Six-transmembrane epithelial
antigen of prostate 4 (STEAP4) is involved in the development of human
cancers. However, the role of STEAP4 in
prostate cancer remains largely unknown. The purpose of this research is to explore the role and action mechanism of STEAP4 in
prostate cancer development under
lipopolysaccharide (LPS)-induced inflammatory microenvironment. STEAP4 expression was analyzed by Gene Expression Profiling Interactive Analysis (GEPIA), UALCAN and
Cancer Cell Line Encyclopedia (CCLE), and its prognostic value was analyzed by LinkedOmics. STEAP4-correlated genes were analyzed by LinkedOmics and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. STEAP4 level was detected by Western blotting or qRT-PCR. Proliferation was investigated by
CCK-8 and EdU staining. Inflammatory
cytokine levels were detected by ELISA. The cyclic
guanosine monophosphate (cGMP)-
protein kinase G (PKG) pathway was detected by ELISA and Western blotting. STEAP4 level was increased in
prostate cancer tissues, and high expression of STEAP4 was associated with the poor overall survival. LPS promoted cell viability and STEAP4 expression. STEAP4 knockdown attenuated LPS-induced
inflammation in
prostate cancer cells. STEAP4 downregulation mitigated LPS-induced
tumorigenesis by decreasing cell proliferation. STEAP4 silencing reversed LPS-induced inactivation of the cGMP-PKG pathway. Inhibition of the cGMP-PKG pathway using inhibitor
KT5823 relieved STEAP4 silencing-mediated suppression of cell proliferation and
inflammation in LPS-stimulated cells. In conclusion, STEAP4 silencing inhibits LPS-induced proliferation of
prostate cancer cells by activating the cGMP-PKG pathway.