Project description:The incidence and mortality rates of prostate cancer are significantly higher in African-American men when compared to European-American men. We tested the hypothesis that differences in tumor biology contribute to this survival health disparity. Using microarray technology, we obtained gene expression profiles of primary prostate tumors resected from 33 African-American and 36 European-American patients. These tumors were matched on clinical parameters. We also evaluated 18 non-tumor prostate tissues from 7 African-American and 11 European-American patients. The resulting datasets were analyzed for expression differences on the gene and pathway level comparing African-American with European-American patients. Our analysis revealed a significant number of genes, e.g., 162 transcripts at a false-discovery rate less than 5%, to be differently expressed between African-American and European-American patients. Using a disease association analysis, we identified a common relationship of these transcripts with autoimmunity and inflammation. These findings were corroborated on the pathway level with numerous differently expressed genes clustering in immune response, stress response, cytokine signaling, and chemotaxis pathways. Furthermore, a two-gene tumor signature was identified that accurately differentiated between African-American and European-American patients. This finding was confirmed in a blinded analysis of a second sample set. In conclusion, the gene expression profiles of prostate tumors indicate prominent differences in tumor immunobiology between African-American and European-American men. The profiles portray the existence of a distinct tumor microenvironment in these two patient groups. Experiment Overall Design: A total of 69 fresh-frozen prostate tumors were obtained from the NCI Cooperative Prostate Cancer Tissue Resource (CPCTR) and the Department of Pathology at the University of Maryland (UMD). All tumors were resected adenocarcinomas that had not received any therapy prior to prostatectomy. The macro-dissected CPCTR tumor specimens (n = 59) were reviewed by a CPCTR-associated pathologist, who confirmed the presence of tumor in the specimens. These tissues were collected between 2002 and 2004 at four different sites, with each site providing tissues from both African-American and European-American patients. Information on race/ethnicity (33 African-Americans and 36 European-Americans) was either extracted from medical records (CPCTR) or obtained through an epidemiological questionnaire in which race/ethnicity was self-reported (UMD). Only one patient, a European-American, was also Hispanic. Surrounding non-tumor prostate tissue was collected from 18 of the recruited patients in this study. Of those, 7 were African-American men and 11 were European-American men. We also isolated total RNA from 10 needle biopsy specimens collected from patients at the National Naval Medical Center (one African-American and 9 European-Americans) that did not have prostate cancer. From those, we prepared two RNA pools, each representing 5 patients. Clinicopathological characteristics of the patients, including age at prostatectomy, histology, Gleason score, pathological stage, PSA at diagnosis, tumor size, extraprostatic extension, margin involvement, and seminal vesicle invasion were obtained from CPCTR. For UMD cases, this information was extracted from the medical and pathology records, if available. Written informed consent was obtained from all donors. Tissue collection and study design were approved by the institutional review boards of the participating institutions.

Project description:Prostate cancer incidence and related mortality are disproportionately higher in African American (AA) men than European American (EA) men, but the molecular mechanisms contributing to racial disparities are not fully elucidated. To identify molecular factors that can contribute to disease biology in prostate cancer from AA and EA men, we utilized a multi-omics approach to measure and integrate DNA methylation with gene expression changes. We compared and contrasted results from adjacent non-tumor and tumor tissues from AA and EA men. We found that hypermethylated regions are enriched for PRC2 and H3K27me3 pathways and EZH2/SUZ12 cofactors in a race-independent manner. On the other hand, hypomethylated regions in prostate tumors from AA men were enriched for olfactory/ribosomal pathways as well as distinct cofactors such as CTCF and KMT2A. DNA methylation at transcription start sites and 5’-UTR at GATA3, an androgen receptor (AR) coregulator, is associated with decreased gene expression in prostate tumors of AA men. Our analysis also showed an inverse correlation between DNA methylation and RNA expression of AR transcriptional targets, such as TRIM63, in prostate tumors of AA men. Our observations suggest a dysregulation of the AR signaling pathway in prostate cancer from AA men. To determine whether targeting AR results in race-specific gene expression changes, we utilized a prostate-cancer-specific Boolean network. Our simulation revealed that prolonged AR inhibition results in significant dysregulation in TGF-β, IDH1, and cell cycle pathways in prostate cancer of AA men. We expanded our observation of gene expression changes in the Boolean network and investigated RNA-sequencing data to better understand overall transcriptional alterations occurring in prostate tumors from AA and EA men. We found that gene expression changes related to microtubules, a subset of immune-related, and TMPRSS2-fusion pathways were dysregulated in prostate tumors of AA men and corresponded with progression-free survival of AA men. Altogether, the current study dissects complex signaling networks that are clinically actionable in prostate cancer from AA and EA men.

Dataset Information

1,25-Dihydroxyvitamin D3 Suppresses Prognostic Survival Biomarkers Associated with Cell Cycle and Actin Organization in a Non-Malignant African American Prostate Cell Line

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