Abstract
Iridoids are a special class of cyclopentanoid monoterpenes, which exhibit a wide range of biological effects. The present study aimed to investigate the potential effects of three iridoids genipin, geniposide and geniposidic acid on three human oral squamous cell carcinoma (OSCC) cell lines HSC-2, SCC-9 and A253 in addition to studying the possible underlying mechanisms. Cell viability assay revealed that geniposide treatment significantly suppressed the proliferation of all three cancer cell lines. In addition, geniposide induced SCC-9 cell cycle arrest at the G2/M phase (flow cytometry) through downregulation of cyclin-dependent kinase 2 and Cyclin A2 expression (western blot analysis), whilst also inducing cell apoptosis (flow cytometry and acridine orange/ethidium bromide staining) by dissipating the mitochondrial membrane potential (flow cytometry), and upregulating the expression of cleaved caspase-3 and cleaved poly-ADP ribose polymerase (western blot analysis). A wound-healing assay indicated that geniposide impaired SCC-9 cell migration by increasing the expression of E-cadherin (western blot analysis), whilst suppressing the expression of MMP-2 (western blot analysis). Western blot analysis also demonstrated that geniposide induced autophagy in SCC-9 cells by upregulating the expression of Beclin-1 and light chain 3-II. Mechanistically, geniposide activated the 5'-AMP-activated protein kinase signaling pathway and inhibited the JNK signaling pathway in SCC-9 cells (western blot analysis). The present results indicated that geniposide is able to inhibit the proliferation and migration of the tongue squamous carcinoma cell line SCC-9, suggesting a potential strategy for OSCC treatment.