Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA 30602, United States.
Biochem Pharmacol. 2010 Jun 15;79(12):1727-35. doi: 10.1016/j.bcp.2010.02.005. Epub 2010 Feb 18.
The p38 mitogen-activated protein kinase (MAPK) signaling pathways activated during cytostasis induced by Ca(2+)-independent phospholipase A2 (iPLA2) inhibition in prostate cancer cells were investigated. iPLA2 inhibition using siRNA, or the selective inhibitor bromoenol lactone (BEL) and it's enantiomers, decreased growth in LNCaP (p53 positive) and PC-3 (p53 negative) human prostate cancer cells. Decreased cell growth correlated to time- and concentration-dependent activation of the mitogen-activated protein kinase p38 in both cell lines. Inhibition of cytosolic iPLA(2)beta using S-BEL, induced significantly higher levels of P-p53, p53, p21 and P-p38 expression than inhibition of microsomal iPLA2 gamma using R-BEL. Inhibition of p38 using SB202190 or SB203580 inhibited BEL-induced increases in P-p53 (ser15), p53 and p21, and altered the number of cells in G1 in LNCaP cells, and S-phase in PC-3 cells. BEL treatment also induced reactive species in PC-3 and LNCaP cells, which was partially reversed by pretreatment with N-acetyl-cysteine (NAC). NAC subsequently inhibited BEL-induced activation of p38 and p53 in LNCaP cells. In addition, treatment of cells with NAC partially reversed the effect of BEL on cell growth and preserved cell morphology. Collectively, these data demonstrate the novel findings that iPLA2 inhibition activates p38 by inducing reactive species, and further suggest that this signaling kinase is involved in p53 activation, cell cycle arrest and cytostasis.
研究了细胞静止诱导过程中钙非依赖性磷脂酶 A2（iPLA2）抑制激活的 p38 丝裂原活化蛋白激酶（MAPK）信号通路，在前列腺癌细胞中。使用 siRNA 或选择性抑制剂溴烯内酯（BEL）及其对映体抑制 iPLA2，可降低 LNCaP（p53 阳性）和 PC-3（p53 阴性）人前列腺癌细胞的生长。在这两种细胞系中，细胞生长减少与时间和浓度依赖性的丝裂原活化蛋白激酶 p38 激活相关。使用 S-BEL 抑制细胞质 iPLA（2）β，诱导的 P-p53、p53、p21 和 P-p38 表达水平明显高于使用 R-BEL 抑制微粒体 iPLA2γ。使用 SB202190 或 SB203580 抑制 p38 可抑制 BEL 诱导的 P-p53（ser15）、p53 和 p21 的增加，并改变 LNCaP 细胞中 G1 期和 PC-3 细胞中 S 期的细胞数量。BEL 处理还诱导了 PC-3 和 LNCaP 细胞中的活性物质，这部分被 N-乙酰半胱氨酸（NAC）预处理所逆转。NAC 随后抑制了 BEL 诱导的 LNCaP 细胞中 p38 和 p53 的激活。此外，用 NAC 处理细胞部分逆转了 BEL 对细胞生长的影响，并保持了细胞形态。总之，这些数据表明了 iPLA2 抑制通过诱导活性物质激活 p38 的新发现，并进一步表明这种信号激酶参与了 p53 激活、细胞周期停滞和细胞静止。
