Recent advances in understanding of interactions between genes and diet in the etiology of colorectal cancer

Hypermethylated WNT10A and its clinical significance in colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease in which unique subtypes are characterized by distinct genetic and epigenetic alterations. DNA methylation, a well-documented epigenetic modification, is a promising biomarker for the diagnosis and prognosis of cancers, including CRC. WNT10A is a member of the Wnt family. It belongs to the Wnt signaling pathway and is involved in CRC. However, studies regarding the methylation and expression of WNT10A in CRC are limited. In the current study, we analyzed the methylation status of WNT10A in 146 patients with CRC and normal controls. These samples were classified into two groups. The first group was an initial discovery set (i.e., fresh tissue samples from 40 patients with CRC and adjacent normal control samples). The second group was an independent validation set (i.e., formalin-fixed and paraffin-embeded [FFPE] samples from 106 patients with CRC and cutting edge tissues). The results showed a higher level of WNT10A hypermethylation of in CRC samples than in controls (Fresh tissue cohort: P = 2.8E-5; FFPE cohort: P = 3.6E-4).This finding was verified by WNT10A methylation data from The Cancer Genome Atlas portal (TCGA) (P = 1.9E-83). Subgroup analysis of clinical characteristics showed a higher WNT10A methylation level in elder patients (aged > 60 y) (P = 0.037) and, patients with distant metastasis (P = 0.033), rectal cancer (P = 0.03), and mucinous adenocarcinoma (P = 0.02). Furthermore, TCGA RNAseq data demonstrated lower WNT10A expression in patients with CRC than in controls (P = 4.0E-3) and showed a negative correlation between expression and methylation (r = -0.37, P = 5.7E-13). Moreover, the efficiency of WNT10A methylation for CRC diagnosis was analyzed in both cohorts of the present study and the TCGA cohorts, which indicated the potential use of WNT10A methylation as a tool for diagnosis of CRC.

Expression of FOXP1 and Colorectal Cancer Prognosis

BACKGROUND

Forkhead box gene P1 (FOXP1) has proven to be a valuable prognostic biomarker in lymphomas, but little is known about this gene in colorectal cancer (CRC).

OBJECTIVES

To investigate the expression of FOXP1 in CRC and its potential associations with outcome in CRC.

METHODS

We studied the expression pattern of FOXP1 retrospectively via immunohistochemistry in a series of 165 - CRC cases. Fluorescent in situ hybridization and RNA sequencing on FOXP1 knockdown cell lines were performed to investigate the mechanism of action and target genes of FOXP1.

RESULTS

Complete loss of nuclear FOXP1 expression was observed in 11.5% of the subjects. A total of 70.9% of subjects showed a heterogeneous FOXP1 expression pattern, and 17.6% of them had high FOXP1 expression. Impaired expression of FOXP1 was significantly correlated with reduced survival rates by multivariate analysis (P = .004). We found no chromosomal aberrations involving FOXP1 in individuals with FOXP1 negativity via immunohistochemical testing. RNA sequencing revealed that genes involved in inflammation and cell proliferation were differentially expressed after FOXP1 knockdown.

CONCLUSIONS

In our case series, loss of FOXP1 was associated with reduced survival rates in CRC tissue. Also, FOXP1 affects proliferation and inflammatory reaction in colorectal neoplasia.

Colonoscopic Polypectomies and Recommendations on the Colonoscopy Follow-up Intervals Depending on Endoscopic and Histopathological Findings

The Aim:

To show histopathological diagnoses after colonoscopic polypectomy in the University Hospital Center (KBC) Split with recommendations on further follow-up colonoscopy depending on the endoscopic and histological findings.

Patients and Methods:

The study included 2842 patients who underwent colonoscopy in a two-year period (2008-2009), followed by a detailed analysis of 350 patients in which one or more polyps were simultaneously removed and 163 patients who were only sampled for histological analysis. Patients from the National Program for Colorectal Cancer Prevention and patients in which colonoscopy is indicated as part of daily outpatient or inpatient treatment were included as well.

Results:

During 2008 and 2009 in KBC Split, out of a total of 2842 colonoscopies, 350 patients underwent colonoscopic polypectomy, whereby 618 polyps were removed (1-8 polyps in individual patients), while in 163 patients only biopsy specimens were sampled. Out of the total of 557 polyps sent for histological analysis, 236 were hyperplastic (42%), 193 were identified as tubular adenoma (35%), 84 were tubulovillous (15%), 18 villous (3%), 9 were adenocarcinoma (2%) and other 17 (3%). In 35 (15.4%) polyps high-grade dysplasia was found. The largest number of nonpolypectomized changes confirmed the presence of adenocarcinoma (76-47%), adenomas and hyperplastic polyps were 37 (22%) and regular findings 23 (14%). Mucosal high-grade dysplasia was demonstrated in 35 (23.1%) biopsied changes.

Conclusion:

Colonoscopies with polypectomy decreased the risk of the formation of colorectal cancer in these patients almost to the level of risk in patients who have not even had a polyp during colonoscopy. Arguably the best method of prevention and early detection of colorectal cancer are already widely established national programs. The next qualitative level is constantly improving the quality of colonoscopy with clear criteria and the establishment of a body to evaluate the performers and the equipment, and making recommendations on the colonoscopy follow-up intervals depending on endoscopic and histopathological findings of patients who for any reason underwent colonoscopy.

Chemoprevention of colon and small intestinal tumorigenesis in APC(min/+) mice by SHetA2 (NSC721689) without toxicity

The occurrence of intestinal polyps in people at high risk for developing colorectal cancer provides an opportunity to test the efficacy of chemoprevention agents. In this situation of treating otherwise healthy people, the potential for toxicity must be minimal. The small-molecule flexible heteroarotinoid (Flex-Het), called SHetA2, has chemoprevention activity in organotypic cultures in vitro and lack of toxicity at doses capable of inhibiting xenograft tumor growth in vivo. The objective of this study was to evaluate SHetA2 chemoprevention activity and toxicity in the APC(min/+) murine model. Oral administration of SHetA2 at 30 and 60 mg/kg five days per week for 12 weeks significantly reduced development of intestinal polyps by 40% to 60% depending on the dose and sex of the treatment group. Immunohistochemical and Western blot analysis of polyps showed reduced levels of cyclin D1 and proliferating cell nuclear antigen in both SHetA2 treatment groups. Western blot analysis also showed SHetA2 induction of E-cadherin, Bax, and caspase-3 cleavage along with reduction in Bcl-2, COX-2, and VEGF, consistent with SHetA2 regulation of apoptosis, inflammation, and angiogenesis. Neither dose caused weight loss nor gross toxicity in APC(min/+) or wild-type littermates. Magnetic resonance imaging (MRI) of cardiac function showed no evidence of SHetA2 toxicity. SHetA2 did not alter left ventricular wall thickness. In summary, SHetA2 exerts chemoprevention activity without overt or cardiac toxicity in the APC(min/+) model. SHetA2 modulation of biomarkers in colon polyps identifies potential pharmacodynamic endpoints for SHetA2 clinical trials.

EGF +61A>G polymorphism and gastrointestinal cancer risk: a HuGE review and meta-analysis

Emerging evidences from preclinical and clinical studies have shown that epidermal growth factor (EGF) has some effectiveness against endogenously arising carcinogenesis. Functional +61A>G polymorphism (rs4444903 A>G) in the promoter region of the EGF gene was observed to modulate EGF levels, thus affecting the susceptibility to gastrointestinal cancer; but individually published studies showed inconclusive results. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to derive a more precise estimation of the association between EGF +61A>G polymorphism and gastrointestinal cancer risk. A literature search of Pubmed, Embase, Web of Science and Chinese BioMedical databases from inception through July 2012 was conducted. Twelve studies were assessed with a total of 2868 gastrointestinal cancer cases and 4278 healthy controls. When all the eligible studies were pooled into the meta-analysis, the results showed that the G allele and GG genotype of EGF +61A>G polymorphism might increase the risk of gastrointestinal cancer. In the stratified analysis by cancer types, the G allele and GG genotype of EGF +61A>G polymorphism showed displayed significant correlations with increased risk of esophageal cancer. We also found significant correlations between the G carrier (GG+AG) and GG genotype of EGF +61A>G polymorphism and colorectal cancer risk. However, EGF +61A>G polymorphism did not appear to have an influence on gastric cancer susceptibility. Results from the current meta-analysis indicate that EGF +61A>G polymorphism might increase the risk of esophageal and colorectal cancers. Nevertheless, further studies are needed to determine whether genetic associations between EGF +61A>G polymorphism and susceptibility to gastric cancer are significant.

Contribution of behavioral risk factors and obesity to socioeconomic differences in colorectal cancer incidence

BACKGROUND

Health behaviors are known risk factors for colorectal cancer and are more common in low socioeconomic status (SES) populations. We evaluated the extent to which behavioral risk factors and body mass index (BMI) explain SES disparities in colorectal cancer incidence, overall and by tumor location.

METHODS

We analyzed prospective National Institutes of Health-AARP Diet and Health Study data on 506 488 participants who were recruited in 1995-1996 from six US states and two metropolitan areas and followed through 2006. Detailed baseline data on risk factors for colorectal cancer, including health behaviors, were obtained using questionnaires. SES was measured by self-reported education and census-tract data. The outcome was primary incident invasive colorectal adenocarcinoma. Poisson regression was used to estimate the association between SES and risk of incident colorectal cancer, with adjustment for age, sex, race and ethnicity, family history, and state of residence. The model estimates were used to derive percentage mediation by behavioral risk factors; bias-corrected 95% confidence intervals were obtained through bootstrap techniques.

RESULTS

Seven-thousand six-hundred seventy-six participants developed colorectal cancer during follow-up. SES differences in prevalence of physical inactivity, unhealthy diet, smoking, and unhealthy weight each explained between 11.3% (BMI) and 21.6% (diet) of the association between education and risk of colorectal cancer and between 8.6% (smoking) and 15.3% (diet) of the association between neighborhood SES and risk of colorectal cancer. Health behaviors and BMI combined explained approximately 43.9% (95% CI = 35.1% to 57.9%) of the association of education and 36.2% (95% CI = 28.0% to 51.2%) of the association of neighborhood SES with risk of colorectal cancer. The percentage explained by all factors and BMI combined was largest for right colon cancers and smallest for rectal cancers.

CONCLUSION

A substantial proportion of the socioeconomic disparity in risk of new-onset colorectal cancer, and particularly of right colon cancers, may be attributable to the higher prevalence of adverse health behaviors in low-SES populations.

Inhibition or enhancement by 4 Pacific Island food plants against cancers induced by 2 amino-3-methylimidazo[4,5-f]quinoline in male Fischer 344 rats

A 1-yr carcinogenicity bioassay was conducted in rats fed 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), simultaneously with AIN-76/ high-fat (HF) diet alone, or with 10% starch replaced with kumara, pineapple, coconut, or taro, prepared as for a human diet. All of the non-IQ treated control, kumara, pineapple, or taro but not coconut-fed rats survived to 1 yr. None of the IQ-fed animals survived to 1 yr and although there were minor survival time differences among the groups, none was statistically significant. At sacrifice, IQ/HF controls had tumors in the skin, Zymbal's gland, ear canal, oral cavity, liver, and small intestine, totaling 32 among 20 animals. Kumara-fed rats had a similar tumor distribution but no tumors in the ear or oral cavity, and a total of 27 tumors among 20 animals, whereas pineapple-fed rats showed a somewhat lower tumor incidence (23/20 animals), including no small intestine lesions. Unexpectedly, a higher tumor incidence, especially of skin tumors, was seen in coconut and taro-fed animals (35/20 and 41/20 animals, respectively). In particular, the incidence of malignant liver tumors and gastrointestinal tumors were significantly increased in the taro-fed group in comparison with the kumara group.