[The effect of PHD inhibitor on tumor microenvironment and tumor immune response]

Tumor tissue environment is generally exposed to low oxygen, nutrition depletion and high interstitial pressure condition. These circumstances are caused by vascular hyper-permeability, irregular vascularization and immature vessels. The blood vessel is important tissue structures to deliver oxygen, nutrition and so on. An abnormal blood vessel formation is a common feature of tumor tissue that were characterized by hyper-permeability, irregular vascularization, immature vessels and intravasation. Therefore, tumor tissue is exposed to low oxygen nutrition depletion and low pH due to hypoperfusion and elevated interstitial pressure. These environments are one of the reasons for chemo- and radio-resistance. Previously, we reported that prolyl hydroxylase (PHD) inhibitor induced tumor blood vessel normalization and improved tumor microenvironment in tumor mouse model. However, effects of PHD inhibitor on tumor progression is controversial. Enhanced hypoxia inducible factors (HIFs) signaling in cancer cells act to promote cancer proliferation and metastases. On the other hand, increasing of HIFs signaling in immune cells may lead to activate inflammation and elicit anti-tumor effect. We describe our study how PHD inhibitor improved tumor microenvironment and focused on tumor infiltrate immune cells were phenotypic alteration after PHD inhibitor treatment in mouse model. Our results implied that PHD inhibitor was possibly beneficial for anti-cancer therapy.