Polyphenon E Alters Protein Levels in PC-3 Cells

Prostate cancer (PCa) is the most commonly diagnosed cancer in American men. Polyphenon E (Poly E) is a caffeine‐free standardized green tea extract reported to have chemopreventative activity. However, the mechanisms through which Poly E exhibits chemopreventative activity have not yet been fully elucidated. Our working hypothesis was that Poly E alters expression of specific genes to inhibit PCa cell proliferation. We previously conducted DNA microarray and qRT‐PCR analyses of RNA samples isolated from PCa cells (PC‐3) treated with varying levels of Poly E. The qRT‐PCR analysis assessed CASP‐8 and ATR expression changed not more than 2‐fold under Poly E treatments. The aim of the current study was to determine protein levels by Western blotting. PC‐3 cells were treated with Poly E (0 mg/L, 100mg/L, 200mg/L, and 300mg/L) for 24 hours. Protein was extracted and Western blot analysis was performed for ATR and CASP‐8 proteins. Results from Western Blot analysis for ATR indicated increased protein expression (1.43‐fold) at the 200mg/L Poly‐E treatment level compared to the untreated control, but were essentially unchanged at the 100mg/L and 300mg/L Poly E treatments (0.99‐fold and 0.91‐fold, respectively). These data were consistent with observed qRT‐PCR data. Western blot analysis for CASP‐8 indicated decreased protein expression levels of 0.36‐fold, 0.40‐fold and 0.38‐fold at the 100, 200, and 300 mg/L Poly E treatment levels, respectively. This result exhibited a trend similar to our CASP‐8 qRT‐PCR, but exhibited greater degree of decreases. Support or Funding Information This work was supported by a University of Tampa David Delo Research Professor Grant (to L.M.C). This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .