Areca nut extract treatment elicits the fibroblastoid morphological changes, actin re-organization and signaling activation in oral keratinocytes

Background: Areca (named as betel) is an important etiological factor linked with the high prevalence of oral squamous cell carcinoma (OSCC) in South-Asian countries. This in vitro study investigated the cellular changes and signaling activation in oral keratinocytes in response to areca nut extract (ANE) treatment. Methods: Normal human oral keratinocyte (NHOK) and oral epidermoid carcinoma cell, Meng-1 (OECM-1) OSCC cell line were treated with variable dosages of ripen ANE. The morphological and cytoskeletal changes, as well as the activation of GTPase proteins and signaling kinases, were analyzed. Results: Most NHOK cells in culture were polygonal, with only <5% cells exhibiting fibroblastoid morphology. However, 10 mug/ml ANE elicited fibroblastoid morphological change, genesis of lamellipodia, loss of subcortical actin, and stress-fiber formation in approximately 25% cultivated NHOK cells. Similar morphological changes were observed in nearly all OECM-1 cells following the ANE treatment. The activation of Rac and Rho GTPase, together with the prominent phosphorylation of a stress-activated kinases, particularly JNK1, was identified in treated OECM-1 cells. Conclusion: The novel evidences from the study that ANE impairs the actin organization and activates the signals in oral keratinocytes might bestow further insight into the impacts of ANE in oral pathogenesis.