Extracts of Opuntia humifusa Fruits Inhibit the Growth of AGS Human Gastric Adenocarcinoma Cells

Opuntia humifusa (OHF) has been used as a nutraceutical source for the prevention of chronic diseases. In the present study, the inhibitory effects of ethyl acetate extracts of OHF on the proliferation of AGS human gastric cancer cells and the mode of action were investigated. To elucidate the antiproliferative mechanisms of OHF in cancer cells, the expression of genes related to apoptosis and cell cycle arrest were determined with real-time PCR and western blot. The cytotoxic effect of OHF on AGS cells was observed in a dose-dependent manner. Exposure to OHF (100 μg/mL) significantly induced (P<0.05) the G1 phase cell cycle arrest. Additionally, the apoptotic cell population was greater (P<0.05) in OHF (200 μg/mL) treated AGS cells when compared to the control. The expression of genes associated with cell cycle progression (Cdk4, Cdk2, and cyclin E) was significantly downregulated (P<0.05) by the OHF treatment. Moreover, the expression of Bax and caspase-3 in OHF treated cells was higher (P<0.05) than in the control. These findings suggest that OHF induces the G1 phase cell cycle arrest and activation of mitochondria-mediated apoptosis pathway in AGS human gastric cancer cells.

Anticancer properties of extracts from Opuntia humifusa against human cervical carcinoma cells

In this study, we found that the total polyphenol and ascorbic acid levels in the fruit of Opuntia humifusa are higher than those in other parts of the plant. We further hypothesized that antioxidants in O. humifusa might affect the growth or survival of cancer cells. Hexane extracts of seeds and ethyl acetate extracts of fruits and stems significantly suppressed the proliferation of HeLa cervical carcinoma cells, but did not affect the proliferation of normal human BJ fibroblasts. Additionally, the extracts of O. humifusa induced G1 phase arrest in HeLa cells. The O. humifusa extracts reduced the levels of G1 phase-associated cyclin D1, cyclin-dependent kinase 4 (Cdk4), and phosphorylated retinoblastoma proteins. Moreover, p21(WAF1/Cip1) and p53 expression significantly increased after treatment. We examined the effects of ethyl acetate extracts of O. humifusa fruit (OHF) on HeLa cells xenograft tumor growth. OHF treatment significantly reduced tumor volume and this decrease was correlated with decreased Cdk4 and cyclin D1 expression. Furthermore, flavonoids, trans Taxifolin, and dihydrokaempferol, were isolated from OHF. Thus, this extract may be a promising candidate for treating human cervical carcinoma.

Opuntia humifusa partitioned extracts inhibit the growth of U87MG human glioblastoma cells

Opuntia humifusa, a member of the Cactaceae family widely distributed in the southern regions of the Korean peninsula, has potential bioactive functions and medicinal benefits. In the present study, we investigated the effect of hexane, ethyl acetate extracts and water partitioned fraction of O. humifusa on proliferation, G1 arrest and apoptosis in U87MG human glioblastoma cells. Glioblastoma cellular proliferation was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and the effects of O. humifusa partitioned extracts on cell cycle and apoptosis were analyzed by flow cytometry. Our results revealed that when U87MG cells were treated with hexane extracts and water partitioned fraction of O. humifusa, the number of viable cells decreased in a concentration-dependent manner. In addition, water partitioned fractions of O. humifusa induced G1 arrest and non-apoptotic cell death as well as significant increases in ROS production in U87MG cells. In conclusion, water partitioned fractions of O. humifusa induce G1 arrest and inhibit U87MG human glioblastoma cell proliferation.