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Regulation of the cell cycle and PI3K/Akt/mTOR signaling pathway by tanshinone I in human breast cancer cell lines.

Wang L, Wu J, Lu J, Ma R, Sun D, Tang J - Mol Med Rep (2014)

Bottom Line: Tan I exerted similar antiproliferative activities and induction of apoptosis, resulting in S phase arrest accompanied by decreases in cyclin B and increases in cyclin E and cyclin A proteins, which may have been associated with the upregulation of cyclin‑dependent kinase inhibitors p21Cip1 and p27Kip1.In addition, Tan I was found to downregulate anti‑apoptotic and upregulate associated apoptotic components of the PI3K/Akt/mTOR signaling pathway.These results clearly indicated that the mechanism of action of Tan I involved, at least partially, an effect on the PI3K/Akt/mTOR signaling pathway, providing new information for anticancer drug design and development.

View Article: PubMed Central - PubMed

Affiliation: First Clinical Medical College, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210046, P.R. China.

ABSTRACT
Breast cancer is the second leading cause of cancer‑related mortality in females worldwide. Therefore, identifying alternative strategies to combat the disease mortality is important. The aim of the present study was to investigate the effect of tanshinone I (Tan I) on the tumorigenicity of estrogen‑responsive MCF‑7 and estrogen‑independent MDA‑MB‑453 human breast cancer cells. The cytotoxicity of Tan I was evaluated using a Cell Counting Kit‑8 assay, the apoptosis and cell cycle distribution were detected using flow cytometry and the cell morphology was observed using a fluorescence microscope. In addition, the cell cycle regulatory proteins and apoptosis‑associated proteins involved in the phosphatidylinositide 3‑kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway were detected using western blot analysis using specific protein antibodies. The MCF‑7 and MDA‑MB‑453 cells were equally sensitive to Tan I regardless of their responsiveness to estrogen. Tan I exerted similar antiproliferative activities and induction of apoptosis, resulting in S phase arrest accompanied by decreases in cyclin B and increases in cyclin E and cyclin A proteins, which may have been associated with the upregulation of cyclin‑dependent kinase inhibitors p21Cip1 and p27Kip1. In addition, Tan I was found to downregulate anti‑apoptotic and upregulate associated apoptotic components of the PI3K/Akt/mTOR signaling pathway. Notably, treatment with the PI3K inhibitor, LY294002, decreased the levels of phosphorylated (p)‑PI3K, p‑Akt and p‑mTOR. These results clearly indicated that the mechanism of action of Tan I involved, at least partially, an effect on the PI3K/Akt/mTOR signaling pathway, providing new information for anticancer drug design and development.

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Apoptosis-associated proteins in breast cancer cells treated with Tan I for 48 h and observed by western blot analysis. Tanshinone I, Tan I; PI3K, phosphatidylinositide 3-kinase; p-, phosphorylated; Akt, protein kinase B; mTOR, mammalian target of rapamycin; Bad, Bcl-2-associated death promoter.
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f7-mmr-11-02-0931: Apoptosis-associated proteins in breast cancer cells treated with Tan I for 48 h and observed by western blot analysis. Tanshinone I, Tan I; PI3K, phosphatidylinositide 3-kinase; p-, phosphorylated; Akt, protein kinase B; mTOR, mammalian target of rapamycin; Bad, Bcl-2-associated death promoter.

Mentions: The present study then examined the possibility that the induction of apoptosis in breast cancer cells by Tan I involved suppression of PI3K/Akt/mTOR signaling. The effects of Tan I on the expression of Akt and of specific downstream components of the Akt pathway, including PI3K, p-PI3K, Akt (inactive), p-Akt, mTOR (inactive) and p-mTOR, were evaluated using phosphorylated antibodies specific to PI3K, Akt and mTOR in immunoblotting. The various forms of cytochrome c, caspase-9 and caspase-3 in breast cancer cells were also examined. Computer-assisted image analysis demonstrated a clear dose-dependent reduction in the phosphorylation of Akt at Thr 308 and PI3K in response to treatment of the MCF-1 and MDA-MB-453 cells with Tan I, whereas the levels of total Akt and PI3K were unaffected by Tan I under the same conditions (Fig. 7). Marked increases in the dephosphorylated form of mTOR were also observed in the MCF-7 and MDA-MB-453 breast cancer cells in a dose-dependent manner at 48 h. These data demonstrated that Tan I-induced growth inhibition may be mediated by the inactivation of PI3K/Akt activity in breast cancer cells. In addition, marked increases in the levels of the Bad, cytochrome c, caspase-9 and caspase-3 proteins were observed in the MCF-7 and MDA-MB-453 cells treated with Tan I, compared with the control group (P<0.05; Fig. 7), and this upregulation occurred in a dose-dependent manner. Taken together, these results suggested that the mitochondrial apoptotic pathway is involved in Tan I-induced apoptosis, which may be involved the PI3K/Akt/mTOR signaling pathway.


Regulation of the cell cycle and PI3K/Akt/mTOR signaling pathway by tanshinone I in human breast cancer cell lines.

Wang L, Wu J, Lu J, Ma R, Sun D, Tang J - Mol Med Rep (2014)

Apoptosis-associated proteins in breast cancer cells treated with Tan I for 48 h and observed by western blot analysis. Tanshinone I, Tan I; PI3K, phosphatidylinositide 3-kinase; p-, phosphorylated; Akt, protein kinase B; mTOR, mammalian target of rapamycin; Bad, Bcl-2-associated death promoter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4262478&req=5

f7-mmr-11-02-0931: Apoptosis-associated proteins in breast cancer cells treated with Tan I for 48 h and observed by western blot analysis. Tanshinone I, Tan I; PI3K, phosphatidylinositide 3-kinase; p-, phosphorylated; Akt, protein kinase B; mTOR, mammalian target of rapamycin; Bad, Bcl-2-associated death promoter.
Mentions: The present study then examined the possibility that the induction of apoptosis in breast cancer cells by Tan I involved suppression of PI3K/Akt/mTOR signaling. The effects of Tan I on the expression of Akt and of specific downstream components of the Akt pathway, including PI3K, p-PI3K, Akt (inactive), p-Akt, mTOR (inactive) and p-mTOR, were evaluated using phosphorylated antibodies specific to PI3K, Akt and mTOR in immunoblotting. The various forms of cytochrome c, caspase-9 and caspase-3 in breast cancer cells were also examined. Computer-assisted image analysis demonstrated a clear dose-dependent reduction in the phosphorylation of Akt at Thr 308 and PI3K in response to treatment of the MCF-1 and MDA-MB-453 cells with Tan I, whereas the levels of total Akt and PI3K were unaffected by Tan I under the same conditions (Fig. 7). Marked increases in the dephosphorylated form of mTOR were also observed in the MCF-7 and MDA-MB-453 breast cancer cells in a dose-dependent manner at 48 h. These data demonstrated that Tan I-induced growth inhibition may be mediated by the inactivation of PI3K/Akt activity in breast cancer cells. In addition, marked increases in the levels of the Bad, cytochrome c, caspase-9 and caspase-3 proteins were observed in the MCF-7 and MDA-MB-453 cells treated with Tan I, compared with the control group (P<0.05; Fig. 7), and this upregulation occurred in a dose-dependent manner. Taken together, these results suggested that the mitochondrial apoptotic pathway is involved in Tan I-induced apoptosis, which may be involved the PI3K/Akt/mTOR signaling pathway.

Bottom Line: Tan I exerted similar antiproliferative activities and induction of apoptosis, resulting in S phase arrest accompanied by decreases in cyclin B and increases in cyclin E and cyclin A proteins, which may have been associated with the upregulation of cyclin‑dependent kinase inhibitors p21Cip1 and p27Kip1.In addition, Tan I was found to downregulate anti‑apoptotic and upregulate associated apoptotic components of the PI3K/Akt/mTOR signaling pathway.These results clearly indicated that the mechanism of action of Tan I involved, at least partially, an effect on the PI3K/Akt/mTOR signaling pathway, providing new information for anticancer drug design and development.

View Article: PubMed Central - PubMed

Affiliation: First Clinical Medical College, Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210046, P.R. China.

ABSTRACT
Breast cancer is the second leading cause of cancer‑related mortality in females worldwide. Therefore, identifying alternative strategies to combat the disease mortality is important. The aim of the present study was to investigate the effect of tanshinone I (Tan I) on the tumorigenicity of estrogen‑responsive MCF‑7 and estrogen‑independent MDA‑MB‑453 human breast cancer cells. The cytotoxicity of Tan I was evaluated using a Cell Counting Kit‑8 assay, the apoptosis and cell cycle distribution were detected using flow cytometry and the cell morphology was observed using a fluorescence microscope. In addition, the cell cycle regulatory proteins and apoptosis‑associated proteins involved in the phosphatidylinositide 3‑kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway were detected using western blot analysis using specific protein antibodies. The MCF‑7 and MDA‑MB‑453 cells were equally sensitive to Tan I regardless of their responsiveness to estrogen. Tan I exerted similar antiproliferative activities and induction of apoptosis, resulting in S phase arrest accompanied by decreases in cyclin B and increases in cyclin E and cyclin A proteins, which may have been associated with the upregulation of cyclin‑dependent kinase inhibitors p21Cip1 and p27Kip1. In addition, Tan I was found to downregulate anti‑apoptotic and upregulate associated apoptotic components of the PI3K/Akt/mTOR signaling pathway. Notably, treatment with the PI3K inhibitor, LY294002, decreased the levels of phosphorylated (p)‑PI3K, p‑Akt and p‑mTOR. These results clearly indicated that the mechanism of action of Tan I involved, at least partially, an effect on the PI3K/Akt/mTOR signaling pathway, providing new information for anticancer drug design and development.

Show MeSH
Related in: MedlinePlus