Recent advances in colorectal cancer genetics and diagnostics

Survival prediction and prognostic factors in colorectal cancer after curative surgery: insights from cox regression and neural networks

Medical research frequently relies on Cox regression to analyze the survival distribution of cancer patients. Nonetheless, in specific scenarios, neural networks hold the potential to serve as a robust alternative. In this study, we aim to scrutinize the effectiveness of Cox regression and neural network models in assessing the survival outcomes of patients who have undergone treatment for colorectal cancer. We conducted a retrospective study on 284 colorectal cancer patients who underwent surgery at Imam Khomeini clinic in Hamadan between 2001 and 2017. The data was used to train both Cox regression and neural network models, and their predictive accuracy was compared using diagnostic measures such as sensitivity, specificity, positive predictive value, accuracy, negative predictive value, and area under the receiver operating characteristic curve. The analyses were performed using STATA 17 and R4.0.4 software. The study revealed that the best neural network model had a sensitivity of 74.5% (95% CI 61.0-85.0), specificity of 83.3% (65.3-94.4), positive predictive value of 89.1% (76.4-96.4), negative predictive value of 64.1% (47.2-78.8), AUC of 0.79 (0.70-0.88), and accuracy of 0.776 for death prediction. For recurrence, the best neural network model had a sensitivity of 88.1% (74.4-96.0%), specificity of 83.7% (69.3-93.2%), positive predictive value of 84.1% (69.9-93.4%), negative predictive value of 87.8% (73.8-95.9%), AUC of 0.86 (0.78-0.93), and accuracy of 0.859. The Cox model had comparable results, with a sensitivity of 73.6% (64.8-81.2) and 85.5% (78.3-91.0), specificity of 89.6% (83.8-93.8) and 98.0% (94.4-99.6), positive predictive value of 84.0% (75.6-90.4) and 97.4% (92.6-99.5), negative predictive value of 82.0% (75.6-90.4) and 88.8% (0.83-93.1), AUC of 0.82 (0.77-0.86) and 0.92 (0.89-0.95), and accuracy of 0.88 and 0.92 for death and recurrence prediction, respectively. In conclusion, the study found that both Cox regression and neural network models are effective in predicting early recurrence and death in patients with colorectal cancer after curative surgery. The neural network model showed slightly better sensitivity and negative predictive value for death, while the Cox model had better specificity and positive predictive value for recurrence. Overall, both models demonstrated high accuracy and AUC, indicating their usefulness in predicting these outcomes.

MEG8：An Indispensable Long Non-coding RNA in Multiple Cancers

BACKGROUND

As a member of long non-coding RNAs (lncRNAs), maternally expressed gene 8 (MEG8) has been found involving in the progression of a variety of cancers and playing a regulatory role. Therefore, MEG8 may turn into a new therapeutic target for cancer in the future. The purpose of this review is to illustrate the molecular mechanism and physiological function of MEG8 in various cancers.

METHODS

We retrieved and analyzed related articles about MEG8, lncRNAs and cancers, and then summarize the pathophysiological mechanisms of MEG8 in cancer development.

RESULTS

LncRNA MEG8 participates in various cancers progression, thus influencing the proliferation, migration, and invasion of cancers. However, the expression of MEG8 is abnormally upregulated in non-small cell lung cancer (NSCLC), pancreatic cancer (PC), liver cancer (HCC), pituitary adenoma (PA) and hemangioma (HA), and inhibited in colorectal cancer (CRC), ovarian cancer (OC) and giant cell tumor (GCT), suggesting its clinical value in cancer therapy.

CONCLUSIONS

LncRNA MEG8 is expected to be a new therapeutic target or biomarker for a wide range of cancers in the future.

Genome-wide expression profiling in colorectal cancer focusing on lncRNAs in the adenoma-carcinoma transition

Background

Long non-coding RNAs (lncRNAs) play a fundamental role in colorectal cancer (CRC) development, however, lncRNA expression profiles in CRC and its precancerous stages remain to be explored. We aimed to study whole genomic lncRNA expression patterns in colorectal adenoma–carcinoma transition and to analyze the underlying functional interactions of aberrantly expressed lncRNAs.

Methods

LncRNA expression levels of colonic biopsy samples (20 CRCs, 20 adenomas (Ad), 20 healthy controls (N)) were analyzed with Human Transcriptome Array (HTA) 2.0. Expression of a subset of candidates was verified by qRT-PCR and in situ hybridization (ISH) analyses. Furthermore, in silico validation was performed on an independent HTA 2.0, on HGU133Plus 2.0 array data and on the TCGA COAD dataset. MiRNA targets of lncRNAs were predicted with miRCODE and lncBase v2 algorithms and miRNA expression was analyzed on miRNA3.0 Array data. MiRNA-mRNA target prediction was performed using miRWALK and c-Met protein levels were analyzed by immunohistochemistry. Comprehensive lncRNA-mRNA-miRNA co-expression pattern analysis was also performed.

Results

Based on our HTA results, a subset of literature-based CRC-associated lncRNAs showed remarkable expression changes already in precancerous colonic lesions. In both Ad vs. normal and CRC vs. normal comparisons 16 lncRNAs, including downregulated LINC02023, MEG8, AC092834.1, and upregulated CCAT1, CASC19 were identified showing differential expression during early carcinogenesis that persisted until CRC formation (FDR-adjusted p < 0.05). The intersection of CRC vs. N and CRC vs. Ad comparisons defines lncRNAs characteristic of malignancy in colonic tumors, where significant downregulation of LINC01752 and overexpression of UCA1 and PCAT1 were found. Two candidates with the greatest increase in expression in the adenoma-carcinoma transition were further confirmed by qRT-PCR (UCA1, CCAT1) and by ISH (UCA1). In line with aberrant expression of certain lncRNAs in tumors, the expression of miRNA and mRNA targets showed systematic alterations. For example, UCA1 upregulation in CRC samples occurred in parallel with hsa-miR-1 downregulation, accompanied by c-Met target mRNA overexpression (p < 0.05).

Conclusion

The defined lncRNA sets may have a regulatory role in the colorectal adenoma-carcinoma transition. A subset of CRC-associated lncRNAs showed significantly differential expression in precancerous samples, raising the possibility of developing adenoma-specific markers for early detection of colonic lesions.

Assessment of beta-catenin expression by immunohistochemistry in colorectal neoplasms and its role as an additional prognostic marker in colorectal adenocarcinoma

BACKGROUND

Cancer is one of the world's biggest health care challenges, with colorectal cancer (CRC) being one of the three most frequently encountered malignancy worldwide. The main cause of mortality associated with CRC is tumour invasion and metastasis. Pathogenesis of CRC is a multistep process, during which different molecular pathways come into play. The cardinal genomic alteration that has been found universally present in CRC is a mutation in the adenomatous polyposis coli gene (APC). APC mutation causes unrestricted action of the Wnt signaling pathway which subsequently enhances the intracellular accumulation of a protein called beta-catenin, responsible for cell proliferation, differentiation and enhanced survival of colorectal epithelial cells.

AIM

This study was conducted to analyze beta-catenin expression in various colorectal neoplasms, and its change with respect to different grades and stage of colorectal adenocarcinoma.

STUDY DESIGN

This was a cross-sectional observational study.

METHODS

A total of 66 cases were enrolled in this study. Census method of sampling was used. Data was collected using a pre-designed, pretested semi-structured schedule on dependent variables like beta-catenin expression and independent variables like clinico-pathological profile including dietary history, macroscopic findings, histological type, histological grade, stage and other relevant parameters.An institution based cross sectional observational study was performed between February 2016 and July 2017. Representative sections taken from the specimens included in the study were subjected to histopathological examination followed by immunohistochemistry [IHC] for beta-catenin expression; the data obtained were analyzed by mean ± SD, Student t test, Chi-square/ Fisher Exact test using statistical software SPSS 18.0.

RESULTS

A statistically significant correlation (P = 0.004), of beta-catenin localization and IHC score was noted between the benign, premalignant and malignant neoplasms following a gradual transition from a membranous to a nuclear positivity; also, a significant (P<0.001) correlation between beta-catenin nuclear score and the corresponding American Joint Committee on Cancer (AJCC) stage of colorectal adenocarcinoma was also found in this study.

CONCLUSION

The purpose of this study was to determine the change in beta-catenin expression which demonstrates a gradual shift from a membranous to subsequent cytoplasmic and nuclear positivity from normal colorectal tissue to benign, premalignant and malignant neoplasms respectively. This property of beta-catenin can determine the malignant potential of various premalignant neoplasms of the large intestine, thus aiding in an early initiation of prophylactic treatment, which can prevent the development of an invasive disease. The membranous, cytoplasmic and nuclear scores show a linear progression with the advancing stages of colorectal carcinoma, making beta-catenin a prognostic marker in malignant colorectal neoplasms.

Metformin inhibits β-catenin phosphorylation on Ser-552 through an AMPK/PI3K/Akt pathway in colorectal cancer cells

Several epidemiologic studies have revealed strong inverse associations between metformin use and risk of colorectal cancer development. Nevertheless, the underlying mechanisms are still uncertain. The Wnt/β-catenin pathway, which plays a central role in intestinal homeostasis and sporadic colorectal cancer development, is regulated by phosphorylation cascades that are dependent and independent of Wnt. Here we report that a non-canonical Ser⁵⁵² phosphorylation in β-catenin, which promotes its nuclear accumulation and transcriptional activity, is blocked by metformin via AMPK-mediated PI3K/Akt signaling inhibition.

The association between the TP53 Arg72Pro polymorphism and colorectal cancer: An updated meta-analysis based on 32 studies

Several previous studies evaluated the association between the Arg72Pro (rs1042522) polymorphism in the TP53 tumor suppressor gene and colorectal cancer (CRC). However, the results are conflicting. This meta-analysis aimed to shed new light on the precise association between TP53 variants and CRC. We analyzed 32 published case-control studies involving 8,586 cases and 10,275 controls using crude odd ratios (ORs) with 95% confidence intervals (CIs). The meta-analysis was performed using a fixed-effect or random-effects model, as appropriate. We found that the TP53 Arg72Pro polymorphism was not significantly associated with CRC risk in the overall population. However, subgroup analysis based on ethnicity revealed an increased risk of CRC among Asians (CC vs. GC+GG: OR=1.22, 95% CI: 1.02-1.45), and similar results were found for rectal cancer (CC vs. GC+GG: OR=1.34, 95% CI: 1.120-1.62). These results suggest that the TP53 Arg72Pro polymorphism CC genotype may contribute to an increased risk of CRC, especially for rectal cancer and among Asians.

Carcinoma-associated fibroblasts affect sensitivity to oxaliplatin and 5FU in colorectal cancer cells

The importance of tumor microenvironment (TME) as a relevant contributor to cancer progression and its role in the development of de novo resistance to targeted therapies has become increasingly apparent. However, the mechanisms of microenvironment-mediated drug resistance for nonspecific conventional chemotherapeutic agents, such as platinum compounds or antimetabolites, are still unclear.

Here we describe a mechanism induced by soluble factors released by carcinoma-associated fibroblasts (CAFs) that induce the translocation of AKT, Survivin and P38 to the nucleus of tumor cells. These changes are guided to ensure DNA repair and the correct entrance and exit from mitosis in the presence of chemotherapy. We used conditioned media (CM) from normal-colonic fibroblasts and paired CAFs to assess dose response curves of oxaliplatin and 5-fluorouracil, separately or combined, compared with standard culture medium. We also evaluated a colony-forming assay and cell death to demonstrate the protective role of CAF-CM. Immunofluorescence confirmed the translocation of AKT, P38 and Survivin to the nucleus induced by CAF-soluble factors. We also have shown that STAT3 or P38 inhibition provides a promising strategy for overcoming microenvironment-mediated resistance. Conversely, pharmacologic AKT inhibition induces an antagonistic effect that relieves a cMET and STAT3-mediated compensatory feedback that might explain the failure of AKT inhibitors in the clinic so far.

Genome-wide association study identified copy number variants associated with sporadic colorectal cancer risk

Background

Multiple single nucleotide polymorphisms (SNPs) have been associated with colorectal cancer (CRC) risk. The role of structural or copy number variants (CNV) in CRC, however, remained unclear. We investigated the role of CNVs in patients with sporadic CRC.

Methods

A genome-wide association study (GWAS) was performed on 1000 Singapore Chinese patients aged 50 years or more with no family history of CRC and 1000 ethnicity-matched, age-matched and gender-matched healthy controls using the Affymetrix SNP 6 platform. After 16 principal component corrections, univariate and multivariate segmentations followed by association testing were performed on 1830 samples that passed quality assurance tests.

Results

A rare CNV region (CNVR) at chromosome 14q11 (OR=1.92 (95% CI 1.59 to 2.32), p=2.7e-12) encompassing CHD8, and common CNVR at chromosomes 3q13.12 (OR=1.54 (95% CI 1.33 to 1.77), p=2.9e-9) and 12p12.3 (OR=1.69 (95% CI 1.41 to 2.01), p=2.8e-9) encompassing CD47 and RERG/ARHGDIB, respectively, were significantly associated with CRC risk. CNV loci were validated in an independent replication panel using an optimised copy number assay. Whole-genome expression data in matched tumours of a subset of cases demonstrated that copy number loss at CHD8 was significantly associated with dysregulation of several genes that perturb the Wnt, TP53 and inflammatory pathways.

Conclusions

A rare CNVR at 14q11 encompassing the chromatin modifier CHD8 was significantly associated with sporadic CRC risk. Copy number loss at CHD8 altered expressions of genes implicated in colorectal tumourigenesis.

The screening of the functional microRNA binding site SNPs in sporadic colorectal cancer genes

Sporadic colorectal cancer (sCRC) is one of the most commonly diagnosed cancers worldwide, but few genetic markers have been identified and used for its early detection. MicroRNAs are diverse cellular regulators in cancer pathogenesis that bind to the 3'-untranslated region (3'-UTR) of their target mRNAs, and variants within the miRNA target sites on sCRC-related genes may influence its pathogenesis. To investigate this possibility, we used a bioinformatical method to screen SNPs for putative changes in miRNA recognition sites within the 3'-UTR of sCRC-related genes. The rs11466537 single nucleotide polymorphism was predicted to modify the regulation of hsa-miR-1193 on the Transforming Growth Factor β Receptor II (TGFBR2) gene. Additionally, luciferase reporter assays indicated that hsa-miR-1193 bound the T allele more strongly than the A allele of rs11466537 (with A being the less frequent variant), and real time-polymerase chain reaction and western blot analysis showed that TGFBR2 is significantly repressed by hsa-miR-1193. Furthermore, overexpression of hsa-miR-1193 promoted HT-29 cell proliferation, while the loss of hsa-miR-1193 inhibited the process. Finally, the rs11466537 genotyping result revealed that the frequency of A allele carriers was 1.5% in the control blood samples, but 0 in the sCRC patients' normal colon tissue samples. Our results demonstrated that hsa-miR-1193 may be involved in sCRC tumourigenesis at least in part by suppression of TGFBR2, and the A allele of rs11466537 disturbed the regulation of hsa-miR-1193 on TGFBR2.

Effects of dual modified resistant indica rice starch on azoxymethane-induced incipient colon cancer in mice

In this study, the effects of different doses of dual modification-treated (DMT) indica rice resistant starch (IR-RS) on azoxymethane (AOM)-induced early colon cancer in mice were investigated. The investigated factors included body weight, gastrointestinal emptying rate, the number and morphology of aberrant crypt foci (ACFs) and the specific expressions of adenomatous polyposis coli (APC), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and cytochrome c genes. The results demonstrated that DMT IR-RS controlled the increase in the body weights of the mice, increased the gastrointestinal emptying rates and reduced the numbers of ACFs and aberrant crypts. Reverse transcription-polymerase chain reaction revealed that DMT IR-RS promoted the expression of APC, Bax and cytochrome c and inhibited the expression of Bcl-2. These results demonstrate that a DMT IR-RS diet may induce apoptosis and has beneficial health effects in AOM-induced early colon cancer in mice.

Investigating The Frequency of Serrated Polyps/Adenomas and Their Subtypes in Colonic Polyp Samples

BACKGROUND

The purpose of this study was to determine the frequency of Serrated polyps of colonic polyps samples in Hazrat_e Rasoul_e Akram Hospital over ten years.

MATERIALS

The target group in this study was patients with colonic polyps in Hazrat_e Rasoul_e Akram Hospital. Pathologic evaluation of these patients was done. Serrated polyps, by location, gender, age and type of polyps were divided and frequency of them were determined separately.

RESULTS

Of 381 patients studied, 224 (58.79%) and 157(41.20%) were males and females, respectively. Mean age of patients was 59.25 years. In initial diagnosis, frequency of Adenomatous polyp, Hyperplastic polyp and Mixed polyp were 92.44% and 5.33%, and 2.22%, respectively. In final diagnosis (Second evaluation), frequency of Adenomatous polyp, Hyperplastic polyp, Mixed polyp, Sessile Serrated Adenoma/ Polyp, Traditional Serrated Adenoma and SPU (Serrated Polyp Unclassifiable) were 90.44%, 4.88%, 2.44%, 1.11%, 0.66% and 0.44%, respectively. 72.13% and 27.86% of polyps were low grade dysplasia and high grade dysplasia, respectively. According to the results of this study, the incidence of all types of polyps detected was more in men than women. Rectum and sigmoid were most abundant in the area polyp in both initial and final diagnosis.

CONCLUSION

Despite the low prevalence of Serrated polyps in patients, early diagnosis is the best action to reduce morbidity and mortality. Probability of the risk of progression from low grade to high grade dysplasia and transforming into Adenocarcinoma is high in Serrated polyps.

FEATURES

Fighting Cancer with Immunotherapy.

21st Century Cancer Warfare: A Glimpse into the Operations of a Modern Radiotherapy Unit.

Is Colorectal Carcinomas due to ‘Bad Luck’ or Is It Preventable?

Asian Point of View on Cancer.

Improving Overall Survival in Hepatocellular Carcinoma through a Multi-Disciplinary Approach: Intra-Tumoral Heterogeneity, Immunology and the Promise of Better Outcomes.

Cancer of the Cervix – Can It be Prevented?

MiR-622 inhibited colorectal cancer occurrence and metastasis by suppressing K-Ras

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide, with many oncogenes and anti-oncogenes involved. MicroRNAs (miRNAs) are a class of small, noncoding RNA molecules that can adjust downstream targets. Accumulating evidence has revealed that microRNAs govern the occurrence and development of cancer. Here, we studied the role of miR-622 in CRC and clarified the underlying mechanism. We detected that miR-622 was down-regulated in colorectal tumor tissues and cell lines and that miR-622 was lower in metastatic CRC tissues compared with that in non-metastatic specimens. Furthermore, we confirmed that miR-622 inhibited tumor proliferation and migration in vitro. Through dual-luciferase reporter assay, we found kirsten rat sarcoma (K-Ras) gene was the direct target of miR-622. More importantly, K-Ras overexpression can rescue the inhibitory effect of miR-622 on CRC development. All these data were validated in colon xenograft tumor model. MiR-622-K-Ras signal pathway was a potentially new direction in the development of screening target and therapeutic treatments for CRC. © 2015 Wiley Periodicals, Inc.

Contemporary proteomic strategies for clinical epigenetic research and potential impact for the clinic

Novel proteomic methods are revealing the intricacy of the epigenetic landscape affecting gene regulation and improving our knowledge of the pathogenesis of complex diseases. Despite the enormous amount of data regarding epigenetic modifications present in DNA and histones, deciphering their biological relevance in the context of the disease and health is currently still an ongoing process. Here, we consider the relationship between epigenetic research in tumorigenesis and the prospect of knowledge transfer to clinical use, focusing primarily on the epigenetic histone post-translational modifications, which could be used as biomarkers. We additionally focus on the use of proteomic techniques in research and evaluate their usefulness in clinical setting.

Attitudes and knowledge of medical practitioners to hereditary cancer clinics and cancer genetic testing

Genetic testing for susceptibility for common cancers is widely available. Thus, doctors have a role in identifying and referring patients who would benefit from a consultation with a specialist in genetics. This study aims to assess doctors' referral rates, knowledge and attitudes towards cancer genetic testing, broken down by specialty (gastrointestinal, breast/ovarian, other specialties and General Practitioners-GPs). A 4-page questionnaire was mailed out to the GPs of all patients seen in 2012 in the Hereditary Cancer Clinic of St. Vincent's Hospital Sydney (n = 128) and all the specialists in St. Vincent's Hospital Sydney that might refer to the HCC (n = 33). 50 questionnaires were returned (31 %). Most doctors had referred a patient for cancer genetic testing (90 %). The average proportion of patients referred was 1 in 68.5 patients with breast/ovarian specialists referring the most, followed by gastrointestinal specialists and GPs. There was suboptimal knowledge of cancer genetic testing amongst doctors. Breast/ovarian specialists were most knowledgeable, followed by gastrointestinal specialists, other specialists and GPs. There were indications of inappropriate referral amongst doctors. Most (77.6 %) doctors were willing to receive further information on cancer genetics. Nearly all (94 %) doctors believe that it is their duty to inform an individual at high risk for hereditary cancer that cancer genetic counselling and testing is available. The majority of doctors have positive attitudes towards cancer genetic testing. Defective knowledge scores, however, indicate that doctors need further training or tools to enable them to refer patients appropriately for cancer genetic testing.

Genetic predisposition to colorectal cancer: Where we stand and future perspectives

The development of colorectal cancer (CRC) can be influenced by genetic factors in both familial cases and sporadic cases. Familial CRC has been associated with genetic changes in high-, moderate- and low-penetrance susceptibility genes. However, despite the availability of current gene-identification techniques, the genetic causes of a considerable proportion of hereditary cases remain unknown. Genome-wide association studies of CRC have identified a number of common low-penetrance alleles associated with a slightly increased or decreased risk of CRC. The accumulation of low-risk variants may partly explain the familial risk of CRC, and some of these variants may modify the risk of cancer in patients with mutations in high-penetrance genes. Understanding the predisposition to develop CRC will require investigators to address the following challenges: the identification of genes that cause uncharacterized hereditary cases of CRC such as familial CRC type X and serrated polyposis; the classification of variants of unknown significance in known CRC-predisposing genes; and the identification of additional cancer risk modifiers that can be used to perform risk assessments for individual mutation carriers. We performed a comprehensive review of the genetically characterized and uncharacterized hereditary CRC syndromes and of low- and moderate-penetrance loci and variants identified through genome-wide association studies and candidate-gene approaches. Current challenges and future perspectives in the field of CRC predisposition are also discussed.

Early diagnosis of colorectal cancer in rats with DMH induced carcinogenesis by means of urine autofluorescence analysis

Cancer is one of the most highlighted topics of current research. Early detection of this disease allows more effective therapy, hence higher chance of cure. Application of fluorescence spectral techniques into oncological diagnostic is one of the potential alternatives. Chemically induced carcinogenesis in rats is widely used model for exploration of various aspects of colorectal cancer. This study shows value of discriminate analysis of urine fluorescent fingerprint between healthy control group of rats and those with dimethylhydrazine induced early lesions of colorectal cancer. Using fluorescence spectroscopy, significant difference (P < 0.05) between both of group was achieved.

Lack of association between interleukin-8-251 T>A polymorphism and colorectal cancer risk: a meta-analysis based on 3,019 cases and 3,984 controls

PURPOSE

The results of recent published studies focusing on IL-8 polymorphism in colorectal cancer susceptibility have often been inconsistent. We therefore carried out a meta-analysis based on independent studies to assess the association.

METHODS

Nine case-control studies with 7,003 individuals (3,019 cases and 3,984 controls) were included in this meta-analysis through searching the databases of PubMed, Excerpta Medica Database (EMBASE), and Chinese Biomedical Literature Database (CBM; Chinese) (up to Aug 1st, 2012). The odds ratio (OR) and 95% confidence interval (95%CI) were used to assess the strength of the association. Meta-analysis was conducted in a fixed/random effect model.

RESULTS

No obvious associations were found for all genetic models when all studies were pooled into the meta-analysis (for A vs. T: OR = 1.084, 95% CI = 0.971- 1.209, P = 0.019; for TA vs. TT: OR = 1.18, 95% CI = 0.943-1.475, P = 0.001; for AA vs. TT: OR = 1.155, 95% CI = 0.916-1.456, P = 0.014; for AA+TA vs. TT: OR = 1.170, 95% CI =0.953-1.437, P = 0.001; for AA vs. TT+TA: OR = 1.044, 95% CI = 0.886-1.230, P = 0.097). In the subgroup analyses by ethnicity (Caucasian) and source of controls (population based), also no significant associations were found for all genetic models.

CONCLUSIONS

Result suggests that the IL-8-251T>A polymorphism is not associated with colorectal cancer risk. Because of the limitations of this meta-analysis, this finding demands further investigation.

Single-nucleotide polymorphism associations for colorectal cancer in southern chinese population

OBJECTIVE

Genome-wide association studies (GWAS) have identified 11 loci that influence the risk of developing colorectal cancer (CRC). Given that these studies were conducted in European Caucasian populations, it is not clear whether the results are relevant for populations with different ethnicities. The aim of this study was to examine these associations in a southern Chinese population.

METHODS

Eleven single-nucleotide polymorphisms (SNPs), rs12701937, rs16892766, rs7014346, rs6983267, rs719725, rs10795668, rs3802842, rs4444235, rs9929218, rs10411210, and rs961253, were genotyped in 229 CRC patients and 267 controls using the MassArray SNP genotyping system.

RESULTS

Evidence of an association with CRC was found for four of the 11 loci. The strongest associations were with rs4444235 and rs961253, with significant odds ratios close to those reported in previous GWAS. Among these four loci, rs719725 and rs4444235 were significantly associated with female gender, rs3802842, rs961253, and rs4444235 with early disease onset, and rs3802842 with later disease onset. However, no associations with CRC risk were detected for six other loci (rs9929218, rs10411210, rs12701937, rs7014346, rs6983267, and rs10795668), and one SNP, rs16892766, was not polymorphic in any of the study participants.

CONCLUSION

The rs4444235 and rs961253 loci are strongly associated with the risk of CRC in southern Chinese.

Gene expression variations: potentialities of master regulator polymorphisms in colorectal cancer risk

Colorectal cancer (CRC) is one of the most common cancers worldwide with a peak of incidence in industrialised countries. It is a complex disease related to environmental and genetic risk factors. Low-penetrance genetic variations contribute significantly to sporadic and familial form of CRC. Genome-wide association studies (GWAS) have uncovered numerous robust associations between common variants and CRC risk; only a few of those were protein altering non-synonymous polymorphisms. One of the hypotheses is that non-coding and intergenic variants may change the expression levels of one or several target genes and, thus, account for a fraction of phenotypic differences, including susceptibility to CRC. Such genetic variations have been detected as expression quantitative loci (eQTLs) that show linkage/association to a large number of genes and have been defined as "master regulators of transcription". In the present work, we overview the potentialities to use results from GWAS and eQTL studies in the identification as well as investigation of master regulators in CRC susceptibility.

CHEK2 1100delC, IVS2+1G>A and I157T mutations are not present in colorectal cancer cases from Turkish population

BACKGROUND

The cell cycle checkpoint kinase 2 (CHEK2) protein participates in the DNA damage response in many cell types. Germline mutations in CHEK2 (1100delC, IVS2+1G>A and I157T) have been impaired serine/threonine kinase activity and associated with a range of cancer types. This hospital-based case-control study aimed to investigate whether CHEK2 1100delC, IVS2+1G>A and I157T mutations play an important role in the development of colorectal cancer (CRC) in Turkish population.

METHODS

A total of 210 CRC cases and 446 cancer-free controls were genotyped for CHEK2 mutations by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele specific-polymerase chain reaction (AS-PCR) methods.

RESULTS

We did not find the CHEK2 1100delC, IVS2+1G>A and I157T mutations in any of the Turkish subjects.

CONCLUSION

Our result demonstrate for the first time that CHEK2 1100delC, IVS2+1G>A and I157T mutations have not been agenetic susceptibility factor for CRC in the Turkish population. Overall, our data suggest that genotyping of CHEK2 mutations in clinical settings in the Turkish population should not be recommended. However, independent studies are need to validate our findings in a larger series, as well as in patients of different ethnic origins.

Association of single nucleotide polymorphisms in IL-12 and IL-27 genes with colorectal cancer risk

OBJECTIVES

Interleukin-12 (IL-12) plays an important role in antitumor immunity. Interleukin-27 (IL-27) is a novel IL-12 family member. The present studies demonstrate that IL-27 mediates potent antitumor activity. However, No studies have examined the association of these polymorphism with colorectal cancer (CRC). Therefore, we investigated the relationship of IL-12 and IL-27 gene polymorphisms and CRC.

DESIGN AND METHODS

We analyzed polymorphisms of IL-12 gene 16974 A/C and IL-27 gene -964 A/G, 2905 T/G, 4730 T/C in 410 patients with CRC and 450 controls, using PCR-RFLP method.

RESULTS

There were no significant differences in the genotype and allele frequencies of IL-12 and IL-27 gene polymorphisms between the group of patients with CRC and the controls. Furthermore, no association was found between IL-12 family gene polymorphisms and different clinical stages in patients with CRC.

CONCLUSION

These findings suggest that IL-12 and IL-27 gene polymorphisms may not be involved in susceptibility to CRC.

NFκB1 and NFκBIA polymorphisms are associated with increased risk for sporadic colorectal cancer in a southern Chinese population

BACKGROUND

Nuclear factor κB (NFκB) plays a key role in the regulation of apoptosis. The function of NFκB is inhibited by binding to NFκB inhibitor (IκB), and disruption of the balance of NFκB and IκB is related to the development of many diseases, including tumors. Therefore, we hypothesized that the NFκB1 (-94del/insATTG) and NFκBIA (2758 A>G) polymorphisms were associated with colorectal cancer (CRC) susceptibility.

METHODS

In a hospital-based case-control study of 1001 CRC patients and 1005 cancer-free controls frequency matched by age and sex, we genotyped polymorphisms using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and performed luciferase assays and Western blotting analysis to identify whether genetic variants in NFκBIA alter its gene expressions and functions and thus cancer risk.

RESULTS

We found that both NFκB1-94 ins/delATTG and NFκBIA 2758 A>G polymorphisms were correlated with CRC risk (OR = 1.47; 95%CI = 1.14-1.86, and OR = 1.38; 95% CI = 1.14-1.66, respectively). Furthermore, when evaluated these two polymorphisms together, the combined genotypes with 2 variant (risk) alleles (2758GG and -94ins/ins+del/ins) were associated with an increased risk of CRC (OR = 1.71; 95% CI = 1.23-2.38) compared to 0 variant, and the significant trend for 2 variant (risk) alleles were more pronounced among subgroups of aged <60 years, women, never drinkers, never smokers, persons with a normal BMI and those with a family history of cancer(P(trend)<0.01). Moreover, luciferase assays showed that the G allele in the 3'UTR significantly decreased NFκBIA mRNA stability and the A allele regulation by miRNA449a in vitro and that the NFκBIA protein expression levels of the AA+AG variant carriers were significantly higher in peritumoral tissues than those of the 2758GG genotype.

CONCLUSION

NFκB1 and NFκBIA polymorphisms appear to jointly contribute to risk of CRC. These two variants may be a genetic modifier for CRC susceptibility in this southern Chinese population.

TGF-β/TGF-β receptor system and its role in physiological and pathological conditions

The TGF-β (transforming growth factor-β) system signals via protein kinase receptors and Smad mediators to regulate a plethora of biological processes, including morphogenesis, embryonic development, adult stem cell differentiation, immune regulation, wound healing and inflammation. In addition, alterations of specific components of the TGF-β signalling pathway may contribute to a broad range of pathologies such as cancer, cardiovascular pathology, fibrosis and congenital diseases. The knowledge about the mechanisms involved in TGF-β signal transduction has allowed a better understanding of the disease pathogenicity as well as the identification of several molecular targets with great potential in therapeutic interventions.

Prevalence of MYH-associated polyposis related to three recurrent mutations in Morocco

BACKGROUND

MYH-associated polyposis (MAP) is an autosomal recessive inherited disease. People with MAP tend to develop multiple adenomatous colon polyps during their lifetime and have an increased risk of colorectal cancer. MAP has only recently been described and there is much to be learned about the condition. Recessively inherited mutations in the base excision repair gene MYH have recently been associated with predisposition to colorectal adenomas and cancer. The epidemiology of MYH-associated polyposis (MAP) is poorly known in populations with high levels of consanguinity like North African populations, in particular in Morocco, and the MAP carrier frequency in the general Moroccan population has never been evaluated. The present study was carried out among the Moroccan population, using molecular epidemiology methods, to estimate the prevalence of homozygote or compound heterozygote genotype conferring MAP due to three mutations reported as recurrent in MAP: c.494A>G (Y165C), c.1145G>A (G382D) and c.1186_1187insGG (p.Glu396fsX42).

METHODS

To estimate the prevalence of MYH mutations in Morocco, DNA extracted from blood samples of 400 healthy Moroccans was tested for recurrent MYH mutations using real-time PCR or DNA fragment analysis. Heterozygotes profiles were confirmed by direct sequencing. We searched for the mutations c.494A>G and c.1145G>A in 400 subjects, and the mutation c.1186_1187insGG in 250 subjects.

RESULTS

One subject was heterozygous for c.494A>G (1/400 or 0.25%), three others for c.1145G>A (3/400 or 0.75%) and one was heterozygous for p.Glu396fsX42 (1/250 or 0.4%). The carrier frequency of one of these three mutations in the Moroccan population was calculated to be 1.4% and the frequency of homozygous or compound heterozygote for these three recurrent mutations is 1/10 000.These figures allowed one to estimate at 3500 the number of Moroccans with high risk of developing colon cancer due only to these three recurrent mutations.

CONCLUSION

This preliminary study shows that the Moroccan population is at risk for MAP. This could help to define diagnosis strategies and patient care and may also have implications for genetic counselling.

Resveratrol decreases the levels of miR-155 by upregulating miR-663, a microRNA targeting JunB and JunD

An inflammatory component is present in the microenvironment of most neoplastic tissues, including those not causally related to an obvious inflammatory process. Several microRNAs, and especially miR-155, play an essential role in both the innate and adaptative immune response. Resveratrol (trans-3,4',5-trihydroxystilbene) is a natural antioxidant with anti-inflammatory properties that is currently at the stage of preclinical studies for human cancer prevention. Here, we establish that, in human THP-1 monocytic cells as well as in human blood monocytes, resveratrol upregulates miR-663, a microRNA potentially targeting multiple genes implicated in the immune response. In THP-1 cells, miR-663 decreases endogenous activator protein-1 (AP-1) activity and impairs its upregulation by lipopolysaccharides (LPS), at least in part by directly targeting JunB and JunD transcripts. We further establish that the downregulation of AP-1 activity by resveratrol is miR-663 dependent and that the effects of resveratrol on both AP-1 activity and JunB levels are dose dependent. Finally, we show that resveratrol impairs the upregulation of miR-155 by LPS in a miR-663-dependent manner. Given the role of miR-155 in the innate immune response and the fact that it is upregulated in many cancers, our results suggest that manipulating miR-663 levels may help to optimize the use of resveratrol as both an anti-inflammatory and anticancer agent against malignancies associated with high levels of miR-155.

Genome-wide association study for colorectal cancer identifies risk polymorphisms in German familial cases and implicates MAPK signalling pathways in disease susceptibility

Genetic susceptibility accounts for approximately 35% of all colorectal cancer (CRC). Ten common low-risk variants contributing to CRC risk have been identified through genome-wide association studies (GWASs). In our GWAS, 610 664 genotyped single-nucleotide polymorphisms (SNPs) passed the quality control filtering in 371 German familial CRC patients and 1263 controls, and replication studies were conducted in four additional case-control sets (4915 cases and 5607 controls). Known risk loci at 8q24.21 and 11q23 were confirmed, and a previously unreported association, rs12701937, located between the genes GLI3 (GLI family zinc finger 3) and INHBA (inhibin, beta A) [P = 1.1 x 10(-3), odds ratio (OR) 1.14, 95% confidence interval (CI) 1.05-1.23, dominant model in the combined cohort], was identified. The association was stronger in familial cases compared with unselected cases (P = 2.0 x 10(-4), OR 1.36, 95% CI 1.16-1.60, dominant model). Two other unreported SNPs, rs6038071, 40 kb upstream of CSNK2A1 (casein kinase 2, alpha 1 polypeptide) and an intronic marker in MYO3A (myosin IIIA), rs11014993, associated with CRC only in the familial CRC cases (P = 2.5 x 10(-3), recessive model, and P = 2.7 x 10(-4), dominant model). Three software tools successfully pointed to the overrepresentation of genes related to the mitogen-activated protein kinase (MAPK) signalling pathways among the 1340 most strongly associated markers from the GWAS (allelic P value < 10(-3)). The risk of CRC increased significantly with an increasing number of risk alleles in seven genes involved in MAPK signalling events (P(trend) = 2.2 x 10(-16), OR(per allele) = 1.34, 95% CI 1.11-1.61).

Genome-wide scan identifies a copy number variable region at 3q26 that regulates PPM1L in APC mutation-negative familial colorectal cancer patients

Familial adenomatous polyposis (FAP) is an autosomal dominantly inherited form of colorectal cancer (CRC) caused by mutation in the adenomatous polyposis coli (APC) gene. However, APC mutations are not detected in 10-50% of FAP patients. We searched for a new cancer gene by performing genome-wide genotyping on members of an APC mutation-negative FAP variant family and ethnicity-matched healthy controls. No common copy number change was found in all affected members using the unaffected members and healthy controls as baseline. A 111 kb copy number variable (CNV) region at 3q26.1 was shown to have copy number loss in all eight polyps compared to matched lymphocytes of two affected members. A common region of loss in all polyps, which are precursors to CRC, is likely to harbor disease-causing gene in accordance to Knudsen's "two-hit" hypothesis. There is, however, no gene within the deleted region. A 2-Mb scan of the genomic region encompassing the deleted region identified PPM1L, coding for a novel serine-threonine phosphatase in the TGF-beta and BMP signaling pathways. Real-time PCR analyses indicate that the 3'UTR of PPM1L transcript was down-regulated more than two-folds in all six polyps and tumors compared to matched mucosa of the affected member. This down-regulation was not observed in APC mutation-positive FAP patients. Our results suggest that the CNV region at 3q26 harbors an element that regulates the expression of an upstream candidate tumor suppressor, PPM1L, thus providing a novel mechanism for colorectal tumorigenesis in APC mutation-negative familial CRC patients.

Differential effects of NOD2 polymorphisms on colorectal cancer risk: a meta-analysis

INTRODUCTION

Since Kurzawski et al. described an association between the 3020insC NOD2 single nucleotide polymorphism and the risk of colorectal cancer(CRC) in 2004, reports published in the past several years have controversial results regarding the relationship between the development of CRC and NOD2 gene polymorphisms. To clarify the potential role of NOD2 P286S, R702W, G908R, and 3020insC polymorphisms in CRC patients, we have undertaken a systematic review and meta-analysis of published articles.

MATERIALS AND METHODS

Studies reporting on NOD2 polymorphisms and CRC were searched in the PubMed, EMBASE, and the Science Citation Index from the inception of each database to May, 2009. The search strategy included the keywords "CRC", "colon cancer", "rectal cancer", "polymorphism", and "NOD2/CARD15".

RESULT

Eight eligible case-control studies about Caucasians from four countries contributed data on 5,888 subjects (cases: 3,524; controls: 2,364). Compared to the wild genotype, the R702W, G908R, and 3020insC polymorphisms were associated with an increased risk of CRC (odds ratio (OR): 1.59, 1.98, 1.44; 95% confidence interval (CI): 1.09-2.32, 1.14-3.44, 1.13-1.84; P = 0.02, 0.01, 0.003). However, P268S polymorphism did not influence CRC risk (OR: 1.27; CI: 0.32-5.00; P = 0.73).

CONCLUSIONS

These findings indicate that NOD2 R702W, G908R, and 3020insC polymorphisms contribute to CRC susceptibility in Caucasians. Meta-analysis of these polymorphisms in NOD2 gene will help determine their role in CRC carcinogenesis.

Wnt modulators in the biotech pipeline

The purpose of this review is to provide a better understanding for the LRP co-receptor-mediated Wnt pathway signaling. Using proteomics, we have also subdivided the LRP receptor family into six sub-families, encompassing the twelve family members. This review includes a discussion of proteins containing a cystine-knot protein motif (i.e., Sclerostin, Dan, Sostdc1, Vwf, Norrin, Pdgf, Mucin) and discusses how this motif plays a role in mediating Wnt signaling through interactions with LRP.

Germline bone morphogenesis protein receptor 1A mutation causes colorectal tumorigenesis in hereditary mixed polyposis syndrome

OBJECTIVES

Hereditary mixed polyposis syndrome (HMPS) is characterized by polyps of mixed adenomatous/hyperplastic/atypical juvenile histology that are autosomal dominantly inherited and that eventually lead to colorectal cancer (CRC). Although CRC with adenomatous polyps is initiated by inactivating adenomatous polyposis coli (APC), the initiating event of CRC with mixed polyps remains unclear. We aimed to identify the underlying germline defect in HMPS.

METHODS

We screened for bone morphogenesis protein receptor 1A (BMPR1A) mutation by exonic sequencing, reverse-transcriptase polymerase chain reaction (PCR) followed by cDNA sequencing, and multiplex ligation-dependent probe amplification (MLPA) analysis in eight Singapore Chinese HMPS families.

RESULTS

Germline BMPR1A defects were found in four (50%) families. In two families, it is shown to co-segregate with the disease phenotype in all affected members over three generations, indicating that it is the disease-causing mutation. CRC incidence is 75%. The most defining characteristic is the presence of mixed hyperplastic-adenomatous polyps. Juvenile polyps are rarely reported, and if present, are usually of mixed components. Detailed histology of the polyps from one patient over 11 years distinguishes HMPS from juvenile polyposis syndrome (JPS). We report further the first cases of Wilms' tumor and papillary thyroid carcinoma associated with BMPR1A germline defect.

CONCLUSIONS

Germline BMPR1A defect is the disease-causing mutation in 50% of the HMPS families. If patients present with mixed morphology polyps in the large bowel that are autosomal dominantly inherited and corresponding absence of upper gastrointestinal abnormalities, the gene to begin mutation screening should be BMPR1A rather than APC.