Combined silencing expression of MGMT with EGFR or galectin-1 enhances the sensitivity of glioblastoma to temozolomide

Abstract

For several years, the first line of treatment of glioblastoma (GB) patients is based on surgical resection followed by fractioned radiotherapy with concomitant and adjuvant chemotherapy with temozolomide (TMZ). The effectiveness of this treatment is very limited due to the development by tumor cells of mechanisms of resistance to TMZ such as over-expression of O6-methylguanine DNA methyltransferase (MGMT), epidermal growth factor receptor (EGFR) and galectin-1. In this study, we hypothesized that the targeting of MGMT, EGFR and galectin-1 (alone or in combination) by specifics siRNAs carried by chitosan-lipid nanocapsules (chitosan-LNCs) could enhance the sensitivity of U87MG cells to TMZ. We showed in vitro that (i) anti-MGMT and (ii) anti-EGFR or anti-galectin-1 siRNAs decreased significantly the expression of their corresponding proteins and increased the sensitivity of U87MG cells to TMZ. Additionally, the sensitivity of U87MG/MGMT- cells to TMZ was significantly increased when anti-EGFR and anti-galectin-1 siRNAs were combined with a percentage of living cells of 17.8±1.6% at 0.5 mg/mL concentration of TMZ. The combination of anti-MGMT siRNAs with either anti-EGFR or anti-galectin-1 siRNAs enhanced the sensitivity of U87MG/MGMT+ cells to TMZ in comparison to their separately use. No difference was observed between the association of the three siRNAs and other associations. At 0.5 mg/mL concentration of TMZ, the percentage of living cells decreased from 55.1±1.9% to 36.0±4.1% for anti-MGMT alone and the combination of anti-MGMT/anti-galectin-1/anti-EGFR siRNAs, respectively. These siRNA nanovectors represent a good alternative to enhance the effectiveness of the standard treatment of GB. This method could be implemented in future preclinical models for experimental cancer treatment of GB.