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. Objectives 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. Materials and Methods Kaempferol was isolated and extracted from the hydrolysate of E. ulmoides leaves, and its clearance rates for superoxide anion (O 2 − ) and hydroxyl radical (·OH) were analyzed. Subsequently, LNCaP cells were treated with kaempferol at concentrations of 0.0, 0.5, 1.0, and 2.0 µmol 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 O 2 − and ·OH free radicals also gradually increased ( p < .05). In contrast to the 0.0 µmol L⁻¹ group, the 0.5, 1.0, and 2.0 µmol 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 antioxidant effect. Kaempferol was found to inhibit LNCaP proliferation and promote its apoptosis by modulating the cell cycle and the apoptosis-related proteins.