Potential biological process of X-linked inhibitor of apoptosis protein in renal cell carcinoma based upon differential protein expression analysis

Isobaric tags for relative and absolute quantitation-based quantitative proteomic analysis of X-linked inhibitor of apoptosis and H2AX in etoposide-induced renal cell carcinoma apoptosis

Background:

X-linked inhibitor of apoptosis (XIAP) is a vital factor in the anti-apoptosis mechanism of tumors and is highly expressed in renal cell carcinoma (RCC). However, the mechanism through which XIAP regulates DNA damage repair is unknown. This study investigated the regulatory mechanism of XIAP in etoposide-induced apoptosis in two Caki-1 cell lines with high or low XIAP expression.

Methods:

The two cell lines were established using RNA interference technology. The differentially expressed proteins in the two cell lines were globally analyzed through an isobaric tags for relative and absolute quantitation-based quantitative proteomics approach. Proteomic analysis revealed 255, 375, 362, and 5 differentially expressed proteins after 0, 0.5, 3, and 12 h of drug stimulation, respectively, between the two cell lines. The identified differentially expressed proteins were involved in numerous biological processes. In addition, the expression of histone proteins (H1.4, H2AX, H3.1, H3.2, and H3.3) was drastically altered, and the effects of XIAP silencing were accompanied by the marked downregulation of H2AX. Protein-protein interactions were assessed and confirmed through immunofluorescence and Western blot analyses.

Results:

The results suggested that XIAP may act as a vital cell signal regulator that regulates the expression of DNA repair-related proteins, such as H2AX, and influences the DNA repair process.

Conclusions:

Given these functions, XIAP may be the decisive factor in determining the sensitivity of RCC cell apoptosis induction in response to chemotherapeutic agents.

Prognostic significance of X-linked inhibitor of apoptosis protein in patients with gastrointestinal tract cancers: A meta-analysis

BACKGROUND

The aim of this meta-analysis was to systematically evaluate the prognostic significance of X-linked inhibitor of apoptosis protein (XIAP) in patients with gastrointestinal tract (GIT) cancers.

METHODS

PubMed, Web of Science, EMBASE, Cochrane Library and China National Knowledge Infrastructure were searched for potentially eligible literature. The baseline characteristics and relevant data were extracted. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated to assess the prognostic role of XIAP in patients with GIT cancers.

RESULTS

Twelve studies with 2,477 patients were included. The pooled HRs of higher expression of XIAP for overall survival (OS) and recurrence free survival (RFS) in patients with GIT cancers were 1.64 (95% CI, 1.27-2.13) and 1.06 (95% CI, 0.96-1.16), respectively. Subgroup analysis and sensitivity analysis were also performed. No significant publication bias was found.

CONCLUSION

Our results suggested that XIAP could be a prognostic marker for OS but not RFS in patients with GIT cancers. Higher expression of XIAP was related to poorer OS. These findings may help evaluate the prognosis of patients and assist future research on novel therapeutic strategies of GIT cancers by targeting XIAP. However, more well-designed studies are warranted to verify the results.