Cell density-dependent regulation of mdr-1 gene expression in murine colon cancer cells

We studied the regulation of mdr-1 and P-glycoprotein in sparse and confluent cultures of murine CT-26 colon carcinoma cells. The expression level of mdr-1 mRNA transcripts (analyzed by Northern blot and in situ hybridization) and P-glycoprotein (analyzed by flow cytometry) inversely correlated with cell density. The modulation of mdr gene expression in sparse and confluent cells was not related to cell division, nutrient depletion, inhibition of protein synthesis, gap junction status, extracellular ATP, or the presence of various extracellular matrixes, but may be related to cell-density and cell-contact mediated changes in phosphatase activity. The confluence-mediated downmodulation of mdr-1 increased the chemosensitivity of the cells to several anticancer drugs commonly associated with an in vitro MDR phenotype by increasing the intracellular accumulation of the drugs. These data may explain some of the discrepancies in results obtained when analyzing mdr gene expression in tumors growing in vivo or in vitro, and why mdi expression in tumors is localized to the periphery of the lesions.

CM2 antigen, a potential novel molecule participating in glucuronide transport on rat hepatocyte canalicular membrane

The polarized molecules predominately distributing at hepatocyte canalicular surface play a vital role in disclosing the process of bile formation and etiopathogenisis of cholestatic live diseases. Therefore, it is important to find novel polarized molecules on hepatocyte canalicular membrane. In the present study, canalicular membrane vesicles (CMVs) isolated from rat hepatocyte by density gradient centrifugation were used as immunogens to produce hybridoma and 46 strains of monoclonal antibodies (mAb) against CMVs were obtained. With a series of morphological assay methods, including immunohistochemistry, immunofluorescence and immuno-electron microscope, the antigens recognized by canalicular mAb1 (CM1) and canalicular mAb2 (CM2) were confirmed to predominately distribute at hepatocyte canalicular membrane. Transport activity assay revealed that CM2 could inhibit ATP-dependent E217βG uptake of rat hepatocyte CMVs. Meanwhile, Western blotting analysis showed that the molecular mass of CM2 antigen was approximately 110kDa, which was much less than Mr 180kDa of multidrug resistance-associated protein 2 (MRP2) involved in glucuronide transport. These data indicated that CM2 antigen might be a potential novel molecule participating in glucuronide transport on the hepatocyte canalicular membrane.

MicroRNA-7 functions as an anti-metastatic microRNA in gastric cancer by targeting insulin-like growth factor-1 receptor

Metastasis is a major clinical obstacle in the treatment of gastric cancer (GC) and it accounts for the majority of cancer-related mortality. MicroRNAs have recently emerged as regulators of metastasis by acting on multiple signaling pathways. In this study, we found that miR-7 is significantly downregulated in highly metastatic GC cell lines and metastatic tissues. Both gain-of-function and loss-of-function experiments showed that increased miR-7 expression significantly reduced GC cell migration and invasion, whereas decreased miR-7 expression dramatically enhanced cell migration and invasion. In vivo metastasis assays also demonstrated that overexpression of miR-7 markedly inhibited GC metastasis. Moreover, the insulin-like growth factor-1 receptor (IGF1R) oncogene, which is often mutated or amplified in human cancers and functions as an important regulator of cell growth and tumor invasion, was identified as a direct target of miR-7. Silencing of IGF1R using small interefering RNA (siRNA) recapitulated the anti-metastatic function of miR-7, whereas restoring the IGF1R expression attenuated the function of miR-7 in GC cells. Furthermore, we found that suppression of Snail by miR-7, through targeting IGF1R, increased E-cadherin expression and partially reversed the epithelial-mesenchymal transition (EMT). Finally, analyses of miR-7 and IGF1R levels in human primary GC with matched lymph node metastasis tissue arrays revealed that miR-7 is inversely correlated with IGF1R expression. The present study provides insight into the specific biological behavior of miR-7 in EMT and tumor metastasis. Targeting this novel miR-7/IGF1R/Snail axis would be helpful as a therapeutic approach to block GC metastasis.

Transgastric endoscopic gastroenterostomy using a partially covered occluder: a canine feasibility study

BACKGROUND AND STUDY AIMS

The use of natural orifice transluminal endoscopic surgery (NOTES) for gastroenterostomy has been previously reported, but it remains technically challenging and additional assistance is often needed. The aim of this study was to develop and evaluate a novel method for the creation of a gastroenterostomy using NOTES with an occluder.

METHODS

Transgastric endoscopic gastroenterostomy was performed in 12 healthy female dogs using a therapeutic upper gastrointestinal endoscope and a partially covered occluder. The occluder was removed with a snare 1 week later. The patency of the gastroenterostomy was confirmed by endoscopy, contrast radiological study, necropsy, and histological examination after 2 weeks.

RESULTS

NOTES gastroenterostomy with an occluder was successful in all 12 dogs. The mean operative time was 32.3 ± 10.3 min (range 20.3 - 53.5). One dog (the first; 8.3 %) died 4 days after the operation of severe intra-abdominal infection due to incorrect deployment of the occluder and poor bowel preparation. Minor bleeding occurred at the anastomosis after removal of the occluder in two of the remaining dogs (18.2 %). Necropsy revealed postoperative adhesions that had developed at the anastomotic site in one dog (9.1 %). No anastomotic leakage or intestinal obstruction was observed. Complete healing of the anastomosis was confirmed on histological evaluation.

CONCLUSION

Gastroenterostomy performed entirely by NOTES using an occluder was technically feasible in this survival animal model.

Big roles of microRNAs in tumorigenesis and tumor development

MicroRNAs (miRNAs) are a class of endogenous non-protein-coding small RNAs that are evolutionarily conserved and widely distributed among species. Their major function is to negatively regulate target gene expression. A single miRNA can regulate multiple target genes, indicating that miRNAs may regulate multiple signaling pathways and participate in a variety of physiological and pathological processes. Currently, approximately 50% of identified human miRNA-coding genes are located at tumor-related fragile chromosome regions. Abnormal miRNA expression and/or mutations have been found in almost all types of malignancies. These abnormally expressed miRNAs play roles similar to tumor suppressor genes or oncogenes by regulating the expression and/or function of tumor-related genes. Therefore, miRNAs, miRNA target genes, and the genes regulating miRNAs form a regulatory network with miRNAs in the hub. This network plays a pivotal role in tumorigenesis and tumor development.

Meta-analysis: the significance of screening for JAK2V617F mutation in Budd-Chiari syndrome and portal venous system thrombosis

BACKGROUND

It is important to evaluate whether screening for JAK2V617F mutation should be routinely performed in patients with Budd-Chiari syndrome (BCS) and portal venous system thrombosis (PVST). However, the prevalence of JAK2V617F mutation in such patients is substantially varied, and its association with development of myeloproliferative disorders (MPD) is deficiently identified.

AIMS

To estimate the prevalence of JAK2V617F mutation and to explore the significance of screening for JAK2V617F mutation in these patients.

METHODS

All observational studies regarding the prevalence of JAK2V617F mutation in patients with BCS and PVST were identified via PubMed and MEDLINE databases. Primary items were the proportions of JAK2V617F mutation and MPD.

RESULTS

Twenty-three studies fulfilled the inclusion criteria. Regardless of underlying aetiological factors, the pooled prevalence of JAK2V617F mutation was 37% and 24% in patients with BCS and PVST respectively. After pre-existing MPD was excluded, the pooled prevalence was decreased to 26% and 19%. Heterogeneity among studies was significant for the prevalence of JAK2V617F mutation. Compared with healthy subjects and patients with thrombosis in other sites, the prevalence of JAKV617F mutation was significantly higher in patients with BCS and PVST. The prevalence of MPD was significantly higher in patients with JAK2V617F mutation than those without.

CONCLUSIONS

JAK2V617F mutation is frequently found in patients with BCS and PVST, but there is a huge variation of prevalence among the included studies. Additionally, it is more specific to thrombosis in splanchnic areas and strongly associated with the development of MPD in these patients. Further studies are needed to evaluate whether the screening test should be widely performed in Asian countries and cirrhotic patients.

A reproducible route to p-ZnO films and their application in light-emitting devices

Although great efforts have been made, reproducible p-type doping is still one of the largest hurdles that hinders the optoelectronic applications of ZnO. In this Letter, a reproducible route to p-type ZnO films employing lithium-nitrogen as a dual-acceptor dopant has been demonstrated, and p-i-n structured light-emitting devices (LEDs) have been constructed. Obvious purple emissions have been observed from the LEDs, confirming the applicability of the p-type ZnO films in optoelectronic devices. The results reported in this Letter provide a reproducible route to p-type ZnO films, and thus may lay a solid ground for future optoelectronic applications of ZnO.

Up-regulated expression of Notch1 and Jagged1 in human colon adenocarcinoma

Deregulated expression of Notch molecules is observed in many malignant tumors, however, the expression of Notch1 and Jagged1 in colon adenocarcinoma is still unknown. This study is to investigate the expression of Notch1 and Jagged1 in human colon adenocarcinoma. Sixty-five human colon adenocarcinoma and 60 adjacent nontumor colon tissue sections were detected by immunohistochemistry. Ten paired fresh surgical human colon adenocarcinoma and adjacent nontumor colon samples were analyzed by Western blot and RT-PCR. Both Notch1 and Jagged1 were expressed in the cytoplasm of neoplastic cells of colon adenocarcinoma tissue. The protein and mRNA levels of both molecules were higher in colon adenocarcinoma than in adjacent nontumor tissue. Moreover, Notch1 was positively correlated with tumor stage. This investigation demonstrates that Notch1 and Jagged1 are up-regulated in human colon adenocarcinoma and suggests that Notch1/Jagged1 signaling might play a role in the development of colon adenocarcinoma.

Growth of nanocrystals and thin films at the water-oil interface

The use of the water-oil interface provides significant advantages in the synthesis of inorganic nanostructures. Employing the water-toluene interface, luminescent CdS nanocrystals have been obtained at a relatively modest temperature of 35 degrees C. The diameters of the particulates can be varied between 1.0 and 5.0 nm. In addition, we have devised a new method for transferring thin films at the water-toluene interface onto solid substrates. Using this method, thin films consisting of Au and Ag nanocrystals spread over very large areas (square centimetres) are obtained in a single step. These films are directly usable as ingredients of functional devices. We show this by constructing a working amine sensor based on films of Au nanocrystals. The materials obtained have been characterized by X-ray diffraction, scanning and transmission electron microscopy, absorption and emission spectroscopy and charge transport measurements.

MicroRNA dysregulation in gastric cancer: a new player enters the game

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Recent discoveries have shed new light on the involvement of a class of noncoding RNA known as microRNA (miRNA) in gastric cancer. A substantial number of miRNAs show differential expression in gastric cancer tissues. Genes coding for these miRNAs have been characterized as novel proto-oncogenes and tumor-suppressor genes based on findings that these miRNAs control malignant phenotypes of gastric cancer cells. In this connection, miRNA dysregulation promotes cell-cycle progression, confers resistance to apoptosis, and enhances invasiveness and metastasis. Moreover, certain polymorphisms in miRNA genes are associated with increased risks for atrophic gastritis and gastric cancer, whereas circulating levels of miRNAs may serve as biomarkers for early diagnosis. Several miRNAs have also been shown to correlate with gastric cancer progression, and thus may be used as prognostic markers. Elucidating the biological aspects of miRNA dysregulation may help us better understand the pathogenesis of gastric cancer and promote the development of miRNA-directed therapeutics against this deadly disease.

Meta-analysis: polymorphisms in TNF-alpha gene promoter and Crohn's disease

BACKGROUND

Tumour necrosis factor alpha (TNF-alpha) is involved in the pathogenesis of Crohn's disease (CD). However, results on the association between the polymorphisms in TNF-alpha promoter and the risk of CD are inconsistent.

AIM

To perform a quantitative synthesis for the genetic polymorphisms in TNF-alpha promoter and CD risk.

METHODS

Databases were searched (up to 2009) and 31 studies were included. Risks of CD associated with the polymorphisms in TNF-alpha promoter were assessed.

RESULTS

Overall, individuals with -1031 TC+CC genotype had a slightly increased risk to develop CD compared with individuals with -1031 TT genotype (OR, 1.32; 95% CI, 1.03-1.70). In the further stratified analysis, we found Asians with the -1031T>C, -863 C>A and -857 C>T variant polymorphisms have almost one and a half CD risk compared with other genotypes (OR, 1.58; 95% CI, 1.16-2.15; OR, 1.55; 95% CI, 1.18-2.02; OR, 1.54; 95% CI, 1.19-1.99 respectively). We did not find -308 G>A variant associated with CD location and disease behaviours in stratified analysis.

CONCLUSIONS

TNF-alpha polymorphisms in the promoter region might be used as a biomarker for CD risk prediction. Larger studies with mixed ethnicity subjects and stratified by clinical and sub clinical characteristics are needed to validate our findings.

Apatite reduces amelogenin proteolysis by MMP-20 and KLK4 in vitro

Two enamel proteases, matrix metalloproteinase-20 (MMP-20) and kallikrein 4 (KLK4), are known to cleave amelogenin and are necessary for proper enamel formation. However, the effect of hydroxyapatite (HAP) on the proteolytic activity of these enzymes remains unclear. To investigate whether apatite affects normal amelogenin proteolysis, we used 2 different isoforms of amelogenin combined with the appropriate enzymes to analyze proteolytic processing rates in the presence or absence of synthetic hydroxyapatite (HAP) crystals (N = 3). We found a distinct dose-dependent relationship between the amount of HAP present in the proteolysis mixture and the rate of rP172 degradation by rpMMP-20, whereas the effect of HAP on proteolysis of either rP172 or rP148 by rhKLK4 was less prominent.

Meta-analysis: pre-operative infliximab treatment and short-term post-operative complications in patients with ulcerative colitis

BACKGROUND

Infliximab was approved for use in ulcerative colitis in recent years. It has been debated if infliximab increases the risk of post-operative complications in patients with ulcerative colitis.

AIM

To perform a meta-analysis that examines the relationship between preoperative infliximab treatment and short-term post-operative complications in patients with ulcerative colitis.

METHODS

We searched the PubMed and MEDLINE databases to identify observational studies on the impact of pre-operative infliximab use on short-term post-operative complications in ulcerative colitis. Infectious complications mainly included wound infection, sepsis and abscess, whereas non-infectious complications included intestinal obstruction, thromboembolism and gastrointestinal haemorrhage. Pooled odds ratios (ORs) were calculated for each relationship.

RESULTS

A total of 5 studies and 706 patients were included in our meta-analysis. Overall, we did not find a strong association between pre-operative treatment of infliximab and short-term infectious [OR 2.24, 95% confidence interval (CI) 0.63-7.95] or non-infectious (OR 0.85, 95% CI 0.50-1.45) post-operative complications in ulcerative colitis patients. On the contrary, we discovered that pre-operative infliximab use increased short-term total post-operative complications (OR 1.80, 95% CI 1.12-2.87).

CONCLUSIONS

Pre-operative infliximab use increased the risk of short-term post-operative complications. Subgroup analysis is underpowered to assess the nature of these complications but shows a trend towards increased post-operative infection.

Poly(amidoamine) dendrimer-supported organoplatinum antitumour agents

While numerous water-soluble biocompatible polymers have been utilized for the construction of drug conjugates that offer significant advantages for drug delivery, poly(amidoamine) (PAMAM) dendrimers are superior in many ways for this purpose. They display nanoscale size, uniform shape, excellent water solubility, low toxicity and high surface functionality. In an attempt to circumvent the toxic side effects associated with the administration of organoplatinum drugs, a polymeric prodrug has been prepared from the treatment of a generation 4.5 PAMAM dendrimer with diaquo(1,2-diaminocyclohexane)platinum(II). A well-defined dendrimer–platinum conjugate containing 40 (1,2-diaminocyclohexane)platinum(II) units coordinated to the dendrimer surface via carboxylate groups is formed. This adduct is well behaved, water soluble, contains a high loading of platinum moieties and displays sustained release of active platinum species over a 24 h period under physiological conditions.

Enamel proteases reduce amelogenin-apatite binding

Organic matrix degradation and crystal maturation are extracellular events that occur simultaneously during enamel biomineralization. We hypothesized that enamel proteases control amelogenin-mineral interaction, which, in turn can affect crystal nucleation, organization, and growth. We used a recombinant amelogenin (rP172), a homolog of its major cleavage product (rP148), and a native amelogenin lacking both N- and C-termini (13k). We compared apatite binding affinity between amelogenins and their digest products during proteolysis. We further compared binding affinity among the 3 amelogenins using a Langmuir model for protein adsorption. Amelogenin-apatite binding affinity was progressively reduced with the proteolysis at the C- and N- termini by recombinant pig MMP-20 (rpMMP20) and recombinant human kallikrein-4 (rhKLK4), respectively. The binding affinity of amelogenin to apatite was found to be in the descending order of rP172, rP148, and 13k. Analysis of our data suggests that, before its complete degradation during enamel maturation, stepwise processing of amelogenin by MMP-20 and then KLK4 reduces amelogenin-apatite interaction.

Computer-aided applications of nanoscale smart materials for biomedical applications

Nanotechnology has the potential to impact the treatment of many diseases that currently plague society: cancer, AIDS, dementia of various kinds and so on. Nanoscale smart materials, such as carbon nanotubes, C60, dendrimers and cyclodextrins, hold great promise for use in the development of better diagnostics, drug delivery and the alteration of biological function. Although experimentation is being used to explore the potential offered by these materials, it is by its very nature expensive in terms of time, resources and expertise. Insight with respect to the behavior of these materials in the presence of biological entities can be obtained much more rapidly by molecular dynamics simulation. Furthermore, the results of simulation may be used to guide experimentation so that it is much more productive than it might be in the absence of such information. The interactions of several nanoscale structures with biological macromolecules can already be probed effectively using molecular dynamics simulation. The results obtained should form the basis for significant new developments in the treatment of disease.

Controlled trials in hepatitis B virus-related decompensate liver cirrhosis: peripheral blood monocyte transplant versus granulocyte-colony-stimulating factor mobilization therapy

BACKGROUND

Liver cirrhosis represents the end stage of chronic liver injury. Currently, liver transplantation provides the only definite cure but it is beset with many problems, including lack of donors and risk of rejection. Stem cell therapy is very attractive in this setting because it has the potential to help tissue regeneration. In this study, we aimed to investigate the therapeutic effect of peripheral blood monocyte cell (PBMC) transplantation in decompensated liver cirrhosis.

METHODS

A total of 40 subjects (31 men and nine females, age range 21-71 years) was recruited to two groups. Group 1 received granulocyte-colony-stimulating factor (G-CSF) mobilization, PBMC collection by leukapheresis and PBMC transplant therapy. Group 2 received G-CSF mobilization for 4 days. At baseline and 6 months after treatment, liver function of the two groups was monitored by blood examination and ultrasonagraphy.

RESULTS

Both groups gained significant improvement in liver synthetic function, such as serum albumin and prothrombin time, from baseline to 6 months after treatment (P<0.01). However, there was no significant difference in alanine aminotransferase, aspartate aminotransferase and total bilirubin in both groups (P>0.05). Compared with group 2, a significantly improved liver function was observed in group 1, including elevated serum albumin level and a decreased CTP score (P<0.05). No major adverse effects were noted.

DISCUSSION

Autologous PBMC transplantation could be considered as a novel and alternative treatment for patients with decompensated liver cirrhosis.