The APC tumour suppressor gene is the most commonly mutated gene in colorectal cancer (CRC). Loss of Apc in intestinal stem cells (ISCs) drives aberrant Wnt signalling and adenoma formation in mice 1 . We previously showed that a reduction in WNT-ligand secretion increases the ability of Apc-mutant ISCs to colonise a crypt (fixation) and accelerate tumourigenesis 2 . Here, we investigate key mechanistic processes whereby Apc-mutant cells gain a clonal advantage over wild-type counterparts to achieve fixation. We find that Apc-mutant cells are enriched for transcripts encoding several secreted Wnt antagonists, with Notum being the most highly expressed. Indeed, conditioned medium from Apc-mutant cells suppresses the growth of wild-type organoids in a Notum-dependent manner. Furthermore, Notum-secreting mutant clones actively inhibit the proliferation of surrounding wild-type crypt cells and drive their differentiation, thereby outcompeting them from the niche. Importantly, genetic or pharmacological inhibition of Notum is sufficient to abrogate the expansion of Apcmutant cells and their ability to form intestinal adenomas. Taken together, we demonstrate Notum as a key mediator during the early stages of mutation fixation, which can be targeted to restore wild-type cell competition and thus, offer novel preventative strategies for high-risk patients. MainThe colonic epithelium displays one of the highest mutation rates of all tissues 3,4 , with lossof-function mutations in the APC tumour suppressor considered a key early event in colorectal cancer (CRC) initiation 5 . For a mutation to be maintained within a crypt, it needs to become "fixed", by mutant cells outcompeting wild-type intestinal stem cells (ISC) from the crypt 6,7 .Previous studies revealed that Apc loss (or Kras activation) confer a clonal advantage to ISCs 7,8, increasing their probability of fixation/winning within the crypt and, in the case of Apc mutation, driving adenoma formation. Even though APC-deficient clones have an increased probability of "winning", they can still be stochastically eliminated from the ISC pool i.e. lose.This suggests uncovering the molecular mechanisms by which APC-deficient cells outcompete wild-type cells could lead to novel chemo-preventative approaches.APC is a negative regulator of Wnt signalling that functions as an integral part of the destruction complex, which directs the phosphorylation and degradation of β-catenin 9 . Since Apc-mutant tumours exhibit constitutive Wnt-pathway activation, we first sought to identify genes differentially upregulated in Apc-mutant cells relative to the normal intestinal epithelium.For this, we performed transcriptomic analysis of tumours that develop in VillinCre ER ;Apc fl/+ (hereafter VilCre ER ;Apc fl/+ ) mice following the sporadic loss of the remaining copy of Apc 10 , akin to human CRC 11 . As expected, Wnt-target genes were highly upregulated in these Apcmutant tumours (Extended Data Fig. 1a). The most highly upregulated gene was Notum (Fig. 1a), which encodes a secreted WNT...

Background Evidence is emerging that the incidence of colorectal cancer is increasing in young adults, but the descriptive epidemiology required to better understand these trends is currently lacking. Methods A population‐based cohort study was carried out including all adults aged 20–49 years diagnosed with colorectal cancer in England between 1974 and 2015. Data were extracted from the National Cancer Registration and Analysis Service database using ICD‐9/10 codes for colorectal cancer. Temporal trends in age‐specific incidence rates according to sex, anatomical subsite, index of multiple deprivation quintile and geographical region were analysed using Joinpoint regression. Results A total of 56 134 new diagnoses of colorectal cancer were analysed. The most sustained increase in incidence rate was in the group aged 20–29 years, which was mainly driven by a rise in distal tumours. The magnitude of incident rate increases was similar in both sexes and across Index of Multiple Deprivation quintiles, although the most pronounced increases in incidence occurred in the southern regions of England. Conclusion Colorectal cancer should no longer be considered a disease of older people. Changes in incidence rates should be used to inform future screening policy, preventative strategies and research agendas, as well as increasing public understanding that younger people need to be aware of the symptoms of colorectal cancer.

Two hundred eighty-five isolates of Campylobacter jejuni-Campylobacter coli from children with gastroenteritis at The Hospital for Sick Children (Toronto, Canada) over a three-year period were biotyped by the hippurate hydrolysis test and serotyped on the basis of thermostable, soluble antigens by the passive hemagglutination technique. Hippurate-negative strains (C. coli) were only 3.2% of the isolates. Ninety-seven percent of the isolates were serotypable with 55 antisera. About half of the strains belonged to one of four serotypes (2, 4, 3, or 1); about three-quarters belonged to one of 10 serotypes. Serotype 2 was consistently the commonest serotype in each of the three years of the study, accounting for 15%-20% of all isolates tested.

Level I, therapeutic study.

The aim of our study was to identify changes in secreted procathepsin B levels in a model of the human colorectal adenoma to carcinoma sequence and to determine the factors required for i t s extracellular activation.Conversion of the non-tumorigenic adenoma-derived cell line PC/AA to a highly tumorigenic phenotype (designated AAIC I / SBlO/M) was associated with an 8-fold increase in the presence of the proform of cathepsin B in 24 hr conditioned serum-free medium (SFM). In addition, mature enzyme was only detected in the cell lines of this model with increased malignant potential. This is in agreement with the findings of a previous study, in which mature cathepsin B was only present in the 24 hr conditioned SFM of cancer-derived cell lines and not in SFM from adenoma-derived cell lines.Having demonstrated a reduction in the pH of conditioned medium from cell lines with increased malignant potential, we used a range of specific proteinase inhibitors to show that an aspartyl proteinase was involved in the initial activation of procathepsin B. Consistent with this finding, we subsequently demonstrated an increased secretion of the aspartyl proteinase cathepsin D in the medium of the AA/CI /SBIO/M adenocarcinoma cells compared with the non-tumorigenic AA/C I cell line. Therefore, the presence of mature cathepsin B in the conditioned medium of the more malignant cell lines coincided with a reduction in pH and an increase in the amount of cathepsin D secreted.Data from the human colorectal derived adenoma to carcinoma sequence indicate that an in vivo mechanism may exist that, dependent on the simultaneous presence of both a tumour-generated acidic extracellular environment and an elevated secretion of procathepsin D, could result in the activation of latent procathepsin outside the cell.8 1996 Wiley-Liss, Inc.

Summary The cellular response. in terms of cell cycle arrest(s) and apoptosis. to radiation-induced DNA damage was studied. Experiments were performed on both mitogen-stimulated and resting peripheral blood lymphocytes (PBLs) from normal and cancer-prone (C-P) individuals. The C-P individuals comprised three patients carrying germline p53 mutations and three members of two families apparently without such mutations, but with an inherited defect which results in p53 deregulation as shown by high levels of stabilised p53 protein in normal tissues. Interestingly, mitogen-stimulated PBL, from both normal and C-P individuals failed to demonstrate a G, arrest after gamma radiation. However, a clear difference was seen in the apoptotic response to DNA damage, of PBL from normal and C-P individuals; PBLs from C-P individuals with inherited p53-related defects had a reduced apoptotic response (P = 0.0003). There was a wide margin of separation, with no overlap between the two groups, supporting the possibility of using this altered apoptotic response as a screening test. This simple and rapid procedure could be used to identify those individuals in a C-P family who carry germline p53-related defects. The method appears to detect both individuals with p53 mutations and those apparently without mutations but with other p53-related defects.Keywords: apoptosis; p53; cancer-prone families; cell cycle arrest p53 protein was discovered in 1979 by its property of binding to large T-antigen, the oncogene product of SV40 (Lane and Crawford, 1979;Linzer and Levine, 1979). In recent years it has become clear that p53 plays a central role in the cellular processes involved in recognition of, and response to, DNA damage. Following a variety of noxious stimuli, such as gamma or UV irradiation, an accumulation of p53 is seen in the nuclei of normal cells (Kastan et al., 1991Fritsche et al., 1993;Hall et al., 1993). The precise mechanisms by which p53 functions at the biochemical level are not yet clear but the recognition of DNA damage clearly involves more genes than p53 alone. p53 can act as a transcription factor for other genes and p53 protein forms complexes with a considerable number of other proteins. Recently, progress has been made in understanding the way in which p53 mediates apoptosis in cooperation with transcription factor E2F-1 (Wu and Levine, 1994). Similarly, recent discoveries have contributed to the understanding of the mechanism by which p53 may control cell cycle progression, by controlling expression of the p21 cyclin-dependent kinase regulator (Waga et al., 1994). The interactions are clearly complex but worthy of considerable study given the central role of p53 in maintaining genetic stability.Kastan et al. (1991, 1992) proliferation at all but rather be deleted via the process of apoptosis. p53 has been firmly implicated in this process following the induction of DNA damage (Clark et al., 1993;Lowe et al., 1993;Ryan et al., 1993). Secondly, it is not certain that a GI arrest is necessary for the p53 induction...

PRIMA-1 (p53 reactivation and induction

A p53 C-terminal peptide (aa 361-382, p53p), fused at its Cterminus to the minimal carrier peptide of antennapedia (17 aa, Ant; p53p-Ant), induced rapid apoptosis in human cancer cells, via activation of the Fas pathway. We examined p53p-Ant mechanism of action, toxicity in various human normal, non-malignant, pre-malignant and malignant cancer cells and investigated its biophysical characteristics. p53p-Ant selectively induced cell death in only pre-malignant or malignant cells in a p53-dependent manner and was not toxic to normal and non-malignant cells. p53p-Ant was more toxic to the mutant p53 than wild-type p53 phenotype in H1299 lung cancer cells stably expressing human temperature-sensitive p53 mutant 143Ala. Surface plasmon resonance (BIACORE) analysis demonstrated that this peptide had higher binding affinity to mutant p53 as compared to wild-type p53. p53p-Ant induced-cell death had the classical morphological characteristics of apoptosis and had no features of necrosis. The The p53 tumor suppressor gene is one of the most commonly mutated genes found in human malignancies. 1 More than 50% of human tumors, including breast cancers, are associated with missense mutations or deletions of p53 and most of the missense mutations map to the DNA-binding domain of the protein. 2,3 p53 protein functions in the transcription of growth inhibiting genes, apoptosis, cell cycle arrest and DNA repair. 4 -6 p53 is a sequencespecific transcription factor that transactivates a number of genes whose products are involved in cell growth regulation. These include p21 (a cyclin-dependent kinase inhibitor known to arrest the cell cycle mainly in G1/S phase), GADD45 for DNA repair and Bax and Fas/APO-1 for apoptosis. 7-11 p53 induced Fas-FADD binding and transiently sensitized cells to Fas-induced apoptosis. 12 Programmed cell death depends on conserved structural moieties that transmit and regulate the death signal. This is most evident in death receptors of the tumor necrosis factor receptor (TNF-R) super-family. The intracellular regions of the Fas/CD95 and TNFR1 death receptors have a moderately well conserved NH2-region of about 80 residues that is required for death signalling and has been called the 'death domain' (DD). 13,14 Fas/CD95 induces rapid apoptosis upon binding to Fas ligand through the autocrine/paracrine signalling pathway. 15 When activated, the intracellular death domain in Fas/CD95 binds to FADD/MORT-1 at its C-terminus, which then recruits caspase-8 to FADD. A member of the TNF ligand family identified more recently is TNF-related apoptosis-inducing ligand (TRAIL). TRAIL shows high homology to Fas Ligand and binds to the TRAIL receptor family. TRAILinduced caspase activation shares many of same caspases involved in Fas/CD95 and TNF-induced cell death mechanisms. 16 FADD/ MORT-1 is a cytosolic adaptor protein, which is critical for signalling from Fas/APO-1 and other TNF-R family members. 17 Two protein interaction domains have been identified in FADD/ MORT-1. The C-terminal 'death domain' is needed for ...