Expression and localisation of claudin-1, -2, -3, -4, -5, -7 and -10 proteins in the normal canine mammary gland

The recently identified claudins are dominant components of tight junctions, responsible for cell adhesion, polarity and paracellular permeability. Certain claudins have been shown to have relevance in tumour development. The aim of the present study was to analyse the expression of claudin-1, -2, -3, -4, -5, -7 and -10 in normal canine mammary glands. Samples from the inguinal mammary regions of 20 non-castrated, 1-13 years old female dogs were studied. Immunohistochemical analysis was performed on conventional specimens and tissue microarrays. The results of the immunohistochemical reactions detecting claudins in tissue sections were photodocumented. The immunoreactivity of claudins was quantitatively analysed on digital images using Leica QWin morphometry software. Intense membranous immunolabelling was found for claudin-1, -3 and -7, intense membranous with non-granular cytoplasmic immunolabelling for claudin-2, moderate membranous immunolabelling for claudin-4 and -5, and weak membranous immunolabelling for claudin-10. The occurrence of tight junctions was confirmed by ultrathin section electron microscopy. The available data suggested that claudins might be proteins preserved throughout the evolution of mammals. The results of our study support the concept that they are indeed preserved, since the same type of claudins, in identical distribution, could be detected in our canine mammary tissue samples as could be found in human mammary tissue.

Comparison of the expression of agrin, a basement membrane heparan sulfate proteoglycan, in cholangiocarcinoma and hepatocellular carcinoma

Heparan sulfate proteoglycans mediate cell adhesion and control the activities of numerous growth and motility factors. They play a critical role in carcinogenesis and tumor progression. Agrin is a large multidomain heparan sulfate proteoglycan associated with basement membranes in several tissues. The expression of agrin in the liver has recently been described under physiologic and pathologic conditions. However, little is known about its role in malignancies. We aimed to study the mRNA and protein expression of agrin in cholangiocarcinoma (CC) and focused on the differences between CC and hepatocellular carcinoma (HCC). Eighty surgically removed liver specimens were studied by immunohistochemistry. Representative samples were used for immunoblotting. mRNA expression was measured in 32 samples by real-time polymerase chain reaction. By immunohistochemistry, agrin was seen around bile ducts and blood vessels within the portal areas in the normal liver. Although no expression was found within the hepatic lobules, agrin was deposited in the neovascular basement membrane in HCCs. Agrin was abundant in the tumor-specific basement membrane in well-differentiated areas of CCs, whereas with immunostaining, it was fragmented, decreased, or it even disappeared in less differentiated areas and sites of infiltration. By real-time polymerase chain reaction, up-regulation of agrin expression was measured in HCCs compared with that in the normal liver. CC samples showed an even higher expression of agrin. Immunoblotting confirmed these findings. Our results indicate that agrin might play an important role in neoangiogenesis in human HCC, being a part of the newly formed vasculature. In CC, however, agrin might be involved in tumor progression.

Short-term alanyl-glutamine dipeptide pretreatment in liver ischemia–reperfusion model: Effects on microcirculation and antioxidant status in rats

BACKGROUND & AIMS

Ischemia-reperfusion (I-R) injury is responsible for the morbidity associated with liver surgery. Production of toxic free radicals influences the microcirculation. The aim of our study was to examine the effect of glutamine (Gln) supplementation--adminstered in alanyl-glutamine dipeptide form--on liver function, immuno/histopathology and the oxidative state of the liver after injury.

METHODS

Two-hundred and fifty grams male Wistar rats underwent normothermic, 60 min, segmental liver ischemia followed by 6 h of reperfusion. The animals (n = 45) were divided into three groups: sham operated, I-R and parenteral Gln pretreatment. Hepatic microcirculation was monitored by laser Doppler flowmetry. At the 6 h of reperfusion, histological alterations, TUNEL reaction, active caspase-3 reaction, serum and liver tissue antioxidant levels, serum ALAT, ASAT and TNF-alpha levels were measured.

RESULTS

Upon reperfusion, the Gln group had significantly (p<0.05) higher flow rates than the I-R group and, at the end of the 6h of reperfusion, significantly (p<0.05) lower serum ALAT and ASAT levels. The liver chemiluminescent intensity was lower, free SH-groups were elevated, while the reducing power was decreased in the Gln-pretreated group. Positive staining for caspase-3 after Gln pretreatment was significantly increased in contrast to the control tissues.

CONCLUSION

Glutamine pretreatment is beneficial in supporting hepatic microcirculation and can prevent hepatocellular necrosis in liver reperfusion injury.

Effect of PJ-34 PARP-Inhibitor on Rat Liver Microcirculation and Antioxidant Status

BACKGROUND

Ischemia-reperfusion (I-R) injury during liver resection leads to the production of toxic free radicals and oxidants that influence the microcirculation. DNA single-strand breaks can be induced by these reactive species. In response to excessive DNA damage, PARP [poly(ADP-ribose) polymerase] becomes overactivated, which can lead to cellular ATP depletion and cell death. The aim of our study was to evaluate whether PARP is expressed in post-ischemic liver, and to examine the effect of the administration of PJ-34 PARP inhibitor on liver function, histopathology, terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) reaction, and the oxidative state of the liver after injury.

METHODS

Male Wistar rats (weighing 250 g) underwent 60 min of normothermic, segmental liver ischemia followed by 30 min of reperfusion. The animals (n = 45) were divided into three groups: sham operated; I-R (control) treated with saline; and PJ-34 pre-treated (10 mg/kg i.v.). Hepatic microcirculation was monitored by a laser Doppler flowmeter. The reperfusion was characterized as the integral of the reperfusion area (RA) and the maximal plateau (PM). Histological alterations, TUNEL-reaction, serum, and liver tissue antioxidant levels, as well as serum ALT and AST levels were measured.

RESULTS

Upon reperfusion, the PJ-34 group had significantly (P < 0.05) higher flow rates than control groups (PM(PJ-34): 58%, PM(control): 37%; RA(PJ-34.): 48%, RA(control): 25%). At the end of the 30 min reperfusion, PJ-34 resulted in significantly (P < 0.05) lower serum ALT and AST levels and chemiluminescent intensity (free radicals) of the liver. The liver's free SH-group concentration and H-donor ability of the plasma was elevated in the PARP-inhibitor treated group. Positive staining for TUNEL, after PJ-34 pre-treatment was significantly increased (P < 0.05); in contrast, the control tissues were less positively stained for TUNEL but necrotic tissue was abundant.

CONCLUSION

PARP plays a pathogenetic role in the deterioration of the hepatic microcirculation and promotes hepatocellular necrosis in liver reperfusion injury.

Correlation between the expression of hypoxia-inducible factor-1α or histone deacetylase 1/metastasis-associated protein 1 complex and poor prognosis on human pancreatic carcinoma

21012

Background: Hypoxia-inducible factor-1a (HIF-1a) is a transcription factor that plays an important role in tumor growth and metastasis by regulating energy metabolism and inducing angiogenesis. Inhibition of histone deacetylase shows a marked inhibition of HIF-1a expression, however, the association between HIF-1a and histone deacetylase 1 (HDAC1) / metastasis-associated protein 1 (MTA1) is not fully understood. Here, we explored the involvement of HIF-1a and HDAC1/MTA1 in human pancreatic carcinoma. Methods: HIF-1a, HDAC1 and MTA1 expressions were detected by immunohistochemistry in surgical specimens obtained from 39 patients with pancreatic carcinoma. The correlations between the expression of HIF-1a, HDAC1 or MTA1 and clinical features, and the prognosis of patients with pancreatic carcinoma were then analyzed. Results: HIF-1a, HDAC1 and MTA1 positive stainings were found in 16 of 39 cases (41%), 22 of 39 cases (56%) and 12 of 39 cases (31%), respectively. There was no correlation between HIF-1a, HDAC1 or MTA1 expression levels and any of the clinical parameters examined. The five-year survival rate for pancreatic carcinoma patients with HIF-1a and HDAC1 positive stainings were significantly lower than for those patients with HIF-1a and HDAC1 negative stainings (P = 0.0243 and 0.0433). The MTA1 positive stainings group did not have a significantly worse prognosis than the MTA1 negative stainings group (P = 0.9694). In addition, the five-year survival rate for the HDAC1/MTA1 positive stainings group was statistically significantly worse than for the other groups (P = 0.0386). Conclusions: These results suggest that HIF-1a expression may be regulated through HDAC1/MTA1, which is associated with a poor prognosis on human pancreatic carcinoma, and indicate that HIF-1a and HDAC1/MTA1 is a promising therapeutic target in pancreatic carcinoma treatment.

No significant financial relationships to disclose.

Agrin, a novel basement membrane component in human and rat liver, accumulates in cirrhosis and hepatocellular carcinoma

Agrin is a multifunctional heparan sulfate proteoglycan originally discovered in the neuromuscular junctions and later observed in numerous other localizations. The presence of agrin in the liver, either healthy or diseased, has formerly not been reported. We detected agrin in minor amounts in the basement membranes of blood vessels and bile ducts in the healthy liver. The proliferation of bile ductules and the formation of new septal blood vessels in liver cirrhosis, as well as neoangiogenesis in the hepatocellular carcinoma (HCC) result in a dramatic increase in the quantity of agrin. Vascular and peribiliary basement membranes were strongly immunopositive for agrin in 29/29 human liver specimens with cirrhosis and HCC. However, sinusoidal walls of regenerative nodules in the cirrhotic liver consistently remained negative. Given the selectivity of agrin for tumor microvessels, agrin immunohistochemistry may prove helpful in recognizing malignant transformation in cirrhotic livers. Similar immunohistochemical observations were made on the liver of rats exposed to a combined cirrhosis/HCC induction treatment. In both human and rats, agrin probably originates from activated myofibroblasts, vascular smooth muscle cells and biliary epithelial cells. Increased agrin expression in human specimens, in the liver of 4/4 treated rats, as well as in isolated rat liver mesenchymal cells was verified by quantitative RT-PCR. Considering that agrin binds various growth factors, and it directly interacts with cell membrane receptors such as alphav-integrins, we hypothesize a stimulatory role for agrin in neoangiogenic processes such as tumor vascularization, and a supportive role in bile ductule proliferation.

Claudin-4 differentiates biliary tract cancers from hepatocellular carcinomas

The recently identified claudins are dominant components of tight junctions, responsible for cell adhesion, polarity and paracellular permeability. Certain claudins have been shown to have relevance in tumor development, with some of them, especially claudin-4, even suggested as future therapeutic target. The aim of the present study was to analyze the expression of claudin-4 in the biliary tree, biliary tract cancers and hepatocellular carcinomas. A total of 107 cases were studied: 53 biliary tract cancers, 50 hepatocellular carcinomas, 10 normal liver and 10 normal extrahepatic biliary duct samples. Immunohistochemical analysis was performed on conventional specimens and on tissue microarrays as well. Claudin-4 was further investigated by Western blot analysis and real-time RT-PCR. Intense membranous immunolabeling was found for claudin-4 in all biliary tract cancers unrelated to the primary site of origin, namely intrahepatic, extrahepatic or gallbladder cancers. Normal biliary epithelium showed weak positivity for claudin-4. In contrast, normal hepatocytes and tumor cells of hepatocellular carcinomas did not express claudin-4. The results of Western immunoblot analysis and real-time RT-PCR were in correlation with the immunohistochemical findings. Cytokeratins, as CK7 (92%) and CK19 (83%) were mostly positive in biliary tract cancers, however, one-third of hepatocellular carcinomas also expressed CK7 (34%). HSA antibody (HepPar1) reacted with the majority of hepatocellular carcinomas (86%), while being positive in a low percentage of the biliary tract cancers (8%). In conclusion, this is the first report of a significantly increased claudin-4 expression in biliary tract cancers, which represents a novel feature of tumors of biliary tract origin. Claudin-4 expression seems to be a useful marker in differentiating biliary tract cancers from hepatocellular carcinomas and could well become a potential diagnostic tool.

Comparative genetics and evolution of annexin A13 as the founder gene of vertebrate annexins

Annexin A13 (ANXA13) is believed to be the original founder gene of the 12-member vertebrate annexin A family, and it has acquired an intestine-specific expression associated with a highly differentiated intracellular transport function. Molecular characterization of this subfamily in a range of vertebrate species was undertaken to assess coding region conservation, gene organization, chromosomal linkage, and phylogenetic relationships relevant to its progenitor role in the structure-function evolution of the annexin gene superfamily. Protein diagnostic features peculiar to this subfamily include an alternate isoform containing a KGD motif, an elevated basic amino acid content with polyhistidine expansion in the 5'-translated region, and the conservation of 15% core tetrad residues specific to annexin A13 members. The 12 coding exons comprising the 58-kb human ANXA13 gene were deduced from BAC clone sequencing, whereas internal repetitive elements and neighboring genes in chromosome 8q24.12 were identified by contig analysis of the draft sequence from the human genome project. A unique exon splicing pattern in the annexin A13 gene was corroborated by coanalysis of mouse, rat, zebrafish, and pufferfish genomic DNA and determined to be the most distinct of all vertebrate annexins. The putative promoter region was identified by phylogenetic footprinting of potential binding sites for intestine-specific transcription factors. Mouse annexin A13 cDNA was used to map the gene to an orthologous linkage group in mouse chromosome 15 (between Sdc2 and Myc by backcross analysis), and the zebrafish cDNA permitted its localization to linkage group 24. Comparative analysis of annexin A13 from nine species traced this gene's speciation history and assessed coding region variation, whereas phylogenetic analysis showed it to be the deepest-branching vertebrate annexin, and computational analysis estimated the gene age and divergence rate. The unique, conserved aspects of annexin A13 primary structure, gene organization, and genetic maps identify it as the probable common ancestor of all vertebrate annexins, beginning with the sequential duplication to annexins A7 and A11 approximately 700 MYA, before the emergence of chordates.