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Tamoxifen-associated endometrial tumors expose differential enhancer activity for Estrogen Receptor alpha [ChIP-Seq]

ABSTRACT: Tamoxifen, a small molecule inhibitor that binds the Estrogen Receptor alpha (ERα), blocks breast cancer progression while increasing the risk for endometrial cancer. In this study, we assessed genome-wide ERα-chromatin interactions in surgical specimens of endometrial tumors from patients who were previously treated for breast cancer with tamoxifen, and endometrial tumors from patients who were treated without tamoxifen. We compared ERα and signal at differential ERα sites in endometrial tumors of nine patients who received tamoxifen with endometrial tumors with six patients who never used tamoxifen. In addition, we performed H3K27ac (a marker for activity) ChIPs on the above mentioned endometrial tumors, and assed this signal at differential ERα sites. Compared to endometrial tumors of non-users, tamoxifen-associated endometrial tumors exposed higher H3K27ac intensities at ERα sites that are enriched in tamoxifen-associated endometrial tumors. Four tamoxifen-associated endometrial tumors that we used in our analysis have been previously published as Tumor A, B, D, and E in GSE81213.

ORGANISM(S): Homo sapiens

PROVIDER: GSE94031 | GEO | 2017/03/06

SECONDARY ACCESSION(S): PRJNA363085

REPOSITORIES: GEO

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Project description:Full title: comparison of the genomic (arrayCGH) profiles of endometrial cancer with and without prior prolonged tamoxifen treatment for primary breast cancer Purpose: Tamoxifen has been a very effective treatment for breast cancer for several decades, however, at the same time increases the risk of endometrial cancer, especially after prolonged exposure. In addition, tamoxifen has been associated with a higher proportion of unfavorable uterine tumor subtypes (carcinosarcomas and serous adenocarcinomas) with worse survival. We investigated whether endometrial tumors, which developed after prolonged tamoxifen treatment for breast cancer, are genetically different from endometrial tumors without preceding tamoxifen exposure. Experimental design: Array CGH was used on archival formalin-fixed paraffin embedded (FFPE) endometrial tumors to determine genomic aberrations. We compared the genomic profiles of 52 endometrial tumors from breast cancer patients after long-term (>=2 years) tamoxifen use (endometrioid adenocarcinomas n=26, carcinosarcomas n=14 and serous adenocarcinomas n=12) with endometrial tumors from unexposed breast cancer patients (n=45). Genomic profiles were correlated with tamoxifen exposure, tumor subtypes and histopathological characteristics of the endometrial tumors. Results: The common uterine corpus cancers of the endometrioid subtype show few genomic aberrations. Tumors with many genomic aberrations were in general ER-negative. In contrast, carcinosarcomas and serous adenocarcinomas showed many aberrations, however they were indistinguishable from each other. Tumors that developed after prolonged tamoxifen use did not show more or different aberrations than unexposed tumors. This was true for all tumor subtypes. Conclusion: Endometrial carcinomas that develop after prolonged tamoxifen use can not be distinguished from non-users on basis of their tumor genomic profile. 52 endometrial tumors from breast cancer patients after long-term (>=2 years) tamoxifen use (endometrioid adenocarcinomas n=26, carcinosarcomas n=14 and serous adenocarcinomas n=12) and 45 endometrial tumors from unexposed breast cancer patients