Abstract 5249: Polyphenon E effects MXD1 and RGS4 gene expression in PC-3 prostate cancer cells
Authors: Carastro L. Michael , Vallebuona Ethan J. , Cordova Ricardo , Gannon Ashley N. , Costello Corrine M. , Declet-Bauzo Ricardo A. , Kim Seung Joon , Kumar Nagi , Park Jong Y. 
Published: April 2023

Polyphenon E (Poly E) is a standardized, caffeine-free green tea extract with defined polyphenol content. Oral Poly E administration confers chemoprotective activity against prostate cancer (PCa) progression in the TRAMP model of human PCa. Poly E has limited activity against human PCa, but only in those previously diagnosed with atypical small acinar proliferation or high-grade prostate intraepithelial neoplasia. The molecular mechanisms underpinning Poly E chemopreventive activities against PCa are not fully understood. We hypothesized Poly E treatment of PCa cells induces gene expression changes, which could involve molecular mechanisms underpinning the limited Poly E chemoprevention activity against PCa. PC-3 cells were cultured in complete growth media supplemented with varied Poly E concentrations (0, 100, 200, or 300 mg/L) for 24 hr. RNA was isolated for comparative DNA microarray (0 vs. 200 mg/L Poly E) and subsequent qRT-PCR analyses for validation. Microarray data for 54,613 genes were filtered for &gt; 2-fold expression level changes, with 8,319 increased and 6,176 genes decreased. Seven genes (CASP8, CBLB, CCNB1, HDAC4, MXD1, RGCC, RGS4) involved in key cellular signaling pathways and with &gt; 2-fold expression level changes, as well as a control gene (RB1), were selected for qRT-PCR analyses. These eight genes are listed with corresponding fold-change gene expression values for each microarray probe set (Table 1). The qRT-PCR analyses identified two genes with significantly increased expression, MXD1 (13.98-fold; p=0.0003) and RGS4 (21.98-fold; p=0.0011), between poly E treatment levels. The significantly increased MXD1 and RGS4 gene expression in Poly E-treated PC-3 cells, and the Poly E-dose dependence of MXD1 gene expression increases, could implicate MXD1 and RGS4 in the PCa chemopreventive activity of Poly E. Future experimental directions include cell cycle profile and Annexin V analyses, immunoblotting analyses, and including other established PCa cell lines in these studies.

Microarray Data from Poly E-treated PC-3 Cells Affymetrix Probe ID Gene symbol Log2-Fold Change 213373_s_at CASP8 -2.23 1553306_at CASP8 -3.20 208348_s_at CBLB 19.01 209682_at CBLB 3.83 214710_s_at CCNB1 -2.77 228729_at CCNB1 -3.47 1554322_a_at HDAC4 -2.47 204225_at HDAC4 -3.23 228813_at HDAC4 -4.45 206877_at MXD1 13.56 228846_at MXD1 7.35 226275_at MXD1 1.91 211540_s_at RB1 1.85 203132_at RB1 -1.43 218723_s_at RGCC 23.12 239827_at RGCC 1.22 204338_s_at RGS4 20.54 204337_at RGS4 6.12 204339_s_at RGS4 3.69

Citation Format: L. Michael Carastro, Ethan J. Vallebuona, Ricardo Cordova, Ashley N. Gannon, Corrine M. Costello, Ricardo A. Declet-Bauzo, Seung Joon Kim, Nagi Kumar, Jong Y. Park. Polyphenon E effects MXD1 and RGS4 gene expression in PC-3 prostate cancer cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5249.