Enhanced anticancer effects of Scutellaria barbata D. Don in combination with traditional Chinese medicine components on non-small cell lung cancer cells

Experience-based herbal medicine as a complementary to modern western medicine has triggered an array of studies in quest of novel anticancer drugs. Scutellaria barbata D. Don (SB) is commonly used to treat different types of cancers, but its molecular mechanism of action is not clearly understood. In this study, we attempted to elucidate the mode of action of a traditional Chinese medicine prescription with a total of 14 components, named Lian-Jia-San-Jie-Fang (LJSJF, 莲甲散结方 in Chinese), where SB works as the “principle” against non-small cell lung cancer (NSCLC) cells. Four different NSCLC cell lines (A549, H460, H1650, and H1975) were used. Cytotoxicity, in vitro tumorigenicity, gene expression, and protein expression were analyzed by MTT assay, soft agar assay, real-time PCR, and Western blots, respectively. Among the 14 components in LJSJF, SB was the only one to possess cytotoxic effects at its pharmacologically relevant doses. Additionally, we observed synergistically dose-dependent cytotoxic effects of SB in combination with other LJSJF components. After SB or LJSJF treatment, significant reductions in colony number and/or size were observed in A549 and H460; a notable dose-dependent decrease in EGFR was observed in A549, H460, and H1650; significant downregulation in EGFR and its downstream signaling targets mTOR and p38MAPK were also observed in A549 and H460; and p53 and p21 were significantly increased while survivin, cyclin D1, and MDM2 were significantly decreased in A549. Additionally, p53, p21, and Mettl7b were decreased, but p73 was increased in H460. Neither EGFR nor p53 was changed in H1975. Therefore, SB or LJSJF may induce cytotoxic effects by regulating multiple and/or distinct apoptotic pathways in different NSCLC cells. LJSJF exerts more pronounced cytotoxic effects against NSCLC cells than SB does by synergistically regulating the underlining molecular mechanisms including EGFR and/or p53 signaling pathways.