57P - The expression of MMR, CD133 and the presence of p53 wt predict the response to cabazitaxel in malignant neural tumours cell lines

Abstract

BackgroundCabazitaxel is used in the treatment of metastatic prostate cancer. It is not a substrate of P-glycoprotein, which is involved in cellular detoxification of chemotherapeutic agents and in the expulsion of drugs at blood-brain barrier. Our objectives are to test Cabazitaxel in vitro in malignant neural cell lines such as glioblastoma, anaplastic glioma and neuroblastoma, and to find any predictor of response that allows us to select potential responder patients in glioblastoma multiforme and other neural tumors. MethodsCell lines A172 (glioblastoma, p53 wild type), LN229 (glioblastoma, p53 mutated), SF268 (anaplastic glioma, p53 mutated) and SK-N-SH (neuroblastoma, p53 wild type) were cultured in 48-well plates and increasing doses of Cabazitaxel were tested (0.1, 0.5, 1, 5, 10, 25, 50, 100μM). After 48hours of treatment, the proliferation values were studied by spectrophotometric assays. Also, gene expression studies of the MMR complex (miss-match repair) were performed by RT-qPCR for the primers of MLH1, MSH2, MSH3, MSH6, PMS2 genes. We also analyzed the expression of CD133 marker by RT-qPCR assays. A PCR study with Bisulfite kit was carried out to detect the promoter methylation of MGMT. ResultsIC50 values at 48hours were 13.76μm in SF268, 6.77μm in SK-N-SH, 2.88μm in LN 229 and 1.34 in A172. The expression values of MMR complex proteins were significantly higher in line A172 (relative value 1), followed by line LN229 (0.25) and negative in lines SK-N-SH and SF268. The methylation of MGMT promoter was positive in lines A172 and LN229. Finally, the expression of CD133 was higher in A172 (0.6), followed by LN229 (0.4), SK-N-SH (0.2) and SF268 (0). Pearson correlation coefficient for the relationship between CD133 expression and IC50 values is -0.96. Conclusions1. Glioblastoma, anaplastic glioma and neuroblastoma cell lines have a high sensitivity to Cabazitaxel in vitro. 2. Cell lines with MGMT methylation and MMR expression (A172 and LN 229) are the most sensitive. Of them, line A172 presents a p53 wild type, and therefore, a greater sensitivity to Cabazitaxel. 3. The expression of CD133 correlates inversely with the values of IC50 to Cabazitaxel, and may also be a predictor of response. Legal entity responsible for the studyUGR. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.