Through differential screening of gene expression, over 200 genes were found to be either up- or down-regulated in a hepatocellular carcinoma patient. These genes were subsequently evaluated against a panel of human HCC specimens, leading to the identification of a novel gene HEPN1. Based on the sequence of HEPN1, the new gene HEPACAM was then isolated and characterised.
Structurally, HEPACAM is a glycoprotein containing an extracellular domain with 2 Ig-like loops, a transmembrane region and a cytoplasmic domain. Matched to chromosome 11q24, gene HEPACAM is ubiquitously expressed in normal human tissues, with particularly high expression levels in the central nervous system (CNS), and is frequently suppressed in a variety of tumour types.
Functionally, HEPACAM is involved in cell-extracellular matrix interactions and growth control of cancer cells, and is able to induce differentiation of glioblastoma cells. In cell signaling, HEPACAM directly interacts with F-actin and calveolin 1, and is capable of inducing senescence-like growth arrest via a p53/p21-dependent pathway. Moreover, HEPACAM is proteolystically cleaved near the transmemberane region. These findings indicate that the new Ig-like cell adhesion molecule HEPACAM is also a tumour suppressor. HEPACAM1 is involved in negative cell cycle regulation via p53, p21 and p27 signalling but also mediates increased human breast cancer cell spread.
^ abChung Moh M, Hoon Lee L, Shen S (June 2005). "Cloning and characterization of hepaCAM, a novel Ig-like cell adhesion molecule suppressed in human hepatocellular carcinoma". Journal of Hepatology. 42 (6): 833–41. doi:10.1016/j.jhep.2005.01.025. PMID15885354.
^Moh MC, Lee LH, Yang X, Shen S (October 2003). "HEPN1, a novel gene that is frequently down-regulated in hepatocellular carcinoma, suppresses cell growth and induces apoptosis in HepG2 cells". Journal of Hepatology. 39 (4): 580–6. doi:10.1016/S0168-8278(03)00359-3. PMID12971969.
^ abcdMoh MC, Zhang C, Luo C, Lee LH, Shen S (July 2005). "Structural and functional analyses of a novel ig-like cell adhesion molecule, hepaCAM, in the human breast carcinoma MCF7 cells". The Journal of Biological Chemistry. 280 (29): 27366–74. doi:10.1074/jbc.M500852200. PMID15917256.
^ abcMoh MC, Zhang T, Lee LH, Shen S (December 2008). "Expression of hepaCAM is downregulated in cancers and induces senescence-like growth arrest via a p53/p21-dependent pathway in human breast cancer cells". Carcinogenesis. 29 (12): 2298–305. doi:10.1093/carcin/bgn226. PMID18845560.
^Lee LH, Moh MC, Zhang T, Shen S (August 2009). "The immunoglobulin-like cell adhesion molecule hepaCAM induces differentiation of human glioblastoma U373-MG cells". Journal of Cellular Biochemistry. 107 (6): 1129–38. doi:10.1002/jcb.22215. PMID19507233.
^ abMoh MC, Tian Q, Zhang T, Lee LH, Shen S (May 2009). "The immunoglobulin-like cell adhesion molecule hepaCAM modulates cell adhesion and motility through direct interaction with the actin cytoskeleton". Journal of Cellular Physiology. 219 (2): 382–91. doi:10.1002/jcp.21685. PMID19142852.
^Moh MC, Lee LH, Zhang T, Shen S (January 2009). "Interaction of the immunoglobulin-like cell adhesion molecule hepaCAM with caveolin-1". Biochemical and Biophysical Research Communications. 378 (4): 755–60. doi:10.1016/j.bbrc.2008.11.119. PMID19059381.