Thioredoxin reductase 1 (TrxR) is a homodimeric selenoenzyme catalyzing thioredoxin (Trx) in an NADPHdependent manner. With regard to carcinogenesis, these redox proteins have been implicated in cell proliferation, transformation and anti-apoptosis. In the present study, using a hamster cholangiocarcinoma (ChC) model, we evaluated the immunohistochemical expression pattern of TrxR in precancerous lesions and ChCs as well as in normal bile ducts. The goal of this study was to determine the potential role and importance of TrxR in cholangiocarcinogenesis. For the ChC model, we obtained liver tissue specimens with dysplastic bile ducts prior to the development of ChC 8 weeks after initiation of the experiment and ChC samples at 27 weeks. The immunohistochemical analysis showed diffuse cytoplasmic overexpression of TrxR in the dysplastic bile duct epithelial cells as well as in cholangiocarcinoma; this was comparable to the negative or weakly positive in normal and type 1 hyperplastic bile ducts. However, TrxR appeared to be considerably down-regulated in the ChCs when compared to the higher expression observed in the dysplastic bile ducts. Therefore, these results suggest that TrxR overexpression followed by down-regulation might be an important event in cholangiocarcinogenesis, especially at early stages including the cellular transformation of candidate bile ducts. Further studies are however required to determine whether TrxR may be a potential target molecule for chemoprevention against cholangiocarcinogenesis. In addition, the molecular mechanism as well as the importance of the loss of TrxR in the development of cholangiocarcinoma, following dysplastic transformation of bile duct cells, also remains to be clarified.
Animals ; Bile Duct Neoplasms/*enzymology/pathology ; Bile Ducts/enzymology/pathology ; Cholangiocarcinoma/*enzymology/pathology ; Cricetinae ; Disease Models, Animal ; Immunohistochemistry ; Mesocricetus ; Precancerous Conditions/*enzymology/pathology ; Thioredoxin Reductase (NADPH)/*biosynthesis

BACKGROUND: Helicobacter pylori (H. pylori) has been considered a definitive carcinogen in gastric cancer. Telomerase is activated in gastric cancer and some premalignant gastric lesions, including intestinal metaplasia (IM). In this study, we evaluated the relationships of both H. pylori infection and telomerase activity with endoscopic and histologic features in IM. The effects of H. pylori eradication on endoscopic, histologic and biochemical changes were evaluated. METHODS: Endoscopic biopsies were obtained from 43 patients with IM for rapid urease, histologic and telomerase tests. The endoscopic and histologic features, H. pylori infection and telomerase were assessed. After H. pylori eradication, 15 patients were re-evaluated and compared after 4 months. RESULTS: Thirty-four (79.1%) patients were infected with H. pylori. The incidence of H. pylori infection was borderline correlated to the severity of IM (p=0.076). Telomerase was elevated in eight (18.6%) patients. Telomerase tends to be high in subtype III and endoscopic grade III of IM. After H. pylori eradication, endoscopic extent (p=0.039) and histologic severity (p=0.074) showed improvements, and telomerase decreased significantly (p=0.0001). CONCLUSION: Our data suggest that telomerase is associated with the severity and extent of IM and that H. pylori eradication improves the endoscopic and histologic features in IM, and decreases telomerase activity. H. pylori eradication can be considered one of the methods to prevent gastric cancer in patients with H. pylori-infected IM. Further long-term and large-scaled study will be needed.
Female ; Helicobacter Infections/*enzymology ; *Helicobacter pylori ; Human ; Intestinal Mucosa/enzymology/microbiology/*pathology ; Male ; Metaplasia/enzymology/microbiology ; Middle Aged ; Precancerous Conditions/enzymology/microbiology ; Stomach Neoplasms/*enzymology/microbiology ; Telomerase/*metabolism

Telomerase is highly activated in human immortal cell lines and tumor tissues, whereas it is not activated in primary cell strains and many tumor-adjacent tissues. It is suggested that telomerase activation is one of the critical steps in malignant transformation. In the present study, the telomerase activity was investigated in hepatocellular carcinoma tissues and non-tumor liver tissues from Korean patients with chronic hepatitis and cirrhosis. Eighty two liver tissues (24 chronic hepatitis specimens, 34 cirrhosis specimens, and 24 hepatocellular carcinomas) were obtained from 23 chronic viral hepatitis patients, 19 cirrhosis patients (including 7 liver transplants), and 24 patients with hepatocellular carcinoma, of which the surrounding non-tumor liver tissues were available in 16 patients (1 chronic hepatitis and 15 cirrhosis). As negative controls, 3 normal liver tissues were included. Protein from liver specimens was purified by a detergent lysis method as described elsewhere, and telomerase activity was measured in 2 diluents of each sample (1:1 and 1:100) by a telomeric repeat amplification protocol (TRAP). Telomerase was strongly activated in 79% (19/24) of the hepatocellular carcinomas, while weakly in 8% (2/24) of the chronic hepatitis tissues and in 24% (8/34) of the cirrhosis tissues. All of 3 normal control livers showed no telomerase activation. No relationship could be observed between the enhancement of telomerase activity and tumor nature. None of the chronic heaptitis or cirrhosis patients with mild telomerase activation in the liver have developed hepatocellular carcinoma for at least 2 years of follow-up period. These results suggest that the strong enhancement of telomerase activity may be a critical part of hepatocarcinogenesis, although the exact mechanism of such high activation in hepatocellular carcinoma is not clear. In addition, further study will be necessary to clarify the reason why no telomerase activity detectable by a conventional TRAP can be seen in some hepatocellular carcinoma.
Adult ; Aged ; Carcinoma, Hepatocellular/pathology ; Carcinoma, Hepatocellular/enzymology* ; Cell Transformation, Neoplastic* ; Comparative Study ; Enzyme Activation ; Female ; Hepatitis, Chronic/enzymology ; Human ; Liver Cirrhosis/enzymology ; Liver Neoplasms/pathology ; Liver Neoplasms/enzymology* ; Male ; Middle Age ; Precancerous Conditions/enzymology* ; Telomerase/analysis*

OBJECTIVETo study the level of expression of Caspase-3 protein in precancerous lesions of stomach and its relation to gastric carcinogenesis.

METHODSFormalin-fixed paraffin embedded tissues from 184 cases of gastric mucosa biopsy and surgically removed specimens, including gastric cancer (GC, N = 20), chronic atrophic gastritis (CAG, N = 6), atrophic gastritis with intestinal metaplasia (IM, N = 31), atrophic gastritis with dysplasia (DYS, N = 114) and normal controls (N = 13) were examined for expression of Caspase-3 protein and Ki-67 index by SABC immunohistochemistry, and for apoptosis by TdT-mediated dUTP biotin nick end labeling (TUNEL) method. Caspase-3, Ki-67 and TUNEL index were compared in different stages of gastric precancerous lesions and their correlation was analyzed.

RESULTSThe positive index of Caspase-3 protein in severe DYS (29.8% +/- 3.9%) showed no significant difference compared with that in GC (26.9% +/- 3.0%, P > 0.05), but was significantly lower than that in low (58.3% +/- 4.2%) and moderate grade DYS (50.4% +/- 4.8%), CAG (68.3% +/- 3.3%) and IM (70.9% +/- 4.3%, P < 0.05). Caspase-3 positive index was significantly correlated with that of apoptosis detected by TUNEL (r = 0.94, P < 0.05). Ki-67 index in Caspase-3 protein positive group (18.3% +/- 2.2%) was significantly lower than that in Caspase-3 negative group (48.9% +/- 3.1%, P < 0.05).

CONCLUSIONCaspase-3 protein expression was upregulated in CAG with or without IM and low or moderately low in DYS, while down-regulated in severe DYS and gastric carcinoma, and significantly positively correlated with cell apoptosis. It is suggested that down-regulated expression of Caspase-3 protein somehow contributes to gastric carcinogenesis through an imbalance between cell apoptosis and proliferation.

Adult ; Aged ; Apoptosis ; Caspase 3 ; metabolism ; Down-Regulation ; Female ; Gastric Mucosa ; enzymology ; metabolism ; pathology ; Gastritis, Atrophic ; enzymology ; metabolism ; Humans ; Ki-67 Antigen ; metabolism ; Male ; Metaplasia ; Middle Aged ; Precancerous Conditions ; enzymology ; metabolism ; Stomach Neoplasms ; enzymology ; metabolism

OBJECTIVETo study the relationship of human telomerase reverse transcriptase (hTRT) and malignant transformation of esophageal dysplasia.

METHODSTelomerase activity and hTRT expression in esophageal dysplasia (n = 47), squamous cell carcinoma (n = 29) and normal esophagus (n = 11) were detected by telomeric repeat amplification protocol (TRAP) and in situ hybridization, respectively.

RESULTSTelomerase activity was detected in none of the 11 cases of normal esophageal tissues (0%) but in 21 of 47 cases (44.7%) of dysplasia, and in 25 of 29 cases (86.2%) of esophageal squamous cell carcinoma. There were statistically significant differences among the telomerase activity in normal esophagus, esophageal dysplasia, and in squamous cell carcinoma (chi(2) = 5.89, P < 0.05; chi(2) = 11.35, P < 0.01). hTRT mRNA was expressed in none of the 11 cases of normal esophageal tissues (0%) but in 23 of 47 cases (48.9%) of dysplasia, and in 24 of 29 cases (82.8%) of esophageal squamous cell carcinoma. There were statistically significant differences among the expression of hTRT mRNA in normal esophagus, esophageal dysplasia, and in squamous cell carcinoma (chi(2) = 6.99, P < 0.01; chi(2) = 7.32, P < 0.01). Significant correlation was found between the telomerase activity and the expression of hTRT mRNA (chi(2) = 57.91, P < 0.001).

CONCLUSIONThe mRNA expression of hTRT which paralleled to telomerase activity implied that there was a crucial role to play in regulating the activation of telomerase, and was closely related to the malignant transformation of esophageal dysplasia. hTRT might serve as a new, valuable biomarker to detect esophageal squamous cell carcinoma.

Adult ; Aged ; Biomarkers, Tumor ; analysis ; DNA-Binding Proteins ; Esophageal Neoplasms ; enzymology ; pathology ; Esophagus ; pathology ; Female ; Humans ; Male ; Middle Aged ; Precancerous Conditions ; enzymology ; pathology ; RNA, Messenger ; analysis ; Telomerase ; genetics ; metabolism

OBJECTIVESTo investigate telomerase activity in esophageal squamous cell carcinoma (SCC) and its preneoplasia lesions, and to study the relationships between telomerase activity and cancer differentiation, cancer invasiveness, and lymphatic metastasis.

METHODSTelomerase activity in esophageal SCC tissues, adjacent dysplasia tissues and normal epithelia from the surgical edge were assessed by microdissection-TRAP (telomeric repeat amplification protocol)-silver staining assay.

RESULTSTelomerase activity was detected in 37 (82.2%) of 45 esophageal tumors, 23 (79.3%) of 29 dysplasias, and 2 (5%) of 40 normal epithelia. There was a significant difference in activity between dysplasia and normal epithelium, as well as between tumor and normal epithelium. Twenty-six (92.9%) of 28 tumors with lymphatic metastasis had detectable telomerase activity compared to 11 (64.7%) of 17 non-lymphatic metastasis tumors. These relationships were statistically significant (P < 0.05), but the one between telomerase activity and tumor grade was not.

CONCLUSIONTelomerase activity was high both in esophageal SCC and their preneoplasia lesions. The telomerase activity in SCC tissue was related to lymphatic metastasis, but not to cancer differentiation.

Adult ; Aged ; Carcinoma, Squamous Cell ; enzymology ; pathology ; Cell Differentiation ; Dissection ; Esophageal Neoplasms ; enzymology ; pathology ; Female ; Humans ; Male ; Middle Aged ; Polymerase Chain Reaction ; Precancerous Conditions ; Repetitive Sequences, Nucleic Acid ; Telomerase ; genetics ; metabolism ; Telomere

BACKGROUND/AIMS: Nuclear factor-kappa B p65 (NF-kappa B p65), nuclear factor-kappa B1 p50 (NF-kappa B p50) have been shown to play a role in cell proliferation, apoptosis, cytokine production, and oncogenesis. Recently, p38 mitogen-activated protein kinase (MAPK)/ NF-kappa B/ cyclin D1 signaling pathway has been shown to play an important part in the pathogenesis of human cancers. This study was designed to investigate the expression of NF-kappa B p65, NF-kappa B p50, p38 MAPK alpha, and cyclin D1 proteins in premalignant lesions of colon and colorectal adenocarcinoma. METHODS: Paraffin sections of 20 normal mucosa, 20 low-grade tubular adenoma, 20 high-grade tubular adenoma and 64 adenocarcinoma tissues were analysed immunohistochemically for the expression of NF-kappa B p65, NF-kappa B p50, p38 MAPK alpha, and cyclin D1 proteins. RESULTS: The expression of NF-kappa B p65, NF-kappa B p50, and p38 MAPK alpha proteins were significantly higher in adenocarcinoma tissue in comparison with that in normal mucosa, low-grade tubular adenoma, and high-grade tubular adenoma tissues. Expression of NF-kappa B p50 was more frequent in poorly differentiated histologic grade, presence of nodal metastasis, and advanced stage. Expression of p38 MAPK alpha protein was higher in advanced tumor stage, presence of nodal metastasis and advanced stage. Synchronous expression of NF-kappa B p65, NF-kappa B p50, p38 MAPK alpha, and cyclin D1 proteins were significantly higher in adenocarcinoma tissue. CONCULSIONS: With the increased expression of NF-kappa B p65, NF-kappa B p50, and p38 MAPK alpha proteins, p38 MAPK/ NF-kappa B/ cyclin D1 signaling pathway may play a role in the pathogenesis of colorectal carcinoma.
Adenocarcinoma/enzymology/*metabolism/pathology ; Colorectal Neoplasms/enzymology/*metabolism/pathology ; Cyclin D1/immunology/*metabolism ; Data Interpretation, Statistical ; Female ; Humans ; Immunohistochemistry ; Intestinal Mucosa/metabolism ; Male ; Middle Aged ; NF-kappa B/immunology/*metabolism ; NF-kappa B p50 Subunit/immunology/metabolism ; Neoplasm Staging ; Precancerous Conditions/enzymology/*metabolism ; Transcription Factor RelA/immunology/metabolism ; p38 Mitogen-Activated Protein Kinases/*metabolism