-
European Journal of Gastroenterology &... Mar 2014Familial adenomatous polyposis is characterized by the development of multiple (>100) colorectal adenomas throughout the colorectum. This disorder can be caused by a... (Review)
Review
Familial adenomatous polyposis is characterized by the development of multiple (>100) colorectal adenomas throughout the colorectum. This disorder can be caused by a germline mutation in the adenomatous polyposis coli gene and can be diagnosed either clinically or genetically. After diagnosis with the condition, patients should undergo prophylactic proctocolectomy with a neoreservoir, usually an ileoanal pouch, at an appropriate time. Individuals with a family history of this disease who have not been diagnosed should be advised to attend genetic counseling and to enroll in appropriate clinical and genetic surveillance programs. Recent progress in endoscopic technology, including high-resolution endoscopy, capsule endoscopy, and double-balloon endoscopy, has made possible more detailed and wide-ranging investigation of the gastrointestinal tract. Although there has been limited evidence, further studies on these new endoscopic technologies might alter the surveillance strategies for familial adenomatous polyposis.
Topics: Adenomatous Polyposis Coli; Anticarcinogenic Agents; Capsule Endoscopy; Genes, APC; Genetic Testing; Germ-Line Mutation; Humans; Mutation; Population Surveillance; Proctocolectomy, Restorative
PubMed: 24161962
DOI: 10.1097/MEG.0000000000000010 -
PloS One 2020Computational algorithms are often used to assess pathogenicity of Variants of Uncertain Significance (VUS) that are found in disease-associated genes. Most...
Computational algorithms are often used to assess pathogenicity of Variants of Uncertain Significance (VUS) that are found in disease-associated genes. Most computational methods include analysis of protein multiple sequence alignments (PMSA), assessing interspecies variation. Careful validation of PMSA-based methods has been done for relatively few genes, partially because creation of curated PMSAs is labor-intensive. We assessed how PMSA-based computational tools predict the effects of the missense changes in the APC gene, in which pathogenic variants cause Familial Adenomatous Polyposis. Most Pathogenic or Likely Pathogenic APC variants are protein-truncating changes. However, public databases now contain thousands of variants reported as missense. We created a curated APC PMSA that contained >3 substitutions/site, which is large enough for statistically robust in silico analysis. The creation of the PMSA was not easily automated, requiring significant querying and computational analysis of protein and genome sequences. Of 1924 missense APC variants in the NCBI ClinVar database, 1800 (93.5%) are reported as VUS. All but two missense variants listed as P/LP occur at canonical splice or Exonic Splice Enhancer sites. Pathogenicity predictions by five computational tools (Align-GVGD, SIFT, PolyPhen2, MAPP, REVEL) differed widely in their predictions of Pathogenic/Likely Pathogenic (range 17.5-75.0%) and Benign/Likely Benign (range 25.0-82.5%) for APC missense variants in ClinVar. When applied to 21 missense variants reported in ClinVar and securely classified as Benign, the five methods ranged in accuracy from 76.2-100%. Computational PMSA-based methods can be an excellent classifier for variants of some hereditary cancer genes. However, there may be characteristics of the APC gene and protein that confound the results of in silico algorithms. A systematic study of these features could greatly improve the automation of alignment-based techniques and the use of predictive algorithms in hereditary cancer genes.
Topics: Adenomatous Polyposis Coli; Adenomatous Polyposis Coli Protein; Algorithms; Amino Acid Sequence; Computational Biology; Computer Simulation; Databases, Protein; Enhancer Elements, Genetic; Evolution, Molecular; Exons; Genes, APC; Genetic Variation; Humans; Mutation, Missense; Phylogeny; Protein Isoforms; RNA Splice Sites; Sequence Alignment
PubMed: 32750050
DOI: 10.1371/journal.pone.0233673 -
The Journal of Biological Chemistry 2021Hyperactivation of Wnt/β-catenin (canonical) signaling in colorectal cancers (CRCs) was identified in the 1990s. Most CRC patients have mutations in genes that encode... (Review)
Review
Hyperactivation of Wnt/β-catenin (canonical) signaling in colorectal cancers (CRCs) was identified in the 1990s. Most CRC patients have mutations in genes that encode components of the Wnt pathway. Inactivating mutations in the adenomatous polyposis coli (APC) gene, which encodes a protein necessary for β-catenin degradation, are by far the most prevalent. Other Wnt signaling components are mutated in a smaller proportion of CRCs; these include a FZD-specific ubiquitin E3 ligase known as ring finger protein 43 that removes FZDs from the cell membrane. Our understanding of the genetic and epigenetic landscape of CRC has grown exponentially because of contributions from high-throughput sequencing projects such as The Cancer Genome Atlas. Despite this, no Wnt modulators have been successfully developed for CRC-targeted therapies. In this review, we will focus on the Wnt receptor complex, and speculate on recent discoveries about ring finger protein 43regulating Wnt receptors in CRCs. We then review the current debate on a new APC-Wnt receptor interaction model with therapeutic implications.
Topics: Animals; Colonic Neoplasms; Genes, APC; Humans; Low Density Lipoprotein Receptor-Related Protein-6; Mutation; Receptors, Wnt; Signal Transduction; beta Catenin
PubMed: 34000297
DOI: 10.1016/j.jbc.2021.100782 -
Scientific Reports Dec 2021The tumor suppressor gene adenomatous polyposis coli (APC) is the initiating mutation in approximately 80% of all colorectal cancers (CRC), underscoring the importance...
The tumor suppressor gene adenomatous polyposis coli (APC) is the initiating mutation in approximately 80% of all colorectal cancers (CRC), underscoring the importance of aberrant regulation of intracellular WNT signaling in CRC development. Recent studies have found that early-onset CRC exhibits an increased proportion of tumors lacking an APC mutation. We set out to identify mechanisms underlying APC mutation-negative (APC) CRCs. We analyzed data from The Cancer Genome Atlas to compare clinical phenotypes, somatic mutations, copy number variations, gene fusions, RNA expression, and DNA methylation profiles between APC and APC mutation-positive (APC) microsatellite stable CRCs. Transcriptionally, APC CRCs clustered into two approximately equal groups. Cluster One was associated with enhanced mitochondrial activation. Cluster Two was strikingly associated with genetic inactivation or decreased RNA expression of the WNT antagonist RNF43, increased expression of the WNT agonist RSPO3, activating mutation of BRAF, or increased methylation and decreased expression of AXIN2. APC CRCs exhibited evidence of increased immune cell infiltration, with significant correlation between M2 macrophages and RSPO3. APC CRCs comprise two groups of tumors characterized by enhanced mitochondrial activation or increased sensitivity to extracellular WNT, suggesting that they could be respectively susceptible to inhibition of these pathways.
Topics: Adenomatous Polyposis Coli; Adenomatous Polyposis Coli Protein; Colorectal Neoplasms; DNA Copy Number Variations; DNA Methylation; Disease Progression; Genes, APC; Humans; Microsatellite Instability; Microsatellite Repeats; Mutation; Neoplastic Processes; Phenotype; Promoter Regions, Genetic; Wnt Signaling Pathway
PubMed: 34873211
DOI: 10.1038/s41598-021-02806-x -
Journal of Medical Genetics Nov 2023While constitutional pathogenic variants in the gene cause familial adenomatous polyposis, c.3920T>A; p.Ile1307Lys (I1307K) has been associated with a moderate... (Meta-Analysis)
Meta-Analysis
While constitutional pathogenic variants in the gene cause familial adenomatous polyposis, c.3920T>A; p.Ile1307Lys (I1307K) has been associated with a moderate increased risk of colorectal cancer (CRC), particularly in individuals of Ashkenazi Jewish descent. However, published data include relatively small sample sizes, generating inconclusive results regarding cancer risk, particularly in non-Ashkenazi populations. This has led to different country/continental-specific guidelines regarding genetic testing, clinical management and surveillance recommendations for I1307K. A multidisciplinary international expert group endorsed by the International Society for Gastrointestinal Hereditary Tumours (InSiGHT), has generated a position statement on the I1307K allele and its association with cancer predisposition. Based on a systematic review and meta-analysis of the evidence published, the aim of this document is to summarise the prevalence of the I1307K allele and analysed the evidence of the associated cancer risk in different populations. Here we provide recommendations on the laboratory classification of the variant, define the role of predictive testing for I1307K, suggest recommendations for cancer screening in I1307K heterozygous and homozygous individuals and identify knowledge gaps to be addressed in future research studies. Briefly, I1307K, classified as pathogenic, low penetrance, is a risk factor for CRC in individuals of Ashkenazi Jewish origin and should be tested in this population, offering carriers specific clinical surveillance. There is not enough evidence to support an increased risk of cancer in other populations/subpopulations. Therefore, until/unless future evidence indicates otherwise, individuals of non-Ashkenazi Jewish descent harbouring I1307K should be enrolled in national CRC screening programmes for average-risk individuals.
Topics: Humans; Genetic Predisposition to Disease; Adenomatous Polyposis Coli; Colorectal Neoplasms; Genes, APC; Risk Factors; Jews
PubMed: 37076288
DOI: 10.1136/jmg-2022-108984 -
Mutation Research Nov 2010With improvements to DNA sequencing technologies, including the advent of massively parallel sequencing to perform "deep sequencing" of tissue samples, the ability to... (Review)
Review
With improvements to DNA sequencing technologies, including the advent of massively parallel sequencing to perform "deep sequencing" of tissue samples, the ability to determine all of the nucleotide variations in a tumor becomes a possibility. This information will allow us to more fully understand the heterogeneity within each tumor, as well as to identify novel genes involved in cancer development. However, the new challenge that arises will be to interpret the pathogenic significance of each genetic variant. The enormity and complexity of this challenge can be demonstrated by focusing on just the genes involved in the hereditary colon cancer syndromes, familial adenomatous polyposis (FAP) and hereditary non-polyposis coli (HNPCC). The genes responsible for each disease were identified almost two decades ago -APC for FAP and the MMR genes for HNPCC - and a large number of germline variations have been identified in these genes in hereditary cancer patients. However, relating the effect of an individual genotype to phenotype is not always straightforward. This review focuses on the roles of the APC and MMR genes in tumor development and the work that has been done to relate different variants in each gene to functional aberrations and ultimately tumorigenesis. By considering the work that has already been done on two well-defined diseases with clear genetic associations, one can begin to understand the challenges that lie ahead as new genes and gene mutations are discovered through tumor sequencing.
Topics: Adenomatous Polyposis Coli; Colorectal Neoplasms; Colorectal Neoplasms, Hereditary Nonpolyposis; DNA Mismatch Repair; Genes, APC; Genetic Variation; Genotype; Humans; Mutation; Phenotype
PubMed: 19766128
DOI: 10.1016/j.mrfmmm.2009.09.004 -
BMC Cancer Jan 2022Melanoma-intrinsic activated β-catenin pathway, the product of the catenin beta 1 (CTNNB1) gene, has been associated with low/absent tumor-infiltrating lymphocytes,...
BACKGROUND
Melanoma-intrinsic activated β-catenin pathway, the product of the catenin beta 1 (CTNNB1) gene, has been associated with low/absent tumor-infiltrating lymphocytes, accelerated tumor growth, metastases development, and resistance to anti-PD-L1/anti-CTLA-4 agents in mouse melanoma models. Little is known about the association between the adenomatous polyposis coli (APC) and CTNNB1 gene mutations in stage IV melanoma with immunotherapy response and overall survival (OS).
METHODS
We examined the prognostic significance of somatic APC/CTNNB1 mutations in the Cancer Genome Atlas Project for Skin Cutaneous Melanoma (TCGA-SKCM) database. We assessed APC/CTNNB1 mutations as predictors of response to immunotherapies in a clinicopathologically annotated metastatic patient cohort from three US melanoma centers.
RESULTS
In the TCGA-SKCM patient cohort (n = 434) presence of a somatic APC/CTNNB1 mutation was associated with a worse outcome only in stage IV melanoma (n = 82, median OS of APC/CTNNB1 mutants vs. wild-type was 8.15 vs. 22.8 months; log-rank hazard ratio 4.20, p = 0.011). APC/CTNNB1 mutation did not significantly affect lymphocyte distribution and density. In the 3-melanoma institution cohort, tumor tissues underwent targeted panel sequencing using two standards of care assays. We identified 55 patients with stage IV melanoma and APC/CTNNB1 genetic aberrations (mut) and 169 patients without (wt). At a median follow-up of more than 25 months for both groups, mut compared with wt patients had slightly more frequent (44% vs. 39%) and earlier (66% vs. 45% within six months from original diagnosis of stage IV melanoma) development of brain metastases. Nevertheless, time-to-development of brain metastases was not significantly different between the two groups. Fortunately, mut patients had similar clinical benefits from PD-1 inhibitor-based treatments compared to wt patients (median OS 26.1 months vs. 29.9 months, respectively, log-rank p = 0.23). Less frequent mutations in the NF1, RAC1, and PTEN genes were seen in the mut compared with wt patients from the 3-melanoma institution cohort. Analysis of brain melanoma tumor tissues from a separate craniotomy patient cohort (n = 55) showed that melanoma-specific, activated β-catenin (i.e., nuclear localization) was infrequent (n = 3, 6%) and not prognostic in established brain metastases.
CONCLUSIONS
APC/CTNNB1 mutations are associated with a worse outcome in stage IV melanoma and early brain metastases independent of tumor-infiltrating lymphocyte density. However, PD1 inhibitor-based treatments provide comparable benefits to both mut and wt patients with stage IV melanoma.
Topics: Adult; Aged; Aged, 80 and over; Female; Genes, APC; Humans; Lymphocytes, Tumor-Infiltrating; Male; Melanoma; Middle Aged; Mutation; Neoplasm Staging; Prognosis; Proportional Hazards Models; Skin Neoplasms; beta Catenin; Melanoma, Cutaneous Malignant
PubMed: 34986841
DOI: 10.1186/s12885-021-08908-z -
European Journal of Cancer (Oxford,... Sep 2010While germline mutations in the adenomatous polyposis coli (APC) gene cause the hereditary colon cancer syndrome (familial adenomatous polyposis (FAP)), the role of...
While germline mutations in the adenomatous polyposis coli (APC) gene cause the hereditary colon cancer syndrome (familial adenomatous polyposis (FAP)), the role of common germline APC variants in sporadic adenomatous polyposis remains unclear. We studied the association of eight APC single nucleotide polymorphisms (SNPs), possibly associated with functional consequences, and previously identified gene-environment (dietary fat intake and hormone replacement therapy (HRT) use) interactions, in relation to advanced colorectal adenoma in 758 cases and 767 sex- and race-matched controls, randomly selected from the screening arm of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Cases had at least one verified advanced adenoma of the distal colon; controls, a negative sigmoidoscopy. We did not observe an association between genotypes for any of the eight APC SNPs and advanced distal adenoma risk (P(global gene-based)=0.92). Frequencies of identified common haplotypes did not differ between cases and controls (P(global haplotype test)=0.97). However, the risk for advanced distal adenoma was threefold higher for one rare haplotype (cases: 2.7%; controls: 1.6%) (odds ratio (OR)=3.27; 95% confidence interval (CI)=1.08-9.88). The genetic association between D1822V and advanced distal adenoma was confined to persons consuming a high-fat diet (P(interaction)=0.03). Similar interactions were not observed with HRT use. In our large, nested case-control study of advanced distal adenoma and clinically verified adenoma-free controls, we observed no association between specific APC SNPs and advanced adenoma. Fat intake modified the APC D1822V-adenoma association, but further studies are warranted.
Topics: Adenomatous Polyposis Coli; Aged; Case-Control Studies; Dietary Fats; Female; Genes, APC; Genotype; Germ-Line Mutation; Haplotypes; Hormone Replacement Therapy; Humans; Male; Middle Aged; Polymorphism, Single Nucleotide; Risk Factors
PubMed: 20510605
DOI: 10.1016/j.ejca.2010.04.020 -
Philosophical Transactions of the Royal... Jun 1998The Min (multiple intestinal neoplasia) strain of the laboratory mouse and its derivatives permit the fundamental study of factors that regulate the transition between... (Review)
Review
The Min (multiple intestinal neoplasia) strain of the laboratory mouse and its derivatives permit the fundamental study of factors that regulate the transition between normal and neoplastic growth. A gene of central importance in mediating these alternative patterns of growth is Apc, the mouse homologue of the human adenomatous polyposis coli (APC) gene. When adenomas form in the Min mouse, both copies of the Apc gene must be inactivated. One copy is mutated by the nonsense Apc allele carried in heterozygous form in this strain. The other copy can be silenced by any of several mechanisms. These range from loss of the homologue bearing the wild-type Apc allele; to interstitial deletions surrounding the wild-type allele; to intragenic mutation, including nonsense alleles; and finally, to a reduction in expression of the locus, perhaps owing to mutation in a regulatory locus. Each of these proposed mechanisms may constitute a two-hit genetic process as initially posited by Knudson; however, apparently the two hits could involve either a single locus or two loci. The kinetic order for the transition to adenoma may be still higher than two, if polyclonal adenomas require stronger interactions than passive fusion. The severity of the intestinal neoplastic phenotype of the Min mouse is strongly dependent upon loci other than Apc. One of these, Mom1, has now been rigorously identified at the molecular level as encoding an active resistance conferred by a secretory phospholipase. Mom1 acts locally within a crypt lineage, not systemically. Within the crypt lineage, however, its action seems to be non-autonomous: when tumours arise in Mom1 heterozygotes, the active resistance allele is maintained in the tumour (MOH or maintenance of heterozygosity). Indeed, the secretory phospholipase is synthesized by post-mitotic Paneth cells, not by the proliferative cells that presumably generate the tumour. An analysis of autonomy of modifier gene action in chimeric mice deserves detailed attention both to the number of genetic factors for which an animal is chimeric and to the clonal structure of the tissue in question. Beyond Mom1, other loci can strongly modify the severity of the Min phenotype. An emergent challenge is to find ways to identify the full set of genes that interact with the intestinal cancer predisposition of the Min mouse strain. With such a set, one can then work, using contemporary mouse genetics, to identify the molecular, cellular and organismal strategies that integrate their functions. Finally, with appropriately phenotyped human families, one can investigate by a candidate approach which modifying factors influence the epidemiology of human colon cancer. Even if a candidate modifier does not explain any of the genetic epidemiology of colon cancer in human populations, modifier activities discovered by mouse genetics provide candidates for chemopreventive and/or therapeutic modalities in the human.
Topics: Adenoma; Adenomatous Polyposis Coli; Animals; Chromosome Deletion; Genes, APC; Genes, Regulator; Humans; Intestinal Mucosa; Intestinal Neoplasms; Mice
PubMed: 9684289
DOI: 10.1098/rstb.1998.0256 -
International Journal of Molecular... Feb 2023The activation of Wnt/β-catenin signalling is a prerequisite for odontogenesis. APC, a member of the AXIN-CK1-GSK3β-APC β-catenin destruction complex, functions to...
The activation of Wnt/β-catenin signalling is a prerequisite for odontogenesis. APC, a member of the AXIN-CK1-GSK3β-APC β-catenin destruction complex, functions to modulate Wnt/β-catenin signalling to establish regular teeth number and positions. APC loss-of-function mutations are associated with the over-activation of WNT/β-catenin signalling and subsequent familial adenomatous polyposis (FAP; MIM 175100) with or without multiple supernumerary teeth. The ablation of Apc function in mice also results in the constitutive activation of β-catenin in embryonic mouse epithelium and causes supernumerary tooth formation. The objective of this study was to investigate if genetic variants in the gene were associated with supernumerary tooth phenotypes. We clinically, radiographically, and molecularly investigated 120 Thai patients with mesiodentes or isolated supernumerary teeth. Whole exome and Sanger sequencing identified three extremely rare heterozygous variants (c.3374T>C, p.Val1125Ala; c.6127A>G, p.Ile2043Val; and c.8383G>A, p.Ala2795Thr) in in four patients with mesiodentes or a supernumerary premolar. An additional patient with mesiodens was compound as heterozygous for two variants (c.2740T>G, p.Cys914Gly, and c.5722A>T, p.Asn1908Tyr). Rare variants in in our patients are likely to contribute to isolated supernumerary dental phenotypes including isolated mesiodens and an isolated supernumerary tooth.
Topics: Animals; Humans; Mice; Adenomatous Polyposis Coli; Adenomatous Polyposis Coli Protein; beta Catenin; Genes, APC; Tooth, Supernumerary
PubMed: 36901686
DOI: 10.3390/ijms24054255