Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, Heilongjiang 150030, P.R. China.
Mol Med Rep. 2018 Jun;17(6):8289-8299. doi: 10.3892/mmr.2018.8868. Epub 2018 Apr 11.
Paclitaxel is a diterpenoid compound, derived from the pacific yew (Taxus brevifolia) berry, which exhibits antineoplastic effects against various types of cancer. However, the antitumor effects and the molecular mechanisms of paclitaxel on canine CHMm cells remain to be elucidated. The aim of the present study was to investigate the antitumor effects of paclitaxel on CHMm cells and identify relevant signal transduction pathways modulated by paclitaxel using multiple methods including MTT assay, flow cytometry, acridine orange/ethidium bromide staining, transmission electron microscopy, determination of cellular reactive oxygen species (ROS), superoxide dismutase (SOD) and malondiadehyde (MDA) and western blotting, the data indicated that paclitaxel decreased cell viability, induced G2/M‑phase cell cycle arrest, suppressed the expression of cyclin B1 and induced apoptosis in a dose‑dependent manner. In addition, paclitaxel upregulated the expression of Bax and cytochrome c, but reduced expression of apoptosis regulator Bcl‑2, resulting in activation of caspase‑3, chromatin condensation, karyopyknosis, intracellular vacuolization, increased production of ROS and MDA, and decreased activity of SOD. However, these effects were inhibited when CHMm cells were treated with N‑acetyl‑L‑cysteine. Furthermore, treatment with paclitaxel inhibited the level of of phospho (p)‑RAC‑α serine/threonine‑protein kinase (AKT) and p‑ribosomal protein S6 kinase proteins, and promoted phosphorylation of P38 mitogen‑activated protein kinase (MAPK) and p‑90 kDa ribosomal protein S6 kinase 1 proteins in CHMm cells. It was observed that paclitaxel in combination with pharmacological inhibitors of the P38 and phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K) signaling pathways (SB203580 and LY294002, respectively) exerted synergistic inhibitory effects on the proliferation of the CHMm cells. The results of the present study demonstrated that paclitaxel inhibited tumor cell proliferation by increasing intrinsic apoptosis through inhibition of the PI3K/AKT signaling pathway and activation of MAPK signaling pathway in CHMm cells.
紫杉醇是一种二萜类化合物，来源于太平洋紫杉（Taxus brevifolia）浆果，对各种类型的癌症具有抗肿瘤作用。然而，紫杉醇对犬 CHMm 细胞的抗肿瘤作用及其分子机制仍有待阐明。本研究旨在通过 MTT 检测、流式细胞术、吖啶橙/溴化乙锭染色、透射电镜、细胞内活性氧（ROS）、超氧化物歧化酶（SOD）和丙二醛（MDA）测定以及 Western blot 等多种方法，研究紫杉醇对 CHMm 细胞的抗肿瘤作用及其相关信号转导通路。结果表明，紫杉醇呈剂量依赖性降低细胞活力，诱导 G2/M 期细胞周期阻滞，抑制细胞周期蛋白 B1 的表达，并诱导细胞凋亡。此外，紫杉醇上调 Bax 和细胞色素 c 的表达，降低凋亡调节因子 Bcl-2 的表达，导致 caspase-3 激活、染色质浓缩、核固缩、细胞内空泡化、ROS 和 MDA 生成增加以及 SOD 活性降低。然而，当 CHMm 细胞用 N-乙酰-L-半胱氨酸处理时，这些作用受到抑制。此外，紫杉醇处理抑制了磷酸化（p）-RAC-α丝氨酸/苏氨酸-蛋白激酶（AKT）和核糖体蛋白 S6 激酶 p-核糖体蛋白 S6 激酶蛋白的水平，并促进了丝裂原激活蛋白激酶（MAPK）和 p-90 kDa 核糖体蛋白 S6 激酶 1 蛋白在 CHMm 细胞中的磷酸化。结果表明，紫杉醇与 P38 和磷脂酰肌醇-4,5-二磷酸 3-激酶（PI3K）信号通路的药理学抑制剂（分别为 SB203580 和 LY294002）联合使用对 CHMm 细胞的增殖具有协同抑制作用。本研究结果表明，紫杉醇通过抑制 PI3K/AKT 信号通路和激活 MAPK 信号通路，增加内在凋亡，抑制 CHMm 细胞的肿瘤细胞增殖。
