ROCK1 and ROCK2 Are Down-regulated in Aggressive and Advanced Skin Melanomas – A Clinicopathological Perspective

BACKGROUND: RhoA and its downstream effectors Rho-associated coiled-coil kinases (ROCK) 1 and 2 are central controllers of cytoskeleton dynamics, and therefore influence cell shape, adhesion and migration. Since modulation of these processes holds promise for an effective anticancer strategy, effects of ROCK inhibition have been evaluated in a number of malignancies. MATERIALS AND METHODS: Using immunohistochemistry, ROCK1 and ROCK2 expression was semi-quantitatively assessed in 129 patient-derived primary melanomas. RESULTS: There was a striking predilection for low melanocytic expression of both kinases in thick, ulcerated and mitogenic tumors, as well as in nodular histological type. ROCK1 and -2 expression in tumor-infiltrating lymphocytes (TILs) was preferentially down-regulated in advanced and aggressive tumors. Moreover, diminished ROCK2 reactivity in melanoma cells and TILs was associated with shorter melanoma-specific and recurrence-free survival. CONCLUSION: This is the first analysis of ROCK1 and -2 protein expression in clinical melanoma samples and the results indicated the suppression of ROCK signaling in melanocytes of aggressive and late-stage tumors. Functional models that more accurately represent the clinical setting are necessary to dissect the role of ROCK1 and -2 in melanoma. Additionally, our study indicates that ROCK activity in TILs may be involved in the pathogenesis of cancer, and thus merits further investigations.