Journal Article

Regulation of Cdk7 activity through a phosphatidylinositol (3)-kinase/PKC-ι-mediated signaling cascade in glioblastoma

Shraddha R. Desai, Prajit P. Pillai, Rekha S. Patel, Andrea N. McCray, Hla Y. Win-Piazza and Mildred E. Acevedo-Duncan

in Carcinogenesis

Volume 33, issue 1, pages 10-19
Published in print January 2012 | ISSN: 0143-3334
Published online October 2011 | e-ISSN: 1460-2180 | DOI:
Regulation of Cdk7 activity through a phosphatidylinositol (3)-kinase/PKC-ι-mediated signaling cascade in glioblastoma

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The objective of this research was to study the potential function of protein kinase C (PKC)-ι in cell cycle progression and proliferation in glioblastoma. PKC-ι is highly overexpressed in human glioma and benign and malignant meningioma; however, little is understood about its role in regulating cell proliferation of glioblastoma. Several upstream molecular aberrations and/or loss of PTEN have been implicated to constitutively activate the phosphatidylinositol (PI) (3)-kinase pathway. PKC-ι is a targeted mediator in the PI (3)-kinase signal transduction repertoire. Results showed that PKC-ι was highly activated and overexpressed in glioma cells. PKC-ι directly associated and phosphorylated Cdk7 at T170 in a cell cycle-dependent manner, phosphorylating its downstream target, cdk2 at T160. Cdk2 has a major role in inducing G1–S phase progression of cells. Purified PKC-ι phosphorylated both endogenous and exogenous Cdk7. PKC-ι downregulation reduced Cdk7 and cdk2 phosphorylation following PI (3)-kinase inhibition, phosphotidylinositol-dependent kinase 1 knockdown as well as PKC-ι silencing (by siRNA treatment). It also diminished cdk2 activity. PKC-ι knockdown inhibited overall proliferation rates and induced apoptosis in glioma cells. These findings suggest that glioma cells may be proliferating through a novel PI (3)-kinase-/PKC-ι/Cdk7/cdk2-mediated pathway.

Journal Article.  6538 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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