An “in vitro”study on lung cells exposed to fluoro-edenite fibres. Biological role of retinoblastoma proteins

Introduction: In this study we addressed the expression of Rb and pRb protein in human lung epithelial A549 and MeT-5A cell cultures treated with three concentrations of fluoro-edenite fibres to gain insights into the biomolecular mechanisms underlying the interaction between these environmental particulates/fibres and human respiratory epithelium. Several asbestos-like mineral fibres, including fluoro-edenite, may cause lung cancer and/or other lung diseases. However, biological and molecular mechanisms linked to cancer development after mineral fibres exposure were not fully investigated.Methods: In the present study, mesothelial (MeT-5A) and human bronchoalveolar alveolar epithelial (A549) cell lines were incubated with rising concentrations of fluoro-edenite to evaluate the expression of retinoblastoma (Rb) protein, which has been demonstrated to play an important role in cell cycle control and tumour progression. Results: Intriguingly, these results show that Rb expression was unchanged, while the level of the phosphorylated protein increased significantly in a dose-dependent manner, suggesting an involvement of this regulator protein in the pathogenesis of the lung diseases induced by mineral fibres. Conclusion: In conclusion, fluoro-edenite regulates the expression of pRb to trigger a network of signals strictly connected with cell proliferation and neoplastic cell transformation.