Characterization of mechano-microenvironment of acral melanoma and its potential impact on tumor cell invasion.

Abstract

e21062 Background: Acral melanoma is the main subtype in Asia, and tends to be insensitive to conventional and novel therapies compared with cutaneous melanomas. It has been proved that biomechanical alterations inside the tumor microenvironment significantly affect tumor progression in breast, pancreatic and other cancers(Hepatology. 2016 July ; 64(1): 261–275; Cold Spring Harbor Symposia on Quantitative Biology, Volume LXXXI) . Hence, we hypothesized that the biomechanical microenvironment plays critical roles in proliferation and invasion in acral melanoma. In this study, the main purpose is to observe whether melanoma cells have the same ability called “durotaxis” as other tumors, which to respond to a gradient of extracellular stiffness and migrate in a directed fashion. Methods: In this study, the stiffness was compared between the acral melanoma tissue and the normal tissue by using the atomic force microscope (AFM) with fresh samples and the freezing microtome sectioning specimen (J. Matthew Barnes et al., Nature Cell Biology 2018.) . A stiffness gradient polyacrylamide hydrogel system was constructed to observe how the acral melanoma cells response. Using automated tracking (Curr Protoc Cell Biol. ; 76: 12.12.1–12.12.16.) of positional data for large sample size of single migrating cells to systematically analyze polarized melanoma cell migration in response to stiffness gradient. Results: The results showed that 1) all the acral melanoma cell lines tested displayed strong anti-durotactic migratory response, which was in accordance with the AFM measurement that the melanoma microenvironment gradually softened; 2) Acral melanoma cells tend to move toward softer areas on gradient gels, which is contrary to the migration behavior of most other tumor cells. Conclusions: In this study, we presented the different migratory pattern of acral melanoma cells. It may illustrate the invasion mechanism for aral melanoma cells. It could also herald that extracellular matrix may be a potential therapeutic target in acral melanomas.