Clinicopathological and prognostic significance of speckle-type POZ protein in cancers: a systematic review and meta-analysis

Prognostic and Predictive Role of SPOP Mutations in Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT

Mutations in the speckle-type POZ (SPOP) gene are frequently identified in prostate cancer (PC); yet, prognostic implications for affected patients remain unclear. Limited consensus exists regarding tailored treatments for SPOP-mutant (SPOPmut) PC.

OBJECTIVE

To elucidate the prognostic and predictive significance of SPOP mutations across distinct PC stages and treatments.

EVIDENCE ACQUISITION

A systematic literature search of PubMed, Embase, and Scopus was conducted up to January 29, 2024. The meta-analysis included studies comparing survival outcomes between SPOPmut and SPOP wild-type (SPOPwt) PC.

EVIDENCE SYNTHESIS

From 669 records, 26 studies (including five abstracts) were analyzed. A meta-analysis of metastasis-free survival in localized (hazard ratio [HR]: 0.72, 95% confidence interval [CI]: 0.59-0.88; p < 0.01) and overall survival (OS) in metastatic PC (HR: 0.64, 95% CI: 0.53-0.76; p < 0.01) showed a favorable prognosis for patients with SPOPmut PC. In metastatic settings, SPOP mutations correlated with improved progression-free survival (PFS) and OS in patients undergoing androgen deprivation therapy ± androgen receptor signaling inhibitor (HR: 0.51, 95% CI: 0.35-0.76, p < 0.01, and HR: 0.60, 95% CI:0.46-0.79, p < 0.01, respectively). In metastatic castration-resistant PC, only abiraterone provided improved PFS and OS to patients with SPOP mutations compared with patients with SPOPwt, but data were limited. SPOP mutations did not correlate with improved PFS (p = 0.80) or OS (p = 0.27) for docetaxel.

CONCLUSIONS

Patients with SPOPmut PC seem to exhibit superior oncological outcomes compared with patients with SPOPwt. Tailored risk stratification and treatment approaches should be explored in such patients.

PATIENT SUMMARY

Speckle-type POZ (SPOP) mutations could be a favorable prognostic factor in patients with prostate cancer (PC) and may also predict better progression-free and overall survival than treatment with hormonal agents. Therefore, less intensified treatments omitting chemotherapy for patients with SPOP-mutant PC should be explored in clinical trials.

BCLAF1 binds SPOP to stabilize PD-L1 and promotes the development and immune escape of hepatocellular carcinoma

Interaction between programmed death-1 (PD-1) ligand 1 (PD-L1) on tumor cells and PD-1 on T cells allows tumor cells to evade T cell-mediated immune surveillance. Strategies targeting PD-1/PD-L1 have shown clinical benefits in a variety of cancers. However, limited response rates in hepatocellular carcinoma (HCC) have prompted us to investigate the molecular regulation of PD-L1. Here, we identify B cell lymphoma-2-associated transcription factor 1 (BCLAF1) as a key PD-L1 regulator in HCC. Specifically, BCLAF1 interacts with SPOP, an E3 ligase that mediates the ubiquitination and degradation of PD-L1, thereby competitively inhibiting SPOP-PD-L1 interaction and subsequent ubiquitination and degradation of PD-L1. Furthermore, we determined an SPOP-binding consensus (SBC) motif mediating the BCLAF1-SPOP interaction on BCLAF1 protein and mutation of BCLAF1-SBC motif disrupts the regulation of the SPOP-PD-L1 axis. In addition, BCLAF1 expression was positively correlated with PD-L1 expression and negatively correlated with biomarkers of T cell activation, including CD3 and CD8, as well as with the level of immune cell infiltration in HCC tissues. Besides, BCLAF1 depletion leads to a significant reduction of PD-L1 expression in vitro, and this reduction of PD-L1 promoted T cell-mediated cytotoxicity. Notably, overexpression of BCLAF1 sensitized tumor cells to checkpoint therapy in an in vitro HCC cells-Jurkat cells co-culture model, whereas BCLAF1-SBC mutant decreased tumor cell sensitivity to checkpoint therapy, suggesting that BCLAF1 and its SBC motif serve as a novel therapeutic target for enhancing anti-tumor immunity in HCC.