The Effect And The Regulation Of Elongator Complex Protein 3 (ELP3) On A549 Lung Cancer Cell

Epigenetic modifications such as DNA methylation and histone modifications play an important role on the regulation of gene expression. Epigenetic modification aberration resulted in a malignant phenotype during tumorigenesis. Elongator complex protein 3 (ELP3) is a histone acetyltransferase, and related to transcription regulation. ELP3 has an iron sulfur cluster domain (SAM), which affect DNA demethylation. But how ELP3 regulating cell the malignant phenotype of lung cancer cells is unclear. The purpose of this experiment is to study the expression,localization, and cell function of ELP3 in A549 lung cancer cell line.In this study, firstly, the expression of ELP3 were detected in different cell lines. The results showed that ELP3 mRNA were expressed higher in cancer cell lines than in lung epithelial cells(P<0.05), and the A549 lung cancer cell lines has the highest ELP3 mRNA expression, so it was selected for the following study. Secondly, pGPU6/GFP/Neo siRNA expression vector were constructed to knock down the expression of ELP3. The vector were transfected into A549 cells by liposome transfection method, after screened with G418, ELP3 expression were effectively suppressed by 85.4% in A549 cells. The malignant phenotype of A549 cells after transfection were studied by MTT, Traswell and anchor-independent growth, the results show that compared with control group, cell proliferation decreased by 24.61%(p<0.01), cell migration decreased by 52.38%(p<0.05), invasion ability decreased by 37.90%(p<0.01) and anchor-independent growth decreased by 83.57%(p<0.01), respectively.To further study the possible regulation mechanism of ELP3, we examined the change of related genes expression and epigenetic modifications in the corresponding promoter region after knockdown ELP3. Real-time PCR results showed that the expression of BCL2, C-erbA, C-JUN, C-myc, N-myc the mRNA significantly decreased, and the expression of KLF4 was increased and not changed in SOX2 and K-ras. Bisulfite PCR results showed that, compared with the control group, the methylation level of the promoter region was increased by 5.00% in K-ras gene and 8.46% in BCL2. The methylation of alpha satellite repeats was decreased by 10.00% and retroviral LTR sequence of minisatellite MS32 was increased by 18.30%. CHIP assay showed that knockdown ELP3 suppressed histone modifications H3K9me3, H3K4me3, H3K27me3 at SOX2 and C-MYC promoter regions.In conclusion, the expression of ELP3 was upregulated in lung cancer cells. After knockdown of ELP3, The expression of oncogenes was decreased and DNA methylation were imcreased at the promoter region of related oncogenes, In addition, The histone motification status in related gene promoter region were also changed. Our results suggested that ELP3 have a function of DNA demethylation, ELP3 may affect DNA methylation and histone modification status in the promoter region of related gene, affected gene expression, and influenced the proliferation, migration, invasion, and anchor-dependent growth of lung cancer cells.