Protective effect of the combination of essential oil from patchouli and tangerine peel against gastric ulcer in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Essential oil (EO) is the main extract of patchouli and tangerine peel with antiinflammatory, antiulcer, and other functions. However, the efficacy and mechanism of the combination of EO from patchouli and tangerine peel against gastric ulcer (GU) are unclear.

AIM OF THE STUDY

This study aims to reveal the protective effect of the combination of EO from patchouli and tangerine peel against GU in rats, as well as explore the optimal ratio and possible mechanism of EO in GU treatment.

MATERIALS AND METHODS

The GU model is executed via water immersion and restraint stress. The repair effect of EO in different proportions on gastric mucosa injury and the effects on serum gastrin (GAS), pepsinogen C (PGC), prostaglandin E2 (PGE2), and 5-hydroxytryptamine in GU rats were observed. The optimal ratio obtained was used in the second part to set different dose groups for further experiment. The effects of the different EO doses on gastric mucosal ulcer formation and gastric acid secretion were evaluated. The morphology of chief and parietal cells were observed via transmission electron microscopy. The contents of GAS, PGC, substance P (SP), cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), cholecystokinin (CCK), PGE2, and motilin (MTL) in serum in different groups were detected via enzyme-linked immunosorbent assay. Expressions of epidermal growth factor (EGF) and trefoil factor 2 (TFF2) protein in gastric tissues were detected via immunohistochemistry, and expressions of c-Jun N-terminal kinase (JNK), P53, Bcl-2-associated X protein (Bax), and Caspase-3 protein in gastric tissues were detected via western blotting.

RESULTS

The EO from patchouli and tangerine peel at 1:2 ratio of compatibility significantly improved gastric mucosal injury, decreased serum GAS and PGC contents, and increased the PGE2 level in serum (p < 0.05). The mixture of EO from patchouli and tangerine peel (Mix-EO) can reduce the formation of gastric mucosal ulcers, reduce gastric mucosal injury, improve the expansion of the endoplasmic reticulum of the chief cells, repair mitochondrial damage, and inhibit the secretion of gastric acid by parietal cells. Mix-EO at 300 mg/kg can reduce the expression of serum GAS, PGC, SP, CCK, and cAMP/cGMP (p < 0.05 or 0.01); increase the expression of EGF and TFF2 protein in gastric tissues (p < 0.01); and inhibit the expression of JNK, p53, Bax, and Caspase-3 proteins (p < 0.01).

CONCLUSION

The combination of EO from patchouli and tangerine peel can repair the gastric mucosal damage in GU rats and prevent the occurrence of ulcers by inhibiting the secretion of gastric acid, enhancing the defensive ability of gastric mucosa, and suppressing the apoptosis of gastric epithelial cells. Moreover, the optimal compatible ratio of patchouli and tangerine peel is 1:2.

Induction of Gastric Cancer by Successive Oncogenic Activation in the Corpus

BACKGROUND & AIMS

Metaplasia and dysplasia in the corpus are reportedly derived from de-differentiation of chief cells. However, the cellular origin of metaplasia and cancer remained uncertain. Therefore, we investigated whether pepsinogen C (PGC) transcript-expressing cells represent the cellular origin of metaplasia and cancer using a novel Pgc-specific CreERT2 recombinase mouse model.

METHODS

We generated a Pgc-mCherry-IRES-CreERT2 (Pgc-CreERT2) knock-in mouse model. Pgc-CreERT2/+ and Rosa-EYFP mice were crossed to generate Pgc-CreERT2/Rosa-EYFP (Pgc-CreERT2/YFP) mice. Gastric tissues were collected, followed by lineage-tracing experiments and histologic and immunofluorescence staining. We further established Pgc-CreERT2;KrasG12D/+ mice and investigated whether PGC transcript-expressing cells are responsible for the precancerous state in gastric glands. To investigate cancer development from PGC transcript-expressing cells with activated Kras, inactivated Apc, and Trp53 signaling pathways, we crossed Pgc-CreERT2/+ mice with conditional KrasG12D, Apcflox, Trp53flox mice.

RESULTS

Expectedly, mCherry mainly labeled chief cells in the Pgc-CreERT2 mice. However, mCherry was also detected throughout the neck cell and isthmal stem/progenitor regions, albeit at lower levels. In the Pgc-CreERT2;KrasG12D/+ mice, PGC transcript-expressing cells with KrasG12D/+ mutation presented pseudopyloric metaplasia. The early induction of proliferation at the isthmus may reflect the ability of isthmal progenitors to react rapidly to Pgc-driven KrasG12D/+ oncogenic mutation. Furthermore, Pgc-CreERT2;KrasG12D/+;Apcflox/flox mice presented intramucosal dysplasia/carcinoma and Pgc-CreERT2;KrasG12D/+;Apcflox/flox;Trp53flox/flox mice presented invasive and metastatic gastric carcinoma.

CONCLUSIONS

The Pgc-CreERT2 knock-in mouse is an invaluable tool to study the effects of successive oncogenic activation in the mouse corpus. Time-course observations can be made regarding the responses of isthmal and chief cells to oncogenic insults. We can observe stomach-specific tumorigenesis from the beginning to metastatic development.

Pepsinogen C expression-related lncRNA/circRNA/mRNA profile and its co-mediated ceRNA network in gastric cancer

The expression of pepsinogen C (PGC) is considered an ideal negative biomarker of gastric cancer, but its pathological mechanisms remain unclear. This study aims to analyze competing endogenous RNA (ceRNA) networks related to PGC expression at a post-transcriptional level and build an experimental basis for studying the role of PGC in the progression of gastric cancer. RNA sequencing technology was used to detect the differential expression (DE) profiles of PGC-related long non-coding (lnc)RNAs, circular (circ)RNAs, and mRNAs. Ggcorrplot R package and online database were used to construct DElncRNAs/DEcircRNAs co-mediated PGC expression-related ceRNA networks. In vivo and in vitro validations were performed using quantitative reverse transcription-PCR (qRT-PCR). RNA sequencing found 637 DEmRNAs, 698 DElncRNAs, and 38 DEcircRNAs. The PPI network of PGC expression-related mRNAs consisted of 503 nodes and 1179 edges. CFH, PPARG, and MUC6 directly interacted with PGC. Enrichment analysis suggested that DEmRNAs were mainly enriched in cancer-related pathways. Eleven DElncRNAs, 13 circRNAs, and 35 miRNA-mRNA pairs were used to construct ceRNA networks co-mediated by DElncRNAs and DEcircRNAs that were PGC expression-related. The network directly related to PGC was as follows: SNHG16/hsa_circ_0008197-hsa-mir-98-5p/hsa-let-7f-5p/hsa-let-7c-5p-PGC. qRT-PCR validation results showed that PGC, PPARG, SNHG16, and hsa_circ_0008197 were differentially expressed in gastric cancer cells and tissues: PGC positively correlated with PPARG (r = 0.276, P = 0.009), SNHG16 (r = 0.35, P = 0.002), and hsa_circ_0008197 (r = 0.346, P = 0.005). PGC-related DElncRNAs and DEcircRNAs co-mediated complicated ceRNA networks to regulate PGC expression, thus affecting the occurrence and development of gastric cancer at a post-transcriptional level. Of these, the network directly associated with PGC expression was a SNHG16/hsa_circ_0008197-mir-98-5p/hsa-let-7f-5p/hsa-let-7c-5p - PGC axis. This study may form a foundation for the subsequent exploration of the possible regulatory mechanisms of PGC in gastric cancer.

SNP interactions of PGC with its neighbor lncRNAs enhance the susceptibility to gastric cancer/atrophic gastritis and influence the expression of involved molecules

Multidimensional interactions of multiple factors are more important in promoting cancer initiation. Gene-gene interactions between protein-coding genes have been paid great attention, while rare studies refer to the interactions between encoding and noncoding genes. Our research group previously found encoding gene PGC polymorphisms could affect the susceptibility to atrophic gastritis (AG) and gastric cancer (GC). Interestingly, several SNPs in long noncoding RNA (lncRNA) genes, just adjacent to PGC, were found to be associated with AG risk and GC prognosis afterward. This study aims to explore the SNP interactions between PGC and its neighbor lncRNAs on the risk of AG and GC. Genotyping for seven PGC SNPs and seven lncRNA SNPs was conducted using Sequenom MassARRAY platform in a total of 2228 northern Chinese subjects, including 536 GC cases, 810 AG cases, and 882 controls. We found 15 pairwise PGC-lncRNAs SNPs had interactions: Five pairs were associated with AG risk, and ten pairs were associated with GC risk. Moreover, two GC-related interactions PGC rs6939861 with lnc-C6orf-132-1 rs7749023 and rs7747696 survived the Bonferroni correction (P_correction  = 0.049 and 0.007, respectively). Several combinations showed obvious epistasis and cumulative effects on disease risk. Some three-way interactions of SNPs with smoking and drinking could also be observed. Besides, a few interacting SNPs showed correlations with the expression levels of PGC protein and related lncRNAs in serum. Our study would provide research clues for further screening combination biomarkers uniting both protein-coding and noncoding genes with the potential in prediction of the susceptibility to GC and its precursor.

PGC TagSNP and its interaction with H. pylori and relation with gene expression in susceptibility to gastric carcinogenesis

Background

Pepsinogen C (PGC) plays an important role in sustaining the cellular differentiation during the process of gastric carcinogenesis. This study aimed to assess the role of PGC tagSNPs and their interactions with Helicobacter pylori (H. pylori) in the development of gastric cancer and its precursor, atrophic gastritis.

Methods

Four PGC tagSNPs (rs6941539, rs6912200, rs3789210 and rs6939861) were genotyped by Sequenom MassARRAY platform in a total of 2311 subjects consisting of 642 gastric cancer, 774 atrophic gastritis, and 895 healthy control subjects. The mRNA and protein expression levels of PGC in gastric tissues and in serum were respectively measured by quantitative reverse transcriptase–polymerase chain reaction (qRT-PCR), immunohistochemistry, and Eenzyme-linked immunoabsorbent assay (ELISA).

Results

We found associations between PGC rs3789210 CG/GG genotypes and reduced gastric cancer risk and between PGC rs6939861 A variant allele and increased risks of both gastric cancer and atrophic gastritis. As for the haplotypes of PGC rs6941539-rs6912200-rs3789210-rs6939861 loci, the TTCA and TTGG haplotypes were respectively associated with increased and reduced risks of both gastric cancer and atrophic gastritis; additionally, the CTCA haplotype was associated with increased atrophic gastritis risk. Very interestingly, rs6912200 CT/TT genotypes had a positive interaction with H. pylori, synergistically elevating the gastric cancer risk. Moreover, healthy subjects who carried rs6912200 CT, TT and CT/TT variant genotypes had lower histological and serum expression levels of PGC protein.

Conclusions

Our findings highlight an important role of PGC rs3789210 and rs6939861 in altering susceptibility to atrophic gastritis and/or gastric cancer. Moreover, people who carry rs6912200 variant genotypes exhibit higher gastric cancer risk in case of getting H. pylori infection, which strongly suggest a necessity of preventing and/or eliminating H. pylori infection in those individuals.

The interaction effects of pri-let-7a-1 rs10739971 with PGC and ERCC6 gene polymorphisms in gastric cancer and atrophic gastritis

Background

The aim of this study was to investigate the interaction effects of pri-let-7a-1 rs10739971 with pepsinogen C (PGC) and excision repair cross complementing group 6 (ERCC6) gene polymorphisms and its association with the risks of gastric cancer and atrophic gastritis. We hoped to identify miRNA polymorphism or a combination of several polymorphisms that could serve as biomarkers for predicting the risk of gastric cancer and its precancerous diseases.

Methods

Sequenom MassARRAY platform method was used to detect polymorphisms of pri-let-7a-1 rs10739971 G→A, PGC rs4711690 C→G, PGC rs6458238 G→A, PGC rs9471643 G→C, and ERCC6 rs1917799 in 471 gastric cancer patients, 645 atrophic gastritis patients and 717 controls.

Results

An interaction effect of pri-let-7a-1 rs10739971 polymorphism with ERCC6 rs1917799 polymorphism was observed for the risk of gastric cancer (P_interaction = 0.026); and interaction effects of pri-let-7a-1 rs10739971 polymorphism with PGC rs6458238 polymorphism (P_interaction = 0.012) and PGC rs9471643 polymorphism (P_interaction = 0.039) were observed for the risk of atrophic gastritis.

Conclusion

The combination of pri-let-7a-1 rs10739971 polymorphism and ERCC6 and PGC polymorphisms could provide a greater prediction potential than a single polymorphism on its own. Large-scale studies and molecular mechanism research are needed to confirm our findings.

[Correlation of pepsinogen C (PGC) gene insertion/deletion polymorphism to PGC protein expression in gastric mucosa and serum]

BACKGROUND AND OBJECTIVE

Human pepsinogen C (PGC) is an aspartic protease synthesized in gastric mucosa. PGC gene insertion/deletion polymorphism, which is located between exon 7 and 8, has been found to associate with gastric cancer (GC) susceptibility. This study was to investigate the relationship between PGC polymorphism with protein expression of PGC in gastric mucosa and serum.

METHODS

PGC insertion/deletion polymorphism was evaluated by PCR, followed by direct DNA sequencing in 493 cases of GC, atrophic gastritis (AG), gastric erosion ulcer (GEU) and superficial gastritis (SG). PGC protein expression in gastric mucosa was measured by immunohistochemistry. The serum PGC level was determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

In accordance with the following order SG-->GEU-->GA-->GC, the frequency of PGC homozygous allele 1 was gradually increased, which was higher in GC than in SG (P=0.018); while the protein expression of PGC in gastric mucosa was gradually decreased (P<0.01), along with a gradual decrease in the strong positive rate of PGC (P<0.05) except for SG vs. GEU. The serum level of PGC was significantly lower in SG than in GU(P=0.000) and GC(P=0.000). The frequency of PGC homozygous allele 1 was negatively correlated to PGC protein expression in gastric mucosa (r=-0.1085, P=0.023). From homozygous allele 1 to heterozygous allele 1, and to other genotypes, the PGC positive rate was gradually increased in gastric mucosa, with significant differences between homozygous allele 1 and other genotypes (P=0.009); while the strong-positive rate of PGC was gradually decreased only in SG group (P=0.047).

CONCLUSION

PGC gene insertion/deletion polymorphism is negatively related to PGC protein expression in gastric mucosa, but is not related to the serum PGC level.

[Interaction between an insertion/deletion polymorphism in pepsinogen C and Helicobacter pylori infection in the development of gastric cancer]

OBJECTIVE

This study was designed to investigate the interaction between pepsinogen C(PGC) insertion/deletion polymorphism and Helicobacter pylori(Hp) infection, together with its different subtype strains, in the development of gastric cancer (GC).

METHODS

PGC Genotypes were determined by polymerase chain reaction (PCR) assay in 564 subjects with superficial gastritis (NOR), gastric ulcer (GU), atrophic gastritis (AG) and GC, who were frequency-matched as 1:1. Serum Hp-IgG antibodies were determined by an enzyme linked immunoadsorbent assay (ELISA). Hp genetic subtypes in 171 patients with Hp infection were determined by PCR methods.

RESULTS

In GU, AG and GC, the OR of interaction was 8.69 (P = 0.049), 11.16 (P = 0.02), and 10.61 (P = 0.03), respectively; the interaction index of PGC homozygous allele 1 genotype and Hp infection was 5.40, 6.48 or 4.34, respectively; the attributable proportions were 0.721, 0.770 and 0.697, respectively. In AG and GC, no significant interactions were observed between PGC polymorphism and Hp genetic subtypes.

CONCLUSION

The findings of this study suggest that PGC insertion/deletion polymorphism and Hp infection seem to present a positive interaction in the development of gastric cancer. While no interactions may be present between PGC polymorphism and Hp genetic subtypes.

Regulation of progastricsin mRNA levels in sea bass (Dicentrarchus labrax) in response to fluctuations in food availability

In this study the sea bass (Dicentrarchus labrax) pepsinogen C gene was isolated. The nucleotide sequences of all exons are presented. The organization of the gene is compatible with that of other aspartic proteinases. The predicted 388-residue amino acid (aa) sequence of sea bass pepsinogen C consists of a signal sequence of 16 amino acid residues, an activation peptide of 43 residues, and the mature pepsin of 329 residues containing the two characteristic active-site aspartic acids. We also analyzed fasting-induced changes in the expression of progastricsin mRNA, using real-time RT-PCR absolute quantification. Progastricsin mRNA copy number was downregulated under conditions of negative energy balance, such as starvation, and upregulated during positive energy balance, such as refeeding. These findings offer new information about the sea bass progastricsin gene and support a role of this gastric digestive enzyme in the regulation of food intake in sea bass.

mGluR1 in the fundic glands of rat stomach

l-glutamate not only confers cognitive discrimination for umami taste in the oral cavity, but also conveys sensory information to vagal afferent fibers in the gastric mucosa. We used RT-PCR, western blotting, and immunohistochemistry to demonstrate that mGluR1 is located in glandular stomach. Double staining revealed that mGluR1 is found at the apical membrane of chief cells and possibly in parietal cells. Moreover, a diet with 1% l-glutamate induced changes in the expression of pepsinogen C mRNA in stomach mucosa. These data suggest that mGluR1 is involved in the gastric phase regulation of protein digestion.

Transcription factor SOX2 up-regulates stomach-specific pepsinogen A gene expression

PURPOSE

Transcription factor SOX2 is expressed in normal gastric mucosae but not in the normal colon. We aimed to clarify the role of SOX2 with reference to pepsinogen expression in the gastrointestinal epithelium.

METHODS

We analyzed expression of SOX2 and pepsinogens, differentiation markers of the stomach, in ten gastric cancer (GC) and ten colorectal cancer (CRC) cell lines. The effects of over-expression and down-regulation of SOX2 on pepsinogen expression were also examined.

RESULTS

Six GC and five CRC cell lines showed SOX2 expression on RT-PCR. Expression of pepsinogen A was detectable in eight GC and seven CRC cell lines, whereas the majority of the cell lines expressed pepsinogen C. Over-expression of SOX2 up-regulated expression of pepsinogen A but not that of pepsinogen C in 293T human embryonic kidney cells, and some GC and CRC cell lines. Moreover, pepsinogen A expression was significantly reduced by SOX2 RNA interference in two GC cell lines.

CONCLUSION

These data suggest that SOX2 plays an important role in regulation of pepsinogen A, and ectopic expression of SOX2 may be associated with abnormal differentiation of colorectal cancer cells.

[Correlation between an insertion-deletion polymorphism in the pepsinogen C gene and gastric cancer as well as its precursors]

OBJECTIVE

To assess the relationship between the insert-deletion polymorphism in the Human pepsinogen (PGC) gene and susceptibility to gastric cancer, together with its precursors, and to investigate the interaction between PGC polymorphism and H. pylori infection in the development of gastric cancer.

METHODS

PGC gene polymorphism in 141 patients with gastric cancer and 564 matched non-cancer controls were detected by polymerase chain reaction (PCR), and the relation between the PGC polymorphism and gastric cancer was examined. Serum H. pylori-IgG was determined with ELISA method. The odds ratios and 95% confidence intervals (95% CI) were calculated using unconditional logistic regression model. The effect-modified model was used to evaluate the PGC-H. pylori interaction.

RESULTS

No significant association between the frequency of homogenous allele 1 of PGC gene and the sex and age of the subjects was observed. The subjects with the homogenous allele 1 had an increased risk of developing atrophic gastritis (OR: 3.103, 95% CI: 1.440-6.686), and gastric cancer (OR: 2.962, 95% CI: 1.370-6.404), and Intestinal metaplasia (OR: 1.659, 95% CI: 0.998-2.757) comparing with those with the non-homogenous allele 1. For subjects carrying both homogenous allele 1 and H. pylori-IgG positive, there was an significant increased risk of developing atrophic gastritis and gastric cancer (likelihood test ratio test: P = 0.023, P = 0.005).

CONCLUSION

PGC gene polymorphism may be associated with susceptibility to gastric cancer and atrophic gastritis. The PGC gene polymorphism and H. pylori infection seem to display an interaction in the development of gastric cancer.

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.

Gene Expression Profiles in Pancreatic Intraepithelial Neoplasia Reflect the Effects of Hedgehog Signaling on Pancreatic Ductal Epithelial Cells

Invasive pancreatic cancer is thought to develop through a series of noninvasive duct lesions known as pancreatic intraepithelial neoplasia (PanIN). We used cDNA microarrays interrogating 15,000 transcripts to identify 49 genes that were differentially expressed in microdissected early PanIN lesions (PanIN-1B/2) compared with microdissected normal duct epithelium. In this analysis, a cluster of extrapancreatic foregut markers, including pepsinogen C, MUC6, KLF4, and TFF1, was found to be up-regulated in PanIN. Up-regulation of these genes was further validated using combinations of real-time reverse transcription-PCR, in situ hybridization, and immunohistochemistry in a total of 150 early PanIN lesions from 81 patients. Identification of these gastrointestinal transcripts in human PanIN prompted assessment of other foregut markers by both semiquantitative and real-time reverse transcription-PCR, revealing similar up-regulation of Sox-2, Gastrin, HoxA5, GATA4/5/6, Villin and Forkhead 6 (Foxl1). In contrast to frequent expression of multiple gastric epithelial markers, the intestinal markers intestinal fatty acid binding protein, CDX1 and CDX2 were rarely expressed either in PanIN lesions or in invasive pancreatic cancer. Hedgehog pathway activation induced by transfection of immortalized human pancreatic ductal epithelial cells with Gli1 resulted in up-regulation of the majority of foregut markers seen in early PanIN lesions. These data show frequent up-regulation of foregut markers in early PanIN lesions and suggest that PanIN development may involve Hedgehog-mediated conversion to a gastric epithelial differentiation program.

Pepsinogen C expression in intestinal IEC-6 cells

Pepsinogen C (PGC) is the inactive precursor of pepsin C, which is a member of the aspartic proteinase family of proteolytic enzymes, and is found within the vertebrate stomach. The precursor molecule is synthesised within the gastric epithelial cells and secreted into the gastric lumen where it undergoes an autocatalytic activation under acidic conditions to the proteolytic molecule. However, the synthesis of PGC has also been reported in numerous non-gastric tissues including the prostate gland and the Brunner's gland of the small intestine. The physiological significance of PGC in these tissues is not known and studies are limited by the lack of appropriate in vitro cell models. We report here the use of the rat intestinal cell line, IEC-6, as an in vitro model to study the role of pepsinogen C in the intestine. PGC expression was detected in the IEC-6 cells by RT-PCR and immunocytochemistry, using a PGC specific antibody, localised the protein to cytoplasmic secretory granules. Enzymatic assay confirmed the presence of a functional protein exhibiting pepsin activity. Using semi-quantitative RT-PCR we showed that PGC gene expression was up-regulated by the gastro-intestinal hormones gastrin and secretin, and forskolin which stimulates adenylate cyclase activity. This study demonstrates that the IEC-6 cells provide a unique in vitro model for studying pepsinogen C and its potential role(s) in the small intestine.

Pepsinogen C: a type 2 cell-specific protease

Pepsinogen C, also known as progastricsin or pepsinogen II, is an aspartic protease expressed primarily in gastric chief cells. Prior microarray studies of an in vitro model of type 2 cell differentiation indicated that pepsinogen C RNA was highly induced, comparable to surfactant protein RNA induction. Using second-trimester human fetal lung, third-trimester postnatal and adult lung, and a model of type 2 cell differentiation, we examined the specificity of pepsinogen C expression in lung. Pepsinogen C RNA and protein were only detected in >22 wk gestation samples of neonatal lung or in adult lung tissue. By immunohistochemistry and in situ hybridization, pepsinogen C expression was restricted to type 2 cells. Pepsinogen C expression was rapidly induced during type 2 cell differentiation and rapidly quenched with dedifferentiation of type 2 cells after withdrawal of hormones. In all samples, pepsinogen C expression occurred concomitantly with or in advance of processing of surfactant protein-B to its mature 8-kDa form. Our results indicate that pepsinogen C is a type 2 cell-specific marker that exhibits tight developmental regulation in vivo during human lung development, as well as during in vitro differentiation and dedifferentiation of type 2 cells.

A two-step method for the extraction of high-quality RNA from endoscopic biopsies

The use of molecular techniques such as quantitative RT-PCR depends on the quality of cellular RNA. In particular, RNA extraction from endoscopic biopsies is difficult with respect to yield, and especially integrity. Endoscopic biopsies taken from the gastric antrum, corpus and duodenum were subjected to various RNA extraction protocols, and the RNA was used for quantitative RT-PCR. The subsequent use of two methods, (i) a phenol/chloroform extraction and (ii) a column-based extraction method, resulted in a yield of 4.5 microg total RNA per biopsy with reliable quality in 80% of samples. The quantitative RT-PCR analysis revealed that only RNA samples that clearly show both 18S- and 28S-RNA bands in agarose gel electrophoresis were suitable for quantitative RT-PCR as shown by expression of corpus-specific pepsinogen C-mRNA and the duodenum-specific multi-drug resistance protein-1 (mdr-1)-mRNA. In partially degraded RNA, pepsinogen C, mdr-1, or beta-actin mRNAs were still detectable, but the quantitative determination gave inconsistent data. The two-step method described here is a suitable option for extracting high-quality RNA from endoscopic biopsies when other standard protocols fail.

Association between pepsinogen C gene polymorphism and genetic predisposition to gastric cancer

AIM: To identify a molecular marker for gastric cancer, and to investigate the relationship between the polymorphism of pepsinogen C (PGC) gene and the genetic predisposition to gastric cancer.

METHODS: A total of 289 cases were involved in this study. 115 cases came from Shenyang area, a low risk area of gastric cancer, including 42 unrelated controls and 73 patients with gastric cancer. 174 cases came from Zhuanghe area, a high-risk area of gastric cancer, including 113 unrelated controls, and 61 cases from gastric cancer kindred families. The polymorphism of PGC gene was detected by polymerase chain reaction (PCR) and the relation between the genetic polymorphism of PGC and gastric cancer was examined.

RESULTS: Four alleles, 310 bp (allele 1), 400 bp (allele 2), 450 bp (allele 3), and 480 bp (allele 4) were detected by PCR. The frequency of allele 1 was higher in patients with gastric cancer than that in controls. Genotypes containing homogenous allele 1 were significantly more frequent in patients with gastric cancer than that in controls (0.33, 0.14, χ² = 3.86, P < 0.05). There was no significant difference between the control group of Zhuanghe and the group of gastric cancer kindred. But the frequency of allele 1 was higher in control group of Zhuanghe area than that in control group of Shenyang area and genotypes containing homogenous allele 1 were significantly more frequent in the control group of Zhuanghe area than those in control group of Shenyang area (0.33, 0.14, χ² = 4.32, P < 0.05). In the group of gastric cancer kindred the frequency of allele 1 was significantly higher than that in control group of Shenyang area (0.5164, 0.3571, χ² = 4.47, P < 0.05). Genotypes containing homogenous allele 1 were significantly more frequent in the group of gastric cancer kindred than those in control group of Shenyang area (0.36, 0.14, χ² = 4.91, P < 0.05).

CONCLUSION: These results suggest that there is some relation between pepsinogen C gene polymorphism and gastric cancer, and the person with homogenous allele 1 predisposes to gastric cancer than those with other genotypes. Pepsinogen C gene polymorphism may be used as a genetic marker for a genetic predisposition to gastric cancer. The distribution of pepsinogen C gene polymorphism in Zhuanghe, a high-risk area of gastric cancer, is different from that in Shenyang, a low risk area of gastric cancer.

Pepsinogens, progastricsins, and prochymosins: structure, function, evolution, and development

Five types of zymogens of pepsins, gastric digestive proteinases, are known: pepsinogens A, B, and F, progastricsin, and prochymosin. The amino acid and/or nucleotide sequences of more than 50 pepsinogens other than pepsinogen B have been determined to date. Phylogenetic analyses based on these sequences indicate that progastricsin diverged first followed by prochymosin, and that pepsinogens A and F are most closely related. Tertiary structures, clarified by X-ray crystallography, are commonly bilobal with a large active-site cleft between the lobes. Two aspartates in the center of the cleft, Asp32 and Asp215, function as catalytic residues, and thus pepsinogens are classified as aspartic proteinases. Conversion of pepsinogens to pepsins proceeds autocatalytically at acidic pH by two different pathways, a one-step pathway to release the intact activation segment directly, and a stepwise pathway through a pseudo-pepsin(s). The active-site cleft is large enough to accommodate at least seven residues of a substrate, thus forming S4 through S'3 subsites. Hydrophobic and aromatic amino acids are preferred at the P1 and P'1 positions. Interactions at additional subsites are important in some cases, for example with cleavage of kappa-casein by chymosin. Two potent naturally occurring inhibitors are known: pepstatin, a pentapeptide from Streptomyces, and a unique proteinous inhibitor from Ascaris. Pepsinogen genes comprise nine exons and may be multiple, especially for pepsinogen A. The latter and progastricsin predominate in adult animals, while pepsinogen F and prochymosin are the main forms in the fetus/infant. The switching of gene expression from fetal/infant to adult-type pepsinogens during postnatal development is noteworthy, being regulated by several factors, including steroid hormones.

Phylogenetic position of Eulipotyphla inferred from the cDNA sequences of pepsinogens A and C

Although to date the phylogenetic position of the provisional order Eulipotyphla has been assessed by various molecular markers, it has not been conclusively clarified due to low statistical supporting values and inconsistent results. To clarify the phylogenetic position of Eulipotyphla, we cloned cDNAs for pepsinogens A and C from five mammalian species belonging to four different orders and determined their nucleotide sequences. Molecular phylogenetic analysis based on the 1st and 2nd codon positions of the protein-coding region of cDNA sequences strongly supported the close relationship between Eulipotyphla and Chiroptera. Carnivora was found to be a sister group to these two orders. The monophyly of the order Rodentia and that of the cohort Glires (Rodentia and Lagomorpha) was also shown by the present phylogenetic trees of pepsinogens.

An ovarian progastricsin is present in the trout coelomic fluid after ovulation

An up-regulated cDNA fragment was isolated using a differential display polymerase chain reaction between ovulatory and postovulatory brook trout ovarian tissues. Using this fragment as a probe, a full-length cDNA of 1783 base pairs was obtained from an ovarian cDNA library. The cDNA presumably codes for a 383-amino acid protein with strong sequence similarity to an aspartic protease, progastricsin (EC 3.4.23.3), also known as pepsinogen C. On Northern blots of ovarian tissue, the trout progastricsin cDNA hybridized with a 1.8-kilobase transcript that was strongly up-regulated 4-6 days after ovulation. Of all other tissues tested, a transcript was only detected in the stomach. A recombinant trout progastricsin protein was produced and used to raise an antibody. On Western blots of ovarian tissue, the progastricsin antibody recognized a single 39-kDa protein that was present in the ovary only following ovulation. On Western blots of coelomic fluid, the 39-kDa protein was strongly detected 4-10 days after ovulation. The trout progastricsin was immunocytochemically localized to the granulosa cells of postovulatory follicles, suggesting that it is released from this tissue into the coelomic fluid following ovulation. Progastricsin has been found in the stomach, prostate, seminal vesicle, seminal fluid, and pancreas of vertebrates; however, this is the first report of a progastricsin in an animal ovary.

Amphibian pepsinogens: purification and characterization of xenopus pepsinogens, and molecular cloning of Xenopus and bullfrog pepsinogens

Two pepsinogens (Pg C and Pg A) were isolated from the stomach of adult Xenopus laevis by Q-Sepharose, Sephadex G-75, and Mono-Q column chromatographies. Autolytic conversion and activation of the purified Pgs into the pepsins were examined by acid treatment. We determined the amino acid sequences from the NH2-termini of Pg C, pepsin C, Pg A, and pepsin A. Based on the sequences, the cDNAs for Pg C and Pg A were cloned from adult stomach RNA, and the complete amino acid sequences of the Pg C and Pg A were predicted. In addition, a Pg A cDNA was cloned from the stomach of adult bullfrog Rana catesbeiana, and the primary structure of the Pg A was predicted. Molecular phylogenetic analysis showed that such anuran Pg C and Pg A belong to the Pg C group and the Pg A group in vertebrates, respectively. The molecular properties of Pg C and Pg A, such as size, sequences of the activation peptide and active site, profile of autolytic activation, and pH dependency of proteolytic activity of the activated forms, pepsin C and pepsin A, resemble those of Pgs found in other vertebrates. However, the hemoglobin-hydrolyzing activity of Xenopus pepsin C is completely inhibited in the presence of equimolar pepstatin, an inhibitor of aspartic proteinases. Thus, the Xenopus pepsin C differs significantly from other vertebrate pepsins C in its high susceptibility to pepstatin, and closely resembles A-type pepsins.

New world monkey pepsinogens A and C, and prochymosins. Purification, characterization of enzymatic properties, cDNA cloning, and molecular evolution

Pepsinogens A and C, and prochymosin were purified from four species of adult New World monkeys, namely, common marmoset (Callithrix jacchus), cotton-top tamarin (Saguinus oedipus), squirrel monkey (Saimiri sciureus), and capuchin monkey (Cebus apella). The occurrence of prochymosin was quite unique since this zymogen is known to be neonate-specific and, in primates, it has been thought that the prochymosin gene is not functional. No multiple form has been detected for any type of pepsinogen except that two pepsinogen-A isozymogens were identified in capuchin monkey. Pepsins A and C, and chymosin hydrolyzed hemoglobin optimally at pH 2-2.5 with maximal activities of about 20, 30, and 15 units/mg protein. Pepsins A were inhibited in the presence of an equimolar amount of pepstatin, and chymosins and pepsins C needed 5- and 100-fold molar excesses of pepstatin for complete inhibition, respectively. Hydrolysis of insulin B chain occurred first at the Leu15-Tyr16 bond in the case of pepsins A and chymosins, and at either the Leu15-Tyr16 or Tyr16-Leu17 bond in the case of pepsins C. The presence of different types of pepsins might be advantageous to New World monkeys for the efficient digestion of a variety of foods. Molecular cloning of cDNAs for three types of pepsinogens from common marmoset was achieved. A phylogenetic tree of pepsinogens based on the nucleotide sequence showed that common marmoset diverged from the ancestral primate about 40 million years ago.

Peptic ulcer inheritance in patients with elevated serum pepsinogen group A levels and without infection of Helicobacter pylori

BACKGROUND

Peptic ulcer has multifactorial aetiology, including genetic factors. We have identified a family with pepsinogen Group A levels higher than normal, with a high prevalence of ulcer disease and a low prevalence of Helicobacter pylori infection.

AIMS

Performing linkage analysis in the identified family

PATIENTS AND METHODS

We examined the segregation of pepsinogens with microsatellite dinucleotide repeat DNA markers along chromosome 11 (D11S480, PYGM) for pepsinogen Group A and along chromosome 6 [D6S105, D6S 1610, TRMI) for pepsinogen Group C.

RESULTS

In markers examined along chromosome 11, linkage analysis provided no evidence for significant causal mutation but, controlling for some risk factors we observed that the probability of falling ill, increases. The linkage analysis along chromosome 6 for pepsinogen Group C did not show a uniform genetic profile.

CONCLUSIONS

This study evaluates the hypothesis of peptic ulcer inheritance at least in a small group of patients without the common risk factors.