Recombinant Human Peroxiredoxin-5 Improves Anti-tumor Immunity by Inducing Macrophage Polarization / 中国生物化学与分子生物学报

Tumor cells can use different strategies to suppress the immune system and disable them for killing tumor cells. Previous studies have shown that recombinant human peroxiredoxin-5 (hPRDX5) can activate the normal anti-tumor immune, so as to control and eliminate the tumor cells, but its exact mechanism of action needs to be studied in depth. The study aimed to investigate whether hPRDX5 exerts its anti-tumor activity by activating or reversing the polarization state of mouse macrophages RAW264. 7 cells. The results of CCK8 showed that different doses of hPRDX5 could significantly enhance the viability of macrophage compared with the control group (P < 0. 001); The results of Nitric oxide (NO) test showed that hPRDX5 significantly enhanced NO secretion levels in RAW264. 7 cells (P < 0. 001); ELISA experiments revealed that hPRDX5 promotes TNF-α (P<0. 01) and IL-6 (P<0. 001) secretion in RAW264. 7 cells; Flow cytometry revealed that hPRDX5 increased the expression of antigen differentiation cluster (CD) 80 (P < 0. 01) and inducible nitric oxide oxide synthase (iNOS) (P < 0. 001) in RAW264. 7 cells, and reduced the expression of CD206 (P < 0. 001) in RAW264. 7 cells induced by tumor conditional culture solution (TCS); Lactate dehydrogenase (LDH) experiments revealed that hPRDX5 can increase the killing activity of mouse macrophages on mouse pancreatic cancer Panc02 cells. hPRDX5 is able to activate mouse macrophage RAW264. 7 cells, promotes its M1-type polarization, reverses M2-type polarization, and exerts antitumor activity through the immune-enhancing effect.

The antitumor activity of hPRDX5 against pancreatic cancer and the possible mechanisms

Recombinant human peroxiredoxin-5 (hPRDX5), isolated from anti-cancer bioactive peptide (ACBPs), shows a homology of 89% with goat peroxiredoxin-5 (gPRDX5) and is reported to display anti-tumor activity in vivo. Herein, we explored the effect of hPRDX5 and the responsible mechanism in treating pancreatic cancer. Tumor-bearing mice were randomly divided into normal PBS group and treatment group (n=5; 10 mg/kg hPRDX5). Flow cytometry was employed to examine lymphocytes, myeloid-derived suppressor cell subsets, and the function proteins of natural killer (NK) cells in peripheral blood, spleen, and tumor tissues of mice. Western blot was used to measure the protein expressions of the key nodes in TLR4-MAPK-NF-κB signaling pathway. The rate of tumor suppression was 57.6% at a 10 mg/kg dose in orthotopic transplanted tumor mice. Moreover, the population of CD3+CD4+T cells, NK cells, and CD3+CD8+T cells was significantly increased in the tumor tissue of the hPRDX5 group, while the proportion of granulocytic-myeloid-derived suppressor cells decreased slightly. In addition, after treatment with hPRDX5, the percentage of NK cells in blood increased more than 4-fold. Our findings indicated that hPRDX5 effectively suppressed pancreatic cancer possibly via the TLR4-MAPK-NF-κB signaling cascade; hence hPRDX5 could be a prospective immunotherapy candidate for treating pancreatic cancer.