The Combination of PD-L1 and CTLA-4 Suppression Significantly Decreased the Expression Levels of Cancer Stem Cell Factors in the Pancreatic Cancer Cell Line

Abstract

Background: It is thought that a limited number of aberrant cancer stem cells (CSCs), which encourage carcinogenesis, tumor metastasis, and treatment resistance, are the cause of pancreatic cancer, a disease with a high mortality rate. Increasing evidence shows that CSCs use immunosuppressive properties to avoid immune system identification. In Pancreatic cancer, the therapeutic consequences of the relationship between the expression of immune checkpoints such as programmed death receptor ligand-1 (PD-L1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and the presence of CSCs are poorly known. As a result, in the present investigation, we examined how the expression levels of CSCs were affected by PD-L1 and CTLA-4 knockdown using specific siRNA. Methods: Independently and together, PD-L1 and CTLA-4 siRNA were transfected into MIA PaCa-2 cells. RNA extraction and cDNA synthesis were then performed. Finally, using qRT-PCR, the gene expression levels of CSCs markers, including Nanog, CD133, CD44, and Oct-4, in transfected groups were measured. Results: In the MIA PaCa-2 cell line, siRNA-mediated inhibition of PD-L1 and CTLA-4 decreased the expression of CSC factors. Moreover, combined suppression of these two stemness-related immune checkpoints significantly decreased Nanog, CD133, CD44, and Oct-4 expression compared to inhibition of PD-L1 and CTLA-4 separately. Conclusion: Considering that the combination of PD-L1 and CTLA-4 suppression using siRNA significantly decreased the expression levels of CSCs factors, this approach may be regarded as an effective therapy for this cancer.