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As a kind of abundant and bio-renewable clean energy, it plays an important role in improving the energy structure, protecting the ecological environment, and achieving the sustainable development of the national economy. However, the existing research mainly focuses on the macroscopic aspect, and rarely discusses from the microscopic aspect to evaluate the adsorption capacity of polysilicon on the pair. Here, the specific surface area, total pore tolerance and average pore diameter of micron-level polysiloxane were obtained by low-temperature nitrogen adsorption method. The results showed that the fraction of the enriched sub-quality group, the total pore volume and the average uniformity ratio were better than those of the corresponding vitrin group. The preliminary magnification method was used to study the synthesis of super-crosslinked woven microporous polymer materials at a magnification of 400 times, and problems such as mass and heat transfer during the magnification process were found and improved. It will be used for larger scale and industrial scale in the future. basis. At the same time, a preliminary exploration of the use of a variety of ultra-crosslinked woven microporous polymers for mixed storage experiments has guiding significance for the preparation of convenient woven microporous polymers to improve storage performance. [ABSTRACT FROM AUTHOR]

In order to study the temperature distribution and heat transfer law in the gas hydrate formation and decomposition process, a visualized experimental system is used to study the reaction heat of methane hydrate formation process and the temperature distribution in the methane hydration in the two systems. Based on the experimental data and the equation for reaction heat calculation, the reaction heat in the two experimental systems is calculated, the effect of the addition of non-ionic surfactant sorbitan stearate (Span 60) on the methane hydration reaction system temperature field is studied. The results show that the addition of Span 60 can contribute to the increase both in the number of methane hydrates and in the quantity of corresponding reaction heat, thereby increasing the temperature of the hydration reaction system and the rising rate of temperature. On the basis of analysis on the Span 60 molecular structure, its mechanism of action has been studied. The process and matters needing attention of measuring the morphology and change characteristics of methane hydrate particles by cryogenic scanning electron microscope are described. [ABSTRACT FROM AUTHOR]

Background: Pentraxins are a family of highly conserved secreted proteins that regulate the innate immune system, including monocytes and macrophages. C-reactive protein (CRP) is a plasma protein whose levels can rise to 1000 µg/ml from the normal <3 µg/ml during inflammation. Results: We find that CRP inhibits proliferation of the human myeloid leukemia cell line Mono Mac 6 with an IC50 of 75 µg/ml by inducing apoptosis of these cells. The related proteins serum amyloid P (SAP) and pentraxin 3 (PTX3) do not inhibit Mono Mac 6 proliferation. CRP has no significant effect on the proliferation of other leukemia cell lines such as HL-60, Mono Mac 1, K562, U937, or THP-1, or the survival of normal peripheral blood cells. The effect of CRP appears to be dependent on the CRP receptor FcγRI, and is negatively regulated by a phosphatidylinositol-3-kinase pathway. Conclusion: These data reveal differential signaling by pentraxins on immune cells, and suggest that CRP can regulate the proliferation of some myeloid leukemia cells. [ABSTRACT FROM AUTHOR]

Preservatives are a major component of the ophthalmic preparations in multi-dose bottles. The purpose of this study was to investigate the acute effect of benzalkonium chloride (BAC), a common preservative used in ophthalmic preparations, on the localization and expression of zonula occludens (ZO)-1 in the rabbit corneal epithelium in vivo. BAC at 0.005%, 0.01%, or 0.02% was topically applied to one eye each of albino rabbits at 5 min intervals for a total of 3 times. The contralateral untreated eyes served as controls. The following clinical indications were evaluated: Schirmer test, tear break-up time (BUT), fluorescein and rose Bengal staining. The structure of central cornea was examined by in vivo confocal microscopy, and the corneal barrier function was evaluated by measurement of corneal transepithelial electrical resistance and permeability to carboxy fluorescein. Whole mount corneas were analyzed by using fluorescence confocal microscopy for the presence of ZO-1, 2, occludin, claudin-1, Ki67 and cell apoptosis in the epithelium. The expression of ZO-1 in the corneal epithelium was also examined by western blot and reverse transcription-polymerase chain reaction analyses. Exposure to BAC resulted in higher rose Bengal staining scores while no significant changes in BUT, Schirmer and corneal florescein scores. It also induced corneal epithelial cell damage, dispersion of ZO-1 and ZO-2 from their normal locus at the superficial layer and disruption of epithelial barrier function. However, the amounts of ZO-1 mRNA and protein in the corneal epithelium were not affected by BAC treatment. Exposure to BAC can quickly impair the corneal epithelium without tear deficiency. BAC disrupts the tight junctions of corneal epithelium between superficial cells in the rabbit corneal epithelium in vivo. [ABSTRACT FROM AUTHOR]

Benzalkonium chloride (BAC) is the most common preservative in ophthalmic preparations. Here, we investigated the corneal alternations in rabbits following exposure to BAC. Twenty-four adult male New Zealand albino rabbits were randomly divided into three groups. BAC at 0.01%, 0.05%, or 0.1% was applied twice daily to one eye each of rabbits for 4 days. The contralateral untreated eyes were used as control. Aqueous tear production and fluorescein staining scores of BAC-treated eyes were compared with those of controls. The structure of the central cornea was examined by in vivo confocal microscopy. Expression of mucin-5 subtype AC (MUC5AC) in conjunctiva was detected by immunostainig on cryosections. Corneal barrier function was assessed in terms of permeability to carboxy fluorescein (CF). The distribution and expression of ZO-1, a known marker of tight junction, and reorganization of the perijunctional actomyosin ring (PAMR) were examined by immunofluorescence analysis. Although there were no significant differences between control and BAC-treated eyes in Schirmer scores, corneal fluorescein scores and the number of conjunctival MUC5AC staining cells, in vivo confocal microscopy revealed significant epithelial and stromal defects in all BAC-treated corneas. Moreover, BAC at 0.1% resulted in significant increases in central corneal thickness and endothelial CF permeability, compared with those in control eyes, and endothelial cell damage with dislocation of ZO-1 and disruption of PAMR. Topical application of BAC can quickly impair the whole cornea without occurrence of dry eye. A high concentration of BAC breaks down the barrier integrity of corneal endothelium, concomitant with the disruption of PAMR and remodeling of apical junctional complex in vivo. [ABSTRACT FROM AUTHOR]

Vascular resistance and blood pressure (BP) are reduced during late normal pregnancy (Norm-Preg). In contrast, studies in human preeclampsia and in animal models of hypertension in pregnancy (HTN-Preg) have suggested that localized reduction in uterine perfusion pressure (RUPP) in late pregnancy is associated with increased systemic vascular resistance and BP; however, the vascular mechanisms involved are unclear. Because Ca2+ is a major determinant of vascular contraction, we hypothesized that the intracellular free calcium concentration ([Ca2+]i) signaling of vasoconstriction is differentially regulated in systemic microvessels during normal and RUPP in late pregnancy. Pressurized mesenteric microvessels from Norm-Preg and RUPP rats were loaded with fura 2 in preparation for simultaneous measurement of diameter and [Ca2+]i (presented as fura 2 340/380 ratio). Basal [Ca2+]i was lower in RUPP (0.73 ± 0.03) compared with Norm-Preg rats (0.82 ± 0.03). Membrane depolarization by 96 mM KC1, phenylephrine (Phe, 10-5 M), angiotensin II (ANG II, 10-7 M), or endothelin-1 (ET-1, 10-7 M) caused an initial peak followed by maintained vasoconstriction and [Ca2+]i. KC1 caused similar peak vasoconstriction and [Ca2+]i in Norm-Preg (45.5 ± 3.3 and 0.89 ± 0.02%) and RUPP rats (46.3 ± 2.1 and 0.87 ± 0.01%). Maximum vasoconstriction to Phe, ANG II, and ET- 1 was not significantly different between Norm-Preg (28.6 ± 4.8, 32.5 ± 6.3, and 40 ± 4.6%, respectively) and RUPP rats (27.8 ± 5.9, 34.4 ± 4.3, and 38.8 ± 4.1%, respectively). In contrast, the initial Phe-, ANG II-, and ET-1-induced 340/380 ratio ([Ca2+]i) was reduced in RUPP (0.83 ± 0.02, 0.82 ± 0.02, and 0.83 ± 0.03, respectively) compared with Norm-Preg rats (0.95 ± 0.04, 0.93 ± 0.01, and 0.92 ± 0.02, respectively). Also, the [Ca2+]i-vasoconstriction relationship was similar in KCI-treated but shifted to the left in Phe-, ANG II-, and ET-1-treated microvessels of RUPP compared with Norm-Preg rats. The lower agonist-induced [Ca2+]i signal of vasoconstriction and the leftward shift in the [Ca2+]i-vasoconstriction relationship in mi- crovessels of RUPP compared with Norm-Preg rats suggest activation of [Ca2+]i sensitization pathway(s). The similarity in vasoconstriction in RUPP and Norm-Preg rats suggests that such a [Ca2+]i sensitization pathway(s) may also provide a feedback effect on Ca2+ mobilization/homeostatic mechanisms to protect against excessive vasoconstriction in systemic microvessels during RUPP in late pregnancy. [ABSTRACT FROM AUTHOR]

Multidrug resistance-associated protein MRP3/Mrp3 (ABCC3) is upregulated in cholestasis, an adaptive response that may protect the liver from accumulation of toxic compounds, such as bile salts and bilirubin conjugates. However, the mechanism of this upregulation is poorly understood. We and others have previously reported that fetoprotein transcription factor/liver receptor homolog-1 is an activator of MRP3/Mrp3 expression. In searching for additional regulatory elements in the human MRP3 promoter, we have now identified nuclear receptor retinoic X receptor-α:retinoic acid receptor-α (RXRα:RARα) as a repressor of MRP3 activation by transcription factor Sp1. A luciferase reporter assay demonstrated that cotransfection of transcription factor Spl stimulates the MRP3 promoter activity and that additions of RXRα:RARα abrogated this activation in a dose-dependent manner. Site mutations and gel shift assays have identified a Sp1 binding GC box motif at - 113 to - 108 nts upstream from the MRP3 translation start site, where RXRα:RARα specifically reduced Sp1 binding to this site. Mutation of the GC box also reduced MRP3 promoter activity. The functional role of RXRα:RARα as a repressor of MRP3 expression was further confirmed by RARα small-interfering RNA knockdown in HepG2 cells, which upregulated endogenous MRP3 expression. In summary, our results indicate that activator Sp1 and repressor RXRα:RARα act in concert to regulate MRP3 expression. Since RXRα:RARα expression is diminished by cholestatic liver injury, loss of RXRα:RARα may lead to upregulation of MRP3/Mrp3 expression in these disorders. [ABSTRACT FROM AUTHOR]

Linear chains of five to hundreds of phosphates called polyphosphate are found in organisms ranging from bacteria to humans, but their function is poorly understood. In Dictyostelium discoideum, polyphosphate is used as a secreted signal that inhibits cytokinesis in an autocrine negative feedback loop. To elucidate howcells respond to this unusual signal, we undertook a proteomic analysis of cells treated with physiological levels of polyphosphate and observed that polyphosphate causes cells to decrease levels of actin cytoskeleton proteins, possibly explaining how polyphosphate inhibits cytokinesis. Polyphosphate also causes proteasome protein levels to decrease, and in both Dictyostelium and human leukemia cells, decreases proteasome activity and cell proliferation. Polyphosphate also induces Dictyostelium cells to begin development by increasing expression of the cell-cell adhesion molecule CsA (also known as CsaA) and causing aggregation, and this effect, as well as the inhibition of proteasome activity, is mediated by Ras and Akt proteins. Surprisingly, Ras and Akt do not affect the ability of polyphosphate to inhibit proliferation, suggesting that a branching pathway mediates the effects of polyphosphate, with one branch affecting proliferation, and the other branch affecting development. [ABSTRACT FROM AUTHOR]

Background/Aims: The transjugular intrahepatic portosystemic shunt (TIPS) is technically divided into TIPS through the left branch of the portal vein (TIPS-LBPV) and TIPS through the right branch of the portal vein (TIPS-RBPV). In order to compare their advantages and disadvantages, this randomized, controlled trial was designed to investigate their outcomes in advanced cirrhotic patients. Methods: Seventy-two patients were randomly placed into TIPS-LBPV (36 patients) and TIPS-RBPV (36 patients, with four failures) groups, and they were prospectively followed for 2 years after TIPS implantation. Results: Patients who underwent the two different kinds of TIPS were balanced during recruitment for this study. The incidences of overall encephalopathy and de novo encephalopathy in the TIPS-LBPV group were significantly lower than that of the TIPS-RBPV group during follow-up ( P=0.036 and 0.012 respectively). The incidences of rebleeding or re-intervention and improvement of ascites were similar between groups ( P>0.05). Patients undergoing TIPS-RBPV required more rehospitalization and incurred more costs than those who underwent TIPS-LBPV ( P=0.030 and 0.039 respectively). There was no significant difference between the two groups in survival based on a survival curve constructed according to the Kaplan–Meier method ( P>0.05). Conclusion: Patients undergoing TIPS-LBPV had a lower incidence of encephalopathy, less rehospitalization and lower costs after TIPS implantation compared with patients undergoing TIPS-RBPV. [ABSTRACT FROM AUTHOR]

Background: To assess the correlation of H. pylori infection with mitochondrial microsatellite instability (mtMSI) and IL-8 in gastric carcinogenesis. Methods: H. pylori infection was evaluated through histology and a urease breath test; mtMSI was measured using PCR-single strand conformation polymorphism (PCR-SSCP); IL-8 was analyzed with ELISA methods. Results: The detection rate of mtMSI was significantly higher in specimens with H. pylori infection than in those without H. pylori infection (P < 0.05). The levels of IL-8 were significantly higher in specimens with mtMSI than in those without mtMSI (P < 0.01 ). An association of mtMSI with the intestinal histological type was found (P< 0.05). Increased IL-8 levels induced by H. pylori were related to the invasion, lymphnode spreading and clinical stage of gastric cancer (P < 0.05). Conclusions: H. pylori infection is related to mitochondrial microsatellite instability in the early steps of gastric cancer development. IL-8 may play a role in the development of mtMSI induced by H. pylori. Our results support a role for mtMSI in different mechanisms of gastric carcinogenesis. [ABSTRACT FROM AUTHOR]

Background: How host cell glycosylation affects EPEC or EHEC O157:H7 invasion is unclear. This study investigated whether and how O-glycans were involved in EPEC or EHEC O157:H7 invasion into HT-29 cells. Results: Lectin histochemical staining confirmed stronger staining with PNA, which labeled Galβ1, 3 GalNAc (core 1 structure) in HT-29-Gal-OBN and C2GnT2-sh2/HT-29 cells, compared with control cells. EPEC or EHEC O157:H7 invasion into HT-29 and its derived cells was based on the intracellular presence of GFP-labeled bacteria. The differentiation of HT-29 cells led to a reduction in EPEC internalization compared with HT-29 cells (p < 0.01). EPEC or EHEC O157:H7 invasion into HT-29-OBN and HT-29-Gal-OBN cells increased compared with HT-29 and HT-29-Gal cells (p < 0.05 and p < 0.01). Core 2 O-glycan-deficient HT-29 cells underwent a significant increase in EPEC (p < 0.01) or EHEC O157:H7 (p < 0.05) invasion compared with control cells. Methods: Bacterial invasion into cultured cells was determined by a gentamicin protection assay and a GFP-labeled bacteria invasion assay. O-glycans biosynthesis was inhibited by benzyl-a-GalNAc, and core 2 O-glycan-deficient HT-29 cells were induced by C2GnT2 interference. Conclusion: These data indicated that EPEC or EHEC O157:H7 invasion into HT-29 cells was related to their O-glycosylation status. This study provided the first evidence of carbohydrate-dependent EPEC or EHEC O157:H7 invasion into host cells. [ABSTRACT FROM AUTHOR]

We successfully treated a patient who was diagnosed of having hypertrophic obstructive cardiomyopathy after the aortic valve replacement surgery for the concomitant aortic stenosis. We report this first in kind new procedure exclusively developed in our center, Liwen procedure™ (percutaneous intramyocardial septal radiofrequency ablation), for patients with left ventricular outflow tract obstruction in spite of maximal medical therapy. The procedure was performed under transthoracic echo guidance. We discussed the technical details, safety, and effectiveness with corresponding images. The patient did well one year after the procedure without LVOT obstruction or arrhythmia. [ABSTRACT FROM AUTHOR]

Ascl2, a basic helix-loop-helix transcription factor, is a downstream target of WNT signaling that controls the fate of intestinal cryptic stem cells and colon cancer progenitor cells. However, its involvement in colon cancer and downstream molecular events is largely undefined; in particular, the mechanism by which Ascl2 regulates the plasticity of epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) programs in colon cancer cells remains unknown. In this study, we systematically demonstrate that Ascl2 loss of function in colon cancer cells promotes MET by derepressing the expression of microRNA (miR)-200s (i.e. miR-200b, miR- 200a, miR-429, miR-200c, and miR-141) and further activating their expression through a transcriptional mechanism that involves direct binding to the most proximal E-box (E-box2) in the miR-200b-a-429 promoter. Activation of miR-200s due to Ascl2 deficiency led to the inhibition of ZEB1/2 expression and the alteration of epithelial and mesenchymal features. Transfection of miR-200b, miR-200a, and miR-429 inhibitors into Ascl2- deficient colon cancer cells promoted the epithelial-mesenchymal transition in a reversible manner. Transfection of miR-200a or miR-429 inhibitors into Ascl2-deficient colon cancer cells increased cellular proliferation and migration. Ascl2mRNAlevels and the miR-200a, miR-200b, miR-200c, miR-141, or miR- 429 levels in the colon cancerous samples were inversely correlated. These results provide the first evidence of a link between Ascl2 and miR-200s in the regulation of EMT-MET plasticity in colon cancer. [ABSTRACT FROM AUTHOR]

We investigated whether a synthetic tetrameric branched peptide based on the conserved TFLK motif from mammaryassociated serum amyloid A3 (M-SAA3) is more efficient than the monomeric peptide at up-regulating MUC3 expression and examined the possible mechanism(s) and biological significance of this process. We used standard solid-phase methods to synthesize a tetrameric branched peptide (sequence GWLTFLKAAG) containing a trilysine core, termed the TFLK-containing 10-mer BP. The aberrant expression of transcription factors was analyzed using a transcription factor protein/DNA array.MUC3 and relevant transcription factors were detected using real-time PCR and/or Western blots. The luciferase assay, EMSA, and ChIP assays were used to analyze the activity of the human MUC3 promoter. The bacterial adherence assay was used to evaluate the in vitro inhibition of enteropathogenic Escherichia coli or enterohemorrhage E. coli serotype O157:H7 (EHEC O157:H7) adherence to HT-29-Gal cells after treatment with the TFLK-containing 10-mer BP. In HT-29-Gal cells, the TFLKcontaining 10-mer BP induced higher levels of MUC3 expression than the M-SAA3-derived N-terminal 10-mer monomeric peptide, andMUC3expression was activated through transcriptional mechanisms, including the induction of multiple transcription factors and further binding with their cis-elements between nucleotides -242 and -62 within MUC3 promoter. Interestingly, the TFLK-containing 10-mer BP dramatically inhibited enteropathogenic E. coli and EHEC O157:H7 adherence to the HT-29-Gal cells compared with the controls. This finding suggests a potential therapeutic use for this peptide to prevent gastrointestinal infection. [ABSTRACT FROM AUTHOR]

Background: Achaete scute-like 2 (Ascl2), a basic helix-loop-helix (bHLH) transcription factor, controls the fate of intestinal stem cells. However, the role of Ascl2 in colon cancer progenitor cells remains unknown. The cell line HT-29 (47.5-95% of CD133+ population) and LS174T (0.45% of CD133+ population) were chosen for functional evaluation of Ascl2 in colon cancer progenitor cells after gene knockdown by RNA interference. Methodology/Principal Findings: Immunohistochemistry demonstrated that Ascl2 was significantly increased in colorectal adenocarcinomas. Downregulation of Ascl2 using RNA interference in cultured colonic adenocarcinoma HT-29 and LS174T cells reduced cellular proliferation, colony-forming ability, invasion and migration in vitro, and resulted in the growth arrest of tumor xenografts in vivo. The Ascl2 protein level in CD133+ HT-29 cells was significantly higher than in CD1332 HT-29 cells. Ascl2 blockade via shRNA interference in HT-29 cells (shRNA-Ascl2/HT-29 cells) resulted in 26.2% of cells staining CD133+ compared with 54.7% in control shRNA-Ctr/HT-29 cells. The levels of 'stemness' associated genes, such as CD133, Sox2, Oct4, Lgr5, Bmi1, and C-myc, were significantly decreased in shRNA-Ascl2/HT-29 and shRNA-Ascl2/LS174T cells in vitro as well as in the corresponding tumor xenograft (CD133 was not performed in shRNA-Ascl2/LS174T cells). The shRNA-Ascl2/ HT-29 cells had inhibited abilities to form tumorspheres compared with control. The microRNA (miRNAs) microarrays, identified 26 up-regulated miRNAs and 58 down-regulated miRNAs in shRNA-Ascl2/HT-29 cells. Expression levels of let-7b, miRNA-124, miRNA-125b, miRNA-17, miRNA-20a and miRNA-302b, involved in the regulation of 'stemness', were quantified with qPCR, which confirmed their identities. Restoration of miRNA-302b, via its mimic, led to the restoration of shRNA-Ascl2/ HT-29 'stemness' characteristics, including tumorsphere formation and 'stemness' associated genes levels, and the recovery of cellular behaviors, including colony-forming ability, invasion and migration in vitro. Conclusions/Significance: Ascl2 may be a potential target for the inhibition of colon cancer progenitor cells, and functions through a miR-302b-related mechanism. [ABSTRACT FROM AUTHOR]

Background: The secreted proteins from goblet cells compose the intestinal mucus. The aims of this study were to determine how they exist in two intestinal mucus layers. Methodology/Principal Findings: The intestinal mucosa was fixed with Carnoy solution and immunostained. Mucus from the loose layer, the firm layer was gently suctioned or scraped, respectively, lysed in SDS sample buffer with or without DTT, then subjected to the western blotting of rTFF3, rIgGFccBP or rMuc2. The non-reduced or reduced soluble mucus samples in RIPA buffer were co-immunoprecipitated to investigate their possible interactions. Polyclonal antibodies for rTFF3, the rIgGFccBP C-terminal domain and the rMuc2 C-terminal domain confirmed their localization in the mucus layer and in the mucus collected from the rat intestinal loose layer or firm layer in both western blot and immunoprecipitation experiments. A complex of rTFF3, which was approximately 250 kDa, and a monomer of 6 kDa were present in both layers of the intestinal mucus; rIgGFccBP was present in the complex (250-280 kDa) under non-reducing conditions, but shifted to 164 kDa under reducing conditions in both of the layers. rMuc2 was found mainly in a complex of 214-270 kDa under nonreducing conditions, but it shifted to 140 kDa under reducing conditions. The co-immunoprecipitation experiments showed that binding occurs among rTFF3, rIgGFccBP and rMuc2 in the RIPA buffer soluble intestinal mucus. Blocking the covalent interaction by 100 mM DTT in the RIPA buffer soluble intestinal mucus disassociated their binding. Conclusions/Significance: Rat goblet cell-secreted TFF3, IgGFccBP and Muc2, existing in the two intestinal mucus layers, are bound together by covalent interactions in the soluble fraction of intestinal mucus and form heteropolymers to be one of the biochemical mechanisms of composing the net-like structure of mucus. [ABSTRACT FROM AUTHOR]

Background: SOX2 and Hath1 are transcription factors that are critical for the control of terminal cell differentiation in the gastrointestinal mucosa. This study investigated the correlations between SOX2 and Hath1 expression in gastric carcinoma and patients' clinicopathological features and prognosis.Methods: Hath1 and SOX2 were detected by immunohistochemistry in gastric carcinoma (n = 50). Probability of survival of patients after surgery was estimated by the Kaplan-Meier method and compared using Log-rank test.Results: Hath1 and SOX2 were inversely expressed in gastric carcinoma. Patients with strong SOX2 expression (++ to +++) showed lower incidences of lymph node metastasis (p = 0.007), deeper invasion (p = 0.010), and III-IV clinical stages (p = 0.011) compared to patients with low SOX2 expression (- to +). There was no significant difference in SOX2 and Hath1 expression in the cancerous tissues of the patients with and without Helicobacter pylori infection (p > 0.05). The patients with strong expression of SOX2 in their cancerous tissues (++ to +++) had a better prognosis than those with low expression of SOX2 (- to +; p = 0.005). There was no correlation between Hath1 expression level and prognosis (p = 0.676).Conclusions: SOX2 and Hath1 are inversely expressed in gastric carcinoma. SOX2 provides a survival advantage to patients of gastric carcinoma and appears to be associated with metastasis and clinical stages. [ABSTRACT FROM AUTHOR]

Background: Pregnane xenobiotic receptor (PXR), a ligand-activated transcription factor, regulates the drug metabolism and transport. Its activation can reduce the efficacy of antineoplastic agents. The aim of this study was to investigate the role of PXR and the relationship between PXR and multidrug resistance-related protein 3 (MRP3) in human colon cancer chemoresistance.Results: The results showed that both the mitochondrial RNA (mRNA) and protein levels of PXR and MRP3 were much higher in colon cancer tissues than that in nonneoplastic tissues by reverse transcriptase polymerase chain reaction and Western blot analysis. MRP3 mRNA was significantly correlated with PXR mRNA in cancerous (P = 0.001) and nonneoplastic (P < 0.001) colon tissues with Pearson correlation test. The expressions of PXR, SP1, and MRP3 were markedly enhanced after rifampicin treatment. On the other hand, the protein level of MRP3 decreased after stable RNA interference of PXR. It also observed that PXR, activated by rifampicin or knocked down via short hairpin RNAs, could enhance or reduce cells resistance to the chemotherapeutic agents through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.Conclusions: The results suggested that PXR, associated with MRP3, may play an important role in human colon cancer resistance to chemotherapeutics and SP1 may be involved in the induction of MRP3 by PXR activation. [ABSTRACT FROM AUTHOR]

A prominent feature of the rodent Muc3 SEA module is the precursor cleavage event that segregates the O-glycosylated N-terminal fragment and transmembrane domain into the noncovalently attached heterodimer. There are seven potential N-glycosylation sites that occur in a cluster in the SEA module of Muc3. However, it is unknown if these sites are modified or what the function of these N-glycans may be in the SEA module. Our data show that the proteolytic cleavage of the rodent Muc3 SEA module was partially prevented by treatment with tunicamycin, an inhibitor of N-glycosylation. Each single mutant of the seven N-glycosylation sites (N1A, N2A, N3A, N4A, N5A, N6A, and N7A) and multiple mutants, including double (N34A) and triple (N345A) mutants, and mutants with four (N3457A), five (N34567A), six (N134567A and N234567A), seven (N1234567A) mutations, confirmed that all seven of these potential sites are N-glycosylated simultaneously. The proteolytic cleavage of the SEA module was not affected when it lacked only one, two, or three N-glycans, but was partially inhibited when lacking four, five, and six N-glycans. In all, 2%, 48%, 85%, and 73% of the products from N3457A, N34567A, N134567A, and N234567A transfectants, respectively, remained uncleaved. The proteolytic cleavage was completely prevented in the N1234567A transfectant, which eliminated all seven N-glycans in the SEA module. The interaction of the heterodimer was independent of the N-glycans within the rodent Muc3 SEA module. Thus, the N-glycosylation pattern constituted a control point for the modulation of the proteolytic cleavage of the SEA module. [ABSTRACT FROM PUBLISHER]