Etiology Of Colon Cancer Research Articles

The Mediating Role of Comorbidities on the Relationship Between Serum Vitamin D and Five-Year Mortality Risk in Colon Cancer Patients

This retrospective cohort study explores the relationship between vitamin D levels and 5-year mortality risk among 1,549 colon cancer patients seen at University of California health centers between 2012 and 2019, with a particular focus on the mediating role of comorbidities. Methods leveraged structural equation modeling to assess both direct and indirect pathways linking vitamin D to mortality risk. This analysis revealed a protective direct effect of higher vitamin D levels against mortality risk. Additionally, this study uncovered an indirect pathway, demonstrating that vitamin D lowers mortality risk by mitigating comorbidity, which subsequently influence mortality risk. Study results indicate that approximately 9.2% of the beneficial effect of vitamin D on mortality risk is attributable to its capacity to reduce comorbidity burden. In disaggregated and confounder-adjusted structural modeling, there were significant indirect effects for 25(OH)D on mortality risk through its effects on depression and obesity but not on anxiety, diabetes, or chronic kidney disease. These results suggest that the protective effects of vitamin D in colon cancer etiology appear to be through direct action on cancer progression, though patients who also suffer from depression and obesity would especially benefit from achieving adequate levels of serum vitamin D.

The Role of Wheatgrass in Colorectal Cancer: A Review of the Current Evidence.

The etiology of colon cancer is either genetic in nature or results from inflammatory bowel diseases such as ulcerative colitis and Crohn's disease; nevertheless, dietary habits play a crucial role in the disease. Wheatgrass is a dietary supplement that is rich in vitamins, minerals, and antioxidants which contribute to health promotion in cardiovascular diseases, liver disease, blood diseases, diabetes, and inflammatory bowel diseases, as well as in several types of cancers, such as oral squamous cell cancer, cervical cancer, and breast cancer. In colorectal cancer (CRC), the prospect that wheatgrass possesses anti-inflammatory, antioxidant, and anticancer properties, and its use as an adjunctive therapy, have been minimally investigated and evidence is still limited. In this review, we compiled the available evidence pertaining to wheatgrass and its likely impact on CRC, described the pathways of inflammation in which wheatgrass could possibly play a role, and identified future research needs on the subject.

Synthesis and Biological Evaluation of Some New 3-Aryl-2-thioxo-2,3-dihydroquinazolin-4(1H)-ones and 3-Aryl-2-(benzylthio)quinazolin-4(3H)-ones as Antioxidants; COX-2, LDHA, α-Glucosidase and α-Amylase Inhibitors; and Anti-Colon Carcinoma and Apoptosis-Inducing Agents.

Oxidative stress, COX-2, LDHA and hyperglycemia are interlinked contributing pathways in the etiology, progression and metastasis of colon cancer. Additionally, dysregulated apoptosis in cells with genetic alternations leads to their progression in malignant transformation. Therefore, quinazolinones 3a-3h and 5a-5h were synthesized and evaluated as antioxidants, enzymes inhibitors and cytotoxic agents against LoVo and HCT-116 cells. Moreover, the most active cytotoxic derivatives were evaluated as apoptosis inducers. The results indicated that 3a, 3g and 5a were efficiently scavenged DPPH radicals with lowered IC50 values (mM) ranging from 0.165 ± 0.0057 to 0.191 ± 0.0099, as compared to 0.245 ± 0.0257 by BHT. Derivatives 3h, 5a and 5h were recognized as more potent dual inhibitors than quercetin against α-amylase and α-glucosidase, in addition to 3a, 3c, 3f and 5b-5f against α-amylase. Although none of the compounds demonstrated a higher efficiency than the reference inhibitors against COX-2 and LDHA, 3a and 3g were identified as the most active derivatives. Molecular docking studies were used to elucidate the binding affinities and binding interactions between the inhibitors and their target proteins. Compounds 3a and 3f showed cytotoxic activities, with IC50 values (µM) of 294.32 ± 8.41 and 383.5 ± 8.99 (LoVo), as well as 298.05 ± 13.26 and 323.59 ± 3.00 (HCT-116). The cytotoxicity mechanism of 3a and 3f could be attributed to the modulation of apoptosis regulators (Bax and Bcl-2), the activation of intrinsic and extrinsic apoptosis pathways via the upregulation of initiator caspases-8 and -9 as well as executioner caspase-3, and the arrest of LoVo and HCT-116 cell cycles in the G2/M and G1 phases, respectively. Lastly, the physicochemical, medicinal chemistry and ADMET properties of all compounds were predicted.

A Comprehensive Study on the Anti-cancer Effects of Quercetin and Its Epigenetic Modifications in Arresting Progression of Colon Cancer Cell Proliferation

Colon cancer etiology involves a wide spectrum of genetic and epigenetic alterations, finding it challenging to find effective therapeutic strategies. Quercetin exhibits potent anti-proliferative/apoptotic properties. In the present study, we aimed to elucidate the anti-cancer and anti-aging effect of quercetin in colon cancer cell lines. The anti-proliferative effect of quercetin was assessed in vitro by CCK-8 in normal and colon cancer cell lines. To check the anti-aging potential of quercetin, collagenase, elastase, and hyaluronidase inhibitory activity assays were performed. The epigenetic and DNA damage assays were performed using the human NAD-dependent deacetylase Sirtuin-6, proteasome 20S, Klotho, Cytochrome-C, and telomerase ELISA kits. Furthermore, the aging-associated miRNA expression profiling was performed on colon cancer cells. The treatment with quercetin inhibited cell proliferation of colon cancer cells in a dose-dependent manner. Quercetin arrested colon cancer cell growth by modulating expression of aging proteins including Sirtuin-6 and Klotho and also by inhibiting telomerase activity to restrict the telomere length which is evident from qPCR analysis. Quercetin also exhibited DNA damage protection by reducing proteasome 20S levels. The miRNA expression profiling results displayed differential expression of miRNA in colon cancer cell, and in addition, the highly upregulated miRNA was involved in the regulation of cell cycle, proliferation, and transcription. Our data suggest that quercetin treatment inhibited cell proliferation in colon cancer cells through regulating the anti-aging protein expression and provides better understanding for quercetin’s potential use in colon cancer treatment.

Polymorphisms in the mTOR-PI3K-Akt pathway, energy balance-related exposures and colorectal cancer risk in the Netherlands Cohort Study

BackgroundThe mTOR-PI3K-Akt pathway influences cell metabolism and (malignant) cell growth. We generated sex-specific polygenic risk scores capturing natural variation in 7 out of 10 top-ranked genes in this pathway. We studied the scores directly and in interaction with energy balance-related factors (body mass index (BMI), trouser/skirt size, height, physical activity, and early life energy restriction) in relation to colorectal cancer (CRC) risk in the Netherlands Cohort Study (NLCS) (n=120,852). The NLCS has a case-cohort design and 20.3 years of follow-up. Participants completed a baseline questionnaire on diet and cancer in 1986 when 55–69 years old. ~75% of the cohort returned toenail clippings used for DNA isolation and genotyping (n subcohort=3,793, n cases=3,464). To generate the scores, the dataset was split in two and risk alleles were defined and weighted based on sex-specific associations with CRC risk in the other dataset half, because there were no SNPs in the top-ranked genes associated with CRC risk in previous genome-wide association studies at a significance level p<1*10−5.ResultsCox regression analyses showed positive associations between the sex-specific polygenic risk scores and colon but not rectal cancer risk in men and women, with hazard ratios for continuously modeled scores close to 1.10. There was no modifying effect observed of the scores on associations between the energy balance-related factors and CRC risk. However, BMI (in men), non-occupational physical activity (in women), and height (in men and women) were associated with the risk of CRC, in particular (proximal and distal) colon cancer, in the direction as expected in the lower tertiles of the sex-specific polygenic risk scores.ConclusionsCurrent data suggest that the mTOR-PI3K-Akt pathway may be involved in colon cancer development. This study thereby sheds more light on colon cancer etiology through use of genetic variation in the mTOR-PI3K-Akt pathway.

The Association of Diet-Modulated Gut Microbiota on Development and Treatment of Colorectal Cancer

Colorectal cancer is the third most common cancer worldwide. Etiology of colon cancer continues to be investigated with research fndings ranging from environment to diet to inherited gene mutations. Risk factors associated with colon cancer include familial history of colon cancer and inflammatory bowel disease, as well as lifestyle-related modifiable influences like diet, weight, and exercise. Recent findings point to the connection between diet and gut microbiota, which is highly affected by changes in diet promoting either an environment of beneficial bacteria or dysbiosis. Dietary effects on the microbiome can impact health outcomes, including an increased risk for colorectal cancer. Although the mechanisms behind the effect of gut microbiota on the development of colorectal cancer continues to evolve, its effect on both inflammation and immune response may play a key role. Further, after development of colorectal cancer diagnosis, the changes to gut microbiota have a potential to continue to influence the effectiveness of therapy and treatment. This review presents the current knowledge around the diet-modulated gut microbiome and its association with, risk for, development of, and treatment of colorectal cancer. Overall, further research on dietary elements that affect the gut microbiome and its subsequent effect on development and treatment of colorectal cancer is needed for applicable recommendations that can be made for dietary modulation of the gut microbiota for improved health outcomes.

Utility of KRAS Gene and Clinicopathological Features in the Assessment of the Risk of Type 2 Diabetes in the Etiology of Colon Cancer.

Background Cancer and diabetes have a tremendous impact on health globally. This study aimed to evaluate the KRAS gene in colon cancer tissues obtained from patients with type 2 diabetes mellitus (T2DM). Materials and Methods Data from 315 cases (156 colon diabetics and 159 patients were nondiabetics) were retrospectively retrieved. mRNA from surgically resected colon cancer tumors were also retrieved. Results The expression of KRAS mRNA was significantly higher in patients afflicted with T2DM than nondiabetic patients. The KRAS mRNA levels were significantly amplified from primary to metastatic lesions ( p < 0.001). Conclusion The association between T2DM and colon cancer was well-established in the present study.

Analysis of Salmonella typhimurium Protein-Targeting in the Nucleus of Host Cells and the Implications in Colon Cancer: An in-silico Approach.

BackgroundInfections of Salmonella typhimurium (S. typhimurium) are major threats to health, threats include diarrhoea, fever, acute intestinal inflammation, and cancer. Nevertheless, little information is available about the involvement of S. typhimurium in colon cancer etiology.MethodsThe present study was designed to predict nuclear targeting of S. typhimurium proteins in the host cell through computational tools, including nuclear localization signal (NLS) mapper, Balanced Subcellular Localization predictor (BaCeILo), and Hum-mPLoc using next-generation sequencing data.ResultsSeveral gene expression-associated proteins of S. typhimurium have been predicted to target the host nucleus during intracellular infections. Nuclear targeting of S. typhimurium proteins can lead to competitive interactions between the host and pathogen proteins with similar cellular substrates, and it may have a possible involvement in colon cancer growth. Our results suggested that S. typhimurium releases its proteins within compartments of the host cell, where they act as a component of the host cell proteome. Protein targeting is possibly involved in colon cancer etiology during intracellular bacterial infection.ConclusionThe results of current in-silico study showed the potential involvement of S. typhimurium infection with alteration in normal functioning of host cell which act as possible factor to connect with the growth and development of colon cancer.

Abstract A40: Induction of oxidative/nitrosative stress, proinflammatory cytokines and dysregulation of Wnt/beta-catenin signaling by benzo(a)pyrene in colons of BALB/c mice

Abstract Epidemiologic surveys and experimental data have revealed that environmental and dietary factors contribute to the etiology of colon cancer, which ranks third in cancer-related mortalities in the United States and fourth worldwide. In particular, human diet containing environmental carcinogens such as benzo(a)pyrene (B(a)P), a polycyclic aromatic hydrocarbon, has been the focus of investigators recently in relation to generated interest in looking at how it exerts its colorectal cancer. The present study investigated the effects of B(a)P on biomarkers of oxidative stress, inflammation and Wnt-signaling in colon of BALB/c mice following exposure to varying doses of 62.5, 125, and 250 mg/kg B(a)P for 7 days by oral gavage. Exposure to B(a)P induced marked oxidative stress accompanied by decrease in the colonic antioxidant enzyme activities and glutathione level with concomitant increase in myeloperoxidase activity, nitric oxide, and lipid peroxidation levels. Colon histopathology results showed B(a)P-related lesions characterized by atrophy, mucosal ulceration, and gland erosion in the mice. Immunohistochemistry analysis showed that B(a)P treatment increased the protein expression of nuclear factor kappa B, proinflammatory cytokines, namely tumor necrosis factor alpha and interleukin-1 β, as well as cyclooxygenase-2 and inducible nitric oxide synthase in the mice colon. Altered canonical Wnt signaling was confirmed by strong diaminobenzidine staining for p38 mitogen-activated protein kinase, b-catenin expression, and absence of adenomatous polyposis coli following B(a)P administration. Overall, our results show that exposure of mice to B(a)P induces colonic toxicity by mechanism involving oxidative and nitrosative stress, inflammation, and dsyregulation of Wnt/b-catenin signaling, and emphasizes the role of environmental polycyclic aromatic hydrocarbons like B(a)P in the pathology of colonic toxicity and tumorigenesis. Citation Format: Ebenezer O. Farombi, Babajide O. Ajayi, Isaac A. Adedara, Solomon E. Owumi. Induction of oxidative/nitrosative stress, proinflammatory cytokines and dysregulation of Wnt/beta-catenin signaling by benzo(a)pyrene in colons of BALB/c mice [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A40.

Meta-analysis of 16S rRNA Microbial Data Identified Distinctive and Predictive Microbiota Dysbiosis in Colorectal Carcinoma Adjacent Tissue.

As research focusing on the colorectal cancer fecal microbiome using shotgun sequencing continues, increasing evidence has supported correlations between colorectal carcinomas (CRCs) and fecal microbiome dysbiosis. However, large-scale on-site and off-site (surrounding adjacent) tissue microbiome characterization of CRC was underrepresented. Here, considering each taxon as a feature, we demonstrate a machine learning-based method to investigate tissue microbial differences among CRC, colorectal adenoma (CRA), and healthy control groups using 16S rRNA data sets retrieved from 15 studies. A total of 2,099 samples were included and analyzed in case-control comparisons. Multiple methods, including differential abundance analysis, random forest classification, cooccurrence network analysis, and Dirichlet multinomial mixture analysis, were conducted to investigate the microbial signatures. We showed that the dysbiosis of the off-site tissue of colonic cancer was distinctive and predictive. The AUCs (areas under the curve) were 80.7%, 96.0%, and 95.8% for CRC versus healthy control random forest models using stool, tissue, and adjacent tissue samples and 69.9%, 91.5%, and 89.5% for the corresponding CRA models, respectively. We also found that the microbiota ecologies of the surrounding adjacent tissues of CRC and CRA were similar to their on-site counterparts according to network analysis. Furthermore, based on the enterotyping of tissue samples, the cohort-specific microbial signature might be the crux in addressing classification generalization problems. Despite cohort heterogeneity, the dysbiosis of lesion-adjacent tissues might provide us with further perspectives in demonstrating the role of the microbiota in colorectal cancer tumorigenesis.IMPORTANCE Turbulent fecal and tissue microbiome dysbiosis of colorectal carcinoma and adenoma has been identified, and some taxa have been proven to be carcinogenic. However, the microbiomes of surrounding adjacent tissues of colonic cancerous tissues were seldom investigated uniformly on a large scale. Here, we characterize the microbiome signatures and dysbiosis of various colonic cancer sample groups. We found a high correlation between colorectal carcinoma adjacent tissue microbiomes and their on-site counterparts. We also discovered that the microbiome dysbiosis in adjacent tissues could discriminate colorectal carcinomas from healthy controls effectively. These results extend our knowledge on the microbial profile of colorectal cancer tissues and highlight microbiota dysbiosis in the surrounding tissues. They also suggest that microbial feature variations of cancerous lesion-adjacent tissues might help to reveal the microbial etiology of colonic cancer and could ultimately be applied for diagnostic and screening purposes.

Pharmacokinetic, Antiproliferative and Apoptotic Effects of Phenolic Acids in Human Colon Adenocarcinoma Cells Using In Vitro and In Silico Approaches.

Colon cancer is the second most common cause of cancer deaths in the USA and Europe. Despite aggressive therapies, many tumors are resistant to current treatment protocols and epidemiological data suggest that diet is a major factor in the etiology of colon cancer. This study aimed to evaluate the antioxidant activity and the influence of 3,4-dihydroxyphenylacetic (3,4-DHPAA), p-coumaric (p-CoA), vanillic (VA) and ferulic (FA) acids on cell viability, cell cycle progression, and rate of apoptosis in human colon adenocarcinoma cells (HT-29). The results showed that all compounds tested reduce cell viability in human colon cancer cells. 3,4-DHPAA promoted the highest effect antiproliferative with an increase in the percentage of cells in G0/G1 phase, accompanied by a reduction of cells in G2/M phase. Cell cycle analysis of VA and FA showed a decrease in the proportion of cells in G0/G1 phase (10.0 µM and 100.0 µM). p-CoA and FA acids increased the percentage of apoptotic cells and non-apoptotic cells. 3,4-DHPAA seems to be the substance with the greatest potential for in vivo studies, opening thus a series of perspectives on the use of these compounds in the prevention and treatment of colon cancer.

Is Colon Cancer a Consequence of Schistosomiasis: A Case Report

Colorectal cancer is one of the most common cancers worldwide with increasing prevalence in the Asian countries. Schistosoma japonicum, an endemic trematode in these countries, has been recognized as a colonic carcinogen. We report a case of resected rectal adenocarcinoma in a Filipino lady whose pathology was significant for Schistosoma eggs. A 69 year old Filipino lady with a history of resected left-sided invasive ductal carcinoma of breast presented with complaints of chronic lower abdominal discomfort, constipation alternating with diarrhea and weight loss for around 10 months. Physical examination and laboratory tests were noncontributory other than a normocytic anemia with hemoglobin of 11.6 gm/dl. Subsequent colonoscopy revealed a malignant appearing obstructive mass in the distal sigmoid colon (figure A). Magnetic resonance imaging showed bladder wall thickening with poor visualization of other structures due to limited oral contrast. An exploratory laparotomy successively resulted in anterior pelvic exenteration, sigmoid resection with primary anastomosis and ileal conduit creation for sigmoid cancer invading bladder. Her pathology demonstrated invasive moderately differentiated adenocarcinoma and numerous Schistosoma eggs in the colon, ovaries, posterior cul-de-sac and pelvic wall (Figure B). The parasitic infection was treated with praziquental and a stool microscopic examination in 3 weeks was negative for ova and parasites. Schistosomal infestation has been implicated by International Agency for Research on Cancer as an etiology for several cancers such as colon, liver and bladder. Schistosoma is known to trigger chronic inflammatory changes and epithelial hypertrophy, which sets foundation for dysplasia and consequent carcinoma. Production of genotoxic mediators such as reactive oxygen species and cytokines are proposed to play a role in dysregulation of oncogenes and oncogene suppressors. Our patient was from the Philippines, where prevalence rates of Schistosoma japonicum have been reported to be as high as 28%. It is likely to be the etiology of colon cancer in our patient. In Western countries, physicians should be aware of such associations when dealing with immigrants of endemic areas to facilitate early diagnosis and management. The causal relationship and benefit of screening and treatment for Schistosoma is a subject of debate and needs further research.1496_A Figure 1. Colonoscopy revealing a malignant appearing obstructive mass at the distal sigmoid colon1496_B Figure 2. Colonoscopy revealing a malignant appearing obstructive mass at the distal sigmoid colon1496_C Figure 3. Histopathology of resected sigmoid colon revealing Schistosoma eggs and moderately differentiated adenocarcinoma

Pulmonary Tumor Thrombotic Microangiopathy: A Rare Sequela of End-Stage Colon Cancer

This report aims to raise awareness of pulmonary tumor thrombotic microangiopathy (PTTM), a diagnosis made almost exclusively postmortem. The etiology of colon cancer has only been documented in a small number of articles. Furthermore, the distinctive morphological and behavioral features in this particular adenocarcinoma are compared and contrasted to those of other primary malignancies that have been previously described. A full autopsy including brain performed on a middle-aged man after sudden death revealed an undiagnosed colon cancer. Gross and microscopic findings demonstrated pulmonary tumor embolism with associated PTTM as the cause of death. During a hospital admission for neurological symptoms, a 60-year-old male became progressively hypotensive and developed acute shortness of breath. He subsequently developed cardiac arrest and expired shortly after. The major autopsy discovery was a moderate to poorly differentiated rectosigmoid colon adenocarcinoma with widespread metastasis. Extensive tumor emboli occluding small peripheral pulmonary blood vessels bilaterally were presumed to be the immediate cause of death. Cardiomegaly with pulmonary and hepatic congestion suggested cor pulmonale. Similar in presentation as venous thromboembolism, pulmonary tumor embolism should be included in the clinical differential diagnosis for cause of sudden death after progressive dyspnea especially in patients with malignancies. PTTM refers to the wall thickening of pulmonary arteries as a reactive change to tumor thrombi. Over time, pulmonary hypertension and consequent cor pulmonale follow. Morphologically, the poorly differentiated population of tumor cells in this report is comparable to the signet-ring cell carcinoma of the stomach and previously reported colonic adenocarcinomas of the same grade that is typically associated with PTTM. However, it was the population of moderately differentiated tumor cells of this case that metastasized and formed thrombi.

Montelukast, a CysLT1 receptor antagonist, reduces colon cancer stemness and tumor burden in a mouse xenograft model of human colon cancer

Inflammation is implicated in the etiology of sporadic colon cancer (CC), which is one of the leading causes of cancer-related deaths worldwide. Here, we report that inhibition of the inflammatory receptor CysLT1 through its antagonist, montelukast, is beneficial in minimizing stemness in CC and thereby minimizing tumor growth in a mouse xenograft model of human colon cancer. Upon treatment with montelukast, colonospheres derived from HT-29 and SW-480 human colon cancer cells exhibited a significant phenotypic change coupled with the downregulation of mRNA and protein expression of cancer stem cell (CSC) markers ALDH1 and DCLK1. Moreover, montelukast reduced the size of HT-29 cell-derived tumors in mice. The reduction in tumor size was associated with decreased levels of ALDH1A1, DCLK1, BCL2 mRNA and macrophage infiltration into the tumor tissue. Interestingly, this treatment elevated levels of the tumor suppressor 15-PGDH while reducing COX-2 expression. Our data highlight the association of CysLT1R with CSCs and demonstrate that inhibition of CysLT1R could prove beneficial in minimizing CSC-induced tumor growth. This work advances the notion that targeting CSCs is a promising approach to improve outcomes in those afflicted with colon cancer.

Chemopreventive effects of some popular phytochemicals on human colon cancer: a review.

Colon cancer is one of the major causes of morbidity and mortality worldwide. Dietary phytochemicals have been drawing increasing attention for colon cancer prevention and treatment due to their chemical diversity, biological activity, easy availability, lack of toxic effects, and ability to modulate various signal transduction pathways and cell processes. The chemoprotective effects elicited by phytochemicals include antioxidative and anti-inflammatory activities, induction of phase II enzymes, cell cycle arrest, apoptosis, autophagy, and changes in gut microbiota. The present review summarizes the main chemopreventive properties of selected phytochemicals (carotenoids, flavonoids, flavonolignan, proanthocyanidin, isothiocyanates, terpenoids, peptides, and medicinal plant extracts) against colon cancer. It is found that these phytochemicals exhibit their anti-colon cancer activity through the modulation of various signaling pathways involved in the regulation of chronic inflammation, cell cycle, autophagy, apoptosis, metastasis, and angiogenesis. These phytochemicals could be helpful starting points in the design and development of novel colon cancer chemopreventive agents.

Rectal Cancer in Asian vs. Western Countries: Why the Variation in Incidence?

Colorectal cancer (CRC) is the third most common cancer worldwide. CRC has been thought to be less common in Asia compared to Western countries. However, the incidence rates of CRC in Asia are high and there is an increasing trend in the Asian population. Furthermore, colorectal cancer accounts for the greatest number of all incidences of CRC in Asia. The increasing adoption of a Western lifestyle, particularly in dietary habits, is likely the most important factor contributing to the rapid increase in colon cancer incidence; it is noteworthy that trends for rectal cancer were flat. The etiology of colon and rectal cancer is a bit different. The risks of distal colon and rectal cancers are more likely to be related to environmental factors, such as polluted surface water sources, alcohol consumption, and habitual smoking. The lack of great change in the incidence of rectal cancer might be due to weaker associations with such lifestyle factors. Therefore, it has been hypothesized that proximal and distal sections of the colon and rectum are two different organs in terms of function and genetic background. It may mean differences in differential sensitivities and exposures to carcinogens. However, despite the decrease in whole incidence, the CRC incidence in young adults in Western countries are reversely increasing, especially in rectal cancer, due to reasons largely unknown. Although the treatment algorithm is different between Asia and western countries, globally, the survival rate for patients with rectal cancer has risen during the past 10years. Screening contributes a great deal to reducing the incidence and improving survival. Most countries in Asia, such as China, need nationwide registration and screening systems to provide better data.

Constitutively active RAS signaling reduces 1,25 dihydroxyvitamin D-mediated gene transcription in intestinal epithelial cells by reducing vitamin D receptor expression

High vitamin D status is associated with reduced colon cancer risk but these studies ignore the diversity in the molecular etiology of colon cancer. RAS activating mutations are common in colon cancer and they activate pro-proliferative signaling pathways. We examined the impact of RAS activating mutations on 1,25 dihydroxyvitamin D (1,25(OH)2D)-mediated gene expression in cultured colon and intestinal cell lines. Transient transfection of Caco-2 cells with a constitutively active mutant K-RAS (G12 V) significantly reduced 1,25(OH)2D-induced activity of both a human 25-hydroxyvitamin D, 24 hydroxyase (CYP24A1) promoter-luciferase and an artificial 3X vitamin D response element (VDRE) promoter-luciferase reporter gene. Young Adult Mouse Colon (YAMC) and Rat Intestinal Epithelial (RIE) cell lines with stable expression of mutant H-RAS had suppressed 1,25(OH)2D-mediated induction of CYP24A1 mRNA. The RAS effects were associated with lower Vitamin D receptor (VDR) mRNA and protein levels in YAMC and RIE cells and they could be partially reversed by VDR overexpression. RAS-mediated suppression of VDR levels was not due to either reduced VDR mRNA stability or increased VDR gene methylation. However, chromatin accessibility to the VDR gene at the proximal promoter (−300bp), an enhancer region at −6kb, and an enhancer region located in exon 3 was significantly reduced in RAS transformed YAMC cells (YAMC-RAS). These data show that constitutively active RAS signaling suppresses 1,25(OH)2D-mediated gene transcription in colon epithelial cells by reducing VDR gene transcription but the mechanism for this suppression is not yet known. These data suggest that cancers with RAS-activating mutations may be less responsive to vitamin D mediated treatment or chemoprevention.

Chemopreventive and Chemotherapeutic Effects of Fish Oil derived Omega-3 Polyunsaturated Fatty Acids on Colon Carcinogenesis.

Colorectal cancer is the third most common cause of cancer related death in the world. Multiple lines of evidence suggest that there is an association between consumption of dietary fat and colon cancer risk. Not only the amount but also the type and the ratio of fatty acids comprising dietary fats consumed have been implicated in the etiology and pathogenesis of colon cancer. Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have been known to inhibit development of colon cancer by downregulating the expression of genes involved in colon carcinogenesis and also by altering the membrane lipid composition. Data from laboratory, epidemiological, and clinical studies substantiate the beneficial role of n-3 PUFAs in preventing colitis and subsequent development of colon cancer. In addition, recent studies suggest that some n-3 PUFAs can be effective as an adjuvant with chemotherapeutic agents and other natural anticancer compounds in the management of colon cancer. In this review, we discuss chemopreventive and therapeutic effects of fish oil derived long chain n-3 PUFAs, particularly EPA and DHA, with focus on synergetic effects of which they exert when combined with chemotherapeutic agents and other natural compounds.

Does the Diversity of the Microbiome Reflect Possible Colonic Polyps in a Multi-ethnic Population?

Introduction: Colorectal cancer (CRC) is the third most common cause of malignancy-related death in the USA. The etiology of colon cancer is multifactorial; however, linkage to alterations in the gut microbiome has been reported. Hypotheses for oncogenesis include the induction of a chronic inflammatory state, cell cycle dysregulation and exposure to carcinogenic compounds, any of which might reflect a disordered microbiome. In this pilot study, we aimed to assess colonic and fecal microbiota with respect to presence of colonic polyps in a multiethnic population. Methods: Asymptomatic patients at average risk for CRC referred for screening colonoscopy were prospectively enrolled and consented. A detailed history was obtained via a standardized validated questionnaire. Stool was collected prior to (baseline, pre-preparation) and 3 weeks after colonoscopy. Biopsies were obtained from normal-appearing sigmoid mucosa in all subjects and normal-appearing mucosa within 5 cm of any polyp. DNA was purified from stool and tissue using standard extraction methods and bacterial sequencing and taxa identified using high throughput (Ilumina) 16S rRNA gene (V4 region) sequencing and analysis using the Qiime pipeline. Results: Demographics are presented in Table 1. In the 17 non-polyp controls, α and β diversity were similar in the pre-colonoscopy and the follow-up samples, 3 weeks later, indicating that the microbiota had normalized after the procedure. Analysis of gut microbiota showed lower α-diversity at baseline in subjects with polyps compared to controls, by the PD- whole-tree (p=0.014) metric. In the second sample, after polyp removal, α-diversity trended toward normalization but differences were not significant (p=0.6). Healthy colonic tissue showed higher α-diversity in subjects with adenomatous polyps compared with those with hyperplastic or no polyps (p=0.025). In subjects with polyps, α-diversity was higher in healthy tissue compared to tissue obtained within proximity of a polyp (p=0.02). There were no significant differences in β-diversity between subjects with or without polyps at any time.Table 1: Demographics and clinical features of 34 study subjectsConclusion: In our population, the lowered α-diversity (richness) prior to colonoscopy in the subjects with polyps and in tissue near a polyp suggests that the microbiota changes might be secondary to the neoplastic lesion. Larger studies are needed to question this finding in other multi-ethnic populations. Supported in part by 1R24OD01A340-01 from NIH.

Microbial transformation of contraceptive drug etonogestrel into new metabolites with Cunninghamella blakesleeana and Cunninghamella echinulata

Biotransformation of a steroidal contraceptive drug, etonogestrel (1), (13-ethyl-17β-hydroxy-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3-one) was investigated with Cunninghamella blakesleeana and C. echinulata. Five metabolites 2–6 were obtained on incubation of 1 with Cunninghamella blakesleeana, and three metabolites, 2, 4, and 6 were isolated from the transformation of 1 with C. echinulata. Among them, metabolites 2–4 were identified as new compounds. Their structures were deduced as 6β-hydroxy-11,22-epoxy-etonogestrel (2), 11,22-epoxy-etonogestrel (3), 10β-hydroxy-etonogestrel (4), 6β-hydroxy-etonogestrel (5), and 14α-hydroxy-etonogestrel (6). Compounds 1–6 were evaluated for various biological activities. Interestingly, compound 5 was found to be active against β-glucuronidase enzyme with IC50 value of 13.97±0.12μM, in comparison to standard compound, d-saccharic acid 1,4-lactone (IC50=45.75±2.16μM). Intestinal bacteria produce β-glucuronidase. Increased activity of β-glucuronidase is responsible for the hydrolyses of glucuronic acid conjugates of estrogen and other toxic substances in the colon, which plays a key role in the etiology of colon cancer. Inhibition of β-glucoronidase enzyme therefore has a therapeutic significance. Compounds 1–6 were also found to be non cytotoxic against 3T3 mouse fibroblast cell lines.