Adenomatosis Polyposis Coli Gene Research Articles

OncomiR Structure and Network Prediction on Adenomatosis Polyposis Coli (APC) Gene Silencing Regulation in Colorectal Cancer

The emergence of colorectal cancer cells is associated with the inactivation of the adenomatosis polyposis coli (APC) gene which increases the activity of ß-catenin, one of which is due to oncomiRNA (cancer-inducing microRNA). miR-135a/b-5p and miR-494-3p were thought to be involved in silencing the APC gene and increasing cell proliferation and could potentially be used as anti-miR targets. However, there is a need for an in-depth evaluation of the involvement of the oncomiR as a therapeutic target in preventing the formation of CRC. Therefore, this study aimed to predict the mechanism of inhibition of oncomiR hsa-miR-135a/b, and has-miR-494-3p against APC in the Wnt/ß-catenin signaling pathway. This research was conducted through in silico analysis using a web-based application to describe the stability of the secondary structure, binding position on mRNA, and conserved nucleotides that support biological activity. The data obtained were then used to develop miRNA interaction networks with APCs on the CRC-associated Wnt/ß-catenin signaling pathway. This study suggests that miR-135a-5p, and miR-135b-5p probably evolved earlier in the evolutionary evolution of the conserved oncomiR CRC in various vertebrate species, whereas miR-494-3p is more conserved and commonly found in mammals. The biological activity of miR-494-3p is likely to be more stable and patent to bind to APC gene mRNA and trigger CRC cell proliferation. Furthermore, miR-135a/b-5p and miR-494-3p have the potential to be developed as targets for anti-miR-based transcriptomic therapy as well as for early diagnosis of CRC development. Anti-miR therapy will likely need to involve more than 1 miRNA, as each gene has more than 1 miRNA binding site. HIGHLIGHTS Important findings in this study include: Adenomatosis polyposis coli (APC) gene silencing in CRC cases correlates to oncomiR activity of miR-135a/b-3p and miR-494-3p miR-494 tends to inhibit the translation of APC mRNA more strongly than miR-135a/b-5p represented by lower context++ score in mRNA binding simulation In some cases, CRC formation was also caused by silencing activity by oncomiRs, such as miR-135a-5p, miR-135b-5p and miR-494-3p which inhibited APC gene mRNA translation This study suggests that miR-135a-5p, and miR-135b-5p likely evolved earlier in the evolution of conserved CRC development in various vertebrate species, whereas miR-494-3p is more conserved and common in mammals Based on the biological activity miR-494-3p is likely to be more stable and potent to bind to the mRNA of the APC miR-135a/b-5p and miR-494-3p is potentially developed as targets for transcriptomic anti-miR-based therapy as well as for early diagnosis of CRC development GRAPHICAL ABSTRACT

A Japanese patient with ductal carcinoma of the prostate carrying an adenomatosis polyposis coli gene mutation: a case report

BackgroundDuctal carcinoma of the prostate is a histological subtype with a higher mortality than acinar adenocarcinoma. The number of cases is small and there are no treatment guidelines. We believe that this is the first report of ductal carcinoma of the prostate with an adenomatosis polyposis coli (APC) gene mutation in Japan.Case presentationAn 85-year-old man presented with gross hematuria, and a papillary tumor in the prostatic urethra that was diagnosed as ductal carcinoma of the prostate following transurethral resection. Genetic analysis found an APC mutation with loss of heterozygosity. Immunostaining revealed focal nuclear translocation of β-catenin. APC mutations associated with loss of β-catenin degradation in the Wnt signaling pathway and result in over accumulation of β-catenin are thought to increase mortality. In this patient, β-catenin migrated into tumor cell nuclei.ConclusionTo the best of our knowledge, this is the first report of ductal carcinoma of the prostate with an APC mutation in Japan. The development of a therapeutic Wnt inhibitor is discussed.

Abstract P133: Epigenome-Wide Association Study of Moderate-Vigorous Physical Activity in Adult African Americans Identifies Loci Near HCCA2

Regular moderate-vigorous physical activity (MVPA) reduces the risk of cardiovascular and other chronic diseases, among other important benefits at all life stages. It is hypothesized that physical activity may alter disease risk via epigenetic modifications, including potentially long-standing changes in DNA methylation as previous research has shown epigenetic changes following exercise interventions. Most existing reports examine global methylation or study acute exercise effects on DNA methylation. To our knowledge, there are no published epigenome-wide association studies (EWAS) of habitual MVPA. In this analysis, we tested associations between leisure time MVPA and genome-wide variation in CpG methylation, an epigenetic mark, in 2,601 African American participants (1,663 women; mean age 56.6 years) in the Atherosclerosis Risk in Communities (ARIC) study. The Illumina HM450K Bead Chip was used to measure methylation in 471,035 CpG sites in stored frozen leukocyte samples, from visit 2 (1990-1992) or 3 (1993-1995). Linear regression models tested the cross-sectional association of DNA methylation M-value with self-reported leisure time MVPA at the visit of sample collection, modeled as minutes of MVPA per week and by category based on the AHA guidelines for physical activity in adults (none, less than 150, or at least 150 minutes MVPA per week), adjusting for age, sex, body mass index, education, alcohol use in grams per week, smoking status, cancer status, white blood cell count, imputed cell-type proportions using the Houseman method, and batch effects with the top 30 HM450K built-in nonnegative control probe principal components. Three CpGs, cg08269485, cg20272155, and cg08966208, upstream of the cathepsin D encoding gene, CTSD, were observed to be significantly inversely associated (q<0.05, FDR) with MVPA minutes/week. This is a strongly imprinted genomic region (chr11p15.5) and the region has also been reported to include DNA methylation variants that changed in response to an exercise training intervention. Additionally, 163 CpGs that we identified in the literature to be associated with habitual MVPA were also tested using the same models. One CpG, cg07863043, upstream of the adenomatosis polyposis coli gene, APC, in the 5q22.2 genomic region, was observed to be significantly positively associated with achieving at least 150 minutes of MVPA per week compared to none (q=0.0001, FDR). APC encodes a tumor suppressor protein that is an antagonist of the Wnt signaling pathway, and is involved in carcinogenesis and embryonic development. Replication in other populations is ongoing to confirm these findings as well as to identify additional physical activity-related DNA methylation variants.

Characterization of Aneuploid Populations with Trisomy 7 and 20 Derived from Diploid Human Colonic Epithelial Cells

Chromosomal instability leading to aneuploidy occurs in most sporadic colorectal cancers (CRCs) and is believed to be an early driving force in disease progression. Despite this observation, the cellular advantages conferred by these cytogenetic alterations are poorly understood. Here, we provide evidence that serum-free passage of originally diploid, immortalized human colonic epithelial cells (HCECs) gave rise to the acquisition of trisomy 7 (+7), an aneuploidy detected in more than 40% of colorectal adenomas. These cells remain diploid under long-term growth in 2% serum conditions. Analysis by GTG banding and fluorescent in situ hybridization detected no rare preexisting +7 cell in the original population, suggesting a conversion of diploid cells to an aneuploid state. The acquisition of +7 also precedes loss or truncation of the adenomatosis polyposis coli gene as both diploid and +7 cells express full-length, functional protein. Coculturing of fluorescent-labeled cells demonstrate that +7 HCECs have a growth advantage over diploid cells in serum-free conditions. Defects in cell migration and aberrant regulation of the epidermal growth factor receptor, located on chromosome 7p, are also detected in +7 HCECs. Interestingly, knockdown of TP53 and expression of K-RasV12 in +7 HCECs resulted in the emergence of trisomy 20, another nonrandom aneuploidy observed in ∼85% of CRC. In summary, we describe isogenic colonic epithelial cells that represent cytogenetic changes occurring frequently in sporadic CRC. The emergence and characterization of trisomy 7 and 20 demonstrate that these HCECs may serve as unique human cell-based models to examine the effects of chromosomal instability in CRC progression.

Aberrant promoter CpG island hypermethylation of the adenomatosis polyposis coli gene can serve as a good prognostic factor by affecting lymph node metastasis in squamous cell carcinoma of the esophagus

There has been no clear evidence demonstrating whether DNA hypermethylation can affect the prognosis of esophageal cancer. We collected tissue from 50 cases of squamous cell carcinoma of the esophagus and tested them for DNA hypermethylation using methylation-specific polymerase chain reaction. CpG island hypermethylations were observed in 10% for p16, 34% for RARbetaP2, 46% for adenomatosis polyposis coli (APC), 14% for RASSF1A, 84% for FHIT, and 8% for hMLH1. APC promoter hypermethylation was frequently found in patients without lymph node metastasis compared with those with lymph node metastasis (62.5% : 30.8%, P = 0.025). The number of metastatic lymph nodes were lower in patients with APC promoter hypermethylation (0.87 +/- 0.30 : 3.07 +/- 0.72, P = 0.008). Excluding operative mortalities and incomplete resections, 42 patients were analyzed for long-term outcome. During the mean follow-up period of 35 months, 17 developed recurrence and 14 died of cancer. Ten patients died of other causes. In univariable analysis, unmethylation of APC (P = 0.0015) and FHIT (P = 0.0044), as well as presence of lymph node metastasis (P = 0.0038), were risk factors for recurrence. In multivariable analysis, lymph nodes metastasis (P = 0.050) and unmethylation of APC promoter (P = 0.023) remained as significant risk factors. In conclusion, promoter hypermethylation of the APC gene is related to a lower number of metastatic lymph nodes and to superior prognosis in terms of recurrence, which suggests it might be involved in the process of lymph node metastasis in esophageal cancer.

Somatic APC Inactivation Mechanisms in Sporadic Colorectal Cancer Cases in Hungary

The role of germline inactivation of the adenomatosis polyposis coli (APC) gene in hereditary colorectal cancer is well known, being the most important cause of familial adenomatosus polyposis (FAP) syndrome. Hereditary cases with germline mutations, however, account only for 5-10% of colorectal cancers. The somatic inactivation of this gene has also been observed in sporadic cases. In order to examine the inactivation mechanisms of the APC gene we screened 70 sporadic colorectal cancer cases (27 rectal, 43 intestinal) of different stages for promoter hypermethylation, allelic imbalance (AI) and somatic mutations. The presence of promoter hypermethylation was observed in 21 cases (30%). Fifteen of the examined tumors (21%) showed AI, and also 15 tumors (21%) carried at least one somatic mutation. Thirteen of the detected alterations were novel variations: seven frameshifts, four missense mutations and two polymorphisms. Biallelic inactivation was found in 15 patients (21%). These results suggest that the inactivation of the APC gene is very common in sporadic colorectal cancer, and the main inactivation mechanism of the APC gene is promoter hypermethylation. Allelic imbalance has the same frequency as mutations, and mutations in the APC gene are more common in the early stages and in tumors located in the rectum.

Phenotype-genotype correlations in an extended family with adenomatosis coli and an unusual APC gene mutation.

Genotype-phenotype correlations in familial adenomatous polyposis are only partially understood and, in particular, little is known about the biomolecular characteristics of desmoid tumors, which are one of the most serious and frequent manifestations of familial adenomatous polyposis. In the present study, we describe a family with familial adenomatous polyposis, with peculiar clinical characteristics (i.e., frequency and severity of desmoid neoplasms) associated with an unusual mutation of the adenomatosis polyposis coli gene. If confirmed by other investigations, these findings might help to understand the biologic mechanisms by which specific adenomatosis polyposis coli mutations predispose to desmoid tumors. The family with familial adenomatous polyposis, living in southern Italy, was studied from 1985 to the end of 1999; at this date, 15 individuals have been affected by histologically verified familial adenomatous polyposis, 11 of whom had desmoid tumors. A total of 19 family members were studied for adenomatosis polyposis coli gene mutations; 13 of them tested positive and 6 negative. The analytical procedure-previously described-consisted of the extraction of peripheral blood cell DNA, amplification of exon 15 by polymerase chain reaction, single-strand conformation polymorphism analysis, and direct sequencing of the DNA fragment containing the mutation. The main clinical features of the family were 1) a high frequency of desmoid tumors and, consequently, a high penetrance of the desmoid trait in all branches of the family and in 11 (73.3 percent) of 15 affected individuals and 2) severity of desmoids in at least 4 family members, 2 of whom died for causes related to the presence of these tumors. The molecular basis of the disease was an uncommon mutation of the adenomatosis polyposis coli gene, consisting of a large deletion of 310 base pairs at codon 1,464, with duplication of the breakpoint (4,394ins15del310), leading to a stop codon at position 1,575. The present study shows that a truncating mutation in the adenomatosis polyposis coli gene at the beginning of the region frequently associated with desmoids induced a familial adenomatous polyposis phenotype featured by a high penetrance of the desmoid trait, with severe disease in several affected members of both sexes. The study may help to understand the biologic mechanisms of genotype-phenotype correlations in adenomatosis coli.

Novel Germline APC Mutations in Swedish Patients with Familial Adenomatous Polyposis and Gardner Syndrome

Background: Familial adenomatous polyposis (FAP) is a familial cancer syndrome in which affected individuals develop multiple adenomatous polyps and are thereby at greatly increased risk of developing colorectal cancer. Gardner syndrome is a variant of FAP, in which the patients also develop extraintestinal tumors, in particular osteomas and desmoid tumors. An attenuated form of the disease (AFAP) is associated with fewer polyps, but still a high risk for colorectal cancer. Germline mutations in the adenomatosis polyposis coli (APC) gene cause FAP and Gardner syndrome and have recently been associated also with the development of AFAP. Methods: We have analysed the entire APC gene for germline mutations in 7 patients with FAP and in 6 patients with suspected AFAP. Mutation screening was performed by direct sequencing of exons 1-14 and using the protein truncation test for analysis of exon 15. Results: Novel disease-causing germline mutations, all of which resulted in truncation of the APC protein, were identified in 6 of the 7 patients with FAP or Gardner syndrome. No APC mutation was detected in any of the 6 patients with suspected AFAP. Conclusions: This study reports novel FAP- and Gardner syndrome-causing mutations in the APC gene. The lack of APC mutations in patients with multiple polyps at young age indicates that other genetic defects may cause this phenotype.

β-Catenin Regulates the Expression of the Matrix Metalloproteinase-7 in Human Colorectal Cancer

Most colorectal cancers have loss of function mutations in the adenomatosis polyposis coli (APC) tumor suppressor gene. This leads to accumulation of beta-catenin, which together with the DNA binding protein TCF-4 functions as a transcriptional activator. Recently defined target genes are c-myc and cyclin D1, linking the APC gene defect to the capacity for autonomous proliferation of colon tumors. Here we report the identification of the matrix metalloproteinase MMP-7 as another target gene of beta-catenin/TCF-4. MMP-7 is overexpressed in 80% of human colorectal cancers and known to be an important factor for early tumor growth, with a potential function also for later progression steps, like invasion and metastasis. Our results explain the high percentage of MMP-7 overexpression in colon tumors. Moreover they indicate that defects in the APC tumor suppressor gene may also have an influence on later steps of colon tumor progression.

Alleles of APC modulate the frequency and classes of mutations that lead to colon polyps.

Most inherited mutant alleles of the adenomatosis polyposis coli gene (APC) cause the appearance of large numbers of colon polyps, the familial polyposis syndrome. (These mutant alleles are designated APCp alleles.) A subset of APC mutations, the attenuated or APC(AP) alleles, predispose to only a few colon polyps. This leads to the hypothesis that if mutation of the inherited normal allele is rate limiting in polyp development, the increased number of polyps associated with the APCp allele indicates that the frequency of mutations that can lead to polyp formation is higher among APCp carriers than among APC(AP) carriers. We have previously suggested that the APC protein might modulate the frequency of mutations, such as loss of heterozygosity (LOH), necessary for colon polyp formation. We thus reasoned that tumours from patients who carry an APC(AP) allele might show a reduced frequency of LOH compared with tumours from patients who carry an APCp allele. Loss of AAPC mutant alleles is designated as LOH(AP). Screening of tumours from APC(AP) carriers revealed a reduction of LOH compared with that of an unselected group of polyposis patients. In fact, no loss of the inherited APC(N) allele was observed, although sequencing showed that the inherited APC(N) allele had frequently undergone point mutations and small deletions in the tumours. A low frequency loss of the inherited APC(AP) allele was seen. These findings support the suggestion that the APC(AP) allele has residual gene activity and that this activity modulates the spectrum and frequency of mutations that lead to adenoma formation.

Familial adenomatous polyposis: a submicroscopic deletion at the APC locus in a family with mentally normal patients.

Cytogenetically visible deletions that include the adenomatosis polyposis coli (APC) locus have repeatedly been reported in mentally handicapped polyposis patients. We report on a family with a submicroscopic deletion of about 200 kb including more than the 3' half of the APC gene and the adjacent DP1 gene. The deletion was detected by linkage analysis with flanking and intragenic markers and proven by in situ hybridisation with intragenic cosmid clones. All the familial adenomatous polyposis (FAP) patients and persons at risk in the family show normal behaviour and intelligence. Thus, it is conceivable that at least some of the FAP patients in whom mutations could not be identified by routine methods may have large but submicroscopic deletions.