Molecular cloning and characterization of LCRG1, a novel gene localized to the tumor suppressor locus D17S800–D17S930

Laryngeal carcinoma (LC) is the most commonly diagnosed malignancy and recently the incidence of this disease has increased. By means of the mRNA differential display method we identified a cDNA, Laryngeal carcinoma related gene 1 (LCRG1), which has significantly reduced expression in 40% (12/30) of primary LCs and in 6 of 10 various cancer cell lines. Northern Blot analysis showed that LCRG1 was expressed more abundantly in human heart, pancreas, skeletal muscle, and in murine testis, liver, brain and heart than in other tissues. The cDNA sequence of this gene is identical to part of the sequence of PAC HCIT75G16 clone (GenBank accession No. AC003042) from the chromosome band 17q12–21.1 which is one of the most common loss of heterozygosity (LOH) regions involved in LC, prostate cancer, etc. This gene is composed of six exons and spans about 60 kb of genomic DNA with a 3.4 kb mature transcript. The alignment of this gene with STS markers localized the gene to the previously identified tumor-suppressor locus D17S800–D17S930. The putative protein encoded by this gene is 288 amino acid with one potential site for phosphorylation by casein kinase II and no significant homology to any known proteins in the public databases. The primary tumor suppressive functions (proliferation rate,soft agar growth and tumor formation) were observed in a LC cell line (Hep-2) by lipofectin transfection. Together these data strongly suggest a potential role of LCRG1 contributing to the development of LC.