Detection of global hypermethylation in well-differentiated thyroid neoplasms by immunohistochemical (5-methylcytidine) analysis.

PURPOSE: While global hypomethylation of DNA has been found in several malignancies, studies on thyroid tumours have shown controversial results using different techniques. To help resolve this issue, we assessed methylation status using two different techniques in papillary thyroid carcinomas (PTC) and follicular adenomas (FA) and carcinomas (FTC), comparing adjacent non-neoplastic thyroid tissue. METHODS: A series of 15 FA, 18 FTC and 17 PTC were assessed by: (1) measurement of methylation levels of long interspersed nuclear elements (LINE-1) using a combined bisulfite restriction analysis polymerase chain reaction protocol and (2) immunostaining with an anti-5-methylcytidine antibody that detects methylated DNA regardless of the DNA sequence. Immunostaining was scored by image analysis. RESULTS: Methylation levels of LINE-1 in FA, FTC and PTC were not significantly different from adjacent normal tissue. There was no significant difference in methylation levels of LINE-1 between FA, FTC and PTC (p = 0.44). By immunohistochemical staining for methylation, the 5-methylcytidine score was significantly higher in tumours than in normal tissue counterparts, for FA (p < 0.001), FTC (p = 0.04) and PTC (p = 0.02). PTC showed the highest 5-methylcytidine expression amongst all tumours which was significantly different from FTC (p = 0.015), but not FA (p = 0.09). There was no correlation in methylation level between LINE-1 and 5-methylcytidine scores for each group and overall. CONCLUSIONS: Well-differentiated thyroid neoplasms (FA, FTC and PTC) were not found by two independent methods to undergo global hypomethylation as part of an oncogenic sequence from normal tissue to carcinoma. Instead, hypermethylation was detected in all types of tumours, implying that this epigenetic event may contribute to oncogenic development of thyroid neoplasms (both benign and malignant).

Cyclooxygenase-2 overexpression is associated with clinical outcome in biliary atresia.

OBJECTIVE: The purpose of this study was to investigate the association between cyclooxygenase-2 (COX-2) expression and clinical outcome in biliary atresia (BA) patients. METHODS: Six months after surgery, twenty-eight BA patients were divided into three groups according to their liver function tests: group A with satisfactory liver function (n=11), group B with moderate liver dysfunction (n=8), and group C with severe liver dysfunction (n=9). COX-2 expression was determined by immunohistochemistry. Choledochal cysts (n=5) and normal liver samples (n=4) served as controls. RESULTS: Our data have shown that the intrahepatic biliary epithelium in BA specimens expressed COX-2. The mean immunoreactive score of COX-2 in BA patients was significantly higher than that in choledochal cyst and normal liver (4.0+/-0.6, 0.9+/-0.3, and 0.7+/-0.3, respectively, p<0.002). Strong expression of COX-2 was observed in BA patients with severe liver dysfunction. Subgroup analysis showed that the mean COX-2 immunoreactive scores of patients in group A, B, and C were 2.1+/-0.6, 3.6+/-1.1, and 5.9+/-0.9, respectively. The COX-2 immunoreactive score in BA patients with severe liver dysfunction was higher than in patients with satisfactory liver function (p<0.005). CONCLUSION: Increased COX-2 expression of biliary epithelial cells at the time of Kasai operation was associated with an adverse therapeutic outcome in BA, suggesting that COX-2 could play a plausible role in the liver pathology of BA.

Correlation between immunohistochemical and biochemical estrogen receptors in the prognosis of patients with breast cancer.

To evaluate the reliability of immunohistochemical estrogen receptor (ER) in the prognosis of patients with breast cancer, 83 primary tumors from patients were studied. Immunohistochemical analysis (IHA) was performed using antibody ER 1D5 (Dako) together with microwave treatment for antigen retrieval. ER values obtained using the biochemical steroid binding assay (polyethyleneglycol method, PEG) were available for comparison. Of all tumors, ER positivity was detected in 44.6% by IHA and 36.1% by PEG method. The concordance between the two methods was 69%. No significant correlation was found between the ER status determined by both methods and clinical stage, tumor size, lymph node status or age of patient at diagnosis. However, we found that the immunohistochemical ER is a superior predictor of early recurrence in patients with primary breast cancer to biochemical ER. The findings in the present study emphasize the clinical benefit of the immunohistochemical ER assay as a measure for prognosis.