Cell-secreted enzymes, such as matrix metalloproteinases (MMPs), are important for many different types of cellular processes including angiogenesis, tissue repair, and metastasis. Understanding the functional impact of changes in MMP activity during cancer treatment is an important facet that is not always evaluated as part of preclinical research. With MMP activity being a critical component of the metastatic cascade, we designed a 3D hydrogel system to probe whether pharmacological inhibition affected human melanoma cell proteolytic activity. Metastatic melanoma, in particular, is a highly aggressive and drug resistant form of skin cancer; the 5-year survival rate is approximately 15% and patients, on average, relapse within 6 months. The relationship between MMP activity and drug treatment is unknown but may be an important cellular response to assess. Therefore, we utilized an <i>in situ </i>fluorogenic MMP sensor peptide in order to determine how drug treatment may affect or influence melanoma cells’ MMP activity in 3D. Using this MMP sensor peptide, we encapsulated melanoma cells from varying stages of progression within PEG-based hydrogels to examine the relationship between drug treatment and MMP activity. From these results, a metastatic melanoma cell line (A375) and two inhibitors that inhibit the RAF protein (PLX4032 and sorafenib) were studied further to determine whether the changes in MMP activity led to a functional change in cell behavior. The A375 cells exhibited an increase in MMP activity despite an overall decrease in metabolic activity with PLX4032 treatment. The changes in proteolytic activity correlated with an increase in elongated cell morphology and increased single cell migration. In contrast, sorafenib did not change MMP activity or cell motility, showing that the changes induced by PLX4032 were not a universal response to small molecule inhibition. Therefore, we argue the importance of studying MMP activity with drug treatment and its possible implications for unwanted side effects. Ongoing work addresses the influence of dimensionality of culture conditions on melanoma drug responsiveness and whether or not a 3D environment may confer more drug resistant behavior compared to a soft 2D substrate.

Multifunctional hydrogel assays for 3D culture of melanoma cells reveal increased matrix metalloproteinase activity and migration in response to BRAF/MEK inhibitors

249th National Meeting (2015)

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