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Bitter melon juice targets molecular mechanisms underlying gemcitabine resistance in pancreatic cancer cells.

Somasagara RR, Deep G, Shrotriya S, Patel M, Agarwal C, Agarwal R - Int. J. Oncol. (2015)

Bottom Line: GR PanC cells showed distinct morphological features including spindle-shaped morphology and a decrease in E-cadherin expression.Importantly, GR cells showed a significant increase in Akt and ERK1/2 phosphorylation and their inhibition decreased cell viability, suggesting their role in survival and drug resistance of these cells.Recently, we reported strong efficacy of BMJ against a panel of GS cells in culture and nude mice, which we expanded here and found that BMJ was also effective in decreasing both Akt and ERK1/2 phosphorylation and viability of GR PanC cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.

ABSTRACT
Pancreatic cancer (PanC) is one of the most lethal malignancies, and resistance towards gemcitabine, the front-line chemotherapy, is the main cause for dismal rate of survival in PanC patients; overcoming this resistance remains a major challenge to treat this deadly malignancy. Whereas several molecular mechanisms are known for gemcitabine resistance in PanC cells, altered metabolism and bioenergetics are not yet studied. Here, we compared metabolic and bioenergetic functions between gemcitabine-resistant (GR) and gemcitabine-sensitive (GS) PanC cells and underlying molecular mechanisms, together with efficacy of a natural agent bitter melon juice (BMJ). GR PanC cells showed distinct morphological features including spindle-shaped morphology and a decrease in E-cadherin expression. GR cells also showed higher ATP production with an increase in oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Molecular studies showed higher expression of glucose transporters (GLUT1 and 4) suggesting an increase in glucose uptake by GR cells. Importantly, GR cells showed a significant increase in Akt and ERK1/2 phosphorylation and their inhibition decreased cell viability, suggesting their role in survival and drug resistance of these cells. Recently, we reported strong efficacy of BMJ against a panel of GS cells in culture and nude mice, which we expanded here and found that BMJ was also effective in decreasing both Akt and ERK1/2 phosphorylation and viability of GR PanC cells. Overall, we have identified novel mechanisms of gemcitabine resistance in PanC cells which are targeted by BMJ. Considering the short survival in PanC patients, our findings could have high translational potential in controlling this deadly malignancy.

No MeSH data available.


Related in: MedlinePlus

The combination of Akt inhibitor MK-2206 and MEK inhibitor PD98059 induces cell death in gemcitabine-resistant (GR) AsPC-1 cells. (A and B) GR AsPC-1 cells were treated with MK-2206 and/or PD98059 and analyzed for total cell number and percentage of dead cells by trypan blue assay, and for percentage of apoptotic cell death by Annexin V/propidium iodide (PI) staining following the procedures detailed in Materials and methods. *P≤0.001, #p≤0.01 and $p≤0.05. (C) GR AsPC-1 cells were treated with MK-2206 and PD98059 and analyzed for phosphorylated and total ERK1/2 and Akt.
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f4-ijo-46-04-1849: The combination of Akt inhibitor MK-2206 and MEK inhibitor PD98059 induces cell death in gemcitabine-resistant (GR) AsPC-1 cells. (A and B) GR AsPC-1 cells were treated with MK-2206 and/or PD98059 and analyzed for total cell number and percentage of dead cells by trypan blue assay, and for percentage of apoptotic cell death by Annexin V/propidium iodide (PI) staining following the procedures detailed in Materials and methods. *P≤0.001, #p≤0.01 and $p≤0.05. (C) GR AsPC-1 cells were treated with MK-2206 and PD98059 and analyzed for phosphorylated and total ERK1/2 and Akt.

Mentions: Since we did not observe a strong growth inhibitory and cell death effect of Akt inhibitor even though the Akt phosphorylation was completely inhibited by MK-2206 at 100 nM concentration (Fig. 3), we next assessed the involvement of both Akt and MEK-ERK1/2 pathways in regulating apoptosis in GR AsPC-1 cells, by employing both Akt and MEK inhibitors MK-2206 and PD98059, respectively, alone and in combination. As shown in Fig. 4A, in general, compared to each inhibitor alone, their combination resulted in a stronger cell growth inhibition and cell death in GR AsPC-1 cells. Similar observation was also evident in apoptotic cell death following MK-2206 and PD98059 treatment of GR AsPC-1 cells and a combination was better than either agent alone (Fig. 4B). Western blotting showed that indeed both ERK1/2 and Akt are strongly phosphorylated in GR AsPC-1 cells, and that treatment with MK-2206 and PD98059 reduces the phosphorylation of Akt and ERK1/2, respectively (Fig. 4C). Importantly, the combination of MK-2206 and PD98059 caused a maximum inhibition of Akt phosphorylation; however, no additional decrease in ERK1/2 phosphorylation was observed in combination compared with PD98059 alone (Fig. 4C).


Bitter melon juice targets molecular mechanisms underlying gemcitabine resistance in pancreatic cancer cells.

Somasagara RR, Deep G, Shrotriya S, Patel M, Agarwal C, Agarwal R - Int. J. Oncol. (2015)

The combination of Akt inhibitor MK-2206 and MEK inhibitor PD98059 induces cell death in gemcitabine-resistant (GR) AsPC-1 cells. (A and B) GR AsPC-1 cells were treated with MK-2206 and/or PD98059 and analyzed for total cell number and percentage of dead cells by trypan blue assay, and for percentage of apoptotic cell death by Annexin V/propidium iodide (PI) staining following the procedures detailed in Materials and methods. *P≤0.001, #p≤0.01 and $p≤0.05. (C) GR AsPC-1 cells were treated with MK-2206 and PD98059 and analyzed for phosphorylated and total ERK1/2 and Akt.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4356502&req=5

f4-ijo-46-04-1849: The combination of Akt inhibitor MK-2206 and MEK inhibitor PD98059 induces cell death in gemcitabine-resistant (GR) AsPC-1 cells. (A and B) GR AsPC-1 cells were treated with MK-2206 and/or PD98059 and analyzed for total cell number and percentage of dead cells by trypan blue assay, and for percentage of apoptotic cell death by Annexin V/propidium iodide (PI) staining following the procedures detailed in Materials and methods. *P≤0.001, #p≤0.01 and $p≤0.05. (C) GR AsPC-1 cells were treated with MK-2206 and PD98059 and analyzed for phosphorylated and total ERK1/2 and Akt.
Mentions: Since we did not observe a strong growth inhibitory and cell death effect of Akt inhibitor even though the Akt phosphorylation was completely inhibited by MK-2206 at 100 nM concentration (Fig. 3), we next assessed the involvement of both Akt and MEK-ERK1/2 pathways in regulating apoptosis in GR AsPC-1 cells, by employing both Akt and MEK inhibitors MK-2206 and PD98059, respectively, alone and in combination. As shown in Fig. 4A, in general, compared to each inhibitor alone, their combination resulted in a stronger cell growth inhibition and cell death in GR AsPC-1 cells. Similar observation was also evident in apoptotic cell death following MK-2206 and PD98059 treatment of GR AsPC-1 cells and a combination was better than either agent alone (Fig. 4B). Western blotting showed that indeed both ERK1/2 and Akt are strongly phosphorylated in GR AsPC-1 cells, and that treatment with MK-2206 and PD98059 reduces the phosphorylation of Akt and ERK1/2, respectively (Fig. 4C). Importantly, the combination of MK-2206 and PD98059 caused a maximum inhibition of Akt phosphorylation; however, no additional decrease in ERK1/2 phosphorylation was observed in combination compared with PD98059 alone (Fig. 4C).

Bottom Line: GR PanC cells showed distinct morphological features including spindle-shaped morphology and a decrease in E-cadherin expression.Importantly, GR cells showed a significant increase in Akt and ERK1/2 phosphorylation and their inhibition decreased cell viability, suggesting their role in survival and drug resistance of these cells.Recently, we reported strong efficacy of BMJ against a panel of GS cells in culture and nude mice, which we expanded here and found that BMJ was also effective in decreasing both Akt and ERK1/2 phosphorylation and viability of GR PanC cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.

ABSTRACT
Pancreatic cancer (PanC) is one of the most lethal malignancies, and resistance towards gemcitabine, the front-line chemotherapy, is the main cause for dismal rate of survival in PanC patients; overcoming this resistance remains a major challenge to treat this deadly malignancy. Whereas several molecular mechanisms are known for gemcitabine resistance in PanC cells, altered metabolism and bioenergetics are not yet studied. Here, we compared metabolic and bioenergetic functions between gemcitabine-resistant (GR) and gemcitabine-sensitive (GS) PanC cells and underlying molecular mechanisms, together with efficacy of a natural agent bitter melon juice (BMJ). GR PanC cells showed distinct morphological features including spindle-shaped morphology and a decrease in E-cadherin expression. GR cells also showed higher ATP production with an increase in oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Molecular studies showed higher expression of glucose transporters (GLUT1 and 4) suggesting an increase in glucose uptake by GR cells. Importantly, GR cells showed a significant increase in Akt and ERK1/2 phosphorylation and their inhibition decreased cell viability, suggesting their role in survival and drug resistance of these cells. Recently, we reported strong efficacy of BMJ against a panel of GS cells in culture and nude mice, which we expanded here and found that BMJ was also effective in decreasing both Akt and ERK1/2 phosphorylation and viability of GR PanC cells. Overall, we have identified novel mechanisms of gemcitabine resistance in PanC cells which are targeted by BMJ. Considering the short survival in PanC patients, our findings could have high translational potential in controlling this deadly malignancy.

No MeSH data available.


Related in: MedlinePlus