Serum Starvation Sensitizes Anticancer Effect of Anemarrhena asphodeloides via p38/JNK-Induced Cell Cycle Arrest and Apoptosis in Colorectal Cancer Cells

The molecular mechanism underlying the anticancer effects of Anemarrhena asphodeloides (A. asphodeloides) on colon cancer is unknown. This is the first study evaluating the anticancer effect of A. asphodeloides extract (AA-Ex) in serum-starved colorectal cancer cells. Changes in cell proliferation and morphology in serum-starved MC38 and HCT116 colorectal cancer cells were investigated using MTS assay. Cell cycle and apoptosis were investigated using flow cytometry, and cell cycle regulator expression was determined using qRT-PCR. Apoptosis regulator protein levels and mitogen-activated protein kinase (MAPK) phosphorylation were assessed using western blotting. AA-Ex sensitively suppressed proliferation of serum-starved colorectal cancer cells, with MC38 and HCT116 cells showing greater changes in proliferation after treatment with AA-Ex under serum starvation than HaCaT and RAW 264.7 cells. AA-Ex inhibited cell cycle progression in serum-starved MC38 and HCT116 cells and increased the expression of cell cycle inhibitors (p53, p21, and p27). Furthermore, AA-Ex induced apoptosis in serum-starved MC38 and HCT116 cells. Consistently, AA-Ex suppressed the expression of the anti-apoptotic molecule Bcl-2 and upregulated pro-apoptotic molecules (cytochrome c, cleaved caspase-9, cleaved caspase-3, and cleaved-PARP) in serum-starved cells. AA-Ex treatment under serum starvation decreased AKT and ERK1/2 phosphorylation in the cell survival signaling pathway but increased p38 and JNK phosphorylation. Furthermore, AA-Ex treatment with serum starvation increased the levels of the transcription factors of the p38 and JNK pathway. Serum starvation sensitizes colorectal cancer cells to the anticancer effect of A. asphodeloidesvia p38/JNK-induced cell cycle arrest and apoptosis. Hence, AA-Ex possesses therapeutic potential for colon cancer treatment.