Probiotics are viable nonpathogenic microbes that positively affect host health. Probiotics inhibit infection, activate immunity, and promote mucosal-barrier development. Many microbes have probiotic activity. Nonetheless, the selection of stable strains and their specific mechanism(s) of action are not fully elucidated. Bacteria from ‘Amabere amaruranu’ cultured milk from Kenya were isolated and identified by PCR sequence analysis of the 16S rRNA gene. Isolates were examined for stability to acid and bile, antimicrobial activity, mucin production, and degradation and sensitivity to antibiotics, hence their potential for probiotics. Lactobacillus isolates were acid unstable, bile-stable, nonmucinolytic, and presented antibacterial activity. L. rhamnosus cell fractions increased MUC4 and MUC3 expression in colon cells. Bacillus isolates were acid and bile stable, nonmucinolytic and lacked antimicrobial activity. In conclusion, Lactobacillus isolates that were nonmucinolytic, stable in bile, demonstrated antibacterial activity, sensitive to antibiotics, and stimulated increase MUC4 and MUC3 levels in colon cells could be potential probiotics.

Mucins, synthesised and secreted by goblet cells, possess potential binding sites for both commensal and pathogenic organisms, and may perform a defensive role during establishment of the intestinal barrier in newly hatched chickens. Increasing interest has been directed toward bacterial interactions within the mucus layer, and the mechanisms by which bacterial colonisation can influence mucus composition during early development. This is important, firstly, as a means to understand initiation of infection and secondly, to optimise the gut microflora for enhanced animal production. Currently, information on mucosal-bacterial interactions in poultry is limited. In order to observe the effects of bacterial exposure on intestinal goblet cell mucin production during early development, differences in the small intestine of conventionally-raised (CV) and low bacterial load (LBL) broiler chicks were examined during the first 7 days post-hatch. The initial aim of the study was to construct a small-scale, economical isolator system to hatch and raise chicks in a bacterial-free environment as a means to observe bacterial interactions with the intestinal mucosa in chickens exposed to normal environmental conditions. The design and construction of flexible plastic isolators for incubation and brooding are described, along with methodologies for preparation of eggs for entry into the isolators, incubation and hatching. Two trials were conducted, the first in August 2005 and the second in March 2006. It was found that the isolator system was successful in producing low bacterial load chicks for comparative studies with conventionally raised chicks, without compromising body weight. A histological study was then conducted whereby ileal and jejunal goblet cells were stained with either periodic acid-Schiff or high iron diamine/alcian blue pH 2.5 to discriminate between neutral, sulphated and sialyated acidic mucins. Total goblet cell numbers and goblet cell and villous/crypt morphology were also examined. Bacterial colonisation of CV animals induced an increase in sialic acid moieties in both ileal and jejunal goblet cell such that initiation of these changes occurred at day 3-4 post-hatch. Differences in intestinal morphology were also consistent with other germ-free animal studies. In order to further understand the extent to which bacteria affected mucin composition, purified, isolated oligosaccharide fractions from ileal mucin at d 4 and 7 post-hatch were collected and analysed using mass spectrometry techniques to determine any structural differences in chain length or chain number between LBL and CV animals. No differences in chain length or number were observed between CV and LBL animals at either d 4 or 7 post-hatch with both groups equally displaying chain lengths of both low and high molecular weights. Although structural differences in mucin oligosaccharides were not observed between LBL and CV animals, bacterial binding assays utilising whole ileal sections were employed to determine whether or not the differences in mucin composition between LBL and CV animals during early development may have deterred or enhanced binding of certain bacterial species. Escherichia coli and Lactobacillus salivarius were selected for the experiment. Binding of L. salivarius to ileal sections was very low whereas E. coli binding was greater, and more pronounced in LBL animals, especially at d 7 post-hatch. No statistically significant differences were observed in binding of E. coli to purified ileal mucin from LBL and CV animals at either d 4 or d 7 post-hatch. Correlations between E. coli and L. salivarius adherence to ileal tissue and mucin samples, and goblet cell parameters, were not statistically significant when fitted as co-variates. It was concluded that the changes in mucin composition played a minor role in bacterial adhesion of L. salivarius and this E. coli serotype. In summary, this thesis explores the physiological changes in goblet cell mucin production in response to bacterial exposure post-hatch. The thesis outlines the complexity of mucosal-bacterial interactions which would benefit from the employment of specialised techniques such as nuclear magnetic resonance spectroscopy and microarray technologies to examine a greater range of mucin structures and gene expression. This thesis provides support for future investigations into the influence of intestinal microflora on mucosal and mucin dynamics of poultry and the potential development of prebiotics for use in animal production. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297640 / Thesis (Ph.D.) -- School of Agriculture, Food and Wine, 2007

Nucleic Acid Sequence Based Amplification (NASBA) is a powerful in vitro technique for amplification. NASBA is routinely used in many fields of microbiology, including food microbiology, and most recently in the identification of forensic body secretions (saliva, tears, sweat, semen, vaginal secretions). NASBA has many advantages over the traditional Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) including speed, high sample throughput and increased sensitivity. Proper selection of the sequence of importance and the designe of NASBA primers precisely for that sequence are the two most critical steps for any NASBA assay. Proper designe of NASBA primers includes important considerations such as product (amplicon) length, the addition of a T7 RNA polymerase promoter sequence at the 5’end of one primer, and a 3’AT rich region. Primer designing is, therefore, laborious and error-prone. Currently, no such software is available that facilitates primer designing for NASBA. In this study Java-based software for designing NASBA primers was developed which will enable rapid and specific NASBA primer designing for gene expression studies. The designed program focused on scripting minimum Java coding lines to reduce the time and storage space. Two codes were scripted for this software, a pseudo-code (for Java Program Developers) and Byte-code (for Windows operating system). Our results showed that Java is an efficient tool in searching sequences of interest within a gene (or mRNA), allowing for NASBA primers to be designed more quickly and effortlessly. The program has maximum memory storage capacity and allows the users to retrieve old data with reference to date or time. To test the practicality of the newly developed program, gene sequences of salivary mucin and amylase were examined to facilitate extraction of novel RNA tandem repeat element NASBA markers for human saliva forensic identification. Tandem repeats of non-coding portion with in the of human genome are highly polymorphic and considered best for forensic use. Currently, only 13 Short Tandem Repeat (STR) markers are available for forensic case work, which are not enough to establish a definitive link between the victim and suspects. Identification and validation of a new human body fluid tandem repeat markers is cruicial for achieving high through put results and to exonerate the innocent. / Access to thesis permanently restricted to Ball State community only / Department of Biology

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 131-132). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 131-132). Also available on the Internet.

Thesis (Ph. D.)--University of Oklahoma. / Bibliography: leaves 116-150.

L’adénocarcinome pancréatique canalaire s’accompagne d’une néoexpression de la mucine membranaire MUC4 et d’une surexpression des mucines membranaires MUC1 et MUC16. Ces O-glycoprotéines de haut poids moléculaire sont codées par des ARNm possédant des particularités inhabituelles par rapport aux autres transcrits humains, comme une longue demi-vie et une très grande taille. La galectine-3, une lectine endogène également surexprimée au cours du cancer pancréatique, exerce de très nombreuses fonctions biologiques, en particulier dans le domaine du trafic intracellulaire des glycoprotéines et de l’épissage des pré-ARNm. Cependant, l’implication de cette galectine à un autre niveau du cycle de vie des ARNm n’avait pas été explorée jusque-là dans la littérature. De précédents travaux du laboratoire ont démontré que la suppression de l’expression de la galectine-3 dans la lignée cellulaire cancéreuse pancréatique humaine CAPAN-1 s’accompagne d’une diminution de l’expression des transcrits de certaines mucines membranaires. L’objectif de ce travail a donc été d’étudier les mécanismes de régulation de l’expression des mucines membranaires, et plus particulièrement MUC4, par la galectine-3.Nous avons démontré que la galectine-3, in vitro, régule l’expression de MUC4 au niveau post-transcriptionnel en stabilisant les transcrits de cette mucine. Ceci passe par la potentialisation de la fixation de la RNA Binding Protein hnRNP-L sur l’élément cis-régulateur CA repeat présent dans le 3’UTR de MUC4. Nos résultats indiquent que cette régulation est présente in vivo au niveau physiologique dans des tissus épithéliaux digestifs murins. Par ailleurs, nous avons mis en évidence que la galectine-3 interagit avec hnRNP-L dans le cytoplasme mais qu’elle interagit faiblement avec des marqueurs de P-Bodies ou de granules de stress. Concernant le rôle de la galectine-3 dans le cycle de vie des ARNm, nos données révèlent que celle-ci se lie à aux transcrits matures de MUC4 au niveau périnucléaire, probablement dans des granules de stockage qui ne sont ni des granules de stress ni des P-bodies et dont le type reste à déterminer. Nous avons également élargi nos résultats en étudiant l’implication de cette lectine dans le métabolisme d’autres ARNm et nos analyses indiquent que la galectine-3 serait impliquée dans la régulation post-transcriptionnelle positive ou négative d’un ensemble de transcrits dont les fonctions convergent vers les voies UPR (Unfolded protein response) et ERAD (Endoplasmic-reticulum-associated protein degradation) mais également plus généralement vers le processing des protéines en réponse au stress du réticulum endoplasmique.En conclusion, nos travaux mettent en évidence un nouveau rôle de la galectine-3 en tant que RNA binding protein dans la stabilisation des ARNm de MUC4 mais aussi un nouveau rôle dans la coordination de l’expression de répertoires de transcrits matures ayant des rôles biologiques communs (RNA regulon) permettant à la cellule de s’adapter au plan morphologique, métabolique et biologique à des changements physiopathologiques. Ceci renforce les interconnexions largement décrites dans la littérature entre mucines, galectine-3 et les grandes fonctions cellulaires qui sont perturbées en situation cancéreuse. / Pancreatic ductal adenocarcinoma is characterized by a neo expression of the membrane-bound mucin MUC4 and an overexpression of membrane-bound mucins MUC1 and MUC16. These high molecular weight O-glycoproteins are encoded by mRNA sharing unusual features among human transcripts, such as a long half-life and a very large size. Galectin-3, an endogenous lectin frequently over-expressed in pancreatic cancer, has many biological functions, especially in intracellular glycoprotein trafficking and pre-mRNA splicing. However, the involvement of this lectin in another step of mRNA life cycle has not been explored in literature yet. Previous works performed in the laboratory have demonstrated that LGALS3 gene knock-down in a human cancerous pancreatic cancer cell line is followed by a decrease of the expression of several membrane-bound mucin mRNAs. The aim of this present work was to study the mechanism of the regulation of mucins expression, especially for MUC4, by galectin-3.We have demonstrated that galectin-3, in vitro, regulates MUC4 expression at the post-transcriptionnal level through the stabilization of the transcripts of this mucin. Galectin-3 potentiates the binding of hnRNP-L, a RNA-Binding protein, on the CA repeat region present in MUC4 3’UTR. Our results show that this regulation occurs physiologically in vivo in mice digestive epithelial tissues. Moreover, we have demonstrated that galectin-3 interacts with hnRNP-L in cell cytoplasm but scarcely with protein markers of P-Bodies or stress granules markers. Regarding the influence of galectin-3 in mRNA life cycle, our results suggest that it binds to mature MUC4 transcripts in the perinuclear area, probably in storage granules whose type should to be determined. We have also broadened our results by studying this lectin’s involvement in the metabolism of other mRNA. Our analyzes suggest that galectin-3 could be involved in the positive or negative post-transcriptionnal regulation of a mRNA subset whose functions are linked to unfolded protein response (UPR) and Endoplasmic-reticulum-associated protein degradation (ERAD) pathways, but also more generally towards protein processing in response to endoplasmic reticulum stress.In conclusion, our work highlights a new function for galectin-3 as a RNA binding protein in the stabilization of MUC4 mRNA, but also a new function in the coordination of the expression of repertories of mature transcripts with shared functions or (RNA regulon) allowing morphological, biological and metabolic cell adaptation to physiopathological changes. These results strengthen the interplay between mucins, galectin-3 and cellular functions which are disturbed in cancer.

Abstract Pulmonary adenocarcinoma is the most common and most heterogeneous form of lung cancer, and its histological and biological diversity is well recognized. On its publication in 2011, the IASLC/ATS/ERS lung adenocarcinoma classification drew attention to the prognostic value of adenocarcinoma subtypes, and it has been anticipated to provide a novel architecture based grading system. The prognostic role of other tumor-associated features in lung adenocarcinoma is less established. MUC1 overexpression has been demonstrated in many carcinomas, and in lung adenocarcinoma, depolarized MUC1 expression has been associated with poor outcome. The role of MUC4 in lung cancer, however, is somewhat conflicting. Moreover, there is no published data on either MUC1 or MUC4 expression with regard to the different subtypes of lung adenocarcinoma. This study aimed to investigate the correlation between the IASLC/ATS/ERS classification, prognosis, and clinical characteristics in a series of 112 surgically resected lung adenocarcinoma patients. The analysis of tumor architecture aimed also at the discovery of new morphological biomarkers for lung cancer. Additionally, the study focused on the expression of MUC1, MUC4, and EGFR in lung adenocarcinoma, evaluating their relationship with tumor architecture, patient outcome, and smoking. The study applied the methods of light microscopy, immunohistochemistry, and cell culture with experimental cigarette smoke exposure combined with real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and immunoelectron microscopy. The study demonstrated that the prognostic value of the current adenocarcinoma classification is not limited to predominant growth patterns as a more favorable clinical outcome was associated with minor lepidic pattern. Significant associations were observed between adenocarcinoma subtypes and smoking history. Classic histological features of malignancy correlated with tumor architecture and survival, further confirming the prognostic value of semiquantitative growth pattern analysis and identifying potential prognostic biomarkers such as mitotic activity and tumor necrosis. Depolarized MUC1 expression correlated with histology and patient outcome, and moreover, with smoking both in vivo and in vitro, suggesting a pathogenetic relationship between cigarette smoke exposure and MUC1 in lung adenocarcinoma. / Tiivistelmä Keuhkon adenokarsinooma on maailmanlaajuisesti yleisin ja monella tapaa monimuotoisin keuhkosyöpätyyppi. Vuonna 2011 uusi kansainvälinen keuhkosyöpäluokitus nosti esille adenokarsinooman histologisten alatyyppien ennustemerkityksen, ja luokituksen on odotettu muodostavan pohjan uudelle kasvutapoihin perustuvalle gradeerausmenetelmälle. Kasvaimen muiden histopatologisten piirteiden ennusteellinen merkitys keuhkon adenokarsinoomassa on vähemmän tunnettu. MUC1-proteiinin yli-ilmentymistä on kuvattu monissa karsinoomatyypeissä, ja keuhkon adenokarsinoomassa MUC1:n poikkeava eli depolarisoitunut ilmentyminen on liitetty huonoon ennusteeseen. MUC4:n merkitys keuhkosyövässä on puolestaan ristiriitainen. Toisaalta MUC1- tai MUC4-ilmentymistä ei ole tutkittu tarkemmin keuhkon adenokarsinooman eri alatyypeissä. Väitöskirjatutkimuksessa pyrittiin selvittämään uuden adenokarsinoomaluokituksen yhteyttä ennusteeseen ja muihin kliinisiin muuttujiin aineistossa, joka käsitti 112 Oulun yliopistosairaalassa leikkaushoidettua keuhkon adenokarsinoomapotilasta. Kasvainten histopatologisten ominaispiirteiden kartoittamisen toivottiin tuovan ilmi myös uusia morfologisia ennustetekijöitä. Lisäksi tutkimus keskittyi MUC1-, MUC4- ja EGFR-proteiinien ilmentymiseen keuhkon adenokarsinoomassa, arvioiden niiden suhdetta kasvaimen histologiaan, potilaiden ennusteeseen ja tupakointihistoriaan. Tutkimusmenetelminä käytettiin valomikroskopiaa, immunohistokemiaa sekä kokeellista tupakka-altistusta soluviljelymallissa yhdistettynä kvantitatiiviseen reaaliaikaiseen käänteistranskriptiopolymeraasiketjureaktio-tekniikkaan (RT-qPCR) ja immunoelektronimikroskopiaan. Tutkimus osoitti, ettei nykyisen adenokarsinoomaluokituksen ennustearvo rajoitu hallitseviin kasvutapoihin, vaan myös väistyvä lepidinen kasvutapa vaikutti ennusteeseen suotuisasti. Keuhkon adenokarsinooman alatyyppien ja tupakoinnin välillä todettiin merkittävä yhteys. Pahanlaatuisten kasvainten klassiset histologiset piirteet liittyivät adenokarsinooman kasvutapoihin ja ennusteeseen korostaen semikvantitatiivisen kasvutapa-analyysin ennustemerkitystä ja tarjoten myös mahdollisia uusia ennustetekijöitä. Depolarisoituneen MUC1:n ilmentyminen liittyi histologiaan, ennusteeseen ja erityisesti tupakka-altistukseen sekä in vivo että in vitro. Tämä löydös viittaa mahdolliseen patogeneettiseen yhteyteen tupakoinnin ja MUC1:n välillä.

Les adénocarcinomes lépidiques prédominant (ALP) sont une entité originale sur le plan histologique, clinique et biologique parmi les adénocarcinomes pulmonaires. Il s’agit de tumeurs non-mucineuses mais il existe un variant mucineux, l’adénocarcinome mucineux invasif (AMI), caractérisé par un plus mauvais pronostic et l’absence de traitement efficace dans les formes avancées. L’objectif de ce travail était d’étudier les différences moléculaires distinguant ALP et AMI et d’en dégager les implications biologiques. Après avoir détaillé les caractéristiques cliniques et les altérations oncogéniques d’une cohorte d’ALP et d’AMI, nous avons exploité les banques de prélèvements issus de cette cohorte. Une étude de l’expression en immunohistochimie des mucines MUC1, 2, 5B, 5AC et 6 au sein des pièces opératoires de 27 ALP et 27 AMI montrait un profil d’expression spécifique entre ALP et AMI. L’expression de MUC1 était associée aux ALP, celle de MUC5AC, 5B et 6 aux AMI. L’expression de MUC1 était associée aux mutations EGFR et MUC5B et 5AC aux mutations KRAS. Un réarrangement NRG1 a été détecté par FISH dans 1 AMI sur 25. La chimiokine CXCL10 était surexprimée dans les surnageants de lavages broncho-alvéolaires (LBA) de patients avec AMI (n=38) comparés aux ALP (n=25), et cette surexpression était de mauvais pronostic. La voie cytokine/récepteur CXCL10/CXCR3-A était surexprimée dans les AMI, faisait la promotion de la migration des cellules tumorales mucineuses et gouvernait l’expression tumorale de VEGF. Le VEGF issu du LBA des patients était à l’origine in vitro d’une augmentation significative de la formation de tubes vasculaires inhibée par l’anti-VEGF bevacizumab. Le ciblage de CXCL10/CXCR3-A et du VEGF pourraient être des options thérapeutiques dans les AMI. Ces résultats permettent d’affiner les connaissances biologiques des ALP et des AMI et dégagent des voies de recherche originales qui pourraient amener au développement de nouveaux traitements / Lepidic predominant adenocarcinoma (LPA) represents an original entity in terms of histological, clinical and biological characteristics among adenocarcinomas of the lung. While LPA is typically a non-mucinous adenocarcinoma, a mucinous variant does exist, termed invasive mucinous adenocarcinoma (IMA), associated with a worse prognosis and a lack of effective treatment in advanced diseases. This work sought to study molecular differences between LPA and IMA, and explore their biological meanings. A cohort of LPA and AMI has been studied in regard of clinical characteristics and oncogenic drivers and samples from this cohort were exploited. An immunohistochemical study of expression of mucins MUC1, 2, 5B, 5AC and 6 in surgical samples of 27 LPA and 27 IMA showed different profile of expression between LPA and IMA. MUC1 expression was associated to MUC1 and MUC5AC, 5B and 6 to IMA. MUC1 was associated to EGFR mutations and MUC5B and 5AC to KRAS mutations. One NRG1 rearrangement was detected by FISH in one in 25 IMA. The CXCL10 chemokine was overexpressed in bronchoalveolar lavage fluid (BALF) supernatants of IMA (n=38) compared to LPA (n=25). This overexpression was linked to worse prognosis. The cytokine/receptor axis CXCL10/CXCR3-A was overexpressed in IMA and promoted migration of mucinous tumoral cells and drived tumoral expression of VEGF. VEGF from BALF of patients significantly enhanced human lung endothelial tubes formation in vitro which was inhibited by anti-VEGF bevacizumab. CXCL10/CXCR3 and VEGF could present valuable therapeutic targets in IMA. These results improve knowledge in biology of LPA and AMI and identify new lines of research which could lead to development of new therapies.

Les cancers colorectaux (CCR) constituent un véritable problème de santé publique. En France, en 2015, ils se situent au 3ème rang des cancers et au 2ème rang des décès par cancer, en raison d’un diagnostic souvent tardif et de réponses variables aux thérapeutiques. L’amélioration des tests de dépistage ces vingt dernières années n’a pas significativement réduit la morbi/mortalité liée au CCR et une meilleure caractérisation des différents sous-types moléculaires reste importante pour l’identification de nouveaux biomarqueurs. Les tumeurs colorectales sont hétérogènes tant sur le plan clinico-pathologique que moléculaire, issues de différentes voies de cancérogenèse. Les tumeurs de la voie festonnée représentent 20 à 30% des CCR. Elles sont caractérisées par une instabilité épigénétique (CpG Island Methylation Phenotype, CIMP), une instabilité microsatellitaire (MSI) et des mutations fréquentes du gène BRAF. Sur le plan phénotypique, ce sont des tumeurs volontiers mucisécrétantes surexprimant les mucines MUC2 et MUC5AC. L’identification précoce de leurs précurseurs reste actuellement un enjeu, d’autant que la séquence carcinogénétique des tumeurs festonnées serait particulièrement rapide.Dans cette étude, nous avons déterminé les caractéristiques clinico-pathologiques et moléculaires d’une série de cancers et polypes colorectaux et évalué l’intérêt des gènes de mucines MUC2 et MUC5AC pour classer les polypes festonnés et identifier les lésions précurseurs des cancers CIMP/MSI.L’étude a porté sur 418 CCR et 330 polypes coliques, incluant 218 polypes festonnés et 112 adénomes conventionnels, dont nous avons déterminé le profil moléculaire (mutations KRAS/BRAF, MSI, CIMP, méthylation MGMT, MLH1), ainsi que le profil d’expression et de méthylation des gènes de mucines MUC2 et MUC5AC. Les résultats ont été comparés aux données cliniques et anatomo-pathologiques.Nous montrons que l’hypométhylation du gène MUC5AC est un marqueur spécifique des CCR CIMP/MSI, indépendant des données clinico-pathologiques. De plus, nous montrons que l’hypométhylation de MUC5AC est un évènement précoce qui est spécifiquement associé aux polypes hyperplasiques de type microvésiculaire (MVHP) et adénomes festonnés sessiles (SSA), suggérant une filiation entre ces deux lésions, qui seraient les précurseurs des CCR CIMP/MSI. L’hypométhylation de MUC5AC était par ailleurs très spécifique des lésions festonnées mutées BRAF, CIMP ou MSI.En conclusion, nos résultats suggèrent un rôle de la mucine MUC5AC dans le développement des tumeurs coliques de la voie festonnée. L’hypométhylation du gène MUC5AC est un évènement précoce qui pourrait avoir un intérêt pour le diagnostic des polypes festonnés, en particulier lorsque la morphologie est ambiguë, et pour l’identification précoce des lésions à potentiel malin. De plus, nos résultats suggèrent que certains MVHP pourraient progresser en SSA et en CCR CIMP/MSI, d’où l’importance de réaliser des biopsies des polypes festonnés lors de l'endoscopie afin de repérer le sous-type microvésiculaire parmi les polypes hyperplasiques colorectaux, qui pourrait, bénéficier d’une surveillance minimale. / Colorectal cancer (CRC) is a major public health problem yet it remains the third most common and the second deadliest cancer for both men and women in the United States and in Europe, owing to diagnosis at advanced stage and variable response to the treatments. However, the incidence and mortality appear to be steadily declining in countries with programmatic screening and it remains critical to characterize CRC molecular subtypes to identify new biomarkers. CRC display a wide clinicopathological and molecular heterogeneity and arise from different carcinogenesis pathway. Approximately 20% to 30% of CRC occur by the means of the serrated neoplasia pathway. CRC from the serrated pathway are associated with frequent epigenetic instability (CIMP, CpG island methylator phenotype) which causes most sporadic microsatellite instability (MSI) CRC through epigenetic inactivation of MLH1 and frequent BRAF mutation. CRC from the serrated pathway frequently display a mucinous pattern and are prone to express secreted mucins MUC2 and MUC5AC. Early identification of serrated pathway precursor lesions is currently challenging since the progression to adenocarcinoma in this pathway is particularly brief.We assessed in this study clinicopathological and molecular features of colorectal carcinomas and polyps and we analyzed the interest of mucin genes MUC2 and MUC5AC to classify serrated polyps and to identify the precursor lesions of CIMP/MSI carcinomas._x000D_A series of 418 CRC and 330 polyps was included in the study, with 218 serrated polyps and 112 conventional adenomas. We assessed the molecular profile (KRAS/BRAF mutations, MSI, CIMP, MGMT methylation, MLH1) and the expression and methylation profile of MUC2 and MUC5AC genes and further correlation with clinical and pathological data were performed.We show that MUC5AC hypomethylation is a specific marker of CIMP/MSI CRC, independently of other clinical or pathological factors. We show moreover than MUC5AC hypomethylation is an early event of carcinogenesis, specific to microvesicular hyperplastic polyps (MVHP) and sessile serrated adenoma (SSA) suggesting a filiation between these two lesions and also a progression of MVHP to SSA, SSA with dysplasia, and then to MSI/CIMP CRC. MUC5AC hypomethylation was moreover highly specific of BRAF mutated, CIMP or MSI serrated lesions.In conclusion, our results suggest that the MUC5AC mucin is involved/plays a role in the development/progression of colorectal tumors of the serrated pathway. MUC5AC hypomethylation occurs early during carcinogenesis and may be of interest for the diagnosis of serrated polyp especially in the presence of ambiguous morphology and to early detection of polyps carrying a malignant potential. Our results suggest moreover that some MVHP may progress to SSA and CIMP/MSI CRCs highlighting the importance to perform biopsy of serrated polyps during endoscopy to identify microvesicular subtype among colorectal hyperplastic polyps, which could require a minimal surveillance.