HEPACAM


Gene HEPACAM*, named based on its original site of identification - hepatocytes and the nature of its protein product - a cell adhesion molecule, was first discovered and characterised in human liver and reported by Shali Shen in 2005. The gene encodes a protein of 416 amino acids, designated as hepaCAM**, which is a new member of the immunoglobulin superfamily of cell adhesion molecules modulating cell-matrix adhesion and migration, and b) inhibiting cancer cell growth.

Discovery

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.

Characteristics and functions

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, 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.

Other names

  1. glialCAM, which was cloned from a human brain cDNA library in 2008 and found to be identical to hepaCAM; and
  2. HEPACAM1, when HEPACAM2 emerged in 2010.

    About HEPACAM 2

and their metastases are characterized by decreased HEPACAM2 but unchanged HEPACAM2 expression levels when compared to normal glands.