Enhanced antitumor activity of atorvastatin and luteolin, with or without doxorubicin, in a solid Ehrlich carcinoma mouse model: modulation of ABC transporters, telomerase, and cancer stem cells

Abstract

This study evaluated the antitumor efficacy of atorvastatin (ATO) and luteolin (LUT), administered individually or in combination with or without doxorubicin (DOX), in mice bearing solid Ehrlich carcinoma (SEC). Additionally, we examined the effects of these treatments on ATP-binding cassette (ABC) transporters, telomerase reverse transcriptase (TERT), and cancer stem cell-related markers as potential mechanisms underlying chemoresistance. SEC tumors were induced in 70 Swiss albino female mice, which were randomly assigned into seven groups (n = 10/group): SEC control, DOX (4 mg/kg, i.p.), ATO (20 mg/kg, i.p.), LUT (40 mg/kg, i.p.), ATO+ DOX, LUT+DOX, and ATO + LUT. At the end of the study, tumors were excised, weighed, and processed for histopathological evaluation, immunohistochemical analysis of CD44, quantitative assessment of ABCB1 and ABCG2 gene expression, and protein analysis of both the non-phosphorylated (TERT) and phosphorylated form (P-TERT). Co-treated groups exhibited a greater reduction in tumor growth compared to the control and single-agent groups. These effects were accompanied by marked downregulation of ABCB1 and ABCG2 gene expression and suppression of TERT and P-TERT protein levels. Histopathological findings revealed increased apoptotic features, including karyorrhexis, and reduced mitotic activity in the co-treated groups. CD44 immunostaining was strong in the SEC and DOX groups, moderate in the ATO- or LUT-treated groups, and weak in the co-treated groups. Combining ATO or LUT with DOX enhanced antitumor efficacy and attenuated molecular determinants associated with chemoresistance in SEC. Notably, the ATO+ LUT combination without DOX demonstrated the greatest antitumor efficacy compared to DOX-containing regimens, highlighting its potential as a multi-target, non-cytotoxic therapeutic strategy.