Pkc ζ In Prostate Cancer Cells Represses The Recruitment And M2 Polarization Of Macrophages In The Prostate Cancer Microenvironment

Background and objectiveProstate cancer(PCa)has become the second most commonly diagnosed cancer among men worldwide.Therefore,to explore a more effective treatment strategies for prostate cancer becomes a hotspot of prostate cancer.It is well established that the tumor microenvironment plays a critical role in the malignant progression and metastasis of PCa.In the tumor microenvironment,infiltrating macrophages called tumor-associated macrophages(TAMs),are most abundant and play a dual role in tumor progression:M1-like promote anti-tumor immunity;M2-like or alternatively activated macrophages promote tumor progression.However,little is known with respect to how macrophages are recruited to the PCa microenvironment and differentiate into a M2 phenotype,and the underlying mechanism in controlling polarization of macrophages to a M1 or M2 phenotype remains unclear.PKCζ is a key regulator of cellular processes operating in cancer,and the different functions of PKCζ correlate with its tissue specificity and intracellular distribution.PKCζ plays a critical role in inhibition of prostate tumorigenesis.However,the role of cancer-derived PKCζ on the conditioning of inflammatory cells in the tumor microenvironment is still unknown.Therefore,we tested if PKCζexpression in PCa produced an effect on TAMs infiltration or polarization to restrain tumor progression and metastasis.Contents and methods1.The role of PCa-derived PKCζ on the recruitment and M2 polarization of macrophages in the prostate cancer microenvironmentImmunohistochemistry was performed to analyze the expression of PKCζ and the number of CD206+ M2 macrophages in human prostate tissue.Macrophage chemotaxis and polarization were examined respectively by transwell migration assays and a co-culture system.Quantitative real-time PCR and western blotting were used to detect M2 markers,PKCζ expression.2.The molecular mechanism of PCa-derived PKCζ controls the recruitment and M2 polarization of macrophages in the prostate cancer microenvironmentQuantitative real-time PCR,western blotting and ELISA assays were used to detect M2 markers,PKCζ,IL-4 and IL-10 expression.Neutralizing antibodies against IL-4 and IL-10 in our co-culture system were used.Results1.PKCζ in prostate cancer cells represses the recruitment and M2 polarization of macrophages in the prostate cancer microenvironmentThe expression of PKCζ increased in prostate cancer tissues,especially in the early stage,which was negatively associated with tumor grade and the number of CD206+ macrophages(P<0.001).Inhibition of PKCζ expression in PCa cells induced chemotaxis of peripheral macrophages and acquisition of M2 phenotypic features(P<0.05).2.PKCζ inhibits the M2 phenotype by regulates the secretion of IL-4 and IL-10 in prostate cancer cellsCytokines related to macrophage chemotaxis and M2 polarization were detected by RT-QPCR.IL-4 and IL-10 expression were increased by PKCζ silencing(P<0.05).The enhancement of M2 marker expression by PKCζ silencing was abolished in the presence of neutralizing antibodies against IL-4 and IL-10 in our co-culture system(P<0.01).Conclusion1.PKCζ in prostate cancer cells represses the recruitment and M2 polarization of macrophages in the prostate cancer microenvironment.2.PKCζ inhibits the M2 phenotype by regulates the secretion of IL-4 and IL-10 in prostate cancer cells.