RORα-GABP-TFAM axis alleviates myosteatosis with fatty atrophy through reinforcement of mitochondrial capacity.

BACKGROUND: Fat infiltration in muscle, called 'myosteatosis', precedes muscle atrophy, which subsequently results in sarcopenia. Myosteatosis is frequently observed in patients with nonalcoholic fatty liver disease (NAFLD). We have previously reported that retinoic acid receptor-related orphan receptor-α (RORα) regulates mitochondrial dynamics and mitophagy in hepatocytes, resulting in an alleviation of NAFLD. In this study, we aimed to investigate the role of RORα in skeletal muscle and to understand molecular mechanisms by which RORα controls mitochondrial capacity, using an NAFLD-associated myosteatosis mouse model. METHODS: To establish a myosteatosis model, 7-week-old C57BL/6N mice were fed with high-fat diet (HFD). After 15 weeks of diet feeding, an adeno-associated virus vector encoding RORα (AAV-RORα) was injected to gastrocnemius (GA) muscles, or after 7 weeks of HFD feeding, JC1-40, an RORα agonistic ligand, was administered daily at a dose of 5 mg/kg/day by oral gavage for 5 weeks. Histological, biochemical and molecular analyses in various in vivo and in vitro experiments were performed. RESULTS: First, the number of oxidative MyHC2a fibres with intensive lipid infiltration increased by 3.8-fold in the red region of the GA of mice with myosteatosis (P < 0.001). RORα was expressed around MyHC2a fibres, and its level increased by 2.7-fold after HFD feeding (P < 0.01). Second, treatment of RORα ligands in C2C12 myoblasts, such as cholesterol sulfate and JC1-40, enhanced the number of oxidative fibres stained for MyHC1 and MyHC2a by two-fold to four-fold (P < 0.01), while it reduced the lipid levels in MyHC2a fibres by 20-50% (P < 0.001) in the presence of palmitic acids. Third, mitochondrial membrane potential (P < 0.01) and total area of mitochondria (P < 0.01) were enhanced by treatment of these ligands. Chromatin immunoprecipitation analysis showed that RORα bound the promoter of GA-binding protein α subunit gene that led to activation of mitochondrial transcription factor A (TFAM) in C2C12 myoblasts (P < 0.05). Finally, intramuscular transduction of AAV-RORα alleviated the HFD-induced myosteatosis with fatty atrophy; lipid contents in MyHC2a fibres decreased by 48% (P < 0.001), whereas the number of MyHC2b fibre increased by 22% (P < 0.001). Also, administration of JC1-40 improved the signs of myosteatosis in that it decreased the level of adipose differentiation-related protein (P < 0.01) but increased mitochondrial proteins such as cytochrome c oxidase 4 and TFAM in GA muscle (P < 0.01). CONCLUSIONS: RORα plays a versatile role in regulating the quantity of mitochondria and the oxidative capacity, ultimately leading to an improvement in myosteatosis symptoms.

HOMER3 promotes non-small cell lung cancer growth and metastasis primarily through GABPB1-mediated mitochondrial metabolism.

Cancer metabolism has emerged as a major target for cancer therapy, while the state of mitochondrial drugs has remained largely unexplored, partly due to an inadequate understanding of various mitochondrial functions in tumor contexts. Here, we report that HOMER3 is highly expressed in non-small cell lung cancer (NSCLC) and is closely correlated with poor prognosis. Lung cancer cells with low levels of HOMER3 are found to show significant mitochondrial dysfunction, thereby suppressing their proliferation and metastasis in vivo and in vitro. At the mechanistic level, we demonstrate that HOMER3 and platelet-activating factor acetylhydrolase 1b catalytic subunit 3 cooperate to upregulate the level of GA-binding protein subunit beta-1 (GABPB1), a key transcription factor involved in mitochondrial biogenesis, to control mitochondrial inner membrane genes and mitochondrial function. Concurrently, low levels of HOMER3 and its downstream target GABPB1 led to mitochondrial dysfunction and decreased proliferation and invasive activity of lung cancer cells, which raises the possibility that targeting mitochondrial synthesis is an important and promising therapeutic approach for NSCLC.

Prohibitin2/PHB2, Transcriptionally Regulated by GABPA, Inhibits Cell Growth via PRKN/Parkin-dependent Mitophagy in Endometriosis.

Endometriosis (EMS) is a common benign gynecological disease affecting women of reproductive age. It is characterized by abnormal growth of endometrial tissue outside the uterine cavity, resulting in chronic pelvic pain and infertility. Endometrial physiological and pathological processes are intimately connected to autophagy. Mitophagy is an essential selective mode that protects cells from metabolic stress and hypoxia. Mitochondrial autophagy mediated by prohibitin 2 (PHB2) is dependent on the PRKN/Parkin pathway and is involved in numerous human diseases. Uncertainty remains as to whether mitophagy regulation by PHB2 contributes to the occurrence and progression of EMS. This study aims to investigate the mechanism underlying the role of PHB2 in EMS. This study detected the protein and mRNA expression of PHB2 in ectopic and normal endometrial tissues of ovarian EMS, in addition to ectopic endometrial cell line 12Z and endometrial stromal cell line KC02-44D for gene overexpression or knockdown. Cell function experiments and mitochondrial function experiments were conducted to investigate the role of PHB2 in the endometrium. Bioinformatic analysis and experiments were also used to investigate the upstream transcription factors that influence PHB2 expression. PHB2 was downregulated in ectopic endometrium, and PHB2 overexpression inhibited cell proliferation, migration, and invasion and promoted apoptosis. The upregulation of mitophagy markers, including Parkin and LC3II/I, and the downregulation of autophagy degradation markers P62 and TOMM20 in EMS suggest that PHB2 may contribute to cell proliferation, migration, invasion, and apoptosis via PRKN/Parkin-mediated mitophagy. Analysis and validation of bioinformatics data revealed that the transcription factor GABPA binds directly to the PHB2 promoter region and controls the transcriptional expression of PHB2. This study investigated the role of PHB2 in the onset of EMS. It inhibits EMS growth via PRKN/Parkin-mediated mitophagy, and GABPA controls the transcriptional disorder of PHB2. This study's findings suggest a novel method for investigating the clinical potential of PHB2 in EMS.

Hyperpolarized δ-[1- 13C]gluconolactone imaging visualizes response to TERT or GABPB1 targeting therapy for glioblastoma.

TERT promoter mutations are a hallmark of glioblastoma (GBM). Accordingly, TERT and GABPB1, a subunit of the upstream mutant TERT promoter transcription factor GABP, are being considered as promising therapeutic targets in GBM. We recently reported that the expression of TERT or GABP1 modulates flux via the pentose phosphate pathway (PPP). Here, we investigated whether 13C magnetic resonance spectroscopy (MRS) of hyperpolarized (HP) δ- [1-13C]gluconolactone can serve to image the reduction in PPP flux following TERT or GABPB1 silencing. We investigated two different human GBM cell lines stably expressing shRNAs targeting TERT or GABPB1, as well as doxycycline-inducible shTERT or shGABPB1cells. MRS studies were performed on live cells and in vivo tumors, and dynamic sets of 13C MR spectra were acquired following injection of HP δ-[1-13C]gluconolactone. HP 6-phosphogluconolactone (6PG), the product of δ-[1-13C]gluconolactone via the PPP, was significantly reduced in TERT or GABPB1-silenced cells or tumors compared to controls in all our models. Furthermore, a positive correlation between TERT expression and 6PG levels was observed. Our data indicate that HP δ-[1-13C]gluconolactone, an imaging tool with translational potential, could serve to monitor TERT expression and its silencing with therapies that target either TERT or GABPB1 in mutant TERT promoter GBM patients.

LncRNA GABPB1-IT1 inhibits the tumorigenesis of renal cancer via the miR-21/PTEN axis.

Long noncoding RNA (lncRNA) (GABPB1-IT1) has been reported to be downregulated in lung cancer, while its expression and function in other cancers are unknown. In this study, the expression levels of GABPB1-IT1 in tissue samples from 62 ccRCC patients were measured by performing RT-qPCR. Potential base pairing formed between GABPB1-IT1 and miR-21 was explored using the online program IntaRNA 2.0 and further confirmed by Dual-luciferase activity assay and RNA pulldown assay. The role of GABPB1-IT1 and miR-21 in regulating the expression of PTEN was evaluated by RT-qPCR and Western blot. The role of GABPB1-IT1, miR-21, and PTEN in regulating the proliferation of Caki-2 cells was explored by CCK-8 assay. It was observed that GABPB1-IT1 was downregulated in ccRCC and predicted poor survival. GABPB1-IT1 directly interacted with miR-21, while it did not regulate the expression of each other. Moreover, upregulation of PTEN, which is a target of miR-21, was observed in ccRCC cells with overexpression of GABPB1-IT1. Overexpression of GABPB1-IT1 and PTEN decreased the proliferation rates of ccRCC cells. In addition, overexpression of GABPB1-IT1 reduced the enhancing effects of miR-21 on cell proliferation. Therefore, GABPB1-IT1 may upregulate PTEN by sponging miR-21 in ccRCC to inhibit cancer cell proliferation. Our study characterized a novel GABPB1-IT1/miR-21/PTEN axis in ccRCC.

GABP couples oncogene signaling to telomere regulation in TERT promoter mutant cancer.

Telomerase activation counteracts senescence and telomere erosion caused by uncontrolled proliferation. Epidermal growth factor receptor (EGFR) amplification drives proliferation while telomerase reverse transcriptase promoter (TERTp) mutations underlie telomerase reactivation through recruitment of GA-binding protein (GABP). EGFR amplification and TERTp mutations typically co-occur in glioblastoma, the most common and aggressive primary brain tumor. To determine if these two frequent alterations driving proliferation and immortality are functionally connected, we combine analyses of copy number, mRNA, and protein data from tumor tissue with pharmacologic and genetic perturbations. We demonstrate that proliferation arrest decreases TERT expression in a GABP-dependent manner and elucidate a critical proliferation-to-immortality pathway from EGFR to TERT expression selectively from the mutant TERTp through activation of AMP-mediated kinase (AMPK) and GABP upregulation. EGFR-AMPK signaling promotes telomerase activity and maintains telomere length. These results define how the tumor cell immortality mechanism keeps pace with persistent oncogene signaling and cell cycling.

Up-Regulation of RACGAP1 Promotes Progressions of Hepatocellular Carcinoma Regulated by GABPA via PI3K/AKT Pathway.

Hepatocellular carcinoma (HCC) is one of the dominating tumors causing death due to lack of timely discovery and valid treatment. Abnormal increase of Rac GTPase activating protein 1 (RACGAP1) has been verified to be an oncogene in plenty tumors. The profound mechanism of RACGAP1 was rarely reported in HCC. In this study, we explored the function and mechanism of RACGAP1 in HCC through multiple analysis and experiments. RACGAP1 expression was up-regulated in HCC samples and the high expression of RACGAP1 was an independent prognostic risk factor for HCC patients. Meanwhile, RACGAP1 promoted developments of HCC both in vitro and in vivo. We verified that RACGAP1 promoted proliferation of HCC via PI3K/AKT/CDK2 and PI3K/AKT/GSK3ß/Cyclin D1 signaling pathway. RACGAP1 accelerated the invasion and metastasis of HCC via phosphorylation of GSK3ß and nuclear translocation of ß-catenin. Furthermore, by luciferase reporter assay and Chromatin immunoprecipitation (ChIP) assay, we confirmed Recombinant GA Binding Protein Transcription Factor Alpha (GABPA) regulated the transcription of RACGAP1. All these findings revealed that RACGAP1 promotes the progression of HCC through a novel mechanism, which might be a new therapeutic target for HCC patients.

Galangin mitigates DOX-induced cognitive impairment in rats: Implication of NOX-1/Nrf-2/HMGB1/TLR4 and TNF-α/MAPKs/RIPK/MLKL/BDNF.

The cognitive and behavioral decline observed in cancer survivors who underwent doxorubicin (DOX)-based treatment raises the need for therapeutic interventions to counteract these complications. Galangin (GAL) is a flavonoid-based phytochemical with pronounced protective effects in various neurological disorders. However, its impact on DOX-provoked neurotoxicity has not been clarified. Hence, the current investigation aimed to explore the ability of GAL to ameliorate DOX-provoked chemo-brain in rats. DOX (2 mg/kg, once/week, i.p.) and GAL (50 mg/kg, 5 times/week., via gavage) were administered for four successive weeks. The MWM and EPM tests were used to evaluate memory disruption and anxiety-like behavior, respectively. Meanwhile, targeted biochemical markers and molecular signals were examined by the aid of ELISA, Western blotting, and immune-histochemistry. In contrast to DOX-impaired rats, GAL effectively preserved hippocampal neurons, improved cognitive/behavioral functions, and enhanced the expression of the cell repair/growth index, BDNF. The antioxidant feature of GAL was confirmed by the amelioration of MDA, NO and NOX-1, along with restoring the Nrf-2/HO-1/GSH cue. In addition, GAL displayed marked anti-inflammatory properties as verified by the suppression of the HMGB1/TLR4 nexus and p-NF-κB p65 to inhibit TNF-α, IL-6, IL-1ß, and iNOS. This inhibitory impact extended to entail astrocyte activation, as evidenced by the diminution of GFAP. These beneficial effects were associated with a notable reduction in p-p38MAPK, p-JNK1/2, and p-ERK1/2, as well as the necroptosis cascade p-RIPK1/p-RIPK3/p-MLKL. Together, these pleiotropic protective impacts advocate the concurrent use of GAL as an adjuvant agent for managing DOX-driven neurodegeneration and cognitive/behavioral deficits. DATA AVAILABILITY: The authors confirm that all relevant data are included in the supplementary materials.

Pharmacological mechanism of xanthoangelol underlying Nrf-2/TRPV1 and anti-apoptotic pathway against scopolamine-induced amnesia in mice.

Alzheimer's disease (AD) is a well-known type of age-related dementia. The present study was conducted to investigate the effect of xanthoangelol against memory deficit and neurodegeneration associated with AD. Preliminarily, xanthoangelol produced neuroprotective effect against H2O2-induced HT-22 cells. Furthermore, effect of xanthoangelol against scopolamine-induced amnesia in mice was determined by intraperitoneally (i.p.) administering xanthoangelol (1, 10 and 20 mg/kg), 30 min prior to induction. Mice were administered scopolamine at a concentration of 1 mg/kg; i.p. for the induction of amnesia associated with AD. Xanthoangelol dose dependently reduced the symptoms of Alzheimer's disease as observed by the results obtained from the behavioral analysis performed using Morris water maze and Y-maze test. The immunohistochemical analysis suggested that xanthoangelol significantly improved Keap-1/Nrf-2 signaling pathway. It greatly reduced the effects of oxidative stress and showed improvement in the anti-oxidant enzyme such as GSH, GST, SOD and catalase. Additionally, xanthoangelol decreased the expression of transient receptor potential vanilloid 1 (TRPV-1), a nonselective cation channel, involved in synaptic plasticity and memory. It activated the anti-oxidants and attenuated the apoptotic (Bax/Bcl-2) pathway. Xanthoangelol also significantly attenuated the scopolamine-induced neuroinflammation by the inhibition of interleukin-1 beta (IL-1ß), and tumor necrosis factor-α (TNF-α) levels. The histological analysis, showed a significant reduction in amyloid plaques by xanthoangelol. Therefore, the present study indicated that xanthoangelol has the ability to ameliorate the AD symptoms by attenuating neuroinflammation and neurodegeneration induced by scopolamine.

GABPA-activated TGFBR2 transcription inhibits aggressiveness but is epigenetically erased by oncometabolites in renal cell carcinoma.

BACKGROUND: The ETS transcription factor GABPA has long been thought of as an oncogenic factor and recently suggested as a target for cancer therapy due to its critical effect on telomerase activation, but the role of GABPA in clear cell renal cell carcinoma (ccRCC) is unclear. In addition, ccRCC is characterized by metabolic reprograming with aberrant accumulation of L-2-hydroxyglurate (L-2HG), an oncometabolite that has been shown to promote ccRCC development and progression by inducing DNA methylation, however, its downstream effectors remain poorly defined. METHODS: siRNAs and expression vectors were used to manipulate the expression of GABPA and other factors and to determine cellular/molecular and phenotypic alterations. RNA sequencing and ChIP assays were performed to identify GABPA target genes. A human ccRCC xenograft model in mice was used to evaluate the effect of GABPA overexpression on in vivo tumorigenesis and metastasis. ccRCC cells were incubated with L-2-HG to analyze GABPA expression and methylation. We carried out immunohistochemistry on patient specimens and TCGA dataset analyses to assess the effect of GABPA on ccRCC survival. RESULTS: GABPA depletion, although inhibiting telomerase expression, robustly enhanced proliferation, invasion and stemness of ccRCC cells, whereas GABPA overexpression exhibited opposite effects, strongly inhibiting in vivo metastasis and carcinogenesis. TGFBR2 was identified as the GABPA target gene through which GABPA governed the TGFß signaling to dictate ccRCC phenotypes. GABPA and TGFBR2 phenocopies each other in ccRCC cells. Higher GABPA or TGFBR2 expression predicted longer survival in patients with ccRCC. Incubation of ccRCC cells with L-2-HG mimics GABPA-knockdown-mediated phenotypic alterations. L-2-HG silenced the expression of GABPA in ccRCC cells by increasing its methylation. CONCLUSIONS: GABPA acts as a tumor suppressor by stimulating TGFBR2 expression and TGFß signaling, while L-2-HG epigenetically inhibits GABPA expression, disrupting the GABPA-TGFß loop to drive ccRCC aggressiveness. These results exemplify how oncometabolites erase tumor suppressive function for cancer development/progression. Restoring GABPA expression using DNA methylation inhibitors or other approaches, rather than targeting it, may be a novel strategy for ccRCC therapy.

Imaging biomarkers of TERT or GABPB1 silencing in TERT-positive glioblastoma.

BACKGROUND: TERT promoter mutations are observed in 80% of wild-type IDH glioblastoma (GBM). Moreover, the upstream TERT transcription factor GABPB1 was recently identified as a cancer-specific therapeutic target for tumors harboring a TERT promoter mutation. In that context, noninvasive imaging biomarkers are needed for the detection of TERT modulation. METHODS: Multiple GBM models were investigated as cells and in vivo tumors and the impact of TERT silencing, either directly or by targeting GABPB1, was determined using 1H and hyperpolarized 13C magnetic resonance spectroscopy (MRS). Changes in associated metabolic enzymes were also investigated. RESULTS: 1H-MRS revealed that lactate and glutathione (GSH) were the most significantly altered metabolites when either TERT or GABPB1 was silenced, and lactate and GSH levels were correlated with cellular TERT expression. Consistent with the drop in lactate, 13C-MRS showed that hyperpolarized [1-13C]lactate production from [1-13C]pyruvate was also reduced when TERT was silenced. Mechanistically, the reduction in GSH was associated with a reduction in pentose phosphate pathway flux, reduced activity of glucose-6-phosphate dehydrogenase, and reduced NADPH. The drop in lactate and hyperpolarized lactate were associated with reductions in glycolytic flux, NADH, and expression/activity of GLUT1, monocarboxylate transporters, and lactate dehydrogenase A. CONCLUSIONS: Our study indicates that MRS-detectable GSH, lactate, and lactate production could serve as metabolic biomarkers of response to emerging TERT-targeted therapies for GBM with activating TERT promoter mutations. Importantly these biomarkers are readily translatable to the clinic, and thus could ultimately improve GBM patient management.

Association of single nucleotide polymorphisms in the nuclear respiratory factor-2 beta subunit-encoding the GABPB1 gene within the occupational environment.

GABPB1, known as nuclear respiratory factor 2 (Nrf2), activates the mitochondrial genes that are responsible for antioxidant action and detoxification. Two single nucleotide polymorphisms (SNPs) of GABPB1, such as rs7181866 and rs8031031, were reported to be associated with the prevention of the increasing cancer risk caused by environmental deterioration. Between March 1 and May 1, 2018, human peripheral blood mononuclear cells (PBMCs) from a cohort of 300 volunteers working in adverse occupational environments were genotyped for the two SNPs in the present study. The SNP rs7181866 was found to be significantly greater in the male group than in the female group. Frequencies of SNP rs7181866 and bi-allele SNPs (rs7181866 + rs8031031) were significantly different between the <35-year-old group and the ≥35-year-old group. Further, multinomial logistic regression analysis of the occupational environments revealed the highest predictive frequency of SNPs for four environmental factors, of which chemical factors accounted for 15.33% rs7181866, physical factors accounted for 34.79% rs7181866 + rs8031031, physical + chemical factors accounted for 39.5% rs8031031, and unknown factors accounted for 26.5% rs7181866 + rs8031031. In conclusion, the G allele of rs7181866 was found to be significantly more susceptible than the rs8031031 allele under adverse occupational environmental factors, and physical factors such as noise, which appear to play vital roles in causing SNP mutations.

6-Shogaol protects against isoproterenol-induced cardiac injury in rats through attenutating oxidative stress, inflammation, apoptosis and activating nuclear respiratory factor-2/heme oxygenase-1 signaling pathway.

The current study investigated the preventive effect of 6-Shogaol on isoproterenol hydrochloride (ISO)-induced myocardial cardiac injury. 6-Shogaol (50 mg/kg b.w.) was administered for 14 days at pretreatment and ISO-induction (85 mg/kg b.w.) for the last two days (13th and 14th days) by subcutaneous injection. Cardiac markers in serum like creatine kinase (CK), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), cardiac troponins T (cTn T) and I (cTn I) increased in ISO-induced rats. Moreover, lipid peroxidative markers like thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LOOH) were raised, and the activities/level of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH) were diminished in ISO-treated heart tissue. In addition, inflammatory and nuclear respiratory factor (Nrf)-2 signalling molecules were upregulated in ISO-induced ischemic rats. 6-Shogaol pretreatment decreased the activities of cardiac and lipid peroxidative markers and enhanced the antioxidant status in ISO-induced cardiac injury rats. Further, 6-Shogaol pretreatment inhibited serum inflammatory markers: tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), nuclear factor-kappaB (NF-κB), Nrf-2 molecule and heme oxygenase (HO)-1 in ISO-induced cardial damage rats. We noticed the effect of 6-Shogaol inhibited pro-apoptotic genes like B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax), Fas, caspase-3, -8, -9, cytochrome C, and inflammatory genes and increased Bcl-2 expression in ISO-treated rats. The cardioprotective activity of 6-Shogaol in rats with ISO-induced myocardial damage may be due to its ability to reduce oxidative stress, inflammation, and apoptosis, perhaps via the Nrf-2/HO-1 signalling pathway.

GABPA Expression in Endometrial Carcinoma: A Prognostic Marker.

BACKGROUND: GA-binding protein A (GABPA), a transcription factor, is broadly involved in physiological and pathological processes. Several studies have investigated the relationship between GABPA expression level and outcomes of various malignancies. However, the function and clinicopathological significance of GABPA in endometrial carcinoma (EC) remain obscure. METHODS: The GABPA mRNA expression in EC tissues and adjacent nonneoplastic tissues in the TCGA database was involved in our study. The protein expression of GABPA in 107 EC tissues and 15 normal endometrial tissues was detected by immunohistochemistry. RESULTS: The GABPA expression was significantly downregulated in EC tissues compared with its expression in normal tissues (P < 0.001). The expression of GABPA was markedly correlated with type II EC (P < 0.01) and grade 3 EC (P < 0.05). A tendency has been observed that patients with low GABPA levels had relatively poorer overall survival (OS) (P = 0.036) and disease-free survival (DFS) (P = 0.016) than patients with high GABPA levels. The multivariate Cox proportional hazard model showed that lower expression of GABPA was an independent poor prognostic factor for OS (P = 0.043) and DFS (P = 0.045). Similar correlation between low expression levels of GABPA and unfavorable prognosis has also been found in type II or grade 3 EC. IHC analysis showed EC tissues had low expression of GABPA, which indicated relatively poor prognosis. Moreover, we identified that the GABPA mRNA expression was negatively correlated with its methylation level (R = -0.2512, P < 0.001) which is one of the mechanisms for the silencing of GABPA gene. CONCLUSION: GABPA may act as an independent predictor of clinical prognosis and serve as a potential target gene for EC therapy.

Differential long non-coding RNA expression profile and function analysis in primary Sjogren's syndrome.

BACKGROUND: Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease characterized by abnormal immune cell activation. This study aimed to investigate differentially expressed long non-coding RNA (lncRNA) in peripheral blood mononuclear cells (PBMCs) in patients with pSS to identify lncRNAs that affect pSS pathogenesis. METHODS: Total RNA was extrated from PBMCs of 30 patients with pSS and 15 healthy persons. Transcriptome sequencing was used to screen differentially expressed lncRNAs and mRNAs in 8 RNA samples from the discovery cohort. The differentially expressed mRNAs underwent functional enrichment analysis. A protein interaction relationship (PPI) and competitive endogenous RNA (ceRNA) network was constructed. Real-time PCR was used to validate screened lncRNAs in all 45 RNA samples.. RESULTS: 1180 lncRNAs and 640 mRNAs were differentially expressed in pSS patients (fold change > 2 in healthy persons). The PPI network was constructed with 640 mRNAs and a ceRNA network with four key lncRNAs (GABPB1-AS1, PSMA3-AS1, LINC00847 and SNHG1). Real-time PCR revealed that GABPB1-AS1 and PSMA3-AS1 were significantly up-regulated 3.0- and 1.4-fold in the pSS group, respectively. The GABPB1-AS1 expression level was positively correlated with the percentage of B cells and IgG levels. CONCLUSIONS: GABPB1-AS1 was significently up-regulated in pSS patients, and its expression level is positively correlated with the percentage of B cells and IgG levels. GABPB1-AS1 may be involved in the pathogenesis of pSS and may be a promising biological marker.

Therapeutic targeting of FOS in mutant TERT cancers through removing TERT suppression of apoptosis via regulating survivin and TRAIL-R2.

The telomerase reverse transcriptase (TERT) has long been pursued as a direct therapeutic target in human cancer, which is currently hindered by the lack of effective specific inhibitors of TERT. The FOS/GABPB/(mutant) TERT cascade plays a critical role in the regulation of mutant TERT, in which FOS acts as a transcriptional factor for GABPB to up-regulate the expression of GABPB, which in turn activates mutant but not wild-type TERT promoter, driving TERT-promoted oncogenesis. In the present study, we demonstrated that inhibiting this cascade by targeting FOS using FOS inhibitor T-5224 suppressed mutant TERT cancer cells and tumors by inducing robust cell apoptosis; these did not occur in wild-type TERT cells and tumors. Mechanistically, among 35 apoptotic cascade-related proteins tested, the apoptosis induced in this process specifically involved the transcriptional activation of tumor necrosis factor-related apoptosis-inducing ligand receptor 2 (TRAIL-R2) and inactivation of survivin, two key players in the apoptotic cascade, which normally initiate and suppress the apoptotic cascade, respectively. These findings with suppression of FOS were reproduced by direct knockdown of TERT and prevented by prior knockdown of TRAIL-R2. Further experiments demonstrated that TERT acted as a direct transcriptional factor of survivin, up-regulating its expression. Thus, this study identifies a therapeutic strategy for TERT promoter mutation-driven cancers by targeting FOS in the FOS/GABPB/(mutant) TERT cascade, circumventing the current challenge in pharmacologically directly targeting TERT itself. This study also uncovers a mechanism through which TERT controls cell apoptosis by transcriptionally regulating two key players in the apoptotic cascade.

Cancer-specific loss of TERT activation sensitizes glioblastoma to DNA damage.

Most glioblastomas (GBMs) achieve cellular immortality by acquiring a mutation in the telomerase reverse transcriptase (TERT) promoter. TERT promoter mutations create a binding site for a GA binding protein (GABP) transcription factor complex, whose assembly at the promoter is associated with TERT reactivation and telomere maintenance. Here, we demonstrate increased binding of a specific GABPB1L-isoform-containing complex to the mutant TERT promoter. Furthermore, we find that TERT promoter mutant GBM cells, unlike wild-type cells, exhibit a critical near-term dependence on GABPB1L for proliferation, notably also posttumor establishment in vivo. Up-regulation of the protein paralogue GABPB2, which is normally expressed at very low levels, can rescue this dependence. More importantly, when combined with frontline temozolomide (TMZ) chemotherapy, inducible GABPB1L knockdown and the associated TERT reduction led to an impaired DNA damage response that resulted in profoundly reduced growth of intracranial GBM tumors. Together, these findings provide insights into the mechanism of cancer-specific TERT regulation, uncover rapid effects of GABPB1L-mediated TERT suppression in GBM maintenance, and establish GABPB1L inhibition in combination with chemotherapy as a therapeutic strategy for TERT promoter mutant GBM.

GABPB1-AS1 acts as a tumor suppressor and inhibits non-small cell lung cancer progression by targeting miRNA-566/F-box protein 47.

It has been certified that GABPB1-AS1 is aberrantly expressed and plays as a vital role in some kinds of cancers. However, its expression pattern and functions in non-small cell lung cancer (NSCLC) are still largely unknown. This study aims to assess GABPB1-AS1 expression and biological roles in NSCLC. The expression of GABPB1-AS1 was detected in NSCLC specimens and adjacent normal specimens. CCK8 and Transwell assays were performed to evaluate the effects of GABPB1-AS1 on NSCLC cell proliferation, migration and invasion. Bioinformatics tools and luciferase reporter assays were applied to predict and verify GABPB1-AS1's direct targets. The results revealed that GABPB1-AS1 is sharply reduced in NSCLC specimens and cell lines. CCK8 assays indicated that overexpression of GABPB1-AS1 dramatically reduced NSCLC cell growth, and Transwell assays proved that NSCLC cell migration and invasion were distinctly inhibited by GABPB1-AS1. Exploration of the mechanism uncovered that miRNA-566 (miR-566)/F-box protein 47 (FBXO47) is directly targeted by GABPB1-AS1 in NSCLC. The study demonstrated that GABPB1-AS1 inhibited NSCLC cell proliferation, migration and invasion by targeting miR-566/FBXO47.

Association study of performance-related polymorphisms in Brazilian combat-sport athletes highlights variants in the GABPB1 gene.

Combat sports are an intermittent sport, with mixed anaerobic and aerobic energy production. Here, we investigated whether the polymorphisms that have been previously suggested as genetic markers for endurance or power phenotypes were associated with combat-sport athletic status. A total of 23 previously reported performance-related polymorphisms were examined in a cohort of 1,129 Brazilian individuals (164 combat-sport athletes and 965 controls), using a case-control association study. We found that the GA-binding protein transcription factor subunit beta 1 (GABPß1) gene (also known as nuclear respiratory factor 2; NRF2) was associated with athletic status, with the minor G (rs7181866) and T (rs8031031) alleles overrepresented in athletes (P ≤ 0.003), especially among world-class athletes (P ≤ 0.0002). These findings indicate that single-nucleotide polymorphisms (SNPs) within the GABPß1 gene increase the likelihood of an individual being a combat-sport athlete, possibly because of a better mitochondrial response to intermittent exercises.