Invadopodia proteins, cortactin, N-WASP and WIP differentially promote local invasiveness in ameloblastoma.

BACKGROUND: Cell migration and invasion through interstitial tissues are dependent upon several specialized characteristics of the migratory cell notably generation of proteolytic membranous protrusions or invadopodia. Ameloblastoma is a benign odontogenic epithelial neoplasm with a locally infiltrative behaviour. Cortactin and MMT1-MMP are two invadopodia proteins implicated in its local invasiveness. Other invadopodia regulators, namely N-WASP, WIP and Src kinase remain unclarified. This study addresses their roles in ameloblastoma. MATERIALS AND METHOD: Eighty-seven paraffin-embedded ameloblastoma cases (20 unicystic, 47 solid/multicystic, 3 desmoplastic and 17 recurrent) were subjected to immunohistochemistry for expression of cortactin, N-WASP, WIP, Src kinase and F-actin, and findings correlated with clinicopathological parameters. RESULTS: Invadopodia proteins (except Src kinase) and F-actin were widely detected in ameloblastoma (cortactin: n = 73/87, 83.9%; N-WASP: n = 59/87; 67.8%; WIP: n = 77/87; 88.5%; and F-actin: n = 87/87, 100%). Protein localization was mainly cytoplasmic and/or membranous, and occasionally nuclear for F-actin. Cortactin, which functions as an actin-scaffolding protein, demonstrated significantly higher expression levels within ameloblastoma tumoral epithelium than in stroma (P < 0.05). N-WASP, which coordinates actin polymerization and invadopodia-mediated extracellular matrix degradation, was overexpressed in the solid/multicystic subtype (P < 0.05). WIP, an upstream regulator of N-WASP, and F-actin were significantly upregulated along the tumour invasive front compared to tumour centres (P < 0.05). Except for males with cortactin overexpression, other clinical parameters (age, ethnicity and anatomical site) showed no significant correlations. CONCLUSIONS: Present results suggest that local invasiveness of ameloblastoma is dependent upon the migratory potential of its tumour cells as defined by their distribution of cortactin, N-WASP and WIP in correlation with F-actin cytoskeletal dynamics.

Decreased expression of profilin 2 in oral squamous cell carcinoma and its clinicopathological implications.

Profilins are small proteins essential for many normal cellular dynamics and constitute one of the crucial components of actin-based cellular motility. Several recent studies have implicated a role for the profilin (PFN) family in cancer pathogenesis and progression. However, their expression and promising functions are largely unknown in oral squamous cell carcinoma (OSCC). In this study, we analyzed the correlation between PFN1 and PFN2 expression in vitro and in vivo. The protein expression levels were roughly compared between cell lines (HIOEC, HB96) with the employment of mass spectrometry. PFN2 was singled out as one of the significantly down-regulated genes in the cancerous HB96 cells. The expression levels of PFN1 and PFN2 in vitro were validated by RT-PCR, real-time PCR and Western blotting. Laser scanning confocal microscopy was used for the first time to assess the localization of PFN2 expression. In subsequent experiments, we observed the relationship between PFN2 expression levels and the proliferation of transfected HB96 cancer cells. VASP, N-WASP and P27 expression was also examined in the PFN2-transfected or non-transfected HB96 cells. In vivo, antigen expression was determined by immunohistochemical analyses in 88 paired tissue specimens. Decreased protein expression was confirmed in cancerous tissues from 88 OSCC patients compared with paracancerous normal mucous epithelia. Tumors with weak PFN2 expression were associated with a significantly worse prognosis than strongly expressed tumours (P<0.001). Other statistical analyses were performed to assess the differences in expression and their clinical and pathological significance. In conclusion, PFN2 can be utilized as both a potential suppressor marker and a prognostic protein for OSCC. The function of PFN2 may be to regulate the N-WASP/Arp2/3 signaling pathway.