Hedgehog signaling pathway is inactive in colorectal cancer cell lines

Abstract

The Hedgehog (Hh) signaling pathway plays an important role in human development. Abnormal activation of this pathway has been observed in several types of human cancers, such as the upper gastro-intestinal tract cancers. However, activation of the Hh pathway in colorectal cancers is controversial. We analyzed the expression of the main key members of the Hh pathway in 7 colon cancer cell lines in order to discover whether the pathway is constitutively active in these cells. We estimated the expression of SHH, IHH, PTCH, SMO, GLI1, GLI2, GLI3, SUFU and HHIP genes by RT-PCR. Moreover, Hh ligand, Gli3 and Sufu protein levels were quantified by western blotting. None of the cell lines expressed the complete set of Hh pathway members. The ligands were absent from Colo320 and HCT116 cells, Smo from Colo205, HT29 and WiDr. GLI1 gene was not expressed in SW480 cells nor were GLI2/GLI3 in Colo205 or Caco-2 cells. Furthermore the repressive form of Gli3, characteristic of an inactive pathway, was detected in SW480 and Colo320 cells. Finally treatment of colon cancer cells with cyclopamine, a specific inhibitor of the Hh pathway, did not downregulate PTCH and GLI1 genes expression in the colorectal cells, whereas it did so in PANC1 control cells. Taken together, these results indicate that the aberrant activation of the Hh signaling pathway is not common in colorectal cancer cell lines. ' 2007 Wiley-Liss, Inc.

Gene Signatures Associated with Mouse Postnatal Hindbrain Neural Stem Cells and Medulloblastoma Cancer Stem Cells Identify Novel Molecular Mediators and Predict Human Medulloblastoma Molecular Classification

“…In agreement with previous observations in medulloblastoma cell cultures and serum-cultured colon cancer cells (25,26), the expression of downstream mediators of Shh pathway in NSCs and medulloblastoma CSCs was modest, and, accordingly, Shh pathway activation was marginally relevant for proliferation and self-renewal of NSC/CSCs (27) as well as in CSCs isolated from the same Ptch mouse model (28) or other brain tumors (29). Indeed, both NSC/CSC-derived neurospheres employed in those studies were maintained in vitro for very few subculturing passages.…”

Expression and Clinical Significance of Hedgehog Signaling Pathway Related Components in Colorectal Cancer

“…As PTCH and GLI1 were indicators of Hh pathway activity, He concluded that the Hh pathway was not active in these CRC cell lines (Yoshikawa et al, 2009). Chatel analyzed the gene and protein expressions DOI:http://dx.doi.org/10.7314/APJCP.2012.13.5.2319 of the main key members of the Hh pathway (SHH, IHH, PTCH, SMO, GLI1, GLI2, GLI3, SUFU and HHIP) in 7 colon cancer cell lines and found none of them expressed the complete set of Hh pathway members (Chatel et al, 2007). However, by analyzing CRC cell lines as well as human tissues from 40 patients with local or metastatic CRCs, Varnat found consistent expression of PTCH, GLI1 and SHH as well as other Hh-GLI1 pathway components.…”

“…The data about the roles they play on CRC have not been well documented. Some of them even remained controversial (Berman et al, 2003;Douard et al, 2006;Monzo et al, 2006;Chatel et al, 2007;Varnat et al, 2009; 2320 Yoshikawa et al, 2009;Fu et al, 2010;Saqui-Salces and Merchant, 2010;You et al, 2010;Tapati et al, 2011). There were disagreements in the roles of downstream Hh signaling components i.e.…”

Downregulation of the hedgehog receptor PTCH1 in colorectal serrated adenocarcinomas is not caused by PTCH1 mutations

“…Paracrine signaling was further verified in xenografts with human cell lines and cancer biopsies in mice [18]. According to Chatel and co-workers, activation of Hh pathway is not a common event in cultured cells [19]. However, several other studies have addressed the essential role of epithelial Hh signaling in CRC development, growth, stem cell renewal, and metastatic behavior in advanced cancer [20][21][22][23][24].…”