Biological Activity and Cell Cycle Effects of Natural Extract Kaempferol on Androgen-dependent Prostate Cancer Cells

Background: There is an abnormal enhancement of androgen receptor activity in prostate cancer cells, leading to increased sensitivity to androgens and the promotion of cancer cell proliferation. Purpose: This study aimed to investigate the effects of Eucommia ulmoides leaf-derived kaempferol extract on the biological activity and cell cycle of androgen-dependent prostate cancer cells (LNCaP) through in vitro cell culture experiments. Methods: Kaempferol was isolated and extracted from the hydrolysate of E. ulmoides leaves, and its clearance rates for superoxide anion (O2-) and hydroxyl radical (<middle dot>OH) were analyzed. Subsequently, LNCaP cells were treated with kaempferol at concentrations of 0.0, 0.5, 1.0, and 2.0 mu mol L--(1) and grouped accordingly. Changes in cell proliferation inhibition rate, apoptosis rate, cell cycle distribution, and levels of apoptosis-related proteins were assessed. Results: The recovery rate of kaempferol from E. ulmoides leaves was approximately 98.23%, with kaempferol contents of 0.008% before hydrolysis and 0.089% after hydrolysis. As the concentration of kaempferol increased, the clearing rate (CR) of O2- and <middle dot>OH free radicals also gradually increased (p < .05). In contrast to the 0.0 <mu>mol L--(1) group, the 0.5, 1.0, and 2.0 mu mol L--(1) groups have exhibited greatly enhanced proliferation inhibition rate and apoptosis rate of LNCaP, a remarkable decrease in the S-phase proportion, a substantial increase in the G2/M-phase proportion, and a significant reduction in Bcl-2 protein. Conversely, expressions of Bax, caspase-3, and caspase-9 were significantly upregulated (p < .05). Conclusion: E. ulmoides leaf-derived kaempferol extract demonstrated a pronounced anti-oxidant effect. Kaempferol was found to inhibit LNCaP proliferation and promote its apoptosis by modulating the cell cycle and the apoptosis-related proteins.