Matrix metallopeptidase 2 (MMP2) mediates MHC class I polypeptide-related sequence A (MICA) shedding in renal cell carcinoma

Abstract

Introduction: The MHC class i chain-related molecule A (MICA) is a ligand for the natural killer group 2, member D (NKG2D) immunoreceptor activation. The engagement of tumor cell surface MICA to NKG2D stimulates the NK and T cell antitumor immunity. Shedding of MICA by tumor cells facilitates tumor immune evasion, which might partially contribute to tumor progression.

Material and methods: Inmunohistochemistry was performed on both normal and neoplastic renal tissue. Human renal carcinoma cell lines 786-0 and ACHIN were transfected and target sequences to silence human MMP2 by shRNA expression were established. The degree of MICA shedding was measured and quantitative real-time PCR and Western-blot analysis were performed.

Results: The membrane type matrix metalloproteinase 2 (MMP2) mediated the MICA shedding, which was blocked by suppression of MMP2 expression. Concomitantly, MMP2 over-expression enhanced the MICA shedding, indicating that MMP2 was involved in the renal cell carcinoma-associated proteolytic release of soluble MICA (sMICA), which facilitated the tumor immune escape.

Conclusions: These findings suggested that MMP2 might be a new potential target for tumor immune therapy. Elucidation of the mechanisms by which tumors shed MICA could be of a great importance for cancer treatment in order to reinforce the NK and T cell antitumor immunity.

Keywords: Carcinoma de células renales; MICA; MMP2; NKG2D; Renal cell carcinoma.