Adenomatous Colon Polyps in Diabetes: Increased Prevalence in Patients with Chronic Kidney Disease and Its Association with Parathyroid Hormone.

Previous studies have shown a higher prevalence of malignancy in patients with diabetes mellitus (DM) and chronic kidney disease (CKD). The purpose of this study was to investigate the prevalence of adenomatous colon polyps (ACP) as they occur in subjects with DM and coexisting CKD. This is a retrospective cohort study of patients with DM (n=565) who had undergone colonoscopy between 2000-2010. The cohort was further bifurcated into those with CKD (n=296) and those with normal renal function (n=269). Presence or absence of ACP was measured in both groups. Concentrations of serum parathyroid hormone (PTH), Calcium (Ca), and phosphorous (P) were recorded for the CKD group. The levels of these variables in patients with ACP (n=171) were compared with the levels from those without ACP (n=175). Nonparametric statistical methods were applied with statistical significance suggested by p<0.05 (two-sided). The presence of CKD in this cohort demonstrated a significant association with ACP (OR: 2.96; 95% CI: 2.02 to 4.34; p<0.0001). We did not detect a statistically significant difference in P or Ca between the groups. There was, however, a statistically significant difference in PTH; for the group with ACP, PTH: 387.7±351.3 ng/L vs. 172.2±196.7 ng/L; p<0.0001. This data suggests that CKD is associated with ACP in subjects with DM and those with ACP exhibit higher PTH levels when compared to those without ACP.

n-3 polyunsaturated fatty acids reverse the development of polyps in Apc(Min/+) transgenic mice.

Dietary n-3 polyunsaturated fatty acids (n-3 PUFAs) have been demonstrated to reduce tumor load in Apc(Min/+) mice, supporting a role for n-3 PUFAs in the inhibition of colon carcinogenesis and progression. The aim of the present study was to investigate whether a diet enriched with n-3 PUFAs, known already to have anti-neoplastic efficacy in Apc(Min/+) mice, would reverse the development of intestinal polyps. For this purpose, Apc(Min/+) mice were randomly divided into 3 groups of 5 animal each and fed as follows: control ST1 and ST2 groups, received a purified AIN-93M standard diet for 5 and 10 weeks, respectively; the OM-3R group received a purified AIN-93M standard diet for 5 weeks and a diet supplemented with salmon oil, rich in n-3 PUFAs, for another 5 weeks. After dietary treatment, in intestinal tissue, we evaluated the polyp number and volume, expression levels of cell proliferation- and apoptosis-related proteins, as well as the protein expression of LDL receptor and the levels of fatty acid synthase (FAS) activity. The results showed the ability of a diet enriched with n-3 PUFAs to suppress intestinal polyps in Apc(Min/+) mice, and to significantly reverse polyp development associated with the downregulation of cell proliferation markers and with the induction of estrogen receptor ß and LDL receptor, which are negative modulators of cellular proliferation. This noteworthy finding is important for a translational study evaluating the therapeutic role of n-3 PUFAs in the prevention and treatment of subjects with gastrointestinal diseases.

Phytoestrogens/insoluble fibers and colonic estrogen receptor ß: randomized, double-blind, placebo-controlled study.

AIM: To assess the safety and effect of the supplementation of a patented blend of dietary phytoestrogens and insoluble fibers on estrogen receptor (ER)-ß and biological parameters in sporadic colonic adenomas. METHODS: A randomized, double-blind placebo-controlled trial was performed. Patients scheduled to undergo surveillance colonoscopy for previous sporadic colonic adenomas were identified, and 60 eligible patients were randomized to placebo or active dietary intervention (ADI) twice a day, for 60 d before surveillance colonoscopy. ADI was a mixture of 175 mg milk thistle extract, 20 mg secoisolariciresinol and 750 mg oat fiber extract. ER-ß and ER-α expression, apoptosis and proliferation (Ki-67 LI) were assessed in colon samples. RESULTS: No adverse event related to ADI was recorded. ADI administration showed a significant increases in ER-ß protein (0.822 ± 0.08 vs 0.768 ± 0.10, P = 0.04) and a general trend to an increase in ER-ß LI (39.222 ± 2.69 vs 37.708 ± 5.31, P = 0.06), ER-ß/ER-α LI ratio (6.564 ± 10.04 vs 2.437 ± 1.53, P = 0.06), terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (35.592 ± 14.97 vs 31.541 ± 11.54, P = 0.07) and Ki-67 (53.923 ± 20.91 vs 44.833 ± 10.38, P = 0.07) approximating statistical significance. A significant increase of ER-ß protein (0.805 ± 0.13 vs 0.773 ± 0.13, P = 0.04), mRNA (2.278 ± 1.19 vs 1.105 ± 1.07, P < 0.02) and LI (47.533 ± 15.47 vs 34.875 ± 16.67, P < 0.05) and a decrease of ER-α protein (0.423 ± 0.06 vs 0.532 ± 0.11, P < 0.02) as well as a trend to increase of ER-ß/ER-α protein in ADI vs placebo group were observed in patients without polyps (1.734 ± 0.20 vs 1.571 ± 0.42, P = 0.07). CONCLUSION: The role of ER-ß on the control of apoptosis, and its amenability to dietary intervention, are supported in our study.

Low colonocyte folate is associated with uracil misincorporation and global DNA hypomethylation in human colorectum.

Low folate status is a risk factor for colon carcinogenesis; mechanisms proposed to account for this relationship include uracil misincorporation into DNA and global DNA hypomethylation. We investigated whether such biomarkers are related to folate status in isolated colonocytes from colonoscopy patients. In cases with adenomatous polyps (n = 40) or hyperplastic polyps (n = 16), colonocytes were isolated from biopsies from the polyp, from a site adjacent to the polyp, and from normal mucosa 10-15 cm distal to the polyp. In polyp-free controls (n = 53), biopsies were taken from ascending, transverse, and descending areas of colon. Within adenoma cases, there was a trend (P-trend < 0.001) of decreasing colonocyte folate (pg/105 cells, mean ± CI) from the site distal to the polyp (16.9 ± 2.4), to the site adjacent to the polyp (14.7 ± 2.3), to the polyp (12.8 ± 2.0). Correspondingly, there were increases in uracil misincorporation (P-trend < 0.001) and global DNA hypomethylation (P-trend = 0.012) across the 3 sites. Colonocyte folate concentrations were significantly correlated with RBC folate concentrations, but only in individuals with generally lower (≤484 µg/L) RBC folate status (r = 0.54; P = 0.006; n = 24), and were also significantly lower in normal mucosa of cases with adenomatous polyps than in controls matched for colonic segment. In conclusion, localized folate deficiency in specific areas of colon might create carcinogenic fields and affect the development of colorectal polyps through uracil misincorporation and DNA hypomethylation; alternatively, the polyp itself might deplete folate in the surrounding tissue. Folate supplementation trials aimed at colon cancer prevention should target individuals with suboptimal folate status.

Association between folate levels and CpG Island hypermethylation in normal colorectal mucosa.

Gene-specific promoter methylation of several genes occurs in aging normal tissues and may predispose to tumorigenesis. In the present study, we investigate the association of blood folate levels and dietary and lifestyle factors with CpG island (CGI) methylation in normal colorectal mucosa. Subjects were enrolled in a multicenter chemoprevention trial of aspirin or folic acid for the prevention of large bowel adenomas. We collected 1,000 biopsy specimens from 389 patients, 501 samples from the right colon and 499 from the rectum at the follow-up colonoscopy. We measured DNA methylation of estrogen receptor alpha (ERα) and secreted frizzled related protein-1 (SFRP1), using bisulfite pyrosequencing. We used generalized estimating equations regression analysis to examine the association between methylation and selected variables. For both ERα and SFRP1, percentage methylation was significantly higher in the rectum than in the right colon (P = 0.001). For each 10 years of age, we observed a 1.7% increase in methylation level for ERα and a 2.9% increase for SFRP1 (P < 0.0001). African Americans had a significantly lower level of ERα and SFRP1 methylation than Caucasians and Hispanics. Higher RBC folate levels were associated with higher levels of both ERα (P = 0.03) and SFRP1 methylation (P = 0.01). Our results suggest that CGI methylation in normal colorectal mucosa is related to advancing age, race, rectal location, and RBC folate levels. These data have important implications regarding the safety of supplementary folate administration in healthy adults, given the hypothesis that methylation in normal mucosa may predispose to colorectal neoplasia.

Clock genes and cancer.

Period genes ( Per2, Per1) are essential circadian clock genes. They also function as negative growth regulators. Per2 mutant mice show de novo and radiation-induced epithelial hyperplasia, tumors, and an abnormal DNA damage response. Human tumors show Period gene mutations or decreased expression. Other murine clock gene mutations are not associated with a tumor prone phenotype. Shift work and nocturnal light exposure are associated with circadian clock disruption and with increased cancer risk. The mechanisms responsible for the connection between the circadian clock and cancer are not well defined. We propose that circadian disruption per se is not uniformly tumor promoting and the mechanisms for tumor promotion by specific circadian clock disturbances will differ dependent upon the genes and pathways involved. We propose that Period clock gene mutations promote tumorigenesis by unique molecular pathways. Per2 and Per1 modulate beta-catenin and cell proliferation in colon and non-colon cancer cells. Per2 mutation increases intestinal beta-catenin levels and colon polyp formation. Per2 mutation also increases Apc(Min/+)-mediated intestinal and colonic polyp formation. Intestinal tumorigenesis per se may also alter clock function as a result of increased beta-catenin destabilizing PER2 protein. Levels and circadian rhythm of PER2 in Apc(Min/+) mouse intestine are markedly decreased, and selective abnormalities in intestinal clock gene and clock-controlled gene expression are seen. We propose that tumor promotion by loss of PERIOD clock proteins is unique to these clock genes as a result of altered beta-catenin signaling and DNA damage response. PERIOD proteins may offer new targets for cancer prevention and control.

Selenium, copper, and zinc concentrations in intestinal cancer tissue and in colon and rectum polyps.

The prospective randomized trial was used to determine Se, Zn, and Cu concentrations in intestinal cancer tissue and colorectal polyp. We also determined the relationship among the trace element levels in cancer tissue, the localization of neoplasms, and the stage of their development. The concentrations of these trace elements were examined in cancer tissue of the colorectum in 67 patients and in the colon and rectum polyps in 42 patients using the total-reflection X-ray fluorescence (TRXRF) method. The mean concentration of Se in colorectal cancer was 0.86 microg/g tissue and was statistically higher than in the case of polyps (0.57 microg/g). The mean concentration of Zn in colorectal cancer was higher than in the polyp (14.8 microg/g and 9.84 microg/g, respectively). The determined average concentration of Cu in colorectal cancer was 3.87 microg/g tissue and was a little lower than the level of this metal in the polyp (3.94 microg/g). There was no difference in the levels of these trace elements depending on the location of the neoplasm and the stage of its development. Also, there was no difference between the concentrations of these trace elements in the cancer tissue of malignant and benign tumors after taking into consideration the sex and age of patients. During the examination, we determined significantly higher concentrations of only selenium and zinc in the cancer tissue and not in the polyp. The level of copper was lower in a malignant tumor than in a benign one.

The effect of high doses of folic acid on the overexpression of ornithine decarboxylase and S-adenosylmethionine content in human colon adenomatous polyps.

It was shown that the 3-month supplementation of patients having colon polyps with folic acid (5 mg/day) led to a 35% decrease in abnormally high ornithine decarboxylase activity in polyps that was accompanied by a 43% increase of S-adenosylmethionine content in polyps.

The relationship between faecal bile acid profile with or without supplementation with calcium and antioxidants on recurrence and growth of colorectal polyps.

Faecal bile acids (FBA) have been implicated in colon carcinogenesis. The results of case-control studies of colorectal cancer and polyp patients are, however, conflicting. The aim of this study was to examine the influence of faecal bile acids on occurrence, growth and recurrence of colorectal polyps, and to see if a mixture of calcium and antioxidants might possibly act on cancer precursors through the effect on FBA. A total of 116 polyp-bearing patients were recruited from the outpatients department. Polyps < 10 mm in diameter were left in situ and measured by annual colonoscopy for 3 years. The patients received placebo or a mixture of antioxidants and calcium carbonate, 1.6 g calcium ion daily. Faecal samples were collected annually; the first, 1 month after start of intervention, freeze dried and subjected to bile acid profile analysis. Two age and sex matched control groups were recruited (n = 35), one from healthy volunteers (healthy controls) and one from the outpatients referred for colonoscopy, with no polyps (hospital controls). Twelve of 47 patients from the healthy volunteers had polyps (healthy polyp patients). One or more adenomas were found in 93 patients. The faeces of the hospital controls had significantly higher concentrations of total and secondary bile acids than did the healthy controls. There was no difference in FBA profile between the polyp group and the hospital controls, but significantly higher concentration of total and secondary faecal bile acids in the healthy polyp patients compared with the healthy control group (P < 0.05). No increased concentration of FBA were found in the polyp patients with multiple polyps (n = 21) or previous treatment for colorectal cancer (n = 7). No associations between FBA profile and growth or recurrence of colorectal polyps were found. The polyp patients receiving active medication had higher faecal concentrations of total and secondary bile acids in the beginning of the study than at the end, in spite of a good compliance. The present study does not support bile acids as being important markers of initiation or growth of small and medium sized colorectal adenomas. In the present study the calcium and antioxidants did not seem to affect the growth or recurrence of colorectal adenomas by increased TBA excretion in the faeces.

Effect of folate supplementation on DNA methylation of rectal mucosa in patients with colonic adenomas: correlation with nutrient intake.

We have evaluated the effect of folate supplementation (5 mg/day) on global deoxyribonucleic acid (DNA) methylation status of the rectal mucosa of 20 patients with resected colonic adenomas in a prospective, controlled, cross-over study. Baseline values of DNA methylation were inversely correlated with caloric (P = 0.03) and fat intake (P = 0.05) and patients harbouring multiple polyps consumed significantly more calories (P = 0.0006), fat (P = 0.009) and carbohydrates (P = 0.009) as compared to patients having one single lesion. Folate supplementation resulted in a significant decrease of DNA hypomethylation in 7/20 patients (P = 0.05) which returned to previous values after placebo treatment. This effect was significantly correlated with number of polyps, with all the responders presenting one single lesion, whereas 8/13 of the non-responders had multiple ones (chi2 = 7.17, P = 0.007). In conclusion, folate supplementation may decrease degree of DNA hypomethylation, but only in patients with one single polyp. In those with multiple lesions, other nutritional factors such as caloric and fat intake, may be more determinant.

Accumulation of beta-carotene in normal colorectal mucosa and colonic neoplastic lesions in humans.

The quantity of beta-carotene (BC) accumulated in colonic polyps and colonic cancerous tissue in humans in situ was determined relative to the quantity accumulated in normal colon and rectal tissue. Serum concentration of BC, retinol, and alpha-tocopherol and tissue BC concentration were determined by high-performance liquid chromatography in samples obtained before and after oral supplementation with BC (30 mg/day). The serum BC and retinol concentrations significantly increased in response to supplementation in control, polyp, and cancer patients, but there was no change in serum alpha-tocopherol concentration. The BC concentration in tissue (colon, rectum, and tumor) of cancer patients was significantly less than that in tissue samples from control and polyp patients. Relative to baseline values, BC accumulated to a significant extent in tissues from all patients, including polyp and tumor tissue, during supplementation. The results indicate that BC does accumulate in colonic neoplastic tissue in humans and may potentially be utilized to augment cytotoxicity of chemotherapeutics or to prevent malignant transformation of cells.

Effects of oral calcium supplementation on intestinal bile acids and cytolytic activity of fecal water in patients with adenomatous polyps of the colon.

Calcium has been proposed to prevent colon cancer in subjects at risk for this tumour. This effect is supposed to be due at least in part to binding the bile acids to calcium, making them insoluble and harmless. To evaluate the effects of oral calcium supplementation on intestinal bile acids, 19 patients with adenomatous colonic polyps were supplemented with 35.5 mmol Ca2+ daily for 12 weeks. Duodenal bile, 24-h feces and 24-h urine were collected before and at the end of the 12-week period. In duodenal bile proportional concentration of cholic acid increased (38 +/- 4 vs. 51 +/- 3%, P < 0.001), whereas that of chenodeoxycholic acid decreased (35 +/- 3 vs. 25 +/- 2%, P < 0.01). Total fecal bile acid excretion increased (950 +/- 126 vs. 1218 +/- 137 mumol 24 h-1, P < 0.01), with proportional concentrations of the main primary and secondary bile acids remaining the same. Cytolytic activity of fecal water, measured by the degree of lysis of erythrocytes by the water, decreased (45 +/- 8 vs. 30 +/- 7%, P < 0.05). Total excretion of calcium increased as expected from the supplementary dose. It is concluded that calcium supplementation markedly affects intestinal bile acids and lytic activity of fecal water and that, in view of similar results during 1-week calcium supplementation in young healthy subjects, these effects remain constant over at least 3 months and occur both in healthy persons and in patients at increased risk for colon cancer.

Fecal ammonia in patients with adenomatous polyps and cancer of the colon.

The correlation between high intakes of protein and high incidence of human colonic cancer is unexplained. Appreciable amounts of ammonia are generated in the large bowel through bacterial degradation of proteins and peptides, and experimental studies indicate that ammonia may select for neoplastic growth. Fecal concentrations of ammonia did not differ among 17 patients with former colonic adenomas [40.6 +/- 4.5 (SE) mM], 17 patients with former colonic cancer (51.4 +/- 3.9 mM), and 16 healthy controls (46.4 +/- 6.1 mM). By use of an in vitro fecal incubation system, possible alterations in bacterial fermentation and formation of ammonia were investigated. Fecal suspensions were incubated for 6 and 24 hours with and without addition of fermentable substrates (ispaghula husk, wheat bran, albumin, and glucose; 10 mg/ml). The in vitro production of ammonia in unsupplemented fecal homogenates from both groups of patients was comparable with the production found in homogenates from healthy controls, and the response to fermentable substrates was similar in all three groups. Addition of albumin caused a marked increase in the production of ammonia, and addition of glucose increased bacterial assimilation of ammonia considerably. These well-known characteristics of bacterial metabolism of ammonia apparently did not differ between healthy individuals and patients investigated more than three months after colonoscopic polypectomy or colonic cancer resection.

Short chain fatty acid distributions of enema samples from a sigmoidoscopy population: an association of high acetate and low butyrate ratios with adenomatous polyps and colon cancer.

We investigated the distribution of short chain fatty acids (SCFA) in enema samples taken from subjects before sigmoidoscopy as an indicator of possible microbial community differences between subjects subsequently diagnosed as normal or having colonic disorders. The major SCFA in all groups were acetic, propionic, and butyric acids. A significantly higher ratio of acetate to total SCFA and lower ratio of butyrate to total SCFA was found for polyp-colon cancer subjects than for normal subjects. There were no significant differences in the ratios of acetate, propionate, or butyrate between the diverticulosis or inflammatory bowel groups and the normal group. There were no significant sex differences nor were there correlations with the ratios of acetate, propionate or butyrate and age, subject weight, or dry weights of samples. Significant differences in concentrations of individual acids were found between normal and certain diagnostic groups. The difference in proportions of individual SCFA between groups suggest differences in fermentation patterns of the colonic microflora.

Super-efficient starch absorption. A risk factor for colonic neoplasia?

We tested the hypothesis that super-efficient starch absorption, by reducing the supply of carbohydrate to the colon, may be associated with and possibly promote colonic neoplasia. By means of breath hydrogen measurements following a potato meal and comparison with the hydrogen response to lactulose, the amount of starch escaping small bowel absorption was measured in 10 patients who had a colonic adenoma removed endoscopically and in 10 controls. The subjects' consumption of starch and fiber was assessed. Percentage unabsorbed starch was approximately half as much in the patients (5.3%) compared with the controls (10.9%, P less than 0.05). Consumption of starch and dietary fiber, and mouth-to-cecum transit times were not significantly different. Unabsorbed starch was calculated to contribute to 6.0 g/day colonic carbohydrate in the patients and 10.9 g/day in the controls (P less than 0.05). This study confirms that unabsorbed starch provides an important quantity of colonic carbohydrate and suggests that super-efficient starch absorption, by reducing this provision, may promote colonic neoplasia.

Bowel preparation and the risk of explosion during colonoscopic polypectomy.

Concentration of oxygen, methane, and hydrogen were measured in intracolonic gas samples aspirated through the colonoscope at the time of colonoscopy from 46 patients. Of the above patients 20 prepared either with mannitol (n = 10) or with castor oil (n = 10) had the instrument passed to the caecum without air insufflation or suction. After mannitol, mean intracolonic hydrogen concentration (4.07%) was significantly higher (p less than 0.001) than after castor oil (0.51%). Mean oxygen and methane concentrations were approximately similar. Potentially explosive concentrations of hydrogen (greater than 4.1%) and or methane (greater than 5%) were present in 6/10 patients given mannitol and 2/10 patients given castor oil. Nevertheless only one patient from each group had coexisting oxygen concentrations of more than 5% producing thus a combustile mixture. Routine colonoscopy (using air insufflation and suction) was performed in 26 patients prepared with mannitol. Mean intracolonic hydrogen and methane was 0.63% and 0.88% respectively. The highest recorded concentration of hydrogen was 2.6%, and of methane 2.1%, while all patients had oxygen concentrations of more than 5%. It is suggested, therefore, that routine insufflation and suction before colonoscopic electrosurgical polypectomy should result in safe levels of these gases. The remote possibility of pockets of undiluted gas in explosive concentration, however, indicates the use of an inert gas such as carbon dioxide if mannitol preparation is used before electrosurgery.