The Effect of Therapy Regimen on Antitumor Efficacy of the Nanosomal Doxorubicin against Rat Glioblastoma 101.8.

One of the key problems of glioblastoma treatment is the low effectiveness of chemotherapeutic drugs. Incorporation of doxorubicin into PLGA nanoparticles allows increasing the antitumor effect of the cytostatics against experimental rat glioblastoma 101.8. Animal survival, tumor volume, and oncogene expression in tumor cells were compared after early (days 2, 5, and 8 after tumor implantation) and late (days 8, 11, and 14) start of the therapy. At late start, a significant increase in the expression of oncogenes Gdnf, Pdgfra, and Melk and genes determining the development of multidrug resistance Abcb1b and Mgmt was revealed. At early start of therapy, only the expression of oncogenes Gdnf, Pdgfra, and Melk was enhanced. Early start of treatment prolonged the survival time and increased tumor growth inhibition by 141.4 and 95.7%, respectively, in comparison with the untreated group; these differences were not observed in the group with late start of therapy. The results indicate that the time of initiation of therapy is a critical parameter affecting the antitumor efficacy of DOX-PLGA.

Changes in Oncogene Expression in Experimental Glioblastoma 101.8 Rats during Therapy with PLGA Nanoparticles Loaded with Doxorubicin.

We compared the expression of the main glioblastoma oncogenes during therapy with doxorubicin (Dox) and Dox in nanoparticles based on a copolymer of lactic and glycolic acids (Dox-PLGA) at a delayed start of treatment. Late initiation of Dox-PLGA therapy of glioblastoma showed an increase in the expression of multiple drug resistance genes, such as Abcb1b and Mgmt, and a decrease in Sox2 expression. Increased expression of other oncogenes (Melk, Wnt3, Gdnf, and Pdgfra) were observed during both Dox and Dox-PLGA therapy. These changes indicate increased tumor aggressiveness and its resistance to cytostatics at the late start of therapy.