Clinicopathologic and Molecular Characteristics of Familial Adenomatous Polyposis-associated Traditional Serrated Adenoma.

Colorectal carcinogenesis in familial adenomatous polyposis (FAP) follows a conventional adenoma-carcinoma sequence. However, previous studies have also reported the occurrence of traditional serrated adenomas (TSAs) in patients with FAP. In the present study, we analyzed the clinicopathologic and molecular features of 37 TSAs from 21 FAP patients.

Clinicopathological and molecular correlations in traditional serrated adenoma.

Background: Traditional serrated adenoma (TSA) is the least common type of colorectal serrated polyp, which exhibits considerable morphological and molecular diversity.

Methods: We examined the spectra of alterations in MAPK and WNT pathway genes and their relationship with clinicopathological features in 128 TSAs.

Results: Sequencing analyses identified BRAF V600E, BRAF non-V600E, KRAS, and NRAS mutations in 77, 3, 45, and 1 lesion, respectively.

Recurrent YAP1-MAML2 and YAP1-NUTM1 fusions in poroma and porocarcinoma.

Poroma is a benign skin tumor exhibiting terminal sweat gland duct differentiation. The present study aimed to explore the potential role of gene fusions in the tumorigenesis of poromas. RNA sequencing and reverse transcription PCR identified highly recurrent YAP1-MAML2 and YAP1-NUTM1 fusions in poromas (92/104 lesions, 88.

EIF3E-RSPO2 and PIEZO1-RSPO2 fusions in colorectal traditional serrated adenoma.

Aims: Traditional serrated adenoma (TSA) is an uncommon type of colorectal serrated polyp. RSPO fusions, which potentiate WNT signalling, are common and characteristic genetic alterations in TSA. The aim of this study was to further characterise the prevalence and variation of RSPO fusions in TSA.

RHOA mutations and CLDN18-ARHGAP fusions in intestinal-type adenocarcinoma with anastomosing glands of the stomach.

A subtype of intestinal-type adenocarcinoma of the stomach, characterized by low-grade cytological atypia and anastomosing glands, has been described in several reports under different names. One of the remarkable features of these lesions, herein referred to as intestinal-type adenocarcinoma with anastomosing glands, is the frequent association of poorly differentiated adenocarcinoma components. Here we analyzed 44 intestinal-type adenocarcinomas with anastomosing glands focusing on the molecular abnormalities that are common in diffuse-type gastric cancers.

Acquisition of WNT Pathway Gene Alterations Coincides With the Transition From Precursor Polyps to Traditional Serrated Adenomas.

Colorectal traditional serrated adenomas (TSAs) are often associated with precursor polyps, including hyperplastic polyps and sessile serrated adenoma/polyps. To elucidate the molecular mechanisms involved in the progression from precursor polyps to TSAs, the present study analyzed 15 precursor polyp-associated TSAs harboring WNT pathway gene mutations. Laser microdissection-based sequencing analysis showed that BRAF or KRAS mutations were shared between TSA and precursor polyps in all lesions.

Reappraisal of the genetic heterogeneity of sessile serrated adenoma/polyp.

Aims: Sessile serrated adenoma/polyp (SSA/P) is regarded as a genetically homogeneous entity, with most lesions harbouring the BRAF V600E mutation. The present study aimed to reappraise the genetic heterogeneity of SSA/Ps and its clinicopathological significance.

Methods And Results: We performed next-generation sequencing of 272 SSA/Ps without dysplasia and evaluated morphological and molecular features associated with the respective genotypes.

Superficially serrated adenoma: a proposal for a novel subtype of colorectal serrated lesion.

We describe a series of colorectal polyps characterized by mixed adenomatous and serrated features, herein referred to as superficially serrated adenomas. Twenty superficially serrated adenomas were obtained from 11 female and 9 male patients aged 62-87 years. Most lesions endoscopically appeared as small sessile polyps, but larger lesions were plaque-like (2-20 mm; median, 5 mm).

Mismatch repair deficiency commonly precedes adenoma formation in Lynch Syndrome-Associated colorectal tumorigenesis.

Lynch syndrome is a cancer predisposition syndrome caused by germline mutations in mismatch repair (MMR) genes. MMR deficiency is a ubiquitous feature of Lynch syndrome-associated colorectal adenocarcinomas; however, it remains unclear when the MMR-deficient phenotype is acquired during tumorigenesis. To probe this issue, the present study examined genetic alterations and MMR statuses in Lynch syndrome-associated colorectal adenomas and adenocarcinomas, in comparison with sporadic adenomas.

Comprehensive characterization of RSPO fusions in colorectal traditional serrated adenomas.

Aims: Traditional serrated adenoma (TSA) is a rare but distinct type of colorectal polyp. Our previous study showed that PTPRK-RSPO3 fusions are frequent and characteristic genetic alterations in TSAs. This study aimed to characterize comprehensively the prevalence and variability of RSPO fusions in colorectal TSAs.

Cytoplasmic MSH2 immunoreactivity in a patient with Lynch syndrome with an EPCAM-MSH2 fusion.

Aims: Immunohistochemistry for mismatch repair (MMR) proteins is being increasingly used to examine MMR status in tumours. The aim of the present article was to report the case of a colon cancer patient with Lynch syndrome who showed unusual cytoplasmic MMR protein localization.

Methods And Results: Histologically, the colon cancer was diagnosed as medullary carcinoma associated with prominent tumour-infiltrating lymphocytes and a Crohn's-like reaction.

TERT promoter mutations are frequent and show association with MED12 mutations in phyllodes tumors of the breast.

Background: Phyllodes tumors are rare fibroepithelial neoplasms of the breast, which carry the potential risk of local recurrence and metastasis. Phyllodes tumors share several histological features with fibroadenomas, and no widely accepted markers for distinguishing these lesions have been identified.

Methods: We analyzed molecular abnormalities related to telomere elongation in tumors, including TERT promoter mutations, as well as loss of expression of ATRX and DAXX, in a total of 104 phyllodes tumors and fibroadenomas.

Familial adenomatous polyposis-associated and sporadic pyloric gland adenomas of the upper gastrointestinal tract share common genetic features.

Aims: Familial adenomatous polyposis (FAP) is a hereditary cancer predisposition syndrome caused by a germline APC mutation. A recent study showed the enrichment of pyloric gland adenomas (PGAs) of the stomach, in addition to fundic gland polyps (FGPs) and foveolar-type adenomas (FAs), in patients with FAP. In the present study, we analysed the genetic alterations in these FAP-associated gastric lesions.

Frequent lack of GNAS mutations in colorectal adenocarcinoma associated with GNAS-mutated villous adenoma.

Colorectal villous adenoma is thought to be associated with a high risk of progression to adenocarcinoma. To better characterize the genetic alterations involved in colorectal carcinogenesis related to villous adenoma, we analyzed mutations in APC, BRAF, KRAS, TP53, and GNAS in 12 colorectal adenocarcinomas associated with villous adenomas. APC, KRAS, and BRAF mutations were identified in five, 11, and one lesion, respectively, and most of these mutations were shared between the villous adenoma and the adenocarcinoma components in the respective lesions, except in one lesion with APC mutations and in two lesions with KRAS mutations.

Lobular endocervical glandular hyperplasia is a neoplastic entity with frequent activating GNAS mutations.

To clarify the significance of GNAS mutations in cervical tumorigenesis, we performed mutational analyses in a total of 154 lesions and in 22 normal tissues of the uterine cervix. Activating GNAS mutations were found in 8 of the 19 lobular endocervical glandular hyperplasias (LEGH; 42%) and 4 of the 79 endocervical-type mucinous adenocarcinomas (5%) but were never seen in the normal endocervical tissue, minimal deviation adenocarcinomas, endometrioid adenocarcinomas, or squamous cell carcinomas. We further examined the presence of human papillomavirus (HPV) DNA and p16 expression to probe the relationship between GNAS mutations and HPV infection in LEGHs and carcinomas.

Frequent GNAS and KRAS mutations in pyloric gland adenoma of the stomach and duodenum.

Gastric and duodenal adenomas exhibit a significant morphological and phenotypical diversity and are classified into intestinal-type, foveolar-type and pyloric gland adenomas. We analysed the mutations in GNAS, KRAS, BRAF and CTNNB1 and the expressions of mismatch repair (MMR) proteins in 80 gastric and 32 duodenal adenomas with histologically distinct subtypes, as well as in 71 gastric adenocarcinomas. Activating GNAS mutations were found in 22 of the 35 pyloric gland adenomas (PGAs; 63%) but in none of the foveolar-type or intestinal-type adenomas or the adenocarcinomas.

Frequent activating GNAS mutations in villous adenoma of the colorectum.

To elucidate the role of GNAS mutations in colorectal tumourigenesis, we performed a mutation analysis in a total of 234 colorectal tumours, including adenomas, serrated lesions and adenocarcinomas. Activating GNAS mutations were found in 20 of the 24 villous adenomas (83%) but were absent in all the other tumours, except for one tubulovillous adenoma (3%) and two adenocarcinomas (3%). KRAS and BRAF mutations were always mutually exclusive.

Expression of SLCO1B3 is associated with intratumoral cholestasis and CTNNB1 mutations in hepatocellular carcinoma.

Recent studies have shown that intratumoral cholestasis is a hallmark of CTNNB1 mutations in hepatocellular carcinomas (HCC). Here, we analyzed the expressions of genes involved in bile acid and bilirubin metabolism and their correlation with the mutational status of CTNNB1 in a series of HCC. The expressions of CYP7A1 and CYP27A1, which encode rate-limiting enzymes in bile acid synthesis, were unaltered or only marginally increased in CTNNB1-mutated HCC compared with those in HCC with wild-type CTNNB1.

Overexpression of α-methylacyl-CoA racemase is associated with CTNNB1 mutations in hepatocellular carcinomas.

Aims: α-Methylacyl-CoA racemase (AMACR) is expressed in the majority of hepatocellular carcinomas (HCCs) at variable levels, but the significance of AMACR overexpression remains elusive. The aim of this study was to investigate the relationship between AMACR expression and the presence of CTNNB1 mutations in HCCs.

Methods And Results: The expression of AMACR and GLUL, an established downstream target of β-catenin was examined in HCCs, by quantitative reverse transcription polymerase chain reaction (PCR), and the expression of their protein products by immunohistochemistry.

Hepatomas with activating Ctnnb1 mutations in 'Ctnnb1-deficient' livers: a tricky aspect of a conditional knockout mouse model.

Conditional knockout mice, based on the Cre-loxP system, are a widely used model for examining organ-specific gene functions. To date, efficient hepatocyte-specific knockout has been reported in many different models, but little attention has been paid to the long-term stability of the recombination efficiency. In the present study, we characterized Alb-Cre;Ctnnb1flox/flox 'hepatocyte-specific Ctnnb1 knockout' mice of different ages to test whether efficient recombination is maintained over time.

Dicer is required for proper liver zonation.

A number of genes and their protein products are expressed within the liver lobules in a region-specific manner and confer heterogeneous metabolic properties to hepatocytes; this phenomenon is known as 'metabolic zonation'. To elucidate the roles of Dicer, an endoribonuclease III type enzyme required for microRNA biogenesis, in the establishment of liver zonation, we examined the distribution of proteins exhibiting pericentral or periportal localization in hepatocyte-specific Dicer1 knockout mouse livers. Immunohistochemistry showed that the localization of pericentral proteins was mostly preserved in Dicer1-deficient livers.

Esophageal melanomas harbor frequent NRAS mutations unlike melanomas of other mucosal sites.

Mucosal melanomas have genetic alterations distinct from those in cutaneous melanomas. For example, NRAS- and BRAF-activating mutations occur frequently in cutaneous melanomas, but not in mucosal melanomas. We examined 16 esophageal melanomas for genetic alterations in NRAS, BRAF, and KIT to determine whether they exhibit genetic features common to melanomas arising from other mucosal sites.

Disruption of Dicer1 induces dysregulated fetal gene expression and promotes hepatocarcinogenesis.

Background & Aims: Growing evidence suggests that microRNAs coordinate various biological processes in the liver. We describe experiments to address the physiologic roles of these new regulators of gene expression in the liver that are as of yet largely undefined.

Methods: We disrupted Dicer, an enzyme essential for the processing of microRNAs, in hepatocytes using a conditional knockout mouse model to elucidate the consequences of loss of microRNAs.