Molecular biology of colorectal cancer

A new evaluation of the rearranged non-coding control region of JC virus in patients with colorectal cancer

BACKGROUND

Several studies have reported the presence of JC virus (JCV) in human tumors, The association of JCV and CRC remains controversial. This study aimed to evaluate the rearranged NCCR region of the detected JCV DNA in CRC patients' tissue samples.

METHODS

In this case-control study, tumor tissues (n = 60), adjacent normal tissues (n = 60), and urine samples (n = 60) of the CRC patients were collected. The nested PCR was employed to detect the VP1 and NCCR regions of the JCV genome. The positive JCV PCR products were sequenced and a phylogenetic tree was constructed to determine the JCV genotypes. After extracting RNA and preparing cDNA, the expression of JCV LTAg was examined in 60 tumor tissues and 60 adjacent normal tissues. The analysis of JCV LTAg expression was performed using GraphPad Prism software version 8.

RESULTS

The analysis reveals that JCV DNA was detected in 35/60 (58.3%) tumor tissues, while 36/60 (60.0%) of adjacent normal tissues (p = 0.85). JCV DNA was detected in 42/60 (70.0%) urine samples when compared to 35/60 (58.3%) tumor tissues of CRC patients and was not found significant (P = 0.25). The phylogenetic tree analysis showed the dominant JCV genotype 3, followed by genotype 2D was distributed in tumor tissue, normal tissue, and urine samples of the CRC patients. Analysis of randomly selected NCCR sequences from JCV regions in tumor tissue samples revealed the presence of rearranged NCCR blocks of different lengths.: 431 bp, 292 bp, 449 bp, and 356 bp. These rearranged NCCR blocks differ from the rearranged NCCR blocks described in PML-type Mad-1, Mad-4, Mad-7, and Mad-8 prototypes. The expression of JCV LTAg was significantly different in tumor tissue compared to normal tissue, with a p-value of less than 0.002.

CONCLUSION

A significant proportion of 35%> of the tumor tissue and urine samples of the CRC patients was found to be positive for JCV DNA (P = 0.25). The parallel analysis of tumor and urine samples for JCV DNA further supports the potential for non-invasive screening tools. This study provides new insights into Rearranged NCCR variant isolates from patients with CRC. The significant difference in JCV LTAg expression between tumor and normal tissue indicates a latent JCV status potentially leading to cancer development.

SALL4 in gastrointestinal tract cancers: upstream and downstream regulatory mechanisms

Effective therapeutic targets and early diagnosis are major challenges in the treatment of gastrointestinal tract (GIT) cancers. SALL4 is a well-known transcription factor that is involved in organogenesis during embryonic development. Previous studies have revealed that SALL4 regulates cell proliferation, survival, and migration and maintains stem cell function in mature cells. Additionally, SALL4 overexpression is associated with tumorigenesis. Despite its characterization as a biomarker in various cancers, the role of SALL4 in GIT cancers and the underlying mechanisms are unclear. We describe the functions of SALL4 in GIT cancers and discuss its upstream/downstream genes and pathways associated with each cancer. We also consider the possibility of targeting these genes or pathways as potential therapeutic options for GIT cancers.

Phenolic Phytochemicals for Prevention and Treatment of Colorectal Cancer: A Critical Evaluation of In Vivo Studies

Colorectal cancer (CRC) is the third most diagnosed and second leading cause of cancer-related death worldwide. Limitations with existing treatment regimens have demanded the search for better treatment options. Different phytochemicals with promising anti-CRC activities have been reported, with the molecular mechanism of actions still emerging. This review aims to summarize recent progress on the study of natural phenolic compounds in ameliorating CRC using in vivo models. This review followed the guidelines of the Preferred Reporting Items for Systematic Reporting and Meta-Analysis. Information on the relevant topic was gathered by searching the PubMed, Scopus, ScienceDirect, and Web of Science databases using keywords, such as "colorectal cancer" AND "phenolic compounds", "colorectal cancer" AND "polyphenol", "colorectal cancer" AND "phenolic acids", "colorectal cancer" AND "flavonoids", "colorectal cancer" AND "stilbene", and "colorectal cancer" AND "lignan" from the reputed peer-reviewed journals published over the last 20 years. Publications that incorporated in vivo experimental designs and produced statistically significant results were considered for this review. Many of these polyphenols demonstrate anti-CRC activities by inhibiting key cellular factors. This inhibition has been demonstrated by antiapoptotic effects, antiproliferative effects, or by upregulating factors responsible for cell cycle arrest or cell death in various in vivo CRC models. Numerous studies from independent laboratories have highlighted different plant phenolic compounds for their anti-CRC activities. While promising anti-CRC activity in many of these agents has created interest in this area, in-depth mechanistic and well-designed clinical studies are needed to support the therapeutic use of these compounds for the prevention and treatment of CRC.

Molecular and cellular pathways in colorectal cancer: apoptosis, autophagy and inflammation as key players

BACKGROUND

Colorectal carcinogenesis (CRC) is one of the most aggressive forms of cancer, particularly in developing countries. It accounts for the second and third-highest reason for cancer-induced lethality in women and men respectively. CRC involves genetic and epigenetic modifications in colonic epithelium, leading to colon adenocarcinoma. The current review highlights the pathogenic mechanisms and multifactorial etiology of CRC, influenced by apoptosis, inflammation, and autophagy pathways.

METHODS

We have carried out a selective literature review on mechanisms contributing to the pathogenesis of CRC.

RESULTS

Resistance to senescence and apoptosis of the mesenchymal cells, which play a key role in intestinal organogenesis, morphogenesis and homeostasis, appears important for sporadic CRC. Additionally, inflammation-associated tumorigenesis is a key incident in CRC, supported by immune disruptors, adaptive and innate immune traits, environmental factors, etc. involving oxidative stress, DNA damage and epigenetic modulations. The self-digesting mechanism, autophagy, also plays a twin role in CRC through the participation of LC3/LC3-II, Beclin-1, ATG5, other autophagy proteins, and Inflammatory Bowel Disease (IBD) susceptibility genes. It facilitates the promotion of effective surveillance pathways and stimulates the generation of malignant tumor cells. The autophagy and apoptotic pathways undergo synergistic or antagonistic interactions in CRC and bear a critical association with IBD that results from the pro-neoplastic effects of persistent intestinal inflammation. Conversely, pro-inflammatory factors stimulate tumor growth and angiogenesis and inhibit apoptosis, suppressing anti-tumor activities.

CONCLUSION

Hence, research attempts for the development of potential therapies for CRC are in progress, primarily based on combinatorial approaches targeting apoptosis, inflammation, and autophagy.

Identification of a Five-MiRNA Expression Assay to Aid Colorectal Cancer Diagnosis

Introduction: One-third of colorectal cancer (CRC) patients present with advanced disease, and establishing control remains a challenge. Identifying novel biomarkers to facilitate earlier diagnosis is imperative in enhancing oncological outcomes. We aimed to create miRNA oncogenic signature to aid CRC diagnosis. Methods: Tumour and tumour-associated normal (TAN) were extracted from 74 patients during surgery for CRC. RNA was isolated and target miRNAs were quantified using real-time reverse transcriptase polymerase chain reaction. Regression analyses were performed in order to identify miRNA targets capable of differentiating CRC from TAN and compared with two endogenous controls (miR-16 and miR-345) in each sample. Areas under the curve (AUCs) in Receiver Operating Characteristic (ROC) analyses were determined. Results: MiR-21 (β-coefficient:3.661, SE:1.720, p = 0.033), miR-31 (β-coefficient:2.783, SE:0.918, p = 0.002), and miR-150 (β-coefficient:−4.404, SE:0.526, p = 0.004) expression profiles differentiated CRC from TAN. In multivariable analyses, increased miR-31 (β-coefficient:2.431, SE:0.715, p < 0.001) and reduced miR-150 (β-coefficient:−4.620, SE:1.319, p < 0.001) independently differentiated CRC from TAN. The highest AUC generated for miR-21, miR-31, and miR-150 in an oncogenic expression assay was 83.0% (95%CI: 61.7–100.0, p < 0.001). In the circulation of 34 independent CRC patients and 5 controls, the mean expression of miR-21 (p = 0.001), miR-31 (p = 0.001), and miR-150 (p < 0.001) differentiated CRC from controls; however, the median expression of miR-21 (p = 0.476), miR-31 (p = 0.933), and miR-150 (p = 0.148) failed to differentiate these groups. Conclusion: This study identified a five-miRNA signature capable of distinguishing CRC from normal tissues with a high diagnostic test accuracy. Further experimentation with this signature is required to elucidate its diagnostic relevance in the circulation of CRC patients.

miR-590-5p: A double-edged sword in the oncogenesis process

Accumulating evidence suggests the critical role of miR-590-5p in various aspects of cellular homeostasis, including cancer. Furthermore, we and others have recently demonstrated that miRNA-590-5p acts as an oncogene in some cancers while it acts as a tumor-suppressor in others. However, the role of miR-590-5p in oncogenesis is more complex, like a double-edged sword. Thus, this systematic review introduces the concept, mechanism, and biological function of miR-590-5p to resolve this apparent paradox. We have also described the involvement of miR-590-5p in crucial cancer-hallmarks processes like proliferation, invasion, metastasis, and chemo radioresistance. Finally, we have presented the possible genes/pathways targets of miR-590-5p through bioinformatics analysis. This review may help in designing better biomarkers and therapeutic targets for cancers.

MicroRNA Profile of Human Small Intestinal Tumors Compared to Colorectal Tumors

Small intestinal tumors (adenoma and adenocarcinoma, SIT) are rare, and their microRNA (miRNA) expression profiles have not been established. Previously, we reported a relationship between miRNA expression profiles and the development, growth, morphology, and anticancer drug resistance of colorectal tumors. Here, we demonstrate that the miRNA expression profile of SIT is significantly different from those of tumors of the colon. We compared the onco-related miRNA expression profiles of SIT and colorectal tumors and found them to be different from each other. The expressions of miR-143 and miR-145 were frequently downregulated in SIT and colorectal tumors but not in sessile serrated adenoma/polyp tumors. The profiles of SIT and colorectal carcinomas of miR-7, miR-21, and miR-34a were considerably different. Upregulation of miR-31 expression was not found in any SIT cases. Our data suggested that miR-143 and miR-145 might act as anti-oncomirs common to adenocarcinoma of the small intestine, similar to those of colorectal adenoma and other cancers. However, the expression profiles of the other miRNAs of SIT were significantly different from those of colorectal tumors. These findings contribute useful insights into the tumor development and diagnosis of SIT.

Mismatch repair protein deficiency assessed by immunohistochemistry in sporadic colorectal carcinoma

Context

Globally, colorectal carcinoma (CRC) ranks the third most commonly diagnosed malignant disease, one of the leading causes of cancer deaths.

Aims

To study the spectrum of clinicopathological characteristics of sporadic colorectal carcinoma and to assess mismatch repair gene deficiency by the expression pattern of the proteins assessed by immunohistochemistry.

Setting and Design

Observational study conducted in a tertiary care hospital in West Bengal.

Materials and Methods

Fifty-two surgically resected specimens of CRC received from January 2018 to May 2019 were studied for clinical, morphological, MSI status.

Statistical Analysis Used

IBM SPSS 23.

Results

A total of 50% of the cases belonged to younger and 50% to the older population, with male predominance being 53.8%. The most common histologic type was adenocarcinoma (88.5%). The majority was found to be well-differentiated carcinoma (50%). The majority cases were of the T3 stage accounting to 38.5%. A total of 24 out of 52 cases (46.15%) had an absent expression of at least one mismatch repair (MMR) protein. A significant correlation was found between the young age group and microsatellite instability (MSI) with a P value of 0.001. A significant association was found between MSI and tumor differentiation with P value of 0.018. A significant association was found between MSH6 and histological type with P value of 0.012. A significant association was found between MSI and tumor stage with P value of 0.032.

Conclusions

This study shows a significantly higher number of sporadic colon cancers involving the young age group, and younger cases showed significant association with MSI. This alarming trend needs validation by studies involving larger populations and can be helpful prognostically as well as in formulating chemotherapeutic regimens.

A novel phytosterol isolated from Datura inoxia, RinoxiaB is a potential cure colon cancer agent by targeting BAX/Bcl2 pathway

Plant sterols have been widely used as chemotherapeutic agents for colorectal cancer for years together. In this study, a novel phytosterol was isolated and characterized from the leaf extract of a medicinal plant, Datura inoxia and was coined as RinoxiaB (RB). This phytosterol was observed to have antiproliferative activity against human colon adenocarcinoma cells, HCT 15. The cell viability assay revealed the IC₅₀ value of the RB as 4 µM. Moreover, RB treated cells showed prominent morphological changes dose dependently and progressively increased the number of dead cells. Additionally, results of the comet, flow cytometry, and cell cycle analysis revealed that the majority of cells were arrested in their S and G2/M phase by blocking the mitotic spindle formation. The western blot analysis (Bcl-2, BAX, Cytochrome C, Caspases 9 & 3) clearly indicated that RB has the ability to induce apoptosis by significantly upregulating (P < 0.05) Bcl-2 and causing mitochondrial damage leading to Cytochrome C release and activation of caspases, which subsequently results in downregulation of BAX expression in the cytosol. Furthermore, the expression of tumor suppressors (p53 and p21) and cell cycle regulatory proteins (Cyclins D1 & B1) suggested that RB inhibit cell proliferation. Thus, the present finding concludes that RB can offer possible apoptotic effects by targeting BAX/Bcl2 pathway in HCT 15 cells, thus alleviating colon cancer.

The detection of interval colorectal cancers following screening by fecal immunochemical test may predict worse outcomes and prompt ethical concerns: a 6-year population-based cohort study in a full district

The rates of colorectal cancer (CRC) interval surveyed in screen-detected patients using a fecal immunochemical test (FIT) are not negligible. The aim of this study was to assess the effect of interval cancer on outcomes compared with a population with cancer diagnosed after a positive test result. All patients between 50 and 71 years of age, who were residents of the Mantua district, affected by CRC and operated on from 2005 to 2010 were reviewed. Other than patient-related, disease-related, and treatment-related factors and tumor location, this population was differentiated as either participating or not to screening and then into populations developing interval cancer after a negative FIT result. Mortality was investigated by univariate analysis and by overall survival rates. The mean age of the 975 patients enrolled was 62 years (61.7% males). Most patients (n=575, 59%) were not screen detected, and 400 (41%) were screen detected. Fifty-six (5.7%) patients in the latter group, representing 14% of the participants, developed interval cancer after a negative FIT result. Their cancer was mostly localized in the right colon (41.1%) instead of the left colon and rectum (P=0.02). They also showed higher stages (P=0.001), a moderate degree of differentiation (P=0.001), and overall higher mortality rates than patients with cancer diagnosed after a positive test result (P=0.001). The effect of interval CRC after screening with FIT resulted in worse outcomes compared with the FIT-positive group. With such findings, patients who had negative results for FIT should be informed of the risk of developing cancer within the rounds of screening to independently gain educational skills in the area of health prevention.

Colorectal carcinogenesis: Insights into the cell death and signal transduction pathways: A review

Colorectal carcinogenesis (CRC) imposes a major health burden in developing countries. It is the third major cause of cancer deaths. Despite several treatment strategies, novel drugs are warranted to reduce the severity of this disease. Adenomatous polyps in the colon are the major culprits in CRC and found in 45% of cancers, especially in patients 60 years of age. Inflammatory polyps are currently gaining attention in CRC, and a growing body of evidence denotes the role of inflammation in CRC. Several experimental models are being employed to investigate CRC in animals, which include the APC^min/+ mouse model, Azoxymethane, Dimethyl hydrazine, and a combination of Dextran sodium sulphate and dimethyl hydrazine. During CRC progression, several signal transduction pathways are activated. Among the major signal transduction pathways are p53, Transforming growth factor beta, Wnt/β-catenin, Delta Notch, Hippo signalling, nuclear factor erythroid 2-related factor 2 and Kelch-like ECH-associated protein 1 pathways. These signalling pathways collaborate with cell death mechanisms, which include apoptosis, necroptosis and autophagy, to determine cell fate. Extensive research has been carried out in our laboratory to investigate these signal transduction and cell death mechanistic pathways in CRC. This review summarizes CRC pathogenesis and the related cell death and signal transduction pathways.

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.

New Approaches To the Understanding of the Molecular Basis of Oral Cancer

Cancers of the oral cavity, salivary glands, larynx, and pharynx, collectively referred to as squamous cell carcinomas of the head and neck (HNSCC), are the sixth most common cancer among men in the developed world. The prognosis of HNSCC patients is still poor, which reflects the fact that although the risk factors for HNSCC are well-recognized, very little is known about the molecular mechanisms responsible for this malignancy. This review describes some of the current efforts and technological advances that have focused on the creation of a complete information infrastructure for genes expressed during squamous cell carcinogenesis. These include: the recently described HNSCC-specific chromosomal alterations (cCAP); the Head and Neck Cancer Genome Anatomy Project (HN-CGAP), whose goal is the systematic identification and cataloguing of known and novel genes expressed during tumor development; and the use of laser-capture microdissection (LCM), which is pivotal for the comprehensive molecular characterization of normal, pre-cancerous, and malignant cells by means of DNA-array technology. The latter provides the means for the analysis of expression patterns of thousands of genes simultaneously. The use of LCM for proteomics and DNA analysis is also included in this review. These revolutionary approaches are likely to have an unprecedented impact on cancer biology, and provide exciting opportunities to unravel the still-unknown mechanisms involved in squamous cell carcinogenesis. They are also expected to provide a molecular blueprint for HNSCC, thus helping to identify suitable markers for the early detection of pre-neoplastic lesions, as well as novel targets for pharmacological intervention in this disease.

Association of APC I1307K and E1317Q polymorphisms with colorectal cancer among Egyptian subjects

Colorectal cancer is a multifactorial disease that involves both environmental and genetic factors. The gene encoding adenomatous polyposis coli (APC) has been reported to be associated with colorectal cancer (CRC) risk in several ethnic populations. The aim of this work is to assess the association of the APC I1307K and E1317Q polymorphisms with CRC risk among Egyptian subjects. This study included 120 unrelated CRC Egyptian patients who were compared to 100 healthy controls from the same locality. For all subjects, DNA was genotyped for APC I1307K and E1317Q polymorphisms using the PCR-ARMS technique. The frequency of APC I1307K carrier (TA+AA genotypes) was noted to be significantly higher among cases with CRC compared to controls (18.3 vs. 9.0 %, OR 2.58, 95 % CI 1.09-6.09, p = 0.03). Also the frequency of the APC I1307K A allele was significantly higher among cases compared to controls (10.4 vs. 4.5 %, OR 2.47; 95 % CI 1.12-5.42, p = 0.03). On the contrast, the frequencies of APC E1317Q GC genotype and C allele showed no significant difference among CRC patients compared to controls (3.3 vs. 2.0 %, OR 1.69; 95 % CI 0.30-9.42, p = 0.69 and 2.1 vs. 1.0 %, OR 2.11; 95 % CI 0.40-10.97, p = 0.46, respectively). Cases of the APC I1307K and E1317Q carriers (TA+AA and GC) showed no significant difference compared to those with I1307K and E1317Q non-carriers (TT and GG) regarding their clinical and laboratory markers. APC I1307K variant was associated with an increased risk of CRC among Egyptian subjects.

The Role of Stem Cell DNA Methylation in Colorectal Carcinogenesis

Stems cells of the colon crypt are the origin of colon mature cells. Colorectal cancer cells are also suggested to originate from crypt stem cells undergoing a series of epigenetic and genetic alterations. Aberrant methylation plays important roles in early carcinogenesis and lead to altered gene expression and regulation, resulting in accumulation of damages to cell function and ultimately, malignant transformation. Aberrances in hypermethylation and hypomethylation act in different mechanism through the regulation of various genes during CSC carcinogenesis, and both of them play crucial roles in stem cell differentiation towards cancer cells. A large majority of epigenetic and genetic abnormalities that work coordinately in colorectal carcinogenesis are related to cell growth and division, indicating that the intrinsic abnormalities of CRC lie in dysregulation of basic cellular processes. Detection of abnormal methylation can be used in cancer screening and early detection, while reversal of aberrant methylation using drugs may have potential in cancer therapy. This review will provide an overview on the roles of aberrant methylation and a summary of genes that are affected during CRC carcinogenesis.

miR-375 inhibits the invasion and metastasis of colorectal cancer via targeting SP1 and regulating EMT-associated genes

Accumulating evidence has shown that aberrantly expressed microRNAs (miRNAs) are associated with tumor development and progression. Our previous study found that microRNA-375 (miR-375) was downregulated in colorectal cancer (CRC), but little is known concerning the role of miR-375 and the related mechanism in CRC development. The proliferation, invasion and migration effects were investigated by Cell Counting Kit-8 (CCK-8), colony formation and Transwell assays with or without Matrigel. In addition, candidate target genes were screened and validated by luciferase reporter and western blot assays. In addition, western blot analysis was performed to explore the molecular mechanisms associated with epithelial‑mesenchymal transition (EMT). It was found that miR-375 inhibited proliferation, invasion and migration in DLD1 and HCT8 cells. In addition, miR-375 negatively regulated Sp1 transcription factor (SP1) protein by directly binding to the 3'-untranslated region (3'-UTR). Furthermore, it was found that miR-375 regulated matrix metalloproteinase 2 (MMP2) and EMT-associated genes, E-cadherin, vimentin, snail, N-cadherin and β-catenin. In conclusion, miR-375 inhibited the proliferation, invasion and migration by directly targeting SP1 and regulating MMP2 and EMT-associated genes.

Integrated genomic analysis of colorectal cancer progression reveals activation of EGFR through demethylation of the EREG promoter

Key molecular drivers that underlie transformation of colonic epithelium into colorectal adenocarcinoma (CRC) are well described. However, the mechanisms through which clinically targeted pathways are activated during CRC progression have yet to be elucidated. Here, we used an integrative genomics approach to examine CRC progression. We used laser capture microdissection to isolate colonic crypt cells, differentiated surface epithelium, adenomas, carcinomas and metastases, and used gene expression profiling to identify pathways that were differentially expressed between the different cell types. We identified a number of potentially important transcriptional changes in developmental and oncogenic pathways, and noted a marked upregulation of EREG in primary and metastatic cancer cells. We confirmed this pattern of gene expression by in situ hybridization and observed staining consistent with autocrine expression in the tumor cells. Upregulation of EREG during the adenoma-carcinoma transition was associated with demethylation of two key sites within its promoter, and this was accompanied by an increase in the levels of epidermal growth factor receptor (EGFR) phosphorylation, as assessed by reverse-phase protein analysis. In CRC cell lines, we demonstrated that EREG demethylation led to its transcriptional upregulation, higher levels of EGFR phosphorylation, and sensitization to EGFR inhibitors. Low levels of EREG methylation in patients who received cetuximab as part of a phase II study were associated with high expression of the ligand and a favorable response to therapy. Conversely, high levels of promoter methylation and low levels of EREG expression were observed in tumors that progressed after treatment. We also noted an inverse correlation between EREG methylation and expression levels in several other cancers, including those of the head and neck, lung and bladder. Therefore, we propose that upregulation of EREG expression through promoter demethylation might be an important means of activating the EGFR pathway during the genesis of CRC and potentially other cancers.

New hope on the horizon for patients with metastatic colorectal cancer

Colorectal cancer is the second leading cause of cancer death in the USA. It is estimated that approximately 132,700 patients are diagnosed with, and more than 49,700 are expected to die of colorectal cancer each year. For many years, 5-fluorouracil was the only treatment option for patients with metastatic colorectal cancer but, over the last decade, the introduction and the US FDA approval of irinotecan, oxaliplatin and several monoclonal antibodies that target the VEGF and EGF receptor have markedly changed the therapeutic landscape. Most recently, regorafenib, ramucirumab and the novel orally active TAS-102 have also become available, presenting even more therapeutic options. In this review, we focus on emerging systemic therapy options for the management of advanced/metastatic colorectal cancer, particularly in the second-line/salvage settings, highlighting existing scientific evidence for the activity of, as well as future perspectives on, these more novel treatments.

Polymorphisms of cell cycle regulator genes CCND1 G870A and TP53 C215G: Association with colorectal cancer susceptibility risk in a Malaysian population

Colorectal cancer (CRC) occurs as a more common sporadic form and a less common familial form. Our earlier analysis of germline mutations of mismatch repair genes confirmed only 32% of familial CRC cases as Lynch syndrome cases. It was hypothesized that the remaining familial aggregation may be 'polygenic' due to single nucleotide polymorphisms (SNPs) of low penetrance genes involved in cancer predisposition pathways, such as cell cycle regulation and apoptosis pathways. The current case-control study involving 104 CRC patients (52 sporadic and 52 familial) and 104 normal healthy controls investigated the contribution of the SNPs cyclin D1 (CCND1) G870A and tumor protein p53 (TP53) C215G in modulating familial and sporadic CRC susceptibility risk. DNA was extracted from peripheral blood and the polymorphisms were genotyped by employing a polymerase chain reaction-restriction fragment length polymorphism method. The association between these polymorphisms and CRC susceptibility risk was calculated using a binary logistic regression analysis and deriving odds ratios (ORs). The A/A variant genotype of CCND1 and G/G variant genotype of TP53 exhibited a significantly greater association with the risk of sporadic CRC [CCND1: OR, 3.471; 95% confidence interval (CI), 1.443-8.350; P=0.005. TP53: OR, 2.829; CI, 1.119-7.152; P=0.026] as well as familial CRC susceptibility (CCND1: OR, 3.086; CI, 1.270-7.497; P=0.019. TP53: OR, 3.048; CI, 1.147-8.097; P=0.030). The results suggest a potential role of the SNPs CCND1 G870A and TP53 C215G in the modulation of sporadic and familial CRC susceptibility risk.

Colorectal carcinoma in the first decade of life: a systematic review

PURPOSE

The aim of this study is to better understand the main aspects related to colorectal carcinoma diagnosed in the first 10 years of life, through a systematic review.

METHODS

We carried out a bibliographic search in PubMed and LILACS, focusing on identifying publications or case reports about colorectal carcinoma in the first 10 years of life. The bibliographical analysis was made in two steps. During the first phase, we excluded those articles whose titles or abstracts did not correspond with the objective settled. Publications without abstract were also included in this phase. During the second phase, we look at the articles and evaluated their content, selecting the cases with colorectal cancer under 10 years old.

RESULTS

From 3880 publications, 132 were selected in the first phase and 84 were evaluated in the second phase. Based on these conditions, 33 articles have cases presented which 4 articles were case reviews and 29 were case reports. Duplicated cases were excluded from the analysis. Fifty-nine cases were described in English and Latin literature. There is an apparent similar proportion between the sexes, and the mean age was 8.6 years old. The main localization was the rectum and sigmoid (45.8 %). Pathologic findings showed that 86.4 % were adenocarcinoma. These tumors are frequently advanced at diagnosis. The Kaplan-Meier 60-month overall survival was 15.3 %. Dukes classification represents a factor related to survival (p = 0.03).

CONCLUSIONS

In children, colorectal carcinoma presents distinctive characteristics, which determines poor survival.

miR-135b Promotes Cancer Progression by Targeting Transforming Growth Factor Beta Receptor II (TGFBR2) in Colorectal Cancer

The transforming growth factor beta (TGF-β) signaling pathway is a tumor-suppressor pathway that is commonly inactivated in colorectal cancer (CRC). The inactivation of TGFBR2 is the most common genetic event affecting the TGF-β signaling pathway. However, the mechanism by which cancer cells downregulate TGFBR2 is unclear. In this study, we found that the TGFBR2 protein levels were consistently upregulated in CRC tissues, whereas its mRNA levels varied in these tissues, suggesting that a post-transcriptional mechanism is involved in the regulation of TGFBR2. Because microRNAs (miRNAs) are powerful post-transcriptional regulators of gene expression, we performed bioinformatic analyses to search for miRNAs that potentially target TGFBR2. We identified the specific targeting site of miR-135b in the 3'-untranslated region (3'-UTR) of TGFBR2. We further identified an inverse correlation between the levels of miR-135b and TGFBR2 protein, but not mRNA, in CRC tissue samples. By overexpressing or silencing miR-135b in CRC cells, we experimentally validated that miR-135b directly binds to the 3'-UTR of the TGFBR2 transcript and regulates TGFBR2 expression. Furthermore, the biological consequences of the targeting of TGFBR2 by miR-135b were examined using in vitro cell proliferation and apoptosis assays. We demonstrated that miR-135b exerted a tumor-promoting effect by inducing the proliferation and inhibiting the apoptosis of CRC cells via the negative regulation of TGFBR2 expression. Taken together, our findings provide the first evidence supporting the role of miR-135b as an oncogene in CRC via the inhibition of TGFBR2 translation.

Natural humoral immune response to ribosomal P0 protein in colorectal cancer patients

Background

Tumor associated antigens are useful in colorectal cancer (CRC) management. The ribosomal P proteins (P0, P1, P2) play an important role in protein synthesis and tumor formation. The immunogenicity of the ribosomal P0 protein in head and neck, in breast and prostate cancer patients and the overexpression of the carboxyl-terminal P0 epitope (C-22 P0) in some tumors were reported.

Methods

Sera from 72 colorectal tumor patients (67 malignant and 5 benign tumors) were compared with 73 healthy donor sera for the presence of antibodies to CEA, EGFR, ErbB2 and ribosomal P proteins by western blotting or ELISA. Expression of the C-22 P0 epitope on tissues and colon cancer cells was determined by immunoperoxidase staining and indirect immunofluorescence/western blotting, respectively, employing MAb 2B2. Biological effects of MAb 2B2 on colon cancer cells were assessed by the Sulforhodamine B cell proliferation assay, trypan blue exclusion test and cleaved caspase-3 detection. Fisher’s exact test was used to compare the number of auto-antibodies positive patients with healthy donors. Variation in the C-22 P0 expression, and in the number of apoptotic cells was evaluated by Student’s t-test. Variation in cell survival and cell death was evaluated by Newman-Keuls test.

Results

No significant humoral response was observed to CEA, EGFR and ErbB2 in CRC patients. Conversely, 7 out of 67 CRC patient sera reacted to ribosomal P proteins. The prevalence of P proteins auto-antibodies in CRC patients was significant. Five patients showed restricted P0 immunoreactivity, while two patients reacted simultaneously to all P proteins. The C-22 P0 epitope was homogenously expressed both in malignant tumors and the adjacent mucosa, but the intensity of expression was higher in the tumor. Starved colon cancer cells showed a higher C-22 P0 epitope plasma membrane expression compared to control cells. MAb 2B2 inhibited colon cancer cell growth and induced cell death in a dose dependent manner.

Conclusions

Our study shows a spontaneous humoral immune response to ribosomal P0 protein in CRC patients and the inhibition of in vitro cancer cell growth after C-22 P0 epitope targeting. The ribosomal P0 protein might be a useful immunological target in CRC patients.

Adenoma detection rate in 41,010 patients from Southwest China

Adenoma detection rate (ADR) is considered as an important predictor of the risk of interval colorectal cancer following a screening colonoscopy. A retrospective review of all the patients who underwent colonoscopy in the First Affiliated Hospital of Guangxi Medical University (Nanning, China) between 2003 and 2012 was performed, with the aim of estimating the ADR in Southwest China and determine the effects of age, gender and polyp location on ADR. Demographic information and data regarding the timing of the colonoscopy, number of polyps removed, polyp location and pathological types of polyps were collected and analyzed. The patients were grouped according to colonoscopy date, polyp location, gender and age. The χ² test was used to compare the ADR between the different age and gender groups and the Cochran-Armitage trend test was used to calculate the statistical significance of the ADR trend across age groups. A two-tailed value of P<0.05 was considered to indicate statistically significant differences. A total of 41,010 patients were included, of whom 7,219 were diagnosed with at least one adenoma on pathological examination. Therefore, the ADR value of the 41,010 patients screened in the present study was 17.6%. There was a statistically significant trend of increasing ADR with increasing age in both genders (P<0.05). In addition, the ADR of male patients was significantly higher compared with that of female patients in all age groups (all P<0.05). The ADR of patients aged >50 years was significantly higher compared with that of patients aged <50 years (28.8 vs. 11.0%, respectively; P<0.05). In addition, 20% of the cases of detected adenomas occurred in the rectum, 47% in the left colon and 33% in the right colon.

Cell cycle kinetic analysis of colorectal neoplasms using a new automated immunohistochemistry-based cell cycle detection method

We have recently developed a new method called the immunohistochemistry-based cell cycle detection (iCCD), which allows the determination of cell cycle phases on a cell-by-cell basis. This automated procedure can be performed on tissue sections and involves triple immunostaining for geminin, cdt1, and γ H2A.X, which are nuclear proteins expressed sequentially, with a few overlaps, during the cell cycle. In the current study, we applied this technique to resected specimens of colorectal neoplasm to determine the usefulness of iCCD for the pathological examination of colorectal cancers. We examined 141 cases of colorectal cancers. Normal mucosa and adenomas were analyzed as controls. In nonneoplastic mucosa, we observed a pattern of distribution of the cells positive for these cell cycle markers. Adenomas showed a slight distortion in this pattern, the geminin-positive cells, indicative of S/G2/M phase, were localized in the upper one-third region of the crypts. In neoplastic mucosa, the marker expression pattern was disorganized. Compared with normal mucosa, colorectal neoplasms showed an increased proportion of geminin-positive cells and decreased percentages of cdt1-positive cells (G1 phase). However, we did not find significant difference in the expression pattern between adenomas and carcinomas. Cellular proportions were correlated with clinicopathological parameters such as microscopic vascular invasion and pT stages. In cases of preoperative adjuvant therapy, the proportion of geminin-positive cells decreased, whereas that of γ H2A.X-positive cells (indicative of apoptosis/degeneration) increased significantly. We believe that this novel method can be applied to clinical samples to evaluate cell cycle kinetics and the effects of preoperative adjuvant therapy in colorectal cancers.

Lack of association between human papillomavirus infection and colorectal cancer

Introduction

Colorectal cancer is the third leading cause of cancer-related deaths worldwide, with nearly one million new cases identified annually. Different factors might cause colorectal cancer, one of the most prevalent cancers among both men and women. Viral aetiology in cancerous malignancies is a very important issue and so far a number of viral strains have been identified as tumour oncogene viruses. Viral infections, such as human papillomavirus (HPV), have recently been suggested as a risk factor for colorectal cancer. However, the aetiology of the disease is still unknown.

Aim

To assessed the association between HPV infection and colorectal cancer.

Material and methods

In this study, 50 cancer tissue samples and 50 samples without colon cancer were studied in order to identify HPV through polymerase chain reaction (PCR). Of 42 adenocarcinomas, 10 were well differentiated, 30 moderated differentiated, and 2 were poorly differentiated. DNA extraction was verified by beta globin gene amplification; specific PCR was carried out based on HPV L1 consensus primers MY09/MY11.

Results

HPV DNA was not identified in any of the normal, adenocarcinoma, or adenoma samples.

Conclusions

In contrast with previous studies, the current research failed to establish a relationship between HPV infection and the incidence of colon cancer. Considering the existing inconsistencies, it is recommended that further studies be conducted with larger sample size.

Association Between Genetic Polymorphism of the MIF Gene and Colorectal Cancer in Taiwan

BACKGROUND

Colorectal cancer (CRC) is the highest leading cause of cancer-related mortality in Taiwan. Macrophage migration inhibitory factor (MIF) has recently been defined as a novel protumorigenic factor that promotes cell proliferation, migration, and invasion. The aim of the present study is to identify the association between MIF gene polymorphism and CRC.

METHODS

A case-control study was designed to test the hypothesis. A total of 192 biopsy-diagnosed CRC patients (CRC) and 256 healthy subjects (control) were recruited. Genotyping of four single nucleotide polymorphism (SNPs; rs755662, rs11548059, rs1049829, rs1803976) at chromosome positions 755662 (5' UTR), 11548059 (exon2), 1049829 (exon2), 1803976 (exon3) was performed using a Taqman SNP genotyping assay.

RESULTS

There is a significant difference in genotype frequency distribution of rs755662 polymorphism between CRC patients and controls (P = 0.011). No significant difference was found in the frequency distribution of rs11548059, rs1049829, rs1803976 polymorphism in CRC patients and controls (P = 0.660, P = 0.700, and P = 0.959, respectively). Moreover, the MIF-173 SNP was also significantly associated with young patients (age < 50 years, P = 0.026) late stage (Stage IV, P = 0.038) and poor differentiation group (P = 0.040). Compared to the control group, the MIF-173 SNP also significantly associated with patients with stages III and IV (P = 0.034 and 0.003, respectively).

CONCLUSION

The presence of MIF-173 (G/C) gene polymorphism (rs755662) was associated with susceptibility, patient age, and stages of CRC in Taiwanese.

Cytotoxic and apoptotic activities of Amorphophallus campanulatus (Roxb.) Bl. tuber extracts against human colon carcinoma cell line HCT-15

Colorectal cancer is one of the leading causes of cancer death worldwide and is the third most common form of malignancy in both men and women. Several possible colon cancer chemopreventive agents are found in edible plants. Amorphophallus campanulatus (Roxb.) Blume (family: Araceae) is a tuber crop, largely cultivated throughout the plains of India for using its corm as food. This tuber has also been traditionally used for the treatment of abdominal tumors, liver diseases, piles etc. The aim of this study was to evaluate the dose-dependent cytotoxic and apoptosis inducing effects of the sub fractions of A. campanulatus tuber methanolic extract (ACME) viz. petroleum ether fraction (PEF), chloroform fraction (CHF), ethyl acetate fraction (EAF) and methanolic fraction (MEF) on the colon cancer cell line, HCT-15. Antiproliferative effects of the sub fractions of ACME were studied by MTT assay. Apoptotic activity was assessed by DAPI, Annexin V-FITC and JC-1 fluorescent staining. The chemotherapeutic drug, 5-flurouracil (5-FU) was used as positive drug control. The sub fractions of ACME significantly inhibited the proliferation of HCT-15 cells in a dose-dependent manner. In addition, the extracts were found to induce apoptosis and were confirmed by DAPI, Annexin V-FITC and JC-1 fluorescent staining. A pronounced results of cytotoxic and apoptotic activities were observed in the cells treated with 5-FU and CHF, whereas, EAF and MEF treated cells exhibited a moderate result and the least effect was observed in PEF treated cells. Our results suggested that, among the sub fractions of ACME, CHF had potent cytotoxic and apoptotic activity and thus it could be explored as a novel target for anticancer drug development. Furthermore, these findings confirm that the sub fractions of ACME dose-dependently suppress the proliferation of HCT-15 cells by inducing apoptosis.

Organised colorectal cancer screening in Lampang Province, Thailand: preliminary results from a pilot implementation programme

OBJECTIVE

Colorectal cancer (CRC) is the third-most and fifth-most common cancer in men and women, in Thailand. The increasing CRC incidence and mortality can be reduced by screening and treating adenomas and early cancers. A pilot CRC screening programme using immunochemical faecal occult blood testing (iFOBT) and colonoscopy for test-positives were implemented through the routine Government Health Services in Lampang Province, to inform the acceptability, feasibility and scaling-up of screening in Thailand. This report describes the implementation, coverage and performance indicators of this project.

DESIGN

A target population aged 50-65 years was informed about and invited face to face to undergo CRC screening by community health workers (HWs). The HWs provided faecal sample collection kits and participants brought their samples to one of the primary health units or community hospitals where nurses performed iFOBT. iFOBT-positive persons were referred for colonoscopy at the Lampang cancer hospital, and endoscopic polypectomy/biopsies were performed according to the colonoscopic findings. Those with confirmed CRC received appropriate treatment.

RESULTS

Of the 127 301 target population, 62.9% were screened using iFOBT between April 2011 and November 2012. Participation was higher among women (67.8%) than men (57.8%) and lower in 50-54 year-old persons than in 60-65-year-olds. Of those screened, 873 (1.1%) were found positive; positivity was higher in men (1.2%) than in women (1.0%). To date 627 (72.0%) iFOBT-positive persons have had colonoscopy in which 3.7% had CRC and 30.6% had adenomas.

CONCLUSIONS

The successful implementation of the pilot CRC screening with satisfactory process measures indicate the feasibility of scaling-up organised CRC screening through existing health services in Thailand.

In vivo analysis of insulin-like growth factor type 1 receptor humanized monoclonal antibody MK-0646 and small molecule kinase inhibitor OSI-906 in colorectal cancer

The development and characterization of effective anticancer drugs against colorectal cancer (CRC) is of urgent need since it is the second most common cause of cancer death. The study was designed to evaluate the effects of two IGF-1R antagonists, MK-0646, a recombinant fully humanized monoclonal antibody and OSI-906, a small molecule tyrosine kinase inhibitor on CRC cells. Xenograft study was performed on IGF-1R-dependent CRC cell lines for analyzing the antitumor activity of MK-0646 and OSI-906. Tumor proliferation and apoptosis were assessed using Ki67 and TUNEL assays, respectively. We also performed in vitro characterization of MK-0646 and OSI-906 treatment on CRC cells to identify mechanisms associated with drug-induced cell death. Exposure of the GEO and CBS tumor xenografts to MK-0646 or OSI-906 led to a decrease in tumor growth. TUNEL analysis showed an increase of approximately 45-55% in apoptotic cells in both MK-0646 and OSI-906 treated tumor samples. We report the novel finding that treatment with IGF-1R antagonists led to downregulation of X-linked inhibitor of apoptosis (XIAP) protein involved in cell survival and inhibition of cell death. In conclusion, IGF-1R antagonists (MK-0646 and OSI-906) demonstrated single agent inhibition of subcutaneous CRC xenograft growth. This was coupled to pro-apoptotic effects resulting in downregulation of XIAP and inhibition of cell survival. We report a novel mechanism by which MK-0646 and OSI-906 elicits cell death in vivo and in vitro. Moreover, these results indicate that MK-0646 and OSI-906 may be potential anticancer candidates for the treatment of patients with IGF-1R-dependent CRC.

Aberrant O-GlcNAc-modified proteins expressed in primary colorectal cancer

O-GlcNAcylation is a post-translational modification of serine and threonine residues which is dynamically regulated by 2 enzymes; O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) that catalyze the addition and removal of a single N-acetylglucosamine (GlcNAc) molecule, respectively. This modification is thought to be a nutrient sensor in highly proliferating cells via the hexosamine biosynthesis pathway, a minor branch of glycolysis. Although emerging evidence suggests that O-GlcNAc modification is associated with many types of cancer, identification of O-GlcNAc-modified proteins and their role in cancer remain unexplored. In the present study, we demonstrated that O-GlcNAcylation is increased in primary colorectal cancer tissues, and that this augmentation is associated with an increased expression of OGT levels. Using 2-dimensional O-GlcNAc immunoblotting and LC-MS/MS analysis, 16 proteins were successfully identified and 8 proteins showed an increase in O-GlcNAcylation, including cytokeratin 18, heterogeneous nuclear ribonucleoproteins A2/B1 (hnRNP A2/B1), hnRNP H, annexin A2, annexin A7, laminin-binding protein, α-tubulin and protein DJ-1. Among these identified proteins, annexin A2 was further confirmed to show overexpression of O-GlcNAc in all cancer samples. The results, therefore, indicate that aberrant O-GlcNAcylation of proteins is associated with colorectal cancer and that identification of O-GlcNAc-modified proteins may provide novel biomarkers of cancer.

Alantolactone induces apoptosis in RKO cells through the generation of reactive oxygen species and the mitochondrial pathway

Alantolactone, a methanol extract of Inula helenium, possesses anticancer properties in a number of cancer cell lines. However, its anticancer effect on human colorectal cancer cells and the underlying mechanisms remain to be elucidated. In the present study, the effects of alantolactone on cell viability and apoptosis in RKO human colon cancer cells were investigated. Alantolactone treatment of RKO cells was found to result in dose‑dependent inhibition of cell viability and induction of apoptosis, accompanied with the accumulation of reactive oxygen species (ROS) and the disruption of mitochondrial membrane potential. In addition, these effects were blocked with N‑acetylcysteine, a specific ROS inhibitor. Western blotting indicated that exposure of RKO cells to alantolactone is associated with the downregulation of Bcl‑2, induction of Bax and activation of caspase‑3 and ‑9. These results indicated that a ROS‑mediated mitochondria‑dependent pathway is involved in alantolactone‑induced apoptosis. From these observations, it was hypothesized that alantolactone may be used for the treatment of human colon cancer.

Cited1 deficiency suppresses intestinal tumorigenesis

Conditional deletion of Apc in the murine intestine alters crypt-villus architecture and function. This process is accompanied by multiple changes in gene expression, including upregulation of Cited1, whose role in colorectal carcinogenesis is unknown. Here we explore the relevance of Cited1 to intestinal tumorigenesis. We crossed Cited1 null mice with Apc(Min/+) and AhCre(+)Apc(fl/fl) mice and determined the impact of Cited1 deficiency on tumour growth/initiation including tumour multiplicity, cell proliferation, apoptosis and the transcriptome. We show that Cited1 is up-regulated in both human and murine tumours, and that constitutive deficiency of Cited1 increases survival in Apc(Min/+) mice from 230.5 to 515 days. However, paradoxically, Cited1 deficiency accentuated nearly all aspects of the immediate phenotype 4 days after conditional deletion of Apc, including an increase in cell death and enhanced perturbation of differentiation, including of the stem cell compartment. Transcriptome analysis revealed multiple pathway changes, including p53, PI3K and Wnt. The activation of Wnt through Cited1 deficiency correlated with increased transcription of β-catenin and increased levels of dephosphorylated β-catenin. Hence, immediately following deletion of Apc, Cited1 normally restrains the Wnt pathway at the level of β-catenin. Thus deficiency of Cited1 leads to hyper-activation of Wnt signaling and an exaggerated Wnt phenotype including elevated cell death. Cited1 deficiency decreases intestinal tumourigenesis in Apc(Min/+) mice and impacts upon a number of oncogenic signaling pathways, including Wnt. This restraint imposed by Cited1 is consistent with a requirement for Cited1 to constrain Wnt activity to a level commensurate with optimal adenoma formation and maintenance, and provides one mechanism for tumour repression in the absence of Cited1.

Autosomal mutations in mouse kidney epithelial cells exposed to high-energy protons in vivo or in culture

Proton exposure induces mutations and cancer, which are presumably linked. Because protons are abundant in the space environment and significant uncertainties exist for the effects of space travel on human health, the purpose of this study was to identify the types of mutations induced by exposure of mammalian cells to 4-5 Gy of 1 GeV protons. We used an assay that selects for mutations affecting the chromosome 8-encoded Aprt locus in mouse kidney cells and selected mutants after proton exposure both in vivo and in cell culture. A loss of heterozygosity (LOH) assay for DNA preparations from the in vivo-derived kidney mutants revealed that protons readily induced large mutational events. Fluorescent in situ hybridization painting for chromosome 8 showed that >70% of proton-induced LOH patterns resembling mitotic recombination were in fact the result of nonreciprocal chromosome translocations, thereby demonstrating an important role for DNA double-strand breaks in proton mutagenesis. Large interstitial deletions, which also require the formation and resolution of double-strand breaks, were significantly induced in the cell culture environment (14% of all mutants), but to a lesser extend in vivo (2% of all mutants) suggesting that the resolution of proton-induced double-strand breaks can differ between the intact tissue and cell culture microenvironments. In total, the results demonstrate that double-strand break formation is a primary determinant for proton mutagenesis in epithelial cell types and suggest that resultant LOH for significant genomic regions play a critical role in proton-induced cancers.

Expression of OV-6 in primary colorectal cancer and rectal cancer with preoperative chemoradiotherapy: a clinicopathological study

AIMS

OV-6 is among the best available markers of liver stem cells. The aim of this study was to investigate OV-6 expression and its clinical implications in colorectal cancer.

METHODS AND RESULTS

Expression of OV-6 and its clinical implications were investigated in 94 patients with American Joint Committee on Cancer (AJCC) stage I-III primary colorectal cancer and in 37 rectal cancer patients who had received preoperative chemoradiotherapy. The two main expression patterns of OV-6 were cytoplasmic and membranous. Overexpression of OV-6, which was identified on the basis of overall staining intensity, was associated with perineural invasion, lymphovascular invasion, and early relapses. Membranous OV-6 overexpression was also significantly associated with depth of tumour invasion, AJCC stage, lymphovascular and perineural invasion, and postoperative early relapse. Disease-free survival and overall survival were significantly poorer in patients with high overall OV-6 expression than in those with low overall OV-6 expression (P = 0.015 and P = 0.029, respectively), and significantly poorer in patients with high membranous OV-6 expression than in those with low membranous OV-6 expression (P < 0.001 and P < 0.001, respectively). Membranous OV-6 expression was a more reliable prognostic marker than overall expression.

CONCLUSIONS

OV-6 is not unique to the hepatobiliary system, and may be a novel prognostic marker in colorectal cancer.

What are the best routes to effectively model human colorectal cancer?

Colorectal cancer (CRC) is the third most common cancer in the UK, with over 37,500 people being diagnosed every year. Survival rates for CRC have doubled in the last 30 years and it is now curable if diagnosed early, but still over half of all sufferers do not survive for longer than 5 years after diagnosis. The major complication to treating this disease is that of metastasis, specifically to the liver, which is associated with a 5 year survival of less than 5%. These statistics highlight the importance of the development of earlier detection techniques and more targeted therapeutics. The future of treating this disease therefore lies in increasing understanding of the mutations which cause tumourigenesis, and insight into the development and progression of this complex disease. This can only be achieved through the use of functional models which recapitulate all aspects of the human disease. There is a wide range of models of CRC available to researchers, but all have their own strengths and weaknesses. Here we review how CRC can be modelled and discuss the future of modelling this complex disease, with a particular focus on how genetically engineered mouse models have revolutionised this area of research.

Role of SALL4 in the progression and metastasis of colorectal cancer

Background

Human cancer cells resemble stem cells in expression signatures leading them to share some features, most notably, self-renewal. A complex network of transcription factors and signaling molecules are required for continuance of this trait. SALL4 is a zinc finger transcriptional activator crucial for maintenance of self-renewal in stem cells; however, its expression level has not yet been elucidated in colorectal tumor cells. To determine this level and probable clinicopathological consequences, its expression was analyzed.

Methods

SALL4 expression in fresh tumoral and distant tumor-free tissues from 46 colorectal samples was compared by real-time polymerase chain reaction (PCR).

Results

Greater than a two-fold increase in SALL4 expression was detected in 87% of tumors vs. normal related tissues. SALL4 expression was significantly correlated with tumor cell metastasis to lymph nodes, especially in moderately-differentiated tumor samples (P < 0.05). Furthermore, higher levels of SALL4 mRNA expression were significantly associated with younger than older patients with tumor cells in stages I and II (P < 0.05).

Conclusions

These results indicate a relationship between SALL4 expression and tumor cell metastasis to lymph nodes and consequent advancement of tumors to advanced stages III and IV. Along with the promising evidence of its role in self-renewal in various cancers, SALL4 may have a role in progression, development and maintenance of colorectal cancers.

Role of the IL-6-JAK1-STAT3-Oct-4 pathway in the conversion of non-stem cancer cells into cancer stem-like cells

Previous studies have demonstrated that a small subset of cancer cells is capable of tumor initiation. The existence of tumor initiating cancer stem cells (CSCs) has several implications in terms of future cancer treatment and therapies. However, recently, several researchers proposed that differentiated cancer cells (non-CSCs) can convert to stem-like cells to maintain equilibrium. These results imply that removing CSCs may prompt non-CSCs in the tumor to convert into stem cells to maintain the equilibrium. Interleukin-6 (IL-6) has been found to play an important role in the inducible formation of CSCs and their dynamic equilibrium with non-stem cells. In this study, we used CSC-like human breast cancer cells and their alternate subset non-CSCs to investigate how IL-6 regulates the conversion of non-CSCs to CSCs. MDA-MB-231 and MDA-MB-453 CSC-like cells formed mammospheres well, whereas most of non-stem cells died by anoikis and only part of the remaining non-stem cells produced viable mammospheres. Similar results were observed in xenograft tumor formation. Data from cytokine array assay show that IL-6 was secreted from non-CSCs when cells were cultured in ultra-low attachment plates. IL-6 regulates CSC-associated OCT-4 gene expression through the IL-6-JAK1-STAT3 signal transduction pathway in non-CSCs. Inhibiting this pathway by treatment with anti-IL-6 antibody (1 μg/ml) or niclosamide (0.5-2 μM)/LLL12 (5-10 μM) effectively prevented OCT-4 gene expression. These results suggest that the IL-6-JAK1-STAT3 signal transduction pathway plays an important role in the conversion of non-CSCs into CSCs through regulation of OCT-4 gene expression.

Characteristics of CD44 alternative splice pattern in the course of human colorectal adenocarcinoma progression

BACKGROUND

CD44 is considered as 'a' metastasis associated gene, despite the fact that it is an umbrella term for a group of molecules produced from a single gene by alternative splicing. However, little consideration is given to the above in the literature of colorectal carcinomas as well as other tumour types, leading to confusion and contradictory results about its possible role in tumour progression.

METHODS

We compared the CD44 alternative splice pattern (ASP) of three genetically different human colorectal cancer cell lines (HT25, HT29, HCT116) using a series of PCR reactions and next- generation sequencing method, as well as identified a colorectal adenocarcinoma specific CD44 ASP. This ASP was further investigated in terms of its qualitative and quantitative stability in our experimental iso- and xenograft mouse models for colorectal cancer progression. A complex preclinical experimental set-up was established to separately test the different steps of tumour progression and the role of tumour microenvironment, respectively, focusing on the role of 'CD44' in this process.

RESULTS

We managed to present a colorectal cancer-specific CD44 ASP, which remained unchanged from cell lines throughout primary tumour formation and metastatic progression. Furthermore, we report a unique roster of all expressed CD44 variant isoforms characteristic to colorectal cancer. Finally, on quantitative assessment of the variable exons v3 and v6, higher co-expression levels were found to be characteristic to metastatically potent tumour cells.

CONCLUSION

Particular CD44 variant isoforms seem to act as "metastasis genes" via tumour microenvironment-driven shifts in v3 and v6 expressions. However, this function may just affect a minority of tumour subclones. This fact and the huge potential number of different CD44 splice variants that can contain v3 and v6 domains can explain incoherence of clinical studies regarding functional asessment of CD44 variants, as well as diminish the chances of using CD44 variants for predictive purpose.

Genetic and epigenetic alterations in primary colorectal cancers and related lymph node and liver metastases

BACKGROUND

Colorectal cancer (CRC) prognosis and survival are strictly related to the development of distant metastases. New targeted therapies have increased patient survival, but the objective response rate is still very limited, partially because of a traditional focus on designing treatment according to the molecular profile of the primary tumor regardless the diversity between the primary tumor and metastases. The objective of this study was to evaluate the presence of molecular heterogeneity during metastatic progression and its potential impact on clinical treatment.

METHODS

The authors analyzed v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) codon 12 mutations, the v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) thymine to adenine substitution at codon 1788, and tumor protein 53 (p53) mutations and investigated promoter methylation of Ras association (RalGDS/AF-6) domain family member 1 protein (RASSF1a), E-cadherin, and cyclin-dependent kinase inhibitor 2A (p16INK4a) in 101 primary CRCs (67 stage III and 34 stage IV) and related lymph node and liver metastases.

RESULTS

Lymph node metastases were characterized by fewer alterations compared with primary tumors and liver metastases, especially KRAS (P = .03) and p16INK4a (P = .05). Genetic changes, when detectable in metastases, mostly were retained from the primary tumor, whereas epigenetic changes more frequently were acquired de novo. Overall, 31 distinct CRC molecular profiles were detected, none of which characterized a particular tumor stage. When the metastatic lesions also were included in the profiles, there were 53 distinct molecular profiles in 67 patients with stage III disease and 34 distinct molecular profiles in 34 patients with stage IV disease.

CONCLUSIONS

Lymph node and liver metastases appear to originate in clonally different processes, with more molecular alterations occurring in distant metastases than in lymph node metastases and with elevated heterogeneity of the primary tumor. Thus, potential prognostic targets should be carefully evaluated for their heterogeneity in both primary tumors and distant metastases to avoid erroneous misclassification.

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.

Bile salts increase epithelial cell proliferation through HuR-induced c-Myc expression

BACKGROUND

Bile salts increase intestinal mucosal proliferation through an increase in c-Myc, a transcription factor that controls the expression of numerous translation regulatory proteins. HuR is an RNA-binding protein that regulates translation of target mRNAs. RNA-binding proteins can control mRNA stability by binding to AU- and U-rich elements located in the 3'-untranslated regions (3'-UTRs) of target mRNAs.

AIM

To determine how bile salt-induced c-Myc stimulates enterocyte proliferation.

METHODS

Enterocyte proliferation was measured both in vivo using C57Bl6 mice and in vitro using IEC-6 cells after taurodeoxycholate (TDCA) supplementation. HuR and c-Myc protein expression was determined by immunoblot. c-Myc mRNA expression was determined by PCR. HuR expression was inhibited using specific small interfering RNA. HuR binding to c-Myc mRNA was determined by immunoprecipitation.

RESULTS

TDCA increased enterocyte proliferation in vivo and in vitro. TDCA stimulates translocation of HuR from the nucleus to the cytoplasm. Cytoplasmic HuR regulates c-Myc translation by HuR binding to the 3'-UTR of c-Myc mRNA. Increased TDCA-induced c-Myc increases enterocyte proliferation.

CONCLUSIONS

Bile salts have beneficial effects on the intestinal epithelial mucosa, which are important in maintaining intestinal mucosal integrity and function. These data further support an important beneficial role of bile salts in regulation of mucosal growth and repair. Decreased enterocyte exposure to luminal bile salts, as occurs during critical illness, liver failure, starvation, and intestinal injury, may have a detrimental effect on mucosal integrity.

Role of canonical Wnt signaling in endometrial carcinogenesis

While the role of Wnt signaling is well established in colorectal carcinogenesis, its function in gynecologic cancers has not been elucidated. Here, we describe the current state of knowledge of canonical Wnt signaling in endometrial cancer (EC), and its implications for future therapeutic targets. Deregulation of the Wnt/β-catenin signaling pathway in EC occurs by inactivating β-catenin mutations in approximately 10-45% of ECs, and via downregulation of Wnt antagonists by epigenetic silencing. The Wnt pathway is intimately involved with estrogen and progesterone, and emerging data implicate it in other important signaling pathways, such as mTOR and Hedgehog. While no therapeutic agents targeting the Wnt signaling pathway are currently in clinical trials, the preclinical data presented suggest a role for Wnt signaling in uterine carcinogenesis, with further research warranted to elucidate the mechanism of action and to proceed towards targeted cancer drug development.

P53 gene mutation increases progastrin dependent colonic proliferation and colon cancer formation in mice

Transgenic mice overexpressing human progastrin (hGAS) show colonic crypt hyper-proliferation and elevated susceptibility to colon carcinogenesis. We aimed to investigate effects of p53 mutation on colon carcinogenesis in hGAS mice. We show that introducing a p53 gene mutation further increases progastrin dependent BrdU labeling and results in markedly elevated number of aberrant crypt foci (ACF) and colonic tumors. We demonstrate that hGAS/Lgr5-GFP mice have higher number of Lgr5+ colonic stem cells per crypt when compared to Lgr5-GFP mice indicating that progastrin changes crypt biology through increased stem cell numbers and additional p53 mutation leads to more aggressive phenotype in this murine colon cancer model.

Immune microenvironmental shift along human colorectal adenoma-carcinoma sequence: is it relevant to tumor development, biomarkers and biotherapeutic targets?

Human colorectal carcinoma (CRC) is one of the leading cancers. Every year, the WHO estimates a total of 945,000 new CRC cases, with 492,000 deaths worldwide. Most CRCs arise from the main premalignant lesion, colorectal adenomas, and the progression of colorectal adenoma to CRCs may take a long-term time course. The development of human CRCs is not only determined by the adenomatous cells, but also by the interaction between adenomatous cells and host immune environment. In response to tumor initiation or invasion, many inflammatory cells and components will be inevitably activated and form an inflammatory microenvironment surrounding the CRC tumors. Accumulative evidence has revealed that inflammatory response plays a key role in the development of human CRCs by implicating in many aspects including in determining the microenvironmental immune function shift from immunosurveillance to immunosuppression and significantly influences the progression of precancerous lesions to cancers. In this review, the functional changes of immune microenvironment from precancerous stage (adenoma) to cancer stage are summarized, and their potential as predictive biomarkers and biotherapeutic significance in preventing the development of CRCs are discussed.

RAS Mutations and Oncogenesis: Not all RAS Mutations are Created Equally

Mutation in RAS proteins is one of the most common genetic alterations observed in human and experimentally induced rodent cancers. In vivo, oncogenic mutations have been shown to occur at exons 12, 13, and 61, resulting in any 1 of 19 possible point mutations in a given tumor for a specific RAS isoform. While some studies have suggested a possible role of different mutant alleles in determining tumor severity and phenotype, no general consensus has emerged on the oncogenicity of different mutant alleles in tumor formation and progression. Part of this may be due to a lack of a single, signature pathway that shows significant alterations between different mutations. Rather, it is likely that subtle differences in the activation, or lack thereof, of downstream effectors by different RAS mutant alleles may determine the eventual outcome in terms of tumor phenotype. This paper reviews our current understanding of the potential role of different RAS mutations on tumorigenesis, highlights studies in model cell culture and in vivo systems, and discusses the potential of expression array and computational network modeling to dissect out differences in activated RAS genes in conferring a transforming phenotype.

Role of hesperetin (a natural flavonoid) and its analogue on apoptosis in HT-29 human colon adenocarcinoma cell line--a comparative study

Colon cancer is one of the serious health problems in most developed countries and its incidence rate is increasing in India. Hesperetin (HN) (3',5,7-trihydroxy-4'-methoxyflavonone) and hesperetin analogue (HA) were tested for their apoptosis inducing ability. Methyl thiazolyl tetrazolium assay revealed a dose as well as duration-dependent reduction of HT-29 (colon adenocarcinoma) cellular growth in response to HN and HA treatment. At 24 h 70 μM of HN and 32 μM of HA showed 50% reduction of HT-29 cellular growth. Acridine orange/ethidium bromide staining showed apoptotic features of cell death induced by HN and HA. Rhodamine 123 staining showed significant reduction in mitochondrial membrane potential induced by HN and HA. HN and HA induced DNA damage was confirmed by comet tail formation. Lipid peroxidation markers (TBARS) and protein oxidation marker (PCC) were significantly elevated in HN and HA treated groups. Enzymic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were slightly decreased in their activities compared to control (untreated HT-29 cells). Results of Western blot analysis of apoptosis associated genes revealed an increase in cytochrome C, Bax, cleaved caspase-3 expression and a decrease in Bcl-2 expression. These findings indicate that HN and HA induce apoptosis on HT-29 via Bax dependent mitochondrial pathway involving oxidant/antioxidant imbalance.

Association of Helicobacter pylori infection with the development of colorectal polyps and colorectal carcinoma

BACKGROUND AND AIMS

Recent studies have suggested a possible association between Helicobacter pylori (HP) infection and colon neoplasia. HP infection causes hypergastrinemia, and gastrin increases colorectal mucosal proliferation, potentially leading to colorectal cancer. We investigated whether HP infection is associated with colon neoplasia.

METHODS

We conducted a cross-sectional, single-center study in which patients who underwent routine outpatient colonoscopy and were tested for HP infection on esophagogastroduodenoscopy from January 1, 2008 to November 1, 2009 were identified. Patient demographic data (gender and age) and information on colon polyp characteristics (size, number of polyps, location, morphology, and histology) were abstracted from retrospective chart review. Presence of adenoma/carcinoma was compared in the HP-positive cases and HP-negative controls.

RESULTS

A total of 192 patients were included in the study, with 96 patients each in the HP-positive and -negative groups. The two groups did not differ significantly in gender, age, polyp size, number of polyps, polyp location, morphology, and histology. Adenomatous colon polyps were noted in 31% of the HP-positive cases and in 26% of the HP-negative controls (P = 0.52). Colon carcinoma was found in 6% of HP-positive and 2% of HP-negative patients (P = 0.28).

CONCLUSION

The higher prevalence of adenomatous colon polyps/carcinoma in HP-positive patients compared to HP-negative patients was not statistically significant. Larger studies are needed to examine further the potential association between HP infection and colorectal adenoma/carcinoma.