Bax Promoter Research Articles

In silico study of lactoferrin as an anticancer, anti-viral, and anti-bacterial bioactive compound and disease diagnostic marker.

Studying the interaction of proteins and genes by current computational methods is effective in new drug design. Considering the special role of lactoferrin (Lf) identifying its action mechanism is a new gate to the targeted treatment of some diseases. This study aimed to investigate the molecular interaction of Lf with virus spike, the bacterial cell binding receptor, and the proteins involved in apoptosis by in silico research. The docking results showed that the amino acids involved in the interaction between the spike virus of COVID-19 with the ACE2 receptor were similar to the amino acids in the interaction between the virus spike and Lf, and the binding between Lf and the viral spike was more inclined. The N-terminus of Lf interacted with the N-terminus region of the CD14, which contains the binding sites of bacterial lipopolysaccharide to the cell. Lf can compete for binding with bacterial lipopolysaccharides. The results related to the docking of TP53, BAX, and BAK1 gene promoters and Lf showed that Lf with one or more amino acids that are responsible for binding to DNA interacted with TP53 and BAX genes with higher binding affinity. In all protein and protein-gene interactions, the N-lobe region of Lf, which is its functional region, is involved in these interactions, and the anticancer, antibacterial, and antiviral, roles of Lf are related to this region. Lf is important as a medicinal supplement for treating COVID-19 and cancer.

The expression and role of SUZ12 in lung adenocarcinoma.

SUZ12 is one of the core members of the polycomb repressive complex 2 (PRC2), but its expression and role in lung adenocarcinoma (LUAD) are unclear. We aimed to explore the expression, prognosis, biological functions and roles of SUZ12 in LUAD. The expression of SUZ12 was detected by immunohistochemical staining, qRT-PCR, and western blotting in LUAD tissues and cells. The biological functions and molecular mechanisms of SUZ12 were characterized by a range of invitro and invivo experiments. SUZ12 was overexpressed in LUAD tissues, and high SUZ12 expression was correlated with worse clinicopathological features and a poorer prognosis. Knockdown of SUZ12 significantly inhibited cell growth, colony formation, invasion, and migration, and induced apoptosis and G1/S phase arrest, while overexpression of SUZ12 had the opposite effects. Knockdown of SUZ12 decreased the tumorigenic capacity of A549 cells invivo. The expression of key signaling molecules related to the cell cycle, apoptosis, migration, and immunity were altered by the knockdown or overexpression of SUZ12. SUZ12 can directly bind to the Bax promoter region, EZH2 and H3K27me3 levels dependents on SUZ12. The expression levels of SUZ12 and Bax were negatively correlated in LUAD tissues. SUZ12 is a new oncogene related to the poor prognosis of LUAD. SUZ12 regulates LUAD progression by regulating the expression of related signaling molecules, and as a part of the PRC2 complex, it may bind to the Bax promoter to silence Bax expression.

An iASPP‐derived short peptide restores p53‐mediated cell death in cancers with wild‐type p53

AbstractBackgroundInhibitor of apoptosis‐stimulating protein of p53 (iASPP) is an evolutionarily conserved p53 inhibitor. Mechanistically, iASPP can accelerate tumorigenesis by inhibiting the transactivation function of p53. Targeting the interaction between iASPP and p53 may be a potential therapy for restoring the activity of p53 in tumors.MethodsWe constructed an iASPP‐derived peptide, called A8, that was derived from the C‐terminus of iASPP. Here, we transfected A8 into two wild‐type (WT) p53 cell lines, U2OS and A549, and then determined the number of apoptotic cells. The mechanism by which A8 affected apoptosis was further examined by immunoprecipitation (IP), Dual‐Luciferase reporter assays, and chromatin IP assays. Real‐time polymerase chain reaction and western blots were also used to examine the expression levels of apoptosis‐related factors.ResultsOur data demonstrate that A8 can increase apoptosis rates in WT p53 cell lines. Functional analysis suggested that A8 restored the transcriptional function and DNA binding activities of p53 toward the Bax and PUMA gene promoters. Moreover, A8 reduced cell proliferation and inhibited tumor growth in xenograft nude mice.ConclusionsThese data provide a new approach for restoring the tumor suppressor function of p53 in cancer cells that express WT p53 and therefore may serve as a novel cancer treatment strategy.

Analysis of patients with colorectal cancer shows a specific increase in serum anti-ING1 autoantibody levels

Colorectal cancer (CRC) is the third most prevalent cancer in the world, yet the sensitivity and specificity of biomarkers for CRC diagnosis are insufficient. In the present study, we performed a protein microarray screening method to identify antibody markers for CRC. Inhibitor of growth family 1 (ING1) was identified as a candidate tumor antigen for CRC using protein microarrays (ProtoArray). Subsequent amplified luminescence proximity homogeneous assay-linked immunosorbent assay using recombinant ING1 protein showed that the serum levels of anti-ING1 antibodies were increased not only in patients with CRC but also in those with esophageal cancer (EC), gastric cancer (GC), breast cancer (BrC), and pancreatic cancer (PC) compared with those of healthy donors (HDs). Antibodies against the ING1 amino acids between 239 and 253 were present at significantly higher levels in patients with CRC than in those with EC, GC, BrC, or PC. Anti-ING1 antibody levels were significantly higher in the patients with CRC at any stages than in the HDs. Immunohistochemical staining revealed higher expression of ING1 protein in CRC cells than in the adjacent normal tissues. In luciferase reporter assays using a CRC cell line, ING1 augmented p53-mediated NOXA promoter activity but attenuated p53-stimulated Bax, p21, and PUMA promoter activities. Consequently, serum anti-ING1 antibodies can be used for sensitive and specific diagnoses of CRC.

HBV-upregulated Lnc-HUR1 inhibits the apoptosis of liver cancer cells

Lnc-HUR1 is an HBV-related long non-coding RNA, which can promote the proliferation of hepatoma cells and the occurrence and development of liver cancer. In this study we explored the effect of lnc-HUR1 on the apoptosis of hepatocellular carcinoma cells by taking the approach of immunoblotting, quantitative real time PCR, luciferase reporter assay, chromatin immunoprecipitation (ChIP) and flow cytometry. We found that overexpression of lnc-HUR1 significantly reduced the activity of caspase3/7 and the cleavage of PARP-1, while knocking down of lnc-HUR1 significantly increased the activity of caspase3/7 and promoted the cleavage of PARP-1 in HepG2 cells treated with TGF-β, pentafluorouracil or staurosporine. Consistently, the data from Annexin-V/PI staining showed that overexpression of lnc-HUR1 inhibited apoptosis, while knockdown of lnc-HUR1 promoted apoptosis. Moreover, overexpression of lnc-HUR1 up-regulated the apoptosis inhibitor Bcl-2 and down-regulated the pro-apoptotic factor BAX at both RNA and protein levels. In the CCL4-induced acute liver injury mice model, the expression of Bcl-2 in the liver tissue of lnc-HUR1 transgenic mice was higher than that of the control mice. The data from ChIP assay indicated that lnc-HUR1 reduced the enrichment of p53 on Bcl-2 and BAX promoters. All these results indicated that lnc-HUR1 inhibited the apoptosis by promoting the expression of apoptosis inhibitor Bcl-2 and inhibiting the expression of apoptosis promoting factor BAX. Further studies showed that lnc-HUR1 regulated the transcription of Bcl-2 and BAX in HCT116 cells, but had no effect on the expression of Bcl-2 and BAX in HCT116 p53-/- cells, indicating that lnc-HUR1 regulates the transcription of Bcl-2 and BAX dependent upon the activity of p53. In conclusion, HBV upregulated lnc-HUR1 can inhibit the apoptosis of hepatoma cells. Lnc-HUR1 inhibits apoptosis by inhibiting the transcriptional activity of p53. These results suggest that lnc-HUR1 plays an important role in the occurrence and development of HBV-related hepatocellular carcinoma.

Riluzole-induced apoptosis in osteosarcoma is mediated through Yes-associated protein upon phosphorylation by c-Abl Kinase

Our lab has previously demonstrated Riluzole to be an effective drug in inhibiting proliferation and inducing apoptosis in both human and mouse osteosarcoma. Yes-associated protein is a transcription co-activator, known to be involved in cell proliferation or apoptosis depending on its protein partner. In the present study we investigated the role of YAP in apoptosis in osteosarcoma, we hypothesized that YAP may be activated by Riluzole to induce apoptosis in osteosarcoma. By knocking down the expression of YAP, we have demonstrated that Riluzole failed to induce apoptosis in YAP deficient osteosarcoma cells. Riluzole caused translocation of YAP from the cytoplasm to the nucleus, indicating YAP’s role in apoptosis. Both Riluzole-induced phosphorylation of YAP at tyrosine 357 and Riluzole-induced apoptosis were blocked by inhibitors of c-Abl kinase. In addition, knockdown of c-Abl kinase prevented Riluzole-induced apoptosis in LM7 cells. We further demonstrated that Riluzole promoted interaction between YAP and p73, while c-Abl kinase inhibitors abolished the interaction. Subsequently, we demonstrated that Riluzole enhanced activity of the Bax promoter in a luciferase reporter assay and enhanced YAP/p73 binding on endogenous Bax promoter in a ChIP assay. Our data supports a novel mechanism in which Riluzole activates c-Abl kinase to regulate pro-apoptotic activity of YAP in osteosarcoma.

LncRNA GAS5, as a ceRNA, inhibits the proliferation of diffuse large B‑cell lymphoma cells by regulating the miR‑18a‑5p/RUNX1 axis.

Diffuse large B-cell lymphoma (DLBCL) is a common and fatal malignant tumor caused by B-lymphocytes. Long non-coding RNA (lncRNA) GAS5 (growth arrest specific 5) has been reported to function as a tumor suppressor gene, and is differentially expressed in DLBCL. The present study aimed to explore the potential mechanisms of action of lncRNA GAS5 in the proliferation of DLBCL cells. The expression levels of GAS5, miR-18a-5p and Runt-related transcription factor 1 (RUNX1) in DLBCL cell lines were detected using reverse transcription-quantitative polymerase chain reaction, and their effects on cell proliferation, the cell cycle and apoptosis were determined using 5-ethynyl-2′-deoxyuridine assay and flow cytometry. Dual-luciferase reporter and RNA pull-down assays were used to evaluate the interaction between GAS5 and miR-18a-5p, or between miR-18a-5p and RUNX1. Chromatin immunoprecipitation assay was used to identify the interaction between RUNX1 and BAX. The expression levels of GAS5 and RUNX1 were downregulated; however, miR-18a-5p expression was upregulated in the DLBCL cell lines compared with the normal controls. GAS5 directly interacted with miR-18a-5p by acting as a competing endogenous RNA (ceRNA) and reversed the low expression of RUNX1 induced by miR-18a-5p. Additionally, the knockdown of RUNX1 reversed the inhibitory effects of GAS5 on the proliferation and cell cycle G1 arrest, and its promoting effects on the apoptosis of OCI-Ly3 and TMD8 cells. Moreover, RUNX1 enhanced BAX expression by directly binding to the BAX promoter. On the whole, the present study demonstrates that GAS5 functions as a ceRNA, inhibiting DLBCL cell proliferation by sponging miR-18a-5p to upregulate RUNX1 expression. These findings may provide a potential therapeutic strategy for DLBCL.

Methylation of Promoters of Apoptosis-Related Genes in Blood Lymphocytes of Workers Exposed to Occupational External Irradiation.

We studied the effect of technogenic radiation on the degree of promoter methylation in genes involved in apoptosis in blood lymphocytes of workers exposed to long-term γ-radiation during their professional activities. Blood samples for the analysis were obtained from 11 conventionally healthy men aged from 54 to 71 years (mean 66 years), workers of the Siberian Group of Chemical Enterprises working experience from 27 to 40 years (mean 30 years); the external exposure dose was 175.88 mSv (158.20-207.81 mSv). In all examined subjects, the degree of methylation of the promoters of apoptosis-related genes ranged from 0.22 to 50.00%. A correlation was found between the degree of methylation of BCLAF1 promoters (p=0.035) with the age of workers, BAX promoters (p=0.0289) with high content of aberrant cells, and APAF1 promoters (p=0.0152) with increased number of dicentric chromosomes. A relationship was found between the dose of external irradiation and the degree of methylation of gene promoters of BAD (p=0.0388), BID (р=0.0426), and HRK (р=0.0101) genes.

P33ING1b regulates acetylation of p53 in oral squamous cell carcinoma via SIR2

BackgroundOral squamous cell carcinoma (OSCC), a form of head and neck squamous cell carcinoma (HNSCC) has a poor 5-year survival rate. OSCC patients are often treated with cisplatin but resistance to chemotherapy is often observed. This makes it important identification of alternative therapeutic targets which will result in more favorable outcome in OSCC patients. The plant homeodomain (PHD)-containing protein Inhibitor of Growth family of tumor suppressor proteins (p33ING1b) has been indicated as a tumor suppressor in different cancers including OSCC. This protein has been shown to function by modulating transcriptional activity of p53; however, the exact mechanism(s) are not well defined.MethodsExpression of total and acetylated p53 and p33ING1b protein was determined in OSCC cell lines YD-9, YD-8, and YD-38 by immunoblot analysis. Effect of modulation of p33ING1b protein expression on acetylation of p53 and cell proliferation was determined by immunoblot and MTT assay. Effect of modulation of p33ING1b protein expression on transactivation of p53 was assessed by heterologous promoter-based reporter and chromatin immunoprecipitation. Effect of modulation of expression of p33ING1b on SIR2 mRNA and protein was determined by quantitative real-time PCR and immunoblot analyses. Impact of modulation of p33ING1b alone or in combination with SIR2 on chemosensitivity of YD-9 and YD-8 cells to cisplatin was determined in time and dose-dependent cell proliferation assays.ResultsHere, using a panel of OSCC cell lines with wild type or mutant p53, we show that p33ING1b expression is correlated to acetylation of p53 at lysine 382 residue. Increased acetylation of p53 following overexpression of p33ING1b was associated with increased expression of the pro-apoptotic proteins BAX, p21, and cleaved-Caspase 3, and decreased cell proliferation. Reporter assays with p21 and BAX promoters showed that p33ING1b expression levels directly correlated to promoter activity of these 2 genes. Chromatin immunoprecipitation assay showed that transcriptional regulation of p21 and BAX by acetylated p53 is dependent on expression level of p33ING1b. Differential acetylation of p53 following modulation of p33ING1b expression was indirect. Expression of p33ING1b was found to be inversely correlated to the NAD-dependent deacetylase silent information regulator 2 (SIR2). SIR2 was transcriptionally regulated by p33ING1b. Relative expression of p33ING1b was found to dictate chemosensitivity of OSCC cell lines to cisplatin treatment. Concomitant overexpression of p33ING1b and knockdown of SIR2 had a synergistic effect on chemosensitivity of OSCC cell lines to cisplatin, compared to either overexpression of p33ING1b or knockdown of SIR2 alone.ConclusionsThe results from the current study thus elucidate that p33ING1b regulates p53 acetylation irrespective of p53 mutation and subsequent transactivation by transcriptional regulation of SIR2 expression. The results also indicate that p33ING1b and SIR2 are potentially attractive therapeutic targets.

Genetic and epigenetic analysis of the BAX and BCL2 in the placenta of pregnant women complicated by preeclampsia.

The current study examined the effects of BAX and BCL2 polymorphisms and methylation as well as mRNA expression on susceptibility to PE. After delivery, the placentas were collected from 92 women with PE, as well as 106 normotensive pregnant women. The BAX rs4645878 and BCL2 rs2279115 polymorphisms were genotyped by the PCR-RFLP method. Methylation-specific PCR (MSP) was used for analysis of promoter methylation. mRNA expression was assayed by Quantitative RT-PCR. In addition, in silico analysis was performed by bioinformatics tools. There was no relationship between PE and placental BAX rs4645878 and BCL2 rs2279115 polymorphisms. The groups were not significantly different regarding the promoter methylation of BAX gene. Nonetheless, the MM status of BCL2 promoter had a significantly higher frequency in the PE group and was associated with 2.7-fold higher risk of PE (OR=2.7, 95% CI=1.3-5.6; P = 0.01). The relative mRNA expression of BCL2 was decreased in the placentas of PE women (P < 0.0001). The expression of BAX gene was not significantly different between the two groups. There was no association between placental BAX rs4645878 and BCL2 rs2279115 polymorphisms and mRNA expression levels. In silico analysis indicated that BAX rs4645878 and BCL2 rs2279115 polymorphisms were located in the core recognition site of different transcription factors and these substitutions of wild allele resulted in the loss and/ or change of these binding sites and subsequently may alter BCL2 and BAX expression. This study showed that the BAX and BCL2 polymorphisms and BAX promoter methylation were not associated with PE risk. The BCL2 promoter methylation was associated with lower BCL2 expression and higher PE susceptibility.

Pseudolaric acid B inhibits PAX2 expression through Wnt signaling and induces BAX expression, therefore promoting apoptosis in HeLa cervical cancer cells.

ObjectivesPseudolaric acid B (PAB) has been shown to inhibit the growth of various tumor cells, but the molecular details of its function are still unknown. This study investigated the molecular mechanisms by which PAB induces apoptosis in HeLa cells.MethodsThe 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were performed to investigate the effect of PAB treatment in various cervical cancer cell lines. Annexin V/propidium iodide staining combined with flow cytometry and Hoechst 33258 staining were used to assess PAB-induced apoptosis. Additionally, we performed bioinformatics analyses and identified a paired box 2 (PAX2) binding site on the BAX promoter. We then validated the binding using luciferase and chromatin immunoprecipitation assays. Finally, western blotting assays were used to investigate PAB effect on the Wnt signaling and the involved signaling molecules.ResultsPAB promotes apoptosis and downregulates PAX2 expression in HeLa cells in a time- and concentration-dependent manner. PAX2 binds to the promoter of BAX and inhibits its expression; therefore, PAX2 inhibition is associated with increased levels of BAX, which induces apoptosis of HeLa cells via the mitochondrial pathway. Additionally, PAB inhibits classical Wnt signaling.ConclusionPAB effectively inhibits Wnt signaling and PAX2 expression, and increases BAX levels, which induce apoptosis in HeLa cells. Therefore, PAB is a promising natural molecule for the treatment of cervical cancer.

Apoptotic effect of resveratrol on human T-ALL cell line CCRF-CEM is unlikely exerted through alteration of BAX and BCL2 promoter methylation.

One of the fundamental barriers leading to failure of leukemia therapy is the resistance against conventional chemotherapies, common modality used to cure leukemia. Having the potential to trigger apoptosis in various human leukemia cell lines, resveratrol is regarded as a robust agent in chemotherapy regimens. The current study was aimed to assess whether the apoptotic effect of resveratrol on T-cellacute lymphoblastic leukemia cell line, CCRF-CEM, is exerted through DNA methylation of BAX and BCL2 gene promoters. For this purpose, the CCRF-CEM cells were treated by resveratrol under standard cell culture. To analyze the promoter DNA methylation changes, we used methylation-specific polymerase chain reaction technique following the resveratrol treatment at different dosages and time intervals. Based on our previous study, the resveratrol treatment can trigger apoptosis in CCRF-CEM cell line via upregulation of apoptotic BAX gene and downregulation of antiapoptotic BCL2 gene. Despite these alterations in gene expression, the current study reveals no changes in DNA methylation patterns of subjected genes following the resveratrol treatment. Unchanged status of DNA methylation of BAX and BCL2 genes may suggest that resveratrol causes the gene expression changes through a distinct mechanism which requires further studies to be understood.

Organophosphate pesticide chlorpyrifos impairs STAT1 signaling to induce dopaminergic neurotoxicity: Implications for mitochondria mediated oxidative stress signaling events

The organophosphate (OP) pesticide chlorpyrifos (CPF), used in agricultural settings, induces developmental and neurological impairments. Recent studies using in vitro cell culture models have reported CPF exposure to have a positive association with mitochondria-mediated oxidative stress response and dopaminergic cell death; however, the mechanism by which mitochondrial reactive oxygen species (ROS) contribute to dopaminergic cell death remains unclear. Therefore, we hypothesized that STAT1, a transcription factor, causes apoptotic dopaminergic cell death via mitochondria-mediated oxidative stress mechanisms. Here we show that exposure of dopaminergic neuronal cells such as N27 cells (immortalized murine mesencephalic dopaminergic cells) to CPF resulted in a dose-dependent increase in apoptotic cell death as measured by MTS assay and DNA fragmentation. Similar effects were observed in CPF-treated human dopaminergic neuronal cells (LUHMES cells), with an associated increase in mitochondrial dysfunction. Moreover, CPF (10 μM) induced time-dependent increase in STAT1 activation coincided with the collapse of mitochondrial transmembrane potential, increase in ROS generation, proteolytic cleavage of protein kinase C delta (PKCδ), inhibition of the mitochondrial basal oxygen consumption rate (OCR), with a concomitant reduction in ATP-linked OCR and reserve capacity, increase in Bax/Bcl-2 ratio and enhancement of autophagy. Additionally, by chromatin immunoprecipitation (ChIP), we demonstrated that STAT1 bound to a putative regulatory sequence in the NOX1 and Bax promoter regions in response to CPF in N27 cells. Interestingly, overexpression of non-phosphorylatable STAT1 mutants (STAT1Y701F and STAT1S727A) but not STAT1 WT construct attenuated the cleavage of PKCδ and ultimately cell death in CPF-treated cells. Furthermore, small interfering RNA knockdown demonstrated STAT1 to be a critical regulator of autophagy and mitochondria-mediated proapoptotic cell signaling events after CPF treatment in N27 cells. Finally, oral administration of CPF (5 mg/kg) in postnatal rats (PNDs 27–61) induced motor deficits, and nigrostriatal dopaminergic neurodegeneration with a concomitant induction of STAT1-dependent proapoptotic cell signaling events. Conversely, co-treatment with mitoapocynin (a mitochondrially-targeted antioxidant) and CPF rescued motor deficits, and restored dopaminergic neuronal survival via abrogation of STAT1-dependent proapoptotic cell signaling events. Taken together, our study identifies a novel mechanism by which STAT1 regulates mitochondria-mediated oxidative stress response, PKCδ activation and autophagy. In this context, the phosphorylation of Tyrosine 701 and Serine 727 in STAT1 was found to be essential for PKCδ cleavage. By attenuating mitochondrial-derived ROS, mitoapocynin may have therapeutic applications for reversing CPF-induced dopaminergic neurotoxicity and associated neurobehavioral deficits as well as neurodegenerative diseases.

Contrasting roles of H3K4me3 and H3K9me3 in regulation of apoptosis and gemcitabine resistance in human pancreatic cancer cells

BackgroundPancreas ductal adenocarcinoma (PDAC) has the most dismal prognosis among all human cancers since it is highly resistant to chemotherapy, radiotherapy and immunotherapy. The anticipated consequence of all therapies is induction of tumor apoptosis. The highly resistance nature of PDACs to all therapies suggests that the intrinsic tumor cell factors, likely the deregulated apoptosis pathway, are key mechanisms underlying PDAC non-response to these therapies, rather than the therapeutic agents themselves. The aim of this study is to test the hypothesis that epigenetic dysregulation of apoptosis mediators underlies PDAC resistance to gemcitabine, the standard chemotherapy for human PDAC.MethodsPDAC cells were analyzed for apoptosis sensitivity in the presence of a selective epigenetic inhibitor. The epigenetic regulation of apoptosis regulators was determined by Western Blotting and quantitative PCR. The specific epigenetic modification of apoptosis regulator promoter chromatin was determined by chromatin immunoprecipitation in PDAC cells.ResultsInhibition of histone methyltransferase (HMTase) by a selective HMTase inhibitor, verticillin A, significantly increased human PDAC cell sensitivity to gemcitabine-induced growth suppression. Verticillin A treatment decreased FLIP, Mcl-1, Bcl-x and increased Bak, Bax and Bim protein level in the tumor cells, resulting in activation of caspases, elevated cytochrome C release and increased apoptosis as determined by upregulated PARP cleavage in tumor cells. Analysis of human PDAC specimens indicated that the expression levels of anti-apoptotic mediators Bcl-x, Mcl-1, and FLIP were significantly higher, whereas the expression levels of pro-apoptotic mediators Bim, Bak and Bax were dramatically lower in human PDAC tissues as compared to normal pancreas. Verticillin A downregulated H3K4me3 levels at the BCL2L1, CFLAR and MCL-1 promoter to decrease Bcl-x, FLIP and Mcl-1 expression level, and inhibited H3K9me3 levels at the BAK1, BAX and BCL2L11 promoter to upregulate Bak, Bax and Bim expression level.ConclusionWe determined that PDAC cells use H3K4me3 to activate Bcl-x, FLIP and Mcl-1, and H3K9me3 to silence Bak, Bax and Bim to acquire an apoptosis-resistant phenotype. Therefore, selective inhibition of H3K4me3 and H3K9me3 is potentially an effective approach to overcome PDAC cells resistance to gemcitabine.

Promoter Methylation Status of Survival-Related Genes in MOLT- 4 Cells Co-Cultured with Bone Marrow Mesenchymal Stem Cells under Hypoxic Conditions.

Objective DNA methylation is a well-studied epigenetic mechanism that is a potent arm of the gene expression controlling machinery. Since the hypoxic situation and the various cells of bone marrow microenvironment, e.g. mesenchymal stem cells, play a role in the in vivo and in vitro biology of leukemic cells, we decided to study the effects of hypoxia and mesenchymal stem cells (MSCs) on the promoter methylation pattern of BAX and BCL2 genes. Materials and Methods In this experimental study, the co-culture of MOLT-4 cells with MSCs and treatment with CoCl2 was done during 6, 12, and 24 hour periods. Total DNA was extracted using commercial DNA extraction kits, and sodium bisulfite (SBS) treatment was performed on the extracted DNA. Methylation specific polymerase chain reaction (MSP) was used to evaluate the methylation status of the selected genes’ promoter regions. Results The BAX and BCL2 promoters of untreated MOLT-4 cells were in partial methylated and fully unmethylated states, respectively. After incubating the cancer cells with CoCl2and MSCs, the MSP results after 6, 12, and 24 hours were the same as untreated MOLT-4 cells. In other words, the exposure of MOLT-4 cells to the hypoxia-mimicry agent and MSCs in various modes and different time frames showed that these factors have exerted no change on the methylation signature of the studied fragments from the promoter region of the mentioned genes. ConclusionHypoxia and MSCs actually have no notable effect on the methylation status of the promoters of BAX and BCL2 in the specifically studied regions. DNA methylation is probably not the main process by which MSCs and CoCl2 induced hypoxia regulate the expression of these genes. Finally, we are still far from discovering the exact functional mechanisms of gene expression directors, but these investigations can provide new insights into this field for upcoming studies.

Chemoradiation therapy induces in vivo changes in gene promoter methylation & gene transcript expression in patients with invasive cervical cancer.

Background & objectives:Invasive cervical cancer patients are primarily treated with chemoradiation therapy. The overall and disease-free survival in these patients is variable and depends on the tumoral response apart from the tumour stage. This study was undertaken to assess whether in vivo changes in gene promoter methylation and transcript expression in invasive cervical cancer were induced by chemoradiation. Hence, paired pre- and post-treatment biopsy samples were evaluated for in vivo changes in promoter methylation and transcript expression of 10 genes (ESR1, BRCA1, RASSF1A, MYOD1, MLH1, hTERT, MGMT, DAPK1, BAX and BCL2L1) in response to chemoradiation therapy.Methods:In patients with locally advanced invasive cervical cancer, paired pre- and post-treatment biopsies after 10 Gy chemoradiation were obtained. DNA/RNA was extracted and gene promoter methylation status was evaluated by custom-synthesized methylation PCR arrays, and the corresponding gene transcript expression was determined by absolute quantification method using quantitative reverse transcription PCR.Results:Changes in the gene promoter methylation as well as gene expression following chemoradiation therapy were observed. BAX promoter methylation showed a significant increase (P< 0.01) following treatment. There was a significant increase in the gene transcript expression of BRCA1 (P< 0.01), DAPK1 and ESR1 (P< 0.05), whereas MYOD1 and MLH1 gene transcript expression was significantly decreased (P< 0.05) following treatment.Interpretation & conclusions:The findings of our study show that chemoradiation therapy can induce epigenetic alterations as well as affect gene expression in tissues of invasive cervical cancer which may have implications in determining radiation response.

A novel germline TP53 mutation p.Pro190Arg detected in a patient with lung and bilateral breast cancers

PurposeLi-Fraumeni syndrome (LFS) is a rare genetic disease with strong predispositions to multiple early-onset neoplasms, mostly sarcomas, breast cancers, brain tumors and adrenocortical carcinomas (LFS core cancers). In most LFS families the germline mutations of TP53 tumor suppressor gene were found. Lung cancer does not belong to the core cancers of LFS, however its higher incidence is observed in families with TP53 mutations. Our aim was to search for TP53 mutations in female lung cancer patients whose clinico-demographic characteristics suggested a probable genetic predisposition to the disease. Materials and methodsThe coding region of TP53 from blood DNA was sequenced using Sanger method. The functioning of detected mutation was tested by luciferase reporter assay. ResultsWe found a nucleotide substitution c.569C>G, p.Pro190Arg, which was not described in the TP53 germline mutation database (http://p53.iarc.fr/TP53GermlineMutations.aspx). The mutation destroys the ability of p53 to transactivate BAX promoter and significantly reduces transactivation potential of p53 toward the promoter of MDM2 gen. ConclusionWe identified novel germline mutation of TP53.

SIRT6 Overexpression Potentiates Apoptosis Evasion in Hepatocellular Carcinoma via BCL2-Associated X Protein–Dependent Apoptotic Pathway

To characterize the functional role of SIRT6 in hepatocellular carcinoma (HCC). The expression of SIRT6 in 60 paired paraffin-embedded HCC tissues and adjacent nontumoral liver tissues was examined by immunohistochemistry. The expression of SIRT6 in 101 paired frozen HCC tissues and adjacent nontumoral liver tissues was analyzed by Western blotting analysis and qPCR. The biologic consequences of overexpression and knockdown of SIRT6 in HCC cell lines were studied in vitro and in vivo SIRT6 expression was frequently upregulated in clinical HCC samples, and its expression was highly associated with tumor grade (P = 0.02), tumor size (P = 0.02), vascular invasion (P = 0.004), and shorter survival (P = 0.024). Depletion of SIRT6 from multiple liver cancer cell lines inhibited their growth and induced apoptosis in vitro At the molecular level, we observed that the activation of the BCL2-associated X protein (Bax) signaling pathway, a major pathway that determines cancer cell apoptosis, is regulated by SIRT6 via its deacetylase activity. SIRT6 was recruited to the promoter of Bax, where it deacetylated histone 3 lysine 9 and suppressed its promoter activity. Binding of transcription factors (p53 and E2F-1) to Bax promoter was also generally increased in SIRT6-depleted cells. In mouse xenografts, SIRT6 suppression inhibited tumor growth and induced apoptosis. Finally, there is a negative correlation between SIRT6 and Bax mRNA expressions in human HCC samples. SIRT6 is an important protumorigenic factor in liver carcinogenesis. Thus, the therapeutic targeting of SIRT6 may offer options for HCC treatment. Clin Cancer Res; 22(13); 3372-82. ©2016 AACR.

Yin Yang-1 increases apoptosis through Bax activation in pancreatic cancer cells.

The transcriptional regulator Yin Yang-1 (YY1) is a tumor suppressor known to be overexpressed in pancreatic cancer. We found that overexpression of YY1 promoted apoptosis and increased the expression and mitochondrial localization of the pro-apoptotic Bax protein in pancreatic cancer cell lines. Luciferase reporter, electrophoretic mobility shift (EMSA), and chromatin immunoprecipitation (ChIP) assays revealed binding of YY1 to the BAX promoter. Moreover, YY1 promoted pancreatic cancer cell apoptosis through Bax transcriptional activation and subsequent translocation of Bax to the mitochondrial membrane, leading to cytochrome c release, and caspase activation.YY1 and BAX are co-expressed in pancreatic cancer tissues and higher BAX expression predicts better outcomes for patients. The ability of YY1 to promote apoptosis in pancreatic cancer cells suggests it may represent a valuable diagnostic and therapeutic target.

Gambogic Acid Inhibits Malignant Melanoma Cell Proliferation Through Mitochondrial p66shc/ROS-p53/Bax-Mediated Apoptosis

Background/Aims: Malignant melanoma has high metastatic potential, is highly resistant to chemotherapy, and has a poor survival rate. Gambogic acid (GA), a polyprenylated xanthone extracted from a traditional Chinese medicinal herb, has been proven to exhibit antitumor activity. The present study aimed to investigate the signaling pathways that mediated GA-induced inhibition of human malignant skin melanoma proliferation. Methods: The study was conducted using A375 cells and the corresponding tumor transplanted in nude mice. Results: Incubation of A375 cells with 1-10 μg/ml GA decreased cell viability and increased apoptosis. GA concentration-dependently increased p66^shc expression and intracellular ROS levels. GA also decreased the oxygen consumption rate and the mitochondrial membrane potential (MMP) in A375 cells. Experimental inhibition of p66^shc by siRNA suppressed GA-induced increase of ROS, decrease of oxygen consumption rate, MMP and cell viability, whilst suppressing GA-induced increase of apoptosis. GA concentration-dependently upregulated p53 and Bax expression in A375 cells. GA also increased p53-TA-luciferase activity and p53-binding to Bax promoter, which was inhibited by Sip53. Experimental inhibition of p53 with Sip53 blocked GA-induced decrease of the oxygen consumption rate and cell viability, and blocked the increase of apoptosis. In tumor-bearing nude mice, GA notably inhibited tumor growth, and this action was suppressed by N-acetylcysteine (NAC), a potent antioxidant, and by PFT-α, a p53 inhibitor. In A375 tumors transplanted in nude mice, GA increased both p66^shc and p53 expression. NAC and PFT-α treatment did not significantly affect p66^shc expression in tumors grown in mice treated with GA. In contrast, both NAC and PFT-α treatment inhibited GA-induced p53 expression in mouse tumors. Conclusion: Results provided novel preclinical insights into the chemotherapeutic use of GA by highlighting the importance of p66^shc/ROS-p53/Bax pathways in the antitumor effect of GA in malignant melanoma.