RETRACTION: Apoptotic Effects of Rotundic Acid upon Human Esophagus and Lung Cancer Cells (Retraction of Vol 18, art no 1534735416635275, 2019)

Rotundic acid (RA) is a pentacyclic triterpenic acid. Apoptotic effects of RA at 4, 8, or 16 mu M in OE33 and A549 cell lines, an esophageal squamous cancer cell line and a non-small-cell lung cancer cell line, were examined. RA at 4 to 16 mu M inhibited the survival of both cell lines. RA at 8 and 16 mu M decreased Bcl-2 expression and at 4 to 16 mu M upregulated Bax and cleaved caspase-3 expression. RA treatments decreased the ratio of Bcl-2/Bax in those cells. RA at 4 to 16 mu M lowered Na+-K+-ATPase activity and reduced mitochondrial membrane potential in OE33 and A549 cells. RA at 8 and 16 mu M enhanced DNA fragmentation and caspase-3 and caspase-9 expression in OE33 cells. In A549 cells, RA increased caspase-3 expression in a concentration-dependent manner; but only at 8 and 16 mu M, it upregulated caspase-9 expression. RA treatments at 4 to 16 mu M decreased protein kinase c activity, suppressed the expression of cytochrome c and apoptosisinducing factor, and lowered the production of reactive oxygen species, vascular endothelial growth factor, transforming growth factor-beta 1, and tumor necrosis factor-a in both cell lines. RA at 8 and 16 mu M downregulated hypoxia-inducible factor1a expression. These findings suggest that RA could penetrate into OE33 and A549 cells and execute cytotoxic activities.