Form Of Colorectal Cancer Research Articles

Urolithin A affects cellular migration and modulates matrix metalloproteinase expression in colorectal cancer cells.

Colorectal cancer (CRC) is the world's second most common gastrointestinal malignancy. Preventing tumor cell proliferation and dissemination is critical for patient survival. Polyphenols have a variety of health advantages and can help prevent cancer. The current study examined different cellular activities of the gut-microbiota metabolite urolithin A (UA) on several colon cancer cell lines. The results revealed that UA suppressed cell growth in a dose- and time-dependent manner. In the current investigation, UA substantially affected cell migration in the wound-healing experiment and greatly decreased the number of colonies generated in each CRC cell culture. UA decreased cellular migration in CRC cells 48 h after treatment, which was significant (p < .001) compared to the migration rate in untreated cells. When compared to untreated cells, UA slowed the process of colony formation by reducing the number of colonies or altering their morphological shape. The western blot analysis investigation revealed that UA inhibits cellular metastasis by lowering the expression levels of matrix metalloproteinases 1 and 2 (MMP1 and MMP2) by more than 43% and 41% (p < .001) in HT29, 28% and 149% (p < .001) in SW480, and 90% and 74% (p < .001) in SW620, respectively, at a 100 µM dosage of UA compared to the control. Surprisingly, at a 100 µM dosage of UA, the expression levels of the tissue inhibitor of metalloproteinases 1 (TIMP1) were elevated in HT29, SW480, and SW620 cells treated with 100 µM of UA by more than 89%, 57%, and 29%, respectively. Our findings imply that UA has anticancer properties and might be used therapeutically to treat CRC. The findings provided the first indication of the influence of UA on cellular migration and metastasis in colon cancer cells. All of these data showed that UA might be used as an adjuvant therapy in the treatment of various forms of CRC.

Identification of diverticular disease in Swedish healthcare registers: a validation study

Purpose The Swedish National Patient Register (SNPR) is frequently used in studies of colonic diverticular disease (DD). Despite this, the validity of the coding for this specific disease in the register has not been studied. Methods From SNPR, 650 admissions were randomly identified encoded with ICD 10, K572-K579. From the years 2002 and 2010, 323 and 327 patients respectively were included in the validation study. Patients were excluded prior to, or up to 2 years after a diagnosis with IBD, Celiac disease, IBS, all forms of colorectal cancer (primary and secondary), and anal cancer. Medical records were collected and data on clinical findings with assessments, X-ray examinations, endoscopies and laboratory results were reviewed. The basis of coding was compared with internationally accepted definitions for colonic diverticular disease. Positive predictive values (PPV) were calculated. Results The overall PPV for all diagnoses and both years was 95% (95% CI: 93–96). The PPV for the year 2010 was slightly higher 98% (95% CI: 95–99) than in the year 2002, 91% (95% CI: (87–94) which may be due to the increasing use of computed tomography (CT). Conclusion The validity of DD in SNPR is high, making the SNPR a good source for population-based studies on DD.

Medullary thyroid cancer: a little history

The literature review presents the history on the development of modern ideas about medullary thyroid cancer, which is a little more than fifty years. It demonstrates the impressive achievements of modern science, which made it possible to move from clinical and morphological descriptions of individual cases and variants of diseases to studying and elucidating the mechanisms of their development at the molecular genetic level within a short period of time. To a large extent, this became possible thanks to the discovery of a number of combined forms of endocrine pathology, in particular multiple endocrine neoplasia syndromes among which medullary thyroid cancer plays a leading role. Based on achievements in this field, a method of surgical correction of medullary cancer even before its occurrence was proposed, which marked the emergence of a new direction in surgery— a preventive surgery. The history of studying medullary thyroid cancer begins with the discovery of a separate population of cells present in a small amount of thyroid tissue. In his report made at the meeting of the Royal College of Physicians in London on January 27, 1876, called Contribution to the minute anatomy of the thyroid of the dog, E. Cresswell Barber first described the presence of clusters of unusual cells in the gland, which morphologically differed from the known follicular cells. Currently, a new direction of clinical surgery is being formed— a preventive surgery. The basic principle of prophylactic surgery is the removal of one or another organ, if the absolute risk of developing a specific pathological process in it is proven. In the situation under consideration, this is medullary thyroid cancer, which occurs in 100% of individuals who are hereditary carriers of the mutant RET proto-oncogene. A similar risk exists for persons with some forms of colorectal cancer, malignant tumors of the mammary gland, ovaries in which their hereditary origin has been proven on the basis of detected mutations of certain genes. Intestinal resection, mastectomy, oophorectomy lead to the elimination of the potential threat of tumor development or its removal in situ, when it has not yet acquired the nature of a formed malignant neoplasm.

Abstract 2420: Exploring associations between the IL4 pathway and colorectal cancer risk in in vivo models and clinical records

Abstract We have previously demonstrated that inhibition of the IL4 pathway limits metastatic potential in colorectal cancers and have postulated that the type II IL4 receptor could serve as a potential target in risk assessment and treatment. Here we expand on these findings through in vivo mouse studies and retrospective patient analysis. To elucidate how colorectal cancers may use the IL4 pathway to grow and infiltrate surrounding tissue, we performed two in vivo studies independently targeting IL4ra in myeloid and intestinal epithelial tissues. Mice with a deleted allele of IL4ra and a floxed allele of IL4ra were crossed with either a line expressing a myeloid-specific Cre (LysM Cre) or an intestinal epithelial-specific Cre (Villin Cre). Our results indicate that myeloid-expressed IL4ra facilitates tumorigenesis but is not a significant contributor to later growth. In contrast, epithelial IL4ra significantly contributes to tumor number and size, but had little effect on the observed number of aberrant crypt foci, an early indicator of colon cancer. We hypothesized that effects of atypical IL4 activity could also be observed in the medical record. Atopic diseases such as asthma and eczema are characterized by an overabundance of IgE, a protein regulated by the IL4 pathway. Using Vanderbilt University Medical Center’s SD Discover program, we obtained de-identified records for patients diagnosed with at least stage II colorectal carcinoma between 2005 and 2015. We then stratified patients by metastatic progression. Patients who were diagnosed with asthma prior to age sixty were significantly less likely to develop an advanced form of colorectal cancer and at reduced risk of metastatic disease or recurrence. This may be a result of medication prescribed for atopic disease such as inhalers and corticosteroids and we are performing further analyses to test these hypotheses. Citation Format: Jacob Beckstead, Jack Petros, Kunaal Mehrotra, Barbara Fingleton. Exploring associations between the IL4 pathway and colorectal cancer risk in in vivo models and clinical records [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2420.

The structure of synchronous multiple primary colorectal cancer

One of the problems of modern oncology is the lack of timely diagnosis of synchronous forms of colorectal cancer. Therefore, the aim of this study was to evaluate the structure of synchronous primary multiple forms of colorectal cancer. Methods: We analyzed the results of colorectal cancer diagnostics (n = 583) in the period 2010–2019. We did not include patients with metachronous colorectal cancer in the study. The average age of all patients was 71.6 ± 7.4 years. There were 1.5 times more men than women. Results: Synchronous colorectal cancer was detected in 171 (29.3%) patients. With synchronous primary multiple forms of colorectal cancer, 2 tumors were diagnosed in every second patient. In synchronous colorectal cancer, tumors were localized twice as often in the colon (n = 118) than in the rectum (n = 53). Conclusions: In patients with colorectal cancer, synchronous tumors occur in every third case. Synchronous colorectal cancer is more common in men. In the majority of patients (59.1%), synchronous colorectal cancer was detected within 6 months after imaging of the primary tumor.

Casein Kinase-1-Alpha Inhibitor (D4476) Sensitizes Microsatellite Instable Colorectal Cancer Cells to 5-Fluorouracil via Authophagy Flux Inhibition

Adjuvant chemotherapy with 5-fluorouracil (5-FU) does not improve survival of patients suffering from a form of colorectal cancer (CRC) characterized by high level of microsatellite instability (MSI-H). Given the importance of autophagy and multi-drug-resistant (MDR) proteins in chemotherapy resistance, as well as the role of casein kinase 1-alpha (CK1α) in the regulation of autophagy, we tested the combined effect of 5-FU and CK1α inhibitor (D4476) on HCT116 cells as a model of MSI-H colorectal cancer. To achieve this goal, the gene expression of Beclin1 and MDR genes, ABCG2 and ABCC3 were analyzed using quantitative real-time polymerase chain reaction. We used immunoblotting to measure autophagy flux (LC3, p62) and flow cytometry to detect apoptosis. Our findings showed that combination treatment with 5-FU and D4476 inhibited autophagy flux. Moreover, 5-FU and D4476 combination therapy induced G2, S and G1 phase arrests and it depleted mRNA of both cell proliferation-related genes and MDR-related genes (ABCG2, cyclin D1 and c-myc). Hence, our data indicates that targeting of CK1α may increase the sensitivity of HCT116 cells to 5-FU. To our knowledge, this is the first description of sensitization of CRC cells to 5-FU chemotherapy by CK1α inhibitor.Graphic abstract

Abstract 2180: Somatic mutation landscape in early-onset colorectal cancer tumors from hispanics

Abstract Background: In the last 40 years, the incidence of colorectal cancer (CRC) among individuals &amp;lt;50 years (early-onset CRC) has been increasing at an alarming rate in the US, and is expected to increase by &amp;gt;140% by 2030. Early-onset CRC represents a clinically distinct form of CRC often associated with a poor prognosis. During 2012-2017, more than 11% of the CRC cases in the US and more than 9% of the total CRC cases in Puerto Rico corresponded to patients &amp;lt;50 years old. This highlights the imperative need to describe the genetic drivers of early-onset CRC in Hispanics in order to increase early diagnosis, improve personalized clinical management, and improve survival outcomes. The objective of this study was to characterize the somatic mutation profile of early-onset tumors from Puerto Ricans, a Hispanic subpopulation with a high CRC burden, in order to better understand early-onset CRC biology. Methods: Whole exome sequencing analyses were performed using the HiSeq4000 System (Illumina) on concordant colorectal adenocarcinoma and colonic mucosa tissue samples from 58 individuals diagnosed with colorectal cancer at &amp;lt;50 years old (early-onset CRC) and 25 individuals diagnosed with CRC &amp;gt;60 years old (late-onset CRC). Somatic variant calling and annotation/visualization were performed using Strelka and Ingenuity Variant Analysis software, respectively. All participants were recruited by Puerto Rico Familial Colorectal Cancer Registry (PURIFICAR). Results: Early-onset and late-onset CRC tumors showed distinct mutational profiles, only sharing TTN and MUC19 among their top 10 most mutated genes. The most frequently mutated genes in early-onset CRC tumors were: TTN (79%), MUC19 (75%), SYNE1 (68%), PCDHGA1 (68%), LPR1B (67%), PCDHGA2 (67%), PCDHGA3 (65%), PCDHGB1 (%), MUC16 (65%) and PCDHGA4 (65%). In late-onset CRC, the top ten most frequently mutated genes were: CSMD1 (68%), APC (68%), SYNE1 (64%), TTN (60%), MUC19 (60%), MUC16 (60%), PCDHA1 (60%), PCDHB1 (%), PCDHG1 (60%) and PCDHG2 (60%). Conclusion: This study presents the somatic mutation profile of early-onset colorectal tumors from Puerto Ricans, a Hispanic subgroup with noted CRC health disparities. Somatic mutational profiles were found to be distinct when comparing early-onset and late-onset colorectal tumors. The majority of the somatic mutations detected in the early-onset CRC tumors were in non-coding regions, suggesting that epigenetic regulation may contribute to early-onset colorectal carcinogenesis. Citation Format: Maria Gonzalez-Pons, Ingrid Montes-Rodriguez, Kelvin Carrasquillo-Carrion, Abiel Roche-Lima, Sandeep Singhal, Anna M. Napoles, Jung S. Byun, Eliseo Perez-Stable, Kevin Gardner, Marcia Cruz-Correa. Somatic mutation landscape in early-onset colorectal cancer tumors from hispanics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2180.

Identification and management of Lynch syndrome in the Middle East and North African countries: outcome of a survey in 12 countries

BackgroundLynch syndrome (LS), the most common inherited form of colorectal cancer (CRC), is responsible for 3% of all cases of CRC. LS is caused by a mismatch repair gene defect and is characterized by a high risk for CRC, endometrial cancer and several other cancers. Identification of LS is of utmost importance because colonoscopic surveillance substantially improves a patient’s prognosis. Recently, a network of physicians in Middle Eastern and North African (ME/NA) countries was established to improve the identification and management of LS families. The aim of the present survey was to evaluate current healthcare for families with LS in this region.MethodsA questionnaire was developed that addressed the following issues: availability of clinical management guidelines for LS; attention paid to family history of cancer; availability of genetic services for identification and diagnosis of LS; and assessment of knowledge of LS surveillance. Members of the network and authors of recent papers on LS from ME/NA and neighbouring countries were invited to participate in the survey and complete the online questionnaire.ResultsA total of 55 individuals were invited and 19 respondents from twelve countries including Algeria, Azerbaijan, Cyprus, Egypt, Iran, Jordan, Kuwait, Lebanon, Morocco, Palestine, Tunisia, and Turkey completed the questionnaire. The results showed that family history of CRC is considered in less than half of the surveyed countries. Guidelines for the management of LS are available in three out of twelve countries. The identification and selection of families for genetic testing were based on clinical criteria (Amsterdam criteria II or Revised Bethesda criteria) in most countries, and only one country performed universal screening. In most of the surveyed countries genetic services were available in few hospitals or only in a research setting. However, surveillance of LS families was offered in the majority of countries and most frequently consisted of regular colonoscopy.ConclusionThe identification and management of LS in ME/NA countries are suboptimal and as a result most LS families in the region remain undetected. Future efforts should focus on increasing awareness of LS amongst both the general population and doctors, and on the improvement of the infrastructure in these countries.

Hereditary Nonpolyposis Colorectal Cancer (HNPCC): From Diagnosis to Surgical Management of the Main Hereditary Form of Colorectal Cancer: A Review

Hereditary Nonpolyposis Colorectal Cancer (HNPCC): From Diagnosis to Surgical Management of the Main Hereditary Form of Colorectal Cancer: A Review

Hereditary Nonpolyposis Colorectal Cancer HNPCC: From Diagnosis to Surgical Management of the Main Hereditary Form of Colorectal Cancer: A Review

Colorectal cancer (CRC) is the third most common cancer worldwide, the 5% of CRC are hereditary. Among hereditary forms of CRC the most frequent is Hereditary Nonpolyposis Colorectal Cancer (HNPCC). HNPCC is an autosomal dominant genetic disease. Molecular basis of HNPCC are linked to genetic alterations, involving several mismatch repair (MMR) genes. Diagnosis of HNPCC is frequently difficult: HNPCC diagnosis process starts from family medical history and genetic counselling and continue with molecular diagnosis and genetic tests which often identify MMR genes mutation. In HNPCC the role of screening is irreplaceable for prevention and early diagnosis of CRC and extracolic cancer, such as endometrium, ovary, urothelium, stomach, small bowel, pancreas, brain, biliary ducts neoplasms. Surgical management of HNPCC is significantly different between colonic and rectal cancer. The main problem in surgical approach for HNPCC patients is related to the possibility of developing metachronous colorectal cancer. The choice is always between extensive and segmental resection. The aim of this study is to give some practical indications to surgeons for the management of HNPCC patients.

Comprehensive approach to choosing surgical tactics for locally advanced forms of colorectal cancer in patients of older age groups

The objective is to improve the results of treatment of locally advanced colorectal cancer in patients of older age groups due to the personalized approach to choosing surgical tactics with a comprehensive assessment of the functional operability and molecular biological properties of the tumor.Material and methods. A comparative evaluation of the results of surgical treatment of locally advanced colorectal cancer in patients of different age groups was conducted on representative clinical material. We studied the molecular profile of tumors, taking into account the age factor, and the clinical significance of specific markers in predicting the results of treatment.Results. The most significant indicators of functional operability of patients that must be considered when choosing a surgical tactic were identified. . The features of the immunophenotype of tumors, taking into account the age factor, were determined; and the prognostic significance of specific immunohistochemical indicators was estimated.Conclusion. The use of a personalized approach to choosing surgical tactics allows to achieve encouraging results of treatment in geriatric patients with locally advanced colorectal cancer.

A novel RAS internal tandem duplication involving the switch II domain disrupts GAP-binding and activates oncogenic signaling.

e15069 Background: Recent clinical guidelines for expansion of molecular testing of oncogenic RAS mutations in colorectal carcinoma have led to increased identification of mutations in this patient population. The clinical characteristics of NRAS-mutated colorectal carcinoma have not been well established because of the lower prevalence of these mutations (&lt; 6%) as compared to oncogenic KRAS mutations. Here, we report the discovery of a novel internal tandem duplication (ITD) mutation of NRAS, which disrupts the Switch II domain in an index case of a patient with widely disseminated colorectal cancer. Methods: Hotspot next generation sequencing of a brain metastasis using a clinical solid tumor panel identified this novel NRAS ITD and a TP53 missense mutation (p.P275F). Whole exome sequencing of the primary tumor and two metastatic lesions (lung and brain) was performed to identify other genetic factors potentially driving the disease. Results: The above approach confirmed that the NRAS ITD and TP53 mutation were conserved between the primary tumor and both metastatic tumors and identified an additional pathogenic mutation in CSMD1 (a tumor suppressor gene). No other clearly pathogenic driver mutations were identified. Structural biology and biochemical analyses demonstrated that the inserted 15 amino acids prevented binding to GAP protein, leading to sustained RAS activation and increased interaction with RAF to stimulate downstream MAPK activation. Conclusions: These genomic and biochemical studies indicate that a novel NRAS ITD was the primary driver mutation of this aggressive colorectal carcinoma. Identical or similar ITDs in NRAS and KRAS may also drive other forms of colorectal cancer and other aggressive malignancies and represent a new subset of RAS-driven drug-resistant cancers.

Gene mapping and molecular analysis of hereditarynon-polyposis colorectal cancer (Lynch Syndrome)using systems biological approaches.

Hereditary non-polyposis colorectal cancer (HNPCC) also known as Lynch Syndrome (LS), is a hereditary form of colorectal cancer (CRC). LSis caused by mutations in the mismatch repair (MMR) genes, mostly in MLH1, MSH2, MSH6 and PMS2. Identification of these gene mutations is essential to diagnose CRC, especially at a young age to increase the survival rate. Using open target platform, we have performed genetic association studies to analyze the different genes involved in the LS and to obtain target for disease evidence. We have also analyzed upstream regulators as target molecules in the data sets. We discovered that MLH1, MSH2, MSH6, PMS2, MLH3, EPCAM, TGFBR2, FBXO11 and PRSS58 were showing most association in LS. Our findings may further enhance the understanding of the hereditaryform of CRC.

PO-350 MiRNAs and their relation to biological pathways in left- and right-sided colorectal cancer

IntroductionMicroRNAs (miRNAs) are involved in the regulation of gene expression in colorectal cancer (CRC), which has specific biological pathways that are predominant in either left- or right-sided CRC. However, it is unclear how miRNAs are associated with biological pathways in these two forms of CRC. Our hypothesis is that a comprehensive understanding of the fundamental biological signalling pathways in the two sides of CRC may aid in developing a decisive step towards precision medicine. We aim to clarify specific biological pathway differences of differentially expressed miRNAs between left- and right-sided CRC.Material and methodsWe extracted total RNA from 24 of left- and right-sided CRC tumour samples from Finnish patients using the mirVanaTM miRNA Isolation Kit (Thermo Fisher Scientific) in the discovery cohort. Libraries for small RNA sequencing were prepared using TruSeq® Small RNA Library Prep Kit (Illumina) and run on Illumina MiSeq. Differentially up-regulated miRNAs were identified using DeSeq2. For validation purposes, we used the mature miRSeq dataset of 201 CRC samples from The Cancer Genome Atlas. We analysed biological pathways of site-specific miRNAs from the discovery and validation cohorts using the DIANA/mirPath tool.Results and discussionsWe found 17 and 15 differentially up-regulated miRNAs in left- and right-sided CRC, respectively, in the discovery cohort. The left miRNAs were involved in the mTor, Wnt, PI3K-Akt signalling pathways. These pathways are the predominant pathways in left-sided CRC. The Wnt signalling pathway was also significant (false discovery rate <0.05) in the left miRNAs from the validation cohort. In the discovery cohort, the right miRNAs were involved in the TGF-β signalling pathway. This pathway is dominant in right-sided CRC also in earlier reports. Alongside with the pathway findings, we found that the discovery and validation cohorts share six miRNAs. One of these (hsa-miR-196b-5p) was differentially up-regulated in left-sided CRC and the rest of them (hsa-miR-625–3 p, hsa-miR-155–5 p, hsa-miR-625–5 p, hsa-miR-31–5 p and hsa-miR-330–5 p) in right-sided CRC.ConclusionOur findings highlight that there are site-specific miRNAs in left and right-sided CRC. The results also indicate the involvement of these left and right miRNAs in different predominant biological pathways of the two forms of CRC. This exploration may be useful for further studies on the development of diagnosis in left- and right-sided CRC.

Palliative Primary Tumor Resection in Elderly and Senile Patients with Metastatic Colorectal Cancer

Late diagnosis of colorectal cancer (CRC), along with a high proportion of older patients, explain the relevance of studying the efficiency of cytoreductive surgery in geriatric patients with colorectal cancer. A comparative evaluation of the results of cytoreductive operations (removal of the primary tumor) in two groups of patients with disseminated CRC: younger and over 60 years old. It is established that the implementation of palliative resections in elderly and senile patients allows achieving encouraging long-term results, providing higher survival rates than in patients of young and middle age. More frequent development of complications after cytoreductive operations in patients of older age groups is usually associated with decompensation of the concomitant pathology, which requires its adequate correction in the preoperative period. The use of cytoreductive surgery in patients of older age groups with advanced forms of CRC significantly improves their quality of life.

Next Generation Sequencing in Molecular Diagnosis of Lynch Syndrome - a Pilot Study Using New Stratification Criteria.

The development of the new technologies such as the next-generation sequencing (NGS) makes more accessible the diagnosis of genetically heterogeneous diseases such as Lynch syndrome (LS). LS is one of the most common hereditary form of colorectal cancer. This autosomal dominant inherited disorder is caused by deleterious germline mutations in one of the mismatch repair (MMR) genes - MLH1, MSH2, MSH6 or PMS2, or the deletion in the EPCAM gene. These mutations eventually result in microsatellite instability (MSI), which can be easily tested in tumor tissue. According to the actual recommendations, all patients with CRC that are suspect to have LS, should be offered the MSI testing. When the MSI is positive, these patients should be recommended to genetic counseling. Here we report a pilot study about the application of NGS in the LS diagnosis in patients considered to have sporadic colorectal cancer. The inclusion criteria for the NGS testing were MSI positivity, BRAF V600E and MHL1 methylation negativity. We have used 5 gene amplicon based massive parallel sequencing on MiSeq platform. In one patient, we have identified a new pathogenic mutation in the exon 4 of the MSH6 gene that was previously not described in ClinVar, Human Gene Mutation Database, Ensembl and InSight databases. This mutation was confirmed by the Sanger method. We have shown that the implementation of new criteria for colorectal patients screening are important in clinical praxis and the NGS gene panel testing is suitable for routine laboratory settings.

Abstract A31: Targeting APC loss using synthetic lethality in Colorectal Cancer

Abstract Background: Mutations in the tumor suppressor gene Adenomatous Polyposis Coli (APC) are found in 80% of sporadic colorectal cancer (CRC) tumors and are also responsible for the inherited form of CRC, Familial Adenomatous Polyposis (FAP). APC mutations typically occur early in the development of CRC, followed by mutations in KRAS, SMAD2/3/4 and TP53. The majority of mutations in APC occur in a region known as the mutation cluster region (MCR). This region is responsible for negatively regulating levels of B-catenin and therefore the level of Wnt signaling activation. In APC mutated tumors, B-catenin is not tightly regulated resulting in hyperactivation of the Wnt signaling pathway leading to uncontrolled cellular proliferation, differentiation, migration and apoptosis. Aim: We aim to use the concept of synthetic lethality to identify novel therapeutic targets for the treatment of APC mutated CRC. Results: In order to identify novel therapeutic targets for the treatment of APC mutated CRC, we have generated an in vitro model of APC mutant CRC using a lentiviral CRISPR-cas9 system. Using the APC wildtype colorectal carcinoma cell line RKO, we targeted the cells with a guide RNA targeting the start of the final exon of APC, which covers 80% of the coding region. These cell lines allow us to identify targets, which are synthetically lethal with the APC mutation. To identify novel potential drug targets, we have used two parallel screening approaches. Firstly, we have screened our cell lines with a library of siRNA silencing over 700 kinases. Typically kinases are easy to target pharmaceutically, with many kinase inhibitors already clinically available. Upon analysis, we have identified seven genes which show synthetic lethality with the APC mutation, whilst not harming the control wildtype APC cells. In parallel, we have screened over 1000 FDA-approved compounds to identify drugs which cause increased selective lethality in APC mutant cells. From screening our FDA-approved compounds, we have identified a number of compounds which display synthetic lethality with the APC mutation. Conclusions: We have identified seven genes as potential therapeutic targets and a number of FDA-approved compounds, which could potentially be new selective therapies for 80% of CRC patients. Currently we are validating these findings and investigating the mechanism of synthetic lethality with APC mutation. To further validate our findings we are also exploring whether these results extend to other CRC cell lines with different mutational backgrounds, this will help us access how many patients may benefit from our novel therapeutic targets. Acknowledgments: We would like to thank Bowel and Cancer Research and The Rosetree Trust for co-funding this project. Citation Format: Hannah Shailes, Gemma Bridge, Daniel Foxler, Tyson V. Sharp, Andrew Silver, Sarah A. Martin. Targeting APC loss using synthetic lethality in Colorectal Cancer [abstract]. In: Proceedings of the AACR Precision Medicine Series: Opportunities and Challenges of Exploiting Synthetic Lethality in Cancer; Jan 4-7, 2017; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2017;16(10 Suppl):Abstract nr A31.

A novel heterozygous germline deletion in MSH2 gene in a five generation Chinese family with Lynch syndrome.

Lynch syndrome (LS) is one of the most common familial forms of colorectal cancer predisposing syndrome with an autosomal dominant mode of inheritance. LS is caused by the germline mutations in DNA mismatch repair (MMR) genes including MSH2, MLH1, MSH6 and PMS2. Clinically, LS is characterized by high incidence of early-onset colorectal cancer as well as endometrial, small intestinal and urinary tract cancers, usually occur in the third to fourth decade of the life. Here we describe a five generation Chinese family with LS clinically diagnosed according to the Amsterdam II criteria. Immuno-histochemical staining of MSH2 and MSH6 shows only foci nuclear positive on the surface of the tumor with strong expression of MLH1 and PMS2 with diffuse immunoreactivity. In order to dig into the molecular basis of this LS pedigree, we collected the proband's blood sample, extracted the genomic DNA and applied the genetic screening. As a result, we identified a novel heterozygous deletion in MSH2 gene by targeted next generation sequencing, which is also proved to be co-segregated among other affected family members by following validation. To our knowledge, this novel heterozygous deletion (c.1676_1679 delTAAA) in MSH2 gene causes frameshift mutation (p.Asn560Lysfs*29) and leads to the formation of a truncated MSH2 protein which is confirmed to be a deleterious mutation according to the variant interpretation guidelines of American College of Medical Genetics and Genomics (ACMG). Identification of novel DNA mismatch repair (MMR) gene mutations can definitely benefit to the clinical diagnosis and management.

Abstract 3400: Progression of epidermal growth factor receptor (EGFR)-independent colorectal cancer

Abstract When combined with standard of care treatment for colorectal cancer (CRC), the use of monoclonal antibodies or small molecule inhibitors against epidermal growth factor receptor (EGFR) show modest efficacy in the clinic. Early detection efforts and more effective therapies have reduced mortality, yet CRC remains the second mostly deadly cancer in the United States with approximately 50,000 deaths expected this year. Thus, it is imperative to better understand the mechanisms governing molecular progression of CRC. Primary and secondary resistance to anti-EGFR therapies occurs in approximately 80% of the patients with CRC. Mutations in Kras explain some non-responding CRCs, but even in cancers lacking Kras mutations, little is known about which cancers are likely to respond to EGFR targeted treatment, suggesting an alternative and EGFR-independent CRC progression mechanism. In this study, we used a conditional Egfr allele (Egfrf) within the ApcMin/+ mouse model and identified EGFR-independent tumors with faster growth rates than those developing in EGFR-wild type mice. To assess aggressiveness of EGFR-independent tumors, we used a metastatic CRC mouse model containing conditionally inactivated Apc alleles (Apcf/f) in combination with a conditionally active allele of Kras (KrasLSL-G12D). It has been reported that delivery of Cre recombinase-expressing adenovirus to the distal colon of these mice results in tumors that progress to carcinoma within 20 weeks, and liver metastases develop in approximately 20% of mice at 24 weeks. We discovered a 10% increase in the penetrance of tumors arising in the absence of EGFR (Egfrf/f, Apcf/f, KrasLSL-G12D/+). Endoscopic analysis suggests an increase in tumor multiplicity in EGFR-deficient tumors when compared with tumors developing in EGFR-wild-type mice. Biweekly colonoscopies confirmed that colonic tumors have a faster growth rate in the absence of EGFR. High-frequency abdominal ultrasound suggests liver metastasis at 16 weeks in 20% of mice lacking EGFR. These findings demonstrate the existence of an EGFR-independent mechanism by which CRC can arise and progress. Moreover, tumors lacking EGFR grow larger than those developing under normal EGFR activity and may be a more aggressive form of CRC. We also have evidence that ERBB3 and ERBB4, related EGFRs, mediate compensatory and alternative pathways, suggesting an important role for these receptors in the progression of EGFR-independent CRC. This study will advance our understanding of ERBB family biology during colonic tumorigenesis, ultimately contributing to better therapies for CRC. Citation Format: Carolina Mantilla Rojas, Yu Ming, David Threadgill. Progression of epidermal growth factor receptor (EGFR)-independent colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3400. doi:10.1158/1538-7445.AM2017-3400

Clostridium butyricum partially regulates the development of colitis-associated cancer through miR-200c.

Colitis-associated cancer (CAC), one form of colorectal cancer (CRC),is an increasing concern worldwide. Both diagnosis and current therapy are challenging and bottlenecked. The aim of this study is to investigate novel mechanisms by which the therapeutic C. butyricum regulates colitis-induced oncogenesis. Mouse models of CAC were established with 2,4,6-Trinitrobenzenesulfonic acid (TNBS)and azoxymethane (AOM), following by biochemical, clinical and histological analysis. The integrity of epitheliumwas examined by electron microscopy (EM). The epithelial barrier function was evaluated with Ussing chamber. Real time PCR and fluorescent in situ hybridization (FISH) were performed to characterize the effect of C. butyricum on miR-200c; cell proliferation assays (MTT) were performed to study the role ofC. butyricum on epithelial cell proliferation mediated by miR-200c inhibitor; finally, we quantified the proinflammatory cytokines TNF-α and interleukin (IL)-12 by real time PCR. C. butyricum ameliorates clinical, histological and biochemical manifestations in colitis-induced CAC models. Further mechanistic studies demonstrated that C. Butyricum could lengthen epithelial microvillus and increase TER by decreasing the transepithelial permeability. We also showed that C. butyricum facilitates the expression of miR-200c, by which increase the proliferation rate. Finally, we found that C. butyricum can regulate the production of proinflammatory cytokines TNF-α and IL-12 through miR-200c. C. butyricum may regulate epithelial barrier function through miR-200c, then to be involved in the process of inflammation-associated cancers.