The objective of this study was to investigate the inhibitory effect of scutellarin on the differentiation of colonic cancer stem cells in vitro and in vivo and to explore its underlying hedgehog signaling-based mechanism. The effect of scutellarin on the growth in vitro of HT-29 cells-derived cancer stem-like cells(HT-29 CSC) was observed with 3 D cell culture. The effect of scutellarin on the transformation of HT-29 CSC cells was assessed by soft agar colony formation assay. Fetal calf serum was used to induce differentiation of stem cells and observe the effect of scutellarin on HT-29 CSC cells differentiation in vitro. The effects of scutellarin on mRNA expressions of Lgr5, c-Myc, CK20 and Nanog in HT-29 CSC cells were determined by quantitative Real-time polymerase chain reaction(qRT-PCR). The effects of scutellarin on protein expressions of c-Myc, Gli1 and Lgr5 in HT-29 CSC cells were examined by Western blot. After subcutaneous implantation of HT-29 CSC cells in nude mice, the effect of scutellarin on the mouse body weight and the growth of HT-29 CSC-derived tumor were explored. qRT-PCR was used for evaluating the effect of scutellarin on mRNA levels of CD133, Lgr5, Gli1, Ptch1, c-Myc, Ki-67, CK20 and Nanog in tumor. Western blot and immunohistochemistry analysis were used to detect the effect of scutellarin on protein expressions of c-Myc, Gli1, Lgr5, CD133 and Ki-67 in tumor. The in vitro experiments showed that scutellarin inhibited the growth, transformation and differentiation of HT-29 CSC cells, significantly down-regulated the mRNA levels of Lgr5, c-Myc, CK20 and Nanog in HT-29 CSC cells as well as the protein expression levels of c-Myc, Gli1 and Lgr5 in HT-29 CSC cells. Additionally, animal experiments showed that scutellarin significantly inhibited the growth of subcutaneous xenografts in nude mice, and down-regulated the mRNA expressions of CD133, Lgr5, Gli1, Ptch1, c-Myc, Ki-67, CK20 and Nanog as well as the protein levels of c-Myc, Gli1, Lgr5, CD133 and Ki-67 of xenografts in nude mice. Taken together, scutellarin could inhibit the differentiation of colo-nic cancer stem cells in vitro and in vivo, potentially by down regulation of hedgehog signaling pathway activity.
Keywords: cancer stem cell; colon cancer; differentiation; hedgehog signaling pathway; scutellarin.