Paclitaxel suppresses proliferation and induces apoptosis through regulation of ROS and the AKT/MAPK signaling pathway in canine mammary gland tumor cells

Abstract

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.

Fabrication of Polylactic Acid/Paclitaxel Nano Fibers by Electrospinning for Cancer Therapeutics

“…For example, the optical density ratio is around 0.12 for the concentration of paclitaxel at 200 nM. This concentration marks the upper bond of a low concentration of paclitaxel for anticancer effects as reported in the literature [38][39][40][41][42]. In Fig.…”

“…In our cases, the released paclitaxel concentration is estimated at around 32 -68 nM (see Appendix) for the optical density ratio of 0.26 and 0.19 respectively. It could be concluded that the anticancer effect is attributed to the lower concentration of paclitaxel, which would have a direct impact on the microtubules of HCT-116, e.g., increased di culty in passing thought the S1 checkpoint but not the overall mitosis [38][39][40][41][42].…”

<p>Improving the anti-keloid outcomes through liposomes loading paclitaxel&ndash;cholesterol complexes</p>

“…44 Previous studies demonstrated that the activation of PI3K/AKT signaling contributed to apoptosis in cancer cells induced by PTX. 45 Therefore, we studied the anti-inflammatory and antifibrotic effects of PTX in keloids by inhibiting the AKT/ GSK3β signaling. HKFs was treated by PTX (0.1 µg/mL) and using LY294002 (5 µM) as a positive control, then Western blot was performed to detect the expression of AKT/GSK3β signaling and the production of α-SMA and collagen I, which were markers in fibrotic remodeling.…”

Divaricoside Exerts Antitumor Effects, in Part, by Modulating Mcl-1 in Human Oral Squamous Cell Carcinoma Cells

“…Dysregulation of oxidative stress-related genes and betel quid chewing have been strongly associated with the malignant transformation in the oral cavity [ 43 , 44 ]. However, ROS production also represents an important mechanism of action of chemotherapeutic agents against cancer [ 45 ]. For example, paclitaxel suppresses cell proliferation and induces apoptosis by increasing ROS generation in canine mammary gland tumor cells [ 45 ].…”

“…However, ROS production also represents an important mechanism of action of chemotherapeutic agents against cancer [ 45 ]. For example, paclitaxel suppresses cell proliferation and induces apoptosis by increasing ROS generation in canine mammary gland tumor cells [ 45 ]. Bufalin has also been shown to induce apoptosis via reduction in ROS production in tongue cancer cells [ 46 ].…”