Matrix metalloproteinase-26 is present more frequently in squamous cell carcinomas of immunosuppressed compared with immunocompetent patients

Background: Skin cancers are the most frequent malignancies in organ transplant recipients (OTRs). Squamous cell carcinomas (SCCs) occur 65–250 times more frequently in OTRs and tend to be aggressive in behavior. Because matrix metalloproteinases (MMPs) have a central role in tumorigenesis and invasion, we investigated the epithelial and stromal MMP and tissue inhibitor of MMP (TIMP) expression profile in SCCs of immunosuppressed (IS) compared with immunocompetent (IC) patients to determine if differences could explain the more aggressive behavior of SCCs in OTRs. Methods: Matched pairs from 20 SCCs of IS and IC patients were studied using immunohistochemistry for MMP-1, MMP-7, MMP-8, MMP-9, MMP-13 and MMP-26 and TIMP-1 and TIMP-3. Results: Among all MMPs studied, only staining for MMP-26 was significantly more intense in cancer cells of the post-transplant group compared with the IC group (p = 0.01), whereas MMP-9 expression was more abundant in stromal macrophages surrounding SCCs of IC patients (p = 0.02). MMP-26 expression in cancer cells (p = 0.04) and that of MMP-9 in neutrophils (p = 0.005) were more abundant in SCCs of patients using cyclosporine. Conclusions: We conclude that MMP-26 and MMP-9 may contribute to the more aggressive behavior of SCCs in OTRs.