Oligosaccharide-linked acyl carrier protein, a novel transmethylase inhibitor, from porcine liver inhibits cell growth

We have previously reported on the identification of the endogenous transmethylation inhibitor oligosaccharide-linked acyl carrier protein (O-ACP). In this study, the role of the transmethylation reaction on cell cycle progression was evaluated using various transmethylase inhibitors, including O-ACP. O-ACP significantly inhibited the growth of various cancer cell lines, including NIH3T3, ras-transformed NIH3T3, MDA-MB-231, HT-1376, and AGS. In addition, exposure of ras-transformed NIH3T3 to O-ACP caused cell cycle arrest at the G₀/G₁ phase, which led to a decrease in cells at the S phase, as determined by flow cytometry. In contrast, transmethylase inhibitors did not affect the expression of p21^WAF1/Cip1, a well known inhibitor of cyclin dependent kinase, indicating that the cell cycle arrest by transmethylase inhibitors might be mediated by a p21^WAF1/Cip1-independent mechanism. Therefore, O-ACP, a novel transmethylase inhibitor, could be a useful tool for elucidating the novel role of methylation in cell proliferation and cell cycle progression.