P108

Abstract

Glioblastomas (GBL) are most aggressive brain tumors in adults. They are often radio- and chemotherapy resistant. The standard therapy of GBL includes surgery followed by radiotherapy with concomitant chemotherapy with temozolomide named temodal (imidazotetrazine derivative). Methylation of the O6-methylguanine-DNA-methyltransferase (MGMT) gene promoter is considered as predictor of better outcome of temodal therapy in comparison with the cases without MGMT promoter methylation (Stupp et al., 2009). The aim of this study is finding of additional predictors of temozolomide therapy effectiveness. Materials and methods: We obtained primary cultures of GBL. The rate of GBL sensitivity to temozolomide was revealed by MTT test. Expression of multidrug resistance genes and genes which mediate temozolomide sensitivity (YB1, MDR1, MRP1, LRP, BCRP and MGMT) was determined by real time PCR. Protein localization and expression was revealed by immunohistochemical technique. Results: We developed 14 primary GBL cultures. Staining for nestin was used for demonstration of neuronal origin of cell cultures. Analysis of gene expression and the rate of cell proliferation of the cultures showed that the rate of YB1 gene expression in slow proliferating cultures is significantly lower than in quickly proliferating cell populations. Cell cultures differed in temodal sensitivity 2–2.5-fold. We analyzed whether GBL cell sensitivity to temodal and the rate of several genes’ expression are correlated. We did not find the correlation between cell temodal sensitivity and the rate of MGMT gene expression. These data are in accordance with some results of another authors (Mullins et al., 2013; Brennan et al., 2013). However, we revealed positive correlation of the temodal sensitivity of GBL cultures and MVP/LRP expression (r = 0.5592, p = 0.04). We found also the trend to negative correlation between GBL temodal sensitivity and YB1 gene expression (r = −0.43602, p = 0.02) as well as MDR1 expression (r = −0.4195, p = 0.02). Conclusion: The rate of temodal sensitivity of GBL primary cultures is connected with the rate of the expression of MVP/LRP, YB1 and MDR1genes. It is likely that YB-1 protein affects temodal sensitivity by influence on DNA reparation. YB1 could also have an effect on MDR1 expression. MVP/LRP expression is independent factor of GBL prognosis. This paper was completed with partial support from the Russian Foundation for Basic Research – Russia (Grant No. 23-04-40204).