RESUMO
Following various immunotherapies, lack of proper anti-tumor immune responses is considered a significant problem in novel cancer therapeutic approaches. The expression of inhibitory checkpoint molecules on tumor-infiltrating T cells is one of the main reasons for the ineffectiveness of various immunotherapies. Therefore, we decided to inhibit two of the most important immune checkpoints expressed on tumor-associated T cells, PD-1 and A2aR. Ligation of PD-1 with PD-L1 and A2aR with adenosine significantly suppress T cell responses against tumor cells. Whitin tumors, specific inhibition of these molecules on T cells is of particular importance for successful immunotherapy as well as the elimination of treatment-associated side-effects. Thus, in this study, superparamagnetic iron oxide (SPION) nanoparticles (NPs) were covered by chitosan lactate (CL), functionalized with TAT peptide, and loaded with siRNA molecules against PD-1 and A2aR. Appropriate physicochemical properties of the prepared NPs resulted in efficient delivery of siRNA to tumor-derived T cells and suppressed the expression of A2aR and PD-1, ex vivo. T cell functions such as cytokine secretion and proliferation were considerably enhanced by the downregulation of these molecules which led to an increase in their survival time. Interestingly, treatment of CT26 and 4T1 mouse tumors with siRNA-loaded NPs not only inhibited tumor growth but also markedly increased anti-tumor immune responses and survival time. The results strongly support the efficacy of SPION-CL-TAT NPs loaded with anti-PD-1/A2aR siRNAs in cancer therapy and their further development for cancer patients in the near future.
Assuntos
Neoplasias da Mama/terapia , Neoplasias Colorretais/terapia , Nanopartículas/administração & dosagem , Receptor de Morte Celular Programada 1/antagonistas & inibidores , RNA Interferente Pequeno/genética , Receptor A2A de Adenosina/química , Vacinas/administração & dosagem , Animais , Apoptose , Neoplasias da Mama/genética , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Proliferação de Células , Quitosana/química , Neoplasias Colorretais/genética , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/patologia , Terapia Combinada , Células Dendríticas/imunologia , Células Dendríticas/transplante , Feminino , Humanos , Imunoterapia , Ácido Láctico/química , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Nanopartículas/química , Receptor de Morte Celular Programada 1/imunologia , Receptor A2A de Adenosina/genética , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
AIMS: Despite extensive efforts to find new treatments, chemotherapy is still one of the first and foremost choices for cancer treatment. The main problems of using these drugs are the resistance of cancer cells and reducing their sensitivity to chemotherapy as well as the side effects of their systemic administration. Because STAT3 plays a very important role in the survival and susceptibility of cancer cells to apoptosis, we hypothesized that suppression of STAT3 expression could induce greater susceptibility to DOX-induced cancer cell death. MATERIALS AND METHODS: We used pegylated chitosan lactate nanoparticles (NPs) functionalized by TAT peptide and folate to deliver STAT3 siRNA and DOX to cancer cells simultaneously, both in vitro and in vivo. KEY FINDINGS: The results showed that NPs could effectively deliver siRNA and DOX to cancer cells, which was associated with suppression of STAT3 expression and increased induction of DOX-mediated cell death. Concomitant delivery of DOX and STAT3 siRNA also suppressed tumor growth in 4T1 and CT26 cancer models, which was associated with induction of anti-tumor immune responses. SIGNIFICANCE: These findings suggest that the use of NPs can be an effective strategy for the targeted delivery of STAT3-specific siRNA/DOX to cancer cells.