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UPAR and cathepsin B inhibition enhanced radiation-induced apoptosis in gliomainitiating cells.

ABSTRACT: Glioblastomas present as diffuse tumors with invasion into normal brain tissue and frequently recur or progress after radiation as focal masses because of glioma-initiating cells. The role of the urokinase-type plasminogen activator receptor (uPAR) and cathepsin B in stem-like phenotype has been extensively studied in several solid tumors. In the present study, we demonstrated that selection of glioma-initiating cells using CD133 expression leads to a specific enrichment of CD133(+) cells in both U87 and 4910 cells. In addition, CD133(+) cells exhibited a considerable amount of other stem cell markers, such as Nestin and Sox-2. Radiation treatment significantly enhanced uPAR and cathepsin B levels in glioma-initiating cells. To downregulate radiation-induced uPAR and cathepsin B expression, we used a bicistronic shRNA construct that simultaneously targets both uPAR and cathepsin B (pCU). Downregulation of uPAR and cathepsin B using pCU decreased radiation-enhanced uPAR and cathepsin B levels and caused DNA damage-induced apoptosis in glioma cell lines and glioma-initiating cells. The most striking finding of this study is that knockdown of uPAR and cathepsin B inhibited ongoing transcription by suppressing BrUTP incorporation at γH2AX foci. In addition, uPAR and cathepsin B gene silencing inversely regulated survivin and H2AX expression in both glioma cells and glioma-initiating cells. Pretreatment with pCU reduced radiation-enhanced expression of uPAR, cathepsin B, and survivin and enhanced DNA damage in pre-established glioma in nude mice. Taken together, our in vitro and in vivo findings suggest that uPAR and cathepsin B inhibition might serve as an adjunct to radiation therapy to target glioma-initiating cells and, therefore, for the treatment of glioma.

SUBMITTER: Malla RR

PROVIDER: S-EPMC3367854 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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uPAR and cathepsin B inhibition enhanced radiation-induced apoptosis in gliomainitiating cells.

Malla Rama Rao RR Gopinath Sreelatha S Alapati Kiranmai K Gorantla Bharathi B Gondi Christopher S CS Rao Jasti S JS

Neuro-oncology 20120509 6

Glioblastomas present as diffuse tumors with invasion into normal brain tissue and frequently recur or progress after radiation as focal masses because of glioma-initiating cells. The role of the urokinase-type plasminogen activator receptor (uPAR) and cathepsin B in stem-like phenotype has been extensively studied in several solid tumors. In the present study, we demonstrated that selection of glioma-initiating cells using CD133 expression leads to a specific enrichment of CD133(+) cells in bot ...[more]

PMID: 22573309

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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.

Project description:PurposeStrategies to increase radiosensitivity are urgently needed. Combining radiosensitizing reagents with radiotherapy could improve the outcome of cancer treatment. Some preclinical studies showed that sepantronium bromide (YM155) could sensitize cancer cells to radiation by inhibiting the survivin protein. In this study, we try to investigate the function of YM155 on radiosensitivity of esophageal squamous cell carcinoma (ESCC) cells.Materials and methodsESCC cell lines were treated with radiation and YM155, and the radiation efficacy was evaluated by cell counting kit-8 assay and clonogenic survival assay. Cell senescence was measured by senescence-associated β-galactosidase staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, fluorescein isothiocyanate-labeled Annexin V/propidium iodide assay, and poly ADP-ribose polymerase cleavage were used to detect apoptosis. KYSE150 xenografts model was used to test the efficacy of radiation combined with YM155.ResultsYM155 could inhibit the upregulation of survivin induced by radiation in all ESCC cell lines, but the efficacy of radiosensitization varied in different cell lines. Radiation-induced senescence in KYSE150 and KYSE410 cells, and the combination with YM155 inhibited senescence and promoted apoptosis of ESCC cells, thereby enhancing radiosensitivity. Combination with YM155 and radiation delayed the growth of KYSE150 xenografts in nude mice by switching radiation-induced senescence to apoptosis. When p21 was inhibited in KYSE150 cells, radiation did not induce senescence, and the radiosensitization of YM155 was also attenuated. In KYSE510 and KYSE180 cells, radiation did not induce senescence, and YM155 could not enhance the radiosensitivity.ConclusionOur results suggest a new mechanism that YM155 might sensitize ESCC cells to radiation by switching radiation-induced senescence to apoptosis. The major determinant of radiosensitization by YM155 might be the induction of senescence by radiation.

Project description:ObjectiveWhereas prostate cancer (PrCa) may be unresponsive or moderately responsive to radiation therapy (RT)- most common modality for treatment of PrCa- patients must receive a high dose of RT In order to achieve appropriate tumour control. However, this increase in radiation dose may lead to severe adverse effects in normal tissues. Sensitization of PrCa to radiation provides an alternate approach to improve the therapeutic efficacy of RT. This study aims to assess the radiosensitisation effect of apigenin (Api) on a prostate cancer cell line (LNCaP).Materials and methodsIn this experimental study, LNCaP cells were treated with 0-80 μM Api to investigate its effect on LNCaP cell viability and determine its half-maximal inhibitory concentration (IC50). Next, the cells were divided into four groups: i. Control, ii. Cells treated with the IC50 concentration of Api, iii. Cells treated with 2 Gy ionizing radiation (IR), and cells co-treated with Api and IR. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, real-time polymerase chain reaction (PCR), and an Annexin V-FITC/PI assay were performed to assess cell survival, Bax and Bcl-2 expressions, and presence of apoptosis and necrosis.ResultsApi inhibited cell survival in a dose-dependent, but not time-dependent manner. Cells treated with Api had increased amounts of early apoptosis, late apoptosis, and secondary necrosis compared to the control group. This group also had decreased Bcl-2 gene expression and up-regulated Bax gene expression. Co-treatment with Api and IR significantly inhibited cell survival, and increased early apoptosis, late apoptosis and secondary necrosis compared to the other groups. There was a significant decrease in Bcl-2 gene expression along with up-regulation of Bax gene expression, and Bax/Bcl-2 ratio changes that favoured apoptosis.ConclusionApi inhibited PrCa cell survival and induced apoptosis as a single agent. In addition, Api significantly sensitized the LNCaP cells to IR and enhanced radiation-induced apoptosis.

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UPAR and cathepsin B inhibition enhanced radiation-induced apoptosis in gliomainitiating cells.

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uPAR and cathepsin B inhibition enhanced radiation-induced apoptosis in gliomainitiating cells.

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