Methionine inhibits cellular growth dependent on the p53 status of cells
Methionine inhibits cellular growth dependent on the p53 status of cells
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DOI：
10.1016/j.amjsurg.2006.07.016
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发表时间：
2007-02-01
影响因子：
3
通讯作者：
Grizzle, William E.
中科院分区：
文献类型：
--
作者：
Benavides, Maximo A.;Oelschlager, Denise K.;Grizzle, William E.
背景资料：蛋氨酸是一种必需氨基酸，对正常生长和发育很重要，因为它是蛋白质和多胺合成以及甲基化反应所必需的。据报道，高浓度的甲硫氨酸抑制人乳腺肿瘤衍生的MCF-7细胞中的细胞生长和基因表达。这些作用被认为是由p53的调节介导的。然而，这一观察结果的普遍性以及p53在蛋氨酸诱导的生长抑制中的确切作用还有待确定。为了确定甲硫氨酸对细胞生长的抑制是否适用于其他细胞系，并进一步表征p53在甲硫氨酸诱导的生长抑制中的作用，我们已经评估了甲硫氨酸对表达天然p53的细胞中的细胞生长和增殖以及p53表达的影响，例如，乳腺癌MCF-7细胞和前列腺癌LNCaP细胞，以及表达突变（点）形式的p53的细胞，例如前列腺癌DU-145细胞。这些细胞系用不同浓度的L-甲硫氨酸处理。采用细胞活力测定和细胞增殖标记物Ki-67免疫组化染色法检测L-蛋氨酸对细胞生长的影响。通过逆转录聚合酶链反应（RT-PCR），免疫组化和Western blot分析蛋氨酸对p53表达的影响进行了评估。p53在L-甲硫氨酸介导的生长抑制的作用进行了评估，使用短干扰RNA的p53（siRNA-p53），免疫沉淀，和直接的DNA sequencing.Results：我们证明，甲硫氨酸在浓度为1至5毫克/毫升抑制MCF-7和LNCaP细胞的生长。与生长抑制相关，甲硫氨酸还分别在mRNA和蛋白水平上抑制天然p53表达。此外，用siRNA-p53转染以敲低p53表达，增加了LNCaP细胞的细胞生长和增殖，即使当它们暴露于甲硫氨酸时。相反，相同的处理没有减少DU-145细胞的生长或增殖。此外，突变的p53在mRNA或蛋白质水平的表达没有altered.Conclusion：我们的研究结果扩展到其他细胞系之前的观察，并证明高浓度的蛋氨酸抑制天然的，但不是突变的p53的表达。这些对细胞生长的抑制作用部分是由于可能通过p53依赖性途径抑制细胞增殖。(c)2007 Excerpta Medica Inc. All rights reserved.
Background: Methionine, an essential amino acid, is important for normal growth and development, as it is required for both protein and polyamine synthesis as well as in methylation reactions. It has been reported that high concentrations of methionine inhibit cellular growth and gene expression in the human breast tumor-derived MCF-7 cells. These effects are thought to be mediated by the modulation of p53. However,the generalizability of this observation and the precise role of p53 in methionine-induced growth suppression needs to be determined.Methods: To determine if the inhibition of cell growth by methionine applies to other cell lines and to characterize further the role of p53 in methionme-induced growth suppression, we have assessed the effects of methionine on cellular growth and proliferation and p53 expression in cells expressing native p53, eg, breast cancer MCF-7 cells and prostate cancer LNCaP cells, and also in cells expressing a mutated (point) form of p53, eg, prostate cancer DU-145 cells. These cell-lines were treated with varying concentrations Of L-methionine. The effects Of L-methionine on cell growth were assyed by using cell viability assays and immunostaining for Ki-67, a cell proliferation marker. The effects of methionine on p53 expression were assessed by using reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and Western blot analysis. The role of p53 in L-methionine-mediated growth suppression was evaluated using short-interference RNA for p53 (siRNA-p53), immunoprecipitation, and direct DNA sequencing.Results: We demonstrated that methionine at a concentration of I to 5 mg/mL inhibited the growth of both MCF-7 and LNCaP cells. In association with the inhibition of growth, methionine also inhibited native p53 expression at the mRNA and protein levels, respectively. Furthermore, transfection with siRNA-p53, to knock down p53 expression, increased cell growth and proliferation of the LNCaP cells even when they were exposed to methionine. In contrast, the same treatment did not diminish growth or proliferation of the DU-145 cells. Also, the expression of mutated p53 at the mRNA or protein levels was not altered.Conclusion: Our results extend a prior observation to other cell lines and demonstrate that high concentrations of methionine suppress the expression of native but not mutated p53. These inhibitory effects on cellular growth are, in part, due to inhibition of cellular proliferation probably via a p53-dependent pathway. (c) 2007 Excerpta Medica Inc. All rights reserved.