Genetic and epigenetic inactivation of T‐cadherin in human hepatocellular carcinoma cells

Abstract

T-cadherin is an atypical cadherin and growing evidence has indicated that T-cadherin exerts tumor-suppressive effects on cancers of epithelial cell type and also causes positive effects on tumor angiogenesis. Human hepatocellular carcinoma (HCC) is a hypervascular tumor and T-cadherin has been shown to be overexpressed in intratumoral endothelial cells of HCCs. However, the expression status and functions of T-cadherin in hepatocytes or HCC cells remain unclear. Here, we demonstrated that T-cadherin was underexpressed in HCC cells (26.5%, 13/49 cases), but was frequently (77.6%, 38/49) overexpressed in intratumoral endothelial cells immunohistochemically. Semiquantitative RT-PCR analysis also showed that the T-cadherin gene was underexpressed in 7 of 11 HCC cell lines. Loss of heterozygosity analysis revealed that 32-38% of the 42 human HCC samples had allelic losses at this locus. Upon pharmacological treatment with demethylating agent 5-aza-2 0 -deoxycytidine or histone deacetylase inhibitor trichostatin A, T-cadherin promoter hypermethylation and/or histone deacetylation was frequently observed in HCC samples and cell lines. Functionally, enforced expression of T-cadherin induced G 2 /M cell cycle arrest, reduced cell proliferation in low serum medium, suppressed anchorage-independent growth in soft agar and increased sensitivity to TNFa-mediated apoptosis in HCC cells. Intriguingly, we found that T-cadherin significantly suppressed the activity of c-Jun, a crucial oncoprotein constitutively activated in HCC cells. To conclude, T-cadherin was differentially expressed in human HCCs. The underexpression of T-cadherin in HCC cells suggests it may be another critical event in addition to T-cadherin-mediated angiogenesis during HCC development.

Malignant Transformation in Skin is Associated with the Loss of T-Cadherin Expression in Human Keratinocytes and Heterogeneity in T-Cadherin Expression in Tumor Vasculature

“…While in some studies the authors investigated the correlation between the hypermetylation of T-cadherin promoter or allelic loss, the others addressed the effect of T-cadherin reexpression on the malignant properties of cancer cells upon injection of cells in vivo in mouse models. Melanoma cells (Kuphal et al, 2009), hepatocellular carcinoma cells (Chan et al, 2008) and human breast carcinoma cells (Lee et al, 1998) showed a reduced tumor growth upon re-expression of T-cadherin. The transfection of mammary gland cells with cDNA of T-cadherin resulted in suppression of the cell proliferation in culture, which was also accompanied by transformation of the cancer cells from the invasive to the normal phenotype (Lee, 1996).…”

“…Stimulation of vascular endothelial cells and Tcadherin overexpressing HEK293 cells with plasma low density lipoproteins demonstrated the T-cadherin-induced signaling involving phospholipase C and IP3 formation, intracellular Ca 2+ mobilization, activation of tyrosine kinases Erk 1/2, and nuclear translocation of NF-kB (Kipmen-Korgun et al, 2005;Rubina et al, 2005b). However, in contrast to endothelial cells, overexpression of T-cadherin in C6 glioma (Huang et al, 2003) hepatocellular carcinoma cells (Chan et al, 2008), in immortalized keratinocytes (Mukoyama et al, 2005) and in p53(-/-) mouse embryonic fibroblasts (Chan et al, 2008) suppresses proliferation by delaying the G 2 /M phase progression. In hepatocellular carcinoma cells T-cadherin expression also increases sensitivity to TNF-induced apoptosis (Chan et al, 2008).…”

“…However, in contrast to endothelial cells, overexpression of T-cadherin in C6 glioma (Huang et al, 2003) hepatocellular carcinoma cells (Chan et al, 2008), in immortalized keratinocytes (Mukoyama et al, 2005) and in p53(-/-) mouse embryonic fibroblasts (Chan et al, 2008) suppresses proliferation by delaying the G 2 /M phase progression. In hepatocellular carcinoma cells T-cadherin expression also increases sensitivity to TNF-induced apoptosis (Chan et al, 2008). Hence, in different studies T-cadherin was shown to be involved in regulation of proliferation, apoptosis and angiogenesis in normal tissues and tumor growth.…”

Involvement of Members of the Cadherin Superfamily in Cancer

“…Highly invasive growth pattern (Berx et al 1998) Up-regulated expression Epithelial ovarian cancer (Sato et al 1998;Maruyama et al 2001;Toyooka et al 2001;Toyooka et al 2002;Roman-Gomez et al 2003;Hibi et al 2004;Sakai et al 2004;Kim et al 2005;Wang et al 2007;Brock et al 2008;Jin et al 2008;Yan et al 2008) LOH and promoter methylation Ovary Skin (BCC and SCC) Diffuse large B cell lymphoma HCC Tumor invasion; increased cell proliferation and resistance to apoptosis (Kawakami et al 1999;Takeuchi et al 2002a;Takeuchi et al 2002b;Ogama et al 2004;Chan et al 2008) Expression in intratumoral endothelium…”

Portrait of Transcriptional Expression Profiles Displayed by Different Glioblastoma Cell Lines

“…They may play an important role in the development and maintenance of tissues, and possibly are involved in the invasion and metastasis of malignant tumors. While CDH8 participates in neural circuitry, CD93 is involved in phagocytosis (Bohlson et al, 2005), CDH13 play a role in apoptosis (Chan et al, 2008), and ITGA5 in cell spreading (Fang et al, 2010). A comparative analysis of differentially expressed genes (provided by SAM) was performed with previously identified genes with TP53 binding sites; this comparison was possible by using ChIP-PET and ChIP-on-chip analyses (Smeenk et al, 2008;Wei et al, 2006).…”