Abstract A109: Matrix metalloproteinase-2 stimulates Toll-like receptor-2 on melanoma cells to induce immunosuppressive inflammation in the tumor microenvironment

Extracellular proteinases, such as matrix metalloproteinases (MMPs), support tumor progression through modulation of the tumor microenvironment (TME). MMP-2, in particular, is overexpressed in several cancers and high MMP-2 levels are associated with advanced tumor stages, increased dissemination and poorer survival/prognosis. Our lab has previously demonstrated that upon antigenic stimulation, MMP-2-specific CD4+ T-cells, derived from patients with melanoma, secrete inflammatory TH2 cytokines. We subsequently showed that active MMP-2 drives the differentiation of TH2 responses by inhibiting IL-12 production and up-regulating OX40L expression on dendritic cells (DCs). We published our novel discovery identifying MMP-2 as a ligand for TLR-2 and showed that MMP-2 mediated TLR-2 stimulation lead to up-regulation OX40L on DCs (Cell Reports 2014). This is particularly interesting as TLR-2 stimulating adjuvants are being tested for immunotherapy. However, the full spectrum of how TLR-2 activation affects tumor cells or immune cells remains unclear.The main purpose of this study is to characterize the role of TLR-2-MMP-2 axis in shaping the TME through its influence on tumor cells and tumor infiltrating immune cells. Towards this end we performed RNA sequencing to identify genes induced in human DCs upon MMP-2 stimulation. One of these targets is an atypical member of the canonical NFκB family, IkappaBzeta (NFKBIZ or IκBζ). We show that MMP-2 secreted by melanoma cells upregulates IκBζ in DCs through TLR-2 and promotes secretion of Th2 and Th17 inducing cytokines. Furthermore, we screened several human melanoma cell lines for high and low MMP-2 and TLR-2 expression. CRISPR/Cas9 technology was used to stably knock out TLR-2, TLR-4 and MMP-2 in tumor cell lines. Early data indicates a role for tumor cell intrinsic MMP-2 in promoting secretion of protumorigenic cytokines and chemokines from tumor cells that support immune evasion and tumor growth, both constitutively and upon TLR-2 stimulation. Moreover, IκBζ was found to positively regulate MMP-2 dependent protumorigenic inflammation. In summary, we have identified a novel role for MMP-2 as a TLR-2 alarmin with particular emphasis on induction of atypical signaling modulator IκBζ and have uncovered a new role for MMP-2 in modulating tumor cell-induced inflammation. Taken together, our previous research and current data indicate that MMP-2 acts simultaneously as an endogenous T-cell differentiation "conditioner" and a tumor-associated antigen. Therefore, delving into MMP-2 signaling mechanisms in the TME holds a strong potential for discovering novel therapeutic options for treating melanoma. Citation Format: Mansi Saxena, Keerthi Caroline Sadanala, Luciana Rebiero Muniz-Bongers, Nina Bhardwaj. Matrix metalloproteinase-2 stimulates Toll-like receptor-2 on melanoma cells to induce immunosuppressive inflammation in the tumor microenvironment [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A109.