Enhanced radiosensitivity and radiation-induced apoptosis in glioma CD133-positive cells by knockdown of SirT1 expression (original) (raw)
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miRNA regulation of Sirtuin-1 expression in human astrocytoma
Oncology Letters, 2016
Sirtuins are a family of 7 histone deacetylases largely involved in the regulation of cell proliferation, survival and death. The role of sirtuins in tumorigenesis and cancer progression has been previously studied in certain cancer types. Few studies have investigated sirtuin expression in gliomas, with controversial results. The aim of the present study was to investigate the expression of sirtuin-1 (Sirt-1) in diffuse astrocytoma [low grade astrocytoma (LGA)], anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM) and in primary glioma cell lines: PLGAC (primary LGA cells); PAAC (primary AA cells); and PGBMC (primary GBM cells). Tumor samples were obtained from patients who underwent craniotomy for microsurgical tumor resection at the Neurosurgery Unit of the University of Messina between 2011 and 2014. Sirt-1 expression was qualitatively analyzed in 30 human glial tumor samples and 5 non-neoplastic brain tissue (NBT) specimens using immunohistochemistry and western blotting techniques. Sirt-1 expression was quantitatively analyzed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In addition, Sirt-1 expression in primary cell lines was investigated by immunoblotting and RT-qPCR. Sirt-1 expression was downregulated in gliomas compared to NBTs. Sirt-1 levels also varied among different tumor grades, with more evident downregulation in high-grade (P<0.001) than low-grade tumors (P<0.01). These data were confirmed in cell lines, with the exception of upregulation of protein level in the highest malignancy grade cell lines. The present results suggest a role for miRNA-34a, miRNA-132 and miRNA-217 in the epigenetic control of Sirt-1 during gliomagenesis and progression, and demonstrate the different implications of Sirt-1 in human tissues and cell lines. Furthermore, the present results reveal that Sirt-1 may be an intrinsic regulator of tumor progression and the regulation of Sirt-1 involves complex molecular pathways. However, the biological functions of Sirt-1 in gliomagenesis require additional investigation.
Exploring the Multi-Faceted Role of Sirtuins in Glioblastoma Pathogenesis and Targeting Options
International Journal of Molecular Sciences
Recent advances in glioblastoma (GB) research have shed light on the molecular characteristics, the defected intracellular signaling pathways, and the genetic and epigenetic alterations involved in their pathogenesis. Despite constant efforts, GB remains an aggressive malignant tumor with limited therapeutic approaches, poor prognosis, and a low survival rate. Emerging evidence points towards the crucial impact of epigenetic post-translational modifications in cancer development with emphasis on the regulatory role of histone deacetylation in several key cellular processes, including metabolic pathways, regulation of stress response, senescence, proliferation, DNA repair, and apoptosis. The silent information regulator proteins (Sirtuins) are deacetylases of histone and non-histone proteins that have been recently implicated in the initiation as well as in the progression of GB. Herein, we provide a critical overview of the emerging functional role and mechanism of action of the sev...
Neuro-oncology, 2015
Cancer stemness, observed in several types of glioma stem cells (GSCs), has been demonstrated to be an important barrier for efficient cancer therapy. We have previously reported that cancerous neural stem cells (F3.Ras.CNSCs), derived from immortalized human neural stem cells by a single oncogenic stimulation, form glial tumors in vivo. We searched for a commonly expressed stress modulator in both F3.Ras.CNSCs and GSCs and identified silent mating type information regulation 2, homolog (SIRT1) as a key factor in maintaining cancer stemness. We demonstrate that the expression of SIRT1, expressed in "cancer cells with neural stemness," is critical not only for the maintenance of stem cells, but also for oncogenic transformation. Interestingly, SIRT1 is essential for the survival and tumorigenicity of F3.Ras.CNSCs and GSCs but not for the U87 glioma cell line. These results indicate that expression of SIRT1 in cancer cells with neural stemness plays an important role in supp...
Journal of Radiation Research, 2012
Intratumoral hypoxia is an important contributory factor to tumor cell resistance to radiotherapy. SirT1, a nicotinamide adenine dinucleotide (NAD +)-dependent histone/protein deacetylase, has been linked to the decrease of radiation-induced DNA damage and seems to be critical for cancer therapy. The purpose of this study was to investigate the role of SirT1 in hypoxia-induced radiation response on hepatoma cells. It was found that the administration with resveratrol, a putative SirT1 activator, enhanced the resistance of HepG2 cells against radiation-induced DNA damage of MN formation under hypoxia condition; while nicotinamide, a well-known SirT1 inhibitor, sensitized this radiation damage. Nevertheless, pretreatment of cells with 10058-F4, a specific inhibitor of c-Myc, almost eliminated the nicotinamide-induced radiosensitive effect. Further studies revealed that resveratrol inhibited c-Myc protein accumulation via up-regulation of SirT1 expression and deacetylase activity, and this loss of c-Myc protein was abolished by inhibiting its degradation in the presence of MG132, a potent inhibitor of proteasome. In contrast, nicotinamide attenuated c-Myc protein degradation induced by radiation under hypoxia through inhibition of SirT1 deacetylase activity. Our findings suggest that SirT1 could serve as a novel potent target of radiation-induced DNA damage and thus as a potential strategy to advance the efficiency of radiation therapy in hepatoma entities.
BMC Cancer, 2019
Background: Glioblastoma (GBM) is an extremely deadly form of brain cancer with limited treatment options and thus novel therapeutic modalities are necessary. Histone deacetylase inhibitors (HDACi) have demonstrated clinical and preclinical activities against GBM. (Silent mating type information regulation 2 homolog, Sirt1) abbreviated as Sirtuin 1, has been implicated in GBM. We explored the activity of the Sirt1 activator SRT2183 in glioma cell lines in terms of biological response. Methods: The effects of SRT2183 on glioma cell growth and neurosphere survival were evaluated in vitro using the CCK-8, clonogenic and neurosphere assays, respectively. Glioma cell cycle arrest and apoptosis were determined by flow cytometry. SRT2183-induced autophagy was investigated by detection of GFP-microtubule-associated protein 1 light chain 3 (GFP-LC3) puncta, conversion of the nonlipidated form of LC3 (LC3-I) to the phosphatidylethanolamineconjugated form (LC3-II). Acetylation of STAT3 and NF-κB in SRT2183-treated glioma cells was examined using immunoprecipitation. The expression levels of anti-apoptotic proteins were assayed by immunoblotting. Results: SRT2183 suppressed glioma cell growth and destroyed neurospheres in vitro. Furthermore, SRT2183 induced glioma cell cycle arrest and apoptosis, accompanying by upregulation of the pro-apoptotic Bim and downregulation of Bcl-2 and Bcl-xL. Notably, ER stress was triggered in glioma cells upon exposure to SRT2183 while the pre-exposure to 4-PBA, an ER stress inhibitor, significantly antagonized SRT2183-mediated growth inhibition in glioma cells. In addition, SRT2183 induced autophagy in glioma cells and pharmacological modulation of autophagy appeared not to affect SRT2183inhibited cell growth. Of interest, the acetylation and phosphorylation of p65 NF-κB and STAT3 in glioma cells were differentially affected by SRT2183. Conclusions: Our data suggest the ER stress pathway is involved in SRT2183-mediated growth inhibition in glioma. Further investigation in vivo is needed to consolidate the data.
Inhibition of Sirtuin 6 Induces Neuroblastoma Differentiation
Anticancer research, 2018
Sirtuins (SIRTs) play crucial roles in various signaling pathways that modulate differentiation and proliferation. We sought to elucidate the role of SIRTs in differentiation and proliferation of human neuroblastoma (NB). NB cells were treated with nicotinamide (NAM), a non-specific SIRT inhibitor, SIRT-targeted short hairpin RNAs, and retinoic acid to assess cell growth and differentiation. SIRTs are involved in proliferation and differentiation using NAM in BE(2)-C cells. Specifically, SIRT6 knockdown in BE(2)-C cells reduced cell proliferation, induced neurite extension, corresponding with induction of p21expression and Gcell-cycle arrest. These effects were rescued by forced re-overexpression of SIRT6. SIRT6 expression was reduced in differentiated human NB sections, and RA-induced differentiation in BE(2)-C cells. SIRTs have important oncogenic properties in NB beyond its established functions in aging and genome stability. SIRT6 may represent a novel target for developing futu...
CDK1-mediated SIRT3 Activation Enhances Mitochondrial Function and Tumor Radioresistance
Molecular cancer therapeutics, 2015
The tumor adaptive resistance to therapeutic radiation remains to be a barrier for further improvement of local cancer control. SIRT3, a member of the sirtuin family of NAD+-dependent protein deacetylases in mitochondria, promotes metabolic homeostasis through regulation of mitochondrial protein deacetylation and plays a key role in prevention of cell aging. Here, we demonstrate that SIRT3 expression is induced in an array of radiation-treated human tumor cells and their corresponding xenograft tumors including colon cancer HCT-116, glioblastoma U87 and breast cancer MDA-MB231 cells. The SIRT3 transcriptional activation is due to SIRT3 promoter activation controlled by the stress transcription factor NF-κB. Post-transcriptionally, the SIRT3 enzymatic activity is further enhanced via Thr150/Ser159 phosphorylation by Cyclin B1/CDK1, which is also induced by radiation and relocated to mitochondria together with SIRT3. Cells expressing the Thr150Ala/Ser159Ala mutant SIRT3 show a reducti...
Radiosensitization of Primary Human Glioblastoma Stem-like Cells with Low-Dose AKT Inhibition
Molecular Cancer Therapeutics, 2015
Glioblastoma (GBM) is the most frequent and lethal brain cancer. The lack of early detection methods, the presence of rapidly growing tumor cells, and the high levels of recurrence due to chemo- and radioresistance make this cancer an extremely difficult disease to treat. Emerging studies have focused on inhibiting AKT activation; here, we demonstrate that in primary GBM tumor samples, full-dose inhibition of AKT activity leads to differential responses among samples in the context of cell death and self-renewal, reinforcing the notion that GBM is a heterogeneous disease. In contrast, low-dose AKT inhibition when combined with fractionation of radiation doses leads to a significant apoptosis-mediated cell death of primary patient–derived GBM cells. Therefore, low-dose–targeted therapies might be better for radiosensitization of primary GBM cells and further allow for reducing the clinical toxicities often associated with targeting the AKT/PI3K/mTOR pathway. This work emphasizes the ...
Inhibition of SIRT1 Transcription in Resveratrol-differentiated Medulloblastoma Cells
Backgrounds: Medulloblastoma (MB) is the commonest brain malignancy in childhood with poor prognosis, because of its rapid aggressive growth and frequent occurrence. The current chemotherapeutic regimens for medulloblastoma patients involve a combination of lomustine, cisplatin, carboplatin, vincristine or cyclophosphamide, which have distinct short- and long-term side-effects. It is therefore in urgent need to explore safer and more effective adjuvant approach(s). Resveratrol, a polyphenol rich in numerous plants, has multiple biological activities including anticancer effects. Our previous data confirmed that resveratrol inhibited proliferation and induced differentiation and apoptosis of medulloblastoma cells. SIRT1 is a deacetylase of class III HDACs and the supposed molecular effecter of resveratrol. SIRT1 involves in aging prevention and cancer formation in a cell-context specific manner. Nevertheless, the datum concerning the role(s) of SIRT1 in formation and prognosis of medulloblastoma is still missing. Objective: The present study aimed to address the expression patterna of SIRT1 in medulloblastoma tissues and non-cancerous counterparts and to explore whether resveratrol exerts its anti-medulloblastoma effects via regulating SIRT1 expression and bioactivity. Methods: The expression of SIRT1 in medulloblastoma and non-cancerous counterparts was elucidated by immunohistochemical ataining (IHC). To clarify the function of SIRT1 in medulloblastomas, SIRT1 expression in UW228-3 medulloblastoma cells were suppressed by RNA interference (RNAi). The influence of resveratrol in SIRT1 expressions in UW228-3 cells was analyzed by reverse transcription-polymerase chain reaction (RT-PCR), immunocytochemistry (ICC) and Western blotting (WB). The catalytic activity of deacetylase SIRT1 was examined by measuring the acetylation of the main substrate p53. Results: IHC staining revealed that SIRT1 was expressed in 64.17% of MB tissues, which was higher than that in noncancerous cerebellum tissues (14.29%). The frequencies of SIRT1 expression in the nodular MB (22.22%) with better prognosis is lower than that in anaplastic MB (79.07% ) and classic MB (60.29 %; P<0.05). The proliferation of UW228-3 cells was remarkably suppressed after being transfected with SIRT1 siRNA, accompanied with extensive cell death. The results of RT-PCR and WB showed that after 48 hours 100 M resveratrol treatment, SIRT1 expression in UW228-3 cells was down-regulated at both transcriptional and translational levels. However, resveratrol has no effect on the deacetylase activity of SIRT1. Conclusion: The above findings suggested that SIRT1 expression is corrected with the formation and prognosis of human MB. Resveratrol influences SIRT1 functioning in human MB cells through inhibiting SIRT1 expression rather than modulating its acetylation activity.