The deleted in colorectal cancer (DCC) gene: a candidate tumour suppressor gene encoding a cell surface protein with similarity to neural cell adhesion molecules.

Chromosome 18q is among the regions thought to harbour a tumour suppressor gene(s) that is frequently inactivated by LOH during the development of several cancer types, including those of the gastrointestinal tract. In addition, colorectal cancers with 18q LOH have been shown to have a more aggressive clinical behaviour than those without 18q LOH. A candidate tumour suppressor gene from 18q, called DCC, has been identified. The DCC gene is contained within the common region of LOH on 18q, its expression is markedly decreased or absent in the majority of colorectal cancers and cell lines and somatic mutations within the DCC gene have been identified in a subset of cases. Thus, DCC represents the strongest candidate tumour suppressor gene on 18q. At present, however, many questions remain regarding the mechanisms underlying the inactivation of DCC and its decreased expression in cancers. The predicted structural similarity of DCC to the NCAMs suggests that it may function through cell-cell and/or cell-extracellular matrix interactions; however, little is known regarding the specific cellular function(s) of DCC. Many reports have detailed the alterations in phenotype observed in cancer cells, including changes in cell morphology and tissue architecture, loss of differentiated phenotype, decreased cell adhesion and aggregation, increased motility and invasive behaviour. These altered properties are likely to account in part for the invasive and metastatic properties of cancer cells in the patient. It is hoped that further studies will identify the means by which DCC inactivation may contribute to the altered growth properties of advanced cancer cells.