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Pterostilbene exerts antitumor activity via the Notch1 signaling pathway in human lung adenocarcinoma cells.

Yang Y, Yan X, Duan W, Yan J, Yi W, Liang Z, Wang N, Li Y, Chen W, Yu S, Jin Z, Yi D - PLoS ONE (2013)

Bottom Line: PTE treatment resulted in a dose- and time-dependent decrease in the viability of A549 cells.DAPT (a gamma secretase inhibitor) and Notch1 siRNA prevented the induction of NICD and Hes1 activation by PTE treatment and sensitized the cells to PTE treatment.The down-regulation of Notch signaling also prevented the activation of pro-survival pathways (most notably the PI3K/Akt pathway) after PTE treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an City, China.

ABSTRACT
Although pterostilbene (PTE) has been shown to have potent antitumor activities against various cancer types, the molecular mechanisms of these activities remain unclear. In this study, we investigated the antitumor activity of PTE against human lung adenocarcinoma in vitro and in vivo and explored the role of the Notch1 signaling pathway in this process. PTE treatment resulted in a dose- and time-dependent decrease in the viability of A549 cells. Additionally, PTE exhibited strong antitumor activity, as evidenced not only by a reduced mitochondrial membrane potential (MMP) and a decreased intracellular glutathione content but also by increases in the apoptotic index and the level of reactive oxygen species (ROS). Furthermore, PTE treatment induced the activation of the Notch1 Intracellular Domain (NICD) protein and activated Hes1. DAPT (a gamma secretase inhibitor) and Notch1 siRNA prevented the induction of NICD and Hes1 activation by PTE treatment and sensitized the cells to PTE treatment. The down-regulation of Notch signaling also prevented the activation of pro-survival pathways (most notably the PI3K/Akt pathway) after PTE treatment. In summary, lung adenocarcinoma cells may enhance Notch1 activation as a protective mechanism in response to PTE treatment. Combining a gamma secretase inhibitor with PTE treatment may represent a novel approach for treating lung adenocarcinoma by inhibiting the survival pathways of cancer cells.

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The effects of PTE combined with Akt siRNA on the viability and Akt signaling of lung adenocarcinoma cells.(A) Cell viability was assessed using the MTT assay and was expressed as an OD value. (B) Representative Western blot results are shown. The results are expressed as the mean ± SEM, n = 6. **P<0.01 compared with the control siRNA group, ##P<0.01 compared with the PTE 6 µM group, $$P<0.01 compared with the Akt siRNA+PTE 6 µM group. PTE, pterostilbene; OD, optical density.
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pone-0062652-g008: The effects of PTE combined with Akt siRNA on the viability and Akt signaling of lung adenocarcinoma cells.(A) Cell viability was assessed using the MTT assay and was expressed as an OD value. (B) Representative Western blot results are shown. The results are expressed as the mean ± SEM, n = 6. **P<0.01 compared with the control siRNA group, ##P<0.01 compared with the PTE 6 µM group, $$P<0.01 compared with the Akt siRNA+PTE 6 µM group. PTE, pterostilbene; OD, optical density.

Mentions: The treatment of A549 cells with DAPT decreased the baseline levels of Cyclin D1 and survivin and suppressed the induction of Cyclin D1 and survivin by PTE (Figure 6). Because Notch1 may activate PI3K/Akt signaling to protect against DNA damage [17], the expression levels of proteins in this pathway were examined. In A549 cells, co-treatment with DAPT decreased the phosphorylation of Akt at Serine 473 induced by PTE and also mildly decreased the total Akt level (Figure 6). We then examined two targets of Akt, mTOR and the S6 ribosomal protein. The levels of S6 phosphorylated at Serine 235/236, mTOR phosphorylated at Serine 2448, total S6 and total mTOR were decreased following co-treatment with DAPT and PTE (Figure 6). Then, the expression of DNA-PK, a kinase that may activate Akt, was analyzed. We found that co-treatment with DAPT and PTE decreased the protein level of DNA-PK (Figure 6). Because functional Akt signaling may play a role in chemoresistance, we determined if the suppression of Akt with siRNA would alter the sensitization effect of PTE. Akt siRNA not only effectively reduced the levels of phosphorylated and total Akt protein (Figure 8B) but also decreased the viability (Figure 8A) of A549 cells following PTE treatment.


Pterostilbene exerts antitumor activity via the Notch1 signaling pathway in human lung adenocarcinoma cells.

Yang Y, Yan X, Duan W, Yan J, Yi W, Liang Z, Wang N, Li Y, Chen W, Yu S, Jin Z, Yi D - PLoS ONE (2013)

The effects of PTE combined with Akt siRNA on the viability and Akt signaling of lung adenocarcinoma cells.(A) Cell viability was assessed using the MTT assay and was expressed as an OD value. (B) Representative Western blot results are shown. The results are expressed as the mean ± SEM, n = 6. **P<0.01 compared with the control siRNA group, ##P<0.01 compared with the PTE 6 µM group, $$P<0.01 compared with the Akt siRNA+PTE 6 µM group. PTE, pterostilbene; OD, optical density.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3643961&req=5

pone-0062652-g008: The effects of PTE combined with Akt siRNA on the viability and Akt signaling of lung adenocarcinoma cells.(A) Cell viability was assessed using the MTT assay and was expressed as an OD value. (B) Representative Western blot results are shown. The results are expressed as the mean ± SEM, n = 6. **P<0.01 compared with the control siRNA group, ##P<0.01 compared with the PTE 6 µM group, $$P<0.01 compared with the Akt siRNA+PTE 6 µM group. PTE, pterostilbene; OD, optical density.
Mentions: The treatment of A549 cells with DAPT decreased the baseline levels of Cyclin D1 and survivin and suppressed the induction of Cyclin D1 and survivin by PTE (Figure 6). Because Notch1 may activate PI3K/Akt signaling to protect against DNA damage [17], the expression levels of proteins in this pathway were examined. In A549 cells, co-treatment with DAPT decreased the phosphorylation of Akt at Serine 473 induced by PTE and also mildly decreased the total Akt level (Figure 6). We then examined two targets of Akt, mTOR and the S6 ribosomal protein. The levels of S6 phosphorylated at Serine 235/236, mTOR phosphorylated at Serine 2448, total S6 and total mTOR were decreased following co-treatment with DAPT and PTE (Figure 6). Then, the expression of DNA-PK, a kinase that may activate Akt, was analyzed. We found that co-treatment with DAPT and PTE decreased the protein level of DNA-PK (Figure 6). Because functional Akt signaling may play a role in chemoresistance, we determined if the suppression of Akt with siRNA would alter the sensitization effect of PTE. Akt siRNA not only effectively reduced the levels of phosphorylated and total Akt protein (Figure 8B) but also decreased the viability (Figure 8A) of A549 cells following PTE treatment.

Bottom Line: PTE treatment resulted in a dose- and time-dependent decrease in the viability of A549 cells.DAPT (a gamma secretase inhibitor) and Notch1 siRNA prevented the induction of NICD and Hes1 activation by PTE treatment and sensitized the cells to PTE treatment.The down-regulation of Notch signaling also prevented the activation of pro-survival pathways (most notably the PI3K/Akt pathway) after PTE treatment.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an City, China.

ABSTRACT
Although pterostilbene (PTE) has been shown to have potent antitumor activities against various cancer types, the molecular mechanisms of these activities remain unclear. In this study, we investigated the antitumor activity of PTE against human lung adenocarcinoma in vitro and in vivo and explored the role of the Notch1 signaling pathway in this process. PTE treatment resulted in a dose- and time-dependent decrease in the viability of A549 cells. Additionally, PTE exhibited strong antitumor activity, as evidenced not only by a reduced mitochondrial membrane potential (MMP) and a decreased intracellular glutathione content but also by increases in the apoptotic index and the level of reactive oxygen species (ROS). Furthermore, PTE treatment induced the activation of the Notch1 Intracellular Domain (NICD) protein and activated Hes1. DAPT (a gamma secretase inhibitor) and Notch1 siRNA prevented the induction of NICD and Hes1 activation by PTE treatment and sensitized the cells to PTE treatment. The down-regulation of Notch signaling also prevented the activation of pro-survival pathways (most notably the PI3K/Akt pathway) after PTE treatment. In summary, lung adenocarcinoma cells may enhance Notch1 activation as a protective mechanism in response to PTE treatment. Combining a gamma secretase inhibitor with PTE treatment may represent a novel approach for treating lung adenocarcinoma by inhibiting the survival pathways of cancer cells.

Show MeSH
Related in: MedlinePlus