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δ-Tocotrienol oxazine derivative antagonizes mammary tumor cell compensatory response to CoCl2-induced hypoxia.

Ananthula S, Parajuli P, Behery FA, Alayoubi AY, Nazzal S, El Sayed K, Sylvester PW - Biomed Res Int (2014)

Bottom Line: In response to low oxygen supply, cancer cells elevate production of HIF-1α, a hypoxia-inducible transcription factor that subsequently acts to stimulate blood vessel formation and promote survival.Treatment with 150 µM CoCl2 induced a hypoxic response in +SA mammary tumor cells as evidenced by a large increase in HIF-1α levels, and combined treatment with compound 44 attenuated this response.Additional in vivo studies showed that intralesional treatment with compound 44 in BALB/c mice bearing +SA mammary tumors significantly decreased the levels of HIF-1α, and this effect was associated with a corresponding decrease in Akt/mTOR signaling and activation of downstream targets p70S6 kinase and eIF-4E1.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmacy, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209-0470, USA.

ABSTRACT
In response to low oxygen supply, cancer cells elevate production of HIF-1α, a hypoxia-inducible transcription factor that subsequently acts to stimulate blood vessel formation and promote survival. Studies were conducted to determine the role of δ-tocotrienol and a semisynthetic δ-tocotrienol oxazine derivative, compound 44, on +SA mammary tumor cell hypoxic response. Treatment with 150 µM CoCl2 induced a hypoxic response in +SA mammary tumor cells as evidenced by a large increase in HIF-1α levels, and combined treatment with compound 44 attenuated this response. CoCl2-induced hypoxia was also associated with a large increase in Akt/mTOR signaling, activation of downstream targets p70S6K and eIF-4E1, and a significant increase in VEGF production, and combined treatment with compound 44 blocked this response. Additional in vivo studies showed that intralesional treatment with compound 44 in BALB/c mice bearing +SA mammary tumors significantly decreased the levels of HIF-1α, and this effect was associated with a corresponding decrease in Akt/mTOR signaling and activation of downstream targets p70S6 kinase and eIF-4E1. These findings demonstrate that treatment with the δ-tocotrienol oxazine derivative, compound 44, significantly attenuates +SA mammary tumor cell compensatory responses to hypoxia and suggests that this compound may provide benefit in the treatment of rapidly growing solid breast tumors.

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(a) Dose-response and (b) time-response effect of CoCl2 on HIF-1α levels in +SA mammary cancer cells grown in culture. +SA cells were seeded at concentration of 1.5 × 106 in 100 mm culture dishes and allowed to attach overnight. The following day, cells were divided into treatment groups and exposed to various concentrations of CoCl2 for 0–24 hr incubation period. Afterwards, cells were isolated with trypsin, and whole cell lysates were prepared for Western blot analysis. Scanning densitometric analysis was performed on all blots done in triplicate and the integrated optical density of each band was normalized with corresponding α-tubulin, as shown in the bar graphs below their respective Western blot image. Vertical bars indicate the normalized integrated optical density of bands visualized in each lane ± SEM. *P < 0.05 as compared to the vehicle-treated controls.
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fig3: (a) Dose-response and (b) time-response effect of CoCl2 on HIF-1α levels in +SA mammary cancer cells grown in culture. +SA cells were seeded at concentration of 1.5 × 106 in 100 mm culture dishes and allowed to attach overnight. The following day, cells were divided into treatment groups and exposed to various concentrations of CoCl2 for 0–24 hr incubation period. Afterwards, cells were isolated with trypsin, and whole cell lysates were prepared for Western blot analysis. Scanning densitometric analysis was performed on all blots done in triplicate and the integrated optical density of each band was normalized with corresponding α-tubulin, as shown in the bar graphs below their respective Western blot image. Vertical bars indicate the normalized integrated optical density of bands visualized in each lane ± SEM. *P < 0.05 as compared to the vehicle-treated controls.

Mentions: Dose- and time-dependent studies were conducted to determine the effects of CoCl2 treatment on HIF-1α levels in +SA mammary tumor cells. Treatment with 0–150 µM CoCl2 resulted in a dose-responsive increase in HIF-1α levels after a 24 hr incubation period, whereas treatment with 200 µM CoCl2 attenuated this response (Figure 3(a)). Based on these findings and the results in Figure 2(a) that showed treatment with 200–300 µM CoCl2 decreased +SA cell viability, a treatment dose of 150 µM CoCl2 was chosen for subsequent experimentation because this dose induced a robust hypoxic response, as indicated by a large increase in HIFα-1 levels, without causing cytotoxic effects on +SA tumor cells growth or viability (Figure 3(a)). Treatment with 150 µM CoCl2 displayed a time-responsive increase in HIF-1α levels that peaked at 24 hr after the initiation of treatment (Figure 3(b)).


δ-Tocotrienol oxazine derivative antagonizes mammary tumor cell compensatory response to CoCl2-induced hypoxia.

Ananthula S, Parajuli P, Behery FA, Alayoubi AY, Nazzal S, El Sayed K, Sylvester PW - Biomed Res Int (2014)

(a) Dose-response and (b) time-response effect of CoCl2 on HIF-1α levels in +SA mammary cancer cells grown in culture. +SA cells were seeded at concentration of 1.5 × 106 in 100 mm culture dishes and allowed to attach overnight. The following day, cells were divided into treatment groups and exposed to various concentrations of CoCl2 for 0–24 hr incubation period. Afterwards, cells were isolated with trypsin, and whole cell lysates were prepared for Western blot analysis. Scanning densitometric analysis was performed on all blots done in triplicate and the integrated optical density of each band was normalized with corresponding α-tubulin, as shown in the bar graphs below their respective Western blot image. Vertical bars indicate the normalized integrated optical density of bands visualized in each lane ± SEM. *P < 0.05 as compared to the vehicle-treated controls.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129965&req=5

fig3: (a) Dose-response and (b) time-response effect of CoCl2 on HIF-1α levels in +SA mammary cancer cells grown in culture. +SA cells were seeded at concentration of 1.5 × 106 in 100 mm culture dishes and allowed to attach overnight. The following day, cells were divided into treatment groups and exposed to various concentrations of CoCl2 for 0–24 hr incubation period. Afterwards, cells were isolated with trypsin, and whole cell lysates were prepared for Western blot analysis. Scanning densitometric analysis was performed on all blots done in triplicate and the integrated optical density of each band was normalized with corresponding α-tubulin, as shown in the bar graphs below their respective Western blot image. Vertical bars indicate the normalized integrated optical density of bands visualized in each lane ± SEM. *P < 0.05 as compared to the vehicle-treated controls.
Mentions: Dose- and time-dependent studies were conducted to determine the effects of CoCl2 treatment on HIF-1α levels in +SA mammary tumor cells. Treatment with 0–150 µM CoCl2 resulted in a dose-responsive increase in HIF-1α levels after a 24 hr incubation period, whereas treatment with 200 µM CoCl2 attenuated this response (Figure 3(a)). Based on these findings and the results in Figure 2(a) that showed treatment with 200–300 µM CoCl2 decreased +SA cell viability, a treatment dose of 150 µM CoCl2 was chosen for subsequent experimentation because this dose induced a robust hypoxic response, as indicated by a large increase in HIFα-1 levels, without causing cytotoxic effects on +SA tumor cells growth or viability (Figure 3(a)). Treatment with 150 µM CoCl2 displayed a time-responsive increase in HIF-1α levels that peaked at 24 hr after the initiation of treatment (Figure 3(b)).

Bottom Line: In response to low oxygen supply, cancer cells elevate production of HIF-1α, a hypoxia-inducible transcription factor that subsequently acts to stimulate blood vessel formation and promote survival.Treatment with 150 µM CoCl2 induced a hypoxic response in +SA mammary tumor cells as evidenced by a large increase in HIF-1α levels, and combined treatment with compound 44 attenuated this response.Additional in vivo studies showed that intralesional treatment with compound 44 in BALB/c mice bearing +SA mammary tumors significantly decreased the levels of HIF-1α, and this effect was associated with a corresponding decrease in Akt/mTOR signaling and activation of downstream targets p70S6 kinase and eIF-4E1.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmacy, University of Louisiana at Monroe, 700 University Avenue, Monroe, LA 71209-0470, USA.

ABSTRACT
In response to low oxygen supply, cancer cells elevate production of HIF-1α, a hypoxia-inducible transcription factor that subsequently acts to stimulate blood vessel formation and promote survival. Studies were conducted to determine the role of δ-tocotrienol and a semisynthetic δ-tocotrienol oxazine derivative, compound 44, on +SA mammary tumor cell hypoxic response. Treatment with 150 µM CoCl2 induced a hypoxic response in +SA mammary tumor cells as evidenced by a large increase in HIF-1α levels, and combined treatment with compound 44 attenuated this response. CoCl2-induced hypoxia was also associated with a large increase in Akt/mTOR signaling, activation of downstream targets p70S6K and eIF-4E1, and a significant increase in VEGF production, and combined treatment with compound 44 blocked this response. Additional in vivo studies showed that intralesional treatment with compound 44 in BALB/c mice bearing +SA mammary tumors significantly decreased the levels of HIF-1α, and this effect was associated with a corresponding decrease in Akt/mTOR signaling and activation of downstream targets p70S6 kinase and eIF-4E1. These findings demonstrate that treatment with the δ-tocotrienol oxazine derivative, compound 44, significantly attenuates +SA mammary tumor cell compensatory responses to hypoxia and suggests that this compound may provide benefit in the treatment of rapidly growing solid breast tumors.

Show MeSH
Related in: MedlinePlus