Effects And Mechanisms Of Differentiation Induced By Retinoic Acid On Human Neuroblastoma SK-N-SH Cells

In this study, after we investigated the differentiation effects of the human neuroblastoma SK-N-SH cells induced by Retinoic Acid (RA), we use proteomics to analyze the differently expressed proteins , in order to know the molecular mechanisms of carcinogenesis and malignant phenotypic reversion in a systematic level., and to find a new way of tumor differentiation research.The results showed that after treated with 1μmol/L RA, the proliferation rate of SK-N-SH cells was inhibited, the inhitbion rate amounts to 36.16%, and the cell cycle was arrested at G₀/G₁ phase; the morphology and ultrastructure of SK-N-SH cells changed, cells became multipolar with several neurites, the cell bodies were smaller with long axonal processes between one another to formed ganglion,the microvilli in the cell faces were rare, the nucleolus reduced while the euchromatin increased, and the organelles developed; The immunocytochemistry assey also revealed that the expression level of oncogene including c-myc,c-fos was downregulated , and the expression level of tumor suppressor gene including p53,p27 was upregulated, and at the same time , the expression of the neuronal markers of terminal differentiation, including NSE , MAP2 and Synaptophysin were strongly positive after treatment. Were found 26 proteins differently expressed after treated , and 16 proteins were identified . In these 16 proteins , 10 proteins were upregulated , such as Rab GDP dissociation inhibitor , RABGAP1L protein (RAB GTPase activating protein 1-like ) , DNM1L protein , SP110 , Myoneurin , DNA topoisomerase II binding protein, Human iroquois-class homeodomain protein IRX-5 and Alpha-enolase, BCL2/adenovirus E1B 19kDa interacting protein 1 (BNIP1) and PHD finger protein 20-like 1 were new proteins; and 6 proteins were identified lower expression , such as cell division cycle 73, interleukin-8, RAB37, Methyltransferase (DNMT) and Vav 3 oncogene protein , and HP protein was disappeared after treated. And DNMlL,Myoneurin,IRX-5 were first found in tumor differentiation, while PHD finger,SP110,IRX-5 were first found in neuron or neuroblastoma differentiation. In conclusion, 1μmol/L RA can induce SK-N-SH cells into terminal differentiation, via proliferation inhibited, G₀/G₁ phase arrested, downregulated oncogene expression, upregulated suppressor gene expression and induced expression of neuronal markers. At the same time, the proteomics of the SK-N-SH cells were changed after induced, we identified 16 differently expressed proteins during differentiation, including regulators of gene expression , proteins of tumor gene and neuronal proteins, and so on, and it is possible to get a system understanding of the molecular mechanisms of RA induced differentiation.