Betulinic acid isolated from induces apoptosis and reduces the mTOR/PI3K/AKT signaling pathway in endometrial cancer cells.

Abstract

Endometrial cancer is one of the most common gynecological cancers worldwide, and an average of 42,000 women die each year. Chemotherapy, radiotherapy, and surgery are among the treatments available for endometrial cancer. Currently, drugs used for chemotherapy have had limited success in increasing the cure rate. Betulinic acid, a lupane-type triterpene widely found in the plant kingdom, has attracted attention for cancer treatment in recent years due to its ability to inhibit tumor growth and induce cell apoptosis. The aim of this study is to investigate the mTOR pathway-mediated anticancer effects of betulinic acid in human endometrial cancer cells. The effect of betulinic acid on Ishikawa cell viability was determined by the CCK-8 method. Its effect on the expression of genes involved in apoptosis and the mTOR pathway was assessed by real-time PCR. The effect on protein expression in the mTOR pathway was evaluated with immunohistochemistry and western blot, and the effects on apoptosis via Annexin V. Betulinic acid reduced Ishikawa endometrial cancer cell proliferation. Betulinic acid administration caused a significant decrease in Bcl2 (=0.008) expression and increased caspase-8 (=0.001) expression in Ishikawa cells. The results of Annexin V supported the idea that betulinic acid administration triggered apoptosis in Ishikawa cells. The mean rate of apoptotic cells in the betulinic acid group was 22±3.23%, while it was 2.31±0.2% in the control group (=0.02). Betulinic acid caused a significant decrease in the expression of AKT1 (=0.0001) and a significant increase in the expression of RAPTOR (=0.00002). Betulinic acid administration also significantly decreased protein expression in the mTOR pathway. The percentage of p-PI3K, p-AKT, and p-mTOR-positive cells in Ishikawa cells was 89.39±5.19%, 74.84%±5.07, and 82.02%±6.14, respectively, in the control group. In the betulinic acid group, these values were 49.12±19.12% (=0.002), 44.46±7.39% (<0.001), and 53.70±8.94% (<0.001), respectively. This study showed that betulinic acid decreased Ishikawa cell proliferation, triggered apoptosis, and decreased mTOR signaling; thus, betulinic acid may be a potential anticancer agent for the treatment of endometrial cancer.