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CDK5 and its activator P35 in normal pituitary and in pituitary adenomas: relationship to VEGF expression.

Xie W, Wang H, He Y, Li D, Gong L, Zhang Y - Int. J. Biol. Sci. (2014)

Bottom Line: The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35).Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis.Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

View Article: PubMed Central - PubMed

Affiliation: Beijing Neurosurgical Institute, Beijing Tiantan Hospital Affiliated to Capital Medical University, Beijing 100050, China.

ABSTRACT
Pituitary tumors are monoclonal adenomas that account for about 10-15% of intracranial tumors. Cyclin-dependent kinase 5 (CDK5) regulates the activities of various proteins and cellular processes in the nervous system, but its potential roles in pituitary adenomas are poorly understood. The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35). Here, we show that functional CDK5, associated with p35, is present in normal human pituitary and in pituitary tumors. Furthermore, p35 mRNA and protein levels were higher in pituitary adenomas than in the normal glands, suggesting that CDK5 activity might be upregulated in pituitary tumors. Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis. Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

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A, Pretreatment with roscovitine significantly decreased VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5B, Effect of Cdk5 siRNA on VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5C, Quantification of the level of VEGF secretion from vehicle or roscovitine-treated GH3 cells. Reduction of VEGF secretion were detected in roscovitine-treated GH3 cells compared with vehicle group; 5D, Quantification of the level of VEGF secretion from control siRNA or CDK5 siRNA-transfected GH3 cells. Reduction of VEGF secretion were detected in CDK5 siRNA-transfected GH3 cells compared with vehicle group. VEGF secretion was quantified as by ELISA as described above. Data represents means ± SEM of three independent experiments. one-way ANOVA was performed to determine the significance (**p < 0.01 and ***p < 0.001).
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Figure 5: A, Pretreatment with roscovitine significantly decreased VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5B, Effect of Cdk5 siRNA on VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5C, Quantification of the level of VEGF secretion from vehicle or roscovitine-treated GH3 cells. Reduction of VEGF secretion were detected in roscovitine-treated GH3 cells compared with vehicle group; 5D, Quantification of the level of VEGF secretion from control siRNA or CDK5 siRNA-transfected GH3 cells. Reduction of VEGF secretion were detected in CDK5 siRNA-transfected GH3 cells compared with vehicle group. VEGF secretion was quantified as by ELISA as described above. Data represents means ± SEM of three independent experiments. one-way ANOVA was performed to determine the significance (**p < 0.01 and ***p < 0.001).

Mentions: To explore the possible link between CDK5-p35 and VEGF in pituitary adenomas, we incubated rat pituitary GH3 cells with either DMSO or different concentrations of roscovitine (a CDK5 inhibitor). As shown in Fig. 5A, VEGF expression was significantly reduced after treatment with roscovitine, suggesting that CDK5 regulates VEGF expression. The involvement of Cdk5 is further supported by studies using short interfering RNA (siRNA) targeting the Cdk5 mRNA in GH3 cells. We found a significant decrease of VEGF in cells transfected with Cdk5 siRNA, compared with cells transfected with control siRNA (Fig. 5B).


CDK5 and its activator P35 in normal pituitary and in pituitary adenomas: relationship to VEGF expression.

Xie W, Wang H, He Y, Li D, Gong L, Zhang Y - Int. J. Biol. Sci. (2014)

A, Pretreatment with roscovitine significantly decreased VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5B, Effect of Cdk5 siRNA on VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5C, Quantification of the level of VEGF secretion from vehicle or roscovitine-treated GH3 cells. Reduction of VEGF secretion were detected in roscovitine-treated GH3 cells compared with vehicle group; 5D, Quantification of the level of VEGF secretion from control siRNA or CDK5 siRNA-transfected GH3 cells. Reduction of VEGF secretion were detected in CDK5 siRNA-transfected GH3 cells compared with vehicle group. VEGF secretion was quantified as by ELISA as described above. Data represents means ± SEM of three independent experiments. one-way ANOVA was performed to determine the significance (**p < 0.01 and ***p < 0.001).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927131&req=5

Figure 5: A, Pretreatment with roscovitine significantly decreased VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5B, Effect of Cdk5 siRNA on VEGF expression in GH3 cells. Blots were reprobed with anti- GAPDH antibody to en sure equal loading; 5C, Quantification of the level of VEGF secretion from vehicle or roscovitine-treated GH3 cells. Reduction of VEGF secretion were detected in roscovitine-treated GH3 cells compared with vehicle group; 5D, Quantification of the level of VEGF secretion from control siRNA or CDK5 siRNA-transfected GH3 cells. Reduction of VEGF secretion were detected in CDK5 siRNA-transfected GH3 cells compared with vehicle group. VEGF secretion was quantified as by ELISA as described above. Data represents means ± SEM of three independent experiments. one-way ANOVA was performed to determine the significance (**p < 0.01 and ***p < 0.001).
Mentions: To explore the possible link between CDK5-p35 and VEGF in pituitary adenomas, we incubated rat pituitary GH3 cells with either DMSO or different concentrations of roscovitine (a CDK5 inhibitor). As shown in Fig. 5A, VEGF expression was significantly reduced after treatment with roscovitine, suggesting that CDK5 regulates VEGF expression. The involvement of Cdk5 is further supported by studies using short interfering RNA (siRNA) targeting the Cdk5 mRNA in GH3 cells. We found a significant decrease of VEGF in cells transfected with Cdk5 siRNA, compared with cells transfected with control siRNA (Fig. 5B).

Bottom Line: The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35).Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis.Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

View Article: PubMed Central - PubMed

Affiliation: Beijing Neurosurgical Institute, Beijing Tiantan Hospital Affiliated to Capital Medical University, Beijing 100050, China.

ABSTRACT
Pituitary tumors are monoclonal adenomas that account for about 10-15% of intracranial tumors. Cyclin-dependent kinase 5 (CDK5) regulates the activities of various proteins and cellular processes in the nervous system, but its potential roles in pituitary adenomas are poorly understood. The kinase activity of CDK5 requires association with an activating protein, p35 (also known as CDK5 activator 1, p35). Here, we show that functional CDK5, associated with p35, is present in normal human pituitary and in pituitary tumors. Furthermore, p35 mRNA and protein levels were higher in pituitary adenomas than in the normal glands, suggesting that CDK5 activity might be upregulated in pituitary tumors. Inhibition of CDK5 activity in rat pituitary cells, reduced the expression of vascular endothelial growth factor (VEGF), a protein that regulates vasculogenesis and angiogenesis. Our results suggest that increased CDK5-mediated VEGF expression might play a crucial role in the development of pituitary adenomas, and that roscovitine and other CDK5 inhibitors could be useful as anticancer agents.

Show MeSH
Related in: MedlinePlus