Identification and functional analysis of a novel cancer related gene from lung cancer and malignant mesothelioma

点击翻译按钮获取中文摘要

We identified a chromosome 3p21.3 homozygous deletion in a malignant mesothelioma cell line, NCI-H28,and found deletions of β-catenin and a novel gene, MTSK1 (tentative name). To determine whether β-catenin itself has a tumor suppressive activity against the NCI-H28 cell line, we transformed the gene into the cells. After confirmation of transcriptional activity of β-catenin with luciferase assay, we performed colony formation assay and found significant growth inhibition of the NCI-H28 cells. Using TUNEL assay, we confirmed that this inhibition was due to induction of apoptosis. Since NCI-H28 lacks β-catenin, we analyzed the function of γ-catenin under a null condition of β-catenin and found that γ-catenin also has TCF/LEF dependent transcriptional activity. Meanwhile, although we searched the predicted open reading frame of the MTSK1 gene for mutations with genomic PCR-SSCP analysis in 9 malignant mesotheliomas and 63 lung cancers, we did not find any somatic mutations. Since we discovered that MTSK1 has three alternative splicing forms, we constructed each expression vector, transformed them into NCI-H28,and confirmed expression of their products. Furthermore, we searched 154 primary lung cancers which were resected by surgery for mutations of RAS. 11 cases were found to have a KRAS mutation and, using microdissection technique, 9 tumors of them were shown to retain a wild-type KRAS allele, suggesting that expression of mutated KRAS is important for the activation of KRAS.