Pepsinogen C expression in intestinal IEC-6 cells

Pepsinogen C expression, regulation and its relationship with cancer

Pepsinogen C (PGC) belongs to the aspartic protease family and is secreted by gastric chief cells. PGC could be activated to pepsin C and digests polypeptides and amino acids, but as a zymogen PGC’s functions is unclear. In normal physiological conditions, PGC is initially detected in the late embryonic stage and is mainly expressed in gastric mucosa. The in situ expression of PGC in gastric mucosa is decreased considerably in the process of superficial gastritis → atrophic gastritis → gastric cancer (GC), proving that PGC is a comparatively ideal negative marker of GC. Serum PGC, and PGA levels and the PGA/PGC ratio have satisfactory sensitivity, specificity and price–quality ratio for predicting high GC risk. Ectopic PGC expression is significantly increased in prostate cancer, breast cancer, ovary cancer and endometrial cancer. In those sex-related cancers high level PGC expression indicates better prognosis and longer survival. The regulation of PGC expression involves genetic and epigenetic alteration of the encoding PGC gene, hormones modulation and interactions between PGC with other transcription factors and protein kinases. More and more research evidence hinted that PGC has strong correlation with cancer. In the systematic review, we respectively elaborate the structure, potential physiological functions, expression characteristics and regulation of PGC, and especially focus on the relationship between PGC expression and cancer to highlight the role of PGC in the tumorigenesis and its application value in clinical practice.

Progastriscin: structure, function, and its role in tumor progression

Progastricsin (PGC) is a major seminal plasma protein having aspartyl proteinases-like activity and showing close sequence similarity to pepsins. PGC is also present as zymogen in gastric mucosa. In this article, we have reviewed all important features of PGC. Furthermore, we have compared all features of PGC with those of different aspartyl proteinases. The complete amino acid sequence of PGC reveals that it is composed of 374 residues (gastricsin moiety of 331 residues and the activation segment of 43 residues). The gene of human PGC is located at single locus on chromosome 6, whereas the human pepsinogen genetic locus is polymorphic and codes for at least three distinct polypeptide sequences on chromosome 11. The major useful function of PGC includes production of pro-antimicrobial substance in seminal plasma. The crystal structure of human PGC is known, which shows that it is quite similar to that of porcine pepsinogen. The tertiary structure of PGC is comprised of commonly bilobal structure with a large active-site cleft between the lobes. Two aspartate residues in the center of the cleft, namely Asp32 and Asp215, function as catalytic residues. The sequence and structural features of PGC indicate that it is diverged from its pepsinogen ancestor in the early phase of the evolution of gastric aspartyl proteinases. Our detailed review of PGC structure, function and activation mechanism will also be of interest to cancer biologists as well as gastroenterologists.

Overall survival in women with breast cancer: the influence of pepsinogen C gene polymorphism

We aimed to study the role of an insertion/deletion polymorphism in the Pepsinogen C (PGC) gene in the clinical outcome of 172 breast cancer patients. The six polymorphic alleles were amplified using PCR. Our results indicate that patients carrying the allele 6 present a higher 5-year survival mean (83.4% of 6 allele carriers were alive at 5 years vs. only 68.6% of noncarriers, p=0.001), suggesting a role for this polymorphism in the outcome of breast cancer patients. We hypothesize that PGC polymorphism can be a predictive biomarker in breast cancer, contributing to an individual profile of great interest in clinical oncology.

The chicken host peptides, gallinacins 4, 7, and 9 have antimicrobial activity against Salmonella serovars

The gallinacin genes clustered on chromosome 3 of the chicken (Gallus gallus domesticus) genome encode a group of cationic antimicrobial peptides characteristic of the beta-defensins. In this study, gallinacins 4, 7, and 9, all predicted to contain the conserved pattern of cysteines typical of beta-defensins but differing in their charge and hydrophobicity, were characterised for their in vivo gene expression patterns and in vitro antimicrobial activities against Salmonella serovars. Reverse-transcription PCR analyses of chicken epithelial tissues indicated gallinacin (Gal) 7 expression to be ubiquitous while Gal 4 and Gal 9 expression appeared localized to specific epithelial tissues including the ovary, trachea, and lung, respectively. In addition Gal 7, but neither Gal 4 nor Gal 9, expression was identified in tissues taken from the non-domesticated bird species, Parus caeruleus, Larus argentatus, and Columba palambus. Analysis of Gal 7 expression in chickens in response to an oral challenge with either Salmonella enterica serovar Typhimurium SL1344 or Salmonella enteriditis indicated no significant increase in small intestinal Gal 7 mRNA expression although a significant increase (p <0.05) was detected in the liver, suggesting that, in response to Salmonella infection Gal 7 expression is inducible in the liver. Neither Gal 4 nor Gal 9 expression was induced in the chicken small intestine in response to the oral Salmonella infection. The antimicrobial capabilities of Gals 4, 7, and 9 against Salmonella serovars including S. typhimurium SL1344 and S. enteriditis were investigated in vitro using recombinant His-tagged peptides and a time-kill assay. The antimicrobial activity data indicated the potency of the recombinant gallinacins against the Salmonella serovars to be in the order Gal 9> or=4>7, and provided evidence for the synergistic interaction of Gals 7 and 9 against S. enteriditis. These results support in silico data that Gals 4, 7, and 9 are part of the innate defences of the chicken and function in microbial killing activities.

Gastric cancer in a Caucasian population: Role of pepsinogen C genetic variants

AIM: To study the role of an insertion/deletion polymorphism in the pepsinogen C (PGC) gene, an effective marker for terminal differentiation of the stomach mucosa, in the susceptibility to the development of gastric lesions.

METHODS: The study was performed with 99 samples of known gastric lesions and 127 samples without evidence of neoplastic disease. PCR was employed and the 6 polymorphic alleles were amplified: Allele 1 (510 bp), Allele 2 (480 bp), Allele 3/4 (450/460 bp), Allele 5 (400 bp) and Allele 6 (310 bp).

RESULTS: Our results revealed that Allele 6 carriers seemed to have protection against the development of any gastric lesion (OR = 0.34; P < 0.001), non-dysplastic lesions associated with gastric adenocarcinoma such as atrophy or intestinal metaplasia (OR = 0.28; P < 0.001) or invasive GC (OR = 0.39; P = 0.004).

CONCLUSION: Our study reveals that the Allele 6 carrier status has a protective role in the development of gastric lesions, probably due to its association with higher expression of PGC. Moreover, the frequency of Allele 6 carriers in the control group is far higher than that obtained in Asian populations, which might represent a genetic gap between Caucasian and Asian populations.

Preparation and testing of stationary phases and modified capillaries for affinity chromatography and affinity capillary electrophoresis of pepsin

Three stationary phases have been prepared for affinity liquid chromatography isolation and separation of porcine and human pepsin. The phases contain 3,5-diiodo-L-tyrosine (DIT) bound to the supports HEMA BIO VS, HEMA BIO E and EPOXY TOYOPEARL. These phases have been tested on a model sample of porcine pepsin A and applied to human pepsin. Fractions have been collected and the chymase activity determined in selected analyses. For affinity CE, capillaries have been prepared by modifying the wall with 3-aminopropyltriethoxysilane, followed either by direct binding of DIT, or by binding L-tyrosine that was subsequently iodated. The dissociation constant K(d) has been determined for the pepsin-DIT complex from the changes in the electrophoretic mobilities.

Induction of cationic chicken liver-expressed antimicrobial peptide 2 in response to Salmonella enterica infection

Cationic antimicrobial peptides constitute part of the innate immune system and provide an essential role in the defense against infection. At present there is a paucity of information regarding the antimicrobial profile of the chicken (Gallus gallus). Using in silico studies, an expressed sequence tag (EST) clone was identified which encodes a novel cationic antimicrobial peptide, chicken liver-expressed antimicrobial peptide 2 (cLEAP-2). The predicted amino acid sequence composed a prepropeptide, and the active peptide contained four conserved cysteine amino acids. The gene was localized to chromosome 13, and analysis of the genome revealed three exons separated by two introns. The cLEAP-2 gene was expressed in a number of chicken epithelial tissues including the small intestine, liver, lung, and kidney. Northern analysis identified liver-specific cLEAP-2 splice variants, suggesting some degree of tissue-specific regulation. To investigate whether cLEAP-2 expression was constitutive or induced in response to microbial infection, 4-day-old birds were orally infected with Salmonella. Analyses of cLEAP-2 expression by semiquantitative reverse transcription-PCR indicated that cLEAP-2 mRNA was upregulated significantly in the small intestinal tissues and the liver, indicative of direct and systemic responses. The antimicrobial activity of cLEAP-2 against Salmonella was analyzed in vitro with a time-kill assay and recombinant cLEAP-2. Interestingly Salmonella enterica serovar Typhimurium SL1344 showed increased susceptibility to the active cationic peptide (amino acids 37 to 76) compared to S. enterica serovar Typhimurium C5 and Salmonella enteritidis. Taken together, these data suggest that cationic cLEAP-2 is part of the innate host defense mechanisms of the chicken.