Introduction: Lung cancer is the result of a multistep accumulation of genetic and/or epigenetic alterations; therefore, a better understanding of the molecular mechanism by which these alterations affect lung cancer pathogenesis would provide new diagnostic procedures and prognostic factors for early detection of recurrence. The remarkable qualitative and quantitative modifications of extracellular matrix components as the deubiquitinating enzyme (USP17), hyaluronan (HA), and hyaluronan synthases 2 (HAS 2) may favor invasion, cellular motility, and proliferation in several cancers including lung.

Results: The silencing of USP17 led to decreased hyaluronan production, whereas the suppression of USP4 increased hyaluronan synthesis. Importantly, high levels of USP17 and HAS2 were detected in a panel of cancer cell lines compared to normal cells, and immunohistochemical stainings revealed higher expression of USP17 and HAS2 in tissues of lung cancer patients compared to normal tissue. Numerous epithelial cells expressed USP17 and HAS2 in dysplasia compared to squamous cell carcinoma (SqCC) (p=0.001). USP17 and HAS2 were prominently expressed in adenocarcinoma (ADC) (p≤0.005). HA immunostaining indexes were increased in ADC and SqCC compared to normal and dysplasia cells (p=0.05). Consistent with the immunohistochemical analyses, low amounts of hyaluronan and USP17 were observed in SqCC by confocal analysis, coincident with less colocalization as determined by confocal microscopy. In contrast, a high expression of hyaluronan (48% of positive index) and high USP17 expression (78% of positive index) in ADC was consistent with a higher degree of colocalization.

Conclusions: HAS2, hyaluronan and USP17 were expressed at higher levels in particular in preneoplastic lesions and ADC, suggesting a role in NSCLC oncogenic transformation, possibly by promoting cellular division by USP17-mediated. Elucidation of the mechanism of how USP17 and HAS2 cooperate in the regulation of the cell cycle might be of therapeutic importance.