ADAM12 in human liver cancers: TGF-β-regulated expression in stellate cells is associated with matrix remodeling

Abstract

. We have investigated ADAM expression in human liver cancers and their regulation by several cytokines involved in liver injury. Using degenerative RT-PCR, cDNA encoding sequences for ADAM9 and ADAM12 were identified in human activated hepatic stellate cells (HSCs). Northern blot analyses showed that HSCs, but not hepatocytes, expressed transcripts for ADAM9 messenger RNA (mRNA) and both the long and short forms of ADAM12. This expression was associated with the transition from quiescent to activated state of rat HSCs and markedly increased in human livers with cirrhosis. ADAM12 but not ADAM9 expression was up-regulated by transforming growth factor ␤ (TGF-␤) in human activated HSCs. The PI3K inhibitor LY294002 and the mitogen-activated protein kinase kinase (MEK) inhibitor UO126 prevented ADAM12 induction by TGF-␤, suggesting the involvement of PI3K and MEK activities. In vivo, the steady-state of both ADAM9 and ADAM12 mRNA levels was nearly undetectable in both normal livers and benign tumors and increased in hepatocellular carcinomas (up to 3-and 6-fold, respectively) and liver metastases from colonic carcinomas (up to 40-and 60-fold, respectively). The up-regulation of both ADAM9 and ADAM12 was correlated with an increase in matrix metalloproteinase 2 expression and activity. In conclusion, in liver cancers ADAM9 and ADAM12 expression is associated with tumor aggressiveness and progression. I ncreased expression and activities of matrix metalloproteinase (MMP) has been shown widely in malignant phenotypes facilitating the breakdown of extracellular matrix component and cell evasion, but also unmasking bioactive cryptic fragments and releasing active growth factors which, in turn, favor tumor growth. 1 The ADAMs (a disintegrin and metalloproteinase-containing proteins) are a family of multidomain glycoproteins highly homologous to the class III snake venom metalloprotease-disintegrins. 2 The common extracellular part of the proteins includes a regulatory prodomain and metalloprotease, disintegrin-like and cystein-rich domains. Further, ADAMs are characterized by an epidermal growth factor (EGF)-like domain, a transmembrane domain, and a cytoplasmic tail. More than 30 members have been identified in the ADAM family with a broad tissue distribution and have been involved in specific cellular processes including sperm-egg interaction, 3 myocyte fusion, 4 neurogenesis, 5 and adipogenesis. 6 Recently, ADAM12 gene therapy was shown to rescue the pathology of mdx-gene deficient dystrophic mice.

Expression of a disintegrin and metalloprotease (ADAM and ADAMTS) enzymes in human non-small-cell lung carcinomas (NSCLC)

“…We demonstrate in the present paper that cultured BZR lung-derived cancer cell lines expressed ADAM-12 mRNA, while 16-HBE and BEAS-2B cells derived from normal epithelial cells did not express significant levels of ADAM-12 mRNA. Others have reported an overexpression of ADAM-12 in liver carcinomas (Le Pabic et al, 2003), and its levels in urine from patients have been correlated with survival in breast cancer (Roy et al, 2004). These data, taken together with the faint expression of ADAM-12 mRNA levels in healthy lung extracts, indicate that tumour cells are probably the main producer of ADAM-12 in our experimental conditions.…”

“…Indeed, ADAMs and ADAMTS belong to the adamalysin family, related to snake venom proteases, among which many members are implicated in different loops of reciprocal interactions with some mediators of inflammation such as TNF-a (Rosendahl et al, 1997;Moss et al, 2001) and growth factors including TGF-a and -b (Hinkle et al, 2003;Le Pabic et al, 2003).…”

IL-17A Plays a Critical Role in the Pathogenesis of Liver Fibrosis through Hepatic Stellate Cell Activation

“…Primary mouse HSCs were isolated from livers of C57BL/6 mice according to a modified method described previously (13). In brief, livers were perfused in situ with 45 ml Life Technologies Liver Perfusion Media (Invitrogen, Carlsbad, CA) followed by 45 ml Life Technologies Liver Digestion Media (Invitrogen).…”

Emerging roles of ADAM and ADAMTS metalloproteinases in cancer

“…ADAMs are also implicated in hepatocellular carcinoma development [136]. Indeed, ADAM-17 contributes to EGFRligand release and induction of cell proliferation and invasion [137].…”