Effect of Ursolic Acid on Proliferation and Apoptosis of Colorectal Cancer Cells Based on Akt/FoxO Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo investigate the effects and molecular mechanism of ursolic acid on the proliferation and apoptosis of colorectal cancer cells. MethodThe proliferation inhibition rate of human colorectal cancer RKO cells treated with different concentrations of ursolic acid （0， 5， 10， 15， 20， 25， 30 μmol·L-1） was detected by cell counting kit-8 （CCK-8）， and the half maximal inhibitory concentration （IC50） at 24 h and 48 h was calculated. According to the IC50 of RKO cells treated with ursolic acid for 24 h， two concentrations were selected for subsequent experiments. The colony formation assay was used to detect the proliferation ability of the cells and flow cytometry was used to detect the apoptosis rate and cell cycle arrest after treatment of RKO cells with ursolic acid. After treatment of RKO cells with ursolic acid for 24 hours， the expression of B-cell lymphoma 2 （Bcl-2）-associated X protein （Bax） in RKO cells， Bcl-2 in Raji cells， PMA responsive gene in T lymphocyte （Noxa）， cyclin-dependent kinase inhibitor 1A （p21）， cyclin-dependent kinase inhibitor 1B （p27）， cyclin-dependent kinase 4 （CDK4）， protein kinase B （Akt）， phosphorylated Akt （p-Akt）， forkhead transcription factor O3a （FoxO3a）， and phosphorylated FoxO3a （p-FoxO3a） was determined by Western blot. ResultCompared with the blank group， the ursolic acid groups could inhibit the viability of RKO cells （P<0.05， P<0.01）， and the colony formation rates of RKO cells in the ursolic acid groups were reduced （P<0.05， P<0.01） in a concentration-dependent manner. The cells in the ursolic acid group （20 μmol·L-1） experienced cell cycle arrest， which increased in the early stage of synthesis， ie， the G0/G1 phase （P<0.05） as compared with the results in the blank group. Compared with the blank group， the ursolic acid groups （15 and 20 μmol·L-1） showed increased protein expression of p21 and p27， decreased expression of CDK4 protein （P<0.05， P<0.01）， and increased apoptosis rate， and the ursolic acid group （20 μmol·L-1） showed increased protein expression of Bax and Noxa and decreased expression of Bcl-2 （P<0.05， P<0.01）. In terms of mechanism， compared with the blank group， the ursolic acid group （20 μmol·L-1） down-regulated the expression of p-Akt protein and up-regulated the expression of p-FoxO3a （P<0.05， P<0.01）， and there was no significant change in the total protein of Akt and FoxO3a. ConclusionUrsolic acid can effectively inhibit the proliferation of colorectal cancer RKO cells and promote cell apoptosis， which may be related to the Akt/FoxO pathway.