Matrine inhibits the proliferation, invasion and migration of castration-resistant prostate cancer cells through regulation of the NF-κB signaling pathway

Abstract

Matrine is a naturally occurring alkaloid extracted from the Chinese herb Sophora flavescens. It has been demonstrated to exhibit antiproliferative properties, promote apoptosis and inhibit cell invasion in a number of cancer cell lines. It has also been shown to improve the efficacy of chemotherapy when it is combined with other chemotherapy drugs. However, the therapeutic efficacy of matrine for prostate cancer remains poorly understood. In the present study, we showed that matrine inhibited the proliferation, migration and invasion of both DU145 and PC-3 cells in a dose- and time-dependent manner. It also reduced the cell population at S phase and increased the cell population at sub-G1 phase. The increases in both the apoptotic cell population and cell population at S and sub-G1 phases consistently indicated a pro-apoptotic effect of matrine. Decreases in levels of P65, p-P65, IKKα/β, p-IKKα/β, IKBα and p-IKBα as detected by immunoblot analysis in the matrine-treated DU145 and PC-3 cells suggested an involvement of the NF-κB signaling pathway. Therefore, it is a novel promising addition to the current arsenal of chemotherapy drugs for the treatment of androgen-independent prostate cancer.

Figure 1

Matrine reduces the proliferation of prostate cancer cells. (A and B) Plots of the proliferation rates of prostate DU145 (A) and PC-3 cells (B) incubated with increasing concentrations of matrine for increasing time periods. Values of OD490 represent the number of viable cells. Data here or throughout are the average ± standard deviation of at least three repeats. Statistical significance was determined by the Student's t-test. ^*P≤0.05. (C and D) Plots of the rates of growth inhibition for increasing concentrations of matrine for increasing time periods in DU145 (C) or PC-3 cells (D). (E and F) Plots of rates of growth inhibition for increasing concentrations of matrine in DU145 (E) or PC-3 cells (F).

Figure 2

Matrine impairs the migration and invasion of prostate cancer cells. (A–D) Representative images (A and B) and plots of the number (C and D) of invaded DU145 (A and C) and PC-3 cells (B and D) per 10,000 seeded cells. (E–H) Representative images (E and F) and plots of the number (G and H) of migrated DU145 (E and G) and PC-3 cells (F and H) per 10,000 seeded cells in the presence of increasing concentrations of matrine for 48 h.

Figure 3

Matrine delays the progress of the cell cycle of prostate cancer cells. (A and B) Representative histograms showing the results from flow cytometric analyses of the DNA content of DU145 (A) and PC-3 cells (B) in the presence of different concentrations of matrine. (C and D) Plots of the percentages of DU145 (C) and PC-3 cells (D) at the sub-G1, G1, S and G2 phases in the presence of increasing concentrations of matrine. The inserted numbers are the percentage of cells at the corresponding phase.

Figure 4

Matrine promotes the apoptosis of prostate cancer cells. (A and B) Representative dot plots of apoptotic cells detected in the DU145 (A) and PC-3 cells (B) treated with increasing concentrations of matrine by flow cytometry. (C–H) Plots of the percentages of early (C and D), late (E and F) and total apoptotic cells (G and H) in the DU145 (C, E and G) and PC-3 cells (D, F and H) treated with increasing concentrations of matrine.

Figure 5

Matrine suppresses the NF-κB signaling pathway in prostate cancer cells. (A and B) Representative immune-blot results showing the intensities of P65, p-P65, IKKα/β, p-IKKα/β, IKBα and p-IKBα in DU145 (A) or PC-3 cells (B) treated with matrine at the concentrations as indicated. (C and D) Plots of the relative intensities of proteins shown in panel A and B as representatives against increasing concentrations of matrine in DU145 (C) and PC-3 cells (D). Levels of proteins are the ratios to GAPDH levels.