DNA damage sensor γ -H2AX is increased in preneoplastic lesions of hepatocellular carcinoma

New Insights into How Melatonin Ameliorates Bisphenol A-Induced Colon Damage: Inhibition of NADPH Oxidase

Bisphenol A (BPA) is an endocrine disruptor, widely employed, and detected in many consumer products and food items. Oral intake poses a great threat to intestinal health. Melatonin (MT) stands out as an endogenous, dietary, and therapeutic molecule with potent antioxidant capacity. To explore the protective effect of MT against BPA-induced colon damage and the role of NADPH oxidase (NOX) in this process, we established mice and colonic epithelial cell (NCM460) models of BPA exposure and treated with MT. In vitro and in vivo results showed that MT ameliorated BPA-induced oxidative stress, DNA damage, and the G2/M cell cycle arrest. MT also downregulated the expression of NOX family-related genes, reversed the inhibition of the base excision repair (BER) pathway, promoted the activation of non-homologous end-joining (NHEJ) pathway, and suppressed the mRNA and protein expression of ATM, Chk1/2, and p53. Diphenyleneiodonium chloride (DPI), a NOX-specific inhibitor, also attenuated the toxic effects of BPA on NCM460 cells. Furthermore, molecular docking revealed that MT could bind to NOX. Conclusively, our finding suggested that MT can ameliorate BPA-induced colonic DNA damage by scavenging NOX-derived ROS, which further attenuates G2/M cell cycle arrest dependent on the ATM-Chk1/2-p53 axis.

A necroptosis -related signature for predicting prognosis and immunotherapy in hepatocellular carcinoma

Background: Hepatocellular Carcinoma (HCC) is an aggressive tumor with an inferior prognosis. Necroptosis is a new form of programmed death that plays a dual effect on the tumor. However, the role of necroptosis-related genes(NRGs) in HCC remains unknown.

Methods: All datasets were downloaded from publicly available databases. The consensus clustering analysis was used to classify patients into different subtypes based on NRGs. The Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression were used to develop a prognostic signature. Tumor Immune Dysfunction and Exclusion (TIDE) was used to predict immunotherapy response.

Results: The genetic and transcriptional changes of NRGs were observed in HCC. Patients were classified into three clusters based on differentially expressed NRGs, of which Cluster-3 had the worst prognosis and the highest immune infiltration. The prognostic signature was developed based on 8-NRGs, which have shown excellent prognostic performance. The high-risk group in the signature presented significantly higher immune infiltration, such as aDCs, iDCs, macrophages, and Treg, compared to the low-risk group. TMB and immune checkpoints were also higher in the high-risk group. Moreover, a lower TIDE score was observed in the high-risk group, indicating the patients with high risk-score may be suitable for immunotherapy. Via the dataset of IMvigor210, we found a higher risk score in the immunotherapy response group.

Conclusion: We developed a new necroptosis-related signature for predicting prognosis with the potential to predict immunotherapy for HCC patients.

Tumor Promoting Effects of Sulforaphane on Diethylnitrosamine-Induced Murine Hepatocarcinogenesis

Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor involved in protection against initiation of carcinogenesis in normal cells. Notably, recent studies have demonstrated that aberrant activation of NRF2 accelerates the proliferation and progression of cancer cells. The differential effects of NRF2 on multi-stage carcinogenesis have raised a concern about the validity of NRF2 activators for chemoprevention. This prompted us to assess the effects of sulforaphane (SFN), a prototypic NRF2 activating chemopreventive phytochemical, on experimentally induced carcinogenesis. In the present study, SFN was daily injected intraperitoneally (25 mg/kg) for 3 months to male C57BL/6 mice at 6 months after single intraperitoneal administration of a hepatocarcinogen, diethylnitrosamine (DEN). The liver to body weight ratio, tumor growth, and the number and the size of hepatomas measured at 9 months after DEN administration were significantly higher in SFN-treated mice than those in vehicle-treated mice. Moreover, the expression of NRF2, its target protein NAD(P)H:quinone oxidoreductase 1, and the cell proliferation marker, proliferating cell nuclear antigen was further elevated in DEN plus SFN-treated mice. These results suggest that once hepatocarcinogenesis is initiated, SFN may stimulate tumor progression.

Epigenetic remodelling in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer, being the sixth most commonly diagnosed cancer and the fourth leading cause of cancer-related death. As other heterogeneous solid tumours, HCC results from a unique synergistic combination of genetic alterations mixed with epigenetic modifications.In HCC the patterns and frequencies of somatic variations change depending on the nearby chromatin. On the other hand, epigenetic alterations often induce genomic instability prone to mutations. Epigenetics refers to heritable states of gene expression without alteration to the DNA sequence itself and, unlike genetic changes, the epigenetic modifications are reversible and affect gene expression more extensively than genetic changes. Thus, studies of epigenetic regulation and the involved molecular machinery are greatly contributing to the understanding of the mechanisms that underline HCC onset and heterogeneity. Moreover, this knowledge may help to identify biomarkers for HCC diagnosis and prognosis, as well as future new targets for more efficacious therapeutic approaches.In this comprehensive review we will discuss the state-of-the-art knowledge about the epigenetic landscape in hepatocarcinogenesis, including evidence on the diagnostic and prognostic role of non-coding RNAs, modifications occurring at the chromatin level, and their role in the era of precision medicine.Apart from other better-known risk factors that predispose to the development of HCC, characterization of the epigenetic remodelling that occurs during hepatocarcinogenesis could open the way to the identification of personalized biomarkers. It may also enable a more accurate diagnosis and stratification of patients, and the discovery of new targets for more efficient therapeutic approaches.

Acox2 is a regulator of lysine crotonylation that mediates hepatic metabolic homeostasis in mice

Acyl-CoA oxidase 2 (Acox2) is an enzyme involved in peroxisomal bile acid synthesis and branched-chain fatty acid degradation. Acox2 knockout (−/−) mice spontaneously developed liver cancer with marked lymphocytic infiltrate. Tandem-affinity purification coupled with mass spectrometry analysis revealed that Acox2 interacted with methylcrotonoyl-CoA carboxylase followed by co-immunoprecipitation confirmation. Here we reported that non-histone lysine crotonylation (Kcr) levels were downregulated in Acox2^−/− mice livers. Interestingly, Kcr signals were concentrated in the nucleus of tumor cells but mostly located in the cytoplasm of adjacent normal liver cells of Acox2^−/− mice. Quantitative analysis of the global crotonylome further revealed that 54% (27/50) of downregulated non-histone Kcr sites were located in mitochondrial (11/50) and peroxisomal (17/50) enzymes including Ehhadh, Scp2, Hsd17b4, Crot, Etfa, Cpt1a, Eci1/2, Hadha, Etfdh, and Idh2. Subsequent site-directed mutagenesis and transcriptome analysis revealed that Ehhadh K⁵⁷²cr might have site-specific regulatory roles by downregulating TOP3B expression that lead to increased DNA damage in vitro. Our findings suggested Acox2 is a regulator of Kcr that might play critical role on hepatic metabolic homeostasis.

Metronidazole enhances steatosis-related early-stage hepatocarcinogenesis in high fat diet-fed rats through DNA double-strand breaks and modulation of autophagy

Nonalcoholic fatty liver disease is a hepatic disorder with deposition of fat droplets and has a high risk of progression to steatosis-related hepatitis and irreversible hepatic cancer. Metronidazole (MNZ) is an antiprotozoal and antimicrobial agent widely used to treat patients infected with anaerobic bacteria and intestinal parasites; however, MNZ has also been shown to induce liver tumors in rodents. To investigate the effects of MNZ on steatosis-related early-stage hepatocarcinogenesis, male rats treated with N-nitrosodiethylamine following 2/3 hepatectomy at week 3 were received a control basal diet, high fat diet (HFD), or HFD containing 0.5% MNZ. The HFD induced obesity and steatosis in the liver, accompanied by altered expression of Pparg and Fasn, genes related to lipid metabolism. MNZ increased nuclear translocation of lipid metabolism-related transcription factor peroxisome proliferator-activated receptor gamma in hepatocytes, together with altered liver expression of lipid metabolism genes (Srebf1, Srebf2, Pnpla2). Furthermore, MNZ significantly increased the number of preneoplastic liver foci, accompanied by DNA double-strand breaks and late-stage autophagy inhibition, as reflected by increased levels of γ-H2AX, LC3, and p62. Therefore, MNZ could induce steatosis-related hepatocarcinogenesis by inducing DNA double-strand breaks and modulating autophagy in HFD-fed rats.

HIST3H2A is a potential biomarker for pancreatic cancer: A study based on TCGA data

ABSTRACT

The family of histone H2A proved that there are a lot of variants associated with cancer development. The link between HIST3H2A and pancreatic cancer has never been noted before. Our research suggests that HIST3H2A affects pancreatic tumor immune process and prognosis of patients, through the JAK STAT pathway, so it is expected to become the biomarker of pancreatic cancer.Gene expression profiles and clinical data of pancreatic cancer patients were downloaded from The Cancer Genome Atlas database (TCGA) and The Genotype Tissue Expression (GETx) project. R software (Rx64 3.6.0) was utilized to analyze. Gene set enrichment analysis (GSEA) was used to analyze HIST3H2A related signaling pathways in pancreatic cancer. CIBERSORT is applied to estimate the compositional patterns of the 22 types of immune cell fraction based on bulk expression data.HIST3H2A was expressed at higher in pancreatic cancer tissues than normal pancreatic tissues. Kaplan-Meier survival analysis suggested that the level of HIST3H2A expression affect prognosis of pancreatic cancer patients. Univariate Cox analysis and Multivariate Cox analysis suggested that HIST3H2A expression is a prognostic factor of pancreatic cancer. Cor expression analysis indicated that the genes positively correlated with HIST3H2A expression trend were DCST1-AS1, HIST1H2BD, SLC12A9-AS1. GSEA showed that the JAK-STAT signaling pathway was enriched in the HIST3H2A high expression phenotype, whereas intestinal network for IgA production, Asthma and Chemokine signaling pathway were enriched in the HIST3H2A low expression phenotype. In additional, results showed that CD8 T cells (P = .007), activated CD4 memory T cells (P = .001), and monocytes (P = .002) were more abundant in lower HIST3H2A expression groups.HIST3H2A is a promising biomarker for predicting prognosis of pancreatic cancer, and it could be a potential therapeutic target. HIST3H2A might regulate the progression of tumor immune in pancreatic cancer through modulating the JAK-STAT pathway. In addition, the role HIST3H2A in pancreatic cancer may be related to DCST1-AS1, HIST1H2B, SLC12A9-AS1. However, more research is necessary to validate findings.

Identification of Gene Signature as Diagnostic and Prognostic Blood Biomarker for Early Hepatocellular Carcinoma Using Integrated Cross-Species Transcriptomic and Network Analyses

Background: Hepatocellular carcinoma (HCC) is considered the most common type of liver cancer and the fourth leading cause of cancer-related deaths in the world. Since the disease is usually diagnosed at advanced stages, it has poor prognosis. Therefore, reliable biomarkers are urgently needed for early diagnosis and prognostic assessment. Methods: We used genome-wide gene expression profiling datasets from human and rat early HCC (eHCC) samples to perform integrated genomic and network-based analyses, and discovered gene markers that are expressed in blood and conserved in both species. We then used independent gene expression profiling datasets for peripheral blood mononuclear cells (PBMCs) for eHCC patients and from The Cancer Genome Atlas (TCGA) database to estimate the diagnostic and prognostic performance of the identified gene signature. Furthermore, we performed functional enrichment, interaction networks and pathway analyses. Results: We identified 41 significant genes that are expressed in blood and conserved across species in eHCC. We used comprehensive clinical data from over 600 patients with HCC to verify the diagnostic and prognostic value of 41-gene-signature. We developed a prognostic model and a risk score using the 41-geneset that showed that a high prognostic index is linked to a worse disease outcome. Furthermore, our 41-gene signature predicted disease outcome independently of other clinical factors in multivariate regression analysis. Our data reveals a number of cancer-related pathways and hub genes, including EIF4E, H2AFX, CREB1, GSK3B, TGFBR1, and CCNA2, that may be essential for eHCC progression and confirm our gene signature's ability to detect the disease in its early stages in patients' biological fluids instead of invasive procedures and its prognostic potential. Conclusion: Our findings indicate that integrated cross-species genomic and network analysis may provide reliable markers that are associated with eHCC that may lead to better diagnosis, prognosis, and treatment options.

Impact of DNA double-strand breaks on pancreaticobiliary maljunction carcinogenesis

BACKGROUND

Pancreaticobiliary maljunction (PBM) is a condition characterized by chronic inflammation due to refluxed pancreatic juice into the biliary tract that is associated with an elevated risk of biliary tract cancer. DNA double-strand breaks (DSBs) are considered the most serious form of DNA damage. DSBs are provoked by inflammatory cell damage and are recognized as an important oncogenic event in several cancers. This study used γ-H2AX, an established marker of DSB formation, to evaluate the impact of DNA damage on carcinogenesis in PBM.

METHODS

We investigated γ-H2AX expression immunohistochemically in gallbladder epithelium samples obtained from 71 PBM cases and 19 control cases.

RESULTS

Fourteen PBM cases with gallbladder adenocarcinoma were evaluated at non-neoplastic regions. A wide range of nuclear γ-H2AX staining was detected in all PBM and control specimens. γ-H2AX expression was significantly higher in PBM cases versus controls (median γ-H2AX-positive proportion: 14.4 % vs. 4.4 %, p = 0.001). Among the PBM cases, γ-H2AX expression was significantly higher in patients with carcinoma than in those without (median γ-H2AX-positive proportion: 21.4 % vs. 11.0 %, p = 0.031).

CONCLUSIONS

DSBs occurred significantly more abundantly in the PBM gallbladder mucosa, especially in the context of cancer, indicating an involvement in PBM-related carcinogenesis.

CDCA8, targeted by MYBL2, promotes malignant progression and olaparib insensitivity in ovarian cancer

Ovarian cancer is the most lethal gynecologic malignancy. Poly (ADP-ribose) polymerase inhibitors (PARPi) are effective in treating ovarian cancer. However, cancer cell insensitivity and resistance remain challenges. Determination of the exact chemoresistance mechanisms and potential targeted therapies is urgent. CDCA8 (cell division cycle associated 8) participates in the tumorigenesis of various cancers; however, the exact biological function of CDCA8 in ovarian cancer remains obscure. Here, we found that CDCA8 was overexpressed in ovarian cancer and that high expression of CDCA8 promoted the proliferation of ovarian cancer cells in vitro and in vivo. Moreover, silencing of CDCA8 sensitized ovarian cancer cells to olaparib and cisplatin by inducing G2/M arrest, accelerating apoptosis, increasing DNA damage and interfering with RAD51 accumulation in vitro. In addition, MYBL2 (MYB proto-oncogene-like 2), identified as an upstream transcription factor of CDCA8, was positively correlated with the expression level of CDCA8 in ovarian cancer. Finally, MYBL2 enhanced the aggressive characteristics of ovarian cancer cells by regulating CDCA8. In conclusion, high CDCA8 expression was involved in the tumorigenesis, aggressiveness and chemoresistance of ovarian cancer. CDCA8 silencing combined with olaparib treatment might lead to substantial progress in ovarian cancer targeted therapy.

Rational combination therapy for hepatocellular carcinoma with PARP1 and DNA-PK inhibitors

Understanding differences in DNA double-strand break (DSB) repair between tumor and normal tissues would provide a rationale for developing DNA repair-targeted cancer therapy. Here, using knock-in mouse models for measuring the efficiency of two DSB repair pathways, homologous recombination (HR) and nonhomologous end-joining (NHEJ), we demonstrated that both pathways are up-regulated in hepatocellular carcinoma (HCC) compared with adjacent normal tissues due to altered expression of DNA repair factors, including PARP1 and DNA-PKcs. Surprisingly, inhibiting PARP1 with olaparib abrogated HR repair in HCC. Mechanistically, inhibiting PARP1 suppressed the clearance of nucleosomes at DNA damage sites by blocking the recruitment of ALC1 to DSB sites, thereby inhibiting RPA2 and RAD51 recruitment. Importantly, combining olaparib with NU7441, a DNA-PKcs inhibitor that blocks NHEJ in HCC, synergistically suppressed HCC growth in both mice and HCC patient-derived-xenograft models. Our results suggest the combined inhibition of both HR and NHEJ as a potential therapy for HCC.

Time-dependent changes in proliferation, DNA damage and clock gene expression in hepatocellular carcinoma and healthy liver of a transgenic mouse model

Hepatocellular carcinoma (HCC) is highly resistant to anticancer therapy and novel therapeutic strategies are needed. Chronotherapy may become a promising approach because it may improve the efficacy of antimitotic radiation and chemotherapy by considering timing of treatment. To date little is known about time-of-day dependent changes of proliferation and DNA damage in HCC. Using transgenic c-myc/transforming growth factor (TGFα) mice as HCC animal model, we immunohistochemically demonstrated Ki67 as marker for proliferation and γ-H2AX as marker for DNA damage in HCC and surrounding healthy liver (HL). Core clock genes (Per1, Per2, Cry1, Cry2, Bmal 1, Rev-erbα and Clock) were examined by qPCR. Data were obtained from samples collected ex vivo at four different time points and from organotypic slice cultures (OSC). Significant differences were found between HCC and HL. In HCC, the number of Ki67 immunoreactive cells showed two peaks (ex vivo: ZT06 middle of day and ZT18 middle of night; OSC: CT04 and CT16). In ex vivo samples, the number of γ-H2AX positive cells in HCC peaked at ZT18 (middle of the night), while in OSC their number remained high during subjective day and night. In both HCC and HL, clock gene expression showed a time-of-day dependent expression ex vivo but no changes in OSC. The expression of Per2 and Cry1 was significantly lower in HCC than in HL. Our data support the concept of chronotherapy of HCC. OSC may become useful to test novel cancer therapies.

KRas-ERK signalling promotes the onset and maintenance of uveal melanoma through regulating JMJD6-mediated H2A.X phosphorylation at tyrosine 39

Since DNA damage is a first incident occurred during a tumour attack, it is rational that histone H2A.X phosphorylation on tyrosine 39 (H2A.X^Y39ph) may act as a tumour-relevant factor. This study was aimed to test the authenticity of the hypothesis. Uveal melanoma MP65 cells were transfected for expression of KRas mutated. H2A.X phosphorylation and ERK1/2 was measured, and transwell experiment was performed to examine the consequents of H2A.X^Y39ph on MP65 cells developing and migration. Regulatory relationship between H2A.X^Y39ph and ERK1/2 downstream genes were measured. Moreover, whether JMJD6 and MDM2 are involved in H2A.X phosphorylation was studied. Mutation of Ras activated ERK1/2 signalling and inhibited H2A.X phosphorylation at Y39. Silence of H2A.X^Y39ph contributed to the regulation of MP65 cells growth, migration and transcription of ERK1/2 downstream genes, including CYR61, IGFBP3, WNT16B, NT5E, GDF15 and CARD16. The repressed H2A.X phosphorylation through Ras-ERK1/2 signalling might be through MDM2-mediated JMJD6 degradation. Our study suggested that Ras-ERK1/2 signalling inhibited H2A.X phosphorylation at Y39, which led to the uncontrolled developing and migration of uveal melanoma cells. In addition, H2A.X phosphorylation was mediated possibly through JMJD6 which could be degraded by MDM2.

Diethylnitrosamine and thioacetamide-induced hepatic damage and early carcinogenesis in rats: Role of Nrf2 activator dimethyl fumarate and NLRP3 inhibitor glibenclamide

Two-stage rat hepatocarcinogenesis model was used to induce early carcinogenesis in which thioacetamide (TAA) promotes diethylnitrosamine (DEN) initiated carcinogenesis. Dimethyl fumarate (DMF) used to treat multiple sclerosis, activates the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant responsive element (ARE) pathway during oxidative stress, and maintains antioxidant levels. Glibenclamide (GLB), a sulphonylurea drug used to treat type II diabetes, possesses anti-inflammatory properties and inhibits NLRP3 inflammasomes. The present study was designed to investigate the concurrent intervention of DMF and GLB on DEN + TAA-induced early hepatic carcinogenesis. DMF and GLB treatment improved DEN + TAA-induced decrease in body weight, increase in liver weight and plasma transaminases, histopathological alterations, DNA damage, and apoptosis. DMF and GLB intervention significantly ameliorated the DEN + TAA-induced alterations in the antioxidant (Nrf2, HO-1, SOD-1, catalase), inflammatory (NF-κB, NLRP3, ASC, caspase-1), fibrogenic (TGF-β1, collagen) and regenerative proliferative stress (GST-p, HGF, c-MET, TGFα, EGF, AFP) markers. The present results indicate that Nrf2/ARE activation and NLRP3 inhibition might be a rational approach to attenuate oxidative stress and chronic inflammation associated progression of hepatocarcinogenesis.

Replenishment of Hepatitis B Virus cccDNA Pool Is Restricted by Baseline Expression of Host Restriction Factors In Vitro

BACKGROUND

Covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is the major cause of viral persistence in patients with chronic HBV infection. Understanding the mechanisms underlying stability and persistence of HBV cccDNA in hepatocytes is critical for developing novel therapeutics and managing chronic hepatitis B. In this study, we observed an unexpected increase in HBV cccDNA levels upon suppression of transcription by de novo DNA methyltransferase DNMT3A and uncovered additional mechanisms potentially involved in HBV cccDNA maintenance.

METHODS

HBV-expressing cell lines were transfected with a DNMT3A-expressing plasmid. Real-time PCR and HBsAg assays were used to assess the HBV replication rate. Cell cycling was analyzed by fluorescent cell sorting. CRISPR/Cas9 was utilized to abrogate expression of APOBEC3A and APOBEC3B. Alterations in the expression of target genes were measured by real-time PCR.

RESULTS

Similar to previous studies, HBV replication induced DNMT3A expression, which in turn, led to reduced HBV transcription but elevated HBV cccDNA levels (4- to 6-fold increase). Increased levels of HBV cccDNA were not related to cell cycling, as DNMT3A accelerated proliferation of infected cells and could not contribute to HBV cccDNA expansion by arresting cells in a quiescent state. At the same time, DNMT3A suppressed transcription of innate immunity factors including cytidine deaminases APOBEC3A and APOBEC3B. CRISPR/Cas9-mediated silencing of APOBEC3A and APOBEC3B transcription had minor effects on HBV transcription, but significantly increased HBV cccDNA levels, similar to DNMT3A. In an attempt to further analyze the detrimental effects of HBV and DNMT3A on infected cells, we visualized γ-H2AX foci and demonstrated that HBV inflicts and DNMT3A aggravates DNA damage, possibly by downregulating DNA damage response factors. Additionally, suppression of HBV replication by DNMT3A may be related to reduced ATM/ATR expression.

CONCLUSION

Formation and maintenance of HBV cccDNA pools may be partially suppressed by the baseline expression of host inhibitory factors including APOBEC3A and APOBEC3B. HBV inflicts DNA damage both directly and by inducing DNMT3A expression.

ATM and ATR Expression Potentiates HBV Replication and Contributes to Reactivation of HBV Infection upon DNA Damage

Chronic hepatitis B virus infection (CHB) caused by the hepatitis B virus (HBV) is one of the most common viral infections in the world. Reactivation of HBV infection is a life-threatening condition observed in patients with CHB receiving chemotherapy or other medications. Although HBV reactivation is commonly attributed to immune suppression, other factors have long been suspected to play a role, including intracellular signaling activated in response to DNA damage. We investigated the effects of DNA-damaging factors (doxorubicin and hydrogen peroxide) on HBV reactivation/replication and the consequent DNA-damage response. Dose-dependent activation of HBV replication was observed in response to doxorubicin and hydrogen peroxide which was associated with a marked elevation in the mRNA levels of ataxia-telangiectasia mutated (ATM) and ATM- and RAD3-related (ATR) kinases. Downregulation of ATM or ATR expression by shRNAs substantially reduced the levels of HBV RNAs and DNA. In contrast, transcriptional activation of ATM or ATR using CRISPRa significantly increased HBV replication. We conclude that ATM and ATR are essential for HBV replication. Furthermore, DNA damage leading to the activation of ATM and ATR transcription, results in the reactivation of HBV replication.

Splicing events in the control of genome integrity: role of SLU7 and truncated SRSF3 proteins

Genome instability is related to disease development and carcinogenesis. DNA lesions are caused by genotoxic compounds but also by the dysregulation of fundamental processes like transcription, DNA replication and mitosis. Recent evidence indicates that impaired expression of RNA-binding proteins results in mitotic aberrations and the formation of transcription-associated RNA-DNA hybrids (R-loops), events strongly associated with DNA injury. We identify the splicing regulator SLU7 as a key mediator of genome stability. SLU7 knockdown results in R-loops formation, DNA damage, cell-cycle arrest and severe mitotic derangements with loss of sister chromatid cohesion (SCC). We define a molecular pathway through which SLU7 keeps in check the generation of truncated forms of the splicing factor SRSF3 (SRp20) (SRSF3-TR). Behaving as dominant negative, or by gain-of-function, SRSF3-TR impair the correct splicing and expression of the splicing regulator SRSF1 (ASF/SF2) and the crucial SCC protein sororin. This unique function of SLU7 was found in cancer cells of different tissue origin and also in the normal mouse liver, demonstrating a conserved and fundamental role of SLU7 in the preservation of genome integrity. Therefore, the dowregulation of SLU7 and the alterations of this pathway that we observe in the cirrhotic liver could be involved in the process of hepatocarcinogenesis.

Orthologous CRISPR/Cas9 systems for specific and efficient degradation of covalently closed circular DNA of hepatitis B virus

Covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is the major cause of viral persistence and chronic hepatitis B. CRISPR/Cas9 nucleases can specifically target HBV cccDNA for decay, but off-target effects of nucleases in the human genome limit their clinical utility. CRISPR/Cas9 systems from four different species were co-expressed in cell lines with guide RNAs targeting conserved regions of the HBV genome. CRISPR/Cas9 systems from Streptococcus pyogenes (Sp) and Streptococcus thermophilus (St) targeting conserved regions of the HBV genome blocked HBV replication and, most importantly, resulted in degradation of over 90% of HBV cccDNA by 6 days post-transfection. Degradation of HBV cccDNA was impaired by inhibition of non-homologous end-joining pathway and resulted in an erroneous repair of HBV cccDNA. HBV cccDNA methylation also affected antiviral activity of CRISPR/Cas9. Single-nucleotide HBV genetic variants did not impact anti-HBV activity of St CRISPR/Cas9, suggesting its utility in targeting many HBV variants. However, two or more mismatches impaired or blocked CRISPR/Cas9 activity, indicating that host DNA will not likely be targeted. Deep sequencing revealed that Sp CRISPR/Cas9 induced off-target mutagenesis, whereas St CRISPR/Cas9 had no effect on the host genome. St CRISPR/Cas9 system represents the safest system with high anti-HBV activity.

Splicing alterations contributing to cancer hallmarks in the liver: central role of dedifferentiation and genome instability

Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide. HCCs are molecularly heterogeneous tumors, and this complexity is to a great extent responsible for their poor response to conventional and targeted therapies. In this review we summarize recent evidence indicating that imbalanced expression of mRNA splicing factors can be a relevant source for this heterogeneity. We also discuss how these alterations may play a driver role in hepatocarcinogenesis by impinging on the general hallmarks of cancer. Considering the natural history of HCC, we focused on two pathogenic features that are characteristic of liver tumors: chromosomal instability and phenotypic de-differentiation. We highlight mechanisms connecting splicing derangement with these two processes and the enabling capacities acquired by liver cells along their neoplastic transformation. A thorough understanding of the alterations in the splicing machinery may also help to identify new HCC biomarkers and to design novel therapeutic strategies.

Clinical Implications of Hepatitis B Virus RNA and Covalently Closed Circular DNA in Monitoring Patients with Chronic Hepatitis B Today with a Gaze into the Future: The Field Is Unprepared for a Sterilizing Cure

. Chronic hepatitis B virus (HBV) infection has long remained a critical global health issue. Covalently closed circular DNA (cccDNA) is a persistent form of the HBV genome that maintains HBV chronicity. Decades of extensive research resulted in the two therapeutic options currently available: nucleot(s)ide analogs and interferon (IFN) therapy. A plethora of reliable markers to monitor HBV patients has been established, including the recently discovered encapsidated pregenomic RNA in serum, which can be used to determine treatment end-points and to predict the susceptibility of patients to IFN. Additionally, HBV RNA splice variants and cccDNA and its epigenetic modifications are associated with the clinical course and risks of hepatocellular carcinoma (HCC) and liver fibrosis. However, new antivirals, including CRISPR/Cas9, APOBEC-mediated degradation of cccDNA, and T-cell therapies aim at completely eliminating HBV, and it is clear that the diagnostic arsenal for defining the long-awaited sterilizing cure is missing. In this review, we discuss the currently available tools for detecting and measuring HBV RNAs and cccDNA, as well as the state-of-the-art in clinical implications of these markers, and debate needs and goals within the context of the sterilizing cure that is soon to come.

INCREASED FORMATION OF PHOSPHORYLATED H2AX FOCI IN NUCLEI OF CELLS INFECTED BY HEPATITIS B AND B+D VIRUSES

Liver cirrhosis and hepatocellular carcinoma are the most common outcomes of chronic hepatitis B. Hepatitis B virus (HBV) induces transformation and cell death in chronic hepatitis B (CHB). DNA double strand breaks (DSBs) represent the most dangerous type of genome damage. It was shown previously that generation of phosphorylated histone H2AX foci is a reliable marker of DSBs. The aim of this study was to analyse generation of yH2AX foci in HBV and hepatitis D virus (HDV) infection in vitro and in liver biopsies of patients with CHB and CHB with delta-agent (CHD). Human hepatoma cell line HepG2-1.1merHBV with activated HBV life cycle was used to perform real-time PCR for analysis of pregenomic RNA, HBV DNA, HBV cccDNA and for immunocytochemical analysis of yH2AX. Liver biopsies from CHB and CHD patients were analyzed to confirm the results. HBV induces multiple discrete yH2AX foci in HepG2-1.1merHBV cells in vitro and in biopsies of CHB and CHB+D patients. The ratio of hepatocytes w/o yH2AX foci is significantly lower (49,9+/-12,3% vs. 85,5+/-0,9%, p.

Post-Translational Modifications of H2A Histone Variants and Their Role in Cancer

Histone variants are chromatin components that replace replication-coupled histones in a fraction of nucleosomes and confer particular characteristics to chromatin. H2A variants represent the most numerous and diverse group among histone protein families. In the nucleosomal structure, H2A-H2B dimers can be removed and exchanged more easily than the stable H3-H4 core. The unstructured N-terminal histone tails of all histones, but also the C-terminal tails of H2A histones protrude out of the compact structure of the nucleosome core. These accessible tails are the preferential target sites for a large number of post-translational modifications (PTMs). While some PTMs are shared between replication-coupled H2A and H2A variants, many modifications are limited to a specific histone variant. The present review focuses on the H2A variants H2A.Z, H2A.X, and macroH2A, and summarizes their functions in chromatin and how these are linked to cancer development and progression. H2A.Z primarily acts as an oncogene and macroH2A and H2A.X as tumour suppressors. We further focus on the regulation by PTMs, which helps to understand a degree of context dependency.

THE ROLE OF DNA-METHYLTRANSFERASES IN THE LIFE CYCLE OF HEPATITIS B VIRUS AND PATHOGENESIS OF CHRONIC HEPATITIS B

Chronic hepatitis B is caused by a persistent form of hepatitis B virus, covalently closed circular DNA (cccDNA). Stability of cccDNA is associated with intracellular localization of cccDNA and formation of minichromosome, regulated by epigenetic mechanisms. One of the key mechanisms in epigenetics is methylation of DNA on CpG islands. Expression levels of DNA-methyltransferases (DNMTs) in chronic hepatitis B patients were shown to be upregulated. Nevertheless, the role of DNMTs in the life cycle of HBV and their effects on the cell remain elusive. In this review, we discuss latest achievements on the role of DNMTs in chronic hepatitis B and HBV in vitro models.

Liver damage and senescence increases in patients developing hepatocellular carcinoma

BACKGROUND AND AIM

Most patients with a hepatocellular carcinoma (HCC) have an underlying chronic liver inflammation, which causes a continuous damage leading to liver cirrhosis and eventually HCC. However, only a minority of cirrhotic patients develop HCC. To assess a possible differential impact of liver inflammation in patients developing HCC versus patients remaining tumor-free, we designed a longitudinal study and analysed liver tissue of the same patients (n = 33) at two points in time: once when no HCC was present and once several years later when an HCC was present. As a control group, we followed cirrhotic patients (n = 37) remaining tumor-free over a similar time frame.

METHODS

We analysed cell damage and senescence of hepatocytes by measuring γ-H2AX positivity, p16^INK4 and p21^WAF/Cip1 expression, nuclear size, and telomere length.

RESULTS

γ-H2AX positivity, p16^INK4 and p21^WAF/Cip1 expression, in the first liver biopsy was similar in patients developing HCC later on and cirrhotic patients remaining tumor free. In contrast, γ-H2AX positivity, p16^INK4 and p21^WAF/Cip1 expression, was significantly higher in the second non-tumoral liver biopsy of HCC patients than in the control patients. Consequently, the individual increase in γ-H2AX positivity, p16^INK4 and p21^WAF/Cip1 expression, from the first biopsy to the second biopsy was significantly higher in patients developing HCC than in patients remaining tumor free. In addition, changes in nuclear size and telomere length revealed a more pronounced cell aging in patients developing HCC than in patients remaining tumor free.

CONCLUSIONS

Hepatocytes from patients developing HCC go through more pronounced cell damage and senescence in contrast to cirrhotic patients remaining tumor free.

Imaging the DNA damage response with PET and SPECT

DNA integrity is constantly challenged by endogenous and exogenous factors that can alter the DNA sequence, leading to mutagenesis, aberrant transcriptional activity, and cytotoxicity. Left unrepaired, damaged DNA can ultimately lead to the development of cancer. To overcome this threat, a series of complex mechanisms collectively known as the DNA damage response (DDR) are able to detect the various types of DNA damage that can occur and stimulate the appropriate repair process. Each DNA damage repair pathway leads to the recruitment, upregulation, or activation of specific proteins within the nucleus, which, in some cases, can represent attractive targets for molecular imaging. Given the well-established involvement of DDR during tumorigenesis and cancer therapy, the ability to monitor these repair processes non-invasively using nuclear imaging techniques may facilitate the earlier detection of cancer and may also assist in monitoring response to DNA damaging treatment. This review article aims to provide an overview of recent efforts to develop PET and SPECT radiotracers for imaging of DNA damage repair proteins.

gamma-H2AX: Can it be established as a classical cancer prognostic factor?

Double-strand breaks are among the first procedures taking place in cancer formation and progression as a result of endogenic and exogenic factors. The histone variant H2AX undergoes phosphorylation at serine 139 due to double-strand breaks, and the gamma-H2AX is formatted as a result of genomic instability. The detection of gamma-H2AX can potentially serve as a biomarker for transformation of normal tissue to premalignant and consequently to malignant tissues. gamma-H2AX has already been investigated in a variety of cancer types, including breast, lung, colon, cervix, and ovary cancers. The prognostic value of gamma-H2AX is indicated in certain cancer types, such as breast or endometrial cancer, but further investigation is needed to establish gamma-H2AX as a prognostic marker. This review outlines the role of gamma-H2AX in cell cycle, and its formation as a result of DNA damage. We investigate the role of gamma-H2AX formation in several cancer types and its correlation with other prognostic factors, and we try to find out whether it fulfills the requirements for its establishment as a classical cancer prognostic factor.

Advances in Hypoxia-Mediated Mechanisms in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common and the third most deadly malignant tumor worldwide. Hypoxia and related oxidative stress are heavily involved in the process of HCC development and its therapies. However, direct and accurate measurement of oxygen concentration and evaluation of hypoxic effects in HCC prove difficult. Moreover, the hypoxia-mediated mechanisms in HCC remain elusive. Here, we summarize recent major evidence of hypoxia in HCC lesions shown by measuring partial pressure of oxygen (pO₂), the clinical importance of hypoxic markers in HCC, and recent advances in hypoxia-related mechanisms and therapies in HCC. For the mechanisms, we focus mainly on the roles of oxygen-sensing proteins (i.e., hypoxia-inducible factor and neuroglobin) and hypoxia-induced signaling proteins (e.g., matrix metalloproteinases, high mobility group box 1, Beclin 1, glucose metabolism enzymes, and vascular endothelial growth factor). With respect to therapies, we discuss mainly YQ23, sorafenib, 2-methoxyestradiol, and celastrol. This review focuses primarily on the results of clinical and animal studies.

IκB kinaseα/β control biliary homeostasis and hepatocarcinogenesis in mice by phosphorylating the cell-death mediator receptor-interacting protein kinase 1

The IκB-Kinase (IKK) complex-consisting of the catalytic subunits, IKKα and IKKβ, as well as the regulatory subunit, NEMO-mediates activation of the nuclear factor κB (NF-κB) pathway, but previous studies suggested the existence of NF-κB-independent functions of IKK subunits with potential impact on liver physiology and disease. Programmed cell death is a crucial factor in the progression of liver diseases, and receptor-interacting kinases (RIPKs) exerts strategic control over multiple pathways involved in regulating novel programmed cell-death pathways and inflammation. We hypothesized that RIPKs might be unrecognized targets of the catalytic IKK-complex subunits, thereby regulating hepatocarcinogenesis and cholestasis. In this present study, mice with specific genetic inhibition of catalytic IKK activity in liver parenchymal cells (LPCs; IKKα/β(LPC-KO) ) were intercrossed with RIPK1(LPC-KO) or RIPK3(-/-) mice to examine whether RIPK1 or RIPK3 might be downstream targets of IKKs. Moreover, we performed in vivo phospho-proteome analyses and in vitro kinase assays, mass spectrometry, and mutagenesis experiments. These analyses revealed that IKKα and IKKβ-in addition to their known function in NF-κB activation-directly phosphorylate RIPK1 at distinct regions of the protein, thereby regulating cell viability. Loss of this IKKα/β-dependent RIPK1 phosphorylation in LPCs inhibits compensatory proliferation of hepatocytes and intrahepatic biliary cells, thus impeding HCC development, but promoting biliary cell paucity and lethal cholestasis.

CONCLUSIONS

IKK-complex subunits transmit a previously unrecognized signal through RIPK1, which is fundamental for the long-term consequences of chronic hepatic inflammation and might have potential implications for future pharmacological strategies against cholestatic liver disease and cancer. (Hepatology 2016;64:1217-1231).

Overexpression of CDT1 Is a Predictor of Poor Survival in Patients with Hepatocellular Carcinoma

BACKGROUND

Genomic instability is a common feature in hepatocellular carcinoma. Deregulation of replication licensing factors has been shown to trigger DNA damage response contributing to genomic instability. Overexpression of DNA replication licensing factors chromatin licensing and DNA replication factor 1 (CDT1) and minichromosome maintenance complex component 7 (MCM7) has been previously reported in several human cancers. The aim of the present study was to evaluate the expression and prognostic significance of CDT1 and MCM7 in association with DNA damage response markers and p53 in patients with hepatocellular carcinoma.

METHODS

Expression of CDT1, MCM7, p-H2A histone family member X (H2AX), phospho-ataxia telangiectasia-mutated (ATM)/ataxia telangiectasia rad3-related (ATR) substrate, and p53 was evaluated by immunohistochemistry on formalin-fixed paraffin-embedded surgical specimens from 111 patients who underwent hepatectomy for hepatocellular carcinoma. Statistical analysis was performed to evaluate associations between the studied proteins, clinicopathological parameters, and patient survival.

RESULTS

CDT1 expression correlated with p-H2AX (p = 0.038), while MCM7 correlated with p-H2AX and phospho-ATM/ATR substrate (p < 0.001). Increased CDT1 expression was associated with higher tumor grade (p = 0.006) and tumor-node-metastasis (TNM) stage (p = 0.033). High CDT1 expression correlated significantly with reduced overall survival (60.8 and 26.5 % vs 82.8 and 53.0 %, for low CDT1 expression, at 2 and 5 years, respectively, p = 0.012) and was identified by multivariate analysis as an independent predictor of poor overall survival (p = 0.049).

CONCLUSIONS

Overexpression of CDT1 and MCM7 in hepatocellular carcinoma correlates with DNA damage response, and CDT1 overexpression is a significant prognostic biomarker in hepatocellular carcinoma.

Sterigmatocystin-induced checkpoint adaptation depends on Chk1 in immortalized human gastric epithelial cells in vitro

Sterigmatocystin (ST) is a common contaminant detected in food and animal feed that has been recognized as a possible human carcinogen. Our previous studies demonstrate that ST causes DNA damage and subsequently triggers cell cycle arrest in G₂ and apoptosis in immortalized human gastric epithelial cells (GES-1). Recently, studies have shown that in certain contexts, cells with DNA damage may escape checkpoint arrest and enter mitosis without repairing the damage. The term for this process is "checkpoint adaptation," and it increases the risk of unstable genome propagation, which may contribute to carcinogenesis. Thus, we aimed to investigate whether checkpoint adaptation occurs in GES-1 cells treated with ST and explored the underlying molecular mechanisms that contribute to this phenotype. In this study, we found that ST treatment for 24 h in GES-1 cells led to an initial G₂ arrest; however, a fraction of GES-1 cells became large and rounded, and the number of p-H3-positive cells increased sharply after ST treatment for 48 h. Moreover, collection of the large and rounded cells by mechanical shake-off revealed that the majority of these large cells were found in the mitotic phase of the cell cycle. Importantly, we found that these rounded cells entered mitosis despite damaged DNA and that a small subset of this cell population survived and continued to propagate. These results suggest that ST induces an initial G₂ arrest that is subsequently followed by G₂ phase checkpoint adaptation, which may potentially promote genomic instability and result in tumorigenesis. Furthermore, we showed that activation of Chk1 contributes to the G₂ arrest in GES-1 cells that are treated with ST for 24 h and that prolonged treatment of cells with ST for 48 h led to a decrease in the total protein and phosphorylation levels of Chk1 in mitotic cells, indicating that checkpoint adaptation may be driven by inactivation of Chk1. Knockdown studies confirmed that cells entered mitosis following inactivation of Chk1. Taken together, we show that ST treatment for 24 h activates Chk1 and induces a G₂ arrest in GES-1 cells. However, prolonged ST treatment for 48 h led to Chk1 inactivation in GES-1 cells, which promotes checkpoint adaptation and entry of cells into mitosis despite damaged DNA. Importantly, checkpoint adaptation in GES-1 cells treated with ST may potentially promote genomic instability and drive tumorigenesis.

Possible Involvement of Hepatitis B Virus Infection of Hepatocytes in the Attenuation of Apoptosis in Hepatic Stellate Cells

Background

The induction of apoptosis in hepatic stellate cells (HSCs) is a promising therapeutic strategy against hepatitis B virus (HBV)-related hepatic fibrosis. The underlying mechanisms of apoptosis in HSCs, however, are unknown under consideration of HBV infection. In this study, the effects of HBV on apoptosis and endoplasmic reticulum (ER) stress signaling in HSCs were examined.

Methods

The effects of conditioned media (CM) from HepG2.2.15 on apoptosis induced by the proteasome inhibitor MG132 in LX-2 and HHSteC were studied in regard to c-Jun. In combination with c-Fos, c-Jun forms the AP-1 early response transcription factor, leading to AP-1 activation, signal transduction, endoplasmic reticulum (ER) stress and apoptosis.

Results

In LX-2 cells, MG132 treatment was associated with the phosphorylation of c-Jun, activation of AP-1 and apoptosis. However, in the presence of CM from HepG2.2.15, these phenomena were attenuated. In HHSteC cells, similar results were observed. HBV genomic DNA is not involved in the process of HSC apoptosis. It is possible that HBeAg has an inhibitory effect on MG132-induced apoptosis in LX-2. We also observed the upregulation of several ER stress-associated genes, such as cAMP responsive element binding protein 3-like 3, inhibin-beta A and solute carrier family 17-member 2, in the presence of CM from HepG2.2.15, or CM from PXB cells infected with HBV.

Conclusions

HBV inhibits the activation of c-Jun/AP-1 in HSCs, contributing to the attenuation of apoptosis and resulting in hepatic fibrosis. HBV also up-regulated several ER stress genes associated with cell growth and fibrosis. These mechanistic insights might shed new light on a treatment strategy for HBV-associated hepatic fibrosis.

γ-H2AX promotes hepatocellular carcinoma angiogenesis via EGFR/HIF-1α/VEGF pathways under hypoxic condition

Hepatocellular carcinoma (HCC) is one of the most deadly cancers. Using mRNA microarray analysis, we found that H2AX decreased under hypoxic conditions. Hypoxia is an important physiological and pathological stress that induces H2AX phosphorylation (γ-H2AX), but the regulatory mechanism of γ-H2AX remains elusive in the progress of HCC. We report here that increased γ-H2AX expression in HCC is associated with tumor size, vascular invasion, TNM stage and reduced survival rate after liver transplantation (LT). γ-H2AX knockdown was able to effectively inhibit VEGF expression in vitro and tumorigenicity and angiogenesis of HCC in vivo. The mechanism of γ-H2AX on the angiogenic activity of HCC might go through EGFR/HIF-1α/VEGF pathways under hypoxic conditions. Combined γ-H2AX, HIF-1α and EGFR has better prognostic value for HCC after LT. This study suggests that γ-H2AX is associated with angiogenesis of HCC and γ-H2AX or a combination of γ-H2AX/EGFR/HIF-1α is a novel marker in the prognosis of HCC after LT and a potential therapeutic target.

DNA damage response and sphingolipid signaling in liver diseases

Patients with unresectable hepatocellular carcinoma (HCC) cannot generally be cured by systemic chemotherapy or radiotherapy due to their poor response to conventional therapeutic agents. The development of novel and efficient targeted therapies to increase their treatment options depends on the elucidation of the molecular mechanisms that underlie the pathogenesis of HCC. The DNA damage response (DDR) is a network of cell-signaling events that are triggered by DNA damage. Its dysregulation is thought to be one of the key mechanisms underlying the generation of HCC. Sphingosine-1-phosphate (S1P), a lipid mediator, has emerged as an important signaling molecule that has been found to be involved in many cellular functions. In the liver, the alteration of S1P signaling potentially affects the DDR pathways. In this review, we explore the role of the DDR in hepatocarcinogenesis of various etiologies, including hepatitis B and C infection and non-alcoholic steatohepatitis. Furthermore, we discuss the metabolism and functions of S1P that may affect the hepatic DDR. The elucidation of the pathogenic role of S1P may create new avenues of research into therapeutic strategies for patients with HCC.

Cytoglobin deficiency promotes liver cancer development from hepatosteatosis through activation of the oxidative stress pathway

This study was conducted to clarify the role of cytoglobin (Cygb), a globin expressed in hepatic stellate cells (HSCs), in the development of liver fibrosis and cancer in nonalcoholic steatohepatitis (NASH). Cygb expression was assessed in patients with NASH and hepatocellular carcinoma. Mouse NASH model was generated in Cygb-deficient (Cygb(-/-)) or wild-type (WT) mice by giving a choline-deficient amino acid-defined diet and, in some of them, macrophage deletion and N-acetyl cysteine treatment were used. Primary-cultured mouse HSCs isolated from WT (HSCs(Cygb-wild)) or Cygb(-/-) (HSCs(Cygb-null)) mice were characterized. As results, the expression of CYGB was reduced in patients with NASH and hepatocellular carcinoma. Choline-deficient amino acid treatment for 8 weeks induced prominent inflammation and fibrosis in Cygb(-/-) mice, which was inhibited by macrophage deletion. Surprisingly, at 32 weeks, despite no tumor formation in the WT mice, all Cygb(-/-) mice developed liver cancer, which was ameliorated by N-acetyl cysteine treatment. Altered expression of 31 genes involved in the metabolism of reactive oxygen species was notable in Cygb(-/-) mice. Both HSCs(Cygb-null) and Cygb siRNA-transfected-HSCs(Cygb-wild) exhibited the preactivation condition. Our findings provide important insights into the role that Cygb, expressed in HSCs during liver fibrosis, plays in cancer development with NASH.

Abnormal Expression of DNA Double-Strand Breaks Related Genes, ATM and GammaH2AX, in Thyroid Carcinoma

ATM and γH2AX play a vital role in the detection of DNA double-strand breaks (DSB) and DNA damage response (DDR). This study aims to investigate ATM and γH2AX expression in thyroid cancer and discuss possible relationship between thyroid function tests and DNA damage. The expression of ATM and γH2AX was detected by immunohistochemistry in 30 cases of benign nodular goiter, 110 cases of well differentiated thyroid cancer, 22 cases of poorly differentiated thyroid cancer, and 21 cases of anaplastic thyroid cancer. Clinicopathological features, including differentiation stages, distant metastasis, lymph node metastasis, T classification, TNM stage, and tests of thyroid functions (TPOAb, Tg Ab, T3, FT3, T4, FT4, TSH, and Tg), were reviewed and their associations with γH2AX and ATM were analyzed. γH2AX and ATM expressed higher in thyroid cancer tissues than in benign nodular goiter and normal adjacent tissues. γH2AX was correlated with ATM in thyroid cancer. Both γH2AX and ATM expression were associated with FT3. γH2AX was also associated with T classification, TNM stage, FT4, TSH, and differentiation status. Therefore both of ATM and γH2AX seem to correlate with thyroid hormones and γH2AX plays a role in the differentiation status of thyroid cancer.

DNA-PK-A candidate driver of hepatocarcinogenesis and tissue biomarker that predicts response to treatment and survival

PURPOSE

Therapy resistance and associated liver disease make hepatocellular carcinomas (HCC) difficult to treat with traditional cytotoxic therapies, whereas newer targeted approaches offer only modest survival benefit. We focused on DNA-dependent protein kinase, DNA-PKcs, encoded by PRKDC and central to DNA damage repair by nonhomologous end joining. Our aim was to explore its roles in hepatocarcinogenesis and as a novel therapeutic candidate.

EXPERIMENTAL DESIGN

PRKDC was characterized in liver tissues from of 132 patients [normal liver (n = 10), cirrhotic liver (n = 13), dysplastic nodules (n = 18), HCC (n = 91)] using Affymetrix U133 Plus 2.0 and 500 K Human Mapping SNP arrays (cohort 1). In addition, we studied a case series of 45 patients with HCC undergoing diagnostic biopsy (cohort 2). Histological grading, response to treatment, and survival were correlated with DNA-PKcs quantified immunohistochemically. Parallel in vitro studies determined the impact of DNA-PK on DNA repair and response to cytotoxic therapy.

RESULTS

Increased PRKDC expression in HCC was associated with amplification of its genetic locus in cohort 1. In cohort 2, elevated DNA-PKcs identified patients with treatment-resistant HCC, progressing at a median of 4.5 months compared with 16.9 months, whereas elevation of activated pDNA-PK independently predicted poorer survival. DNA-PKcs was high in HCC cell lines, where its inhibition with NU7441 potentiated irradiation and doxorubicin-induced cytotoxicity, whereas the combination suppressed HCC growth in vitro and in vivo.

CONCLUSIONS

These data identify PRKDC/DNA-PKcs as a candidate driver of hepatocarcinogenesis, whose biopsy characterization at diagnosis may impact stratification of current therapies, and whose specific future targeting may overcome resistance.

Imaging DNA damage allows detection of preneoplasia in the BALB-neuT model of breast cancer

A prominent feature of many human cancers is oncogene-driven activation of the DNA damage response (DDR) during early tumorigenesis. It has been shown previously that noninvasive imaging of the phosphorylated histone H2A variant H2AX, γH2AX, a DNA damage signaling protein, is possible using (111)In-labeled anti-γH2AX antibody conjugated to the cell-penetrating peptide transactivator of transcription (TAT). The purpose of this study was to investigate whether (111)In-anti-γH2AX-TAT detects the DDR during mammary oncogenesis in BALB-neuT mice.

METHODS

Mammary fat pads from BALB-neuT and wild-type mice (age, 40-106 d) were immunostained for γH2AX. (111)In-anti-γH2AX-TAT or a control probe was administered intravenously to BALB-neuT mice. SPECT was performed weekly and compared with tumor detection using palpation and dynamic contrast-enhanced MR imaging.

RESULTS

γH2AX expression was elevated in hyperplastic lesions in the mammary fat pads of BALB-neuT mice aged 76-106 d, compared with normal fat pads from younger mice and carcinomas from older mice (13.5 ± 1.2 γH2AX foci/cell vs. 5.2 ± 1.5 [P < 0.05] and 3.4 ± 1.1 [P < 0.001], respectively). Serial SPECT imaging revealed a 2.5-fold increase in (111)In-anti-γH2AX-TAT accumulation in the mammary fat pads of mice aged 76-106 d, compared with control probe (P = 0.01). The median time to detection of neoplastic lesions by (111)In-anti-γH2AX-TAT (defined as >5% injected dose per gram of tissue) was 96 d, compared with 120 and 131 d for dynamic contrast-enhanced MR imaging and palpation, respectively (P < 0.001).

CONCLUSION

DDR imaging using (111)In-anti-γH2AX-TAT identified mammary tumors significantly earlier than MR imaging. Imaging the DDR holds promise for the detection of preneoplasia and as a technique for screening cancer-prone individuals.

X-ray and ultraviolet C irradiation-induced γ-H2AX and p53 formation in normal human periosteal cells in vitro: markers for quality control in cell therapy

BACKGROUND AIMS

For successful cell transplantation therapy, the quality of cells must be strictly controlled. Unfortunately, to exclude inappropriate cells that possess structurally abnormal chromosomes, currently only karyotyping functions as an assessment. Unfortunately, this methodology is time-consuming and only effective for metaphasic cells. To develop a more efficient, inclusive and sensitive methodology, we examined the phosphorylation of histone H2AX and the p53 levels in normal human periosteal cells exposed to x-rays or other oxidative stressors.

METHODS

Periosteal cells were obtained from human alveolar bone before being exposed to x-rays, ultraviolet C or hydrogen peroxide. The cell cycle, electric nuclear volume and CD44 expression were evaluated using flow cytometry, and the phosphorylated H2AX (γ-H2AX), p53, p21 and proliferating cell nuclear antigen (PCNA) levels were evaluated by Western blot analyses.

RESULTS

Each oxidative stress dose-dependently arrested cell growth and partially induced premature cellular senescence. In parallel, each oxidative stress rapidly phosphorylated H2AX and stabilized p53, and intense stress sustained these high levels for at least 8 days.

CONCLUSIONS

Intensive oxidative stress induces sustained high levels of γ-H2AX and p53, which force cells toward senescence or non-apoptotic cell death. Lower doses of oxidative stress induced more modest and transient increases in γ-H2AX and p53, and these cells eventually survive. However, because DNA is repaired without a template in the majority of these cells, G1 mutations accumulate. Therefore, we recommend that any cell population expressing elevated γ-H2AX and p53 levels be excluded from cell transplantation therapy.

Involvement of DNA damage response pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has been known as one of the most lethal human malignancies, due to the difficulty of early detection, chemoresistance, and radioresistance, and is characterized by active angiogenesis and metastasis, which account for rapid recurrence and poor survival. Its development has been closely associated with multiple risk factors, including hepatitis B and C virus infection, alcohol consumption, obesity, and diet contamination. Genetic alterations and genomic instability, probably resulted from unrepaired DNA lesions, are increasingly recognized as a common feature of human HCC. Dysregulation of DNA damage repair and signaling to cell cycle checkpoints, known as the DNA damage response (DDR), is associated with a predisposition to cancer and affects responses to DNA-damaging anticancer therapy. It has been demonstrated that various HCC-associated risk factors are able to promote DNA damages, formation of DNA adducts, and chromosomal aberrations. Hence, alterations in the DDR pathways may accumulate these lesions to trigger hepatocarcinogenesis and also to facilitate advanced HCC progression. This review collects some of the most known information about the link between HCC-associated risk factors and DDR pathways in HCC. Hopefully, the review will remind the researchers and clinicians of further characterizing and validating the roles of these DDR pathways in HCC.