A new strategy for enhancing antitumor immune response using dendritic cells loaded with chemo-resistant cancer stem-like cells in experimental mice model

Background and aim: Cancer stem cells (CSCs) are rare cell population present in the tumor bulk that are thought to be the reason for treatment failure following chemotherapy in terms of their intrinsic chemo-resistance. Our study aimed to develop an effective therapeutic strategy to target chemo-resistant cancer stem - like cells population in solid Ehrlich carcinoma (SEC) mice model using dendritic cells (DCs) loaded with enriched tumor cells lysate bearing CSC-like phenotype as a vaccine. Materials and methods: Ehrlich carcinoma cell line was exposed to different concentrations of cisplatin, doxorubicin, or paclitaxel. Drug treatment that resulted in drug surviving cells with the highest expression of CSCs markers (CD44(+)/CD24(-)) was selected to obtain enriched cell cultures with resistant CSCs population. Dendritic cells were isolated from mice bone marrow, pulsed with enriched CSC lysate, analyzed and identified (CD11c, CD83 and CD86). SEC-bearing mice were treated with loaded or unloaded DCs either as single treatment or in combination with repeated low doses of cisplatin. IFN-gamma serum level and p53gene expression in tumor tissues were determined by ELISA and real-time PCR, respectively. Results and conclusion: The results revealed that vaccination with CSC loaded DCs significantly reduced tumor size, prolonged survival rate, increased IFN-gamma serum levels, and upregulated p53gene expression in SEC bearing mice. These findings were more evident and significant in the group co-treated with CSC-DC and cisplatin rather than other treated groups. This study opens the field for combining CSC-targeted immunotherapy with repeated low doses chemotherapy as an effective strategy to improve anticancer immune responses.