Apoptosis and inhibition of the phosphatidylinositol 3-kinase/Akt signaling pathway in the anti-proliferative actions of dehydroepiandrosterone
Apoptosis and inhibition of the phosphatidylinositol 3-kinase/Akt signaling pathway in the anti-proliferative actions of dehydroepiandrosterone
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DOI：
10.1007/s00535-005-1574-3
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发表时间：
2005-05-01
影响因子：
6.3
通讯作者：
Matsuzaki, Y
中科院分区：
文献类型：
--
作者：
Jiang, YF;Miyazaki, T;Matsuzaki, Y
脱氢表雄酮（DHEA）是一种内源性类固醇，主要在肾上腺皮质合成；它以硫酸盐共轭形式（DHEA-S）存在于血浆中。药理剂量的脱氢表雄酮对实验动物的恶性细胞系和某些肿瘤表现出抗增殖作用。本研究的目的是评估这些类固醇对人类癌细胞系增殖的影响。方法。用脱氢表雄酮（DHEA）或脱氢表雄酮（DHEA- s）在0 ~ 200 μ M作用24h或100 μ M作用8 ~ 72h，分别用3-[4,5-二甲基噻唑]-2yl-2,5-二苯基溴化四唑（MTT）法和流式细胞术观察对HepG2和HT-29细胞株生长、细胞周期和细胞凋亡的影响。Western blotting检测DHEA对HepG2细胞中PI3K /Akt信号通路的影响。结果。DHEA显著抑制HepG2和HT-29细胞的生长，并呈剂量依赖性和时间依赖性。这种抑制作用在HepG2细胞中比在HT-29细胞中更大。在DHEA处理下，两种细胞系在G0/G1期均有积累。然而，凋亡仅在HepG2细胞中显著增加。相比之下，DHEA-S对两种细胞系的生长抑制和细胞抑制作用要弱得多，并且未检测到凋亡。在DHEA处理的HepG2细胞中，凋亡与Akt磷酸化（Thr（308）和Ser(473)）显著降低相关，表明DHEA抑制PI3K/Akt信号通路诱导HepG2细胞凋亡。结论。这些结果表明，通过抑制PI3K/Akt信号通路诱导细胞凋亡是DHEA在某些肿瘤中的抗增殖机制之一，但DHEA在不诱导细胞凋亡的情况下也促进细胞周期阻滞。
Background Dehydroepiandrosterone (DHEA) is an endogenous steroid that is synthesized mainly in the adrenal cortex; it is found in plasma as the sulfate-conjugated form (DHEA-S). Pharmacological doses of DHEA exhibit anti-proliferative effects on malignant cell lines and some tumors in experimental animals. The purpose of this study was to evaluate the effect of these steroids on proliferation in human cancer cell lines. Methods. HepG2 and HT-29 cell lines were treated with DHEA or DHEA-S at 0-200 mu M for 24h or at 100 mu M for 8-72h, and then effects on cell growth, and the cell cycle and on apoptosis, were evaluated by 3-[4,5-dimethylthiazol]-2yl-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively. Also, the effect of DHEA on phosphatidylinositol 3-kinase (PI3K)/Akt signaling was investigated in HepG2 cells by Western blotting. Results. The growth of HepG2 and HT-29 cells was significantly inhibited by DHEA, in a dose- and time-dependent manner. This inhibition was greater in HepG2 than in HT-29 cells. Accumulation at G0/G1 phase in both cell lines was observed with DHEA treatment. However, apoptosis increased significantly only in HepG2 cells. In contrast, DHEA-S exhibited much weaker growth inhibitory and cytostatic effects on both cell lines, and apoptosis was not detected. In HepG2 cells treated with DHEA, apoptosis was associated with markedly reduced Akt phosphorylation (Thr(308) and Ser(473)), suggesting that DHEA inhibited the PI3K/Akt signaling to induce apoptosis in these cells. Conclusions. These results suggest that the induction of apoptosis through the inhibition of the PI3K/Akt signaling pathway is one of the anti-proliferative mechanisms of DHEA in certain tumors, but that DHEA also promotes cell-cycle arrest without the induction of apoptosis.