CD36 polymorphisms and the age of disease onset in patients with pathogenic variants within the mutation cluster region of APC

Background

Familial adenomatous polyposis (FAP) is an autosomal dominant condition that predisposes patients to colorectal cancer. FAP is the result of a loss of APC function due to germline pathogenic variants disrupting gene expression. Genotype-phenotype correlations are described for FAP. For example attenuated forms of the disease are associated with pathogenic variants at the 5’ and 3’ ends of APC whilst severe forms of the disease appear to be linked to variants occurring in the mutation cluster region (MCR) of the gene. Variants occurring in the MCR are phenotypically associated with hundreds to thousands of adenomas carpeting the colon and rectum and patients harbouring changes in this region have a high propensity to develop colorectal cancer. Not all patients who carry pathogenic variants in this region have severe disease which may be a result of environmental factors. Alternatively, phenotypic variation observed in these patients could be due to modifier genes that either promote or inhibit disease expression. Mouse models of FAP have provided several plausible candidate modifier genes, but very few of these have survived scrutiny. One such genetic modifier that appears to be associated with disease expression is CD36. We previously reported a weak association between a polymorphism in CD36 and a later age of disease onset on a relatively small FAP patient cohort.

Methods

In the current study, we enlarged the FAP cohort. 395 patients all carrying pathogenic variants in APC were tested against three CD36 Single Nucleotide Polymorphisms (SNP)s (rs1049673, rs1761667 rs1984112), to determine if any of them were associated with differences in the age of disease expression.

Results

Overall, there appeared to be a statistically significant difference in the age of disease onset between carriers of the variant rs1984112 and wildtype. Furthermore, test equality of survivor functions for each SNP and mutation group suggested an interaction in the Log Rank, Wilcoxon, and Tarone-Ware methods for rs1049673, rs1761667, and rs1984112, thereby supporting the notion that CD36 modifies disease expression.

Conclusions

This study supports and strengthens our previous findings concerning CD36 and an association with disease onset in FAP, AFAP and FAP-MCR affected individuals. Knowledge about the role CD36 in adenoma development may provide greater insight into the development of colorectal cancer.

Phenylketonuria is not a risk factor for gut mucosa inflammation: a preliminary observation

BACKGROUND

Phenylketonuria (PKU) is an inborn error of amino acid metabolism in which high phenylalanine (Phe) concentrations in the central nervous system adversely affect its development and functioning. In PKU high oxidative stress and inefficiency of free radical scavenging may lead to systemic chronic inflammation. We hypothesised that in PKU gut mucosa is chronically inflamed and that this leads to release of calprotectin from neutrophils and monocytes.

AIM

The aim of this study was to compare intestinal mucosa inflammation status, as measured using fecal calprotectin, in patients with PKU irrespective of compliance, and healthy controls.

PATIENTS AND METHODS

Forty-four patients with classical PKU were included in the study (21 male, 23 female; aged 0-41 years; mean ± SEM: 16.5 ± 1.7 years). Forty-eight healthy subjects (HS) aged 9-68 years (29.4 ± 2.6 years) comprised the control group, of whom 21 were male and 27 female. Among PKU patients 25 had normal Phe blood concentrations and in 19 they were elevated. In all subjects calprotectin stool concentrations were assessed (PhiCal ELISA, Calpro, Lysaker, Norway).

RESULTS

Normal FC (fecal calprotectin) concentrations were found in 43 (97.7%) PKU patients and 46 (95.8%) HS. No correlation between dietary control of Phe blood concentrations and FC levels in PKU patients was found.

CONCLUSIONS

No detectable intestinal inflammation occurs in phenylketonuria. Lack of dietary control and elevated Phe levels do not seem to be risk factors for inflammation of the mucosa of the gut.

Microencapsulated sodium butyrate reduces the frequency of abdominal pain in patients with irritable bowel syndrome

AIM

Abdominal pain, defaecation disorder and change of bowel habit are the commonest symptoms of irritable bowel syndrome (IBS). The effect of microencapsulated sodium butyrate (MSB) was assessed on the severity of symptoms in patients with IBS.

METHOD

Sixty-six patients treated with one of the standard pharmacological therapies for at least 3 months were included in the study. They were randomized to receive MSB as a supplemental treatment to standard therapy or to receiving a placebo. Previous pharmacological therapy was continued throughout the study in both arms. Clinical evaluation was performed at baseline, 4 and 12 weeks. Each assessment was documented by a validated visual analogue score questionnaire measuring the severity of selected clinical symptoms, a closed-end questionnaire measuring the frequency of selected clinical symptoms and a single closed-end question measuring the subjective improvement of symptoms.

RESULTS

After 4 weeks there was a significant decrease of pain during defaecation in the MSB group which extended to improvement of urgency and bowel habit at 12 weeks. Reduction of abdominal pain, flatulence and disordered defaecation was not statistically significant.

CONCLUSIONS

MSB as a supplemental therapy can reduce the frequency of selected clinical symptoms in patients with IBS, without significant influence on reducing symptom severity.

Pouchitis may increase the risk of dysplasia after restorative proctocolectomy in patients with ulcerative colitis

AIM

Dysplasia of the pouch mucosa after restorative proctocolectomy is rare. The aim of this study was to establish whether there is a correlation between pouchitis and dysplasia.

METHOD

A group of 276 patients treated for ulcerative colitis by restorative proctocolectomy between 1984 and 2009 was analysed. The presence or absence of pouchitis and dysplasia within the pouch was evaluated.

RESULTS

Inflammation was diagnosed in 66 (23.9%) patients, low-grade dysplasia in five (1.8%), high-grade dysplasia in three (1.1%), and cancer in one patient (0.4%). The prevalence of low-grade dysplasia was significantly higher in patients with inflammation than in those without (P < 0.04). High-grade dysplasia was significantly more frequent in pouchitis than in non-inflamed pouches (P < 0.01). Logistic regression analysis suggested that the occurrence of mucosal inflammation increased the risk of low grade dysplasia.

CONCLUSION

Patients with chronic pouchitis are at risk of dysplasia and require surveillance of the pouch.

CCK-B/gastrin receptors in human colorectal cancer

BACKGROUND

Mature amidated gastrin (G17 amide) mediates its effects in the gastrointestinal tract by activating G protein-coupled CCK-B/gastrin receptors. Although trophic actions of gastrin on the gastric mucosa have been well-established, the effect of G17 amide, progastrin and intermediates to colon neoplasia in humans is controversial. While epidemiological evidence from patients with elevated serum gastrin levels related to pernicious anaemia does not support an increased risk for colon cancer, a recent study suggests that prolonged hypergastrinaemia is associated with an increased risk for colon cancer. The extent to which trophic actions of gastrin in colorectal cancer are mediated by functional gastrin receptors remains to be defined. The aim of the present study was to determine CCK-B/gastrin receptor expression, structure, and function in 79 patients with colon cancer.

MATERIALS AND METHODS

CCK-B/gastrin receptor cDNAs were isolated from 79 human colorectal cancer specimens and 15 control tissues, subcloned into the eukaryotic expression vector pCR3.1 and subjected to DNA sequence analysis. Wild-type and mutant cDNAs were transiently expressed in COS-7 cells to determine ligand affinities by 125I-labelled CCK-8S competition binding. Activation of the MAP kinase signalling cascade by G17 amide was determined in transfected Colo 320 cells expressing the wild-type or mutant CCK-B/gastrin receptors. Clonal expansion of single cells was quantified in transfected Colo 320 cells.

RESULTS

Gastrin mRNA is expressed in 44% of colorectal cancers and in 13% of control tissues. CCK-B/gastrin receptor mRNA is expressed in 38% of colorectal cancers and 13% of normal colonic tissue. Co-expression of gastrin and CCK-B/gastrin receptor message is significantly increased in colorectal cancer specimens (32% vs. 0%). There is no correlation between CCK-B/gastrin receptor expression and disease stage or histological grading. DNA sequence analysis revealed one spontaneous CCK-B/gastrin receptor mutation within the third intracellular loop with an exchange of valine-287 for phenylalanine. Pharmacological characterisation of the 287V --> F CCK-B/gastrin receptor reveals wild-type affinities for G17 amide, glycine-extended gastrin, CCK-8S and L-365,260. Mutation 287V --> F is associated with a loss of gastrin-induced MAPK p44/p42 signalling in Colo 320 cells while clonal expansion from single cells is increased by 53.1 +/- 15.9% when compared to Colo 320 cells expressing wild-type CCK-B/gastrin receptors.

CONCLUSIONS

Structural alterations of CCK-B/gastrin receptors may account for increased growth-promoting effects of amidated gastrins in colorectal cancer.

CCK-B/gastrin receptors in human colorectal cancer

BACKGROUND

Mature amidated gastrin (G17 amide) mediates its effects in the gastrointestinal tract by activating G protein-coupled CCK-B/gastrin receptors. Although trophic actions of gastrin on the gastric mucosa have been well-established, the effect of G17 amide, progastrin and intermediates to colon neoplasia in humans is controversial. While epidemiological evidence from patients with elevated serum gastrin levels related to pernicious anaemia does not support an increased risk for colon cancer, a recent study suggests that prolonged hypergastrinaemia is associated with an increased risk for colon cancer. The extent to which trophic actions of gastrin in colorectal cancer are mediated by functional gastrin receptors remains to be defined. The aim of the present study was to determine CCK-B/gastrin receptor expression, structure, and function in 79 patients with colon cancer.

MATERIALS AND METHODS

CCK-B/gastrin receptor cDNAs were isolated from 79 human colorectal cancer specimens and 15 control tissues, subcloned into the eukaryotic expression vector pCR3.1 and subjected to DNA sequence analysis. Wild-type and mutant cDNAs were transiently expressed in COS-7 cells to determine ligand affinities by 125I-labelled CCK-8S competition binding. Activation of the MAP kinase signalling cascade by G17 amide was determined in transfected Colo 320 cells expressing the wild-type or mutant CCK-B/gastrin receptors. Clonal expansion of single cells was quantified in transfected Colo 320 cells.

RESULTS

Gastrin mRNA is expressed in 44% of colorectal cancers and in 13% of control tissues. CCK-B/gastrin receptor mRNA is expressed in 38% of colorectal cancers and 13% of normal colonic tissue. Co-expression of gastrin and CCK-B/gastrin receptor message is significantly increased in colorectal cancer specimens (32% vs. 0%). There is no correlation between CCK-B/gastrin receptor expression and disease stage or histological grading. DNA sequence analysis revealed one spontaneous CCK-B/gastrin receptor mutation within the third intracellular loop with an exchange of valine-287 for phenylalanine. Pharmacological characterisation of the 287V --> F CCK-B/gastrin receptor reveals wild-type affinities for G17 amide, glycine-extended gastrin, CCK-8S and L-365,260. Mutation 287V --> F is associated with a loss of gastrin-induced MAPK p44/p42 signalling in Colo 320 cells while clonal expansion from single cells is increased by 53.1 +/- 15.9% when compared to Colo 320 cells expressing wild-type CCK-B/gastrin receptors.

CONCLUSIONS

Structural alterations of CCK-B/gastrin receptors may account for increased growth-promoting effects of amidated gastrins in colorectal cancer.

Functional expression of HGF and its receptor in human colorectal cancer

BACKGROUND

Hepatocyte growth factor (HGF) stimulates proliferation, migration and morphogenesis of epithelial cells by specific binding to its receptor c-met. Overexpression of HGF or c-met has been reported for human gastric or pancreatic cancer. In colorectal cancer overexpression of c-met but not HGF has been shown. However, elevated HGF serum levels have been detected in colorectal cancer patients. Therefore, the present study was performed to investigate expression patterns of both c-met and HGF in colorectal cancers and metastasis in comparison to normal mucosa. Furthermore, the mitogenic actions of HGF on colorectal cancer cells were studied in vitro.

METHODS

Expression of c-met and HGF were analyzed by RT-PCR and Western blotting and localized in the tissues utilizing immunohistochemistry. Mitogenic effects of HGF were determined in four human colon cancer cell lines by (3)H-thymidine incorporation studies.

RESULTS

C-met and HGF mRNA were detectable in 60% of the normal specimen, but in the majority of cancer samples, and in just 33% of the liver metastasis. In cancer samples a coexpression of c-met and HGF was detected in 77% of the specimens. The extent of protein expression of receptor and ligand correlated with the mRNA expression. Moreover, c-met protein expression was increased 2- to 3-fold in colorectal cancers. C-met was detected in cells of epithelial origin, whereas HGF was expressed by mesenchymal cells. In vitro, HGF significantly stimulated cell growth in all four cell lines.

CONCLUSION

Overexpression of c-met protein in colorectal cancers is combined with an expression of HGF in the majority of cases suggesting a paracrine manner of growth enhancement, while only a weak expression of c-met or HGF was detected in metastatic tissues.

Endoscopical and histological aspects of inflammatory changes in J-pouch mucosa

The aim of the study was endoscopic and histological evaluation of mucosal inflammatory changes in the ileal reservoir after restorative proctocolectomy with ileoanal anastomosis (IPAA) because of FAP (27 patients) and ulcerative colitis (34 patients). Endoscopic symptoms of pouchitis (edema, granularity, contact bleeding, loss of vascular pattern, mucus, erosions) were found in 13 patients (4 were operated on because of FAP, 9 because of UC). A statistically significant difference (p < 0.0001) was found between endoscopic inflammatory index in UC (4.0 +/- 0.5) and in FAP (1.00 +/- 0.00). The endoscopic changes were correlated with the Moskowitz histological classification, in 12 acute score and in 6 chronic score were above 4 points. In 18 patients histological diagnosis of pouchitis was made (5 in FAP, 13 in UC). Acute pouchitis occurred in 12 patients and chronic in 6. In one patient histological changes resembled Crohn's disease. Regular endoscopic control with histological examination and verification of inflammatory lesions in the ileal reservoir is necessary.

Expression of keratinocyte growth factor and its receptor in colorectal cancer

BACKGROUND AND AIMS

The mesenchymal derived keratinocyte growth factor stimulates growth, differentiation and migration of intestinal epithelial cells. In the human gastrointestinal tract an overexpression of this growth factor has been reported in inflammatory bowel disease and pancreatic cancer. In the present study we investigated expression patterns of keratinocyte growth factor and receptor in normal and neoplastic colonic mucosa and in metastases. Furthermore, biological effects on normal intestinal and colorectal cancer cell lines were determined.

MATERIALS AND METHODS

Expression patterns were analysed at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. Localization of ligand and receptor in normal intestinal mucosa and cancer tissue was investigated by immunohistochemistry. Mitogenic effects of keratinocyte growth factor were assayed by [3H]thymidine incorporation in normal (Intestine-407, IEC-6, IEC-18) and colorectal cancer cell lines (Colo320, LoVo, SW403, SW707).

RESULTS

mRNA expression of keratinocyte growth factor and receptor was detected in the majority of normal and cancer samples without significant alterations. At the protein level keratinocyte growth factor expression did not differ between normal and malignant specimens, whereas protein expression of the receptor was increased up to twofold in well- to moderately differentiated colorectal cancers. DNA synthesis was significantly stimulated by keratinocyte growth factor in all three normal intestinal cell lines, whereas this growth factor did not significantly alter the [3H]thymidine incorporation in the colorectal cancer cell lines.

CONCLUSION

Keratinocyte growth factor and its receptor were detected in the majority of samples from normal and neoplastic colonic mucosa, with an overexpression of the receptor seen in the more differentiated tumour samples. Keratinocyte growth factor is a strong mitogen for normal intestinal cells, whereas it is less effective in neoplastic cells.

The influence of partial gastrectomy on the ultrastructural changes in the liver--an experimental animal model

The aim of our studies was to evaluate the ultrastructural changes in the liver in rats after partial gastrectomy. The studied group consisted of 19 Wistar strain rats. In 15 animals partial gastrectomy was done. The control group underwent laparotomy, only. All tissue material was fixed and then prepared in a routinous way for histological and electron microscopy studies. During histological examinations no abnormalities were found. On the ultrastructural level (in tissue samples taken from animals, no more then 4 months after gastrectomy) we found mitochondrial degeneration, vacuolization of cytoplasm, abnormalities in the nuclei and increased activity of B-K cells. The focal necrosis of the hepatocytes was also observed. In tissue samples from animals after 4 to 12 months after primary operation we found increasing number and size of lipid vacuoles in the cytoplasm of hepatocytes The number of Ito cells increased, also. The gastrectomy caused only minimal ultrastructural changes in the liver tissue within the period of observation. Those changes described above may result from numerous metabolic derangements found after gastrectomy.

The level of MAP kinase activity in the stomach stump in rats after subtotal gastrectomy

MAPK (Mitogen-Activated Protein Kinase) is one of the elements of kinase cascades (MAPK, MEK-MAP kinase, kinase, Raf-1, Ras) regulating cellular proliferation and differentiation processes. It seems that the changes in its number and activity may be the factor having influence on carcinogenesis. In some human carcinomas a significant increase of its activity is observed, in others a decrease of its activity is described. Our research aimed at the evaluation of the dynamics of precancerous and cancerous changes in the stomach stump in rats after the experimental, partial stomach resection. Apart from histological and ultrastructural examination we also determined the activity of the sub-unit p42 MAP kinase. The material comprised segments of gastric mucosa of the stomach stump of 15 rats after subtotal gastrectomy. Part of the rats after the procedure were administered carcinogen orally (MNNG). On the histological and ultrastructural examination we used routine methods, the activity of MAP kinase was determined by western-blotting method with the use of IgG against MAPK p42, Santa Cruz #154). In 8 examined rats we observed the increase of MAP kinase activity. We established probable correlation (without statistical analysis, regarding miserly material) between the increase of MAPK activity and histological and ultrastructural changes. Among three cases diagnosed as adenoma tubulare in two we observed the increase of MAPK activity. A clear increase of this kinase was also present in the stomach stump of a rat, which was diagnosed as adenocarcinoma. On the basis of our research carried so far we think that the increase of the MAPK activity may be one of the causes of the neoplasm development. It seems important to obtain the confirmation of our results and to establish a possible usefulness of MAPK activity determination as a prognostic indicator in case of the neoplasm of stomach stump.

Ultrastructural changes in the small bowel epithelium after total gastrectomy

The purpose of the study was to analyze ultrastructural changes in the small bowel mucosa in patients after total gastrectomy. We studied mucosal specimens obtained from 25 patients during control gastroscopy. The specimens were routinely processed for examination in transmission electron microscopy. Early after the operation (up to 6 months) we observed marked inflammatory reaction, disordered architecture of the small bowel mucosa epithelium, the presence of dysplasia-like changes and foci of dysplasia. Later on the structure of the mucosa returned to normality. Only a few dysplastic changes were seen. No relationship was found between altered epithelial structure and type of operation. In conclusion, the epithelium of the small bowel does not transform to a gastric type epithelium.