The extracellular matrix (ECM) plays critical roles in tumor progression and metastasis. However, the contribution of ECM proteins to early metastatic onset in the peritoneal cavity remains unexplored. Here, we suggest a new route of metastasis through the interaction of integrin alpha 2 (ITGA2) with collagens enriched in the tumor coinciding with poor outcome in patients with ovarian cancer. Using multiple gene-edited cell lines and patient-derived samples, we demonstrate that ITGA2 triggers cancer cell adhesion to collagen, promotes cell migration, anoikis resistance, mesothelial clearance, and peritoneal metastasis in vitro and in vivo. Mechanistically, phosphoproteomics identify an ITGA2-dependent phosphorylation of focal adhesion kinase and mitogen-activated protein kinase pathway leading to enhanced oncogenic properties. Consequently, specific inhibition of ITGA2-mediated cancer cell-collagen interaction or targeting focal adhesion signaling may present an opportunity for therapeutic intervention of metastatic spread in ovarian cancer.

Polydopamine can form biocompatible particles that convert light into heat. Recently, a protocol has been optimized to synthesize polydopamine/protein hybrid nanoparticles that retain the biological function of proteins, and combine it with the stimuli-induced heat generation of polydopamine. We have utilized this novel system to form polydopamine particles, containing transferrin (PDA/Tf). Mouse melanoma cells, which strongly express the transferrin receptor, were exposed to PDA/Tf nanoparticles (NPs) and, subsequently, were irradiated with a UV laser. The cell death rate was monitored in real-time. When irradiated, the melanoma cells exposed to PDA/Tf NPs underwent apoptosis, faster than the control cells, pointing towards the ability of PDA/Tf to mediate UV-light-induced cell death. The system was also validated in an organotypic, 3D-printed tumor spheroid model, comprising mouse melanoma cells, and the exposure and subsequent irradiation with UV-light, yielded similar results to the 2D cell culture. The process of apoptosis was found to be targeted and mediated by the lysosomal membrane permeabilization. Therefore, the herein presented polydopamine/protein NPs constitute a versatile and stable system for cancer cell-targeting and photothermal apoptosis induction.

Summary Integrin alpha 2 (ITGA2) promotes cancer metastasis through selective adhesion to ECM proteins; however, the specific contribution of integrin glycosylation remains uncertain. We provide evidence that ITGA2 is a highly glycosylated transmembrane protein expressed in ovarian cancer tissue and cell lines. In-depth glycoproteomics identified predominant N - and O -glycosylation sites harboring substantially divergent ITGA2 glycosylation profiles. Generated putative ITGA2 N -glycosite mutants halted collagen and laminin binding and cells lacking N -glycosylated ITGA2 were marginally adherent to collagen, likely associated with its enhanced proteasome degradation through poly-ubiquitination. Proteomic and enrichment pathway analysis revealed increased cellular apoptosis and collagen organization in non-glycosylated ITGA2 mutant cells. Moreover, we provide evidence that ITGA2-specific sialylation is involved in selective cell-ECM binding. These results highlight the importance of glycans in regulating ITGA2 stability and ligand binding capacity which in turn modulates downstream focal adhesion and promotes cell survival in a collagen environment.