Mdr1 gene expression as a marker of treatment response in non-small cell lung cancer (NSCLC).

Abstract

e13151 Background: NSCLC is frequently chemoresistant. Multidrug resistance phenotype is involved in the development of chemoresistance. It has been related to several proteins expression, like P-glycoprotein (mdr1 gene). We examined whether elevated mdr1 expression levels in peripheral blood mononuclear cells (PBMC) predict treatment response. Methods: We studied mdr1 gene expression in PBMC of 23 patients with NSCLC, advanced stages in most of the cases, who had not received treatment previously. Blood extraction of 5ml was made to each patient before (hour 0) and after paclitaxel-carboplatin chemotherapy (hour 6). The mdr1 gene expression levels were assessed by quantitative reverse transcription polymerase chain reaction. Results: After treatment, we found mdr1 overexpression in 22 patients. Expression levels were randomly distributed, so that overexpression under 3 was considered low level of expression, and overexpression above 4 was considered high level of expression. High levels were found in 11 patients, and low levels were observed in the other 11 patients. The relationship between mdr1 expression and the treatment response was found to be not significant (p 0,68). No correlation was found between mdr1 expression and survival rate (p 0,54). No significant differences in expression were found in the other variables: gender, tobacco habit, weight loss at the diagnosis, tumor staging, and tumor histology. Conclusions: Our results suggest that the combined treatment with paclitaxel-carboplatin induces mdr1 overexpression in PBMN of patients with NSCLC, but mdr1 expression is not a predictive factor for treatment response nor a prognostic factor of the disease. No significant financial relationships to disclose.