AntiCancer Inc, 7917 Ostrow St, San Diego, CA, 92111, USA; Department of Surgery, University of California, San Diego, 9300 Campus Point Drive #7220, La Jolla, CA, 92037-7220, USA; Department of Gastroenterological Surgery, Yokohama City University Graduate School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama, 236-0004, Japan.
AntiCancer Inc, 7917 Ostrow St, San Diego, CA, 92111, USA.
Biochem Biophys Res Commun. 2020 Dec 17;533(4):1034-1038. doi: 10.1016/j.bbrc.2020.09.108. Epub 2020 Oct 3.
Methionine addiction is a fundamental and general hallmark of cancer. Methionine addiction prevents cancer cells, but not normal cells from proliferation under methionine restriction (MR). Previous studies reported that MR altered the histone methylation levels in methionine-addicted cancer cells. However, no study has yet compared the status of histone methylation status, under MR, between cancer cells and normal cells. In the present study, we compared the histone methylation status between cancer cells and normal fibroblasts of H3K4me3 and H3K9me3, using recombinant methioninase (rMETase) to effect MR. Human lung and colon cancer cell lines and human normal foreskin fibroblasts were cultured in control medium or medium with rMETase. The viability of foreskin fibroblasts was approximately 10 times more resistant to rMETase than the cancer cells in vitro. Proliferation only of the cancer cells ceased under MR. The histone methylation status of H3K4me3 and H3K9me3 under MR was evaluated by immunoblotting. The levels of the H3K4me3 and H3K9me3 were strongly decreased by MR in the cancer cells. In contrast, the levels of H3K4me3 and H3K9me3 were not altered by MR in normal fibroblasts. The present results suggest that histone methylation status of H3K4me3 and H3K9me3 under MR was unstable in cancer cells but stable in normal cells and the instability of histone methylation status under MR may determine the high methionine dependency of cancer cells to survive and proliferate.
甲硫氨酸成瘾是癌症的一个基本和普遍特征。甲硫氨酸成瘾可阻止癌细胞在甲硫氨酸限制（MR）下增殖，但不能阻止正常细胞增殖。先前的研究报告称，MR 改变了甲硫氨酸成瘾癌细胞中的组蛋白甲基化水平。然而，尚无研究比较过 MR 下癌细胞和正常细胞之间的组蛋白甲基化状态。在本研究中，我们使用重组甲硫氨酸酶（rMETase）来实现 MR，比较了 H3K4me3 和 H3K9me3 之间的组蛋白甲基化状态在癌细胞和正常成纤维细胞之间的差异。将人肺癌和结肠癌细胞系和人正常包皮成纤维细胞在对照培养基或含 rMETase 的培养基中培养。体外 rMETase 对包皮成纤维细胞的存活率的抗性大约是癌细胞的 10 倍。只有癌细胞在 MR 下停止增殖。通过免疫印迹评估了 MR 下 H3K4me3 和 H3K9me3 的组蛋白甲基化状态。MR 强烈降低了 H3K4me3 和 H3K9me3 的水平。相比之下，MR 对正常成纤维细胞中的 H3K4me3 和 H3K9me3 水平没有影响。本研究结果表明，MR 下 H3K4me3 和 H3K9me3 的组蛋白甲基化状态在癌细胞中不稳定，而在正常细胞中稳定，MR 下组蛋白甲基化状态的不稳定性可能决定了癌细胞对甲硫氨酸的高依赖性，以维持生存和增殖。
