β-tubulin isotype classes II and V expression patterns in nonsmall cell lung carcinomas

Previous studies suggest that beta-tubulin isotype protein levels could be useful as indicators of nonsmall cell lung cancer (NSCLC) aggressiveness. However, measurement of protein amounts in tissue samples by staining techniques is semiquantitative at best. Since technologies for measuring mRNA levels have become more efficient and quantitative, we wanted to determine whether beta-tubulin message levels may be useful as biomarkers. Quantitative real-time RT-PCR was used to measure the seven classes of beta-tubulin isotypes, stathmin and MAP4 mRNA levels in 64 NSCLC and 12 normal lung tissue samples. We found significantly higher fractions of beta-tubulin classes II and V mRNA compared to the other isotypes in all lung tumor samples (P < 0.05). In addition, the ratio of beta-tubulin classes II/V mRNA was significantly higher in NSCLCs compared to normal lung tissues (P < 0.001). The data suggest that the ratio of beta-tubulin classes II and V mRNA could be useful as a biomarker for NSCLC tumor differentiation and/or NSCLC aggressiveness. Furthermore, the ratio of MAP4 to stathmin mRNA was found to be higher in diseased lung tissues compared to normal lung tissues, suggesting this ratio might also be used as a clinically relevant biomarker for NSCLCs.