A preliminary immunohistochemical study of signal transducer and activator of transcription (STAT) proteins in primary oral malignant melanoma

Publication date: Available online 3 November 2017
Source:Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology
Author(s): Nikolaos G. Nikitakis, Ioannis Gkouveris, Erofili Papadopoulou, Argyrios Daskalopoulos, Alexandra Sklavounou
ObjectivePrimary oral malignant melanoma (POMM) is a rare type of malignancy with a very poor prognosis, the molecular pathogenesis of which remains elusive. The aim of this study was to assess the expression status of signal transducers and activators of transcription (STAT) proteins in POMM.Study DesignSix POMMs were included in the study. Total protein levels of STAT1, 3 and 5a, as well as the tyrosine phosphorylated (activated) form of STAT3 (pSTAT3), were assessed immunohistochemically.ResultsImmunohistochemical evaluation of total STAT3 revealed diffuse and strong cytoplasmic and nuclear expression in the majority of tumor cells of all cases, while activated pSTAT3 showed mostly mild nuclear expression in 5-40% of malignant melanocytes in all cases. Evaluation of STAT1 and STAT5a showed mainly mild cytoplasmic expression in the absence of nuclear localization.ConclusionThe demonstration of aberrant STAT3 expression and activation in oral malignant melanocytes supports a possible role of this molecule in POMM. In contrast, STAT5a shows only limited cytoplasmic expression mitigating against its involvement in POMM. Also, STAT1 low levels may have implications for POMM sensitivity to interferon (IFN)-based therapeutic strategies, considering the role of this molecule in cutaneous melanoma immunotherapy.



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