Role of Tip60 in human melanoma cell migration, metastasis, and patient survival.

The tumor suppressor Tip60 regulates gene transcription, DNA damage response, apoptosis, and cancer development, but its role in melanoma is unknown. In this study, we investigated the expression pattern of Tip60 in melanoma and assessed its prognostic value. Using tissue microarrays consisting of 448 cases of melanomas (201 for the training set and 247 for the validation set) and 105 cases of nevi, we found that Tip60 expression was significantly reduced in metastatic melanoma compared to common nevi (P=0.045), dysplastic nevi (P=0.047), and primary melanoma (P=0.001). Kaplan-Meier survival curve and univariate Cox regression analyses showed that reduced Tip60 expression was associated with a poorer 5-year disease-specific survival in primary melanoma (P=0.016) and metastatic melanoma patients (P=0.027). Multivariate Cox regression analyses indicated that Tip60 expression was an independent prognostic marker for primary (P=0.024) and metastatic melanomas (P=0.035). In vitro wound healing assay showed that enforced Tip60 expression inhibited but Tip60 knockdown enhanced melanoma cell migration, suggesting that Tip60 might regulate melanoma metastasis. Finally, we showed that overexpression of Tip60 in melanoma cells resulted in significantly increased chemosensitivity. Our data indicate that Tip60 may serve as a potential biomarker for melanoma patient outcome as well as a potential therapeutic target.