Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, PR China.
Oncol Rep. 2013 Aug;30(2):773-82. doi: 10.3892/or.2013.2520. Epub 2013 Jun 5.
The phosphatidylinositol 3‑kinase (PI3K)/Akt signaling pathway plays a crucial role in tumorigenesis and tumor progression by promoting cell proliferation and inhibiting apoptosis, a process closely associated with multidrug resistance (MDR) of tumors. LY294002 is a commonly used pharmacological inhibitor that acts at the ATP‑binding site of the PI3K enzyme, selectively inhibiting the PI3K/Akt pathway. In the present study, we evaluated the effect of LY294002 on the chemosensitivity of gastric cancer cells to vincristine (VCR) in vitro and in vivo and investigated the possible underlying cellular mechanisms. The effect of LY294002 on cell viability, apoptosis induction and inhibition of tumor growth was analyzed using MTT and TUNEL assay in in vitro and in vivo models of gastric cancer. Intracellular accumulation of VCR was determined by high performance liquid chromatography. The activity of the PI3K/Akt pathway was evaluated by western blot analysis. Furthermore, reverse transcription PCR and immunohistochemistry were performed to determine the mRNA and protein expression levels of MDR1/ P-glycoprotein (P‑gp) and apoptosis‑related factors. We found that gastric cancer cells treated with LY294002 showed a significant inhibition of PI3K/Akt activity. The PI3K inhibitor LY294002 combined with VCR worked synergistically to promote growth inhibition, induce apoptosis and increase the intracellular drug accumulation in gastric cancer cell lines. Similarly, LY294002 could cooperate with VCR to reduce tumor growth in a gastric cancer model in vivo. Finally, LY294002 was able to decrease the expression of MDR1/P‑gp, Bcl‑2 and XIAP, and upregulate expression of Bax and caspase‑3, thereby enhancing chemosensitivity to VCR by inhibiting a drug pump and inducing apoptosis. These results suggested that the PI3K/Akt inhibitor LY294002 can enhance chemosensitivity of human gastric cancer to VCR. This preclinical evaluation of a rational combination of LY294002 and VCR may provide a new strategy to resolve the MDR of gastric cancer.
磷脂酰肌醇 3-激酶（PI3K）/Akt 信号通路通过促进细胞增殖和抑制细胞凋亡来在肿瘤发生和肿瘤进展中发挥关键作用，这个过程与肿瘤的多药耐药（MDR）密切相关。LY294002 是一种常用的药理学抑制剂，作用于 PI3K 酶的 ATP 结合位点，选择性地抑制 PI3K/Akt 通路。本研究评估了 LY294002 对体外和体内胃癌细胞对长春新碱（VCR）化疗敏感性的影响，并探讨了可能的潜在细胞机制。采用 MTT 和 TUNEL 检测法在体外和体内胃癌模型中分析 LY294002 对细胞活力、凋亡诱导和肿瘤生长抑制的影响。通过高效液相色谱法测定 VCR 的细胞内蓄积。通过 Western blot 分析评估 PI3K/Akt 通路的活性。此外，还进行了逆转录 PCR 和免疫组织化学检测，以确定 MDR1/P-糖蛋白（P-gp）和凋亡相关因子的 mRNA 和蛋白表达水平。我们发现，用 LY294002 处理的胃癌细胞显示出 PI3K/Akt 活性的显著抑制。PI3K 抑制剂 LY294002 与 VCR 联合使用可协同促进生长抑制、诱导凋亡并增加胃癌细胞系中的细胞内药物蓄积。同样，LY294002 可与 VCR 合作在体内胃癌模型中减少肿瘤生长。最后，LY294002 能够降低 MDR1/P-gp、Bcl-2 和 XIAP 的表达，上调 Bax 和 caspase-3 的表达，从而通过抑制药物泵和诱导凋亡来增强对 VCR 的化疗敏感性。这些结果表明，PI3K/Akt 抑制剂 LY294002 可增强人胃癌对 VCR 的化疗敏感性。对 LY294002 和 VCR 合理联合的临床前评估可能为解决胃癌的 MDR 提供新策略。
