Expression of class III b tubulin in non-small cell lung cancer is correlated with resistance to taxane chemotherapy

This study determined the prevalence and the prognostic value of the expression of microtubule components in tumors of 19 patients with non small cell lung cancer receiving taxane-based regimens. Patient samples were stained with antibodies directed against total β tubulin, classes I, II and III β tubulin isotypes, δ2 alpha tubulin, τ protein, and the P-gp protein involved in the classical multidrug resistance phenotype. All tumors were stained with pan-β tubulin antibody and class I tubulin isotype. A majority of the tumor samples expressed class II and class III, although the percentage of positive cells varied significantly between tumors. δ2 alpha tubulin, τ protein and Pgp protein were found in only one tumor sample each. Progression-free survival was shorter (41 days) in patients whose tumors expressed high levels of class III tubulin isotype in comparison to patients with low levels (288 days, p=0.02). There were 2 responses to chemotherapy among 9 patients (22%) with high levels of class III tubulin vs. 6 among 10 patients (60%) with low levels of expression (Fisher exact test: p= 0.11). These data suggest that high expression of class III tubulin by tumor cells is associated with poor prognosis in patients with NSCLC receiving a taxane-based regimen.