PDZ and LIM domain protein 4 suppresses the growth and invasion of ovarian cancer cells via inactivation of STAT3 signaling

Aims: PDZ and LIM domain protein 4 (PDLIM4) is frequently repressed in cancer tissues. However, the expression and role of PDLIM4 in ovarian cancer has not been addressed. Main methods: In this study, we examined the expression and prognostic significance of PDLIM4 in ovarian cancer. The function of PDLIM4 in ovarian cancer cell growth, invasion, and tumorigenesis was further explored. Key findings: PDLIM4 is downregulated in ovarian cancer compared to adjacent normal ovarian tissues. Downregulation of PDLIM4 is correlated with advanced tumor stage and lymph node metastasis. Low PDLIM4 expression is significantly associated with shorter overall survival in patients with ovarian cancer (P = 0.0136). Biologically, PDLIM4 overexpression suppresses the proliferation, colony formation, migration, and invasion of both CAOV3 and SKOV3 ovarian cancer cells, compared to empty vector-transfected cells. Consistently, in vivo data show that PDLIM4 overexpression inhibits the growth of SKOV3 xenograft tumors. Mechanistic investigation reveals that overexpression of PDLIM4 blocks the phosphorylation of STAT3 and represses STAT3-dependent transcriptional activation. Moreover, ectopic expression of PDLIM4 downregulates the expression of CCND1 and MMP9 in ovarian cancer cells. Rescue experiments demonstrate that overexpression of constitutively active STAT3 reverses PDLIM4-induced anticancer effects on ovarian cancer cells. Significance: Overall, PDLIM4 downregulation is associated with aggressive tumor features and poor prognosis in ovarian cancer patients. PDLIM4 suppresses ovarian cancer cell growth and invasion by inhibiting STAT3 signaling. This study provides a potential therapeutic target for ovarian cancer.