Mechanisms of neuroendocrine differentiation of lung carcinoma cells and their cell biological siginifcances : trials from the points of proteomics analyses

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Aims of this research projects include following issues : 1. analyses alterations of mRNAs and proteins expressed in human lung cancer cell lines transfected with a lung neuroendocrine master gene, hASH1, 2. analyses cell biological effects including cell differentiation, proliferation and morphogenesis by gain or loss of the neuroendocrine genes, 3. focuses some key molecules among the molecules found by DNA miroarray and proteomics analyses ad study functions of these molecules.We have established hASH1-transfected human lung adenocarcinoma cell lines and Notch1-transfected human small cell carcinoma cell lines. HASH1 transfection induced neuroendocrine phenotypes in adenocarcinoma cells and upregulation of neuroendocrine markers such as chromogranin A, but, the tumors grown in the subcutaneous tissue of nude mice showed usual adenocarcinoma morphology even though they have neuroendocrine differentiation. On the other hand, the Notch1-transfected human small cell carcinoma cell lines … More lose neuroendocrine phenotypes, showing nuclear translocation of HES1 and loss of nuclear hASH1. Moreover, Notch1 transfection made the cuture cells, which were floating in the medium before transfection, adhere to the plastic dishes, and up-regulated expression of E-cadherin, integrins, and CD44. Moreover, we studied cross-talks between the Notch1-Hes1-hASH1 system and other cell signalling systems. Cell proliferation signals via MAP kinase and ATT/PI3kinase downregulated hASH1 and alter cell differentiation toward non-neuroendocrine. We found that small cell carcinoma cells posesse large amount of STAT3, but STAT3 was underphosphorylated though non-small cell carcinoma cells have phosphorylated STAT3. Thus, neuroednodrine differentiation is affected by various signalling systems. We recently established Flag-, HA-, hASH1-transfected human adenocarcinoma cell lines to study proteins associated with hASH1 and its DNA binding sites. In the near future, we will clarify important molecules involved in neuroendocrine differentiation, and more precise molecular mechanisms of lung epithelial cell and lung carcinoma cell differentiation. Less