Loss of Speckle-Type POZ Protein Promotes Prostate Cancer Cell Migration and Invasion Through Upregulation of MCP-1

BACKGROUND The goal of this study is to verify that the loss of speckle-type POZ protein (SPOP) promotes the migration and invasion of prostate cancer cells, and that this process is brought about by an increase in MCP-1. MATERIAL AND METHODS SPOP knockout C4-2 cells (C4-2 SPOP-/-) were verified by western blotting. Transwell and wound-healing assays were applied to verify different migration and invasion abilities between the C4-2 SPOP-/- and control cells. We used an antibody array to find different soluble chemokine factors in the C4-2 SPOP-/- cells. ELISA and qRT-PCR were applied for confirmation. To test MCP-1 function in conditioned medium, a transwell assay was applied with or without anti-MCP-1 antibody. RESULTS The western blot showed that SPOP was knocked out in sgSPOP-1 and sgSPOP-2 (different clones of C4-2 SPOP-/-). The transwell and wound-healing assays indicated that, compared with control cells, sgSPOP-1 and sgSPOP-2 had stronger migration and invasion abilities. The antibody array found that the expression of MCP-1 was upregulated in sgSPOP-1 and sgSPOP-2 conditioned medium. This result was verified by ELISA and qRT-PCR. In the prostate cancer cells, migration and invasion activity was greatly increased in C4-2 SPOP-/- conditioned medium, while this activity was decreased after anti-MCP-1 antibody neutralization. CONCLUSIONS Our findings suggest that the loss of SPOP in C4-2 cells promotes increased cell migration and invasion abilities. This may be realized by upregulating the expression of MCP-1. The inhibition of MCP-1 expression may be an effective treatment for SPOP-mutant prostate cancer.