Choice of endogenous control for gene expression in nonsmall cell lung cancer

This study attempts to identify a suitable endogenous control gene for real-time RT-PCR in nonsmall cell lung cancer (NSCLC) tissues. Expression of seven common endogenous control genes (glyceraldehyde-3-phosphate dehydrogenase (GAPDH), v-abl Abelson murine leukaemia viral oncogene homologue 1, beta-2-microglobulin, hypoxanthin phosphoribosyltransferase 1 (HPRT1), phosphoglycerate kinase 1, peptidylprolyl isomerase A, and ribosomal protein, large, P0) in 18 heterogenous NSCLC tumour specimens, 10 normal lung tissues and six NSCLC cell lines were analysed by quantitative RT-PCR. The variances and correlation coefficients of cycle threshold (Ct) value of each control gene in three tissue groups and subgroups were compared. The difference and correlation coefficients between the Ct value for each control gene and the mean Ct value of the remaining control genes were calculated. The GAPDH gene transcript showed the least variance and linear regression analysis demonstrated that GAPDH and HPRT had the strongest correlation in pooled tumour and normal lung tissues. Furthermore, GAPDH expression value showed stringent correlation and had the lowest difference with the mean expression value of the remaining endogenous control genes. Among the seven common endogenous control genes, glyceraldehyde-3-phosphate dehydrogenase is the most suitable for quantitative RT-PCR reaction in nonsmall cell lung cancer tissue samples.