Olympic gels formed through catenation of dsDNA rings regulated by topoisomerase II: A coarse-grained model.

Topological regulation of DNA by topoisomerases in cells is very crucial for life. We propose a coarse-grained model to study the catenation process of double-stranded DNA (dsDNA) rings regulated by topoisomerase II (TOP2) and provide a computational method to characterize the topological structures of the Olympic gels obtained. The function of TOP2 in the catenation of dsDNA rings is implicitly fulfilled by operating the length of a stretchable catch bond in the dsDNA ring. After the catenation reaction of initially noncatenated dsDNA rings in the solution, the Olympic gel is obtained and the interlocked topology of the dsDNA rings can be characterized by a computational method derived from the HOMFLY polynomial, based on which the catenation degree and the complexity of catenation are quantified. Detailed dependence of the catenation degree and the complexity of the catenated topology on key parameters, including the size of the transient broken gap and the duration time of the break on the dsDNA ring during operation by TOP2, the initial molar ratio of TOP2 to the dsDNA rings, and the reaction temperature, has been investigated.

Usage of a simplified blumgart pancreaticojejunostomy in laparoscopic pancreaticoduodenectomy: a single center experience.

BACKGROUND: Blumgart pancreaticojejunostomy (PJ) was shown to be an effective method for pancreaticojejunostomy in open pancreaticoduodenectomy. But the original Blumgart method is involved in complicated and interrupted sutures, which may not be suitable for the laparoscopic approach. In this study, we introduced a simplified Blumgart method for laparoscopic pancreaticojejunostomy. METHODS: We retrospectively reviewed 90 cases of pancreaticoduodenectomy in our institute from 2019 to 2022. Among them, 32 patients received LPD with simplified Blumgart PJ, while 29 received LPD with traditional duct-to-mucosal anastomosis (the Cattel-Warren technique) and 29 received OPD with traditional duct-to-mucosal anastomosis. And the time length for PJ and the surgical outcome were compared in these three groups. RESULTS: The simplified Blumgart pancreaticojejunostomy was accomplished in all 32 cases with no conversion to open surgery due to improper sutures. And the time length for laparoscopic simplified Blumgart pancreaticojejunostomy was 26 ± 8.4 min, which was shorter than laparoscopic traditional ductal to mucosa pancreaticojejunostomy (39 ± 13.7 min). Importantly, the overall incidence for POPF and grade B&C POPF rate in the laparoscopic simplified Blumgart method group were 25% and 9.38% respectively, which were lower than the other two groups. Moreover, we performed univariate analysis and multivariate analysis and found soft pancreas, pancreatic ductal diameter < = 3 mm and intraoperative blood loss were independent risk factors for POPF after PD. CONCLUSION: Our data suggest that the simplified Blumgart method is a feasible and reliable method for laparoscopic PJ which deserves further validation.

A single QTL harboring multiple genetic variations leads to complicated phenotypic segregation in apple flesh firmness and crispness.

KEY MESSAGE: Within a QTL, the genetic recombination and interactions among five and two functional variations at MdbHLH25 and MdWDR5A caused much complicated phenotype segregation in apple FFR and FCR. The storability of climacteric fruit like apple is a quantitative trait. We previously identified 62 quantitative trait loci (QTLs) associating flesh firmness retainability (FFR) and flesh crispness retainability (FCR), but only a few functional genetic variations were identified and validated. The genetic variation network controlling fruit storability is far to be understood and diagnostic markers are needed for molecular breeding. We previously identified overlapped QTLs F16.1/H16.2 for FFR and FCR using an F1 population derived from 'Zisai Pearl' × 'Red Fuji'. In this study, five and two single-nucleotide polymorphisms (SNPs) were identified on the candidate genes MdbHLH25 and MdWDR5A within the QTL region. The SNP1 A allele at MdbHLH25 promoter reduced the expression and SNP2 T allele and/or SNP4/5 GT alleles at the exons attenuated the function of MdbHLH25 by downregulating the expression of the target genes MdACS1, which in turn led to a reduction in ethylene production and maintenance of higher flesh crispness. The SNPs did not alter the protein-protein interaction between MdbHLH25 and MdWDR5A. The joint effect of SNP genotype combinations by the SNPs on MdbHLH25 (SNP1, SNP2, and SNP4) and MdWDR5A (SNPi and SNPii) led to a much broad spectrum of phenotypic segregation in FFR and FCR. Together, the dissection of these genetic variations contributes to understanding the complicated effects of a QTL and provides good potential for marker development in molecular breeding.

In Vitro Response of Immune Cells on Metal Oxide Nanoparticles with Different Solubility.

In this study, three engineered metal oxide nanoparticles (NPs) with similar size but significantly different solubility were used to study the cellular uptake, toxicity and immune activation of Raw 264.7 cells. Commercially available TiO2, Fe2O3 and ZnO NPs were used in this study. Although the size of three pristine NPs are different, all three NPs showed similar aggregation state (250-300 nm) and surface zeta potential (-10 mV) in serum containing cell culture medium due to the surface adsorption of proteins. The ZnO NPs release high concentration of Zn2+ in cell culture medium, especially at lower pH mimicking endosomal environment. In contrast, Fe2O3 NPs have limited solubility and TiO2 NPs only release very low concentration of ions. The cellular loading of the TiO2 and Fe2O3 NPs increased with the incubation time and Raw264.7 cells ingested more Fe2O3 NPs than TiO2 NPs. In general, the TiO2 and Fe2O3 NPs did not have obvious cytotoxicity. However, the TiO2 and Fe2O3 NPs can induce strong immune response of Raw264.7 cells, leading to higher expression of TNF-α and IL-6, especially at relatively longer incubation time. ZnO NPs were rapidly ingested into cells and release Zn2+, inducing significant cell death. They also can enhance the expression of TNF-a and IL-6 of Raw264.7 cells at beginning, but reduced significantly at longer incubation time due to cell death.

Advances in Engineering Circular RNA Vaccines.

Engineered circular RNAs (circRNAs) are a class of single-stranded RNAs with head-to-tail covalently linked structures that integrate open reading frames (ORFs) and internal ribosome entry sites (IRESs) with the function of coding and expressing proteins. Compared to mRNA vaccines, circRNA vaccines offer a more improved method that is safe, stable, and simple to manufacture. With the rapid revelation of the biological functions of circRNA and the success of Severe Acute Respiratory Coronavirus Type II (SARS-CoV-2) mRNA vaccines, biopharmaceutical companies and researchers around the globe are attempting to develop more stable circRNA vaccines for illness prevention and treatment. Nevertheless, research on circRNA vaccines is still in its infancy, and more work and assessment are needed for their synthesis, delivery, and use. In this review, based on the current understanding of the molecular biological properties and immunotherapeutic mechanisms of circRNA, we summarize the current preparation methods of circRNA vaccines, including design, synthesis, purification, and identification. We discuss their delivery strategies and summarize the challenges facing the clinical application of circRNAs to provide references for circRNA vaccine-related research.

Prognostic significance of glucose-lipid metabolic index in pancreatic cancer patients with diabetes mellitus.

BACKGROUND: The incidence of pancreatic cancer (PC) is higher in diabetic patients due to disturbances in glucose and lipid metabolism caused by insulin resistance (IR). However, the effect of diabetes as well as IR on the prognosis of PC patients remains inconclusive. Our study aims to assess the impact of IR on the prognosis of PC patients with diabetes. METHODS: We conducted a retrospective analysis of 172 PC patients with diabetes in our institute from 2015 to 2021. Prognostic assessment was performed using univariate/multifactorial analysis and survival analysis. The predictive efficacy of metabolic indices was compared using receiver operator characteristic (ROC) curve analysis. RESULTS: One hundred twenty-one of 172 patients died during follow-up, with a median follow-up of 477 days and a median overall survival (OS) of 270 days. Survival analysis showed a significant difference in OS by IR related parameters, which were triglyceride-glucose index (TyG), triglyceride-glucose index-body mass index (TyG-BMI), and triglyceride/high-density lipoprotein cholesterol ratio (TG/HDL-c). The ROC curve indicated that TyG, TyG-BMI, and TG/HDL-c had prognostic efficacy for PC with diabetes. We next optimized TyG-BMI and obtained a new parameter, namely glucose-lipid metabolism index (GLMI), and the patients were classified into GLMI low group and high group based on the calculated cutoff value. The GLMI high group had higher TyG, TyG-BMI, TyG/HDL-c, BMI, TG, total cholesterol (TC), TC/HDL-c, fasting plasma glucose, CA199, and more advanced tumor stage compared to low group. Univariate and multivariate analyses showed that GLMI was an independent prognostic factor. Furthermore, the patients of GLMI high group had worse OS compared to low group and the ROC curves showed GLMI had better predictive ability than TyG and TyG-BMI. CONCLUSIONS: IR is associated with the outcome of PC patients with diabetes and higher level of IR indicates worse prognosis. GLMI has a good predictive value for PC with diabetes.

Identification and validation of stemness-based and ferroptosis-related molecular clusters in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with an extremely poor prognosis. Cancer stem cells (CSCs) are considered to be responsible for the poor survival, recurrence and therapy resistance of PDAC. Ferroptosis plays a crucial role in the sustain and survival of CSCs. Here, we employed a rigorous evaluation of multiple datasets to identify a novel stemness-based and ferroptosis-related genes (SFRGs) signature to access the potential prognostic application. This work we retrieved RNA-sequencing and clinical annotation data from the TCGA, ICGC, GTEx and GEO database, and acquired 26 stem cell gene sets and 259 ferroptosis genes from StemChecker database and FerrDb database, respectively. Based on consensus clustering and ssGSEA analysis, we identified two expression patterns of CSCs traits (C1 and C2). Then, WGCNA analysis was implemented to screen out hub module genes correlated with stemness. Furthermore, differential expression analysis, Pearson correlation analysis, and the Least absolute shrinkage and selection operator (LASSO) and Cox regression were performed to identify the SFRGs and to construct model. In addition, the differences in prognosis, tumor microenvironment (TME) components and therapy responses were evaluated between two risk groups. Finally, we verified the most influential marker ARNTL2 experimentally by western blot, qRT-PCR, sphere formation assay, mitoscreen assay, intracellular iron concentration determination and MDA determination assays. In conclusion, we developed a stemness-based and ferroptosis-related prognostic model, which could help predict overall survival for PDAC patients. Targeting ferroptosis may be a promising therapeutic strategy to inhibit PDAC progression by suppressing CSCs.

Parasitic nematode-induced modulation of body weight and associated metabolic dysfunction in mouse models of obesity.

Obesity is associated with a chronic low-grade inflammation characterized by increased levels of proinflammatory cytokines that are implicated in disrupted metabolic homeostasis. Parasitic nematode infection induces a polarized Th2 cytokine response and has been explored to treat autoimmune diseases. We investigated the effects of nematode infection against obesity and the associated metabolic dysfunction. Infection of RIP2-Opa1KO mice or C57BL/6 mice fed a high-fat diet (HFD) with Nippostrongylus brasiliensis decreased weight gain and was associated with improved glucose metabolism. Infection of obese mice fed the HFD reduced body weight and adipose tissue mass, ameliorated hepatic steatosis associated with a decreased expression of key lipogenic enzymes/mediators, and improved glucose metabolism, accompanied by changes in the profile of metabolic hormones. The infection resulted in a phenotypic change in adipose tissue macrophages that was characterized by upregulation of alternative activation markers. Interleukin-13 (IL-13) activation of the STAT6 signaling pathway was required for the infection-induced attenuation of steatosis but not for improved glucose metabolism, whereas weight loss was attributed to both IL-13/STAT6-dependent and -independent mechanisms. Parasitic nematode infection has both preventive and therapeutic effects against the development of obesity and associated features of metabolic dysfunction in mice.

Surgical treatment of primary hepatic neuroendocrine tumor diagnosed by Al18F-NOTA-Octreotide PET/CT: a case report.

Neuroendocrine tumors (NETs) are a heterogeneous group of tumors originating from peptide-producing neurons and neuroendocrine cells. The liver is the most common site of metastasis for NETs, while primary hepatic neuroendocrine tumors (PHNETs) are exceedingly rare. While somatostatin receptor scintigraphy (SRS) has demonstrated superior efficacy compared to [18F]FDG PET imaging in the diagnosis of neuroendocrine tumors, [18F]AlF-NOTA-Octreotide ([18F]AlF-OC) PET/CT also exhibits specific advantages over SRS. This article presents a case study of a patient with a liver mass who underwent sequential [18F]FDG and [18F]AlF-OC PET/CT scans, ruling out hepatocellular carcinoma and confirming the diagnosis of PHNETs. Subsequently, the patient underwent surgical treatment. From another perspective, [18F]AlF-OC exhibits distinct advantages. The postoperative pathology revealed a PHNETs, which further emphasizes its clinical rarity.

A case report of surgical resection treatment for complete remission after chemotherapy for advanced pancreatic cancer.

Pancreatic cancer is a common type of cancer that is treated using surgery or chemotherapy. However, for patients who cannot have surgery, the treatment options are limited and have a low success rate. We report a case of a patient with locally advanced pancreatic cancer who was unable to have surgery due to a tumor that had invaded the coeliac axis and portal vein. However, after receiving chemotherapy with gemcitabine plus nab-paclitaxel(GEM-NabP), the patient achieved complete remission, and a PET-CT scan confirmed that the tumor had disappeared. Eventually, the patient underwent radical surgery with distal pancreatectomy with splenectomy, and the treatment was successful. This case is rare, and there are few reports of complete remission after chemotherapy for pancreatic cancer. This article reviews the relevant literature and guides future clinical practice.

Case Report: Camrelizumab combined with gemcitabine and oxaliplatin in the treatment of advanced intrahepatic cholangiocarcinoma: a case report and literature review.

Intrahepatic cholangiocarcinoma (ICC) is one of the most common invasive malignant tumors, with a 5-year survival rate of less than 5%. Currently, radical surgical resection is the preferred treatment for ICC. However, most patients are only diagnosed at an advanced stage and are therefore not eligible for surgery. Herein, we present a case of advanced ICC in which radical surgery was not possible due to tumor invasion of the second porta hepatis and right hepatic artery. Six treatment cycles with a gemcitabine and oxaliplatin (GEMOX) regimen combined with camrelizumab immunotherapy achieved a partial response and successful tumor conversion, as tumor invasion of the second porta hepatis and right hepatic artery was no longer evident. The patient subsequently underwent successful radical surgical resection, including hepatectomy, caudate lobe resection, and cholecystectomy combined with lymph node dissection. Cases of patients with advanced ICC undergoing surgical resection after combined immunotherapy and chemotherapy are rare. The GEMOX regimen combined with camrelizumab demonstrated favorable antitumor efficacy and safety, suggesting that it might be a potential feasible and safe conversion therapy strategy for patients with advanced ICC.

Dataset-Driven Unsupervised Object Discovery for Region-Based Instance Image Retrieval.

Instance image retrieval could greatly benefit from discovering objects in the image dataset. This not only helps produce more reliable feature representation but also better informs users by delineating query-matched object regions. However, object classes are usually not predefined in a retrieval dataset and class label information is generally unavailable in image retrieval. This situation makes object discovery a challenging task. To address this, we propose a novel dataset-driven unsupervised object discovery framework. By utilizing deep feature representation and weakly-supervised object detection, we explore supervisory information from within an image dataset, construct class-wise object detectors, and assign multiple detectors to each image for detection. To efficiently construct object detectors for large image datasets, we propose a novel "base-detector repository" and derive a fast way to generate the base detectors. In addition, the whole framework is designed to work in a self-boosting manner to iteratively refine object discovery. Compared with existing unsupervised object detection methods, our framework produces more accurate object discovery results. Different from supervised detection, we need neither manual annotation nor auxiliary datasets to train object detectors. Experimental study demonstrates the effectiveness of the proposed framework and the improved performance for region-based instance image retrieval.

Preparation and Properties of Poly(butylene adipate-co-terephthalate)/thermoplastic Hydroxypropyl Starch Composite Films Reinforced with Nano-Silica.

The use of biodegradable plastics is gradually increasing, but its expensive cost limits promotion. In this study, poly(butylene adipate-co-terephthalate)/thermoplastic hydroxypropyl starch reinforced with nano-silica (PBAT/TPHSg-SiO2) composite films with high hydroxypropyl starch content were prepared in a two-step process. The effect of reinforced thermoplastic hydroxypropyl starch on the mechanical, thermal, processing properties, and micromorphology of the composite films was investigated. The results showed that the tensile strength of the composite films was significantly improved by the addition of nano-silica, with 35% increase in horizontal tensile strength and 21% increase in vertical tensile strength after the addition of 4 phr of nano-silica. When the content of thermoplastic hydroxypropyl starch reinforced with nano-silica (TPHSg-4SiO2) is 40%, the horizontal and vertical tensile strengths of the films are 9.82 and 12.09 MPa, respectively, and the elongation at break of the films is over 500%. Electron micrographs show that TPHSg-4SiO2 is better homogeneously dispersed in the PBAT and exhibits a bi-continuous phase structure at a TPHSg-4SiO2 content of 40%. In this study, the blowing PBAT/TPHSg-4SiO2 composite films effectively reduce the cost and still show better mechanical properties, which are suitable for packaging applications.

Polymer-Based Long-Lived Phosphorescence Materials over a Broad Temperature Based on Coumarin Derivatives as Information Anti-Counterfeiting.

The development of new polymer-based room-temperature phosphorescence materials is of great significance. By a special molecule design and a set of feasible property-enhancing strategies, coumarin derivatives (CMDs, Ma-Mf) were doped into polyvinyl alcohol (PVA), polyacrylamide (PAM), corn starch, and polyacrylonitrile (PAN) as information anti-counterfeiting. CMDs-doped PVA and CMDs-doped corn starch films showed long-lived phosphorescence emissions up to 1246 ms (Ma-PVA) and 697 ms (Ma-corn starch), reaching over 10 s afterglow under naked eye observation under ambient conditions. Significantly, CMDs-doped PAM films can display long-lived phosphorescence emissions in a wide temperature range (100-430 K). For example, the Me-PAM film has a phosphorescence lifetime of 16 ms at 430 K. The use of PAM with the strong polarity and rigidity has expanded the temperature range of long-life polymer-based phosphorescent materials. The present long-lived phosphorescent systems provide the possibility for developing new polymer-based organic afterglow materials with robust phosphorescence.

Regulation of iron metabolism and ferroptosis in cancer stem cells.

The ability of cancer stem cells (CSCs) to self-renew, differentiate, and generate new tumors is a significant contributor to drug resistance, relapse, and metastasis. Therefore, the targeting of CSCs for treatment is particularly important. Recent studies have demonstrated that CSCs are more susceptible to ferroptosis than non-CSCs, indicating that this could be an effective strategy for treating tumors. Ferroptosis is a type of programmed cell death that results from the accumulation of lipid peroxides caused by intracellular iron-mediated processes. CSCs exhibit different molecular characteristics related to iron and lipid metabolism. This study reviews the alterations in iron metabolism, lipid peroxidation, and lipid peroxide scavenging in CSCs, their impact on ferroptosis, and the regulatory mechanisms underlying iron metabolism and ferroptosis. Potential treatment strategies and novel compounds targeting CSC by inducing ferroptosis are also discussed.

Genome-wide CRISPR/Cas9 screening for drug resistance in tumors.

Genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated nuclease 9 (Cas9) screening is a simple screening method for locating loci under specific conditions, and it has been utilized in tumor drug resistance research for finding potential drug resistance-associated genes. This screening strategy has significant implications for further treatment of malignancies with acquired drug resistance. In recent years, studies involving genome-wide CRISPR/Cas9 screening have gradually increased. Here we review the recent application of genome-wide CRISPR/Cas9 screening for drug resistance, involving mitogen-activated protein kinase (MAPK) pathway inhibitors, poly (ADP-ribose) polymerase inhibitors (PARPi), alkylating agents, mitotic inhibitors, antimetabolites, immune checkpoint inhibitors (ICIs), and cyclin-dependent kinase inhibitors (CDKI). We summarize drug resistance pathways such as the KEAP1/Nrf2 pathway MAPK pathway, and NF-κB pathway. Also, we analyze the limitations and conditions for the application of genome-wide CRISPR/Cas9 screening techniques.

High Expression of COL10A1 Is an Independent Predictive Poor Prognostic Biomarker and Associated with Immune Infiltration in Advanced Gastric Cancer Microenvironment.

Medical technology has become more and more sophisticated recently, which, however, fails to contribute to a better prognosis for patients suffering advanced gastric cancer (GC). Hence, new biomarkers specific to GC diagnosis and prognosis shall be identified urgently. This study screened differentially expressed genes (DEGs) between 375 GC samples and 32 paracancer tissue samples from TCGA datasets. The expression of Collagen type X alpha 1 (COL10A1) in GC was analyzed. The chi-square test assisted in analyzing the relevance of COL10A1 to the clinicopathologic characteristics. The Kaplan-Meier method helped to assess the survival curves and log-rank tests assisted in the examination of the differences. The Cox proportional hazard regression model served for analyzing the risk factors for GC. Then, we developed a nomogram that contained the COL10A1 expression and clinical information. Finally, how COL10A1 expression was associated with the immune infiltration was also evaluated. In this study, 7179 upregulated and 3771 downregulated genes were identified. Among them, COL10A1 expression was distinctly increased in GC specimens compared with nontumor specimens. High COL10A1 expression exhibited an obvious relation to tumor T and pathologic stage. ROC assays confirmed the diagnostic value of COL10A1 expression in screening GC samples from normal samples. Survival data displayed that patients with high COL10A1 expression exhibited a shorter OS and DSS than those with low COL10A1 expression. We obtained a predictive nomogram, which could better predict the COL10A1 expression by virtue of discrimination and calibration. The prognostic value of COL10A1 expression was further confirmed in GSE84426 datasets. Immune assays revealed that COL10A1 expression was associated with tumor-filtrating immune cells, like CD8 T cells, cytotoxic cells, DC, eosinophils, iDC, macrophages, mast cells, NK CD56dim cells, NK cells, pDC, T helper cells, Tem, Th1 cells, Th17 cells, and Treg. Overall, we firstly proved that COL10A1 may be a novel and valuable prognostic and diagnostic factor for GC patients. In addition, COL10A1 has potential to be an immune indicator in GC.

Secreted frizzled related protein 2 protects cells from apoptosis by blocking the effect of canonical Wnt3a.

We have demonstrated that mesenchymal stem cells overexpressing the survival gene Akt can confer paracrine protection to ischemic myocytes both in vivo and in vitro through the release of secreted frizzled related protein 2 (Sfrp2). However, the mechanisms mediating these effects of Sfrp2 have not been fully elucidated. In this study, we studied rat cardiomyoblasts subjected to hypoxia reoxygenation (HR) injury to test the hypothesis that Sfrp2 exerts anti-apoptotic effect by antagonizing pro-apoptotic properties of specific Wnt ligands. We examined the effect of Wnt3a and Sfrp2 on HR-induced apoptosis. Wnt3a significantly increased cellular caspase activities and TUNEL staining in response to HR. Sfrp2 attenuated significantly Wnt3a-induced caspase activities in a concentration dependent fashion. Using a solid phase binding assay, our data demonstrates that Sfrp2 physically binds to Wnt3a. In addition, we observed that Sfrp2 dramatically inhibits the beta-catenin/TCF transcriptional activities induced by Wnt3a. Impressively, Dickkopf-1, a protein that binds to the Wnt coreceptor LRP, significantly inhibited the Wnt3a-activated caspase and transcriptional activities. Similarly, siRNA against beta-catenin markedly inhibited the Wnt3a-activated caspase activities. Consistent with this, significantly fewer TUNEL positive cells were observed in siRNA transfected cells than in control cells. Together, our data provide strong evidence to support the notion that Wnt3a is a canonical Wnt with pro-apoptotic action whose cellular activity is prevented by Sfrp2 through, at least in part, the direct binding of these molecules. These results can explain the in vivo protective effect of Sfrp2 and highlight its therapeutic potential for the ischemic heart.

Contribution of Cdc42 to cholesterol efflux in fibroblasts from Tangier disease and Werner syndrome.

Atherosclerotic cardiovascular disease is a life-threatening disorder. Cholesterol efflux from the cells is the rate-limiting step in regulating the intracellular cholesterol content as well as raft structure in the plasma membrane. The defect of cholesterol efflux leads to the development of atherosclerosis. Tangier disease (TD), a hereditary high-density lipoprotein deficiency, is characterized by the presence of defective cellular cholesterol efflux. Using the cDNA subtraction technique, we found that expression of Cdc42 was decreased markedly in fibroblasts and macrophages from patients with TD. Madin-Darby canine kidney cells expressing the dominant-negative form of Cdc42 had a reduced lipid efflux; inversely, cells expressing the active form had increased efflux. Furthermore, we found that cellular lipid efflux was defective and Cdc42 was reduced in fibroblasts from a premature aging disorder, Werner syndrome. Complementation experiments using an adenovirus carrying wild-type Cdc42 successfully corrected impaired lipid efflux in Werner syndrome cells. We concluded that Cdc42 may play important roles in cellular cholesterol efflux and that dysregulation of this type of RhoGTPase might lead to the development of atherosclerotic cardiovascular disease.

Probucol enhances the expression of human hepatic scavenger receptor class B type I, possibly through a species-specific mechanism.

OBJECTIVE: Scavenger receptor class B type I (SR-BI) is a major receptor for high-density lipoproteins (HDL) in the liver, which is the terminus of reverse cholesterol transport. Overexpression of SR-BI attenuated experimental atherosclerosis in murine models, concomitant with a reduction in plasma HDL-cholesterol levels. Probucol is known to be a potent hypolipidemic drug to regress xanthoma formation and carotid atherosclerosis in conjunction with a marked reduction in HDL-cholesterol levels. The aim of the present study was to know the effect of probucol on the expression of SR-BI and the underlying mechanism. METHODS AND RESULTS: We found that probucol increased the expression of SR-BI proteins in in vitro human liver cells and an in vivo rabbit model, but not in wild-type C57Bl6 mice. The decay curve of SR-BI protein was markedly retarded in probucol-treated HepG2 cells in the presence of cycloheximide, indicating that probucol may stabilize human SR-BI protein. To determine the underlying mechanism for the observed species-specific effect, we conducted the following host-swap experiments, in which SR-BI was transfected or expressed in heterologous cells or hosts. Probucol did not increase human SR-BI protein in the liver of transgenic mice carrying the entire human SR-BI genome. Although probucol could stabilize even murine SR-BI, when transfected into a human cell line, HepG2, human SR-BI was not stabilized in a mouse hepatoma cell line, Hepa 1-6, treated with probucol. CONCLUSIONS: Probucol enhances hepatic SR-BI protein expression, possibly through species-specific stabilization of the protein.