| Background:Gastric cancer (GC) is one of the most common carcinoma and the third major contributor to cancer mortality worldwide. Despite the improvement in medical and surgical therapy has lowered mortality of GC in the last decades, the 5-year survival rate for advanced GC remains unsatisfactory with< 10-25%. Thus, a detailed molecular understanding of GC pathogenesis and more effective drugs for GC patients are urgently needed. The histone acetyltransferase (HAT) p300 and CBP are found play crucial roles in cell cycle, DNA synthesis and cellular differentiation. In malignant tumors, such as human prostate cancer (PCa) and melanoma, inhibition of p300/CBP could decreases the proliferation and invasive capacity of tumor cells. C646, a small molecule inhibitor of p300/CBP, was reported had anti-tumor activity in many cancer cell lines in recent years. However, its effects on gastric cancer cells have not been extensively investigated. To find new treatment targets and more effective drugs for GC, we demonstrate the expression of p300/CBP in gastric cancer cells in this study. Futhermore, we will investigate the effects of C646 on the GC cells and its potential mechanisms.Objective:To investigate the expression level of p300/CBP in normal gastric epithelial cell (GES-1) and 5 gastric cancer cell lines (KATO III, SGC-7901, BGC-823, MKN45 and MGC-803) and analysis the expression difference between the normal gastric epithelial cells and gastric cancer cell lines. To find the changes of cell proliferation, cell migration and invasion, cell cycle and apoptosis in the 5 gastric cancer cell lines after treated by p300/CBP inhibitor C646. To explore the potential molecular mechanisms of C646 in affectting the biology functions of gastric cancer cells.Methods:The gene and protein levels of p300/CBP expression in normal gastric epithelial cell (GES-1) and 5 gastric cancer cell lines (KATO â…¢, SGC-7901, BGC-823, MKN45 and MGC-803) were quantified by qRT-PCR and Western Blot.The normal gastric epithelial cell (GES-1) and 5 gastric cancer cell lines were treated with histone acetyltransferase (HAT) p300/CBP inhibitor C646. The effects of p300/CBP inhibition on cell proliferation, cell migration and invasion, cell cycle and apoptosis were detected by using CCK-8 kit, scratch assay, transwell assay and flow cytometer, respectively.Western Blot and qRT-PCR were carried out to detect relevant expression of MET, AKT, p-AKT, Erk, p-Erk, BCL2, Cyclin D1, MMP7 and MMP9 in the treated cell lines.Results:The p300/CBP expression was evaluated in the 6 cell lines by using qRT-PCR and western Blot. The results indicated that p300/CBP was highly expressed in the 5 gastric cancer cell lines compared with normal gastric epithelial cell both at the mRNA and protein levels (P<0.05).In vitro experiment, we treated the normal gastric epithelial cell and 5 gastric cancer cell lines (KATO â…¢, SGC-7901, BGC-823, MKN45 and MGC-803) with different concentrations of C646, DMSO treatment as control. CCK-8 detected that the cell proliferation of all the above cell lines was significantly inhibited after C646 treated (P<0.05). The inhibition of MKN45 and MGC-803 proliferation were most severe among the 5 gastric cancer cell lines. The flow cytometry analysis revealed that C646 treatment could induce cell cycle arrest and cell apoptosis in gastric cancer cells. Scrach assay and transwell assay found that C646 could significantly inhibit the migration and invasion of gastric cancer cell lines except the SGC-7901 cell.We also examined the associated signaling molecules by using qRT-PCR and Western Blot. It is impressive that once p300/CBP was inhibited after C646 treatment, the protein levels of MET, AKT and p-AKT were declined. However, the variations of MET, MM7 and MMP9 mRNA levels after C646 treated were very complicated.Conclusions:The histone acetyltransferase (HAT) p300/CBP was overexpressed in the gastric cancer cell lines compared with normal gastric epithelial cell. Experiments in vitro proved that C646 could inhibit the cell growth, suppress the cell migration and invasion ability, block the cell cycle process and promote cell apoptosis in gastric cancer cells. Once p300/CBP was inhibited by C646, the protein levels of MET, AKT and p-AKT were down-regulated, suggesting that p300/CBP participated in regulating the biological function of gastric cancer cells through the oncoprotein MET and AKT pathway. Moreover, C646 might have anticancer effects by mean of blocking the role of p300/CBP. |
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