tissue was used for cytogenetic analysis. For the purpose of this study, endometrial polyps as well as normal-looking endometrium from 10 patients who were not treated with tamoxifen were resected and used as controls. A total of 88 specimens from tamoxifen-treated patients were studied cytogenetically (Table 2) in addition to 20 specimens from the control population. Cytogenetic and Molecular Cytogenetic Investigations. G-banded met- aphases were obtained after short-term culture of an overnight disaggregated specimen of each sample according to routine methods. At least 20 metaphases were analyzed in each tissue sample. FISH' was performed after GTG-banding of the same metaphase spreads according to the procedure described by Kievits et al. (12). Metaphases were hybridized with a pool of cosmids 27EI2 and 142HI flanking the third intron of the HMGIC gene mapped at 12ql5 (6) and a PAC clone containing the HMGIY gene located at 6p21.2 (13), respectively. Slides were analyzed using a Zeiss Axioplan fluorescence microscope (Zeiss, Oberkochen, Germany). Results were processed and recorded with the Power Gene Karyotyping System (Perceptive Scientific Instruments; Halleddale, United Kingdom). In translocations affecting HMGIC or HMGIY. split signals were observed on the derivative chromosome 12 or 6, respectively, and on the translocation chro mosome partners. In the case of pericentric or paracentric inversion of chro mosome 12 or 6. split signals on the short and the long arm or a double signal on one arm, respectively, were observed on those chromosomes. In cases without an intragenic break in the HMGIC or HMGIY genes, the signal was not found to be split in its original site or on the translocation partner. Results Pathology Findings. Of the resected endometrial lesions from tamoxifen-treated patients (88 specimens), 44 specimens were diag nosed as endometrial polyps, whereas 3 specimens were endocervical polyps. Results of the histológica! investigation of the 41 other spec imens are found in Table 2. Ten samples of normal-looking endometrium from control patients 'The abbreviations used are: FISH, fluorescence in situ hybridization; PAC, PI artificial chromosome. 2278 Research. on February 28, 2016. © 1998 American Association for Cancer cancerres.aacrjournals.org Downloaded from