Targeting Extracellular Matrix Remodeling Restores BRAF Inhibitor Sensitivity in BRAFi-resistant Melanoma

Abstract

Purpose: The extracellular matrix (ECM) is an intriguing, yet understudied component of therapy resistance. Here, we investigated the role of ECM remodeling by the collagenase, MT1-MMP, in conferring resistance of v-Raf murine sarcoma viral oncogene homolog B1 (BRAF)-mutant melanoma to BRAF inhibitor (BRAFi) therapy. Experimental Design: Publicly available RNA-sequencing data and reverse phase protein array were used to determine the relevance of MT1-MMP upregulation in BRAFi-resistant melanoma in patients, patient-derived xenografts, and cell line–derived tumors. Short hairpin RNA (shRNA)-mediated knockdown of MT1-MMP, inhibition via the selective MT1-MMP/MMP2 inhibitor, ND322, or overexpression of MT1-MMP was used to assess the role of MT1-MMP in mediating resistance to BRAFi. Results: MT1-MMP was consistently upregulated in posttreatment tumor samples derived from patients upon disease progression and in melanoma xenografts and cell lines that acquired resistance to BRAFi. shRNA- or ND322-mediated inhibition of MT1-MMP synergized with BRAFi leading to resensitization of resistant cells and tumors to BRAFi. The resistant phenotype depends on the ability of cells to cleave the ECM. Resistant cells seeded in MT1-MMP uncleavable matrixes were resensitized to BRAFi similarly to MT1-MMP inhibition. This is due to the inability of cells to activate integrinβ1 (ITGB1)/FAK signaling, as restoration of ITGB1 activity is sufficient to maintain resistance to BRAFi in the context of MT1-MMP inhibition. Finally, the increase in MT1-MMP in BRAFi-resistant cells is TGFβ dependent, as inhibition of TGFβ receptors I/II dampens MT1-MMP overexpression and restores sensitivity to BRAF inhibition. Conclusions: BRAF inhibition results in a selective pressure toward higher expression of MT1-MMP. MT1-MMP is pivotal to an ECM-based signaling pathway that confers resistance to BRAFi therapy.

MT1-MMP-dependent ECM processing regulates laminB1 stability and mediates replication fork restart

“…Cell suspension of 10 6 cells per 100 μL was combined with 400 μL of HEPES with qGEL Lyophilized Powder (formulation IDs: NSC4QA432R and NSC4EN562R [ 8 , 23 ], qGel Bio). The mixture was incubated at 37°C, 5% CO 2 for 30 minutes until a solid matrix was formed with cells embedded inside.…”

Cytoskeletal Remodelling as an Achilles’ Heel for Therapy Resistance in Melanoma

“…The membrane-tethered MT1-MMP was upregulated through TGF-β in BRAFi-resistant melanomas [117]. MT1-MMP1 remodelled the ECM and activated β1-integrin-FAK signalling to sustain survival under the MAPK blockade.…”

Neurofibromin Deficiency and Extracellular Matrix Cooperate to Increase Transforming Potential through FAK-Dependent Signaling

“…In breast cancer models, deregulated activation of FAK promotes tumor progression and metastasis by affecting the cross-talk between cancer and stromal cells and by sensitizing tumor cells to ECM biochemical and mechano-signals, with profound effects on their genomic landscape [ 27 ]. Pharmacological inhibition of FAK enhances chemosensitivity in taxane-resistant cells [ 28 , 29 , 30 , 31 , 32 ]. In pancreatic adenocarcinoma, where desmoplastic stroma functions as a barrier to T cell infiltration and to chemotherapy, inhibition of hyperactive FAK by Defactinib (VS-6063) reduces stromal density and the immunosuppressive features of the microenvironment [ 33 , 34 , 35 ].…”