Concomitant blockade of A2AR and CTLA-4 by siRNA-loaded polyethylene glycol-chitosan-alginate nanoparticles synergistically enhances antitumor T-cell responses.

Inhibitory immune checkpoint (ICP) molecules are important immunosuppressive factors in a tumor microenvironment (TME). They can robustly suppress T-cell-mediated antitumor immune responses leading to cancer progression. Among the checkpoint molecules, cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) is one of the critical inhibitors of anticancer T-cell responses. Besides, the expression of adenosine receptor (A2AR) on tumor-infiltrating T cells potently reduces their function. We hypothesized that concomitant silencing of these molecules in T cells might lead to enhanced antitumor responses. To examine this assumption, we purified T cells from the tumor, spleen, and local lymph nodes of CT26 colon cancer-bearing mice and suppressed the expression of A2AR and CTLA-4 using the small interfering RNA (siRNA)-loaded polyethylene glycol-chitosan-alginate (PCA) nanoparticles. The appropriate physicochemical properties of the produced nanoparticles (NPs; size of 72 nm, polydispersive index [PDI] < 0.2, and zeta potential of 11 mV) resulted in their high efficiency in transfection and suppression of target gene expression. Following the silencing of checkpoint molecules, various T-cell functions, including proliferation, apoptosis, cytokine secretion, differentiation, and cytotoxicity were analyzed, ex vivo. The results showed that the generated nanoparticles had optimal physicochemical characteristics and significantly suppressed the expression of target molecules in T cells. Moreover, a concomitant blockade of A2AR and CTLA-4 in T cells could synergistically enhance antitumor responses through the downregulation of PKA, SHP2, and PP2Aα signaling pathways. Therefore, this combination therapy can be considered as a novel promising anticancer therapeutic strategy, which should be further investigated in subsequent studies.

Ghasemi-Chaleshtari M ，Kiaie SH ，Irandoust M ，Karami H ，Nabi Afjadi M ，Ghani S ，Aghaei Vanda N ，Ghaderi Sede MJ ，Ahmadi A ，Masjedi A ，Hassannia H ，Atyabi F ，Hojjat-Farsangi M ，Namdar A ，Ghalamfarsa G ，Jadidi-Niaragh F ... -  《-》

Downregulation of A2AR by siRNA loaded PEG-chitosan-lactate nanoparticles restores the T cell mediated anti-tumor responses through blockage of PKA/CREB signaling pathway.

Adenosine and its receptors are novel promising targets for cancer immunotherapy. In here, we aimed to evaluate the efficacy of Polyethylene glycol (PEG)-chitosan-lactate (PCL) nanoparticles (NPs) loaded with A2AR-specific siRNA for interfering with differentiation and function of T cells derived from the 4T1 breast tumor-bearing Balb/C mice, ex vivo. The size of synthesized NPs was about 100 nm in association with low polydispersive index (pdi < 0.3) and a zeta potential of 11 mV. In association with good physicochemical characteristics, NPs exhibited high transfection efficiency in T cells and low toxicity on the various cell lines. T cells were treated with A2AR siRNA-loaded NPs demonstrated suppressed expression of A2AR which was associated with increased proliferation, reduced apoptosis, increased production of inflammatory and reduced secretion of inhibitory cytokines compared to untreated T cells. Moreover, differentiation of conventional T cells purified from tumor-bearing mice to regulatory T cells (Treg) was blocked using A2AR-specific siRNA-loaded NPs. These immune-stimulatory effects were in part through downregulation of protein kinase A/cAMP-response element binding protein (PKA/CREB) axis and upregulation of nuclear factor-κB (NF-κB).

Masjedi A ，Hassannia H ，Atyabi F ，Rastegari A ，Hojjat-Farsangi M ，Namdar A ，Soleimanpour H ，Azizi G ，Nikkhoo A ，Ghalamfarsa G ，Mirshafiey A ，Jadidi-Niaragh F ... -  《-》

Simultaneous silencing of the A2aR and PD-1 immune checkpoints by siRNA-loaded nanoparticles enhances the immunotherapeutic potential of dendritic cell vaccine in tumor experimental models.

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.

Karoon Kiani F ，Izadi S ，Ansari Dezfouli E ，Ebrahimi F ，Mohammadi M ，Chalajour H ，Mortazavi Bulus M ，Nasr Esfahani M ，Karpisheh V ，Mahmoud Salehi Khesht A ，Abbaszadeh-Goudarzi K ，Soleimani A ，Gholizadeh Navashenaq J ，Ahmadi M ，Hassannia H ，Hojjat-Farsangi M ，Shahmohammadi Farid S ，Hashemi V ，Jadidi-Niaragh F ... -  《-》

Silencing adenosine A2a receptor enhances dendritic cell-based cancer immunotherapy.

Overexpression of adenosine in the tumor region leads to suppression of various immune cells, particularly T cells through ligation with adenosine 2a receptor (A2aR). In this study, we intended to increase the efficacy of tumor lysate-loaded DC vaccine by silencing the expression of A2aR on T cells through the application of A2aR-specific siRNA-loaded PEG-chitosan-lactate (PCL) nanoparticles (NPs) in the 4T1 breast tumor-bearing mice. Combination therapy by DC vaccine and siRNA-loaded NPs markedly induced tumor regression and increased survival time of mice. These ameliorative effects were partly via downregulation of immunosuppressive cells, increased function of cytotoxic T lymphocytes, and induction of immune-stimulatory cytokines. Moreover, combination therapy could markedly suppress angiogenesis and metastasis processes. These results imply the efficacy of novel combination therapy for the treatment of breast cancer by using A2aR siRNA-loaded NPs and DC vaccine which can be translated into the initial phase of clinical trials in the near future.

Masjedi A ，Ahmadi A ，Ghani S ，Malakotikhah F ，Nabi Afjadi M ，Irandoust M ，Karoon Kiani F ，Heydarzadeh Asl S ，Atyabi F ，Hassannia H ，Hojjat-Farsangi M ，Namdar A ，Ghalamfarsa G ，Jadidi-Niaragh F ... -  《-》

Blockade of CTLA-4 increases anti-tumor response inducing potential of dendritic cell vaccine.

The immunosuppressive state of the tumor microenvironment diminishes the efficacy of dendritic cell (DC)-based cancer immunotherapy. Inhibitory immune checkpoint molecules expressed on tumor-infiltrating T lymphocytes, such as cytotoxic T-lymphocyte antigen 4 (CTLA-4) molecules are one of the main barriers in priming T cells by DCs. Therefore, it seems that blockade of such molecules facilitates the T cells activation by the DC vaccine. In this study, we intended to suppress the expression of CTLA-4 molecule on tumor-infiltrating T cells by siRNA-loaded chitosan-lactate (CL) nanoparticles to facilitate priming anti- tumor T cells by tumor lysate-loaded DC vaccine. Nanoparticles (NPs) have also provided an opportunity for specific drug delivery into the tumor site. CL NPs exhibited favorable physicochemical characteristics (size about 75 nm, polydispersive index<0.2, and a zeta potential about 14), which were associated with a high transfection rate and low toxicity. Moreover, the administration of anti-CTLA-4 siRNA-loaded NPs into CT26 and 4 T1 tumor -bearing mice led to the downregulation of CTLA-4 on tumor -infiltrating T cells, which was associated with tumor regression and increased mice survival. Moreover, while the treatment of tumor -bearing mice with DC vaccine had mild therapeutic outcomes, its combination with siRNA-loaded NPs may exhibit synergistic anti- tumor effects. This possible synergistic ameliorating effect is achieved through the reduction of immunosuppressive cells, the improved cytotoxicity of T lymphocytes, decreased inhibitory and increased inflammatory cytokines, and reduced angiogenesis and metastasis processes. These results indicate that the silencing of CTLA-4 can potentiate the T cell priming capacity of the DC vaccine, proposing a practical anti-cancer therapeutic approach.

Esmaily M ，Masjedi A ，Hallaj S ，Nabi Afjadi M ，Malakotikhah F ，Ghani S ，Ahmadi A ，Sojoodi M ，Hassannia H ，Atyabi F ，Namdar A ，Azizi G ，Ghalamfarsa G ，Jadidi-Niaragh F ... -  《-》