Review article: chemoprevention of colorectal cancer

Association of Domestic Water Hardness with All-Cause and Cause-Specific Cancers: Evidence from 447,996 UK Biobank Participants

BACKGROUND

Accumulating evidence suggests that domestic water hardness is linked to health outcomes, but its association to all-cause and cause-specific cancers warrants investigation.

OBJECTIVE

The aim of this study was to investigate the association of domestic hard water with all-cause and cause-specific cancers.

METHODS

In the prospective cohort study, a total of 447,996 participants from UK Biobank who were free of cancer at baseline were included and followed up for 16 y. All-cause and 22 common cause-specific cancer diagnoses were ascertained using hospital inpatient records and self-reported data until 30 November 2022. Domestic water hardness, measured by CaCO 3 concentrations, was obtained from the local water supply companies across England, Scotland, and Wales in 2005. Data were analyzed using Cox proportional hazard models, with adjustments for known measured confounders, including demographic, socioeconomic, clinical, biochemical, lifestyle, and environmental factors.

RESULTS

Over a median follow-up of 13.6 y (range: 12.7-14.4 y), 58,028 all-cause cancer events were documented. A U-shaped relationship between domestic water hardness and all-cause cancers was observed (p for nonlinearity < 0.001 ). In comparison with individuals exposed to soft water (0 - 60 mg / L ), the hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause cancer were 1.00 (95% CI: 0.98, 1.02) for those exposed to moderate hard water (> 60 - 120 mg / L ), 0.88 (95% CI: 0.84, 0.91) for those exposed to hard water (> 120 - 180 mg / L ) and 1.06 (95% CI: 1.04, 1.08) for those exposed to very hard water (> 180 mg / L ). Additionally, domestic water hardness was associated with 11 of 22 cause-specific cancers, including cancers of the esophagus, stomach, colorectal tract, lung, breast, prostate, and bladder, as well as non-Hodgkin lymphoma, multiple myeloma, malignant melanoma, and hematological malignancies. Moreover, we observed a positive linear relationship between water hardness and bladder cancer.

DISCUSSION

Our findings suggest that domestic water hardness was associated with all-cause and multiple cause-specific cancers. Findings from the UK Biobank support a potentially beneficial association between hard water and the incidence of all-cause cancer. However, very hard water may increase the risk of all-cause cancer. https://doi.org/10.1289/EHP13606.

HLA Class I Expression Is Associated with DNA Damage and Immune Cell Infiltration into Dysplastic and Neoplastic Lesions in Ulcerative Colitis

Human leukocyte antigen class I (HLA-I) is considered a genetic pathogen for ulcerative colitis (UC). This study aimed to investigate the significance of DNA damage and HLA-I expression in infiltrating immune cells and immune checkpoint protein PD-L1 expression in dysplasia/colitic cancer (CC) and sporadic colorectal cancer (SCRC). We performed immunohistochemical staining for HLA-I, PD-L1, γH2AX (DNA damage marker), and immune cell markers such as CD8, FOXP3, CD68, and CD163 (in surgically resected specimens from 17 SCRC patients with 12 adjacent normal mucosa (NM) and 9 UC patients with 18 dysplasia/CC tumors. The ratio of membrane HLA-I-positive epithelial cells in UC and dysplasia/CC tissues was significantly higher than that in NM and SCRC. High HLA-I expression in dysplasia/CC was associated with high positivity of γH2AX and PD-L1 expression compared to SCRC. The infiltration of CD8-positive T cells and CD68-positive macrophages in HLA-I-high dysplasia/CC was significantly higher than in UC and SCRC. Dysplasia/CC specimens with DNA damage exhibited high levels of HLA-I-positive epithelial cells with high CD8- and CD68-positive immune cell infiltration compared to UC and SCRC specimens. Targeting DNA damage in UC may regulate immune cell infiltration, immune checkpoint proteins, and carcinogenesis by modulating DNA damage-induced HLA-I antigen presentation.

Dose-response meta-analysis of coffee consumption and risk of colorectal adenoma

BACKGROUND

The association between coffee and colorectal adenoma risk remains controversial. We conducted a meta-analysis of cohort and case-control studies to sum up the existing proof about this matter.

METHODS

We searched Pubmed, Medline, and Embase for studies published before 1 September 2018 on coffee consumption and colorectal adenoma in any language. The different ORs were calculated for cohort and case-control studies in this study, and we use a random-effects model to aggregate the relative risks of individual studies and conduct dose response, heterogeneity, and publication bias.

RESULTS

A total of 8 studies (6 case-control studies, 2 cohort studies) were identified, including 7090 subjects. In a summary analysis of all studies, high coffee intake (compared the highest with the lowest categories) was associated with a reduced risk of colorectal adenoma (odds ratio [OR] = 0.70, 95% confidence interval [CI] = 0.55-0.90). The results of subgroup analysis of adenoma location were similar with the pooled analysis, except for rectal adenoma. In the dose-response meta-analysis study, the estimated total odds ratio for increasing coffee consumption by 150 ml per day (about one cup) was 0.91 (95% CI = 0.87-0.95).

CONCLUSIONS

The meta-analysis demonstrates possible evidence that increased coffee intake is related to a reduced risk of colon adenoma. However, because of latent confusion and different exposure classification, this finding should be carefully considered.

Simultaneous Assessment of the Efficacy and Toxicity of Marine Mollusc-Derived Brominated Indoles in an In Vivo Model for Early Stage Colon Cancer

The acute apoptotic response to genotoxic carcinogens animal model has been extensively used to assess the ability of drugs and natural products like dietary components to promote apoptosis in the colon and protect against colorectal cancer (CRC). This work aimed to use this model to identify the main chemopreventative agent in extracts from an Australian mollusc Dicathais orbita, while simultaneously providing information on their potential in vivo toxicity. After 2 weeks of daily oral gavage with bioactive extracts and purified brominated indoles, mice were injected with the chemical carcinogen azoxymethane (AOM; 10 mg/kg) and then killed 6 hours later. Efficacy was evaluated using immunohistochemical and hematoxylin staining, and toxicity was assessed via hematology, blood biochemistry, and liver histopathology. Comparison of saline- and AOM-injected controls revealed that potential toxic side effects can be interpreted from blood biochemistry and hematology using this short-term model, although AOM negatively affected the ability to detect histopathological effects in the liver. Purified 6-bromoisatin was identified as the main cancer preventive agent in the Muricidae extract, significantly enhancing apoptosis and reducing cell proliferation in the colonic crypts at 0.05 mg/g. There was no evidence of liver toxicity associated with 6-bromoisatin, whereas 0.1 mg/g of the brominated indole tyrindoleninone led to elevated aspartate aminotransferase levels and a reduction in red blood cells. As tyrindoleninone is converted to 6-bromoisatin by oxidation, this information will assist in the optimization and quality control of a chemopreventative nutraceutical from Muricidae. In conclusion, preliminary data on in vivo safety can be simultaneously collected when testing the efficacy of new natural products, such as 6-bromoisatin from Muricidae molluscs for early stage prevention of colon cancer.

Coffee intake and the risk of colorectal adenoma: The colorectal adenoma study in Tokyo

Coffee is a commonly consumed beverage which contains several potential anticarcinogenic and chemopreventive compounds, and has been hypothesized to have protective effects in colorectal neoplasia. However, the limited available data on coffee consumption in relation to colorectal adenoma (CRA), a precursor lesion to most colorectal cancers, remain largely inconsistent. In this study, we evaluated the association of coffee intake with the risk of CRA in a middle-aged Japanese population. Study subjects were selected from examinees who underwent total colonoscopy as part of a cancer screening program and responded to self-administered dietary and lifestyle questionnaires. A total of 738 patients with adenoma and 697 controls were included in the study. Coffee intake was assessed with a food frequency questionnaire, and divided into quartiles based on the distribution among controls. Unconditional logistic regression models were used to estimate odds ratio (OR) and 95% confidence interval (CI) of CRA, with adjustment for potential confounding factors. High coffee consumption was associated with a reduced risk of CRA, with a multivariate-adjusted OR for the highest versus lowest quartile of coffee intake of 0.67 (95% CI = 0.48-0.93; ptrend  = 0.02). The inverse association of coffee intake was limited to proximal (OR = 0.64; 95%CI = 0.44-0.95; ptrend  = 0.04) and distal colon adenoma (OR = 0.62; 95%CI = 0.39-0.99; ptrend  = 0.06), and appeared to be more evident with small (OR = 0.68; 95%CI = 0.49-0.96; ptrend  = 0.04) and single adenomas (OR = 0.65; 95%CI = 0.44-0.95; ptrend  = 0.02). Green tea intake was not found to be associated with CRA risk. This study provides support for the protective effect of coffee drinking on colon adenomas, a precursor of colon cancer.

Ulcerative colitis: From inflammation to cancer. Do estrogen receptors have a role?

Ulcerative colitis (UC) is a condition at increased risk for colorectal carcinoma (CRC) development. Nowadays, screening and follow-up programs are routinely performed worldwide to promote the early detection of CRCs in subjects with well known risk factors (extent, duration and severity of the disorder). The diffusion of these procedures is presumably the main reason for the marked reduction of cancer incidence and mortality in the course of UC. In addition, chemoprevention has been widely investigated and developed in many medical fields, and aspirin has shown a preventive effect against CRC, while mesalazine has been strongly invoked as a potential chemopreventive agent in UC. However, available studies show some limitations due to the obvious ethical implications of drug withdrawal in UC in order to design a control group. The estrogen receptors (ER) alpha/beta balance seems to have a relevant influence on colorectal carcinogenesis and ER beta appears to parallel apoptosis, and hence an anti-carcinogenic effect. Phytoestrogens are compounds acting as ER beta agonists and have shown a promising chemopreventive effect on sporadic as well as genetically inherited CRC. There is evidence suggesting a role for ERs in UC-related carcinogenesis. In this perspective, since these substances can be considered as dietary supplements and are completely free from side effects, phytoestrogens could be an interesting option for CRC prevention, even when the disease is a consequence of long-term chronic inflammation, as in the course of UC. Further studies of their effects are warranted in both the basic research and clinical fields.

Prevention of colitis-associated cancer: natural compounds that target the IL-6 soluble receptor

The risk of developing colorectal cancer increases in patients with inflammatory bowel disease (IBD) and a growing body of evidence shows the critical role of interleukin (IL-6) in this process. IL-6 is both a pro- and anti-inflammatory cytokine whose effects are mediated through activation of STAT3. Recent studies have also demonstrated that IL-6 trans-signaling through its soluble receptor occurs in IBD and cancer. IL-6 trans-signaling therefore is emerging as an attractive approach to diminish the inflammatory signals in conditions of chronic inflammation. The purpose of cancer chemoprevention is to either delay the onset or progression from precancerous lesions. Natural compounds because of their low toxicity render themselves excellent candidates that can be administered over the lifetime of an individual. With the focus of managing IBD over a long time and preventing onset of colitis-associated cancer, we believe that there should be increased research focus on identifying chemopreventive compounds that can render themselves to long term use possibly for the lifetime of predisposed individuals. Here, we review the role of IL-6 signaling in IBD and colitis-associated cancer and underscore the importance of searching for natural compounds that would target the IL-6 trans-signaling pathway as a way to diminish chronic inflammatory conditions in the gastrointestinal tract and possibly hamper the progression to colon cancer. We propose that effective screening and identification of natural chemopreventive compounds that target IL-6 trans-signaling has important implications for the development of optimal strategies against cancer development triggered by inflammation.

Cancer risk in patients with pyogenic liver abscess: a nationwide cohort study

BACKGROUND

There has been no large-scale population-based study on the relationship between pyogenic liver abscesses (PLA) and subsequent cancer risk.

AIM

To estimate all cancer risk following a diagnosis of PLA.

METHODS

Based on Taiwan's National Health Insurance Research Database, 1257 patients with PLA without prior cancers in the period 1996-2008 were identified and followed-up. The standard incidence ratio (SIR) of each cancer was calculated as the number of observed cancer cases arising among the PLA patients divided by the expected case number of cancer cases according to the national cancer rates.

RESULTS

Of the 1257 PLA patients identified, 598 (47.6%) had diabetes mellitus. After a median (±s.d.) follow-up of 3.33 ± 3.45 years, 186 were diagnosed with cancers, including 56 liver cancer, 22 biliary tract cancer and 40 colorectal cancer patients. Patients with PLA had a higher risk of all cancers (SIR, 3.83; 95% CI, 3.30-4.42), liver cancer (SIR, 7.87; 95% CI, 5.94-10.21), biliary tract cancer (SIR, 34.58; 95% CI, 21.67-52.36) and colorectal cancer (SIR, 5.27; 95% CI, 3.76-7.18). The highest SIRs of all cancers, liver cancer, biliary tract cancer and colorectal cancer occurred within 90 days of follow-up (360.82; 95% CI, 278.46-459.91, 257.28; 95% CI, 186.17-346.56, 1153.38; 95% CI 694.08-1801.24, and 52.63; 95% CI 25.2-96.8 respectively).

CONCLUSIONS

Pyogenic liver abscesses may herald the onset of cancer, especially hepato-biliary and colon cancer. Further surveys should be conducted for the detection of occult cancers in such patients.

Strategies of targeting oral drug delivery systems to the colon and their potential use for the treatment of colorectal cancer

Colorectal cancer (CRC) is the third most common cause of cancer-related death in both men and women. Often, surgical intervention remains the choice in treating CRC. Traditional dosage forms used for treating CRC deliver drug to wanted as well as unwanted sites of drug action resulting in several adverse side effects. Targeted oral drug delivery systems are being investigated to target and deliver chemotherapeutic and chemopreventive agents directly to colon and rectum. Site-specific delivery of a drug to colon increases its concentration at the target site, and thus requires a lower dose with reduced incidence of side effects. The major obstacle to be overcome for successful targeting of drug to colon through oral route is that drug absorption/degradation must be avoided in stomach and small intestine before the dosage form reaches colon. The review includes discussion of physiological factors that must be considered when targeting drugs directly to colorectal region, an outline on drugs used for treatment and prevention of CRC, and a brief description of various types of colon-targeted oral drug delivery systems. The focus is on the assessment of various formulation approaches being investigated for oral colon-specific delivery of drugs used in the treatment and prevention of CRC.

Selenite-induced apoptosis and autophagy in colon cancer cells

Sodium selenite (Se) is known to induce diverse stress responses in malignant cells which may lead to various types of cell death including apoptosis and/or autophagy. In colon cancer cells, Se activates several signaling pathways whose interactions and ultimate endpoints may vary in individual study models. In our previous work we showed differences in Se-dependent growth inhibition, cell cycle alterations and apoptosis in colon cancer cells with functional (HCT-116) and deleted (HCT-116-p53KO) p53. Moreover, detailed morphological and biochemical analyses revealed the presence of autophagy in Se-treated cells. Thus the aim of this study was to investigate in detail mechanisms, relationship and crosstalk between apoptosis and autophagy in Se-treated HCT-116 cancer cells differing in p53 status since p53 has been shown to play a well-known role in apoptosis but dichotomous role in autophagy. We report that the absence of p53 in malignant colonocytes changes patterns of response to Se-induced stress which include differential activation of MAP kinases (p38 - HCT-116 and JNK - HCT-116 p53KO) including their respective roles in the process of apoptosis and autophagy as well as the involvement of mTOR or PI3K signaling. Our results seem to suggest that deletion of p53 inevitably leads to a higher level of instability and delays in an individual cell decision in the face of stress whether to activate apoptosis or autophagy which may consequently occur simultaneously with mutual dichotomous relationship.

Prospective cohort study of soy food intake and colorectal cancer risk in women

BACKGROUND

Soy and some of its constituents, such as isoflavones, have been shown to have cancer-inhibitory activities in experimental studies. Data from epidemiologic studies linking usual soy food intake with colorectal cancer are limited and inconsistent.

OBJECTIVE

The objective was to investigate whether soy food intake is associated with colorectal cancer risk.

DESIGN

We prospectively examined 68,412 women aged 40-70 y and free of cancer and diabetes at enrollment. Usual soy food intake was assessed at baseline (1997-2000) and reassessed during the first follow-up (2000-2002) through in-person interviews with a validated food-frequency questionnaire. We excluded the first year of observation to minimize lifestyle changes related to preclinical disease.

RESULTS

During a mean follow-up of 6.4 y, 321 incident colorectal cancer cases were identified. After adjustment for potential confounding factors, total soy food intake was inversely associated with colorectal cancer risk. Each 5-g/d increment in intake of soy foods as assessed by dry weight [equivalent to approximately 1 oz (28.35 g) tofu/d] was associated with an 8% reduction in risk (95% CI: 3%, 14%). Women in the highest tertile of intake had a multivariate relative risk of 0.67 (95% CI: 0.49, 0.90) compared with those in the lowest tertile (P for trend = 0.008). This inverse association was primarily confined to postmenopausal women. Similar results were also found for intakes of soy protein and isoflavones.

CONCLUSION

This prospective study suggests that consumption of soy foods may reduce the risk of colorectal cancer in postmenopausal women.

Chemoprevention of colorectal cancer: feasibility in everyday practice?

Chemoprevention means the use of agents to prevent, delay, or reverse carcinogenesis. This review was designed to critically discuss the most promising agents in colorectal cancer (CRC) chemoprevention. Aspirin is the best studied chemopreventive agent for CRC. Optimal chemoprevention requires long-term use and high dose of aspirin that may increase the risk of gastrointestinal bleeding. Nonsteroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors may also be candidates for chemoprevention. The regular use of nonsteroidal anti-inflammatory drugs, however, causes adverse effects including gastrointestinal bleeding, and cyclooxygenase-2 inhibitors may increase the risk of cardiovascular events. In patients with ulcerative colitis 5-aminosalicylates reduce the risk of CRC and dysplasia. Ursodeoxycholic acid can reduce the risk of dysplasia or CRC in patients with primary sclerosing cholangitis and ulcerative colitis. Current data are insufficient to support the use of hormone replacement therapy to reduce the risk of CRC. Statins may have chemopreventive effects, but further investigation of their overall benefits in preventing CRC is warranted. Antioxidant supplements cannot prevent CRC. The usefulness of selenium, folate, calcium, and vitamin D awaits further evaluation. Chemoprevention cannot yet be accepted as standard medical practice. Use of chemopreventive agents cannot be a substitute for colorectal surveillance.

Use of non-steroidal anti-inflammatory drug and colorectal polyps: a systematic review and Meta-analysis

AIM: The evaluate the association between use of nonsteroidal anti-inflammatory drugs (NSAIDs) and the risk of colorectal polyps.

METHODS: A fully recursive literature search from 1966 to December 2007 was conducted in PubMed, EMBASE, Cancerlit, ISI and Cochrane Collaboration controlled trials register to identify relevant studies. Summary odds ratios (OR) and 95% confidence intervals (CI) were calculated under a random-effects model.

RESULTS: Thirty nine studies (17 controlled clinical trials, 12 case-control and 10 cohort) were identified. The use of NSAIDs was associated with a statistically significant reduction for the recurrence or occurrence of colorectal polyps in patients with sporadic adenomas, with a summary OR of 0.63 (95%CI: 0.53-0.75, P = 0.37) for randomized controlled trials, 0.70 (95%CI: 0.61-0.80, P = 0.02) for case-control studies, and 0.86 (95%CI: 0.77-0.96, P = 0.02) for cohort studies. Seven controlled clinical trials reported a significant regression and a reduction in the number and size of polyps in patients with familial adenomatous polyposis after NSAIDs treatment. As for the type of drugs, the use of aspirin and non-aspirin NSAIDs demonstrated a similar magnitude of risk reduction. A dose-dependent association between NSAIDs use and the risk reduction of colorectal polyps was confirmed in six randomized controlled trials, three case-control and one cohort studies.

CONCLUSION: Use of NSAIDs is associated with a decreased risk of colorectal polyps in a dose-dependent manner. The findings warrant proper clinical trials to define the optimal dose and duration of treatment, and to balance the risks and benefits of prophylactic use of NSAIDs in specific populations.

De novo ceramide biosynthesis is associated with resveratrol-induced inhibition of ornithine decarboxylase activity

Previous studies could demonstrate, that the naturally occuring polyphenol resveratrol inhibits cell growth of colon carcinoma cells at least in part by inhibition of protooncogene ornithine decarboxylase (ODC). The objective of this study was to provide several lines of evidence suggesting that the induction of ceramide synthesis is involved in this regulatory mechanisms. Cell growth was determined by BrdU incorporation and crystal violet staining. Ceramide concentrations were detected by HPLC-coupled mass-spectrometry. Protein levels were examined by Western blot analysis. ODC activity was assayed radiometrically measuring [(14)CO(2)]-liberation. A dominant-negative PPARgamma mutant was transfected in Caco-2 cells to suppress PPARgamma-mediated functions. Antiproliferative effects of resveratrol closely correlate with a dose-dependent increase of endogenous ceramides (p<0.001). Compared to controls the cell-permeable ceramide analogues C2- and C6-ceramide significantly inhibit ODC-activity (p<0.001) in colorectal cancer cells. C6-ceramide further diminished protein levels of protooncogenes c-myc (p<0.05) and ODC (p<0.01), which is strictly related to the ability of ceramides to inhibit cell growth in a time- and dose-dependent manner. These results were further confirmed using inhibitors of sphingolipid metabolism, where only co-incubation with a serine palmitoyltransferase (SPT) inhibitor could significantly counteract resveratrol-mediated actions. These data suggest that the induction of ceramide de novo biosynthesis but not hydrolysis of sphingomyelin is involved in resveratrol-mediated inhibition of ODC. In contrast to the regulation of catabolic spermidine/spermine acetyltransferase by resveratrol, inhibitory effects on ODC occur PPARgamma-independently, indicating independent pathways of resveratrol-action. Due to our findings resveratrol could show great chemopreventive and therapeutic potential in the treatment of colorectal cancers.

Colorectal cancer protective effects and the dietary micronutrients folate, methionine, vitamins B6, B12, C, E, selenium, and lycopene

The data reported here were obtained from the case-control arm of a large, comprehensive, population-based investigation of colorectal cancer incidence, etiology, and survival, the Melbourne Colorectal Cancer Study, conducted in Melbourne, Australia. This part of the case-control study was designed to identify dietary factors associated with colorectal cancer risk in 715 incident cases compared with 727 age/sex frequency-matched randomly chosen community controls, in which a quantitative assessment of all foods eaten was made. New data are presented on the potential of two groups of micronutrients as protective agents, namely, those involved in DNA methylation, synthesis, and repair (folate, methionine, and vitamins B6 and B12) and those with antioxidant properties (selenium, vitamins E and C, and lycopene). The adjusted odds ratios showed that for folate there was significant protection for rectal cancer in second and third quintiles of consumption but not for colon cancer, and this was similar for methionine consumption. Vitamin B6 consumption was significantly protective for both colon and rectal cancer at the higher quintiles, and this was similar for vitamin B12. Dietary selenium was significantly protective at middle quintiles of consumption at both cancer sites. Dietary vitamins E and C were statistically significantly protective for both colon and rectal cancer at all levels of consumption, and for both vitamins there was a dose-response effect of increasing protection, particularly so for colon cancer. Lycopene was not associated with colorectal cancer risk. A combined model included vitamins E, C, and B12 and selenium as micronutrients protective for colorectal cancer and folate, which, however, showed an increased risk at the highest level of consumption. These data support the proposition that a diet containing the dietary micronutrients involved in DNA methylation (folate, methionine, and vitamins B6 and B12) and some of those with antioxidant properties (selenium and vitamins E and C) may have a role to play in lowering colorectal cancer risk and also that such protection can be achieved by dietary means alone.

Dietary intake of calcium, fiber and other micronutrients in relation to colorectal cancer risk: Results from the Shanghai Women's Health Study

We evaluated the associations of dietary intake of calcium, fiber and vitamins with colorectal cancer risk in a population-based prospective cohort study conducted among Chinese women in Shanghai. Subjects were recruited in urban Shanghai from March 1997 to May 2000. All subjects were interviewed in-person to obtain information on demographic and lifestyle factors and anthropometric measurement was conducted. Usual dietary intake, using a validated food frequency questionnaire was assessed at the baseline survey. After following a total of 73,314 women for a median of 5.74 years, 283 incident colorectal cancer cases were recorded. Excluding the first 2 years of follow-up, a high intake of calcium was associated with a decreased risk of colorectal cancer. Comparing the highest quintile of nutrients intake to the lowest, the adjusted relative risk for colorectal cancer was 0.6 (p value for trend = 0.023) for calcium. No apparent associations were found for fiber, total vitamin A, carotene, vitamins B1, B2, B3, C and E with colorectal cancer risk. Our results suggest that calcium may be protective against colorectal cancer development even at a lower consumption level compared to Western populations.

Aged garlic extract has chemopreventative effects on 1,2-dimethylhydrazine-induced colon tumors in rats

Garlic has been reported to have chemopreventive effects against a variety of cancers. However, different garlic preparations contain different constituents. We investigated the chemopreventive effect of aged garlic extract (AGE), an odorless product from prolonged extraction of fresh garlic, on colon carcinogenesis and cell proliferation in 1,2-dimethylhydrazine (DMH)-induced colon neoplastic rats. Rats were given weekly subcutaneous injections of DMH (20 mg/kg) for 20 wk, and fed either a basal diet or one containing 4% AGE. Serum from AGE-treated rats contained detectable S-allylcysteine. The AGE diet significantly reduced the number of colon tumors and aberrant crypt foci compared to the basal diet. Cell proliferation of normal-appearing colonic mucosa was assessed by MIB-5 immunohistochemistry. AGE treatment significantly decreased the mean MIB-5-labeling index. These findings suggest AGE has a chemopreventive effect on colon carcinogenesis through suppression of cell proliferation.

Prospects in NSAID-derived chemoprevention of colorectal cancer

There is strong evidence for an important role for increased COX (cyclo-oxygenase)-2 expression and PG (prostaglandin) E2 production in colorectal tumorigenesis. PGE(2) acts through four E-prostanoid receptors (EP1-4). COX-2 has therefore become a target for the potential chemoprevention and therapy of colorectal cancer. However, any therapeutic/preventive strategy has the potential to have an impact on physiological processes and hence result in side effects. General COX (COX-1 and -2) inhibition by traditional NSAIDs (non-steroidal anti-inflammatory drugs), such as aspirin, although chemopreventive, has some side effects, as do some conventional COX-2-selective NSAIDs. As PGE2 is thought to be the major PG species responsible for promoting colorectal tumorigenesis, research is being directed to a number of protein targets downstream of COX-2 that might allow the selective inhibition of the tumour-promoting activities of PGE2, while minimizing the associated adverse events. The PGE synthases and E-prostanoid receptors (EP1-4) have therefore recently attracted considerable interest as potential novel targets for the prevention/therapy of colorectal cancer. Selective (and possibly combinatorial) inhibition of the synthesis and signalling of those PGs most highly associated with colorectal tumorigenesis may have some advantages over COX-2-selective inhibitors.

Molecular mechanisms of econazole-induced toxicity on human colon cancer cells: G0/G1 cell cycle arrest and caspase 8-independent apoptotic signaling pathways

Econazole (Eco), a potent broad-spectrum anti-fungal agent, has been used in the treatment of superficial mycosis. Eco is a store-operated Ca2+ channel antagonist which induces cytotoxic cell death of leukemia. However, little is known about its cytotoxic effect upon solid tumor cells. The purpose of this study is to investigate both the in vitro and in vivo molecular mechanisms of Eco-induced toxicity on colon cancer cells. We used COLO 205 cell line and nude mice xenograft model to investigate the cytotoxic effect of Eco. We demonstrated that lower doses Eco (5-20 microM) arrested human colon cancer cells at the G0/G1 phase of the cell cycle. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated while CDK2 and CDK4 kinase activity were significantly suppressed by Eco treatment in COLO 205 cells. At higher doses (40-60 microM), Eco induced COLO 205 cells apoptosis evidenced by ladder formation in DNA fragmentation assay and sub-G1 peak in flow cytometry analysis. Western blot analysis showed that caspases 3, 9 but not 8 were activated by high dose Eco treatment to the COLO 205 cells accompanied with cytochrome c and apoptosis-inducing factor (AIF) translocation. Significant anti-tumorigenesis effect was further demonstrated in vivo by treating nude mice bearing COLO 205 tumor xenografts with Eco 50 mg/kg intraperitoneally. Our findings highlight the molecular mechanisms underlying the Eco-induced toxicity on colon cancer cells.

5-ASA and colorectal cancer chemoprevention in inflammatory bowel disease: can we afford to wait for 'best evidence'?

Patients with inflammatory bowel disease have a higher risk of developing colorectal cancer. The main risk factors for colorectal cancer are not suitable targets for therapeutic intervention, and primary chemoprevention is an intriguing therapeutic option. The analogies between acetyl-salicylic acid and 5-amino-salicylic acid, and the results obtained by using acetyl-salicylic acid as a chemopreventive agent in patients with sporadic colorectal cancer have prompted the study of potential chemopreventive effects of 5-amino-salicylic acid in inflammatory bowel disease. The results of both epidemiological and experimental studies have shown that long-term 5-amino-salicylic acid treatments appear to have a chemopreventive effect. The evidence for this effect is provided by retrospective and case-control studies whose results, however, do not reach the highest grades for evidence-based recommendations. Nevertheless, these results are supported by a series of experimental studies demonstrating the multiplicity of actions of 5-amino-salicylic acid. Although data regarding the chemopreventive effect of 5-amino-salicylic acid may not be rigorous enough to meet the criteria for the highest evidence-based medicine recommendations, we feel that the argument to wait until we have Grade A evidence is not necessarily rational in this case, because discontinuation of 5-amino-salicylic acid treatment to perform a randomised controlled trial would be unethical secondary to their proven efficacy for maintenance treatment.

Molecular mechanisms of the chemopreventive effects of resveratrol and its analogs in carcinogenesis

Resveratrol (3,4',5-trihydroxy-trans-stilbene), a phytoalexin found in grape skins, peanuts, and red wine, has been reported to exhibit a wide range of biological and pharmacological properties. It has been speculated that dietary resveratrol could be an explanation for the so-called 'French paradox' as it may act as an antioxidant, promote nitric oxide production, inhibit platelet aggregation, and increase high-density lipoprotein cholesterol, and thereby serve as a cardioprotective agent. Recently, it has been demonstrated that resveratrol can function as a cancer chemopreventive agent, and there has been a great deal of experimental effort directed toward defining this effect. It has been shown that resveratrol and some of its analogs interfere with signal transduction pathways, modulate cell cycle-regulating proteins, and is a potent inducer of apoptosis in multiple carcinoma cell lines. This review summarizes the recent advances that have provided new insights into the molecular mechanisms underlying the promising properties of resveratrol.

Mesalazine (5-aminosalicylic acid) micropellets show similar efficacy and tolerability to mesalazine tablets in patients with ulcerative colitis--results from a randomized-controlled trial

BACKGROUND

Formulations containing 5-aminosalicylic acid, such as mesalazine, are the gold standard of treatment for mild-to-moderate ulcerative colitis. Current oral regimens require the use of large tablets and frequent dosing to reach the recommended treatment dose. Mesalazine micropellets were designed to allow less frequent dosing in an easier to swallow formulation.

AIM

To compare the efficacy of mesalazine micropellets with the tablet formulation in patients with mild-to-moderate ulcerative colitis.

METHODS

This phase 2, double-blind, active-controlled, parallel-group, multiple dose clinical trial randomized 362 patients to either mesalazine micropellets or tablets, at a dosage of 3 g/day. The primary efficacy end-point was the incidence of clinical remission within 8 weeks, defined as the sum of clinical activity index components 1-4 (CAI(C1-4)) < or = 2.

RESULTS

CAI(C1-4) decreased significantly in both treatment groups within 8 weeks. The micropellet formulation showed confirmatory non-inferiority with statistical significance compared with the tablet formulation, with regard to the incidence of clinical remission (odds ratio in according-to-protocol population 1.008; 95% CI: 0.623-1.632). There was no significant difference in the incidence of adverse events.

CONCLUSIONS

The mesalazine micropellet formulation is as effective as tablets in patients with mild-to-moderate ulcerative colitis, enabling a larger dose to be taken comfortably and conveniently, thereby potentially improving patient compliance, treatment response and quality of life.