Department of Biophysics, Panjab University, Chandigarh, 160014, India.
Exp Mol Pathol. 2012 Aug;93(1):135-46. doi: 10.1016/j.yexmp.2012.04.019. Epub 2012 Apr 25.
Phosphatidylinositol 3-kinase (PI3-K) and Akt (protein kinase B), are both essential signaling molecules that are up-regulated in various cancers. Here, we examined the molecular mechanisms by which PI3-K and Akt expression are regulated by glycogen synthase kinase-3β (GSK-3β) and the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in the early stages of experimental colon carcinogenesis. 1,2-dimethylhydrazine (DMH) was utilized for the induction of colon cancer while piroxicam, a traditional non-steroidal anti-inflammatory drug and c-phycocyanin, a biliprotein from Spirulina platensis (cyanobacterium) as the chemopreventive agents. Western blotting and immunofluorescence results indicated that the expression of PI3-K and Akt was promoted in the DMH group while least apoptosis was detected in this group as analyzed by Hoechst 33342-propidium iodide co-staining. DMH group further detected lower GSK-3β and PTEN expression as compared to other groups. Piroxicam and c-phycocyanin treatment resulted significant apoptotic cell death while showing low PI3-K and Akt expressions. Mitochondrial membrane potential (ΔΨ(M)) alterations (examined by JC-1 and rhodamine 123 labeling of colonocytes) and fluorescence intensity measurement of ROS level, were also analyzed showing the raised ΔΨ(M) while reduced ROS levels in DMH group, however piroxicam and c-phycocyanin treatment resulted in falling of ΔΨ(M) although both stimulated the ROS production as analyzed by flow cytometry. The present study thus identified that piroxicam, a traditional NSAID and c-phycocyanin, a newly discovered COX-2 selective inhibitor, constitute remarkable chemopreventive targets in mediating apoptosis in the DMH induced early rat colon carcinogenesis via regulating PI3-K/Akt/GSK-3β/PTEN signaling pathways. Further, a combination of the two drugs provides a better therapeutic option, than the monotherapy regimen.
磷脂酰肌醇 3-激酶（PI3-K）和 Akt（蛋白激酶 B）都是在各种癌症中上调的必需信号分子。在这里，我们研究了糖原合酶激酶-3β（GSK-3β）和第 10 号染色体缺失的磷酸酶和张力蛋白同源物（PTEN）调节 PI3-K 和 Akt 表达的分子机制在实验性结肠癌发生的早期阶段。1,2-二甲基肼（DMH）用于诱导结肠癌，而吡罗昔康是一种传统的非甾体抗炎药，藻蓝蛋白 c-phycocyanin 是螺旋藻（蓝藻）中的一种双蛋白。Western blot 和免疫荧光结果表明，PI3-K 和 Akt 的表达在 DMH 组中得到促进，而在该组中检测到最少的细胞凋亡，通过 Hoechst 33342-碘化丙啶共染色进行分析。与其他组相比，DMH 组进一步检测到较低的 GSK-3β 和 PTEN 表达。吡罗昔康和藻蓝蛋白处理导致显著的细胞凋亡死亡，同时显示低 PI3-K 和 Akt 表达。还分析了线粒体膜电位（ΔΨ（M））变化（通过 JC-1 和罗丹明 123 标记结肠细胞进行检测）和 ROS 水平的荧光强度测量，结果显示 DMH 组的 ΔΨ（M）升高，ROS 水平降低，然而，吡罗昔康和藻蓝蛋白处理导致 ΔΨ（M）下降，尽管两者通过流式细胞术分析都刺激了 ROS 的产生。因此，本研究表明，吡罗昔康，一种传统的 NSAID 和藻蓝蛋白 c-phycocyanin，一种新发现的 COX-2 选择性抑制剂，通过调节 PI3-K/Akt/GSK-3β/PTEN 信号通路，在 DMH 诱导的早期大鼠结肠癌发生中构成显著的化学预防靶点，诱导细胞凋亡。此外，两种药物的联合使用提供了比单一药物治疗方案更好的治疗选择。
