[Cloning and characterization of MTLC, a novel gene in 6q25].

Objective: To identify and characterize laryngeal cancer related novel genes located on chromosome 6q25.

Methods: Electric hybridization was performed in human genome database using EST (expression sequence tag) as probe. Novel genes were deduced by software from positive DNA clones and their cDNAs were amplified by RT-PCR using primers designed according to the sequence of the putative genes.

Results: A novel gene was cloned successfully. The full length of this gene was about 21 kb. It contained two exons and produced a 1006 bp transcript coding a protein with 235 amino acid residues. It's 5'flanking sequence contained two binding sites of oncoprotein c-Myc, thus it was named MTLC (c-Myc target from laryngeal cancer cells). Homologous assay showed that MTLC exhibited little overall homology to known human proteins but it exhibited good overall homology to mouse MT-MC1 protein with an identity of 78%. The primary structure of MTLC protein contained a nuclear location signal motif, but it did not have other conserved domains. The results of subcellular location experiment showed that MTLC expressed in nuclei of human hepatocellular carcinoma cell line Bel7402 cells, while a wide distribution of MTLC in various tissues was demonstrated by Northern blotting.

Conclusion: MTLC may play an important role as a target gene of c-Myc and as a transcription factor in keeping the normal physiological process of cells.