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Anti-proliferative activity of oral anti-hyperglycemic agents on human vascular smooth muscle cells: thiazolidinediones (glitazones) have enhanced activity under high glucose conditions.

Little PJ, Osman N, de Dios ST, Cemerlang N, Ballinger M, Nigro J - Cardiovasc Diabetol (2007)

Bottom Line: Rosiglitazone and pioglitazone showed modest but statistically significantly greater inhibitory activity under high versus low glucose conditions (P < 0.05 and P < 0.001, respectively).The activity of rosiglitazone and pioglitazone is enhanced under high glucose conditions.These data provide further in vitro evidence for the potential efficacy of TZDs in preventing multiple cardiovascular diseases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Monash University, Faculty of Medicine, Nursing and Health Sciences, Alfred Hospital, Melbourne, 3004, VIC, Australia. peter.little@baker.edu.au

ABSTRACT

Background: Inhibition of vascular smooth muscle cell (vSMC) proliferation by oral anti-hyperglycemic agents may have a role to play in the amelioration of vascular disease in diabetes. Thiazolidinediones (TZDs) inhibit vSMC proliferation but it has been reported that they anomalously stimulate [3H]-thymidine incorporation. We investigated three TZDs, two biguanides and two sulfonylureas for their ability of inhibit vSMC proliferation. People with diabetes obviously have fluctuating blood glucose levels thus we determined the effect of media glucose concentration on the inhibitory activity of TZDs in a vSMC preparation that grew considerably more rapidly under high glucose conditions. We further explored the mechanisms by which TZDs increase [3H]-thymidine incorporation.

Methods: VSMC proliferation was investigated by [3H]-thymidine incorporation into DNA and cell counting. Activation and inhibition of thymidine kinase utilized short term [3H]-thymidine uptake. Cell cycle events were analyzed by FACS.

Results: VSMC cells grown for 3 days in DMEM with 5% fetal calf serum under low (5 mM glucose) and high (25 mM glucose) increased in number by 2.5 and 4.7 fold, respectively. Rosiglitazone and pioglitazone showed modest but statistically significantly greater inhibitory activity under high versus low glucose conditions (P < 0.05 and P < 0.001, respectively). We confirmed an earlier report that troglitazone (at low concentrations) causes enhanced incorporation of [3H]-thymidine into DNA but did not increase cell numbers. Troglitazone inhibited serum mediated thymidine kinase induction in a concentration dependent manner. FACS analysis showed that troglitazone and rosiglitazone but not pioglitazone placed a slightly higher percentage of cells in the S phase of a growing culture. Of the biguanides, metformin had no effect on proliferation assessed as [3H]-thymidine incorporation or cell numbers whereas phenformin was inhibitory in both assays albeit at high concentrations. The sulfonylureas chlorpropamide and gliclazide had no inhibitory effect on vSMC proliferation assessed by either [3H]-thymidine incorporation or cell numbers.

Conclusion: TZDs but not sulfonylureas nor biguanides (except phenformin at high concentrations) show favorable vascular actions assessed as inhibition of vSMC proliferation. The activity of rosiglitazone and pioglitazone is enhanced under high glucose conditions. These data provide further in vitro evidence for the potential efficacy of TZDs in preventing multiple cardiovascular diseases. However, the plethora of potentially beneficial actions of TZDs in cell and animal models have not been reflected in the results of major clinical trials and a greater understanding of these complex drugs is required to delineate their ultimate clinical utility in preventing macrovascular disease in diabetes.

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Assessment of the cell cycle state of human vSMCs following treatment with clinical TZDs. S phase fraction in cultures treated with TZDs either Troglitazone, Rosiglitazone or Pioglitazone (1 μM each) in the presence of PDGF (50 ng/mL) for 24 h as compared with untreated controls. S phase fraction was analysed by flow cytometry using DNA staining with propidium iodide.
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Figure 4: Assessment of the cell cycle state of human vSMCs following treatment with clinical TZDs. S phase fraction in cultures treated with TZDs either Troglitazone, Rosiglitazone or Pioglitazone (1 μM each) in the presence of PDGF (50 ng/mL) for 24 h as compared with untreated controls. S phase fraction was analysed by flow cytometry using DNA staining with propidium iodide.

Mentions: Troglitazone treatment of vSMC increases [3H]-thymidine incorporation into newly synthesized DNA which implies that more cells are in the S phase of the cell cycle. We used FACS to investigate the effects of the three TZDs on cell cycle progression in vSMCs. The treatment of vSMCs with troglitazone and rosiglitazone resulted in a small increase in cells in the S phase (Fig. 4). In contrast, treatment of cells with pioglitazone reduced the proportion of cells in the S phase of the cell cycle (Fig. 4). The data indicates that the [3H]-thymidine incorporation truly reflects an increased number of cells in the S phase in the presence of rosiglitazone and troglitazone however this does not result in cell cycle progression as no increase in cell numbers is observed [12].


Anti-proliferative activity of oral anti-hyperglycemic agents on human vascular smooth muscle cells: thiazolidinediones (glitazones) have enhanced activity under high glucose conditions.

Little PJ, Osman N, de Dios ST, Cemerlang N, Ballinger M, Nigro J - Cardiovasc Diabetol (2007)

Assessment of the cell cycle state of human vSMCs following treatment with clinical TZDs. S phase fraction in cultures treated with TZDs either Troglitazone, Rosiglitazone or Pioglitazone (1 μM each) in the presence of PDGF (50 ng/mL) for 24 h as compared with untreated controls. S phase fraction was analysed by flow cytometry using DNA staining with propidium iodide.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211460&req=5

Figure 4: Assessment of the cell cycle state of human vSMCs following treatment with clinical TZDs. S phase fraction in cultures treated with TZDs either Troglitazone, Rosiglitazone or Pioglitazone (1 μM each) in the presence of PDGF (50 ng/mL) for 24 h as compared with untreated controls. S phase fraction was analysed by flow cytometry using DNA staining with propidium iodide.
Mentions: Troglitazone treatment of vSMC increases [3H]-thymidine incorporation into newly synthesized DNA which implies that more cells are in the S phase of the cell cycle. We used FACS to investigate the effects of the three TZDs on cell cycle progression in vSMCs. The treatment of vSMCs with troglitazone and rosiglitazone resulted in a small increase in cells in the S phase (Fig. 4). In contrast, treatment of cells with pioglitazone reduced the proportion of cells in the S phase of the cell cycle (Fig. 4). The data indicates that the [3H]-thymidine incorporation truly reflects an increased number of cells in the S phase in the presence of rosiglitazone and troglitazone however this does not result in cell cycle progression as no increase in cell numbers is observed [12].

Bottom Line: Rosiglitazone and pioglitazone showed modest but statistically significantly greater inhibitory activity under high versus low glucose conditions (P < 0.05 and P < 0.001, respectively).The activity of rosiglitazone and pioglitazone is enhanced under high glucose conditions.These data provide further in vitro evidence for the potential efficacy of TZDs in preventing multiple cardiovascular diseases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Monash University, Faculty of Medicine, Nursing and Health Sciences, Alfred Hospital, Melbourne, 3004, VIC, Australia. peter.little@baker.edu.au

ABSTRACT

Background: Inhibition of vascular smooth muscle cell (vSMC) proliferation by oral anti-hyperglycemic agents may have a role to play in the amelioration of vascular disease in diabetes. Thiazolidinediones (TZDs) inhibit vSMC proliferation but it has been reported that they anomalously stimulate [3H]-thymidine incorporation. We investigated three TZDs, two biguanides and two sulfonylureas for their ability of inhibit vSMC proliferation. People with diabetes obviously have fluctuating blood glucose levels thus we determined the effect of media glucose concentration on the inhibitory activity of TZDs in a vSMC preparation that grew considerably more rapidly under high glucose conditions. We further explored the mechanisms by which TZDs increase [3H]-thymidine incorporation.

Methods: VSMC proliferation was investigated by [3H]-thymidine incorporation into DNA and cell counting. Activation and inhibition of thymidine kinase utilized short term [3H]-thymidine uptake. Cell cycle events were analyzed by FACS.

Results: VSMC cells grown for 3 days in DMEM with 5% fetal calf serum under low (5 mM glucose) and high (25 mM glucose) increased in number by 2.5 and 4.7 fold, respectively. Rosiglitazone and pioglitazone showed modest but statistically significantly greater inhibitory activity under high versus low glucose conditions (P < 0.05 and P < 0.001, respectively). We confirmed an earlier report that troglitazone (at low concentrations) causes enhanced incorporation of [3H]-thymidine into DNA but did not increase cell numbers. Troglitazone inhibited serum mediated thymidine kinase induction in a concentration dependent manner. FACS analysis showed that troglitazone and rosiglitazone but not pioglitazone placed a slightly higher percentage of cells in the S phase of a growing culture. Of the biguanides, metformin had no effect on proliferation assessed as [3H]-thymidine incorporation or cell numbers whereas phenformin was inhibitory in both assays albeit at high concentrations. The sulfonylureas chlorpropamide and gliclazide had no inhibitory effect on vSMC proliferation assessed by either [3H]-thymidine incorporation or cell numbers.

Conclusion: TZDs but not sulfonylureas nor biguanides (except phenformin at high concentrations) show favorable vascular actions assessed as inhibition of vSMC proliferation. The activity of rosiglitazone and pioglitazone is enhanced under high glucose conditions. These data provide further in vitro evidence for the potential efficacy of TZDs in preventing multiple cardiovascular diseases. However, the plethora of potentially beneficial actions of TZDs in cell and animal models have not been reflected in the results of major clinical trials and a greater understanding of these complex drugs is required to delineate their ultimate clinical utility in preventing macrovascular disease in diabetes.

Show MeSH
Related in: MedlinePlus