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Nephronophthisis (NPHP) is a ciliopathy characterized by renal fibrosis and cyst formation, and accounts for a significant portion of end stage renal disease in children and young adults. Currently, no targeted therapy is available for this disease. INVS/NPHP2 is one of the over 25 NPHP genes identified to date. In mouse, global knockout of Invs leads to renal fibrosis and cysts. However, the precise contribution of different cell types and the relationship between epithelial cysts and interstitial fibrosis remains undefined. Here, we generated and characterized cell-type-specific knockout mouse models of Invs, investigated the impact of removing cilia genetically on pheno-type severity in Invs mutants and evaluated the impact of the histone deacetylase inhibitor valproic acid (VPA) on Invs mutants. Epithelial-specific knockout of Invs in Invsflox/flox;Cdh16-Cre mutant mice resulted in renal cyst formation and severe stromal fibrosis, while Invsflox/flox;Foxd1 -Cre mice, where Invs is deleted in stromal cells, displayed no observable phenotypes up to the young adult stage, highlighting a significant role of epithelial-stromal crosstalk. Further, increased cell proliferation and myofibroblast activation occurred early during disease progression and preceded detectable cyst formation in the Invsflox/flox;Cdh16-Cre kidney. Moreover, concomitant removal of cilia partially suppressed the phenotypes of the Invsflox/flox;Cdh16-Cre mutant kidney, supporting a significant interaction of cilia and Invs function in vivo. Finally, VPA reduced cyst burden, decreased cell proliferation and ameliorated kidney function decline in Invs mutant mice. Our results reveal the critical role of renal epithelial cilia in NPHP and suggest the possibility of repurposing VPA for NPHP treatment. [ABSTRACT FROM AUTHOR]

In higher eukaryotes, mitochondria play multiple roles in energy production, signaling, and biosynthesis. Mitochondria possess multiple copies of mitochondrial DNA (mtDNA), which encodes 37 genes that are essential for mitochondrial and cellular function. When mtDNA is challenged by endogenous and exogenous factors, mtDNA undergoes repair, degradation, and compensatory synthesis. mtDNA degradation is an emerging pathway in mtDNA damage response and maintenance. A key factor involved is the human mitochondrial genome maintenance exonuclease 1 (MGME1). Despite previous biochemical and functional studies, controversies exist regarding the polarity of MGME1-mediated DNA cleavage. Also, how DNA sequence may affect the activities of MGME1 remains elusive. Such information is not only fundamental to the understanding of MGME1 but critical for deciphering the mechanism of mtDNA degradation. Herein, we use quantitative assays to examine the effects of substrate structure and sequence on the DNA-binding and enzymatic activities of MGME1. We demonstrate that MGME1 binds to and cleaves from the 50-end of single-stranded DNA substrates, especially in the presence of 50-phosphate, which plays an important role in DNA binding and optimal cleavage by MGME1. In addition, MGME1 tolerates certain modifications at the terminal end, such as a 50-deoxyribosephosphate intermediate formed in base excision repair. We show that MGME1 processes different sequences with varying efficiencies, with dT and dC sequences being the most and least efficiently digested, respectively. Our results provide insights into the enzymatic properties of MGME1 and a rationale for the coordination of MGME1 with the 3'-5' exonuclease activity of DNA polymerase γ in mtDNA degradation. [ABSTRACT FROM AUTHOR]

In higher eukaryotic cells, mitochondria are essential subcellular organelles for energy production, cell signaling, and the biosynthesis of biomolecules. The mitochondrial DNA (mtDNA) genome is indispensable for mitochondrial function because it encodes protein subunits of the electron transport chain and a full set of transfer and ribosomal RNAs. MtDNA degradation has emerged as an essential quality control measure to maintain mtDNA and to cope with mtDNA damage resulting from endogenous and environmental factors. Among all types of DNA damage known, abasic (AP) sites, sourced from base excision repair and spontaneous base loss, are the most abundant endogenous DNA lesions in cells. In mitochondria, AP sites trigger rapid DNA loss; however, the mechanism and molecular factors involved in the process remain elusive. Herein, we demonstrate that the stability of AP sites is reduced dramatically upon binding to a major mtDNA packaging protein, mitochondrial transcription factor A (TFAM). The half-life of AP lesions within TFAM- DNA complexes is 2 to 3 orders of magnitude shorter than that in free DNA, depending on their position. The TFAM-catalyzed AP-DNA destabilization occurs with nonspecific DNA or mitochondrial lightstrand promoter sequence, yielding DNA single-strand breaks and DNA-TFAM cross-links. TFAM-DNA cross-link intermediates prior to the strand scission were also observed upon treating AP-DNA with mitochondrial extracts of human cells. In situ trapping of the reaction intermediates (DNA-TFAM cross-links) revealed that the reaction proceeds via Schiff base chemistry facilitated by lysine residues. Collectively, our data suggest a novel role of TFAM in facilitating the turnover of abasic DNA. [ABSTRACT FROM AUTHOR]

Cilia are hair-like structures that function like antennae to detect chemical and mechanical signals in the environment. Recently, phosphoinositides were shown to play an important role in cilia assembly and disassembly. However, the precise molecular and cellular mechanisms underlying this process remain unknown. Here, we report that suppression of apical phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], by overexpressing apically targeted PtdIns(4,5)P2 phosphatase or by knocking down type I phosphatidylinositol 4-phosphate 5-kinase (Pip5k1), leads to ciliogenesis defects and polycystic kidney disease (PKD) in zebrafish embryos that phenocopied inpp5e mutant, a Joubert syndrome model. We further demonstrate that decreased expression of apical PtdIns(4,5)P2 disrupted apical ezrin recruitment, F-actin organization, and basal body docking. Moreover, the ciliogenesis and polycystic kidney defects in PtdIns(4,5)P2-depleted embryos can be rescued by overexpression of ezrin. Finally, Pip5k1a overexpression rescued the ciliogenesis defects and PKD phenotypes in Inpp5e-depleted embryos. Taken together, our results reveal that apical PtdIns(4,5)P2 is essential for ciliogenesis and the prevention of PKD and suggest a novel possibility for treating PKD and other human ciliopathies. [ABSTRACT FROM AUTHOR]

Overwhelming studies show that dysregulation of the Hippo pathway is positively correlated with cell proliferation, growth, and tumorigenesis. Paradoxically, the detailed molecular roles of the Hippo pathway in cell invasion remain debatable. Using a Drosophila invasion model in wing epithelium, we show herein that activated Hippo signaling promotes cell invasion and epithelialmesenchymal transition through JNK, as inhibition of JNK signaling dramatically blocked Hippo pathway activation-induced matrix metalloproteinase 1 expression and cell invasion. Furthermore, we identify bantam-Rox8 modules as essential components downstream of Yorkie in mediating JNK-dependent cell invasion. Finally, we confirm that YAP (Yes-associated protein) expression negatively regulates TIA1 (Rox8 ortholog) expression and cell invasion in human cancer cells. Together, these findings provide molecular insights into Hippo pathway-mediated cell invasion and also raise a noteworthy concern in therapeutic interventions of Hipporelated cancers, as simply inhibiting Yorkie or YAP activity might paradoxically accelerate cell invasion and metastasis. [ABSTRACT FROM AUTHOR]

DNA interstrand cross-links (ICLs) are cytotoxic DNA lesions derived from reactions of DNA with a number of anti-cancer reagents as well as endogenous bifunctional electrophiles. Deciphering the DNA repair mechanisms of ICLs is important for understanding the toxicity of DNA cross-linking agents and for developing effective chemotherapies. Previous research has focused on ICLs cross-linked with the N7 and N2 atoms of guanine as well as those formed at the N6 atom of adenine; however, little is known about the mutagenicity of O6-dG-derived ICLs. Although less abundant, O6-alkylated guanine DNA lesions are chemically stable and highly mutagenic. Here, O6-2'-deoxyguanosine-butylene-O6-2'-deoxyguanosine (O6-dG-C4-O6-dG) is designed as a chemically stable ICL, which can be induced by the action of bifunctional alkylating agents. We investigate the DNA replication-blocking and mutagenic properties of O6-dG-C4-O6-dG ICLs during an important step in ICL repair, translesion DNA synthesis (TLS). The model replicative DNA polymerase (pol) Sulfolobus solfataricus P2 DNA polymerase B1 (Dpo1) is able to incorporate a correct nucleotide opposite the cross-linked template guanine of ICLs with low efficiency and fidelity but cannot extend beyond the ICLs. Translesion synthesis by human pol κ is completely inhibited by O6-dG-C4-O6-dG ICLs. Moderate bypass activities are observed for human pol η and S. solfataricus P2 DNA polymerase IV (Dpo4). Among the pols tested, pol η exhibits the highest bypass activity; however, 70% of the bypass products are mutagenic containing substitutions or deletions. The increase in the size of unhooked repair intermediates elevates the frequency of deletion mutation. Lastly, the importance of pol η in O6-dG-derived ICL bypass is demonstrated using whole cell extracts of Xeroderma pigmentosum variant patient cells and those complemented with pol η. Together, this study provides the first set of biochemical evidence for the mutagenicity of O6-dG-derived ICLs. [ABSTRACT FROM AUTHOR]

5'-(2-Phosphoryl-1,4-dioxobutane) (DOB) is an oxidized abasic site that is produced by several antitumor agents and γ-radiolysis. DOB reacts reversibly with a dA opposite the 3'-adjacent nucleotide to form DNA interstrand cross-links (ICLs), genotoxic DNA lesions that can block DNA replication and transcription. Translesion synthesis (TLS) is an important step in several ICL repair pathways to bypass unhooked intermediates generated by endonucleolytic incision. The instability of DOB-ICLs has made it difficult to learn about their TLS-mediated repair capability and mutagenic potential. We recently developed a method for chemically synthesizing oligonucleotides containing a modified DOB-ICL analogue. Herein, we examined the capabilities of several highly relevant eukaryotic TLS DNA polymerases (pols), including human pol η, pol ?, pol ?, pol ν, REV1, and yeast pol ζ, to bypass this DOB-ICL analogue. The prelesion, translesion, and postlesion replication efficiency and fidelity were examined. Pol η showed moderate bypass activity when encountering the DOB-ICL, giving major products one or two nucleotides beyond the cross-linked template nucleotide. In contrast, DNA synthesis by the other pols was stalled at the position before the cross-linked nucleotide. Steady-state kinetic data and liquid chromatography-mass spectrometry sequencing of primer extension products by pol η unambiguously revealed that pol η-mediated bypass is highly error-prone. Together, our study provides the first set of in vitro evidence that the DOB-ICL is a replication-blocking and highly miscoding lesion. Compared to several other TLS pols examined, pol η is likely to contribute to the TLS-mediated repair of the DOB-ICL in vivo. [ABSTRACT FROM AUTHOR]

The (5'S)-8,5'-Cyclo-2'-deoxyguanosine (S-cdG) lesion is produced from reactions of DNA with hydroxyl radicals generated from ionizing radiation or endogenous oxidative metabolisms. An elevated level of S-cdG has been detected in Xeroderma pigmentosum, Cockayne syndrome, breast cancer patients, and aged mice. S-dG blocks DNA replication and transcription in vitro and in human cells and produces mutant replication and transcription products in vitro and in vivo. Major cellular protection against S-dG includes nucleotide excision repair and translesion DNA synthesis. We used kinetic and crystallographic approaches to elucidate the molecular mechanisms of S-cdG-induced DNA replication stalling using model B-family Sulfolobus solfataricus P2 DNA polymerase B1 (Dpol) and Y-family S. solfataricus P2 DNA polymerase IV (Dpo4). Dpol and Dpo4 inefficiently bypassed S-cdG with dCTP preferably incorporated and dTTP (for Dpo4) or dATP (for Dpol) misincorporated. Pre-steady-state kinetics and crystallographic data mechanistically explained the low-efficiency bypass. For Dpol, S-cdG attenuated KdtdNTP,app and kpol. For Dpo4, the S-cdG-adducted duplex caused a 6-fold decrease in Dpo4:DNA binding affinity and significantly reduced the concentration of the productive Dpo4: DNA:dCTP complex. Consistent with the inefficient bypass, crystal structures of Dpo4:DNA(S-cdG): dCTP (error-free) and Dpo4:DNA(ScdG): dTTP (error-prone) complexes were catalytically incompetent. In the Dpo4:DNA(S-cdG):dTTP structure, S-cdG induced a loop structure and caused an unusual 5'-template base clustering at the active site, providing the first structural evidence of the previously suggested template loop structure that can be induced by a cyclopurine lesion. Together, our results provided mechanistic insights into S-cdG-induced DNA replication stalling. [ABSTRACT FROM AUTHOR]

Purpose: Although laparoscopic pancreaticoduodenectomy (LPD) is increasingly performed in high-volume centers, pancreaticojejunostomy (PJ) is still the most challenging procedure. Pancreatic anastomotic leakage remains a major complication after PD. Thus, various technical modifications regarding PJ, such as the Blumgart technique, have been attempted to simplify the procedure and minimize anastomotic leakage. Three-dimensional (3D) laparoscopic systems have been shown to be particularly helpful in performing difficult and precise tasks. We present a modified Blumgart anastomosis in 3D-LPD and investigate its clinical outcomes. Methods: A retrospective analysis of 100 patients who underwent 3D-LPD with modified Blumgart PJ from September 2018 to January 2020 was conducted. Data on the preoperative characteristics, operative outcomes, and postoperative characteristics of the patients were collected and analyzed. Results: The mean operative time and duration of PJ were 348.2 and 25.1 min, respectively. The mean estimated blood loss was 112 mL. The overall rate of postoperative complications over Clavien‒Dindo classification III was 18%. The incidence of clinically relevant postoperative pancreatic fistula was 11%. The median postoperative hospital stay was 14.2 days. Only one patient required reoperation (1%), and no patient died in the hospital or 90 days after the operation. High BMI, small main pancreatic duct diameter, and soft pancreatic consistency had a significant influence on the occurrence of CR-POPF. Conclusions: The surgical outcome of 3D-LPD with modified Blumgart PJ seems to be comparable to other studies in terms of operation time, blood loss, hospital stay, and complication incidence. We consider the modified Blumgart technique in 3D-LPD to be novel, reliable, safe, and favorable for PJ in the PD procedure. [ABSTRACT FROM AUTHOR]

Infectious hypodermal and hematopoietic necrosis virus (IHHNV) is a harmful virus that is responsible for the remarkable economic loss of Litopenaeus vannamei culture. IHHNV was first observed in shrimps, which were characterized by light microscopy, SEM, and TEM. The infected shrimps showed severe morphological deformity, including reduced body size, bent rostrum, shrunken and twisted antenna, rough cuticles, shrunken eyes, and rigid muscles. The antennal segments of the infected shrimps were fused together, puffy, dented, bent, and rough, as observed under a scanning electron microscope. The affected shrimps also showed tumor-like growth (hyperplasia) at the lateral position of the carapace in which the gastrofrontal sulcus was bent. This hyperplasia was found to be soft. In addition, the connective tissue of the diseased shrimp was in a degraded state, and the muscle fibers were despoiled. The nucleus of the cells from the infected gill cells of the shrimps was almost occupied by viral icosahedral particles, which TEM revealed. These viral particles were also found in the cytoplasm in a scattered manner within the same cells and were identified as IHHNV, as confirmed by polymerase chain reaction. [ABSTRACT FROM AUTHOR]

The Hippo and c-Jun N-terminal kinase (JNK) pathway both regulate growth and contribute to tumorigenesis when dysregulated. Whereas the Hippo pathway acts via the transcription coactivator Yki/YAP to regulate target gene expression, JNK signaling, triggered by various modulators including Rho GTPases, activates the transcription factors Jun and Fos. Here, we show that impaired Hippo signaling induces JNK activation through Rho1. Blocking Rho1-JNK signaling suppresses Yki-induced overgrowth in the wing disk, whereas ectopic Rho1 expression promotes tissue growth when apoptosis is prohibited. Furthermore, Yki directly regulates Rho1 transcription via the transcription factor Sd. Thus, our results have identified a novel molecular link between the Hippo and JNK pathways and implicated the essential role of the JNK pathway in Hippo signaling-related tumorigenesis. [ABSTRACT FROM AUTHOR]

DNA damage impinges on genetic information flow and has significant implications in human disease and aging. Lucidin-3-O-primeveroside (LuP) is an anthraquinone derivative present in madder root, which has been used as a coloring agent and food additive. LuP can be metabolically converted to genotoxic compound lucidin, which subsequently forms lucidin-specific N²-2'-deoxyguanosine (N²-dG) and N6-2'-deoxyadenosine (N6-dA) DNA adducts. Lucidin is mutagenic and carcinogenic in rodents but has low carcinogenic risks in humans. To understand the molecular mechanism of low carcinogenicity of lucidin in humans, we performed DNA replication assays using site-specifically modified oligodeoxynucleotides containing a structural analogue (LdG) of lucidin-N²-dG DNA adduct and determined the crystal structures of DNA polymerase (pol) κ in complex with LdG-bearing DNA and an incoming nucleotide. We examined four human pols (pol η, pol ι, pol κ, and Rev1) in their efficiency and accuracy during DNA replication with LdG; these pols are key players in translesion DNA synthesis. Our results demonstrate that pol κ efficiently and accurately replicates past the LdG adduct, whereas DNA replication by pol η, pol ι is compromised to different extents. Rev1 retains its ability to incorporate dCTP opposite the lesion albeit with decreased efficiency. Two ternary crystal structures of pol κ illustrate that the LdG adduct is accommodated by pol κ at the enzyme active site during insertion and postlesion-extension steps. The unique open active site of pol κ allows the adducted DNA to adopt a standard B-form for accurate DNA replication. Collectively, these biochemical and structural data provide mechanistic insights into the low carcinogenic risk of lucidin in humans. [ABSTRACT FROM AUTHOR]

Background: Carcinoembryonic antigen (CEA) is one of the most widely used tumor markers and is increased in 30%-60% of patients with pancreatic cancer. Although carbohydrate antigen 19-9 (CA19-9) is the most important serum biomarker in pancreatic cancer, the diagnostic and prognostic value of CEA is gradually being recognized. Materials and methods: The MEDLINE, EMBASE, and Web of Science databases were searched for related literature published until January 2017. Diagnostic accuracy variables were pooled using the Meta-Disc software. The pooled hazard ratios (HRs) for prognostic data were calculated and analyzed using Stata software. Results: A total of 3,650 participants enrolled in 19 studies met our inclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of a CEA-based panel were 0.45 (95% confidence interval [CI], 0.41-0.50), 0.89 (95% CI, 0.86-0.91), 5.39 (95% CI, 3.16-9.18), and 0.55 (95% CI, 0.41-0.72), respectively. The area under the curve (AUC, 0.90) and Q-value (0.84) of the CEA-based panel indicated a significantly higher diagnostic accuracy compared with CEA or CA19-9 alone. Moreover, there was also a significant association between high levels of CEA and worse overall survival (HR, 1.43; 95% CI, 1.31-1.56). Conclusion: Our meta-analysis indicated that elevated serum CEA level, as a vital supplementary to CA19-9, can play an important role in the clinical diagnosis of pancreatic cancer patients and predict poor prognosis. [ABSTRACT FROM AUTHOR]

Silicon-based two-dimensional (2D) materials are uniquely suited for integration in Si-based electronics. Silicene, an analogue of graphene, was recently fabricated on several substrates and was used to make a field-effect transistor. Here, we report that when Ru(0001) is used as a substrate, a range of distinct monolayer silicon structures forms, evolving toward silicene with increasing Si coverage. Low Si coverage produces a herringbone structure, a hitherto undiscovered 2D phase of silicon. With increasing Si coverage, herringbone elbows evolve into silicene-like honeycomb stripes under tension, resulting in a herringbone-honeycomb 2D superlattice. At even higher coverage, the honeycomb stripes widen and merge coherently to form silicene in registry with the substrate. Scanning tunneling microscopy (STM) was used to image the structures. The structural stability and electronic properties of the Si 2D structures, the interaction between the Si 2D structures and the Ru substrate, and the evolution of the distinct monolayer Si structures were elucidated by density functional theory (DFT) calculations. This work paves the way for further investigations of monolayer Si structures, the corresponding growth mechanisms, and possible functionalization by impurities. [ABSTRACT FROM AUTHOR]

Pancreatic cancer is a human malignancy with one of the highest mortality rates and little progress has been achieved in its treatment in recent decades. Further improvement to the understanding of the biological and molecular mechanisms underlying the initiation and development of pancreatic ductal adenocarcinoma (PDAC) is required. Previous studies using genetically engineered mouse models have demonstrated that oncogenic GTPase KRas (KRAS) mutation is involved in the formation of pancreatic intraepithelial neoplasia and promotes the progression of PDAC. However, attempts to target KRAS directly by pharmacological inhibition have been unsuccessful. This has resulted in increased efforts to identify pharmacological targets and nodes associated with the mutated KRAS. The present review discusses the recent progress and prospects of KRAS signaling in pancreatic cancer. [ABSTRACT FROM AUTHOR]

The intercalation of heteroatoms between graphene and a metal substrate has been studied intensively over the past few years, due to its effect on the graphene properties, and as a method to create vertical heterostructures. Various intercalation processes have been reported with different combinations of heteroatoms and substrates. Here we study Si intercalation between graphene and Ru(0001). We elucidate the role of cooperative interactions between heteroatoms, graphene, and substrate. By combining scanning tunneling microscopy with density functional theory, the intercalation process is confirmed to consist of four key steps, involving creation of defects, migration of heteroatoms, self-repairing of graphene, and growth of an intercalated monolayer. Both theory and experiments indicate that this mechanism applies also to other combinations of hetero-atoms and substrates. [ABSTRACT FROM AUTHOR]

We review the way to fabricate large-scale, high-quality and single crystalline graphene epitaxially grown on Ru(0001) substrate. A moiré pattern of the graphene/Ru(0001) is formed due to the lattice mismatch between graphene and Ru(0001). This superstructure gives rise to surface charge redistribution and could behave as an ordered quantum dot array, which results in a perfect template to guide the assembly of organic molecular structures. Molecules, for example iron phthalocyanine and C60, on this template show how the molecule-substrate interaction makes different superstructures. These results show the possibility of constructing ordered molecular structures on graphene/Ru(0001), which is helpful for practical applications in the future. [ABSTRACT FROM AUTHOR]

Background: Tumor cells exhibit abnormal actin remodeling profiles, which involve the altered expressions of several important actin-binding proteins. Profilin1 (Pfn1), originally identified as an actin-associated protein, has been linked to several human malignancies. Our recent studies suggested that Pfn1 facilitates apoptosis in pancreatic cancer cells. Here, we investigated the exact role of Profilin1 (Pfn1) in pancreatic adenocarcinoma (PDAC) and the underlying mechanisms. Methods: Pfn1 protein expression in PDAC specimens was analyzed by immunohistochemistry using a tissue microarray (TMA) containing PDAC tumor tissue and corresponding normal tissue samples from 72 patients. The effect of Pfn1 expression on cancer proliferation was assessed in cells by up- and down-regulation of Pfn1 in vitro and in vivo. Immunoprecipitation and mass spectrometry were used to identify the Pfn1-associated proteins and potential pathways. Results: Pfn1 was downregulated in clinical pancreatic adenocarcinoma specimens compared with the surrounding benign tissues. Univariate survival analysis of the PDAC cohorts showed that low expression of Pfn1 was significantly correlated with shortened patient survival (mean 14.2 months versus 20.9 months, P < 0.05). Restoration of Pfn1 in pancreatic cancer cells with low endogenous Pfn1 expression resulted in a nontumorigenic phenotype, suggesting that Pfn1 may be a negative regulator of pancreatic cancer progression. Overexpression of Pfn1 in vivo decreased the tumor volume in orthotopic xenograft nude mice models. Pfn1 upregulated the expression of SIRT3, leading to HIF1α destabilization. This data revealed that aberrant Pfn1 expression contributes to pancreatic cancer progression. Conclusions: Our data suggest that Pfn1 is a tumor suppressor in pancreatic cancer that acts via a novel mechanism of regulating the SIRT3-HIF1α axis, independently of its cytoskeleton-related activity. [ABSTRACT FROM AUTHOR]

Many Violaceae plants contain cyclotides, which are plant cyclopeptides distinguished by a cyclic cystine knot motif with 28-37 amino acid residues. In the current study, four new cyclotides, vila A-D (-, resp.), together with a known cyclotide, varv D (), were isolated from Viola labridorica (Violaceae). A chromatography-based method was used to isolate the cyclotides, which were characterized using tandem mass spectrometry and 2D-NMR spectroscopy. Several of the cyclotides showed cytotoxic activities against five cancer cell lines, i.e., U251, MDA-MB-231, A549, DU145, and BEL-7402, with vila A and B ( and , resp.) being the most cytotoxic. The isolated cyclotides showed no antibacterial activity against Staphyloccocus aureus and Candida albicans. Homology modeling of the cyclotide structures was used to analyze structure-activity relationships. [ABSTRACT FROM AUTHOR]

Background: Methyl-CpG binding domain protein 1 (MBD1), which couples DNA methylation to transcriptional repression, has been implicated in transcriptional regulation, heterochromatin formation, genomic stability, cell cycle progression and development. It has also been proven that MBD1 is involved in tumor development and progression. However, whether MBD1 is involved in tumorigenesis, especially in gallbladder cancer, is totally unknown. Methods: Human GBC-SD and SGC996 cells were used to perform experiments. Invasion, wound healing and colony formation assays were performed to evaluate cell viability. A CCK-8 assay was performed to assess gallbladder cancer cell viability after gemcitabine treatment. Western blot analysis was used to evaluate changes in protein expression. Human gallbladder cancer tissues and adjacent nontumor tissues were subjected to immunohistochemical staining to detect protein expression. Results: We found that MBD1 expression was significantly upregulated in gallbladder cancer tissues compared with that in surrounding normal tissues according to immunohistochemical analysis of 84 surgically resected gallbladder cancer specimens. These data also indicated that higher MBD1 expression was correlated with lymph node metastasis and poor survival in gallbladder cancer patients. Overexpression and deletion in vitro validated MBD1 as a potent oncogene promoting malignant behaviors in gallbladder cancer cells, including invasion, proliferation and migration, as well as epithelial–mesenchymal transition. Studies have demonstrated that epithelial–mesenchymal transition is common in gallbladder cancer, and it is well known that drug resistance and epithelial–mesenchymal transition are very closely correlated. Herein, our data show that targeting MBD1 restored gallbladder cancer cell sensitivity to gemcitabine chemotherapy. Conclusions: Taken together, the results of our study revealed a novel function of MBD1 in gallbladder cancer tumor development and progression through participation in the gallbladder cancer epithelial–mesenchymal transition program, which is involved in resistance to gemcitabine chemotherapy. Thus, MBD1 may be a potential therapeutic target for gallbladder cancer. [ABSTRACT FROM AUTHOR]