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  • 1
    In: Experimental and Molecular Pathology, Elsevier BV, Vol. 128 ( 2022-10), p. 104813-
    Type of Medium: Online Resource
    ISSN: 0014-4800
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2022
    detail.hit.zdb_id: 1466769-1
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  • 2
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2023-08-01)
    Abstract: GBM (Glioblastoma) is the most lethal CNS (Central nervous system) tumor in adults, which inevitably develops resistance to standard treatments leading to recurrence and mortality. TRIB1 is a serine/threonine pseudokinase which functions as a scaffold platform that initiates degradation of its substrates like C/EBPα through the ubiquitin proteasome system and also activates MEK and Akt signaling. We found that increased TRIB1 gene expression associated with worse overall survival of GBM patients across multiple cohorts. Importantly, overexpression of TRIB1 decreased RT/TMZ (radiation therapy/temozolomide)-induced apoptosis in patient derived GBM cell lines in vitro. TRIB1 directly bound to MEK and Akt and increased ERK and Akt phosphorylation/activation. We also found that TRIB1 protein expression was maximal during G2/M transition of cell cycle in GBM cells. Furthermore, TRIB1 bound directly to HDAC1 and p53. Importantly, mice bearing TRIB1 overexpressing tumors had worse overall survival. Collectively, these data suggest that TRIB1 induces resistance of GBM cells to RT/TMZ treatments by activating the cell proliferation and survival pathways thus providing an opportunity for developing new targeted therapeutics.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2615211-3
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  • 3
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 21, No. Supplement_6 ( 2019-11-11), p. vi209-vi210
    Abstract: Glioblastoma is the most aggressive brain tumor with poor prognosis despite the best available treatment. MicroRNAs (miRNAs) are emerging as promising, novel prognostic biomarkers and therapeutic targets in glioblastoma. In a previous study, we demonstrated that miR-4516 predicts poor prognosis and functions as an oncogene in glioblastoma. Aim of the current study is to examine the role miR-4516 in radiation resistance and identify downstream targets contributing to this phenotype METHODS Radiosensitization was evaluated by cell viability and clonogenic assays. Cell apoptosis was evaluated using flow cytometry and immunoblotting. Potential targets of miR-4516 were identified using bioinformatic analysis (Targetscan and miRDB) and confirmed by luciferase reporter assays. Results were validated using immunoblotting. miR-4516 expression in glioblastoma cell lines after radiation treatment was quantified by qRT-PCR. RESULTS Expression of miR-4516 was increased up to 15 fold following radiation treatment, peaking at around 15min-60 min in primary and established glioblastoma cell lines including GBM 08-387, GBM 30 and U87-MG. Furthermore, inhibition of miR-4516 sensitized GBM 08-387, GBM30 and U87-MG cells to radiation in comparison to control groups as determined by cell viability and clonogenic assays. Further, miR-4516 inhibition induced apoptosis in these cell lines following radiation treatment. While conducting mechanistic studies, we found that the tumor-promoting function of miR-4516 was, in part, mediated by inhibition of p21 and PTPN14, two direct targets of miR-4516 CONCLUSION Our data suggest that radiation induces the expression of miR-4516 in glioblastoma cell lines. This miRNA plays a critical role in radio-resistance and promotes aggressive phenotypes in glioblastoma and therefore, functional analyses of its target pathways may uncover novel therapeutically vulnerable target(s) in glioblastoma. FUNDING: R01CA108633, R01CA169368, RC2CA148190, U10CA180850-01(NCI), Brain Tumor Funders Collaborative Grant, and OSU-CCC (all to AC). The Ton and Patricia Bohnenn Fund for Neuro_Oncology Research (to PR).
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 2094060-9
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  • 4
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 21, No. Supplement_6 ( 2019-11-11), p. vi50-vi50
    Abstract: Glioblastomas (GBMs) are the most aggressive primary brain tumors, with an average survival time of less than 15 months. miRNAs are emerging as promising and novel biomarkers in GBM. The aims of this study are: 1) to investigate novel miRNAs biomarkers that affect tumorigenesis and therapeutic sensitivity, and 2) to study the underlying molecular mechanisms in GBM. METHODS Nanostring v3 was performed followed by univariable (UVA) and multivariable (MVA) analyses. Functional studies were conducted to define the role of miR-146a in GBM tumorigenesis and therapeutic response and the molecular mechanisms were investigated. RESULTS UVA analyses demonstrated that miR-146a is one of the top miRNAs that correlated with better prognosis in GBM patients (p=9.21E-05), which was independent of MGMT promoter methylation by MVA analyses (p 〈 0.001). miR-146a expression was significantly downregulated in recurrent GBM tumors compared with the paired primary GBM tumors (p=0.003). Overexpression of miR-146a significantly inhibited tumor cell growth and sensitized patient-derived primary GBM cells to temozolomide (TMZ) treatment in vitro, and showed statistically significant smaller tumor size (p 〈 0.01) and prolonged survival (p=0.001) in vivo. In addition, miR-146a is downregulated in glioma cancer stem cells, and overexpression of miR-146a significantly affected glioma cancer stem cell self-renewal. We also found that overexpression of miR-146a significantly inhibited the NF-κB, AKT, and ERK pathways. CONCLUSION Our data suggest, for the first time, that miR-146a predicts favorable prognosis for GBM patients and sensitizes primary GBM cells to TMZ treatment in vitro and in vivo through regulating glioma stem cells. Importantly, miR-146a may prove to be a master switch shutting off AKT, NF-κB, as well as other pathways and may overcome redundancies among these pathways leading to resistance. FUNDING: Bohnenn Fund (to PR), R01CA108633, R01CA169368, U10CA180850-01(NCI), Brain Tumor Funders Collaborative Grant, and The Ohio State University CCC (all to AC).
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 2094060-9
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  • 5
    In: Neuro-Oncology, Oxford University Press (OUP), Vol. 23, No. Supplement_6 ( 2021-11-12), p. vi39-vi39
    Abstract: Glioblastoma (GBM) is the most aggressive CNS tumor with an average survival of about 15 months after diagnosis. The current gold standard therapy comprises radiation therapy (RT) and concurrent and adjuvant temozolamide (TMZ). Due to poor prognosis, novel therapeutic targets need to be identified for drug development. To this end, we identified TRIB1 through correlative studies using patient derived methylation data from an institutional cohort as a novel therapeutic target. TRIB1 is a Ser/Thr pseudokinase that functions as a scaffold for the degradation of its substrates and activates Akt and MEK oncogenic pathways. In this study, we show that TRIB1 promoted GBM progression by upregulating survival pathways and reducing RT/TMZ-induced cell death. MATERIALS AND METHODS In vitro functional validation was performed by overexpression and knockdown approaches. GBM patient derived (PDX) cell lines overexpressing the TRIB1 transgene were used to create an orthotopic tumor model for in vivo studies. Mice were monitored for changes in tumor volume and overall survival. Stable cell lines were generated by puromycin selection. Western blotting was utilized to detect protein levels. RESULTS Mice inoculated with PDX cells overexpressing TRIB1 transgene had increased tumor volume and worse overall survival compared to the empty vector control. We also observed that TRIB1 overexpression caused decreased apoptosis of PDX cell lines after RT/TMZ treatment. Additionally, an increase in the phosphorylation of ERK and Akt was also noted after TRIB1 overexpression. Consistent with these observations, TRIB1 knockdown sensitized the cells towards radiation and caused decreased Akt phosphorylation/activation as well. CONCLUSION TRIB1 overexpression decreases overall survival of xenograft bearing mice and promotes GBM cell survival by upregulating survival signaling pathways. This compromises the effects of RT/TMZ therapy, which is reversed after TRIB1 knockdown. Targeting of TRIB1 may reduce oncogenic signaling in GBM cells and therefore would sensitize them towards RT/TMZ therapy.
    Type of Medium: Online Resource
    ISSN: 1522-8517 , 1523-5866
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 2094060-9
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  • 6
    In: Molecular Cancer Research, American Association for Cancer Research (AACR), Vol. 19, No. 1 ( 2021-01-01), p. 48-60
    Abstract: Rapid tumor growth, widespread brain-invasion, and therapeutic resistance critically contribute to glioblastoma (GBM) recurrence and dismal patient outcomes. Although GBM stem cells (GSC) are shown to play key roles in these processes, the molecular pathways governing the GSC phenotype (GBM-stemness) remain poorly defined. Here, we show that epigenetic silencing of miR-146a significantly correlated with worse patient outcome and importantly, miR-146a level was significantly lower in recurrent tumors compared with primary ones. Further, miR-146a overexpression significantly inhibited the proliferation and invasion of GBM patient-derived primary cells and increased their response to temozolomide (TMZ), both in vitro and in vivo. Mechanistically, miR-146a directly silenced POU3F2 and SMARCA5, two transcription factors that mutually regulated each other, significantly compromising GBM-stemness and increasing TMZ response. Collectively, our data show that miR-146a–POU3F2/SMARCA5 pathway plays a critical role in suppressing GBM-stemness and increasing TMZ-response, suggesting that POU3F2 and SMARCA5 may serve as novel therapeutic targets in GBM. Implications: miR-146a predicts favorable prognosis and the miR-146a–POU3F2/SMARCA5 pathway is important for the suppression of stemness in GBM.
    Type of Medium: Online Resource
    ISSN: 1541-7786 , 1557-3125
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2021
    detail.hit.zdb_id: 2097884-4
    SSG: 12
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