Effect of DNA methyltransferases 1 inhibition on proliferation, invasion, and metastasis in ACC-M line / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of DNA methyltransferases 1 (DNMT-1) inhibition on the ACC-M cells in vitro and in vivo and discuss the role of DNMT-1 in the development, invasion and metastasis of salivary adenoid cystic carcinoma (SACC).</p><p><b>METHODS</b>ACC-M cells of stable DNMT-1 inhibition were established in a previous research. In vitro, the growth and invasion of ACC-M cells which stably inhibited DNMT-1 were detected and analyzed by methyl thiazolyl tetrazolium (MTT) growth curve, flow cytometry, plating efficiency and invasion assay. In vivo, the growth and metastasis of ACC-M cells which persistently inhibited DNMT-1 were observed and analyzed by subcutaneous injection and tail vein injection into the nude mice.</p><p><b>RESULTS</b>In vitro, the doubling time [(34.7 +/- 2.1) h], S phase fraction [(17.4 +/- 1.7)%], plating efficiency [(43.0 +/- 1.3)%] of ACC-M cells was significantly different from those of blank [(26.2 +/- 3.1) h, (31.5 +/- 2.0)%, (71.0 +/- 4.7)%], empty load control [(28.4 +/- 3.9) h, (39.0 +/- 2.0)%, (66.0 +/- 5.2)%], P < 0.05, and the invasion ability was not significantly different among these groups (P > 0.05). In vivo, the subcutaneous tumor forming rate (6/10), volume [(2.18 +/- 0.83) mm(3)], weight [(0.0156 +/- 0.0046) g] of ACC-M cells was also significantly lower than that of blank [10/10, (155.44 +/- 1.67) mm(3), (0.0724 +/- 0.0157) g], empty load control [10/10, (147.46 +/- 1.73) mm(3), (0.0729 +/- 0.0177) g], P < 0.05, but the rate of lung metastasis was not significantly different among these groups (P > 0.05), and the masses (2.0 +/- 0.5), diameter (70.0 +/- 20.3) microm of ACC-M cells was significantly lower than that of blank [(28.0 +/- 5.5), (195 +/- 25.4) microm], empty load control [(27.0 +/- 4.5), (190.0 +/- 19.9) microm], P < 0.05.</p><p><b>CONCLUSIONS</b>Inhibition of DNMT-1 is able to inhibit the proliferation and metastasis of ACC-M cells in vitro and in vivo.</p>

DNA methylation in salivary adenoid cystic carcinoma cell lines / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the promoter methylation status of tumor suppressor gene and the relationship between promoter methylation and mRNA, protein expression of tumor suppressor gene in salivary adenoid cystic carcinoma (ACC) cell lines.</p><p><b>METHODS</b>Promoter methylation status of E-cad, p16, RASSF1A, DAPK, and MGMT was determined by methylation-specific polymerase chain reaction (MSP) in ACC cell lines, ACC-2, ACC-3, and ACC-M. E-cad, p16 protein and mRNA expression was also examined by IHC and RT-PCR in 3 ACC cell lines.</p><p><b>RESULTS</b>All the three salivary ACC cell lines exhibited E-cad, p16 promoter methylation, but no methylation of RASSF1A, DAPK, and MGMT was found. There was p16 protein and mRNA expression but no E-cad expression in 3 ACC cell lines.</p><p><b>CONCLUSIONS</b>The results suggest that in ACC cell lines, promoter methylation of E-cad, p16 is a common event, and promoter methylation may be one of the major mechanism for inactivation of E-cad.</p>