Study on the effects and mechanisms of M2 macrophages on PYCR1-promoted biological behavior of hepatocellular carcinoma cells

Background Pyrrole-5-carboxylic acid reductase 1 (PYCR1) is a key enzyme involved in proline synthesis and is closely related to the development of hepatocellular carcinoma. This study aimed to investigate the relationship and mechanism between PYCR1 and the biological function of hepatocellular carcinoma cells under co-culture conditions with M2 tumor-associated macrophage medium. Methods THP-1 was treated with IL-4 and IL-13 for M2 polarized macrophages. Then, HCC cells were co-cultured with M2 macrophage supernatants for 48 hours. Ki67 staining was used to evaluate the proliferative capacity of the cells. Flow cytometry and Western blot were used to detect the apoptosis rate. Western blot analysis was used to detect protein levels associated with relevant signaling pathways and pathway inhibitors. In addition, Western blot analysis, ROS, and ferrous ion assay were used to detect the relationship with iron death. Results GEPIA database analysis and survival curves indicate that high PYCR1 expression is negatively correlated with patient prognosis. Co-culture of HCC cells with M2 macrophage-derived conditioned medium promotes HCC cell metastasis and EMT, while knockdown of PYCR1 alleviates the metastasis and EMT promoted by co-culture. Knockdown of PYCR1 reduces cell proliferation and increases apoptosis and ferroptosis in HCC cells. Conclusion In summary, we reported that M2 macrophage-derived conditioned medium co-cultured with hepatocellular carcinoma cells mediates PYCR1-induced cell proliferation, inhibition of apoptosis, and ferroptosis in HCC, and ultimately promotes tumor progression through the JAK2/STAT3 signaling pathway, suggesting that PYCR1 is a potential therapeutic target for HCC.