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Early detection of adenomatous polyposis coli in Gardner's syndrome.

Gardner's syndrome, an autosomal dominant disorder, consists of multiple polyposis of the colon associated with various soft- and hard-tissue tumors. The appearance of adenomatous hyperplasia and polyposis in at-risk patients before adolescence has not been full appreciated. Four preadolescent children from a kindred with Gardner's syndrome were examined by use of colonoscopy and mucosal biopsy. In three children (18 months, 6 years, and 9 years old) adenomatous hyperplasia or polyposis was found. The colon of the fourth child (3 years old) was normal. The three affected children were asymptomatic. The youngest had a barium enema and results were normal. The oldest child had polyps. Biopsies revealed focal atypical hyperplasia of the glands with pseudostratification of the epithelial cells, frequent mitotic figures, and the absence of goblet cells. More severe manifestations were noted in the splenic flexure than in the sigmoid flexure or rectum. The youngest patient showed early adenomatous hyperplasia characterized by a marked reduction of the goblet cells, especially in the surface epithelium. Colonoscopy and mucosal biopsies are mandatory in at-risk children. By deferring colonic examination until adolescence, a patient is placed at risk for malignant degeneration of the adenomatous tumor.

Adenoma

A novel insertion/deletion in APC promotor 1B is associated with both gastric and colon polyposis.

Pathogenic variants in the APC gene are classically associated with autosomal dominant familial adenomatous polyposis (FAP), characterized by tens-to-thousands of colonic adenomatous polyps and a high-penetrance predisposition to colorectal cancer. More recently, specific PVs in the YY1 binding motif of APC promoter 1B have been associated with autosomal dominant gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), characterized by tens-to-thousands of fundic gland polyps and a predisposition to gastric cancer but which are only rarely associated with features consistent with FAP. Although management guidelines currently treat FAP and GAPPS as mutually exclusive conditions, the extent of phenotypic overlap is not well-characterized. Here, we present a multi-clinic and -laboratory collaboration reporting a previously undescribed APC promoter 1B insertion/deletion likely pathogenic variant in a family with mixed GAPPS and FAP phenotype. The family proband is a female of unspecified white ancestry. She was diagnosed with GAPPS at age 30 and, after developing gastric cancer at age 39, underwent curative gastrectomy. She is now 61 with a cumulative history of between 50 and 100 colon adenomas and recently completed subtotal colectomy. Her multi-gene panel testing in 2022 demonstrated a likely pathogenic insertion/deletion (indel) within the APC promoter 1B YY1 binding motif (APC c.-192_-191delATinsTAGCAAGGG). Review of a four-generation pedigree revealed the ages of gastric cancer presentation in the family ranged from 39-60's, with advanced gastric polyposis and prophylactic gastrectomy as early as ages 11 and 13 in the proband's daughter and nephew, respectively. Six of 10 (60%) family members known or presumed to carry the APC likely pathogenic variant underwent colectomy or hemicolectomy due to colon polyposis. The youngest known carrier in the family is a 12-year-old female, and the oldest living carrier is the proband's brother, age 66. A novel APC indel causes concomitant GAPPS and FAP presentations in this previously unreported large kindred. Mixed gastric and colon phenotypes have been rarely described in GAPPS families and the ages of presentation of gastric polyposis are strikingly young in the current family with prophylactic gastrectomies completed as early as age 11 and 13. These ages are significantly younger than the 15 years of age at which national guidelines currently recommend initiation of EGD for screening in GAPPS. Although the mechanism for this combined GAPPS-FAP phenotype is unclear, patients in this family and those with similar APC promoter 1B variants should be offered both gastric and colon cancer risk management.

Adult

Familial polyposis coli: heterogeneous polyp expression in 2 kindreds.

We describe 2 extended kindreds supposedly manifesting familial multiple adenomatous polyposis coli (FPC), but which show marked heterogeneity in the phenotypic expression of colorectal adenomatous polyps. In one family, 2 individuals had diffuse polyposis at very early ages (7 and 10 years), while 6 others (aged 23 to 72 years) had solitary polyps only. Of the patients with solitary polyps, 2 had associated colonic malignancies (ages 26 and 35), while another had a prophylactic colectomy performed at age 46. In the second family, 5 of the 11 patients with evidence of polyps showed the classical presentation of FPC, while the remainder showed marked phenotypic variation. The marked variability in frequency and location of colon polyps points to the need to reassess our traditional criteria for diagnosis of FPC. The high risk of early onset colon cancer in patients from these families who have the most minimal manifestation, namely isolated polyps, recommends more careful scrutiny of supposedly unaffected members of all FPC kindreds.

Adult

Interaction of Galpha 12 and Galpha 13 with the cytoplasmic domain of cadherin provides a mechanism for beta -catenin release.

The G12 subfamily of heterotrimeric G proteins, comprised of the alpha-subunits Galpha12 and Galpha13, has been implicated as a signaling component in cellular processes ranging from cytoskeletal changes to cell growth and oncogenesis. In an attempt to elucidate specific roles of this subfamily in cell regulation, we sought to identify molecular targets of Galpha12. Here we show a specific interaction between the G12 subfamily and the cytoplasmic tails of several members of the cadherin family of cell-surface adhesion proteins. Galpha12 or Galpha13 binding causes dissociation of the transcriptional activator beta-catenin from cadherins. Furthermore, in cells lacking the adenomatous polyposis coli protein required for beta-catenin degradation, expression of mutationally activated Galpha12 or Galpha13 causes an increase in beta-catenin-mediated transcriptional activation. These findings provide a potential molecular mechanism for the previously reported cellular transforming ability of the G12 subfamily and reveal a link between heterotrimeric G proteins and cellular processes controlling growth and differentiation.

Adenocarcinoma

Development of a new flippase-dependent mouse model for red fluorescence-based isolation of KRASG12D oncogene-expressing tumor cells.

Proto-oncogene KRAS, GTPase (KRAS) is one of the most intensively studied oncogenes in cancer research. Although several mouse models allow for regulated expression of mutant KRAS, selective isolation and analysis of transforming or tumor cells that produce the KRAS oncogene remains a challenge. In our study, we present a knock-in model of oncogenic variant KRASG12D that enables the "activation" of KRASG12D expression together with production of red fluorescent protein tdTomato. Both proteins are expressed from the endogenous Kras locus after recombination of a transcriptional stop box in the genomic DNA by the enzyme flippase (Flp). We have demonstrated the functionality of the allele termed RedRas (abbreviated KrasRR) under in vitro conditions with mouse embryonic fibroblasts and organoids and in vivo in the lung and colon epithelium. After recombination with adenoviral vectors carrying the Flp gene, the KrasRR allele itself triggers formation of lung adenomas. In the colon epithelium, it causes the progression of adenomas that are triggered by the loss of tumor suppressor adenomatous polyposis coli (APC). Importantly, cells in which recombination has successfully occurred can be visualized and isolated using the fluorescence emitted by tdTomato. Furthermore, we show that KRASG12D production enables intestinal organoid growth independent of epidermal growth factor (EGF) signaling and that the KRASG12D function is effectively suppressed by specific inhibitor MRTX1133.

Animals

Risk of desmoid tumor based on APC pathogenic variant location and surgical history in familial adenomatous polyposis: a U.S. community cohort study.

Desmoid tumors (DT) are a leading cause of morbidity and mortality in patients with familial adenomatous polyposis (FAP), yet available data on DT risk remain limited and have been largely derived from large registries or tertiary referral centers. Risk in community-based U.S. populations is poorly defined, which hinders presurgical counseling. We conducted a retrospective cohort study of patients with pathogenic or likely pathogenic variants (PV/LPV) in APC identified through the Kaiser Permanente Northern California Electronic Database, a community-based system serving 4.6 million members. We evaluated the association of APC PV/LPV location and prior abdominal surgery with DT risk using multivariable logistic regression, adjusting for sex, race and ethnicity, and family history. Among 328 patients with FAP, 36 (11.0%) developed DT. DT risk was highest when the APC variant was centrally located (codon 600-1600). Family history was independently associated with increased risk (adjusted odds ratio [aOR] 4.34; 95% confidence interval [CI] 1.12-16.86). All colorectal surgeries were associated with a significantly elevated DT risk: ileostomy (aOR 12.07; 2.10-69.47), subtotal colectomy with ileorectal anastomosis (aOR 9.03; 1.63-49.96), and total proctocolectomy with ileal pouch-anal anastomosis (aOR 10.98; 2.12-56.81). In contrast, non-colorectal surgery was not associated with increased risk (aOR 0.73). In this large community-based U.S. cohort, central APC variant location, family history, and colorectal surgery were associated with increased DT risk. Our findings extend the current literature on DT risk in FAP and help refine presurgical risk-stratification and counseling for these patients.

Humans

ACG Clinical Guideline: Diagnosis and Management of Adenomatous Colorectal Polyposis Syndromes.

The hereditary adenomatous colorectal polyposis syndromes are incurable, systemic, cancer risk predisposition syndromes with substantial morbidity and mortality. They differ in their mode of inheritance, age at disease onset, phenotypic expression, and cancer risk. The most common cancer risks involve the gastrointestinal tract including the colon, rectum, duodenum, ampulla, and stomach. Identifying these syndromes through personal and family history risk assessment and germline genetic testing, along with timely surgical and endoscopic management, can reduce cancer incidence and mortality. These guidelines use the Grading of Recommendations, Assessment, Development, and Evaluation methodology to provide clinical guidance on the selection of individuals who should undergo a risk assessment for a hereditary adenomatous colorectal polyposis syndrome, modality and timing of germline genetic testing, cancer risk mitigation through endoscopic and surgical interventions, and the role of chemoprevention. This document reviews the approach to genetic testing in patients with phenotypic colorectal polyposis and the impact of presymptomatic diagnosis in families with a known familial germline pathogenic variant or clinical features suggestive of a hereditary adenomatous polyposis syndrome. Management strategies for patients based on genetic test results or without genetic testing are provided. We also review colorectal and extracolonic phenotypic benign and malignant manifestations of the known hereditary syndromes with a focus on the 2 most common hereditary colorectal polyposis syndromes: familial adenomatous polyposis and MUTYH-associated polyposis. The document concludes with recommendations on polyposis and cancer risk mitigation strategies and highlights updates to management since the previous guideline was published.

Humans

Genomic and molecular landscape of early onset colorectal cancer: Emerging insights and clinical implications-A systematic review.

BACKGROUND: Early onset colorectal cancer, defined as colorectal malignancy occurring before age 50, has been rising globally. Increasing molecular evidence suggests that early onset colorectal cancer is not merely a premature form of late-onset colorectal cancer but a distinct biologic entity with unique genomic and transcriptomic profiles. METHODS: A systematic PubMed search using the terms "early onset colorectal cancer," "genomic," and "molecular" identified 270 records. Eighteen original studies met the inclusion criteria and were supplemented by references from selected articles. Extracted data encompassed clinicopathologic characteristics, genomic and epigenetic alterations, and dysregulated signaling pathways distinguishing early onset colorectal cancer from late-onset colorectal cancer. RESULTS: Evidence from approximately 19,888 patients with early onset colorectal cancer was synthesized across genomic, transcriptomic, and clinical data sets. Early onset colorectal cancer showed a predominance in distal and rectal sites, a slight male bias, and a higher prevalence among Hispanic and Asian populations. Compared with late-onset colorectal cancer, early onset colorectal cancer exhibited lower B-Raf proto-oncogene, serine/threonine kinase V600E mutation and CpG island methylator phenotype-high methylation frequencies but higher rates of tumor protein p53, Kirsten rat sarcoma viral oncogene homolog, and DNA-repair gene alterations. Distinct comutation patterns (F-box and WD repeat domain containing 7-neurogenic locus notch homolog protein 3-phosphoinositide-3-kinase regulatory subunit 1 and adenomatous polyposis coli-tumor protein p53) and overexpression of immediate-early response genes (Proto-Oncogene c-Fos, EGR1, DUSP1, and CYR61) defined its transcriptional landscape. Perturbations of Wingless/Integrated signaling pathway, mitogen-activated protein kinase, phosphoinositide 3-kinase-protein kinase B-mechanistic target of rapamycin, and DNA-repair pathways, along with global long interspersed nuclear element-1 hypomethylation, indicated heightened genomic instability. CONCLUSION: Early onset colorectal cancer develops through tumor protein p53-driven genomic instability and defective DNA repair rather than the canonical CpG island methylator phenotype-B-Raf proto-oncogene, serine/threonine kinase axis. Recognition of these molecular distinctions is essential for age-specific risk assessment, screening, and precision therapeutics. Further integrative studies are needed to elucidate environmental and genetic contributors and identify novel biomarkers and treatment targets.

Humans

Colorectal cancer. A study of 230 patients.

Clinical presentation, risk factors, investigations, pathology and treatment were examined in a retrospective review of 230 patients with colorectal cancer. Many patients presented with symptoms not usually associated with colorectal cancer, such as pain in the upper part of the abdomen, and rectal bleeding separate from the stool. Iron deficiency anaemia was an uncommon presentation. Over all, one-third of patients had at least one risk factor for colorectal cancer. Risk factors such as adenomatous polyps and family history of colorectal cancer were more common than inflammatory bowel disease and polyposis coli. Although a delay in diagnosis was recorded in one-quarter of patients, the finding of a negative correlation between duration of symptoms and extent of spread suggests that the length of the symptomatic illness is not an important factor in prognosis. Contrary to surgical and medical teaching, only 43% of cancers were in the rectum and rectosigmoid area, and, hence, within reach of the standard sigmoidoscope. Surgical resection was performed in 76% of patients. Forty-three per cent of patients who underwent surgery developed at least one postoperative complication resulting in a longer stay in hospital.

Adenocarcinoma

Polyposis coli. The clinical spectrum in adults.

Four patients are reported, to illustrate the wide spectrum of colonic polyps which may occur in multiple form in adults. Included are unusual cases of metaplastic and juvenile polyposis. The subject is reviewed, and the need for accurate histological diagnosis is stressed. The possibility that the difference between familial adenomatous polyposis and Gardner's syndrome may lie merely in the degree of expressivity of the associated extracolonic features is discussed. Surveillance of these patients for peri-ampullary neoplasms in the duodenum is considered. The interrelationship between familial adenomatous polyposis, juvenile polyposis and colorectal cancer is discussed.

Adenocarcinoma

Radiographic features of gastric polyps in familial adenomatosis coli.

Recent reports have noted a high frequency of elevated mucosal lesions of the stomach in patients with familial adenomatosis coli. This paper describes an additional 10 cases from six different families. Nine patients had sessile polyps in various portions of the stomach. Six of these have been examined histologically; two were adenomatous and four hyperplastic. The need for meticulous examination of the stomach in patients with multiple colonic polyposis is emphasized.

Adenoma

Ultrastructural study of the normal mucosa-adenoma-cancer sequence in the development of familial polyposis coli.

Ultrastructural changes that occurred in the colon epithelia of patients with familial polyposis coli were investigated. Criteria of gradation of the crescendo changes from the mucosa in the controls, through the "normal" mucosa between polyps and adenomas in various stages of dedifferentiation, to invasive carcinoma were established. Our criteria were based on the following requirements: a) vesiculation and increasing numbers of small electron-dense bodies (secretory granules) and lysosomes in the mature and immature absorptive cells, b) presence of immature and undifferiated cells, c) variation in the globlet cells and appearance of atypical secretory cells, and d) nuclear changes. The results illustrated the adenoma-carcinoma sequence and added strong evidence to support its occurrence. Furthermore, this ultrastructural study revealed cellular changes that preceded adenomatous growth and may be of value as markers of early stages of cancer. However, this study also revealed a close link between the function and morphology of the mucosal epithelium.

Adenocarcinoma