Sonic Hedgehog Pathway Is Essential for Maintenance of Cancer Stem-Like Cells in Human Gastric Cancer

Abstract

Abnormal activation of the Sonic hedgehog (SHH) pathway has been described in a wide variety of human cancers and in cancer stem cells (CSCs), however, the role of SHH pathway in gastric CSCs has not been reported. In this study, we investigated the possibility that abnormal activation of the SHH pathway maintained the characteristics of gastric CSCs. First, we identified cancer stem-like cells (CSLCs) from human gastric cancer cell lines (HGC-27, MGC-803 and MKN-45) using tumorsphere culture. Compared with adherent cells, the floating tumorsphere cells had more self-renewing capacity and chemoresistance. The cells expressing CSCs markers (CD44, CD24 and CD133) were also significantly more in tumorsphere cells than in adherent cells. More importantly, in vivo xenograft studies showed that tumors could be generated with 2×104 tumorsphere cells, which was 100-fold less than those required for tumors seeding by adherent cells. Next, RT-PCR and Western blot showed that the expression levels of Ptch and Gli1 (SHH pathway target genes) were significantly higher in tumorsphere cells than in adherent cells. The results of quantitative real-time PCR were similar to those of RT-PCR and Western blot. Further analysis revealed that SHH pathway blocked by cyclopamine or 5E1 caused a higher reduction in self-renewing capacity of HGC-27 tumorsphere cells than that of adherent cells. We also found that SHH pathway blocking strongly enhanced the efficacy of chemotherapeutic drugs in HGC-27 tumorsphere cells in vitro and in vivo but had no significant effect in adherent cells. Finally, we isolated the tumorspheres from gastric cancer specimen, these cells also had chemoresistance and tumorigenic capacity, and SHH pathway maintained the gastric CSLCs characteristics of tumorsphere cells from primary tumor samples. In conclusion, our data suggested that SHH pathway was essential for maintenance of CSLCs in human gastric cancer.

RETRACTED ARTICLE: Characterization of cancer stem-like cells in the side population cells of human gastric cancer cell line MKN-45

“…Some investigators use cell surface markers to get the CSCs, such as CD44 + /CD24 −/low /Lin − for breast cancer CSCs and CD44 + /CD24 + for gastric CSCs (Al-Hajj et al, 2003;Zhang et al, 2011). Some developed tumor sphere in serum-free medium to obtain CSCs (Song et al, 2011;Yin et al, 2011). We selected FACS to obtain the cancer stem-like cells.…”

Gastric tumor-initiating CD44+ cells and epithelial-mesenchymal transition are inhibited by γ-secretase inhibitor DAPT

“…Numerous studies have focused specifically on the signaling pathways that may mediate the resistance of CSCs (21,22). Notch signaling is involved in the development and progression of several solid tumors (23).…”

Inhibition of Gli1 results in altered c-Jun activation, inhibition of cisplatin-induced upregulation of ERCC1, XPD and XRCC1, and inhibition of platinum–DNA adduct repair

“…The Hedgehog pathway is of critical importance in early fetal development, 20,21 in maintenance of the cancer stem cell, 22,23 and of critical clinical importance in several important malignancies. 24 --26 Its role in cancer stem cell biology is not clear, but may be related in part to the extreme drug resistance phenotype of cancer stem cells.…”