Abstract 7645: Differentially expressed genes as prognostic markers in racial disparities of prostate cancer
Authors: Ahmed Amel A. , Verma Shiv , Atawia Ibrahim M. , Shen Daniel L. , MacLennan Gregory T. , Fu Pingfu , Gupta Sanjay 
Published: March 2024

Abstract
Racial disparities in prostate cancer are prevalent, with African American (AA) men experiencing 60% greater incidence and 2 to 3 times higher mortality than Caucasian American (CA) men. Consequently, there is a pressing need for improved means of interrogating race/ethnicity-based prostate cancer biology in order to identify biomarkers to help stratify men at high-risk for prostate cancer-specific progression and death and offer treatment recommendation that would mostly benefit AA men undergoing early aggressive therapies. Current predictive models rely on clinical variables but do not account for these disparities. The overall goal is to construct a race-specific prostate cancer prognostic prediction model for risk assessment. Here we performed comprehensive bioinformatics analysis using the data from 17 pairs of gene expression array from AA and CA cohorts and identified 63 differentially expressed genes (DEGs) by race. Among them, chemokine receptor 4 (CXCR4), viz. p-Akt (Ser473), fatty acid synthase (FASN), interleukin-6 (IL-6) and matrix metallopeptidase 9 (MMP-9) gene expressions were significantly altered in AA groups. Immunohistochemistry was performed on 163 prostate cancer patient specimens to validate DEG expression and immunoreactive scores (IRS) were calculated. CXCR4 exhibited significantly higher expression in AA tumors, with &gt; 85% of AA prostate tumors showing weak to strong CXCR4 expression, compared to &lt; 5% in CA specimens. While immunostaining for IL-6, FASN, MMP9 and p-Akt did not provide a significant distinction between CA and AA cases. IRS analysis confirmed higher expression of CXCR4 in AA cancers, compared to CA prostate cancer (p &lt; 0.001). MMP9 and IL6 expression were moderately higher in AA cancer compared to CA prostate cancer (p &lt; 0.05). In contrast, FASN expression was significantly higher in CA cancer, compared to AA prostate cancer (p &lt; 0.001). We further investigated the impact of these genes on biochemical recurrence-free survival (BCRFS) using Kaplan-Meier analysis to examine the differences between low-risk versus high-risk groups. BCRFS analysis demonstrated that CXCR4 is a determinant factor of recurrence risk in AA prostate cancer patients. The activation of the PI3K-Akt signaling pathway, particularly in AA patients, suggests its role in prostate cancer aggressiveness. Taken together, this study demonstrates the importance of differential expression of biomarkers which constitute the bulk tumors in driving cancer. The distinct gene expression patterns, especially the upregulation of CXCR4, in AA prostate cancer highlight its potential as a prognostic biomarker and a target for personalized treatment strategies. These findings encourage further study into the role of population-specific difference in adding CXCR4 in risk model construction, especially in machine learning models.
Citation Format: Amel A. Ahmed, Shiv Verma, Ibrahim M. Atawia, Daniel L. Shen, Gregory T. MacLennan, Pingfu Fu, Sanjay Gupta. Differentially expressed genes as prognostic markers in racial disparities of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7645.