Integrin ανβ6 Protein Expression and Prognosis in Solid Tumors: A Meta-Analysis.

Abstract

Integrins are a family of adhesion receptor proteins that provide signaling from the extracellular matrix to the cytoplasm. They have been associated with cancer by promoting migration, invasion, metastasis, and survival. ανβ6 integrin is upregulated in several tumors. Here, we evaluate the prognostic impact of ανβ6 integrin protein expression in solid tumors. A systematic search of electronic databases identified publications exploring the effect of ανβ6 integrin on overall survival (OS). Hazard ratios (HRs) were pooled in a meta-analysis using generic inverse variance and random effects modeling. Subgroup analyses were conducted based on tumor site, tumor stage, antibody used for immunohistochemistry (IHC) and method for extraction of the HR. A meta-regression explored the influence of clinical variables on the magnitude of effect of ανβ6 integrins on OS. Seventeen studies comprising 5795 patients met the inclusion criteria. High ανβ6 integrin expression in tumors was associated with worse OS (HR 1.65, 95% confidence interval [CI] 1.32-2.06; Cochran'sQ p < 0.001, I2 = 81%). Adverse outcomes were similar in all tumor sites (subgroup difference p = 0.10), with the strongest association between ανβ6 integrins and OS in gastric cancer (HR 2.20, 95% CI 1.71-2.83) and the lowest in head and neck cancer (HR 1.21, 95% CI 0.79-1.83). There was no significant difference between early-stage and metastatic cancer, type of IHC antibodies, and analysis methods. High expression of ανβ6 integrins is associated with adverse survival outcome in several tumors. Prospective studies evaluating the prognostic impact of ανβ6 integrin and its role as a therapeutic target are warranted.