CDK8 expression in 470 colorectal cancers in relation to β‐catenin activation,other molecular alterations and patient survival

Alterations in the Wnt/β‐catenin pathway define a key event in the pathogenesis of colon cancer. We have recently shown that CDK8, the gene encoding a cyclin‐dependent kinase (CDK) component of the Mediator complex, acts as a colon cancer oncogene that is necessary for β‐catenin activity. Here, we tested the hypothesis that colorectal cancers with CDK8 expression have distinct clinical, prognostic and molecular attributes. Among 470 colorectal cancers identified in 2 prospective cohort studies, CDK8 expression was detected in 329 (70%) tumors by immunohistochemistry. Cox proportional hazards model and backward stepwise elimination were used to compute hazard ratio (HR) of deaths according to CDK8 status, initially adjusted for various patient and molecular features, including β‐catenin, p53, p21, p27 (CDK inhibitors), cyclin D1, fatty acid synthase (FASN), cyclooxygenase‐2 (COX‐2), microsatellite instability (MSI), CpG island methylator phenotype (CIMP), LINE‐1 methylation, and mutations in KRAS, BRAF and PIK3CA. CDK8 expression in colorectal cancer was independently associated with β‐catenin activation (p = 0.0002), female gender (p < 0.0001) and FASN overexpression (p = 0.0003). Among colon cancer patients, CDK8 expression significantly increased colon cancer‐specific mortality in both univariate analysis [HR 1.70; 95% confidence interval (CI), 1.03–2.83; p = 0.039] and multivariate analysis (adjusted HR 2.05; 95% CI, 1.18–3.56; p = 0.011) that was adjusted for potential confounders including β‐catenin, COX‐2, FASN, LINE‐1 hypomethylation, CIMP and MSI. CDK8 expression was unrelated with clinical outcome among rectal cancer patients. These data support a potential link between CDK8 and β‐catenin, and suggest that CDK8 may identify a subset of colon cancer patients with a poor prognosis.     

Usefulness of narrow-band imaging endoscopy for diagnosis of Barrett’s esophagus

Background A newly developed endoscope lighting system called a narrow-band imaging system emphasizes certain histological features such as capillary and crypt patterns. The usefulness of NBI for the diagnosis of Barretts esophagus (BE) was evaluated.Methods Eleven patients with previously diagnosed BE were enrolled in this study. Magnifying endoscopy was performed by an experienced endoscopist, using both a conventional system and an NBI system. All images were recorded by video and by a digital still image filing system. Differences in images were evaluated by another experienced endoscopist. The quality of images for the visualization of the esophagogastric junction, capillary vessels, and columnar-lined esophagus (CLE) was judged as: optimal (score of 4), diagnostic (3), suboptimal (2), or nondiagnostic (1).Results In contrast to the low rate of visualization of the esophagogastric junction by conventional endoscopy, visualization of this area endoscopy was better by NBI. Net-like blood vessels were more clearly seen on images obtained by NBI endoscopy. Visualization of the CLE was better by NBI endoscopy than by conventional endoscopy. In contrast to conventional endoscopy, NBI endoscopy captured the optimal view of Barretts epithelium. The relationship between the endoscopic and histopathologic diagnoses was more accurate by NBI endoscopy than by conventional endoscopy.Conclusions Magnifying endoscopy by NBI is more useful than conventional magnifying endoscopy for the diagnosis of BE.     

Chemotherapy-resistant CD7-positive stem cell lymphoma presenting with intra-abdominal mass

We report a case of CD7+ stem cell lymphoma. A 47-year-old man presented with general malaise and lumbago in April 1997. The patient exhibited swollen left cervical lymph-nodes and an intra-abdominal bulky mass. He was referred to us because lymph-node biopsy specimens indicated a diagnosis of diffuse type malignant lymphoma. An abdominal CT scan disclosed large retroperitoneal, para-aortic, and mesenteric root masses. Bone marrow involvement was shown by bone marrow biopsy specimens, though no circulating blasts were detected at presentation. The patient was treated with high-dose CHOP therapy without any benefit. Though ESHAP therapy was performed as salvage chemotherapy, the abdominal masses did not shrink at all. The patient died of tumor progression in November 1997. In the terminal stage, the lymphoma cells emerged in the peripheral blood and thus became available for analysis. The cells expressed CD5, 7, 34, 38, 71, but were negative for CD1, 2, 3, 4, 8, 10, 13, 14, 16, 19, 20, 21, 25, HLA-DR, and EMA. An immunoglobulin heavy chain gene rearrangement band was detected by Southern blot analysis. However, no T cell receptor lambda or beta chain gene rearrangement bands were detected.     

Prognostic significance of AMP-activated protein kinase expression and modifying effect of MAPK3/1 in colorectal cancer

Background:

AMP-activated protein kinase (AMPK, PRKA) has central roles in cellular metabolic sensing and energy balance homeostasis, and interacts with various pathways (e.g., TP53 (p53), FASN, MTOR and MAPK3/1 (ERK)). AMP-activated protein kinase activation is cytotoxic to cancer cells, supporting AMPK as a tumour suppressor and a potential therapeutic target. However, no study has examined its prognostic role in colorectal cancers.

Methods:

Among 718 colon and rectal cancers, phosphorylated AMPK (p-AMPK) and p-MAPK3/1 expression was detected in 409 and 202 tumours, respectively, by immunohistochemistry. Cox proportional hazards model was used to compute mortality hazard ratio (HR), adjusting for clinical and tumoral features, including microsatellite instability, CpG island methylator phenotype, LINE-1 methylation, and KRAS, BRAF and PIK3CA mutations.

Results:

Phosphorylated AMPK expression was not associated with survival among all patients. Notably, prognostic effect of p-AMPK significantly differed by p-MAPK3/1 status (P_interaction=0.0017). Phosphorylated AMPK expression was associated with superior colorectal cancer-specific survival (adjusted HR 0.42; 95% confidence interval (CI), 0.24–0.74) among p-MAPK3/1-positive cases, but not among p-MAPK3/1-negative cases (adjusted HR 1.22; 95% CI: 0.85–1.75).

Conclusion:

Phosphorylated AMPK expression in colorectal cancer is associated with superior prognosis among p-MAPK3/1-positive cases, but not among p-MAPK3/1-negative cases, suggesting a possible interaction between the AMPK and MAPK pathways influencing tumour behaviour.     

IGF2 differentially methylated region hypomethylation in relation to pathological and molecular features of serrated lesions

AIM:To investigate insulin-like growth factor 2(IGF2)differentially methylated region(DMR)0 hypomethylation in relation to clinicopathological and molecular features in colorectal serrated lesions.METHODS:To accurately analyze the association between the histological types and molecular features of each type of serrated lesion,we consecutively collected1386 formalin-fixed paraffin-embedded tissue specimens that comprised all histological types[hyperplastic polyps(HPs,n=121),sessile serrated adenomas(SSAs,n=132),traditional serrated adenomas(TSAs,n=111),non-serrated adenomas(n=195),and colorectal cancers(n=827)].We evaluated the methylation levels of IGF2 DMR0 and long interspersed nucleotide element-1(LINE-1)in HPs(n=115),SSAs(n=120),SSAs with cytological dysplasia(n=10),TSAs(n=91),TSAs with high-grade dysplasia(HGD)(n=15),non-serrated adenomas(n=80),non-serrated adenomas with HGD(n=105),and CRCs(n=794).For the accurate quantification of the relative methylation levels(scale 0%-100%)of IGF2 DMR0 and LINE-1,we used bisulfite pyrosequencing method.Tumor specimens were analyzed for microsatellite instability,KRAS(codons 12 and 13),BRAF(V600E),and PIK3CA(exons 9and 20)mutations;MLH1 and MGMT methylation;and IGF2 expression by immunohistochemistry.RESULTS:The distribution of the IGF2 DMR0 methylation level in 351 serrated lesions and 185 non-serrated adenomas(with or without HGD)was as follows:mean61.7,median 62.5,SD 18.0,range 5.0-99.0,interquartile range 49.5-74.4.The IGF2 DMR0 methylation level was divided into quartiles(Q1≥74.5,Q2 62.6-74.4,Q3 49.6-62.5,Q4≤49.5)for further analysis.With regard to the histological type,the IGF2 DMR0 methylation levels of SSAs(mean±SD,73.1±12.3)were significantly higher than those of HPs(61.9±20.5),TSAs(61.6±19.6),and non-serrated adenomas(59.0±15.8)(P<0.0001).The IGF2 DMR0 methylation level was inversely correlated with the IGF2 expression level(r=-0.21,P=0.0051).IGF2 DMR0 hypomethylation was less frequently detected in SSAs compared with HPs,TSAs,and non-serrated adenomas(P<0.0001).Multivariate logistic regression analysis also showed that IGF2 DMR0 hypomethylation was inversely associated with SSAs(P<0.0001).The methylation levels of IGF2 DMR0 and LINE-1 in TSAs with HGD(50.2±18.7and 55.7±5.4,respectively)were significantly lower than those in TSAs(61.6±19.6 and 58.8±4.7,respectively)(IGF2 DMR0,P=0.038;LINE-1,P=0.024).CONCLUSION:IGF2 DMR0 hypomethylation may be an infrequent epigenetic alteration in the SSA pathway.Hypomethylation of IGF2 DMR0 and LINE-1 may play a role in TSA pathway progression.