Abstract
Abstract The G-protein coupled calcium sensing receptor (CaSR) is a robust promoter of differentiation in colonic epithelial cells. Loss of CaSR expression allows cancer cells to escape from CaSR control. Loss of CaSR expression augments the malignant phenotype in vitro and is associated with undifferentiated and invasive colon carcinomas in vivo (Cancer Res. 63: 67, 2003; 65: 493, 2005; Int. J. Cancer 121: 1455, 2007;126: 631, 2010; Mol. Carcinogenesis 48: 202, 2009). Interestingly, human colon carcinoma cell lines contain small subpopulations (10-20%) that do not express CaSR (termed CaSR null cells). Here, we report the isolation and characterization of CaSR null cells from the CBS and HCT116 human colon carcinoma cell lines. We isolated CaSR null cells by magnetic cell sorting using monoclonal anti-CaSR antibody. CaSR null cells were cultured and maintained in stem cell culture medium. Biologic characterization of CaSR null cells showed that these cells were non-adherent and grew as three-dimensional spherical clusters with an increase in propensity for anchorage independent growth. CaSR null cells were highly invasive in matrigel invasion assays and resistant to treatment with cytotoxic drugs. Western analysis showed that CaSR null cells expressed a high level of thymidylate synthase and survivin which have been reported to be an underlying basis of drug resistance in colon cancer. Western analysis also showed that CaSR null cells expressed a high level of the previously reported cancer stem cell markers CD133, CD44 and Nanog. Molecular profiling by quantitative RT-PCR revealed a significant increase in the expression of epithelial-mesenchymal transition associated mRNAs in CaSR null cells. These mRNAs were N-cadherin, β-catenin, vimentin, fibronectin, FSP1, Snail1, Snail2, Twist, FOXC2 and SIP1. Interestingly, CaSR null cells re-expressed CaSR, over time, when placed in culture medium used to propagate the parental CBS and HCT116 cells. Re-expression of CaSR in CaSR null cells attenuated the expression of markers associated with the malignant phenotype. We conclude that CaSR null cells represent a highly malignant subpopulation of colon cancer cells and that these cells may possess cancer stem cell-like properties. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5212. doi:10.1158/1538-7445.AM2011-5212
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call