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Biomedical subjects

P Bedossa

Publications and source records attributed to P Bedossa.

At least 19 recordsLinked to original sources
PubMed2001

In situ detection of telomerase enzymatic activity in human hepatocellular carcinogenesis.

Telomerase enzymatic activity has been detected in most human malignant tumours including hepatocellular carcinoma. In order to assess the cellular source, the topographic distribution, and the chronology of telomerase re-expression during human liver carcinogenesis, an in situ technique derived from the standard TRAP (telomeric repeat amplification protocol) assay was set up that allowed the detection of telomerase enzyme activity at the cellular level on frozen liver tissue sections. In situ TRAP (ISTRAP) was performed on 27 hepatocellular carcinomas (HCCs) and 57 non-tumour livers, including normal liver without HCC, liver samples adjacent to tumour with and without hepatic cirrhosis, and biopsies of chronic hepatitis. In HCC, telomerase was detected in the nuclei of liver tumour cells in 23/27 cases (85%), with a heterogeneous distribution within the tumour. This signal was also detected in clusters of hepatocytes in 16/26 (61%) samples of liver adjacent to HCC, in 10/23 (43%) cases of chronic viral hepatitis without adjacent HCC, and in scattered nuclei of 2/8 histologically normal livers. Comparison of the results obtained with ISTRAP and standard TRAP assays on tissue extracts suggests a gain in sensitivity with the in situ technique. This study confirms that telomerase is expressed in most HCCs and suggests that focal telomerase reactivation is an early event during human liver carcinogenesis. ISTRAP is a sensitive technique that allows the study of telomerase expression in the morphological context.

Adult↗
PubMed2001

hTERT expression in sporadic renal cell carcinomas.

Human telomerase is a specialized reverse transcriptase that catalyses telomeric repeat addition at the ends of chromosomes. Activation of this enzyme is one of the key steps in cell immortalization and carcinogenesis, and one of its components, hTERT, is considered as the rate-limiting factor. While telomerase activity was found to be prognostically relevant in various cancers, results obtained from renal cell carcinomas (RCC) failed to show any correlation with the usual prognostic factors. The aim of the study was to reassess the role of telomerase and its hTERT component in the biological behaviour of RCC using new quantitative techniques, such as the quantitative evaluation of hTERT mRNA level by a real-time RT-PCR procedure and the measuring of telomerase activity by an ELISA TRAP assay. Since experimental evidence supports a relationship between cell proliferation or c-myc expression and telomerase, the proliferation index and c-myc mRNA levels were also studied. Forty-one RCC (29 conventional renal cell carcinomas (CRCC), 10 papillary RCC and two urothelial carcinomas) were studied. In 73% of cases, normalized hTERT mRNA expression was significantly higher in the tumour sample than in the normal tissue. Telomerase activity was detected in 63% of RCC, while corresponding normal tissue was always negative. Analysis of correlations showed firstly that both telomerase activity and hTERT mRNA level were lower in the group of CRCC versus non-CRCC (TRAP: 0.3+/-0.1 versus 0.6+/-0.2, p<0.05; hTERT/PO mRNA: 5+/-3 versus 37+/-8, p<0.001, respectively); secondly, that in the group of CRCC, hTERT mRNA expression level was correlated with the stage of the tumour (p=0.01); and thirdly, that no correlation was observed between c-myc mRNA level and hTERT mRNA level. In conclusion, these results support the involvement of telomerase in RCC and the potential interest of hTERT mRNA quantification.

Adult↗
PubMed2001

Abnormal E-cadherin expression and prostate cell blood dissemination as markers of biological recurrence in cancer.

Until now, no molecular parameter has been available for predicting the metastatic potential of prostate tumours, which leaves their outcome uncertain despite an apparent benign histology or early stage. Abnormal expression of adhesion molecules, such as E-cadherin, can be contributing factors for increased invasiveness and metastatic potential. Histological analysis for E-cadherin expression was carried out on paraffin-embedded tumour tissues. Tumour metastatic potential was indirectly evaluated by detecting circulating prostate cells (CPC), using reverse transciptase-polymerase chain reaction (RT-PCR) and prostate-specific membrane antigen (PSMA) as a target. Patients were followed-up for a median of 14 months (range 10--19 months) after surgery with serum prostate-specific antigen (PSA) level measurement. Interestingly, 23 of 44 localised tumours exhibited aberrant E-cadherin expression. Prior to primary surgery, PSMA RT-PCR detected the spread of prostate cells to the blood in 24 patients. Statistical analysis showed that abnormal E-cadherin expression in the tumours was the only variable that was independently correlated with prostate cell dissemination in the blood (P<0.0001). In logistic regression analysis, abnormal E-cadherin expression was a significant independent predictor for a later biological relapse. This impaired adhesion status was clearly correlated with a haematogenous spread of the primary tumour cells. It could therefore be an objective way to restrict the indications for radical surgery to patients not presenting with this feature.

Adult↗
PubMed2001

Replicative senescence in normal liver, chronic hepatitis C, and hepatocellular carcinomas.

There is growing evidence that senescent cells accumulate in vivo and are associated with the aging process in parallel with the progressive erosion of telomeres. Because recent data show that telomere shortening is involved in the pathogenesis of liver cirrhosis, we looked for replicative senescence cells in normal livers, chronic hepatitis C, and hepatocellular carcinoma (HCC). Replicative senescent cells were detected on liver tissue cryosections using expression of a specific marker, senescence-associated beta-galactosidase, a cytoplasmic enzyme detected at pH 6. A total of 57 frozen liver samples (15 normal liver, 32 chronic hepatitis C, and 10 HCCs) were studied. Replicative senescence was graded as absent in 56% of cases (32 of 57) and present in 44% (25 of 57). Replicative senescence was considered present in 3 of 15 normal livers (20%), 16 of 32 chronic hepatitis cases (50%), and 6 of 10 HCCs (60%). In the group of nontumoral livers, the presence of senescent cells in liver was associated with older age (P =.03). In the group with chronic hepatitis C, fibrosis stage, but not activity grade, was significantly correlated with the accumulation of replicative senescent cells (P <.001). Finally, beta-Gal staining in nontumoral tissue was strongly correlated with the presence of HCC in the surrounding liver (P <.001). These results suggest that chronic hepatitis C represents a relevant model of accelerated replicative senescence and that accumulation of replicative senescent cells predispose to HCC development. Detection of replicative senescent cells may then serve as a predictive marker of a hepatocellular carcinoma in the surrounding tissue. HUM PATHOL 32:327-332.

Carcinoma, Hepatocellular↗
PubMed2001

High glucose and hyperinsulinemia stimulate connective tissue growth factor expression: a potential mechanism involved in progression to fibrosis in nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) may progress to liver fibrosis and cirrhosis. Mechanisms directly involved in the development of fibrosis have been poorly investigated. Because connective tissue growth factor (CTGF) is an intermediate key molecule involved in the pathogenesis of fibrosing chronic liver diseases and is potentially induced by hyperglycemia, the aims of this study were to (1) study the expression of CTGF in vivo both in human liver biopsy specimens of patients with NASH and in an experimental model of obesity and type II diabetes (Zucker rats); and (2) analyze the effects of hyperglycemia and insulin in vitro on hepatic stellate cells. In vivo, CTGF overexpression was observed in the liver tissue of all of the 16 patients with NASH. CTGF immunostaining was mild in 7 cases (44%) and moderate or strong in 9 cases (56%). Staining was mainly detected in the liver extracellular matrix in parallel with the amount of liver fibrosis. Liver from fa/fa rats also showed CTGF overexpression by comparison with Fa/fa rats both at the messenger RNA (mRNA) level (3-fold increase) and protein level. In vitro, both CTGF mRNA and protein were significantly increased when hepatic stellate cells were incubated with either glucose or insulin. A slight increase in type I procollagen mRNA level was also observed in hepatic stellate cells incubated with glucose. In conclusion, this study suggests that hyperglycemia and insulin are key-factors in the progression of fibrosis in patients with NASH through the up-regulation of CTGF.

Adult↗
PubMed2001

[Gastric epithelioid angiosarcoma, a biopsy diagnostic pitfall].

We report the case of a 70-year-old man who presented a bulky gastric mass. The diagnosis of poorly differenciated adenocarcinoma was made on the biopsy. On surgical specimen, the final diagnosis of gastric angiosarcoma with secondary intestinal involvement was established. The patient did not respond to chemotherapy and died 8 months later. The diagnosis was difficult because of epithelioid areas which expressed both cytokeratin and vascular antigens. Human herpesvirus 8 previously detected in some soft tissue angiosarcoma was not found by polymerase chain reaction.

Aged↗
PubMed2000

Expression of vascular endothelial growth factor in renal cell carcinomas.

Vascular endothelial growth factor (VEGF) is an angiogenic factor that may be involved in tumor growth and metastasis. Only a few data concerning the role of VEGF in renal cell carcinomas (RCCs) are available, and no studies have yet evaluated its prognostic value. The aim of the present study was to assess VEGF expression in a large series of renal tumors with a long follow-up, correlated with the usual histoprognostic factors and survival. VEGF immunostaining was performed on formalin-fixed, paraffin-embedded archival tissue from 74 renal carcinomas (62 conventional renal cell and 12 papillary carcinomas). Positivity of immunostaining was semi-quantitatively scored by two pathologists. Angiogenesis was evaluated by immunostaining with anti-CD34 antibodies on serial sections. Cytoplasmic VEGF expression was detected in tumor cells in 35% (26/74) of RCCs, including 18 out of the 62 (29%) conventional RCCs and 8 out of the 12 (67%) papillary carcinomas (P=0.02). In the group of conventional RCCs, VEGF expression was positively correlated with both nuclear grade (P=0.05) and size of the tumor (P=0.05). Furthermore, a significant correlation was observed between VEGF expression and microvascular count (P=0.04). Finally, cumulative survival rate was significantly lower in the group of patients with conventional RCCs expressing VEGF (log rank test, P=0.01). In the Cox model, VEGF expression was a significant independent predictor of outcome, as well as stage and nuclear grade. This study suggests that VEGF is involved in angiogenesis in conventional RCCs and appears to be a potential prognostic factor in these tumors.

Blood Vessels↗
PubMed2000

Clonal analysis of micronodules in virus C-induced liver cirrhosis using laser capture microdissection (LCM) and HUMARA assay.

Most hepatocellular carcinomas (HCC) arise from malignant transformation of regenerative cirrhotic nodules. Because HCC has a very poor prognosis, detection of these premalignant lesions may improve the management of patients with cirrhosis. In this regard, clonal analysis of liver micronodules should be of particular interest in order to differentiate polyclonal regenerative micronodules from monoclonal neoplastic potentially malignant micronodules. To address this issue, 112 micronodules from 15 cases of explanted liver cirrhosis were carefully microdissected from paraffin-embedded tissue using a laser capture microscopy system. Clonal analysis was performed by analyzing X-chromosome inactivation, as indicated by the methylation status of the human androgen receptor gene (HUMARA). For each microdissected micronodule, a large set of pathological features was evaluated and correlated with their clonal status. Clonal analysis showed that 57 micronodules (51%) were monoclonal and 55 (49%) were polyclonal. Prevalence of monoclonal nodules ranged from 25% to 71% according to cases. In all cases, mono- and polyclonal nodules were randomly distributed in the cirrhotic liver. Although the clonal status was not significantly affected by the presence or absence of macronodules in the adjacent liver, size of monoclonal micronodules was significantly larger than size of polyclonal micronodules (mean size of the monoclonal nodules: 3 + 0.1 mm vs mean size of the polyclonal nodules: 2.5 +/- 0.1 mm, p = 0.007). Among the elementary pathological features evaluated, only the presence of iron overload was correlated with a monoclonal status (p = 0.04). In conclusion, clonal analysis of liver cirrhosis shows that 51% of micronodules are monoclonal lesions, supporting the notion that liver cirrhosis is a multineoplastic lesion. Because monoclonality is a marker of neoplasia, cirrhosis with accumulation of monoclonal nodules may be carefully followed, and monoclonal nodules should be screened for additional markers to assess their biological behavior.

Adult↗
PubMed2000

Natural history of HCV infection.

Chronic hepatitis C virus (HCV) infection affects 170 million individuals worldwide. These individuals are at risk of developing both hepatological and non-hepatological manifestations. HCV is usually only fatal when it leads to cirrhosis, the final stage of liver fibrosis. Therefore, an estimate of fibrosis progression represents an important surrogate end-point for the evaluation of the vulnerability of an individual patient. In untreated patients, the median expected time to cirrhosis is 30 years; 33% of patients have an expected median time to cirrhosis of less than 20 years and 31% will only progress to cirrhosis after more than 50 years, if ever. Several factors are associated with fibrosis progression rate: duration of infection, age, male gender, consumption of alcohol, HIV co-infection and low CD4 count. Non-hepatological manifestations are frequent with more than 70% of HCV patients experiencing fatigue or at least one extrahepatic clinical manifestation involving primarily the joints, skin and muscles. Several immunological abnormalities are frequently observed, including cryoglobulins (40%),anti-nuclear antibodies (10%) and anti-smooth muscle antibodies (7%). In contrast severe extrahepatic manifestations are rare, with 1% for systemic vasculitis.

Antibodies, Antinuclear↗
PubMed2000

Impact of interferon alfa-2b and ribavirin on progression of liver fibrosis in patients with chronic hepatitis C.

The extent of liver fibrosis is an important prognostic factor in patients infected with hepatitis C virus. Administration of a combination of interferon and ribavirin produces a superior viral clearance response rate than interferon alone. The effect of this combination regimen on hepatic fibrosis has not been established. To determine the impact of combination regimen or interferon alone on the progression of liver fibrosis we pooled individual data of 1,509 patients with pretreatment and post-treatment biopsies from 3 randomized trials. Fibrosis progression and regression rates between biopsies were calculated by the Kaplan-Meier method and by the fibrosis progression rate per year. The percentage of patients without significant fibrosis (stage 0 or 1) at 96 weeks was 68 +/- 4% (mean +/- SE) when treated by combination regimen for 48 weeks, 64 +/- 4% by interferon alone for 48 weeks, 42 +/- 7% by combination regimen for 24 weeks (lower than both 48-week regimens P <.001), and 24 +/- 9% interferon alone for 24 weeks (lower than the combination regimen for 24 weeks; P =.02). Three factors were independently associated with fibrosis reduction: sustained viral response, duration of treatment, and baseline fibrosis stage (all P <.001 in proportional hazards regression model). These results show that interferon and ribavirin combination therapy significantly reduces the rate of fibrosis progression in patients with hepatitis C. This effect was most prominent in patients who achieved a virologic response, those receiving 48 weeks of therapy, and in patients with significant fibrosis at baseline.

Adult↗