Decreased expression of the deleted in colorectal carcinoma gene in non-Hodgkin's lymphoma.

The putative tumor suppressor gene deleted in colorectal carcinoma (DCC), located on human chromosome band 18q21, is deleted or inactivated in many solid tumors. Its role in the pathogenesis of non-Hodgkin's lymphoma (NHL) has not been studied. Recently, inactivation of this gene was reported in cases of leukemia with monosomy 18. As monosomy 18 is frequently observed in low-grade NHL, we investigated the incidence of altered DCC gene expression in patients with NHL, and correlated it with the number of copies of chromosome 18. Fifteen unselected cases of NHL were studied for evidence of DCC gene expression by reverse transcriptase-polymerase chain reaction. The results were correlated with Southern blot analysis of the DCC gene and with the number of copies of chromosome 18 determined by fluorescent in situ hybridization (FISH). The controls were tissues from normal colon mucosa and normal tonsils. Eight of 15 (53%) NHL cases lacked DCC mRNA, and one expressed substantially less than normal. Southern blot analysis showed normal configuration of the DCC gene in all samples. Two copies of chromosome 18 were found in 9 of 11 samples studied by FISH: one case had a subpopulation of cells with monosomy 18 and one had trisomy 18. All controls expressed DCC. We conclude that DCC gene expression is frequently absent or decreased in NHL and may be involved in the pathogenesis of NHL. Monosomy 18 was not required for DCC inactivation.