Mohsen Rashid
1 
, Mina Ramezani
2, Ommoleila Molavi
3, Zeinab Ghesmati
4, Behzad Baradaran
5, Mehdi Sabzichi
6, Fatemeh Ramezani
1* 1 Department of Molecular Medicine, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
2 Department of Anatomical Sciences, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
3 Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
4 Department of Medical Biotechnology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
5 Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
6 School of Pharmacy and Biomedical Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth, United Kingdom
Abstract
Introduction: The immunosuppressive context of the tumor microenvironment (TME) is a significant hurdle in breast cancer (BC) treatment. Combinational therapies targeting cancer core signaling pathways involved in the induction of TME immunosuppressive milieu have emerged as a potent strategy to overcome immunosuppression in TME and enhance patient therapeutic outcomes. This study presents compelling evidence that targeting hypoxia-inducible-factor-1 alpha (Hif-1α) alongside chemotherapy and immune-inducing factors leads to substantial anticancer effects through modulation of TME.
Methods: Chitosan (Cs)/Hif-1alpha siRNA nano-complex was synthesized by siRNA adsorption methods. Nanoparticles were fully characterized using dynamic light scattering and scanning electron microscope. Cs/Hif-1α siRNA cytotoxicity was measured by MTT assay. The anticancer effects of the combinational therapy were assessed in BALB/c bearing 4T1 tumors. qPCR and western blotting were applied to assess the expression of some key genes and proteins involved in the induction of immunosuppression in TME.
Results: Hif-1α siRNA was successfully loaded in chitosan nanoparticles. Hif-1α siRNA nanocomplexes significantly inhibited the expression of Hif-1α. Triple combination therapy (Paclitaxel (Ptx) + Imiquimod (Imq) + Cs/Hif-1α siRNA) inhibited tumor growth and downregulated cancer progression genes while upregulating cellular-immune-related cytokines. Mice without Cs/Hif-1α siRNA treatments revealed fewer cancer inhibitory effects and more TME immunosuppressive factors. These results suggest that the inhibition of Hif-1α effects synergize with Ptx and Imq to inhibit cancer progression more significantly than other combinational treatments.
Conclusion: Combining Hif-1α siRNA with Ptx and Imq is promising as a multimodality treatment. It has the potential to attenuate TME inhibitory effects and significantly enhance the immune system's ability to combat tumor cell growth, offering an inspiration of hope in the fight against BC.