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Cathepsin B and uPAR regulate self-renewal of glioma-initiating cells through GLI-regulated Sox2 and Bmi1 expression.

ABSTRACT: Cancer-initiating cells comprise a heterogeneous population of undifferentiated cells with the capacity for self-renewal and high proliferative potential. We investigated the role of uPAR and cathepsin B in the maintenance of stem cell nature in glioma-initiating cells (GICs). Simultaneous knockdown of uPAR and cathepsin B significantly reduced the expression of CD133, Nestin, Sox2 and Bmi1 at the protein level and GLI1 and GLI2 at the messenger RNA level. Also, knockdown of uPAR and cathepsin B resulted in a reduction in the number of GICs as well as sphere size. These changes are mediated by Sox2 and Bmi1, downstream of hedgehog signaling. Addition of cyclopamine reduced the expression of Sox2 and Bmi1 along with GLI1 and GLI2 expression, induced differentiation and reduced subsphere formation of GICs thereby indicating that hedgehog signaling acts upstream of Sox2 and Bmi1. Further confirmation was obtained from increased luciferase expression under the control of a GLI-bound Sox2 and Bmi1 luciferase promoter. Simultaneous knockdown of uPAR and cathepsin B also reduced the expression of Nestin Sox2 and Bmi1 in vivo. Thus, our study highlights the importance of uPAR and cathepsin B in the regulation of malignant stem cell self-renewal through hedgehog components, Bmi1 and Sox2.

SUBMITTER: Gopinath S

PROVIDER: S-EPMC3581601 | biostudies-literature | 2013 Mar

REPOSITORIES: biostudies-literature

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Cathepsin B and uPAR regulate self-renewal of glioma-initiating cells through GLI-regulated Sox2 and Bmi1 expression.

Gopinath Sreelatha S Malla Ramarao R Alapati Kiranmai K Gorantla Bharathi B Gujrati Meena M Dinh Dzung H DH Rao Jasti S JS

Carcinogenesis 20121207 3

Cancer-initiating cells comprise a heterogeneous population of undifferentiated cells with the capacity for self-renewal and high proliferative potential. We investigated the role of uPAR and cathepsin B in the maintenance of stem cell nature in glioma-initiating cells (GICs). Simultaneous knockdown of uPAR and cathepsin B significantly reduced the expression of CD133, Nestin, Sox2 and Bmi1 at the protein level and GLI1 and GLI2 at the messenger RNA level. Also, knockdown of uPAR and cathepsin B ...[more]

PMID: 23222817

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Project description:BackgroundMeningiomas are the most commonly occurring intracranial tumors and account for approximately 15-20% of central nervous system tumors. Surgery and radiation therapy is a common treatment for brain tumors, however, patients whose tumors recur after such treatments have limited therapeutic options. Earlier studies have reported important roles of uPA, uPAR and cathepsin B in tumor progression.Methodology/principal findingsIn the present study, we examined the therapeutic significance of RNAi-mediated simultaneous down regulation of these proteolytic networks using two bicistronic siRNA constructs, pUC (uPAR/cathepsin B) and pU2 (uPA/uPAR) either alone or in combination with radiation in two different meningioma cell lines. Transfection of meningioma cells with pUC and pU2 significantly reduced angiogenesis as compared to control treatment both in vitro and in vivo nude mice model. This effect is mediated by inhibiting angiogenic molecules (Ang-1, Ang-2 and VEGF). Expression of focal adhesion kinase (FAK) is elevated in malignant meningioma, yet the role of intrinsic FAK activity in promoting tumor progression remains undefined. We found that pUC treatment reduced FAK phosphorylation at Y925 more efficiently compared to pU2 treatment. In immunoprecipitation assay, we found pronounced reduction of FAK (Y925) interaction with Grb2 in meningioma cells transfected with pUC with and without irradiation. Transient over-expression of uPAR and cathepsin B by full length uPAR/cathepsin B (FLpU/C) in pUC transfected meningioma cells promoted vascular phenotype, rescued expression of Ang-1, Ang-2, VEGF, FAK (Y925) and Grb2 both in vitro and in vivo mice model.Conclusion/significanceThese studies provide the first direct proof that bicistronic siRNA construct for uPAR and cathepsin B (pUC) reduces Y925-FAK activity and this inhibition is rescued by overexpression of both uPAR and cathepsin B which clearly demonstrates that pUC could thus be a potential therapeutic approach as an anti-angiogenic agent in meningioma.

Dataset Information

Cathepsin B and uPAR regulate self-renewal of glioma-initiating cells through GLI-regulated Sox2 and Bmi1 expression.

Publications

Cathepsin B and uPAR regulate self-renewal of glioma-initiating cells through GLI-regulated Sox2 and Bmi1 expression.

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