1-Pyrroline-5-carboxylate inhibit T cell glycolysis in prostate cancer microenvironment by SHP1/PKM2/LDHB axis.

ABSTRACT

BACKGROUND: Our previous studies demonstrated that 1-Pyrroline-5-carboxylate (P5C) released by prostate cancer cells inhibits T cell proliferation and function by increasing SHP1 expression. We designed this study to further explore the influence of P5C on T cell metabolism, and produced an antibody for targeting P5C to restore the functions of T cells. METHOD: We co-immunoprecipated SHP1 from T cells and analyzed the proteins that were bound to it using liquid chromatography mass spectrometry (LC/MS-MS). The influence of P5C on T cells metabolism was also detected by LC/MS-MS. Seahorse XF96 analyzer was further used to identify the effect of P5C on T cells glycolysis. We subsequently designed and produced an antibody for targeting P5C by monoclonal technique and verified its effectiveness to restore the function of T cells in vitro and in vivo. RESULT: PKM2 and LDHB bind SHP1 in T cells, and P5C could increase the levels of p-PKM2 while having no effect on the levels of PKM2 and LDHB. We further found that P5C influences T cell energy metabolism and carbohydrate metabolism. P5C also inhibits the activity of PKM2 and decreases the content of intracellular lactic acid while increasing the activity of LDH. Using seahorse XF96 analyzer, we confirmed that P5C remarkably inhibits glycolysis in T cells. We produced an antibody for targeting P5C by monoclonal technique and verified that the antibody could oppose the influence of P5C to restore the process of glycolysis and function in T cells. Meanwhile, the antibody also inhibits the growth of prostate tumors in an animal model. CONCLUSION: Our study revealed that P5C inhibits the process of glycolysis in T cells by targeting SHP1/PKM2/LDHB complexes. Moreover, it is important that the antibody for targeting P5C could restore the function of T cells and inhibit the growth of prostate tumors.