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Low amount of salinomycin greatly increases Akt activation, but reduces activated p70S6K levels.

Kim JH, Choi AR, Kim YK, Kim HS, Yoon S - Int J Mol Sci (2013)

Bottom Line: The results showed that Sal sensitization positively correlates with large reductions in p70S6K activation.In addition, the increased levels of pAkt were not reduced over the time course of the experiment.The results thereby suggest that Akt activation is increased in cells that survive Sal treatment and resist the cytotoxic effect of Sal.

View Article: PubMed Central - PubMed

Affiliation: Research Institute, National Cancer Center, Ilsan-gu, Goyang-si, Gyeonggi-do 410-769, Korea. jua@ncc.re.kr

ABSTRACT
The present study identified a novel salinomycin (Sal)-sensitization mechanism in cancer cells. We analyzed the signal proteins Akt, Jnk, p38, Jak, and Erk1/2 in cancer cell lines that had arrested growth following low amounts of Sal treatment. We also tested the signal molecules PI3K, PDK1, GSK3β, p70S6K, mTOR, and PTEN to analyze the PI3K/Akt/mTOR pathway. The results showed that Sal sensitization positively correlates with large reductions in p70S6K activation. Interestingly, Akt was the only signal protein to be significantly activated by Sal treatment. The Akt activation appeared to require the PI3K pathway as its activation was abolished by the PI3K inhibitors LY294002 and wortmannin. The Akt activation by Sal was conserved in the other cell lines analyzed, which originated from other organs. Both Akt activation and C-PARP production were proportionally increased with increased doses of Sal. In addition, the increased levels of pAkt were not reduced over the time course of the experiment. Co-treatment with Akt inhibitors sensitized the Sal-treated cancer cells. The results thereby suggest that Akt activation is increased in cells that survive Sal treatment and resist the cytotoxic effect of Sal. Taken together; these results indicate that Akt activation may promote the resistance of cancer cells to Sal.

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Related in: MedlinePlus

Low concentration of Sal highly activates Akt. Hs578T cell extracts were collected at (A) 12 h and (B) 24 h after treatment with 0.5 μM Sal or from Dimethylsulfoxide (DMSO)-treated samples (Con). Western blot analyses were performed using antibodies against pJnk1, pAkt, Akt, PI3K, Jnk1, pp38, p38, pJak2, Jak2, pErk1/2, Erk1/2, pIKKα/β, Jak1, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH).
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f1-ijms-14-17304: Low concentration of Sal highly activates Akt. Hs578T cell extracts were collected at (A) 12 h and (B) 24 h after treatment with 0.5 μM Sal or from Dimethylsulfoxide (DMSO)-treated samples (Con). Western blot analyses were performed using antibodies against pJnk1, pAkt, Akt, PI3K, Jnk1, pp38, p38, pJak2, Jak2, pErk1/2, Erk1/2, pIKKα/β, Jak1, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH).

Mentions: As shown in Figure 1, Sal treatment did not alter the total levels of these proteins at 12 h and 24 h. We then observed and analyzed active forms of these signal proteins. We found that Akt activation occurred at the earlier time point (12 h) and was increased at the later time point (24 h). Phosphorylated Jnk1, p38, Erk1/2, IKKα/β, and Jak2 were detected in the control cells at 12 h or 24 h, but these levels showed negligible changes and were unaffected by Sal treatment (Figure 1). Phosphorylated forms of PI3K, c-Src, and Jak1 were not detected in the control or Sal-treated cells (data not shown). Taken together, we found that only Akt was significantly activated at both 12 h and 24 h, thereby indicating that the inhibition of cellular proliferation by Sal positively correlates with increased Akt activation.


Low amount of salinomycin greatly increases Akt activation, but reduces activated p70S6K levels.

Kim JH, Choi AR, Kim YK, Kim HS, Yoon S - Int J Mol Sci (2013)

Low concentration of Sal highly activates Akt. Hs578T cell extracts were collected at (A) 12 h and (B) 24 h after treatment with 0.5 μM Sal or from Dimethylsulfoxide (DMSO)-treated samples (Con). Western blot analyses were performed using antibodies against pJnk1, pAkt, Akt, PI3K, Jnk1, pp38, p38, pJak2, Jak2, pErk1/2, Erk1/2, pIKKα/β, Jak1, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3794729&req=5

f1-ijms-14-17304: Low concentration of Sal highly activates Akt. Hs578T cell extracts were collected at (A) 12 h and (B) 24 h after treatment with 0.5 μM Sal or from Dimethylsulfoxide (DMSO)-treated samples (Con). Western blot analyses were performed using antibodies against pJnk1, pAkt, Akt, PI3K, Jnk1, pp38, p38, pJak2, Jak2, pErk1/2, Erk1/2, pIKKα/β, Jak1, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH).
Mentions: As shown in Figure 1, Sal treatment did not alter the total levels of these proteins at 12 h and 24 h. We then observed and analyzed active forms of these signal proteins. We found that Akt activation occurred at the earlier time point (12 h) and was increased at the later time point (24 h). Phosphorylated Jnk1, p38, Erk1/2, IKKα/β, and Jak2 were detected in the control cells at 12 h or 24 h, but these levels showed negligible changes and were unaffected by Sal treatment (Figure 1). Phosphorylated forms of PI3K, c-Src, and Jak1 were not detected in the control or Sal-treated cells (data not shown). Taken together, we found that only Akt was significantly activated at both 12 h and 24 h, thereby indicating that the inhibition of cellular proliferation by Sal positively correlates with increased Akt activation.

Bottom Line: The results showed that Sal sensitization positively correlates with large reductions in p70S6K activation.In addition, the increased levels of pAkt were not reduced over the time course of the experiment.The results thereby suggest that Akt activation is increased in cells that survive Sal treatment and resist the cytotoxic effect of Sal.

View Article: PubMed Central - PubMed

Affiliation: Research Institute, National Cancer Center, Ilsan-gu, Goyang-si, Gyeonggi-do 410-769, Korea. jua@ncc.re.kr

ABSTRACT
The present study identified a novel salinomycin (Sal)-sensitization mechanism in cancer cells. We analyzed the signal proteins Akt, Jnk, p38, Jak, and Erk1/2 in cancer cell lines that had arrested growth following low amounts of Sal treatment. We also tested the signal molecules PI3K, PDK1, GSK3β, p70S6K, mTOR, and PTEN to analyze the PI3K/Akt/mTOR pathway. The results showed that Sal sensitization positively correlates with large reductions in p70S6K activation. Interestingly, Akt was the only signal protein to be significantly activated by Sal treatment. The Akt activation appeared to require the PI3K pathway as its activation was abolished by the PI3K inhibitors LY294002 and wortmannin. The Akt activation by Sal was conserved in the other cell lines analyzed, which originated from other organs. Both Akt activation and C-PARP production were proportionally increased with increased doses of Sal. In addition, the increased levels of pAkt were not reduced over the time course of the experiment. Co-treatment with Akt inhibitors sensitized the Sal-treated cancer cells. The results thereby suggest that Akt activation is increased in cells that survive Sal treatment and resist the cytotoxic effect of Sal. Taken together; these results indicate that Akt activation may promote the resistance of cancer cells to Sal.

Show MeSH
Related in: MedlinePlus