A significant imbalance in mitosis versus apoptosis accelerates the growth rate of sessile serrated adenoma/polyps

Genome-wide analysis of mRNA expression identified the involvement of trefoil factor 1 in the development of sessile serrated lesions

Precursor lesions that progress into colorectal cancer (CRC) could be largely classified into sessile serrated lesions (SSLs), traditional serrated adenoma (TSA), and tubular adenoma (TA). We aimed to determine whether high expression of trefoil factor 1 (TFF1) is closely associated with serrated lesions, particularly SSLs. The samples were divided into the first (12 SSLs, 5 TSAs, and 15 TAs) and second cohorts (15 SSLs, 9 TSAs, and 15 TAs). First, we investigated TFF1 expression in isolated gland samples using array-based and reverse-transcription PCR. Second, we performed immunohistochemical analysis of TFF1 expression in paraffin-embedded tissues obtained from SSL, TSA, TA, and hyperplastic polyp (HP) samples. In addition, we compared TFF1 mRNA levels between SSLs and HPs. TFF1 expression was significantly higher in SSLs than in TSA and TA in both cohorts. Additionally, immunohistochemical staining of TFF1 in the HP, SSL, TSA, and TA samples revealed significant differences in the immunohistochemical scores of TFF1 among the four types of lesions (higher expression in SSLs than in the other three lesions). Finally, there were significant differences in TFF1 mRNA expression levels between SSLs and HPs in paraffin-embedded tissues. However, there was considerable overlap in the immunohistochemical scores and expression levels of TFF1 transcripts between SSLs and HPs. The current findings may help elucidate the molecular mechanisms involved in serrated lesion development. In addition, we suggest that despite the limited practical application, upregulation of TFF1 transcripts may help differentiate SSLs from other lesions.

Proliferation, apoptosis and their regulatory protein expression in colorectal adenomas and serrated lesions

BACKGROUND

Adenomas and serrated lesions represent heterogeneous sets of early precursors in the colorectum with varying malignant potential. They are often distinguished by their histopathologic differences, but little is known about potential differences in regulation of epithelial proliferation and apoptosis.

METHODS

We conducted a protein expression analysis using tissue microarrays of 625 colorectal adenomas and 142 serrated lesions to determine potential differences in regulation of epithelial proliferation and apoptosis. We quantitated proliferation with Ki-67; apoptosis with activated caspase-3 (CASP3); up- and down-regulators of proliferation with cyclin D1, p16INK2, and p21Cip1; and apoptosis regulators with BAX, BCL2, and survivin. Linear mixed effects models and circos diagrams were used to determine relationships among expression and lesion characteristics.

RESULTS

Adenomas had a significantly higher CASP-3 labeling index (LI) than serrated lesions, resulting in a lower net growth ratio (Ki-67 LI/activated CASP-3 LI, p-value<0.0001). Cyclin D1 LI, p16 LI and p21 LI were lower in adenomas compared to serrated lesions, while expression of both BCL2 and BAX were higher (p <0.001). Among adenomas, cyclin D1 LI and p16 LI levels increased with greater villous component, and the highest BAX expression was detected in adenomas larger than 2 cm (both p<0.0001). Right-sided adenomas had higher CASP3 LI than left colorectal adenomas (p = 0.008). Significant differences in cyclin D1 LI, p21 LI and survivin LI were also observed across histopathologic subtypes of serrated lesions.

CONCLUSIONS

Our findings demonstrate different patterns of regulatory protein expression in adenomas than serrated lesions, especially involving apoptosis. ClinicalTrials.gov Identifier: NCT00272324.

Correlations of morphology and molecular alterations in traditional serrated adenoma

Traditional serrated adenoma was first reported by Longacre and Fenoglio-Presier in 1990. Their initial study described main features of this lesion, but the consensus diagnostic criteria were not widely adopted until recently. Traditional serrated adenoma presents with grossly protuberant configuration and pinecone-like appearance upon endoscopy. Histologically, it is characterized by ectopic crypt formation, slit-like serration, eosinophilic cytoplasm and pencillate nuclei. Although much is now known about the morphology and molecular changes, the mechanisms underlying the morphological alterations are still not fully understood. Furthermore, the origin of traditional serrated adenoma is not completely known. We review recent studies of the traditional serrated adenoma and provide an overview on current understanding of this rare entity.

Serrated Polyps of Colon and Rectum: a Clinicopathologic Review

BACKGROUND

In the past decade, there have been significant changes in the classification and nomenclature of colorectal polyps. Previously, only two groups of lesions were widely recognized, the adenoma and the hyperplastic polyp. Adenomas were considered the only precursor of colorectal cancer, and hyperplastic polyps were considered innocent with no malignant potential. However, recent discoveries about molecular pathways of colorectal cancers have significantly changed our understanding of these neoplasms. Serrated polyps-previously uniformly called hyperplastic polyps-are now known to comprise a heterogeneous family of neoplasms united by their characteristic saw tooth morphology but differing in many important ways, including their malignant potential and molecular profile. This group of neoplasms includes both hyperplastic polyps and the more recently recognized serrated adenomas. Serrated adenomas can be subdivided into the traditional serrated adenoma and the sessile serrated adenoma/polyp. Both of these lesions show characteristic molecular changes, which differ from traditional colorectal adenomatous polyps.

OBJECTIVES

In this review, we will discuss the morphologic features of serrated colorectal lesions, the molecular alterations that characterize them, and their role in colorectal cancer development.

MATERIAL AND METHODS

The English literature regarding the new nomenclature will be reviewed and the key diagnostic points will be recorded.

RESULTS AND DISCUSSION

This large group of polyps has recently been better classified which needs specific attention by pathologists, gastroenterologists and even surgeons.

A case of inflammatory hepatocellular adenoma displaying an unusual histological pattern

Hepatocellular adenoma (HCA) is a rare type of liver tumor. Here, we report a variant case of HCA in a 56-year-old Japanese man which displayed unusual histological features. The patient had undergone surgery for esophageal and gastric cancer 2 years prior. A computed tomography scan performed in the follow-up period detected a single lesion (diameter 1.4 cm) in the right posterior lobe of the liver, leading to a partial hepatectomy. Histologically, the lesion was composed of two different types of cells. The larger cells, which accounted for most of the cells in the tumor, exhibited granular and eosinophilic cytoplasm, large nuclei and apparent nucleoli. These cells, which were designated the common cells, were typical of the HCA. The other cells, which were designated the pyknotic cells, were smaller, possessed an eosinophilic, homogeneous cytoplasm and pyknotic small nuclei, but did not contain nucleoli. Immunohistochemically, the common cells reacted strongly positive for C-reactive protein and serum amyloid A, which is compatible with a diagnosis of inflammatory HCA; in contrast, the pyknotic cells tested negative for these molecules. Since the pyknotic cells tested positive for several markers of apoptosis, they were considered to be apoptotic. In addition, as the common cells demonstrated a higher ki-67 labeling index, the lesion was considered to display upregulated cell kinetics, i.e. increases in both cell growth and death. Although HCA is a rare type of tumor, there have been several reports on HCA variants. The case reported here is that of a new type of HCA variant that demonstrated an unusual histological pattern and upregulated cell kinetics.

Sessile serrated adenomas versus conventional adenomas. Different polyps in different populations?

PURPOSE

The aim of this study was to determine risk factors for the development of sessile serrated adenomas (SSA/Ps) as well as to study differences between groups with SSA/Ps and conventional adenomas (tubular, tubulovillus and villus) in the general population.

METHODS

One hundred patients with normal colonoscopies, 27 patients with 53 SSA/Ps and 69 patients with 156 conventional adenomas were studied, epidemiological data were collected and calculations of body mass index and waist-to-hip ratio were performed prior to endoscopy. A univariate and a multivariate logistic regression analysis were performed using Stata 9.0.

RESULTS

SSA/Ps had a positive association with increasing age (p = 0.01), heavy smoking (≥20 packet years) (p = 0.001) and past history of polyps (p = 0.004) in comparison to normal population. SSA/Ps showed an inverse association with conventional adenomas for diabetes mellitus (p < 0.001) and arterial hypertension (p = 0.001). Meanwhile, female sex was positively associated with SSA/P development in comparison to conventional adenomas (p = 0.031).

CONCLUSIONS

Heavy smoking as a significant risk factor for developing SSA/Ps was confirmed from this study. It also seemed that patients with diabetes mellitus and/or hypertension developed conventional adenomas more frequently than SSA/Ps; on the contrary, females were at higher risk of developing SSA/Ps than conventional adenomas.

Apoptosis and expression of argyrophilic nucleolus organizer regions in epithelial neoplasms of the larynx

Introduction

Occurrence of apoptosis and expression of proliferative markers are powerful tools to establish a prognosis in the follow-up of cancer.

Objective

To evaluate the growth fraction in papillomas and laryngeal squamous cell carcinomas with three degrees of differentiation through apoptosis and the expression of nucleolus organizer regions.

Methods

Retrospective study from which paraffin material was submitted to microtomy and hematoxylin–eosin and silver staining. Stained slides were used to quantify the apoptotic index and the number of nucleolus organizer regions by morphometry.

Results

Apoptosis was significantly more frequent in well differentiated carcinomas and in papillomas, and a higher growth fraction of expressed nucleolus organizer regions and cells that expressed a greater than average number of nucleolus organizer regions were more frequently noted in undifferentiated carcinomas.

Conclusions

Thus, it was possible to verify that a high apoptotic index was associated with a lower chance of tumor differentiation in carcinomas, while a greater number of total nucleolus organizer regions, cells expressing nucleolus organizer regions above average and a higher growth fraction were associated with greater likelihood of abnormal cell proliferation and increased tumor differentiation.

Claudin-1 Expression Is Elevated in Colorectal Cancer Precursor Lesions Harboring the BRAF V600E Mutation

BACKGROUND: Sessile serrated adenomas/polyps (SSA/P) are now recognised precursors of colorectal cancer (CRC) including cancers harbouring somatic BRAF (V600E) mutations. While the morphological diagnostic criteria of SSA/P have been established, distinguishing between small/early SSA/P and microvesicular hyperplastic polyps (MVHP) is challenging and may not be possible in routine practice. METHODS: Gene expression profiling of MVHP (n=5, all BRAF V600E wild-type) and SSA/P (n=5, all BRAF V600E mutant) samples was performed. Quantitative reverse transcription–polymerase chain reaction (qRT-PCR) and immunohistochemical analysis was performed to verify the expression of claudin 1 (CLDN1) in MVHP and SSA/P. RESULTS: Gene expression profiling studies conducted between MVHP and SSA/P identified CLDN1 as the most statistically significant differentially expressed gene (p<0.05). Validation with qRT-PCR confirmed an up-regulation of CLDN1 in BRAF V600E mutant polyps regardless of polyp type (p<0.0005). Immunohistochemical analysis of CLDN1 expression in BRAF V600E mutant SSA/Ps (n=53) and MVHPs (n=111) and BRAF wild-type MVHPs (n=58), demonstrated a strong correlation between CLDN1 expression and the BRAF V600E mutation in both SSA/P and MVHP samples when compared to wild-type polyps (p<0.0001). CONCLUSION: This study demonstrates an up regulation of CLDN1 protein in serrated colorectal polyps including MVHP harbouring the BRAF V600E mutation. Our results demonstrated an apparent heterogeneity on the molecular level within the MVHP group and suggest that MVHP with somatic BRAF V600E mutation and up-regulated expression of CLDN1 are closely related to SSA/P and may in fact represent a continuous spectrum of the same neoplastic process within the serrated pathway of colorectal carcinogenesis.