Polyoxypregnanes as safe, potent, and specific ABCB1-inhibitory pro-drugs to overcome multidrug resistance in cancer chemotherapy in vitro and in vivo

Multidrug resistance (MDR) mediated by ATP binding cassette subfamily B member 1 (ABCB1) is significantly hindering effective cancer chemotherapy. However, currently, no ABCB1-inhibitory drugs have been approved to treat MDR cancer clinically, mainly due to the inhibitor specificity, toxicity, and drug interactions. Here, we reported that three polyoxypregnanes (POPs) as the most abundant constituents of Marsdenia tenacissima (M. tenacissima) were novel ABCB1-modulatory pro-drugs, which underwent intestinal microbiota-mediated biotransformation in vivo to generate active metabolites. The metabolites at non-toxic concentrations restored chemosensitivity in ABCB1-overexpressing cancer cells via inhibiting ABCB1 efflux activity without changing ABCB1 protein expression, which were further identified as specific non-competitive inhibitors of ABCB1 showing multiple binding sites within ABCB1 drug cavity. These POPs did not exhibit ABCB1/drug metabolizing enzymes interplay, and their repeated administration generated predictable pharmacokinetic interaction with paclitaxel without obvious toxicity in vivo. We further showed that these POPs enhanced the accumulation of paclitaxel in tumors and overcame ABCB1-mediated chemoresistance. The results suggested that these POPs had the potential to be developed as safe, potent, and specific pro-drugs to reverse ABCB1-mediated MDR. Our work also provided scientific evidence for the use of M. tenacissima in combinational chemotherapy.

Assessment of Apparent Internal Carotid Tandem Occlusion on High-Resolution Vessel Wall Imaging: Comparison with Digital Subtraction Angiography

BACKGROUND AND PURPOSE

Not all tandem occlusions diagnosed on traditional vascular imaging modalities, such as MRA, represent actual complete ICA occlusion. This study aimed to explore the utility of high-resolution vessel wall imaging in identifying true ICA tandem occlusions and screening patients for their suitability for endovascular recanalization.

MATERIALS AND METHODS

Patients with no signal in the ICA on MRA were retrospectively reviewed. Two neuroradiologists independently reviewed their high-resolution vessel wall images to assess whether there were true tandem occlusions and categorized all cases into intracranial ICA occlusion, extracranial ICA occlusion, tandem occlusion, or near-occlusion. DSA classified patient images into the same 4 categories, which were used as the comparison with high-resolution vessel wall imaging. The suitability for recanalization of occluded vessels was evaluated on high-resolution vessel wall imaging compared with DSA.

RESULTS

Forty-five patients with no ICA signal on MRA who had available high-resolution vessel wall imaging and DSA images were included. Among the 34 patients (34/45, 75.6%) with tandem occlusions on DSA, 18 cases also showed tandem occlusions on high-resolution vessel wall imaging. The remaining 16 patients, intracranial ICA, extracranial ICA occlusions and near-occlusions were found in 2, 6, and 8 patients, respectively, on the basis of high-resolution vessel wall imaging. A total of 20 cases (20/45, 44.4%) were considered suitable for recanalization on the basis of both DSA and high-resolution vessel wall imaging. Among the 25 patients deemed unsuitable for recanalization by DSA, 11 were deemed suitable for recanalization by high-resolution vessel wall imaging.

CONCLUSIONS

High-resolution vessel wall imaging could allow identification of true ICA tandem occlusion in patients with an absence of signal on MRA. Findings on high-resolution vessel wall imaging can be used to screen more suitable candidates for recanalization therapy.

VCP/p97/Cdc48, A Linking of Protein Homeostasis and Cancer Therapy

VCP/p97/Cdc48, a member of the ATPases associated with diverse cellular activities (AAA) family, is necessary for the endoplasmic-reticulum-associated protein degradation (ERAD) pathway to maintain protein homeostasis. Overwhelming proteotoxic stress drove cancer cells to enhance VCP/p97/Cdc48-associated ERAD to maintain protein homeostasis for survival, demonstrating that VCP/p97/Cdc48 expression was positively correlated with cancer prognosis. More studies revealed that targeting VCP/p97/Cdc48 could be a potential target in cancer therapy. CB-5083, a novel inhibitor of VCP/p97/Cdc48, is in clinical trials as the first VCP/p97/Cdc48- inhibiting drug for cancer therapy. Here, we discuss the relationship between VCP/p97/Cdc48, ERAD, protein homeostasis and cancer therapy.

Characterization and adsorption of a Lactobacillus plantarum virulent phage

Bacteriophage infection of lactic acid bacteria is considered one of the biggest worldwide problems in the food industry. Bacteriophages may cause negative effects on the fermentation of various dairy-based products. A virulent bacteriophage was isolated from an abnormal fermentation liquid of Lactobacillus plantarum IMAU10120. The characterization and influence of temperature, pH, divalent cations, and chloramphenicol on the adsorption ability of this phage were evaluated. The results showed that this phage belonged to the Siphoviridae family. It exhibited a burst time of 135 min and a burst size of approximately 215 counts expressed per milliliter per infective center. No significant effect was shown to influence its viability and adsorption at 10 to 37°C. More than 90% of phages exhibited infectivity from pH 5 to 9. Divalent ions and chloramphenicol did not have a significant influence on the adsorption of this phage. The information obtained in this study will enrich the database of lactobacilli virulent phages and provide a basis of information for the control of phages in the food fermentation industry.

Stronger selective constraint on downstream genes in the oxidative phosphorylation pathway of cetaceans

The oxidative phosphorylation (OXPHOS) pathway is an efficient way to produce energy via adenosine triphosphate (ATP), which is critical for sustaining an energy supply for cetaceans in a hypoxic environment. Several studies have shown that natural selection may shape the evolution of the genes involved in OXPHOS. However, how network architecture drives OXPHOS protein sequence evolution remains poorly explored. Here, we investigated the evolutionary patterns of genes in the OXPHOS pathway across six cetacean genomes within the framework of a functional network. Our results show a negative correlation between the strength of purifying selection and pathway position. This result indicates that downstream genes were subjected to stronger evolutionary constraints than upstream genes, which may be due to the dual function of ATP synthase in the OXPHOS pathway. Additionally, there was a positive correlation between codon usage bias and omega (ω = dN/dS) and a negative correlation with synonymous substitution rate (dS), indicating that the stronger selective constraint on genes (with less biased codon usage) along the OXPHOS pathway is attributable to an increase in the rate of synonymous substitution. Surprisingly, there was no significant correlation between protein-protein interactions and the evolutionary estimates, implying that highly connected enzymes may not always show greater evolutionary constraints. Compared with that observed for terrestrial mammals, we found that the signature of positive selection detected in five genes (ATP5J, LHPP, PPA1, UQCRC1 and UQCRQ) was cetacean-specific, reflecting the importance of OXPHOS for survival in hypoxic, aquatic environments.

TP53INP1 Downregulation Activates a p73-Dependent DUSP10/ERK Signaling Pathway to Promote Metastasis of Hepatocellular Carcinoma

Identifying critical factors involved in the metastatic progression of hepatocellular carcinoma (HCC) may offer important therapeutic opportunities. Here, we report that the proapoptotic stress response factor TP53INP1 is often selectively downregulated in advanced stage IV and metastatic human HCC tumors. Mechanistic investigations revealed that TP53INP1 downregulation in early-stage HCC cells promoted metastasis via DUSP10 phosphatase-mediated activation of the ERK pathway. The DUSP10 promoter included putative binding sites for p73 directly implicated in modulation by TP53INP1. Overall, our findings show how TP53INP1 plays a critical role in limiting the progression of early-stage HCC, with implications for developing new therapeutic strategies to attack metastatic HCC. Cancer Res; 77(17); 4602-12. ©2017 AACR.

Abstract 2895: Octamer-4/microRNA-1246 signaling axis drives Wnt/β-catenin activation in liver cancer stem cells

Hepatocellular carcinoma (HCC), the main type of liver cancer in human, is one of the most prevalent and deadly malignancies in the world. Despite advances in therapy, prognosis remains dismal, largely attributed by our limited understanding on information related to the progressive development of the disease, particularly in their cancer-initiating and stem cell-like properties. Wnt/β-catenin signaling is activated in CD133 liver cancer stem cells (CSC), a subset of cells known to be a root of tumor recurrence and therapy resistance in HCC. However, the regulatory mechanism of this pathway in CSCs remains unclear. Here, we show that human miRNA, miR-1246, promotes cancer stemness including self-renewal, drug resistance, tumorigencity and metastasis by activation of Wnt/β-catenin pathway via suppressing the expression of AXIN2 and GSK3β, two key members of the β-catenin destruction complex. This observation was validated by both in vitro and in vivo functional / cell biological studies on HCC cell lines with or without miR-1246 expression modulated by lentiviral based knockdown and overexpression strategies as well as in miR-1246 repressed HCC cells with concomitant expression of wild-type or constitutively active β-catenin. Clinically, high endogenous and circulating miR-1246 was identified in HCC clinical samples and correlated with a worse prognosis. Further functional analysis identified Oct4 to be the direct upstream regulator of miR-1246, which cooperatively drive β-catenin activation in liver CSCs. In conclusion, our findings not only uncover the non-canonical regulation of Wnt/β-catenin in liver CSCs by Oct4/miR-1246 signaling axis, but also provide a novel diagnostic marker as well as therapeutic intervention for HCC.

Citation Format: Stella Chai, Kai-Yu Ng, Man Tong, Eunice Y. Lau, Terence K. Lee, Kwok Wah Chan, Yun Fei Yuan, Tan To Cheung, Siu Tim Cheung, Xiao Qi Wang, Nathalie Wong, Chung Mau Lo, Kwan Man, Xin Yuan Guan, Stephanie K. Ma. Octamer-4/microRNA-1246 signaling axis drives Wnt/β-catenin activation in liver cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2895. doi:10.1158/1538-7445.AM2017-2895

Abstract LB-139: PRMT6-dependent CRAF/ERK signaling regulates cancer stem cell plasticity in liver cancer

Hepatocellular carcinoma (HCC), the major type of liver cancer, remains one of the most prevalent and deadliest cancer types in the world. Contemporary challenge in treating HCC has been the common therapy resistance and recurrence after therapy, all of which have been reported to be associated with stem-like behavior of cancer cells. Our group has previously identified a functional liver cancer stem cell (CSC) subset marked by the CD133 cell surface phenotype. Utilizing a PCR array encompassing diverse human chromatin modifiers, protein arginine methyltransferase 6 (PRMT6) was found to be differentially down-regulated in CD133+ liver CSCs of human HCC cells as well as CD133 enriched chemoresistant hepatospheres as compared to their counterparts. Clinically, reduced PRMT6 expression was detected in HCC specimens and correlated with a higher risk of metastasis. PRMT6 negatively regulated diverse in vitro cancer stem cell properties of HCC cells including self-renewal, therapy resistance, metastasis and expression of CSC and pluripotency markers. In addition, PRMT6 also suppressed in vivo tumor initiation and serial transplantation. Surprising, contrary to its usual localization in the nucleus as a chromatin modification enzyme mediating histone H3R2 methylation, we found PRMT6 to be predominantly expressed in the cytoplasm in normal liver and HCC cells. Through tandem affinity purification and subsequent mass spectrometry profiling, we identified CRAF, a serine/threonine-protein kinase, as a novel cytoplasmic protein partner of PRMT6. Binding of PRMT6 to CRAF inhibited its kinase activity through site-specific arginine methylation, resulting in inhibition of ERK-mediated CSC plasticity in HCC, demonstrated through in vivo / in vitro methylation assays, kinase assay and functional rescue experiments with the ERK inhibitor U0126. The link between PRMT6, ERK and cancer stemness was further substantiated in primary human normal liver and HCC organoids with or without PRMT6 modulated. Taken together, we found PRMT6 to be down-regulated in the liver CSC subset and to be functionally involved in regulating liver CSC plasticity via an unprecedented role in the cytoplasm through suppression of CRAF/ERK cascade.

Citation Format: Lok Hei Chan, Lei Zhou, Kai Yu Ng, Tin Lok Wong, Stella Chai, Terence K Lee, Xin Yuan Guan, Yick Pang Ching, Chung Mau Lo, Kwan Man, Benedetta Artegiani, Hans Clevers, Helen H Yan, Suet Yi Leung, Stèphane Richard, Michael SY Huen, Stephanie Ma. PRMT6-dependent CRAF/ERK signaling regulates cancer stem cell plasticity in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-139. doi:10.1158/1538-7445.AM2017-LB-139

Reversal of multidrug resistance by Marsdenia tenacissima and its main active ingredients polyoxypregnanes

ETHNOPHARMACOLOGICAL RELEVANCE

Multidrug resistance (MDR) of cancer is often associated with the overexpression of ATP-binding cassette (ABC) transporters, such as P-glycoprotein (P-gp), multidrug resistance-associated protein-1 (MRP-1) and breast cancer resistance protein (BCRP or ABCG2), in cancer cells, which facilitates the active efflux of a wide variety of chemotherapeutic drugs out of the cells. Marsdenia tenacissima is a traditional Chinese medicinal herb that has long been clinically used for treatment of cancers, particularly in combinational use with anticancer drugs. Polyoxypregnanes (POPs) are identified as main constituents of this herb, and three of them have been reported to exhibit P-gp modulatory effect and thus reverse MDR. Therefore, it is of great necessity to investigate more POPs that have potential to reverse transporters-mediated MDR.

AIM OF THE STUDY

We aimed to identify POPs as the chemical basis responsible for circumventing ABC transporters-mediated MDR by M. tenacissima.

MATERIALS AND METHODS

The MDR reversal effects of M. tenacissima crude extract together with a series of isolated POPs were evaluated on several MDR cancer cell lines that overexpress P-gp, MRP1 or ABCG2. The activities of P-gp, MRP1 and ABCG2 were determined by the flow cytometry-based substrate efflux assay. Molecular docking of POPs to a three-dimensional human P-gp homology structure was also performed.

RESULTS

The crude extract of M. tenacissima was firstly found to circumvent P-gp-mediated MDR. Then, 11 polyoxypregnane compounds (POPs) isolated from this herb were found to overcome P-gp-, MRP1- and/or ABCG2-mediated MDR. Further mechanistic study delineated that the reversal of MDR by these POPs was due to significant increase in the intracellular concentrations of the substrate anticancer drugs via their inhibition of different ABC transporter-mediated efflux activities. Furthermore, molecular docking revealed that POPs with P-gp modulatory effect bound to P-gp and fitted well into the cavity between the alpha and beta subunit of P-gp via forming hydrogen bonds. In addition, several key structural determinants for inhibition of P-gp, MRP1 or ABCG2 by POPs were illustrated.

CONCLUSIONS

Our findings advocated the rational use of M. tenacissima to enhance efficacies of conventional anticancer drugs in tumors with ABC drug transporters-mediated MDR. Furthermore, 11 POPs were found to contribute to MDR reversal effect of M. tenacissima via inhibition of different ABC efflux transporters.

Octamer 4/microRNA-1246 signaling axis drives Wnt/β-catenin activation in liver cancer stem cells

Wnt/β-catenin signaling is activated in CD133 liver cancer stem cells (CSCs), a subset of cells known to be a root of tumor recurrence and therapy resistance in hepatocellular carcinoma (HCC). However, the regulatory mechanism of this pathway in CSCs remains unclear. Here, we show that human microRNA (miRNA), miR-1246, promotes cancer stemness, including self-renewal, drug resistance, tumorigencity, and metastasis, by activation of the Wnt/β-catenin pathway through suppressing the expression of AXIN2 and glycogen synthase kinase 3β (GSK3β), two key members of the β-catenin destruction complex. Clinically, high endogenous and circulating miR-1246 was identified in HCC clinical samples and correlated with a worse prognosis. Further functional analysis identified octamer 4 (Oct4) to be the direct upstream regulator of miR-1246, which cooperatively drive β-catenin activation in liver CSCs.

CONCLUSION

These findings uncover the noncanonical regulation of Wnt/β-catenin in liver CSCs by the Oct4/miR-1246 signaling axis, and also provide a novel diagnostic marker as well as therapeutic intervention for HCC. (Hepatology 2016;64:2062-2076).

Polyoxypregnane steroids with an open-chain sugar moiety from Marsdenia tenacissima and their chemoresistance reversal activity

A polyoxypregnane aglycone, 12β-O-acetyl-11α-O-isobutyryltenacigenin B, and four polyoxypregnane glycosides with a pachybionic acid ester moiety, 12β-O-acetyl-3-O-(6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandronyl)-11α-O-isobutyryltenacigenin B, 12β-O-acetyl-3-O-(6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandronyl)-11α-O-tigloyltenacigenin B, 12β-O-acetyl-3-O-(6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandronyl)-11α-O-2-methylbutyryltenacigenin B, and 12β-O-acetyl-3-O-(β-D-glucopyranosyl-(1→4)-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-D-oleandronyl)-11α-O-tigloyltenacigenin B, were isolated from the canes of Marsdenia tenacissima, together with a disaccharide derivative. Their structures were elucidated by extensive spectroscopic analysis, and the absolute configurations were further determined by X-ray crystallographic analysis. With the exception of the disaccharide derivative, all five compounds are unusual naturally occurring polyoxypregnane glycosides bearing an open-chain sugar moiety. Two of these exhibit a wide spectrum of chemoresistance reversal activity, and potential mechanisms were studied accordingly.

Neuropilin-2 promotes tumourigenicity and metastasis in oesophageal squamous cell carcinoma through ERK-MAPK-ETV4-MMP-E-cadherin deregulation

Oesophageal squamous cell carcinoma (ESCC) is the most common histological subtype of oesophageal cancer. The disease is particularly prevalent in southern China. The incidence of the disease is on the rise and its overall survival rate remains dismal. Identification and characterization of better molecular markers for early detection and therapeutic targeting are urgently needed. Here, we report levels of transmembrane and soluble neuropilin-2 (NRP2) to be significantly up-regulated in ESCC, and to correlate positively with advanced tumour stage, lymph node metastasis, less favourable R category and worse overall patient survival. NRP2 up-regulation in ESCC was in part a result of gene amplification at chromosome 2q. NRP2 overexpression promoted clonogenicity, angiogenesis and metastasis in ESCC in vitro, while NRP2 silencing by lentiviral knockdown or neutralizing antibody resulted in a contrary effect. This observation was extended in vivo in animal models of subcutaneous tumourigenicity and tail vein metastasis. Mechanistically, overexpression of NRP2 induced expression of ERK MAP kinase and the transcription factor ETV4, leading to enhanced MMP-2 and MMP-9 activity and, as a consequence, suppression of E-cadherin. In summary, NRP2 promotes tumourigenesis and metastasis in ESCC through deregulation of ERK-MAPK-ETV4-MMP-E-cadherin signalling. NRP2 represents a potential diagnostic or prognostic biomarker and therapeutic target for ESCC. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Cancer-Associated Fibroblasts Regulate Tumor-Initiating Cell Plasticity in Hepatocellular Carcinoma through c-Met/FRA1/HEY1 Signaling

Like normal stem cells, tumor-initiating cells (T-ICs) are regulated extrinsically within the tumor microenvironment. Because HCC develops primarily in the context of cirrhosis, in which there is an enrichment of activated fibroblasts, we hypothesized that cancer-associated fibroblasts (CAFs) would regulate liver T-ICs. We found that the presence of α-SMA(+) CAFs correlates with poor clinical outcome. CAF-derived HGF regulates liver T-ICs via activation of FRA1 in an Erk1,2-dependent manner. Further functional analysis identifies HEY1 as a direct downstream effector of FRA1. Using the STAM NASH-HCC mouse model, we find that HGF-induced FRA1 activation is associated with the fibrosis-dependent development of HCC. Thus, targeting the CAF-derived, HGF-mediated c-Met/FRA1/HEY1 cascade may be a therapeutic strategy for the treatment of HCC.

Virtual classroom helps medical education for both Chinese and foreign students

AIMS

The rapid development of computer and internet technology has a strong influence over one's quality of education within different fields of study. To determine the potential benefits of introducing internet into medical school classes, a pilot study was conducted in three different Chinese medical schools.

MATERIALS AND METHODS

Seven hundred and eight medical school undergraduates, 385 dental school students and 366 foreign students were randomly recruited to complete a self-administered questionnaire. The contents included personal information, current usage of computer and internet, and attitudes towards the computerised teaching methods. Two forum groups were created using instant message software and were randomly assigned to two classes, allowing students to freely ask or discuss questions with the help of their teachers in these two virtual classrooms.

RESULTS

All 1539 questionnaires were accepted and analysed. Although there were some differences between Chinese and foreign undergraduates, both group of students were highly proficient in internet usage and navigation. Overwhelmingly, 88.37% of the students owned a computer and frequently logged onto the internet. Most of them believed that the internet is a helpful adjunct to their studies and held positive attitudes towards computerised teaching. Compared to the classes that were not assigned internet forums, the two experimental classes performed significantly better on the examination.

CONCLUSIONS

Our results suggest that computerised teaching methods have significant potential to assist in learning for both Chinese and foreign medical undergraduates.

Abstract 2874: Regulatory role of miRNA-1246 and Wnt/β-catenin pathway interaction in CD133+ liver cancer stem cells-driven hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the main type of liver cancer in human, is one of the most prevalent and deadly malignancies in the world. Despite advances in therapy, prognosis remains dismal, largely attributed to our limited understanding on information related to the progressive development of the disease, particularly in their cancer-initiating and stem cell-like properties. There is increasing evidence in recent years to support the role of miRNAs in the regulation of cancer stem cell (CSC) maintenance. However, miRNAs in hepatic CSCs remain understudied. Our group has previously identified a functional subset of liver CSCs marked by the CD133 phenotype. Utilizing a comprehensive transcriptome sequencing approach, we recently compared the differential miRNA profiles of CD133+ liver CSCs and CD133- differentiated cells isolated from HCC cells Huh7 and PLC8024, and identified a significant up-regulation of miR-1246 in the CD133+ liver CSC subset. In silico prediction analysis and luciferase reporter assays found miR-1246 to target both GSK-3β and AXIN2, two key players of the Wnt/β-catenin degradation complex. This is particularly interesting as we and others have previously found the Wnt/β-catenin signaling pathway to be significantly deregulated in CD133+ liver cells as well as in HCC. miR-1246 up-regulation was further validated in additional CD133 sorted HCC cells. Expression of miR-1246 and CD133 was also found to positively correlate across a panel of liver cell lines. Functional studies were subsequently performed using lentiviral-based miR-1246 knockdown in Hep3B and Huh7. miR-1246 deregulation was closely associated with an altered ability of HCC cells to proliferate, self-renew, invade, migrate, induce capillary tube formation in endothelial cells and initiate tumor formation in vivo. Notably, reexpression of constitutively active β-catenin in HCC cells with stable miR-1246 repression rescued this altered phenotype. Knockdown of miR-1246 was associated with increased GSK-3β and AXIN2, concomitant with decreased β-catenin expression, as detected by immunofluorescence. TOP/FOP luciferase signal was also significantly down-regulated following miR-1246 suppression in both CD133-expressing Hep3B and Huh7 cells. By in vivo ubiquitylation assay, a higher level of ubiquitinated β-catenin was observed following miR-1246 knockdown in both Hep3B and Huh7 cells suggesting the decrease in β-catenin was a result of its ubiquitylation. Consistently, downstream targets of the Wnt/β-catenin pathway, including cyclin-D1, c-myc and MMP7, were also likewise decreased at the transcriptional level following miR-1246 knockdown. Taken together, we found miR-1246 to be functionally involved in driving CD133+ liver CSCs through activation of the Wnt/β-catenin and its downstream signaling cascade by directly targeting GSK-3β and AXIN2.

Citation Format: Stella Chai, Kai Yu Ng, Man Tong, Siu Tim Cheung, Xin-Yuan Guan, Stephanie Ma. Regulatory role of miRNA-1246 and Wnt/β-catenin pathway interaction in CD133+ liver cancer stem cells-driven hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2874. doi:10.1158/1538-7445.AM2015-2874

Neonatal Overfeeding in Female Mice Predisposes the Development of Obesity in their Male Offspring via Altered Central Leptin Signalling

The prevalence of obesity among child-bearing women has increased significantly. The adverse consequences of maternal obesity on the descendants have been well accepted, although few studies have examined the underlying mechanisms. We investigated whether neonatal overfeeding in female mice alters metabolic phenotypes in the offspring and whether hypothalamic leptin signalling is involved. Neonatal overfeeding was induced by reducing the litter size to three pups per litter, in contrast to normal litter size of 10 pups per litter. Normal and neonatally overfed female mice were bred with normal male mice, and offspring of overfeeding mothers (OOM) and control mothers (OCM) were generated. We examined body weight, daily food intake, leptin responsiveness and the number of positive neurones for phosphorylated-signal transducer and activator of transcription 3 (pSTAT3) along with neuropeptide Y (NPY) in the arcuate nucleus of the hypothalamus (ARH) and NPY in the nucleus tractus solitarius (NTS) of the brain stem. The body weight and daily food intake of OOM were significantly higher than those of OCM. Leptin significantly reduced food intake and increased the number of pSTAT3 positive neurones in the ARH of OCM mice, whereas no significant changes in food intake and pSTAT3 neurones were found in leptin-treated OOM mice. The number of NPY neurones in the ARH and NTS of the OOM mice was significantly higher than that of OCM mice. The results of the present study indicate that the obese phenotype from mothers can be passed onto the subsequent generation, which is possibly associated with hypothalamic leptin resistance.

Regulatory role of miR-142-3p on the functional hepatic cancer stem cell marker CD133

Tumor relapse after therapy typifies hepatocellular carcinoma (HCC) and is believed to be attributable to residual cancer stem cells (CSCs) that survive treatment. We have previously identified a CSC population derived from HCC that is characterized by CD133. Despite our growing knowledge of the importance of this subset of cells in driving HCC, the regulatory mechanism of CD133 is not known. Epigenetic changes are believed to be essential in the control of cancer and stem cells. Here, we report the epigenetic regulation of CD133 by miR-142-3p. The interaction between CD133 and miR-142-3p was identified by in silico prediction and substantiated by luciferase reporter analysis. Expression of CD133 was found to be inversely correlated with miR-142-3p in HCC clinical samples as well as in cell lines. Importantly, lower miR-142-3p expression in HCC was significantly associated with worst survival. Functional studies with miR-142-3p stably transduced in HCC cells demonstrated a diminished ability to self-renew, initiate tumor growth, invade, migrate, induce angiogenesis and resist chemotherapy. Rescue experiments whereby CD133 and miR-142-3p is simultaneously overexpressed compensated the deregulated ability of the cells to confer these features. Thus, miR-142-3p directly targets CD133 to regulate its ability to confer cancer and stem cell-like features in HCC.

Abstract LB-53: Regulatory role of miR-142-3p on the functional hepatic cancer stem cell marker CD133

Tumor relapse after therapy typifies hepatocellular carcinoma (HCC) and is believed to be attributable to residual cancer stem cells (CSCs) that survive initial treatment. We have previously identified a CSC population derived from HCC that is characterized by the expression of the transmembrane glycoprotein, CD133. Despite our growing knowledge of the importance of a functional CD133+ liver CSC subset in driving HCC, the regulatory mechanism of CD133 is not known. Epigenetic changes are believed to be essential in the control of cancer and stem cells. We report here the dynamic epigenetic regulation of the functional liver CSC marker CD133 by promoter methylation and miR-142-3p regulation. Unlike in other tumor types, we found DNA methylation to only play a minor role in the control of CD133 expression in HCC. More importantly, our results revealed that miR-142-3p plays an integral part in the direct targeting of CD133. The interaction between the 3’UTR of CD133 and miR-142-3p was identified by in silico prediction and substantiated by luciferase reporter analysis. Expression of CD133 was found to be inversely correlated with miR-142-3p in a panel of liver cell lines and HCC clinical samples. Functional studies with miR-142-3p stably transduced in HCC cells demonstrated a diminished ability to self-renew, initiate tumor growth, invade, migrate, induce capillary tube formation in endothelial cells and resist standard chemotherapy. Rescue experiments whereby CD133 and miR-142-3p is simultaneously overexpressed compensated the deregulated ability of the cells to confer these cancer and stem cell-like features. In summary, our findings suggestion promoter methylation to only play a minor role in the regulation of CD133 in HCC; and that miR-142-3p directly targets CD133 to regulate its ability to confer cancer and stem cell-like features in HCC.

Citation Format: Kai Yu Ng, Stella Chai, Man Tong, Pak Shing Kwan, Yuen Piu Chan, Terence Kin Wah Lee, Nathalie Wong, Xin-Yuan Guan, Stephanie Ma. Regulatory role of miR-142-3p on the functional hepatic cancer stem cell marker CD133. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-53. doi:10.1158/1538-7445.AM2014-LB-53

Abstract 1955: Regulatory role of miRNA-1246 and Wnt/β-catenin pathway interaction in CD133+ liver cancer stem cells-driven hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the main type of liver cancer in human, is one of the most prevalent and deadly malignancies in the world. Despite advances in therapy, prognosis remains dismal, largely attributed to our limited understanding on information related to the progressive development of the disease, particularly in their cancer-initiating and stem cell-like properties. There is increasing evidence in recent years to support the role of miRNAs in the regulation of cancer stem cell (CSC) maintenance. However, miRNAs in hepatic CSCs remain understudied. Our group has previously identified a functional subset of liver CSCs marked by the CD133 phenotype (1-2). Utilizing a comprehensive transcriptome sequencing approach, we recently compared the differential miRNA profiles of CD133+ liver CSCs and CD133- differentiated cells isolated from HCC cells Huh7 and PLC8024, and identified a significant up-regulation of miR-1246 in CD133+ liver CSC subset. This observation was further validated in additional CD133 sorted HCC cells (Huh7, PLC8024, HepG2 and SNU182). Expression of miR-1246 and CD133 was also found to positively correlate across a panel of liver cell lines. Functional studies were subsequently performed using lentiviral-based miR-1246 knockdown in Huh7 and HepG2 or miR-1246 overexpression in LO2 HCC cells. miR-1246 deregulation was closely associated with an altered ability of HCC cells to proliferate, self-renew, invade, migrate, induce capillary tube formation in endothelial cells and initiate tumor formation in vivo. By in silico prediction, we then identified GSK3β and AXIN2, both key players of the Wnt/β-catenin degradation complex, as candidate downstream targets of miR-1246. Consistent with this finding, our group has also previously found β-catenin to be preferentially overexpressed in the CD133+ liver CSC subset (1). Real-time qPCR, Western blot and luciferase reporter assay further confirmed the bona fide interaction between miR-1246 and GSK3β or miR-1246 and AXIN2. miR-1246 expression positively correlated with β-catenin. Transient overexpression of miR-1246 mimic resulted in TCF/LEF activation in both CD133-expressing Huh7 and HepG2 cells, concomitant with deregulation of downstream targets of the Wnt/β-catenin pathway, including cyclin-D1, MMP7 and c-myc. Taken together, miR-1246 is functionally involved in driving CD133+ liver CSCs through activation of the Wnt/β-catenin and its downstream signaling cascade.

References:

1. Ma S, Chan KW, Hu L, et al. (2007) Gastroenterology 132:2546-52.

2. Ma S, Tang KH, Chan YP, et al. (2010) Cell Stem Cell 7:697-707.

Citation Format: Stella Chai, Kai Yu Ng, Man Tong, Xin Yuan Guan, Stephanie Ma. Regulatory role of miRNA-1246 and Wnt/β-catenin pathway interaction in CD133+ liver cancer stem cells-driven hepatocellular carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1955. doi:10.1158/1538-7445.AM2014-1955

Polyoxypregnane steroids from the stems of Marsdenia tenacissima

A new polyoxypregnane aglycone, tenacigenin D (1), and seven new C21 steroid glycosides, tenacissimosides D-J (2-8), were isolated from the stems of Marsdenia tenacissima. Their structures were determined by interpretation of their 1D and 2D NMR and other spectroscopic data, as well as by comparison with published values for related known compounds. Compound 1 was found to circumvent P-glycoprotein (P-gp)-mediated multidrug resistance through an inhibitory effect on P-gp with a similar potency to verapamil. In addition, compound 1 potentiated the activity of erlotinib and gefitinib in epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI)-resistant non-small-cell lung cancer cells.

Clinical implications of microRNAs in liver cancer stem cells

The prognosis of patients diagnosed with hepatocellular carcinoma (HCC) is often dismal, mainly due to late presentation, high recurrence rate, and frequent resistance to chemotherapy and radiotherapy. Accumulating evidence on the differential microRNA (miRNA) expression patterns between non-tumor and HCC tissues or between liver cancer stem cells (CSCs) and non-CSC subsets and the significant clinical implications of these differences suggest that miRNAs are a promising, non-invasive marker for the prognosis and diagnosis of the disease. This perspective article summarizes the current knowledge of miRNAs in liver CSCs and highlights the need for further investigations of the role of miRNAs in regulating liver CSC subsets for possible future clinical applications.

Circumvention of multi-drug resistance of cancer cells by Chinese herbal medicines

Multi-drug resistance (MDR) of cancer cells severely limits therapeutic outcomes. A proposed mechanism for MDR involves the efflux of anti-cancer drugs from cancer cells, primarily mediated by ATP-binding cassette (ABC) membrane transporters including P-glycoprotein. This article reviews the recent progress of using active ingredients, extracts and formulae from Chinese medicine (CM) in circumventing ABC transporters-mediated MDR. Among the ABC transporters, Pgp is the most extensively studied for its role in MDR reversal effects. While other MDR reversal mechanisms remain unclear, Pgp inhibition is a criterion for further mechanistic study. More mechanistic studies are needed to fully establish the pharmacological effects of potential MDR reversing agents.

Defects in articular cartilage metabolism and early arthritis in fibroblast growth factor receptor 3 deficient mice

Fibroblast growth factor (FGF) receptor 3 has been identified as a key regulator of endochondral bone development and of post-natal bone metabolism through its action on growth plate chondrocytes and osteoblasts, respectively. It has also been shown to promote chondrogenesis and cartilage production by cultured pre-chondrogenic cells in response to FGF18. In the current studies, we show that the absence of signaling through Fgfr3 in the joints of Fgfr3(-/-) mice leads to premature cartilage degeneration and early arthritis. Degenerative changes in cartilage matrix included excessive proteolysis of aggrecan core protein and type II collagen, as measured by neo-epitope immunoreactivity. These changes were accompanied by increased expression of metalloproteinase MMP13, type X collagen, cellular hypertrophy and loss of proteoglycan at the articular surface. Using a novel micro-mechanical indentation protocol, it was shown that articular cartilage in the humeral head of 4-month-old Fgfr3(-/-) mice was less resistant to compressive force and less stiff than that of littermate controls. These results identify Fgfr3 signaling as a potential target for intervention in degenerative disorders of cartilage metabolism.

Nicotine metabolism and CYP2A6 allele frequencies in Koreans

CYP2A6 is a major catalyst of nicotine metabolism to cotinine. Previously, we demonstrated that the interindividual difference in nicotine metabolism is related to a genetic polymorphism of the CYP2A6 gene in Japanese. To clarify the ethnic differences in nicotine metabolism and frequencies of CYP2A6 alleles, we studied nicotine metabolism and the CYP2A6 genotype in 209 Koreans. The cotinine/nicotine ratio of the plasma concentration 2 h after chewing one piece of nicotine gum was calculated as an index of nicotine metabolism. The genotypes of CYP2A6 gene (CYP2A6*1A, CYP2A6*1B, CYP2A6*2, CYP2A6*3, CYP2A6*4 and CYP2A6*5) were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism or allele specific (AS)-PCR. There were ethnic differences in the allele frequencies of CYP2A6*1A, CYP2A6*1B, CYP2A6*4 and CYP2A6*5 between Koreans (45.7%, 42.8%, 11.0% and 0.5%, respectively) and Japanese (42.4%, 37.5%, 20.1% and 0%, respectively, our previous data). Similar to the Japanese, no CYP2A6*2 and CYP2A6*3 alleles were found in Koreans. The homozygotes of the CYP2A6*4 allele (four subjects) were completely deficient in cotinine formation, being consistent with the data among Japanese. The heterozygotes of CYP2A6*4 tended to possess a lower metabolic ratio (CYP2A6*1A/CYP2A6*4, 4.79 +/- 3.17; CYP2A6*1B/CYP2A6*4, 7.43 +/- 4.97) than that in subjects without the allele (CYP2A6*1A/CYP2A6*1A, 7.42 +/- 6.56; CYP2A6*1A/CYP2A6*1B, 9.85 +/- 16.12; CYP2A6*1B/CYP2A6*1B, 11.33 +/- 9.33). The subjects who possess the CYP2A6*1B allele appeared to show higher capabilities of cotinine formation. It was confirmed that the interindividual difference in nicotine metabolism was closely related to the genetic polymorphism of CYP2A6. The probit plot of the metabolic ratios in Koreans (8.73 +/- 11.88) was shifted to a higher ratio than that in the Japanese (3.78 +/- 3.09). In each genotype group, the Korean subjects revealed significantly higher metabolic ratios than the Japanese subjects. The ethnic difference in cotinine formation might be due to environmental and/or diet factors as well as genetic factors.

[Effect of rare earth elements on the seedling ratio of crops]

The effects of rare earth elements(REEs) on the relative seedling ratio of three crops(rice, rape and soybean) in three soil(red soil, yellow fluvo-aquic soil and yellow cinnamon soil) were studied according to OECD method, and the LC50 were obtained. Toxicity effect of REEs on rice was minimum among the crops tested. The toxicity on crops in yellow cinnamon soil was lower, whereas on soybean in yellow fluvo-aquic soil and on rape in red earth were higher.

Antenatal syphilis in sub-Saharan Africa: missed opportunities for mortality reduction

PURPOSE

Between 4-15% of pregnant women are believed to be infected with syphilis in sub-Saharan Africa. Active infection with syphilis in pregnant women results in foetal or infant death or disability for 50-80% of affected pregnancies, and is a major cause of adult morbidity as well. Antenatal syphilis screening is cheap and effective; however, it is often poorly implemented in countries with high syphilis risk. This study sought to estimate the missed opportunities for antenatal syphilis screening in sub-Saharan Africa.

METHODS

Survey data were collected from 22 ministries of health in sub-Saharan Africa, complemented by data from published sources and key informants. Informants described their country's policies and experience with antenatal syphilis screening and estimated their national syphilis screening rates.

FINDINGS

Seventy-three percent of women are reported by WHO to receive antenatal care in the study countries. Of women in antenatal care, 38% were estimated by survey respondents to be screened for syphilis. Costs and the organization of services were the principal reported obstacles to screening. With syphilis seroprevalence estimated at 8.3%, approximately 1 640 000 pregnant women with syphilis are undetected annually, including 1 030 000 women who attend antenatal care.

DISCUSSION

Syphilis testing and treatment is a cost-effective intervention that deserves much greater attention, particularly in sub-Saharan Africa and other countries where syphilis infection is high.

[Cluster analysis methods appropriate for classification of drought-resistant wheat ecotypes]

The appropriate cluster analysis methods for classification of drought-resistant wheat ecotypes were investigated, based on the analysis of 21 morphologic and agronomic characters of 15 winter wheat cultivars. According to the proximity degree to the results from experts experiences, the cluster results using original data were orderly better than those using Varimax orthogonal rotation, Promax skew intersection rotation, and principal component analysis with phenotypic mean's correlation matrix. The results using Euclidean distance were greater than those using Mahalanobis distance. The clustering methods of correspondent analysis and fuzzy cluster were better than those of nearest distance, furthest distance or group average method (UPGMA). Among all cluster results from various methods combined, the two cluster results from the fuzzy cluster using original data and from the correspondence analysis method were closest to the results of experts' experience. Based on both comparisons of results and examination of the performance of different strategies with several statistical properties, the two methods mentioned above were also acceptable.

The overlapping angB and angG genes are encoded within the trans-acting factor region of the virulence plasmid in Vibrio anguillarum: essential role in siderophore biosynthesis

Products encoded in the trans-acting factor (TAF) region are necessary for the biosynthesis of anguibactin and for maximal expression of iron transport and biosynthesis genes in the plasmid-encoded iron-scavenging system of Vibrio anguillarum. Here we identify angB, a locus located in the TAF region, which encodes products essential for anguibactin biosynthesis. We demonstrate that a 287-amino-acid polypeptide, encoded by angB and designated AngB, has an isochorismate lyase activity necessary for the synthesis of 2, 3-dihydroxybenzoic acid, an anguibactin biosynthesis intermediate. Complementation of various angB mutations provided evidence that an additional, overlapping gene exists at this locus. This second gene, designated angG, also has an essential biosynthetic function. The angG gene directs the expression of three polypeptides when overexpressed in Escherichia coli, all of which are translated in the same frame as AngB. The results of site-directed mutagenesis and in vivo phosphorylation experiments suggest that the carboxy-terminal end of AngB and the AngG polypeptide(s) function as aryl carrier proteins involved in the assembly of the anguibactin molecule. Our results also show that the regulatory functions of the TAF are encoded in a region, TAFr, which is distinct from and independent of the angB and angG genes.

[Protective efficacy of H2 strain live attenuated hepatitis A vaccines in an outbreak of hepatitis A]

OBJECTIVE

To investigate the protective efficacy of H(2) strain live attenuated hepatitis A vaccine (H(2)-strain vaccine) locally produced in an outbreak of hepatitis A (HA).

METHODS

A nonrandomized controlled design was used in a trial for HA vaccination. Five thousand five hundred and fifty-one children at preschool classes and at grades 1 - 3 of primary schools were selected in 14 villages. Epidemiological and serological methods were used to evaluate its protective efficacy of the vaccines and serum immunoglobulin M against hepatitis A virus (IgM anti-HAV) was detected with ELISA for 271 subjects in vaccinated group and 341 in the control one.

RESULTS

An outbreak of HA occurred one year after the vaccination with 26 cases in the vaccinated group, including one vaccine-related case with an attack rate of 0.28% (1/356), and 25 cases in the control group with an attack rate of 5.92% (25/422). The protective efficacy of vaccines was 95.27% (95% confidence interval of 85.83% to 104.72%). Positivity of IgM anti-HAV, i.e., newly-infected cases, was 4.43% (12/271) in the vaccinated group and 13.38% (42/314) in the control group, respectively. Clinically apparent cases accounted for 8.33% (1/12) and 50.00% (21/42) in newly-infected cases in vaccinated and control groups, respectively.

CONCLUSION

Vaccination with H(2) strain vaccines locally produced was effective in reducing occurrence of HA during its outbreak, but not so effective in preventing its infection. A booster dose of HA vaccine should be vaccinated for children in adequate time.

Solution structure of carnobacteriocin B2 and implications for structure-activity relationships among type IIa bacteriocins from lactic acid bacteria

Carnobacteriocin B2 (CbnB2), a type IIa bacteriocin, is a 48 residue antimicrobial peptide from the lactic acid bacterium Carnobacterium pisicola LV17B. Type IIa bacteriocins have a conserved YGNGVXC sequence near the N-terminus and usually contain a disulfide bridge. CbnB2 seemed to be unique in that its two cysteines (Cys9 and Cys14) could be isolated as free thiols [Quadri et al. (1994) J. Biol. Chem. 26, 12204-12211]. To establish the structural consequences of the presence or absence of a disulfide bridge and to investigate if the YGNGVXC sequence is a receptor-binding motif [Fleury et al. (1996) J. Biol. Chem. 271, 14421-14429], the three-dimensional solution structure of CbnB2 was determined by two-dimensional (1)H nuclear magnetic resonance (NMR) techniques. Mass spectroscopic and thiol modification experiments on CbnB2 and on model peptides, in conjunction with activity measurements, were used to verify the redox status of CbnB2. The results show that CbnB2 readily forms a disulfide bond and that this peptide has full antimicrobial activity. NMR results indicate that CbnB2 in trifluoroethanol (TFE) has a well-defined central helical structure (residues 18-39) but a disordered N terminus. Comparison of the CbnB2 structure with the refined solution structure of leucocin A (LeuA), another type IIa bacteriocin, indicates that the central helical structure is conserved between the two peptides despite differences in sequence but that the N-terminal structure (a proposed receptor binding site) is not. This is unexpected because LeuA and CbnB2 exhibit >66% sequence identity in the first 24 residues. This suggests that the N-terminus, which had been proposed [Fleury et al. (1996) J. Biol. Chem. 271, 14421-14429] to be a receptor binding site of type IIa bacteriocins, may not be directly involved and that recognition of the amphiphilic helical portion is the critical feature.

Characterization of the interaction between Fur and the iron transport promoter of the virulence plasmid in Vibrio anguillarum

The expression of iron transport genes fatDCBA in Vibrio anguillarum strain 775 is negatively regulated by two iron-responsive repressors, the Fur protein and the antisense RNA, RNAalpha. Here we report the identification of the promoter for the iron transport genes and studied the interaction between the V. anguillarum Fur protein and this promoter. The iron transport promoter was localized in a region approximately 300 base pairs upstream of fatD by both primer extension and S1 mapping analysis. High activity of the promoter was measured in response to iron depletion in the wild-type strain when a promoter-lacZ fusion was examined, whereas the promoter was constitutive in the Fur-deficient strain. Gel retardation and DNase I footprint analysis showed that Fur binds specifically to two contiguous sites comprising the promoter region and the region downstream of the transcription start site. The identified Fur binding sites showed a low degree of homology to each other as well as to the consensus sequence for the Escherichia coli Fur protein. DNase I footprints pattern suggested a sequential interaction of Fur with these two sites that renders a protection in the template strand and a hypersensitivity to the nuclease in the nontemplate strand. The periodicity of the hypersensitive sites suggested that the promoter DNA undergoes a structural change upon binding to Fur, which might play a role in the repression of gene expression.

IL-15 receptor maintains lymphoid homeostasis by supporting lymphocyte homing and proliferation

The IL-15 receptor alpha subunit (IL-15Ralpha) mediates high-affinity binding of IL-15, a pleiotropic cytokine implicated in the development of innate immune cells. We have generated IL-15Ralpha null (IL-15Ralpha-/-) mice to understand the role of IL-15Ralpha in immune development and function. IL-15Ralpha-/- mice are markedly lymphopenic despite grossly normal T and B lymphocyte development. This lymphopenia is due to decreased proliferation and decreased homing of IL-15Ralpha-/- lymphocytes to peripheral lymph nodes. These mice are also deficient in natural killer cells, natural killer T cells, CD8+ T lymphocytes, and TCRgammadelta intraepithelial lymphocytes. In addition, memory phenotype CD8+ T cells are selectively reduced in number. Thus, IL-15Ralpha has pleiotropic roles in immune development and function, including the positive maintenance of lymphocyte homeostasis.

The complete nucleotide sequence and functional organization of Bacillus subtilis bacteriophage SPP1

The complete nucleotide sequence of the B. subtilis bacteriophage SPP1 is described. The genome is 44,007 bp in size and has a base composition of 43.7% dG + dC. Only 32.2 kb are essential for phage amplification under laboratory conditions. Transcription using only the 'heavy strand' is asymmetric. Eighty-one orfs organized in five early and four late operons were identified. Experiments have shown that 25 orfs are essential. Of the remaining orfs, functions could be predicted for the products of five of the orfs on the basis of comparison of the deduced amino acid sequence to known proteins. Intergenic regions include most of the 5 PE and the 4 PL promoters. Transcripts are polycistronic. Transcription from the PE promoters is mediated by host RP, whereas recognition of the PL promoters requires an additional unidentified phage-encoded product. Translation of mRNA transcribed from most of the orfs seems to be initiated independently, each from its own ribosomal binding and initiation site, although a few cases of coupled translation have been reported. The organization of SPP1 genes involved in the replication, DNA packaging and phage assembly proteins resembles the organization of genes of equivalent regions of different E. coli double-stranded DNA phages. Absence of aa sequence similarity between analogous proteins of different phages suggested that the conserved gene organization is representative of a primordial bacteriophage.

The replisome organizer (G38P) of Bacillus subtilis bacteriophage SPP1 forms specialized nucleoprotein complexes with two discrete distant regions of the SPP1 genome

Initiation of Bacillus subtilis bacteriophage SPP1 DNA replication requires the products of genes 38, 39 and 40 (G38P, G39P and G40P). G38P specifically binds two discrete regions, which are 32.1 kb apart in a linear map of the SPP1 genome. One of these target sites, which maps at the left end of the phage genome, within gene 38, was shown to function as an origin of replication and was therefore termed left origin (oriL). The other site, which lies within a non-coding segment in the late transcribed region on the right end of the genome, was termed oriR. Both sites contain two types of repeated elements (termed Box AB and A + T-rich region). The K(app) for the G38P-oriL DNA and G38P-oriR DNA complexes was estimated to be 1 nM and 4 nM, respectively. G38P binds to the distant oriL and oriR sites cooperatively. DNase I footprinting experiments showed protection by G38P in Box AB, but not in the A + T-rich region. Electron microscopy analysis showed that G38P forms a higher-order nucleoprotein structure with the SPP1 oriL and oriR sites through protein-protein interaction. G38P binding at its cognate sites does not seem to modify the length of the DNA, but to bend it. These results suggest that G38P forms a nucleoprotein complex on the regions where the SPP1 replication origins were previously predicted.

Obstacles to nutrition labeling in restaurants

OBJECTIVE

This study determined the major obstacles that foodservices face regarding nutrition labeling.

DESIGN

Survey questionnaire was conducted in May 1994. In addition to demographic questions, the directors were asked questions addressing willingness, current practices, and perceived obstacles related to nutrition labeling.

SUBJECTS/SETTING

Sixty-eight research and development directors of the largest foodservice corporations as shown in Restaurants & Institutions magazine's list of the top 400 largest foodservices (July 1993).

STATISTICAL ANALYSES PERFORMED

P tests were used to determine significance within a group for the number of foodservices that were currently using nutrition labeling, perceived impact of nutrition labeling on sales, and perceived responsibility to add nutrition labels. Regression analysis was used to determine the importance of factors on willingness to label.

RESULTS

Response rate was 45.3%. Most companies were neutral about their willingness to use nutrition labeling. Two thirds of the respondents were not currently using nutrition labels. Only one third thought that it was the foodservice's responsibility to provide such information. Several companies perceived that nutrition labeling would have a potentially negative effect on annual sales volume. Major obstacles were identified as menu or personnel related, rather than cost related. Menu-related obstacles included too many menu variations, limited space on the menu for labeling, and loss of flexibility in changing the menu. Personnel-related obstacles included difficulty in training employees to implement nutrition labeling, and not enough time for foodservice personnel to implement nutrition labeling.

APPLICATIONS

Numerous opportunities will be created for dietetics professionals in helping foodservices overcome these menu- or personnel-related obstacles.

Bacillus subtilis bacteriophage SPP1 terminase has a dual activity: it is required for the packaging initiation and represses its own synthesis

The B. subtilis bacteriophage SPP1 terminase, encoded by genes 1 and 2, is required for the initiation of headful packaging. The DNA segment to which gene 1 product (G/P) binds includes the pacL and pacR sites and the late PL1 and PL2 promoters from which genes 1 to 7 are transcribed. When SPP1wt or SPP1sus115 (gene 6-) phages were used to infect a B. subtilis sup0 strain, the gene 1 to 7 mRNA synthesis was reduced at late times of infection. This was not observed, however, when either chloramphenicol was added 7 min after infection with SPP1wt or when SPP1sus114 (gene 1-) or SPP1sus19 (gene 2-) were used to infect B. subtilis sup0 cells. These results suggest that the terminase enzyme functions as a repressor of its own transcription. G/P and B. subtilis RNA polymerase (RP) bind to the pacL segment, which contains the PL1 and PL2 promoter region. The binding of G/P to the pacL site does not seem to exclude RP from the promoters, despite of the overlapping of their binding sites. It is likely that the terminase protein does not repress transcription by a mere steric hindrance of RP binding.

Distamycin-induced inhibition of formation of a nucleoprotein complex between the terminase small subunit G1P and the non-encapsidated end (pacL site) of Bacillus subtilis bacteriophage SPP1

The small subunit of the Bacillus subtilis bacteriophage SPP1 terminase (G1P) forms a sequence-specific nucleoprotein complex with the SPP1 non-encapsidated end (pacL site) during initiation of DNA encapsidation. Gel mobility shift assay was used to study the G1P-pacL interaction. Distamycin, a minor groove binder that induces local distortion of the DNA, inhibits G1P-pacL complex formation. The competition of G1P with distamycin for DNA binding at the pacL site is independent of the order of addition of the reactants. Other minor groove binders, such as spermine or Hoechst 33258, which do not distort DNA, failed to compete with G1P for pacL DNA binding. Cationic metals, which generate a repertoire of DNA structures different from that caused by the minor groove binders, can partially reverse the distamycin-induced inhibition of G1P binding to pacL DNA. The major groove binder methyl green, which does not distort sequence-directed bending of pacL DNA, competes with G1P for binding at the pacL site. Our data suggest that the natural sequence-directed bend that exists within the pacL site is the architectural element that facilitates assembly of a nucleoprotein complex and hence initiation of DNA encapsidation by bacteriophage SPP1.

The small subunit of the terminase enzyme of Bacillus subtilis bacteriophage SPP1 forms a specialized nucleoprotein complex with the packaging initiation region

Initiation of SPP1 DNA packaging requires the gene 1 and gene 2 products (G1P and G2P), which are different subunits of the terminase enzyme. G1P specifically recognizes the phage packaging initiation region (pac). The apparent equilibrium constant for the G1P-pac-DNA complex was estimated to be 9 nM. DNase I footprinting experiments reveal that the pac region can be subdivided into three discrete sites (pacL, pacC and pacR). G1P binds co-operatively to the non-adjacent pacL and pacR sites. Several G1P protomers bind to the target sequences which map close to the pac cleavage site (pacC site), but do not overlap with it. G1P interacts in a different fashion with the encapsidated (pacR site) and with the non-encapsidated (pacL site) end of the phage genome. G1P interaction with the intrinsically bent pacL DNA occurs only on one face of the DNA double helix. G1P binding to the pacL and in the pacR region results in a DNA loop. Electron microscopy of purified G1P shows that the protein is an oligomer in solution. G1P binding to the core region of the pacL site could facilitate the formation of a higher-order nucleoprotein structure. This specialized complex would allow the pac DNA to form a loop between binding sites brought together by interaction with G1P. The results presented here suggest that G1P could provide a tool to discriminate the first encapsidated end, which contains pacR, from the non-encapsidated pacL end.

Lead acetate-induced contraction in rabbit mesenteric artery: interaction with calcium and protein kinase C

Animal studies have demonstrated that low-level lead exposure produces hypertension and that lead can cause contraction of vascular smooth muscle directly. The physiological effects of lead have been associated with both stimulation and inhibition of protein kinase C (PKC). Given that vascular smooth muscle contractility is generally enhanced when protein kinase C is activated, we have tested the hypothesis that lead contracts vascular smooth muscle via stimulation of PKC. Helically-cut strips of rabbit mesenteric artery were mounted in muscle baths for measurement of isometric force development. Cumulative addition of lead acetate (10(-10)-10(-3) M) to the muscle bath produced contractions (concentration necessary to produce half-maximal response -log EC50 = 5.16 +/- 0.07). Maximal contraction to lead acetate in arteries denuded of endothelium did not differ from those in intact vessels, supporting the hypothesis that lead-induced contraction is an endothelium-independent event. Contractions to lead acetate were potentiated by the PKC activators, phorbol 12-myristate 13-acetate (TPA; 3 x 10(-7) M) and mezerein (3 x 10(-7) M), as indicated by leftward shifts in the concentration-response curve and increase in the potency of lead (-log EC50 with TPA: 6.94 +/- 0.07; -log EC50 with mezerein: 6.07 +/- 0.04). H-7 (6 x 10(-6) M), an inhibitor of PKC, decreased maximal contraction to lead approximately 65% and slightly, but insignificantly, decreased the potency of lead (-log EC50 = 4.82 +/- 0.1). The inactive phorbol ester, phorbol 12-myristate 13-acetate 4-0-methyl ether (1 x 10(-6) M), did not alter contractile responses to lead (-log EC50 = 4.92 +/- 0.09). Vascular contraction to lead partially depends on extracellular calcium as the L-type voltage-gated calcium channel antagonist, verapamil (3 x 10(-6) M), decreased lead-induced contractions by 50%. These data indicate that lead interacts with PKC in an endothelium-independent, calcium-dependent manner to cause vascular smooth muscle contraction and suggest that lead-induced increases in vascular contractility may play a role in lead-induced hypertension.

M.phi 3TII: a new monospecific DNA (cytosine-C5) methyltransferase with pronounced amino acid sequence similarity to a family of adenine-N6-DNA-methyltransferases

The temperate B.subtilis phages phi 3T and rho 11s code, in addition to the multispecific DNA (cytosine-C5) methyltransferases (C5-MTases) M. phi 3TI and M. rho 11sI, which were previously characterized, for the identical monospecific C5-MTases M. phi 3TII and M. rho 11sII. These enzymes modify the C of TCGA sites, a novel target specificity among C5-MTases. The primary sequence of M. phi 3TII (326 amino acids) shows all conserved motifs typical of the building plan of C5-MTases. The degree of relatedness between M. phi 3TII and all other mono- or multispecific C5-MTases ranges from 30-40% amino acid identity. Particularly M. phi 3TII does not show pronounced similarity to M. phi 3TI indicating that both MTase genes were not generated from one another but were acquired independently by the phage. The amino terminal part of the M. phi 3TII (preceding the variable region 'V'), which predominantly constitutes the catalytic domain of the enzyme, exhibits pronounced sequence similarity to the amino termini of a family of A-N6-MTases, which--like M.TaqI--recognize the general sequence TNNA. This suggests that recently described similarities in the general three dimensional organization of C5- and A-N6-MTases imply divergent evolution of these enzymes originating from a common molecular ancestor.

M.phi 3TII: a new monospecific DNA (cytosine-C5) methyltransferase with pronounced amino acid sequence similarity to a family of adenine-N6-DNA-methyltransferases

The temperate B.subtilis phages phi 3T and rho 11s code, in addition to the multispecific DNA (cytosine-C5) methyltransferases (C5-MTases) M.phi 3TI and M.rho 11sI, which were previously characterized, for the identical monospecific C5-MTases M.phi 3TII and M.rho 11sII. These enzymes modify the C to TCGA sites, a novel target specificity among C5-MTases. The primary sequence of M.phi 3TII (326 amino acids) shows all conserved motifs typical of the building plan of C5-MTases. The degree of relatedness between M.phi 3TII and all other mono- or multispecific C5-MTases ranges from 30-40% amino acid identity. Particularly M.phi 3TII does not show pronounced similarity to M.phi 3TI indicating that both MTase genes were not generated from one another but were acquired independently by the phage. The amino terminal part of the M.phi 3TII (preceding the variable region 'V'), which predominantly constitutes the catalytic domain of the enzyme, exhibits pronounced sequence similarity to the amino termini of a family of A-N6-MTases, which--like M.Taql--recognize the general sequence TNNA. This suggests that recently described similarities in the general three dimensional organization of C5- and A-N6-MTases imply divergent evolution of these enzymes originating from a common molecular ancestor.

Nucleotide sequence and complementation studies of the gene 35 region of the Bacillus subtilis bacteriophage SPP1

Genetic analysis of the Bacillus subtilis bacteriophage SPP1 defective in gene 35 shows that the gene 35 product (G35P) is essential for SPP1 growth. The defect in growth of SPP1tsl17 and SPP1tsl20F at nonpermissive temperature is overcome by wild-type gene 35 expressed from a plasmid. The region where gene 35 maps was cloned and sequenced. Analysis of the nucleotide sequence (5884-bp) around gene 35 revealed 13 open reading frames (orfs). We have assigned the term gene to three of these orfs; gene 35, gene 36, the product of which shares homology with SSB proteins, and gene 38, given the gene order orf 34-orf 34.1-orf 34.2-orf34.3-orf34.4-gene 35-gene 36-orf 36.1-orf 37-orf 37.1-orf 37.2-orf 37.3-gene 38. Gene 35 encodes a protein of 32.0 kDa. By using the T7 promoter-expression system for gene 35 a radioactive band of the expected molecular mass was detected.

Analysis of the Bacillus subtilis bacteriophages SPP1 and SF6 gene 1 product: a protein involved in the initiation of headful packaging

Gene 1 product (G1P) of the related Bacillus subtilis bacteriophages SPP1, SF6, and rho 15 is essential for DNA maturation and packaging. A DNA segment containing gene 1 of phage SF6 or rho 15 origin was cloned and sequenced. SF6 and rho 15 G1P (both with predicted molecular mass of 16.7 kDa) share 71% identity with G1P of SPP1. The G1P of all three phages contains three conserved segments (I, II, and III). Within segments I and II helix-turn-helix DNA binding and nucleotide binding motifs were predicted. G1P of both SPP1 and SF6 origin was purified. SPP1 G1P protein (20.7 kDa), purified from cells overexpressing the cloned gene, purifies together with another polypeptide, having a molecular mass of about 13 kDa. The 13-kDa polypeptide results from a translation start signal within gene 1, and hence was termed SPP1 G1P*. G1P of both SPP1 and SF6 binds specifically to a pac-containing DNA fragment, whereas G1P*, which lacks segment I, does not. Chimeric G1P proteins were obtained by domain swapping between gene 1 of SPP1 and SF6. The results presented here suggest that the G1P DNA binding motif lies in segment I and the major determinant for G1P::G1P interaction might lie in segment II. Segment III and the extended C-terminal part of SPP1 G1P are dispensable. The G1P::G2P interacting region remains uncharacterized.

Analysis of cis and trans acting elements required for the initiation of DNA replication in the Bacillus subtilis bacteriophage SPP1

The development of SPP1 has been studied in several B. subtilis mutants conditionally defective in initiation of DNA replication. Initiation of SPP1 replication is independent of the host DnaA (replisome organizer), DnaB, DnaC and DnaI products, but requires the DnaG (DNA primase) and the DNA gyrase. Furthermore, SPP1 replication is independent of the DnaK (heat shock) protein. The phage-encoded products required for initiation of SPP1 replication have been genetically characterized. Analysis of the nucleotide sequence (3.292 kilobases) of the region where SPP1 initiation replication mutants map, revealed five open reading frames (orf). We have assigned genes 38, 39 and 40 to three of these orfs, which have the successive order gene 38-gene 39-orf39,1-gene 40-orf41. The direction of transcription of the reading frames, the lengths of the mRNAs as well as the transcription start point, upstream of gene 38 (PE2), were identified. Proteins of 29.9, 14.6 and 46.6 kDa were anticipated from translation of gene 38, gene 39 and gene 40, respectively. The purified G38P and G39P have estimated molecular masses of 31 and 15 kDa. G38P and G39P do not share significant identity with primary protein sequences currently available in protein databases, whereas G40P shares substantial homology with a family of DNA primase-associated DNA helicases. G38P binds specifically to two discrete SPP1 DNA restriction fragments (EcoRI-4 and EcoRI-3). The G38P binding site on EcoRI-4 was localized on a 393 bp DNA segment, which lies within the coding sequence of gene 38. The putative binding site on EcoRI-3 was inferred by DNA sequence homology, it maps in a non-coding segment. G39P, which does not bind to DNA, is able to form a complex with G38P. The organization of the SPP1 genes in the gene 38 to gene 40 interval resembles that one found in the replication origin regions of different Escherichia coli double-stranded DNA phages (lambda, phi 80 and P22). We propose that the conserved gene organization is representative of the replication origin region of a primordial phage.

Analysis of the stabilization system of pSM19035-derived plasmid pBT233 in Bacillus subtilis

The low-copy-number, 9.0-kb pSM19035-derived plasmid pBT233, is stably inherited in Bacillus subtilis. The complete nucleotide (nt) sequence of pBT233 has been determined. Analysis of the nt sequence revealed nine major open reading frames (orfs). The repS, erm1 and erm2 genes have been assigned to three of these orfs, and given the gene order, repS-orf alpha-orf beta-orf gamma-orf delta-orf epsilon-orf zeta-erm2-erm1. The organization of genes of the repS-orf gamma region resembles the organization of genes in the repE-orfI region of pAM beta 1. Messenger RNA species of molecular weights corresponding to repS, orf alpha + orf beta, orf gamma, orf delta and orf epsilon + orf zeta were detected by Northern blotting. Proteins of 23.8, 81.3, 34.4, 10.7 and 32.4 kDa correspond to Orfs beta, gamma, delta, epsilon and zeta, respectively. Bands of radioactive proteins of 25, 81, 34, 10 and 32 kDa were detected using the T7 promoter-expression system. The orf beta and orf gamma encode proteins that share homology to site-specific recombinases and type-I topoisomerases, respectively. The orfs, delta, epsilon and zeta, encode proteins with unknown activity. Deletion of a 1.5-kb segment (nt 2999-4552) with coding capacity for orf beta, orf gamma and orf delta does not seem to affect plasmid maintenance. Removal of a 3.0-kb fragment (nt 4598-7689) with coding capacity for orf epsilon and orf zeta reduced plasmid segregational stability, but deletion of a 5.2-kb DNA segment (nt 2546-7826) abolished it.(ABSTRACT TRUNCATED AT 250 WORDS)