Suppression of PI3K/AKT/mTOR signaling pathway by ethyl acetate extract from garden balsam seed induces apoptosis and inhibits migration in prostate cancer cells

Abstract

Objective

This research was intended to investigate the potential mechanism of garden balsam seed ethyl acetate (GBSEA) induces the apoptosis and migration of prostate cancer cells by inhibiting PI3K/AKT/mTOR signaling pathway, providing new theoretical evidence for the biological value of GBSEA extract and its preventive effects on prostate cancer (PC).

Methods

The main components of GBSEA extract were prepared and identified. Primary PC cells (PCCs) and LNCaP cells were treated with GBSEA extract at concentrations of 30, 60, 90, 120, 150, 180, and 210 μg/mL. The influence of GBSEA extract on proliferation, apoptosis, and migration of primary PCCs and LNCaP cells was analyzed using cell counting kit-8 (CCK8) and Transwell migration assays. The impact of GBSEA extract on levels PI3K/AKT/mTOR signaling pathway-associated proteins was assessed by Western blotting, and real-time fluorescent quantitative PCR (RT-qPCR) was employed to evaluate the influence of GBSEA extract on levels of apoptosis-related genes.

Results

GBSEA extract contained six compounds, including β-sitosterol, α-spinasterol, hexadecanoic acid, quercetin methyl ether, quercetin, and kaempferol. As the GBSEA extract concentration increased, the proliferation rate of primary PCCs and LNCaP cells sharply decreased in contrast to the control group (0 μg/mL), showing a concentration-dependent effect (P < 0.05). The IC50 values for inhibiting the proliferation of the primary PCCs and LNCaP cells were 67 μg/mL and 128 μg/mL. After treatment with GBSEA extract, the apoptosis rate of primary PCCs and LNCaP cells was substantially higher relative to that in control group without GBSEA extract (P < 0.05), while migration rate was lower (P < 0.05). The levels of PI3K, pAKT, and mTOR (in LNCaP cells) were considerably lower based on those in control group, and the Bcl-2 level (in primary PCCs and LNCaP cells) was sharply lower, all showing obvious significances (P < 0.05). However, the Bax, Caspase-3, and Caspase-9 levels (in primary PCCs and LNCaP cells) were remarkably higher relative to those in control group, with obvious significances observed (P < 0.05).

Conclusions

GBSEA extract can inhibit apoptosis and migration of prostate cancer cells induced by PI3K/AKT/mTOR signaling pathway, which provides a new theoretical basis for the prevention of prostate cancer.