Isolation of a novel human lung-specific gene, LUNX, a potential molecularmarker for detection of micrometastasis in non-small-cell lung cancer

We have isolated a novel human lung-specific gene, LUNX (lung-specific X pr otein), by differential-display mRNA analysis. The full-length cDNA contain ed 1,015 nucleotides including an open reading frame of 768 nucleotides enc oding 256 amino acids. We localized the gene to chromosomal region 20p1.1-q 12 by radiation hybrid mapping. Using an RT-PCR assay specific for LUNX mRN A, 35 non-small-cell lung-cancer (NSCLC) tumors and 0 of 16 normal lymph no des were positive. Furthermore, LUNX mRNA expression was enhanced in 26 (84 %) of 31 NSCLC tumors vs. corresponding cancer-free lung tissues by semi-qu antitative analyses with multiplex RT-FCR. We assessed the possibility of L UNX mRNA as a molecular marker for detection of micrometastasis in dissecte d lymph nodes obtained from 20 patients with NSCLC tumors. LUNX mRNA was de tected in 16 (80%) of 20 histologically positive lymph nodes and 21 (25%) o f 84 histologically negative lymph nodes. Comparative analyses of the conve ntional histological examination and the RT-PCR detection assay for LUNX mR NA showed that the detection rate of metastases in lymph nodes by the RT-PC R assay was higher in 12 and consistent in 6 of the total 20 NSCLC patients . We demonstrate that the LUNX RT-PCR assay is a potential diagnostic metho d for detection of micrometastases in lymph nodes of NSCLC patients. (C) 20 01 Wiley-Liss, Inc.