Significant up-regulation of a novel gene, CLCP1, in a highly metastatic lung cancer subline as well as in lung cancers in vivo

Most lung cancer patients are unfortunately uncurable and die because of widespread metastases, thus indicating the importance of identification of molecules with a crucial role in this process. Our previous expression profiling analysis of a highly metastatic lung cancer cell line, NCI-H460-LNM35, and its parental low metastatic line, NCI-H460-N15, revealed significant up-regulation of both known and unknown genes in LNM35. In this study, we describe the isolation and detailed characterizations of a novel gene, named CLCP1, which corresponds to one of such expression sequence tags with up-regulated expression in LNM35. The CLCP1 gene was found to encode a protein with 775 amino acids with structural similarities to, but distinct from neuropilins, cell surface receptors for VEGF₁₆₅ and semaphorins. Notably, CLCP1 was shown to be upregulated not only in LNM35 in association with its acquisition of metastatic phenotype during in vivo selection, but also in a significant fraction of lung cancers in vivo with high frequency in metastatic lesions, warranting future studies for a better understanding of the molecular mechanisms of lung cancer metastasis.