Expression of Ki-67 and cytokeratin 20 in hyperplastic polyps of the colorectum

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). Eighteen lesions (90%) were located in the sigmoid colon or rectum. They consisted primarily of straight, adenomatous glands but showed serration confined to the superficial layer. Immunohistochemistry revealed CK20 expression in the upper layer. Proliferating cells, determined by their expression of Ki-67, were localized to the middle to bottom layers. Genetic analyses identified KRAS mutations in 19 lesions and a BRAF mutation in one lesion. Furthermore, RSPO fusions and/or overexpression were observed in 18 lesions and truncating APC mutations were observed in the two remaining lesions. Consistent with the presence of WNT pathway gene alterations, all superficially serrated adenomas showed focal or diffuse nuclear β-catenin accumulation. Since concurrent KRAS mutations and RSPO fusions are reportedly common in traditional serrated adenomas, we reviewed 129 traditional serrated adenomas and found 15 lesions (12%) that were associated with superficially serrated adenoma components. Remarkably, all but one superficially serrated adenoma-associated traditional serrated adenoma exhibited concurrent KRAS mutations and RSPO fusions/overexpression. The present study suggests that superficially serrated adenoma is a morphologically and molecularly distinct type of colorectal serrated polyp that is histogenetically related to traditional serrated adenoma.

Pathologic Features of Colorectal Inflammatory Polyps in Miniature Dachshunds

The histopathologic characteristics of colorectal inflammatory polyps that formed in Miniature Dachshunds were compared with those of other colorectal proliferative lesions, including adenomas and adenocarcinomas. Fifty-three colorectal polypoid lesions were histopathologically classified into inflammatory polyps (26 cases), adenoma (18 cases), and adenocarcinoma (9 cases). All 26 dogs that were diagnosed with inflammatory polyps were Miniature Dachshunds, indicating that colorectal inflammatory polyps exhibit a marked predilection for this breed. The inflammatory polyps had complex histopathologic features and were classified into 3 stages based on their epithelial composition. In early stage (stage 1), the polyps tended to exhibit a thickened mucosa containing hyperplastic goblet cells, dilated crypts filled with a large amount of mucus, and mild lymphocyte and macrophage infiltration. In later stages (stages 2 and 3), more severe neutrophil infiltration, interstitial mucus accumulation, granulation tissue, and occasional osteoid tissue were seen. Also, a few small foci of dysplastic epithelial cells were detected. The hyperplastic goblet cells, which were a major component of the epithelium of the inflammatory polyps, were positive for cytokeratin 20 (CK20), while the dysplastic epithelial cells found in inflammatory polyps (stage 3) and the tumor cells of the adenomas and adenocarcinomas were negative for CK20. These CK20-negative epithelial cells exhibited cytoplasmic and nuclear immunoreactivity for beta-catenin. In addition, the epithelial cells in the inflammatory polyps demonstrated significantly higher cyclooxygenase 2 and fibroblast growth factor 2 expression than did those of the adenomas and adenocarcinomas, suggesting that the arachidonate cascade is involved in the development of colorectal inflammatory polyps in miniature dachshunds.

Tissue-specific patterns of gene expression in the epithelium and stroma of normal colon in healthy individuals in an aspirin intervention trial

Background

Regular aspirin use reduces colon adenoma and carcinoma incidence. UDP-glucuronosyltransferases (UGT) are involved in aspirin metabolism and clearance, and variant alleles in UGT1A6 have been shown to alter salicylic acid metabolism and risk of colon neoplasia.

Methods

In a randomized, cross-over, placebo-controlled trial of 44 healthy men and women, homozygous for UGT1A6*1 or UGT1A6*2, we explored differences between global epithelial and stromal expression, using Affymetrix U133 + 2.0 microarrays and tested effects of 60-day aspirin supplementation (325 mg/d) on epithelial and stromal gene expression and colon prostaglandin E2 (PGE2) levels.

Results

No statistically significant differences in gene expression were observed in response to aspirin or UGT1A6 genotype, but tissue PGE2 levels were lower with aspirin compared to placebo (p <0.001). Transcripts differentially expressed between epithelium and stroma (N = 4916, P <0.01, false discovery rate <0.001), included a high proportion of genes involved in cell signaling, cellular movement, and cancer. Genes preferentially expressed in epithelium were involved in drug and xenobiotic metabolism, fatty acid and lipid metabolism, apoptosis signaling, and ion transport. Genes preferentially expressed in stroma included those involved in inflammation, cellular adhesion, and extracellular matrix production. Wnt-Tcf4 pathway genes were expressed in both epithelium and stroma but differed by subcellular location.

Conclusions

These results suggest that, in healthy individuals, subtle effects of aspirin on gene expression in normal colon tissue are likely overwhelmed by inter-individual variability in microarray analyses. Differential expression of critical genes between colonic epithelium and stroma suggest that these tissue types need to be considered separately.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-015-0161-6) contains supplementary material, which is available to authorized users.

[Serrated lesions of the large bowel]

The 2010 WHO classification identifies a new group of pretumor lesions of the large bowel--serrated masses, which includes hyperplastic polyps (HPs), sessile serrated adenomas/polyps (SSA/P), and traditional serrated adenomas (TSA). Serrated masses are a heterogeneous group characterized by serrated gland lumens and, in most cases, without dysplasia. An enlarged proliferative zone, elongated crypts, and no cytological atypia in addition to a serrated lumen are typical of HPs. SSA/P is characterized by the migration of the proliferative zone to the crypt walls, giving rise to specific architectural disorders, such as expanded and horizontally growing basal gland segments along the lamina muscularis mucosae. TSA is typified by short ectopic crypts that cannot reach the lamina muscularis and by epithelial eosinophilic changes. SSA/P and TSA have peculiar molecular genetic profiles and proven malignant potential.

One-step preservation of phosphoproteins and tissue morphology at room temperature for diagnostic and research specimens

Background

There is an urgent need to measure phosphorylated cell signaling proteins in cancer tissue for the individualization of molecular targeted kinase inhibitor therapy. However, phosphoproteins fluctuate rapidly following tissue procurement. Snap-freezing preserves phosphoproteins, but is unavailable in most clinics and compromises diagnostic morphology. Formalin fixation preserves tissue histomorphology, but penetrates tissue slowly, and is unsuitable for stabilizing phosphoproteins. We originated and evaluated a novel one-step biomarker and histology preservative (BHP) chemistry that stabilizes signaling protein phosphorylation and retains formalin-like tissue histomorphology with equivalent immunohistochemistry in a single paraffin block.

Results

Total protein yield extracted from BHP-fixed, routine paraffin-embedded mouse liver was 100% compared to snap-frozen tissue. The abundance of 14 phosphorylated proteins was found to be stable over extended fixation times in BHP fixed paraffin embedded human colon mucosa. Compared to matched snap-frozen tissue, 8 phosphoproteins were equally preserved in mouse liver, while AMPKβ1 Ser108 was slightly elevated after BHP fixation. More than 25 tissues from mouse, cat and human specimens were evaluated for preservation of histomorphology. Selected tissues were evaluated in a multi-site, independent pathology review. Tissue fixed with BHP showed equivalent preservation of cytoplasmic and membrane cytomorphology, with significantly better nuclear chromatin preservation by BHP compared to formalin. Immunohistochemical staining of 13 non-phosphorylated proteins, including estrogen receptor alpha, progesterone receptor, Ki-67 and Her2, was equal to or stronger in BHP compared to formalin. BHP demonstrated significantly improved immunohistochemical detection of phosphorylated proteins ERK Thr202/Tyr204, GSK3-α/β Ser21/Ser9, p38-MAPK Thr180/Tyr182, eIF4G Ser1108 and Acetyl-CoA Carboxylase Ser79.

Conclusion

In a single paraffin block BHP preserved the phosphorylation state of several signaling proteins at a level comparable to snap-freezing, while maintaining the full diagnostic immunohistochemical and histomorphologic detail of formalin fixation. This new tissue fixative has the potential to greatly facilitate personalized medicine, biobanking, and phospho-proteomic research.

Hyperplastic polyps are innocuous lesions in hereditary nonpolyposis colorectal cancers

Aims. To compare methylation profiles, protein expression, and microsatellite instability (MSI) of sporadic, HNPCC, and familial hyperplastic polyps (HPs). Methods. Methylation-specific PCR (MSP) and pyrosequencing assessed p16, MGMT, hMLH-1, MINT 1, and MINT 31 methylation. IHC (Immunohistochemistry) assessed Ki67, CK20, hMLH-1, hMSH-2, and hMSH-6 protein expression. MSI analysis was performed on those polyps with adequate DNA remaining. Results. 124 HPs were identified 78 sporadic, 21 HNPCC, 25 familial, and the HNPCC group demonstrated no significant differences in overall methylation (P = .186 Chi²). The familial group demonstrated significantly less over all methylation levels (P = .004 Chi²). Conclusions. HPs that occur in HNPCC have no more worrying features at a molecular level than those patients with HPs in a sporadic setting.

Cellular quiescence in mammary stem cells and breast tumor stem cells: got testable hypotheses?

Cellular quiescence is a state of reversible cell cycle arrest and has more recently been shown to be a blockade to differentiation and to correlate with resistance to cancer chemotherapeutics and other xenobiotics; features that are common to adult stem cells and possibly tumor stem cells. The biphasic kinetics of mammary regeneration, coupled to its cyclic endocrine control suggest that mammary stem cells most likely divide during a narrow window of the regenerative cycle and return to a state of quiescence. This would enable them to retain their proliferative capacity, resist differentiation signals and preserve their prolonged life span. There is accumulating evidence that mammary stem cells and other adult stem cells utilize quiescence for this purpose, however the degree to which tumor stem cells do so is largely unknown. The retained proliferative capacity of mammary stem cells likely enables them to accumulate and harbor mutations that lead to breast cancer initiation. However it is currently unclear if these causative lesions lead to defective or deranged quiescence in mammary stem cells. Evidence of such effects could potentially lead to the development of diagnostic systems that monitor mammary stem cell quiescence or activation. Such systems may be useful for the evaluation of patients who are at significant risk of breast cancer. Additionally quiescence has been postulated to contribute to therapeutic resistance and tumor recurrence. This review aims to evaluate what is known about the mechanisms governing cellular quiescence and the role of tumor stem cell quiescence in breast cancer recurrence.

HNPCC-associated synchronous early-stage signet-ring cell carcinomas of colonic origin. A comparative morphological and immunohistochemical study of an intramucosal and a submucosal example

Signet-ring cell carcinoma (SRCC) developing in the colorectum (CR) is infrequently identified at an early stage (no deeper than submucosa). Most such examples involve the submucosa. Merely 13 cases of intramucosal CR SRCC are at hand. We recently had the opportunity to study a specimen with two synchronous early-stage SRCC, developed in a 65-year-old hereditary nonpolyposis colorectal cancer male patient with a known disease-causing mutation in MLH1. A right hemicolectomy specimen comprised a 15-mm intramucosal cecal lesion, featuring zones of conventional tubular adenoma and intraepithelial SRCC as well as tumor cells multifocally permeating the lamina propria and a 12-mm submucosally expanding SRCC of the ascending colon. The intramucosal and intraepithelial as well as stromal lesional cells displayed a normal membranous expression of beta-catenin and E-cadherin; submucosally infiltrating cells featured alterations in this complex with loss of membranous expression of both proteins and a shift with nuclear accumulation of beta-catenin, suggesting a disruption of the Wingless signaling pathway taking place at the transition from the intramucosal to the submucosal level.

Colonic chicken-skin mucosa in children with polyps is not a preneoplastic lesion

Colonic polyps are common both in adults and children; however, the malignant potential varies according to the type of polyp. Most childhood polyps are solitary juvenile polyps, which have negligible malignant potential. Chicken-skin mucosa (CSM) is an endoscopic finding initially described associated with adenomatous polyps and adenocarcinoma, suggesting a preneoplastic lesion. Subsequently, CSM was described in association with juvenile polyps, suggesting that this mucosal finding is not a precursor to dysplasia. To determine whether CSM represents a preneoplastic lesion, we studied endoscopic colonic mucosal biopsies for markers of cell replication (Ki-67) and malignant transformation (p53) in mucosal biopsies of CSM, normal colonic tissue, tubular adenomas, and adenocarcinomas. Samples were subjected to immunostaining for the presence of Ki-67 and p53. The degree of Ki-67-positive staining cells was similar for CSM and normal colonic tissue, whereas there was significantly increased staining for both tubular adenomas and adenocarcinomas. There was no evidence of p53 staining in CSM and normal colonic mucosa, whereas there was varying degrees of staining in tubular adenomas and adenocarcinomas. The association of CSM with benign juvenile polyps and the absence of histologic markers for increased replication and malignant transformation support the notion that this endoscopic finding is not preneoplastic. Rather, CSM arises in proximity to polyps of all histologic types because of local mucosal damage.

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Detection of occult tumour cells in lymph nodes of colorectal cancer patients using real-time quantitative RT-PCR for CEA and CK20 mRNAS

The purpose of our study was to develop specific, sensitive, objective assays for early detection of disseminated tumour cells in patients with colorectal cancer (CRC). Carcinoembryonic antigen (CEA) and cytokeratin 20 (CK20) were chosen as markers because they are selectively expressed in epithelial cells with maintained expression in CRC. Real-time quantitative RT-PCR assays with RNA copy standards were constructed. Regional lymph nodes were collected from patients with CRC (n = 51) and benign intestinal disease (n = 10). Results were compared to routine histopathology and anti-CEA immunohistochemistry. Lymph node levels of CEA and CK20 mRNA correlated strongly (p < 0.0001, r = 0.8). Lymph nodes from non-CRC patients had <0.01 CEA and <0.001 CK20 mRNA copies/18S rRNA unit. Lymph nodes from 3/6 Dukes' A, 17/26 Dukes' B, 10/10 Dukes' C and 7/9 Dukes' D patients had CEA mRNA levels above cut-off. Corresponding figures for CK20 mRNA were 3/6, 10/26, 9/10 and 5/9, respectively. CEA mRNA levels varied from 0.001 to 100 copies/18S rRNA unit in Dukes' A and B, and 50% of the Dukes' B patients had CEA mRNA levels within the range of Dukes' C patients. Three Dukes' B patients have died from CRC or developed distant metastases. All 3 had high CEA and CK20 mRNA levels. Determination of mRNA was superior to immunohistochemistry in showing CEA expression in lymph nodes. The present qRT-PCR assay for CEA mRNA seems to be a superior tool to identify individuals with disseminated tumour cells. Future extended studies will establish the clinically most relevant cut-off level.