Molecular profiling of genes in squamous cell lung carcinoma in Asian Indians

Early metastasis and a poor five-year survival make lung cancer the leading cause of cancer related deaths worldwide. The clinical profile of lung cancer patients in India differs from the West as they present earlier, with squamous cell carcinoma being the commonest histological type. We compared gene expression profiles in primary lung squamous cell carcinoma (LSCC) and matched normal lung tissues in Asian Indians. Using suppression subtractive hybridization, two subtracted cDNA libraries containing differentially expressed genes in the tumors were constructed. Differential expression was confirmed by reverse Northern blot analysis. DNA of confirmed clones was sequenced and subjected to GenBank Blast searches. RNA expression levels were then analyzed by Northern blotting and validated by semiquantitative RT-PCR (in 10 cases of NSCLC). Seventeen differentially expressed gene cDNA fragments of LSCC were analyzed. The differentially expressed genes included those associated with cellular metabolism, cell-cycle, -structure, -adhesion, transcription, proliferation, apoptosis and signal transduction. The study provided first evidence that KIAA0767, a Death Inducing Protein, a novel p53 independent target of E2F1, and Geminin, an inhibitor of DNA replication are differentially expressed in LSCC. Identification of the differentially expressed genes in lung cancer in this study may serve as better molecular markers for early diagnosis and identifying novel intervention sites for anticancer therapy.