Suppression of Cellular Proliferation in PC3 Prostate Cancer Cells by Green Tea Extract Through Induction of miR-34a Expression

Abstract

Prostate cancer (PC) ranks as the fifth major cause of cancer-related fatalities globally. Exploring new methods with high efficacy and low side effects by using new compounds is always desired. Tea is considered the second most commonly consumed beverage among the population of the world. Polyphenols (or catechins) in green tea play a significant role in cellular signaling pathways. Herein, we evaluate the effects of green tea extract on suppression of cellular proliferation through testing the expression of miR-34a in PC3 prostate cancer cells. In this respect, PC3 prostate cancer cells were cultured and treated with green tea extract for 48 h. By using the qRT-PCR method, the expression of miR-34a was analyzed. Moreover, the expression of key proteins to regulate cellular proliferation, such as prostate specific antigen (PSA), AKT, cyclin dependent kinase 1 (CDK1), cyclin B1, c-Myc, p53, and phospho-androgen receptor (p-AR) was evaluated by using western blot. Our results indicated the induction of miR-34a, p53, and the inhibition of cyclin B1, p-AR, CDK1, p-AKT, PSA, c-Myc, and p-CDK1. Our findings can be used to design anti-tumor regimens that utilize natural product ingredients. However, additional research will be needed to identify anticancer activities of green tea via miR-34a in prostate cancer cells.

Keywords: MiR‐34a; PC3 prostate cancer cells; cell proliferation; green tea extract.

FIGURE 1

Up‐regulation of miR‐34a in PC3 cancer cells by green tea extract. PC3 cancer cell viability was shown by using MTT assay in different concentration to find IC₅₀ (A); Morphological changes of PC3 cancer cells before and after treatment with green tea extract. The experiments were performed three times original microscope magnification, ×20, scale bar, 10 μm; Images were taken using a phase contrast inverted microscope (INV100, BEL Engineering, Italy). The arrows indicate cell shrinkage (B); Relative expression of miR‐34a was analyzed (C). Data represent mean ± SD of three independent experiments. *p < 0.05 was considered to be statistically significant.

FIGURE 2

The expression of indicated proteins (cyclin B1, p‐CDK1, CDK1, AKT, and p‐AKT) versus Actin (an internal control) was shown in PC3 cells using western blot (A). (TCL: Total cell lysate). Data represent mean ± SD. *p < 0.05 was considered to be statistically significant. NS, not significant. The cellular death induction in PC3 cancer cells using DAPI staining. The experiments were performed three times (original microscope magnification, 40×, Scale bar, 10 μm; By using an inverted fluorescent microscope (Nikon Eclipse Ti‐E), all images were taken). The arrows indicate nuclear condensation of apoptotic cells (B). PC3 cancer cell viability was shown by using MTT assay (C).

FIGURE 3

The expression of indicated proteins (AR, p‐AR, p53, c‐Myc, and PSA) versus Actin (an internal control) was shown in PC3 cells after treatment with green tea extract using western blot. (TCL: Total cell lysate) (A, B). Data represent mean ± SD. *p < 0.05 was considered to be statistically significant. NS, not significant.

FIGURE 4

Schematic model of spheroids formation by using hanging drop technique (A). Relative expression of miR‐34a was analyzed. Data represent mean ± SD of three independent experiments. *p < 0.05 was considered to be statistically significant (B). The expression of cyclin B1 protein versus Actin (an internal control) was shown in PC3 cells using western blot. (TCL: Total cell lysate) (C). Data represent mean ± SD. *p < 0.05 was considered to be statistically significant.