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Prostate carcinoma is one of the most commonly diagnosed types of cancer and the second most common cause of cancer mortality among men in the USA and in Europe. Prostate specific antigen has emerged as a useful tumor marker in oncology. However, a relative lack of both specificity and sensitivity is leading to both over diagnosis and cases not being detected early enough. Therefore, we aimed to define and explore new therapeutic approaches and novel biomarkers for diagnosis and treatment of prostate cancer.
The Chinese medicinal herb Panax quinquefolius has been tested for its tumor selectivity and cytotoxic efficacy. P. quinquefolius saponins (PQS) have been shown to have anti-tumor effects in vivo and in vitro. In this study human prostate cancer cells DU145 and immortalized normal prostate epithelial cells PNT2 were treated with PQS. Cell viability assays, flow cytometric analysis of the cell cycle and FACS based apoptosis assays were performed after treatment. Western blot and quantitative real-time PCR analyses were performed to demonstrate the expression level of multiple cancer-related genes such as p53, p21, STAT3 and bcl2 as well as TMEM79. Microarray-based gene expression analysis was used to identify prostate specific gene expression patterns and to explore novel biomarkers for potential clinical use in prostate cancer diagnostics.
The inhibitory effects on the proliferation of DU145 showed that PQS inhibited the viability of human prostate cancer cells. Cell cycle arrest assay showed that PQS induced cell cycle arrest at the G0/G1 phase. PQS treatment up-regulated the expression of p53 and p21, down-regulated the expression of TMEM79, STAT3 and bcl2. The transmembrane protein TMEM79 was found to be highly enriched in normal prostate cells but was expressed only at low levels in prostate cancer cells.
Our results indicated that TMEM79 could be a novel biomarker candidate for prostate cancer diagnosis. PQS might be an effective herbal remedy playing a complementary or alternative role for treating prostate cancer in the future.
