Proliferating Cellular Nuclear Antigen Research Articles

Cytotoxic Potential of Novel Quinoline Derivative: 11-(1,4-Bisaminopropylpiperazinyl)5-methyl-5H-indolo[2,3-b]quinoline against Different Cancer Cell Lines via Activation and Deactivation of the Expression of Some Proteins.

The current study evaluated the cytotoxic activity of 11-(1,4-bisaminopropylpiperazinyl)5-methyl-5H-indolo[2,3-b]quinoline (BAPPN), a novel derivative of 5-methyl-5H-indolo[2,3-b]quinoline, against hepatocellular carcinoma (HepG2), colon carcinoma (HCT-116), breast (MCF-7), and lung (A549) cancer cell lines and the possible molecular mechanism through which it exerts its cytotoxic activity. BAPPN was synthesized and characterized with FT-IR and NMR spectroscopy. The binding affinity scores of BAPPN for caspase-3 PDB: 7JL7 was -7.836, with an RMSD of 1.483° A. In silico screening of ADME properties indicated that BAPPN showed promising oral bioavailability records in addition to their high gastrointestinal absorption and blood-brain barrier penetrability. BAPPN induced cytotoxicity, with IC50 values of 3.3, 23, 3.1, and 9.96 μg/mL against cancer cells HepG2, HCT-116, MCF-7, and A549, respectively. In addition, it induced cell injury and morphological changes in ultracellular structure, including cellular delayed activity, vanishing of membrane blebbing, microvilli, cytoplasmic condensation, and shrunken nucleus with more condensed chromatin autophagosomes. Furthermore, BAPPN significantly increased the protein expression of caspase-3 and tumor suppressor protein (P53). However, it significantly reduced the secretion of vascular endothelial growth factor (VEGF) protein into the medium and decreased the protein expression of proliferation cellular nuclear antigen (PCNA) and Ki67 in HepG2, HCT-116, MCF-7, and A549 cells. This study indicates that BAPPN has cytotoxic action against liver, colon, breast, and lung cancer cell lines via the up-regulation of apoptotic proteins, caspase-3 and P53, and the downregulation of proliferative proteins, VEGF, PCNA, and Ki67.

Production of recombinant human proliferating cellular nuclear antigen (PCNA) for structural and biophysical characterization

Human proliferating cell nuclear antigen (hPCNA) is a DNA replication processivity factor, which acts as a docking platform, allowing proteins to have access to the replication fork and increasing the affinity of DNA interacting proteins, making it critical for cell survival. The trimer forms a ring-shaped oligomer allowing DNA to pass through the middle and interacting proteins to dock on the outside of the ring. Without this structural formation, there is a loss of DNA replication and repair in the cell. Due to the location of subunit-subunit termini, the addition of a purification tag can hamper crystallography and biophysical experiments, as the trimer complex folding can be impeded. To avoid these complications, a tag-less, step-wise purification was implemented, which resulted in 17.6 mg from 2 L culture of pure hPCNA with a 260 nm/280 nm value of 0.43. The produced crystal structure reveals a correctly formed oligomer. The clear depletion of the tracer binding and probe protein interaction in a fluorescence polarisation competition-based assay demonstrates the purification method produces a protein structure with a functional binding site. This purification method presents a reliable and simple method for producing hPCNA for biophysical characterisation.

Mechanism of sliding clamp loading during DNA replication and repair in atomic detail.

DNA replication is essential for all life. Efficient and fast replication is promoted by ring-shaped sliding clamp proteins. Moreover, the eukaryotic clamp, Proliferating Cellular Nuclear Antigen (PCNA) coordinates several other cellular pathways, including DNA repair. PCNA's role as the central hub for pathways that maintain genome stability makes its proper function important to human health. The main regulator of sliding clamp is the clamp loader AAA+ ATPase. The eukaryotic loader, Replication Factor C (RFC), opens the closed PCNA and loads it onto DNA. Despite years of study, it was unclear how RFC opens PCNA and subsequently binds DNA. To address this, we used single particle cryoEM to reconstruct multiple structures of the RFC:PCNA complex that delineate the steps in the clamp loading reaction, ranging from the first encounter complex to intermediates with PCNA loaded onto primer-template DNA without ATP hydrolysis. We observe that RFC opens PCNA with a ‘crab-claw-like’ motion that enables RFC to prefer PCNA binding before DNA. Furthermore, primer-template DNA, RFC's primary DNA substrate during replication, binds directly to the central chamber of the complex. However, this structure did not tell us how the complex binds to other DNA substrates, such as nicked or gapped DNA for DNA repair. Thus, we also determined structures of RFC:PCNA bound to those DNA and discovered a second DNA binding site. Both DNA binding sites contain ‘separation pins’ that melt DNA without ATP hydrolysis to provide the flexibility required for DNA binding. This is the first structural insight into how PCNA can accomplish its dual roles in DNA repair and replication, and is supported by our biochemical and cellular studies. In all, our study shows how a AAA+ ATPase can load sliding clamps at a variety of DNA architectures.

Abstract 803: Identifying a RAD18/UBC13-dependent mechanism of replication fork recovery to modulate chemoresponse in BRCA1-deficient cancers

Abstract Mutations in the breast cancer susceptibility genes BRCA1 and BRCA2 are associated with an increased lifetime risk of breast and ovarian cancers. While the BRCA proteins play a well-established role in double-stranded DNA break repair, recent studies have revealed an emerging role of BRCA1/2 in replication stress response. While replication forks are extensively degraded by nucleases in BRCA-deficient cancer cells, activation of specialized fork recovery mechanisms enables resumption of DNA synthesis and promotes cell survival. My project aims to determine this fork recovery mechanism in BRCA1-deficient cells and to identify potential recovery factors that can be targeted to improve chemotherapeutic response in BRCA1-mutated breast and ovarian cancers. To monitor perturbations in replication fork dynamics on a genome-wide scale, we utilize a DNA fiber assay technique measuring rates of fork recovery and replication fork degradation. In parallel, electron microscopy analysis allows direct visualization of replication fork intermediates. Cell survival assays are employed to test how loss of fork recovery factors impacts cell proliferation and chemotherapeutic response in BRCA1-deficient cells. Our results reveal that RAD18 and UBC13, which catalyze ubiquitination of Proliferating Cellular Nuclear Antigen (PCNA), promote fork recovery in BRCA1-deficient, but not BRCA2-deficient, cancer cells. Previous work has also shown that PCNA polyubiquitination by UBC13 is important for reversed fork formation in BRCA-proficient cells. However, our findings show that extensive degradation of reversed fork substrates still occurs in BRCA1-deficient cells lacking RAD18 or UBC13, indicating that PCNA polyubiquitination is not essential for fork reversal in this genetic background. In addition, loss of RAD18 in BRCA1-deficient cells significantly slows cell proliferation, and UBC13 inhibition further sensitizes cells lacking BRCA1 to the replication stress inducer Hydroxyurea (HU). Based on our findings, we hypothesize that RAD18, UBC13, and PCNA ubiquitination may represent novel targets to improve chemoresponse in BRCA1-deficient cancers that rely on fork recovery mechanisms for survival. Citation Format: Emily Cybulla, Jessica Jackson, Stephanie Tirman, Annabel Quinet, Delphine Lemacon, Alessandro Vindigni. Identifying a RAD18/UBC13-dependent mechanism of replication fork recovery to modulate chemoresponse in BRCA1-deficient cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 803.

Rutin Ameliorates Hepatic Fibrosis via Targeting Hepatic Stellate Cells’ Activation, Proliferation and Apoptosis

ABSTRACT Despite rutin, extracted from black mulberry, has several pharmacological activities, its exact effect against hepatic fibrosis remains incompletely identified. Accordingly, this study investigates whether rutin is a promising candidate for treating hepatic fibrosis and to clarify its underlying antifibrotic mechanisms in vitro and in vivo. In vitro studies were performed on hepatic stellate cell line (HSC-T6) whereas liver fibrosis was established in rats via chronic thioacetamide (TAA)-intoxication. Rats were divided into (i) normal, (ii) TAA-intoxicated rats; TAA-intoxicated rats treated with (iii) silymarin or (iv) rutin. Levels of ALT, AST, platelet-derived growth factor-BB (PDGF-BB), tissue inhibitor metalloproteinases type-1 (TIMP-1), hydroxyproline and expression of proliferating cellular nuclear antigen (PCNA) together with histological changes were examined. Activities of rutin on TGF-β1, α-smooth muscle actin (α-SMA) and caspase-3 were measured in vitro and in vivo. Rutin exhibited no marked HSC-T6 cell death (IC50 = 460 µg.ml−1), however, it showed reduction in HSCs activation (low TGF-β1 level and α-SMA positive cells) and induced apoptosis (high caspase-3 positive cells). Rutin also ameliorated liver functions, reduced hepatic levels of PDGF-BB, TGF-β1, TIMP-1, hydroxyproline and restored PCNA, together with attenuation in fibrosis score (S1 vs S4). Rutin could be a promising candidate for treating hepatic fibrosis through down-regulation of HSCs activation and induction of apoptosis.

α-Solanine Inhibits Proliferation, Invasion, and Migration, and Induces Apoptosis in Human Choriocarcinoma JEG-3 Cells In Vitro and In Vivo.

α-Solanine, a bioactive compound mainly found in potato, exhibits anti-cancer activity towards multiple cancer cells. However, its effects on human choriocarcinoma have not been evaluated. In the present study, we investigated the effect of α-solanine on cell proliferation and apoptosis in human choriocarcinoma in vitro and in vivo. The results showed that α-solanine, at concentrations of 30 μM or below, did not affect the cell viability of the choriocarcinoma cell line JEG-3. However, colony formation was significantly decreased and cell apoptosis was increased in response to 30 μM α-solanine. In addition, α-solanine (30 μM) reduced the migration and invasion abilities of JEG-3 cells, which was associated with a downregulation of matrix metalloproteinases (MMP)-2/9. The in vivo findings provided further evidence of the inhibition of α-solanine on choriocarcinoma tumor growth. α-Solanine suppressed the xenograft tumor growth of JEG-3 cells, resulting in smaller tumor volumes and lower tumor weights. Apoptosis was promoted in xenograft tumors of α-solanine-treated mice. Moreover, α-solanine downregulated proliferative cellular nuclear antigen (PCNA) and Bcl-2 levels and promoted the expression of Bax. Collectively, α-solanine inhibits the growth, migration, and invasion of human JEG-3 choriocarcinoma cells, which may be associated with the induction of apoptosis.

Hippo pathway inhibition increases YAP activity and augments liver regeneration in murine partial hepatectomy

Presenter: Ryan Watkins MD | Mayo Clinic, Rochester Background: Impaired liver regeneration following hepatectomy is associated with poor outcomes. Augmenting the Hippo pathway effector, Yes-associated protein (YAP), has been associated with improved liver regeneration. We show that YAP transcriptional co-activity is increased by inhibiting MST1/2 with a novel inhibitor mCLC846 (mCLC), leading to improved liver regeneration in murine partial hepatectomy. Methods: Normal human cholangiocyte (NHC) cells were treated with mCLC. Cell viability was evaluated via an ATP based assay and YAP transcriptional co-activity was assessed by quantitative RT-PCR. 12-15-week-old male C57BL/6J mice underwent standard 2/3 partial hepatectomy (PH). Mice were treated with mCLC (5, 15, 50, and 100mg/kg) or vehicle 8-12 hours pre-hepatectomy and then twice daily until euthanasia. Liver regeneration was evaluated by liver to body weight ratio at 40 and 72 hours following PH, proliferation was characterized by immunoblot for proliferating cellular nuclear antigen (PCNA) and quantified by densitometry, and YAP target gene expression by quantitative RT-PCR in whole liver lysates. Additional mice were aged to 34 weeks and then underwent the same experiments as the 12-15 week old mice. Results: NHC cell culture treated with mCLC showed statistically increased cell viability following 72 hours of treatment. YAP target genes Ctgf, Cyr61, and Nuak2 significantly increased following 24 hours of treatment as compared to vehicle treated cells. Mice undergoing PH treated with mCLC showed statistically significant increases in liver to body weight ratio at both 40 and 72 hours following PH. Liver to body weight ratio at 72 hours increased as mCLC doses increased from 5 to 100 mg/kg. YAP target genes Ctgf, Cyr61 and Ankrd1 in liver lysates 40 hours post hepatectomy were significantly compared to controls. PCNA levels 40 hours following PH were 5 fold higher when compared to vehicle treated mice. Aged mice have impaired regeneration as indicated by the liver to body weight ratio at 72 hours. Aged mice treated with mCLC resulted in significant increases in liver to body weight ratio when compared to both vehicle treated mice and the vehicle treated standard cohort. Conclusion: Our data suggests that inhibiting MST1/2 with mCLC leads to cholangiocyte proliferation and increased YAP co-transcriptional activity. Additionally, MST1/2 inhibition causes an increase in whole liver YAP activity, increased cellular proliferation, and accelerated liver regeneration in murine partial hepatectomy. Aged mice have impaired regenerative capacity following hepatectomy however, mCLC remains efficacious in promoting liver regeneration.

Vitamin E and selenium administration synergistically mitigates ivermectin and doramectin-induced testicular dysfunction in male Wistar albino rats

Avermectins are broad-spectrum antiparasitic drugs in veterinary and human medication. The current study aimed to examine the toxic effects of ivermectin (IVM) and doramectin (DRM), with or without co-treatment of vitamin E (Vit.E) and selenium (Se) on apoptosis, oxidative stress and male fertility in Wistar rats. Twenty five adult male animals were divided into five groups; G1; was control (CTL) received saline, G2; IVM (0.2 mg/kg b.w), G3; IVM plus Vit.E/Se (80/1.6 mg/kg b.w, respectively), G4; DRM (0.2 mg/kg b.w), and G5; DRM plus Vit.E/Se. Both IVM and DRM were given by subcutaneous (s.c) injections while Vit.E/Se was orally given. All treatments were administered once weekly for four consecutive weeks. By 24 h after the last treatment, the animals were sacrificed. Blood and tissue samples were collected for hematology, serobiochemistry, histopathology, and molecular assays for hepatic/ renal toxicities, oxidative stress, cell viability and fertility parameters. Apoptosis of the hepatic cells obtained from the treated rats was assayed by detection of annexin-V using the flow cytometric assay (FCA). The proliferating cellular nuclear antigen (PCNA) and DNA fragmentation in the treated rats’ testicular tissues were also assayed. Moreover, the direct effects of IVM or DRM with or without concomitant administration of Vit.E/Se on testicular cells isolated from adult rat were also performed in vitro. Apoptosis of those cultured testicular cells in response to the different treatments was assayed by detection of the inhibition-concentration fifty (IC50) using the SRB method, and evaluating the viable versus apoptotic cells microscopically after staining with acridine orange-ethidium bromide (AO/EB). In conclusion, both avermectins induced apoptosis in the living and cultured cells, while those antioxidants; Vit.E and Se, reduced the oxidative stress and cytotoxicity both in vivo and in vitro, either. Furthermore, the reprotoxicity and reduced male fertility were seriously evoked by IVM, but not DRM with dramatic ameliorative effect of Vit.E/Se if concomitantly administered. Avermectins, especially ivermectin, should be given according to the dose recommended by the manufacturer company and repeated dosages should be given with Vit.E/Se.

Tisp40 deficiency limits renal inflammation and promotes tubular cell proliferation in renal ischemia reperfusion injury

Renal ischemia reperfusion (IR) is a common cause of acute kidney injury (AKI), and no effective treatment is available to date. In our previous studies, we demonstrated that Tisp40 exacerbates tubular cell apoptosis and tubulointerstitial fibrosis after renal IR injury. However, the role of Tisp40 in renal inflammatory responses and tubular cell proliferation during renal IR injury remains unknown. In this study, Tisp40 knockout (KO) and wild-type (WT) mice were induced with or without renal IR injury. For renal IR, bilateral renal pedicels were exposed and clamped to induce 30 min of ischemia. After 48 h of reperfusion, the kidneys were collected for analyses. Results showed that Tisp40 deficiency attenuates neutrophil and macrophage infiltration after renal IR. Consistently, the protein levels of TNF-α and MCP-1 were markedly decreased, and the phosphorylation levels of IκBα and P65 were inhibited in Tisp40-deficient mice than in WT mice in renal IR injury. In addition, compared with WT mice, Tisp40 deficiency significantly increased the expression levels of proliferative cellular nuclear antigen and phosphorylated Erk1/2 after renal IR injury. In conclusion, Tisp40 deficiency limits renal inflammatory responses and promotes tubular cell proliferation in ischemic AKI.

The Fibrin Cleavage Product Bβ15-42 Channels Endothelial and Tubular Regeneration in the Post-acute Course During Murine Renal Ischemia Reperfusion Injury.

Early and adequate restoration of endothelial and tubular renal function is a substantial step during regeneration after ischemia reperfusion (IR) injury, occurring, e.g., in kidney transplantation, renal surgery, and sepsis. While tubular epithelial cell injury has long been of central importance, recent perception includes the renal vascular endothelium. In this regard, the fibrin cleavage product fibrinopeptide Bβ15-42 mitigate IR injury by stabilizing interendothelial junctions through its affinity to VE-cadherin. Therefore, this study focused on the effect of Bβ15-42 on post-acute physiological renal regeneration. For this, adult male C57BL/6 mice were exposed to a 30 min bilateral renal ischemia and reperfusion for 24 h or 48 h. Animals were randomized in a non-operative control group, two operative groups each treated with i.v. administration of either saline or Bβ15-42 (2.4 mg/kg) immediately prior to reperfusion. Endothelial activation and inflammatory response was attenuated in renal tissue homogenates by single application of Bβ15-42. Meanwhile, Bβ15-42 did not affect acute kidney injury markers. Regarding the angiogenetic players VEGF-A, Angiopoietin-1, Angiopoietin-2, however, we observed significant higher expressions at mRNA and trend to higher protein level in Bβ15-42 treated mice, compared to saline treated mice after 48 h of IR, thus pointing toward an increased angiogenetic activity. Similar dynamics were observed for the intermediate filament vimentin, the cytoprotective protein klotho, stathmin and the proliferation cellular nuclear antigen, which were significantly up-regulated at the same points in time. These results suggest a beneficial effect of anatomical contiguously located endothelial cells on tubular regeneration through stabilization of endothelial integrity. Therefore, it seems that Bβ15-42 represents a novel pharmacological approach in the targeted therapy of acute renal failure in everyday clinical practice.

Antifibrotic effects of gallic acid on hepatic stellate cells: In vitro and in vivo mechanistic study

Few studies reported the antifibrotic effects of gallic acid (GA) despite its known hepatoprotective and antioxidant activities. Accordingly, this study investigated the antifibrotic effects of GA through clarifying its mechanisms on hepatic stellate cells' (HSCs) activation, proliferation and/or apoptosis. In vitro effects of GA on HSC-T6 activation/proliferation, morphology and safety on hepatocytes were assessed. In vivo, hepatic fibrosis was induced via chronic thioacetamide (TAA)-intoxication. TAA-intoxicated rats were treated with silyamrin or GA. At end of experiment, liver functions, hepatic MDA, GSH, PDGF-BB, TGF-β1, TIMP-1 and hydroxyproline were determined. Histological analysis and Sirius red staining of hepatic sections, expressions of alpha-smooth muscle actin (α-SMA), proliferating cellular nuclear antigen (PCNA) and caspase-3 were examined. In vitro, GA resulted in a concentration and time-dependent inhibition in HSCs activation, proliferation (IC50= 45 and 19 μg/mL at 24 and 48 h respectively); restored the quiescent morphology of some activated HSCs plus its safety on hepatocytes. In vivo, GA reduced ALT, AST, MDA, PDGF-BB levels, collagen deposition and fibrosis score (S1 vs S4); increased caspase-3 expression and restored GSH stores, TGF-β1 level, α-SMA and PCNA expressions. In conclusion, GA counteracted the progression of hepatic fibrosis through reduction of HSCs proliferation/activation mutually with their apoptosis induction.

Myeloperoxidase modification of high-density lipoprotein suppresses human endothelial cell proliferation and migration via inhibition of ERK1/2 and Akt activation

Background and aimsPreclinical studies show high-density lipoproteins (HDL) have a protective and reparative effect on the endothelium. HDL is, however, susceptible to oxidation, which affects function. Myeloperoxidase (MPO)-induced modification of HDL results in loss of anti-apoptotic and anti-inflammatory functions, however, its effect on endothelial proliferation and migration has not been characterized. MethodsHUVECs were co-incubated with MPO-oxidised- or native-HDL (nHDL) in proliferation and migration assays. Signalling proteins were assessed in Western blots. ResultsnHDL caused dose-dependent increases of endothelial proliferation and migration. Consistent with an increase in cellular proliferation, HDL also stimulated proliferative cellular nuclear antigen (PCNA) expression and ERK phosphorylation in a concentration-dependent manner, which did not occur with MPO-oxidised HDL. HDL increased Akt phosphorylation, a driver of cellular migration. Contrastingly, MPO-oxidised HDL was unable to increase Akt phosphorylation and extensively-oxidised HDL inhibited Akt phosphorylation. ConclusionsHDL promotes endothelial proliferation and migration, mediated in part via activation of ERK and Akt signalling. MPO-induced oxidative modification of HDL attenuates the endothelial-protective effects of HDL. These findings suggest that in an oxidative milieu, present in ageing and disease, HDL is likely to become ineffective. This has implications for HDL-raising therapies and emphasizes the need for strategies that prevent oxidation-related HDL dysfunction.

Analysis of H3K27me3 expression and DNA methylation at CCGG sites in smoking and non-smoking patients with non-small cell lung cancer and their clinical significance.

Smoking frequently leads to epigenetic alterations, including DNA methylation and histone modifications. The effect that smoking has on the DNA methylation levels at CCGG sites, the expression of trimethylation of histone H3 at lysine 27 (H3K27me3) and enhancer of zeste homolog 2 (EZH2), and their interactions in patients with non-small cell lung cancer (NSCLC) were analyzed. There were a total of 42 patients with NSCLC, 22 with adenocarcinomas and 20 with squamous cell carcinomas enrolled in the present study. Expression of H3K27me3, EZH2 and proliferating cellular nuclear antigen (PCNA) were immunohistochemically detected. DNA methylation at CCGG sites was evaluated via histoendonuclease-linked detection of DNA methylation sites. The apoptotic index of cancerous tissues obtained from patients of different smoking statuses was evaluated via the terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labeling method. The association with clinicopathological data was calculated relative to different smoking statuses. Compared with the non-smokers, smokers with NSCLC exhibited a significantly lower apoptotic index (P<0.05), and frequently had a lower level of DNA methylation at CCGG sites, lower H3K27me3 expression and a higher EZH2 expression (P<0.05). DNA methylation levels at CCGG sites were negatively correlated to the Brinkman index (P=0.017). Furthermore, there was a parallel association between the H3K27me3 and EZH2 expression levels in the majority of smokers, whereas in the majority of non-smokers, there was a diverging association (P=0.015). There was a diverging association between the PCNA and EZH2 expression levels in the majority of smokers; however, in the majority of non-smokers, there was a parallel association (P=0.048). In addition, the association between the CCGG methylation ratio and immunohistochemical expression of H3K27me3 was a parallel association in the majority of smokers, while in the majority of non-smokers there was a diverging association (P=0.049). Conclusively, patients with NSCLC and different smoking statuses exhibit different epigenetic characteristics. Additionally, DNA methylation levels at the CCGG sites may have the ability to determine associations between the expression levels of H3K27me3, EZH2 and PCNA.

Rosmarinic acid attenuates hepatic fibrogenesis via suppression of hepatic stellate cell activation/proliferation and induction of apoptosis.

To investigate the antifibrotic role of rosmarinic acid (RA), a natural polyphenolic compound, on HSCs activation/proliferation and apoptosis invitro and invivo. The impact of RA on stellate cell line (HSC-T6) proliferation, activation and apoptosis was assessed along with its safety on primary hepatocytes. Invivo, rats were divided into: (i) normal; (ii) thioacetamide (TAA)-intoxicated rats for 12 weeks; (iii) TAA+silymarin or (iv) TAA+RA. At the end of experiment, liver functions, oxidative stress, inflammatory and profibrogenic markers, tissue inhibitor metalloproteinases type-1 (TIMP-1) and hydroxyproline (HP) levels were evaluated. Additionally, liver histopathology and immunohistochemical examinations of alpha-smooth muscle actin (α-SMA), caspase-3 and proliferation cellular nuclear antigen (PCNA) were determined. RA exhibited anti-proliferative effects on cultured HSCs in a time and concentration dependent manner showing an IC50 of 276μg/mL and 171μg/mL for 24h and 48h, respectively, with morphological reversion of activated stellate cell morphology to quiescent form. It significantly improved ALT, AST, oxidative stress markers and reduced TIMP-1, HP levels, inflammatory markers and fibrosis score (S1 vs S4). Furthermore, reduction in α-SMA plus elevation in caspase-3 expressions of HSCs invitro and invivo associated with an inhibition in proliferation of damaged hepatocytes were recorded. RA impeded the progression of liver fibrosis through inhibition of HSCs activation/proliferation and induction of apoptosis with preservation of hepatic architecture.

Destabilization of the PCNA trimer mediated by its interaction with the NEIL1 DNA glycosylase.

The base excision repair (BER) pathway repairs oxidized lesions in the DNA that result from reactive oxygen species generated in cells. If left unrepaired, these damaged DNA bases can disrupt cellular processes such as replication. NEIL1 is one of the 11 human DNA glycosylases that catalyze the first step of the BER pathway, i.e. recognition and excision of DNA lesions. NEIL1 interacts with essential replication proteins such as the ring-shaped homotrimeric proliferating cellular nuclear antigen (PCNA). We isolated a complex formed between NEIL1 and PCNA (±DNA) using size exclusion chromatography (SEC). This interaction was confirmed using native gel electrophoresis and mass spectrometry. Stokes radii measured by SEC hinted that PCNA in complex with NEIL1 (±DNA) was no longer a trimer. Height measurements and images obtained by atomic force microscopy also demonstrated the dissociation of the PCNA homotrimer in the presence of NEIL1 and DNA, while small-angle X-ray scattering analysis confirmed the NEIL1 mediated PCNA trimer dissociation and formation of a 1:1:1 NEIL1-DNA-PCNA(monomer) complex. Furthermore, ab initio shape reconstruction provides insights into the solution structure of this previously unreported complex. Together, these data point to a potential mechanistic switch between replication and BER.

Resistin-Like Molecule-α Causes Lung Injury in Rats with Acute Pancreatitis by Activating the PI-3K/Akt-NF-κB Pathway and Promoting Inflammatory Cytokine Release.

Resistin-like molecule-α (RELMα) has diverse regulatory functions in inflammation, but its role in severe acute pancreatitis (SAP) and acute pancreatitis associated lung injury (APALI) remains unclear. SAP was induced in rats. RELMα protein expression was detected in lung tissue of rats to determine the relationship between APALI and RELMα. To investigate the effect of RELMα overexpression or knockdown on APALI, rats were given an intravenous injection of adenovirus vector before SAP induction. Lung and pancreatic samples were harvested 16 h after induction. After detection of RELMα protein levels, the severity of pancreatic and pulmonary injury was scored histologically, and serum and tissue levels of inflammatory mediators were measured. TUNEL assay and immunofluorescence were used to estimate pulmonary apoptosis and endothelial barrier integrity in lung tissue of SAP rats with RELMα knockdown. RELMα expression was significantly up-regulated in APALI and was related to the lung injury index. RELMα overexpression aggravated the release of inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, and serum C-reaction protein; the expression of inflammatory mediators phosphorylated (p)-AKT, p-P65, p-P38 mitogen activated protein kinase, p-extracellular regulated kinase, and intracellular adhesion molecule-1; and lung injury. RELMα knockdown had opposite effects. In addition, RELMα knockdown improved expression of proliferative cellular nuclear antigen, Bcl-2, zonal occluding-1 and Claudin-1 in lung tissue of SAP rats. RELMα is associated with lung injury severity in SAP. RELMα augments inflammatory activity by increasing inflammatory cytokine release.

Gestation-related gene expression and protein localization in endometrial tissue of Suffolk and Cheviot ewes at gestation Day 19, after transfer of Suffolk or Cheviot embryos

The objective of this study was to investigate the gene expression of progesterone and estrogen receptor α (PR, ERα), insulin-like growth factor (IGF) 1, IGF-2, their receptor (IGFR1), IGF-binding proteins (BP) 1 to 6, insulin receptor, adiponectin receptors (AdipoR1/2), cyclooxygenase 2 (PTGS2), mucin 1 and to localize PR, ERα, IGF-1, IGFR1, PTGS2, and proliferating cellular nuclear antigen (PCNA) in the endometrium of pregnant (Day 19) Suffolk and Cheviot ewes carrying Suffolk and Cheviot embryos transferred within and reciprocally between breeds. Gene expression was determined by real-time quantitative polymerase chain reaction (RT-qPCR), and antigen determination was measured by immunohistochemistry in the luminal epithelium (LE), superficial and deep glands (SG, DG, respectively) and superficial and deep stroma. Gene expression of PR, IGF-1, IGFBP2, and IGFBP5 was higher in Suffolk than that in Cheviot ewes (P < 0.05). Greater abundance of IGF-2 and IGBP3 expression was found in Cheviot ewes carrying Cheviot embryos than Cheviot ewes carrying Suffolk embryos (P < 0.05). No staining for PR and ERα was observed in the LE, very scarce staining in SG and DG, whereas positive staining was observed in both superficial and deep stroma. No differences were found for PR staining, but Cheviot ewes had higher ERα staining intensity than Suffolk ewes (P < 0.05). Positive staining for IGF-1 was observed in all cell types except DG, and staining of IGFR1 was observed in all cell types. No differences among groups in staining were found for IGF-1 or IGFR1 in any cell type. Positive staining of PTGS2 was observed in LE and SG in all groups. An interaction between ewe and embryo breed affected PTGS2 staining (P < 0.05), whereby Cheviot ewes carrying Suffolk embryos had a lower PTGS2 staining than Suffolk ewes carrying Suffolk embryos. Positive staining of PCNA was found in LE and SG. Suffolk ewes carrying Suffolk embryos showed lower PCNA immunostaining than Cheviot ewes carrying Suffolk embryos (P < 0.05), whereas no differences were observed in ewes carrying Cheviot embryos. This study showed that gestation-related protein expression in the endometrium of Suffolk and Cheviot ewes is affected by both ewe and embryo breed at Day 19 of pregnancy.

Arsenic Inhibits DNA Mismatch Repair by Promoting EGFR Expression and PCNA Phosphorylation

Both genotoxic and non-genotoxic chemicals can act as carcinogens. However, while genotoxic compounds lead directly to mutations that promote unregulated cell growth, the mechanism by which non-genotoxic carcinogens lead to cellular transformation is poorly understood. Using a model non-genotoxic carcinogen, arsenic, we show here that exposure to arsenic inhibits mismatch repair (MMR) in human cells, possibly through its ability to stimulate epidermal growth factor receptor (EGFR)-dependent tyrosine phosphorylation of proliferating cellular nuclear antigen (PCNA). HeLa cells exposed to exogenous arsenic demonstrate a dose- and time-dependent increase in the levels of EGFR and tyrosine 211-phosphorylated PCNA. Cell extracts derived from arsenic-treated HeLa cells are defective in MMR, and unphosphorylated recombinant PCNA restores normal MMR activity to these extracts. These results suggest a model in which arsenic induces expression of EGFR, which in turn phosphorylates PCNA, and phosphorylated PCNA then inhibits MMR, leading to increased susceptibility to carcinogenesis. This study suggests a putative novel mechanism of action for arsenic and other non-genotoxic carcinogens.

Sa1687 Modeling Cholangiocarcinoma Desmoplasia for Rapidly Identifying Stromal Targeting Agents

A S L D A b st ra ct s sham or bile duct ligation (BDL) and were then treated with chloroquine (an inhibitor of autophagy; 60 mg/kg/day), rapamycin (an activator of autophagy; 30 mg/kg/day) or recombinant PGRN (5 nmol/kg/day) via intraperitoneal implanted minipump for 3 days. Cholangiocyte proliferation and intrahepatic biliary mass were assessed in vivo by immunohistochemistry using proliferating cellular nuclear antigen (PCNA) or cytokeratin 19 (CK19) antibodies respectively. In vitro, a parental mouse cholangiocyte cell line and cells overexpressing the pro-autophagic effector Sirt1 were treated with chloroquin and rapamycin and PGRN for up to 48 hr and proliferation assessed using MTS assays. Expression of the autophagy markers, Beclin, ATG5, ATG7 and LAMP1, and Sirt1 were assessed by qPCR, immunoblotting and immunohistochemistry in livers and cholangiocytes after the above-mentioned treatments. Autophagy was also assessed in vitro in mouse cholangiocyte cell lines using a commercially available lysotracker staining kit. Results: After BDL, markers of autophagy were increased, specifically in cholangiocytes. Strategies to inhibit autophagy (chloroquine) increased intrahepatic biliary mass and induced cholangiocyte proliferation in vivo and in vitro, whereas strategies to stimulate autophagy (rapamycin) reduced intrahepatic biliary mass after BDL and reduced cholangiocyte proliferation in vivo and in vitro. Treatment with recombinant PGRN reduced the expression of autophagy markers in cholangiocytes and increased cholangiocyte proliferation. Associated with these effects was a PGRN-induced suppression of the pro-autophagic molecule, Sirt1. Indeed, the inhibitory effect of PGRN on autophagy was alleviated in cholangiocytes overexpressing Sirt1. Conclusion: Our data suggest that autophagy is upregulated during hyperplastic cholangiocyte proliferation, presumably as a compensatory mechanism to prevent overt proliferation. Furthermore, PGRN may induce cholangiocyte proliferation by inhibiting autophagy via the suppression of Sirt1 expression.

Anti-cell Proliferative, Anti-inflammatory and Anti-angiogenic Potential of Lupeol in 7,12-dimethylbenz(a) Anthracene Induced Hamster Buccal Pouch Carcinogenesis

Aim: Diverse pharmacological and biochemical effects of lupeol have been reported earlier. The present study utilized the immune expression pattern of proliferating cellular nuclear antigen (PCNA), cyclin D1, vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2) and nuclear factor kappa B (NFkB) to assess the anticancer potential of lupeol in 7,12-dimethylbenz(a) anthracene (DMBA) induced oral carcinogenesis. Methods: Well differentiated squamous cell carcinoma was appeared in the buccal mucosa of hamsters painted with DMBA thrice a week for 14 weeks. The expression pattern of the molecular Original Research Article Manimaran et al.; BJMMR, 6(6): 587-596, 2015; Article no.BJMMR.2015.236 588 markers was analysed using immunohistochemistry (PCNA, VEGF), Real Time PCR (NFkB, cyclin D1) and ELISA (COX-2). Results: We noticed oral tumors in all the hamsters treated with DMBA alone and thus the tumor incidence is 100%. The total number of tumors developed in DMBA alone painted hamsters was 23. Upregulation of cell proliferative (PCNA, cyclin D1), inflammatory (NFkB, COX-2) and angiogenic markers (VEGF) was noticed in oral tumor bearing hamsters. Lupeol administration orally to DMBA painted hamsters completely inhibited the tumor formation (0%) and downregulated the immunoexpression pattern of cell proliferative (PCNA, cyclin D1), inflammatory (NFkB, COX-2) and angiogenic markers (VEGF). Conclusion: The present results suggest that lupeol exhibited antitumor potential through its anticell proliferative, anti-inflammatory and anti-angiogenic potential during DMBA induced oral carcinogenesis.