Detection of BCL-2 RNA in low grade tumours of the urinary bladder

Abnormal expression of bcl-2 and bax in rat tongue mucosa during the development of squamous cell carcinoma induced by 4-nitroquinoline 1-oxide

4-Nitroquinoline 1-oxide (4NQO)-induced rat tongue carcinogenesis is a useful model for studying oral squamous cell carcinoma. The aim of this study was to investigate the expression of bcl-2 and bax during tongue carcinogenesis induced by 4NQO. Male Wistar rats were distributed into three groups of 10 animals each and treated with 50 ppm 4NQO solution through their drinking water for 4, 12 or 20 weeks. Ten animals were used as negative control. Although no histological changes were induced in the epithelium after 4 weeks of carcinogen exposure, bcl-2 and bax were over-expressed (P < 0.01) in all layers of the 'normal' epithelium. The expression levels were the same in all layers of epithelium for both the antibodies used (bcl-2 or bax). In dysplastic lesions at 12 weeks following carcinogen administration, the levels of bcl-2 and bax expression did not increase when compared to negative control with the immunoreactivity for bcl-2 being restricted to the superficial layer of epithelium. In well-differentiated squamous cell carcinoma induced after 20 weeks of treatment with 4NQO, bcl-2 was expressed in some cells of tumour islands. On the other hand, immunostaining for bax was widely observed at the tumour nests. The labelling index for bcl-2 and bax showed an increase (P < 0.05) after only 4 weeks of 4NQO administration. In conclusion, our results suggest that abnormalities in the apoptosis pathways are associated with the development of persistent clones of mutated-epithelial cells in the oral mucosa. Bcl-2 and bax expression appears to be associated with a risk factor in the progression of oral cancer.

Incidence of Bcl-2 expression in bladder cancer: relation to schistosomiasis

OBJECTIVES

Apoptosis (programmed cell death) and the genes regulating this process (e.g., Bcl-2) have recently become a focus of interest in the study of cancer development and progression. The bcl-2 gene product plays a role as an inhibitor of apoptosis; it contributes to oncogenesis by suppressing signals that induce apoptotic cell death. The aim of this study was to determine the expression of bcl-2 in schistosomal bladder cancer and to compare it with the established clinicopathological factors.

METHODS

Tumor tissues from 118 patients with bladder cancer were examined [57 with squamous cell carcinoma (SCC) and the remaining 61 with transitional cell carcinoma (TCC)]. Of 118 patients, 60 had schistosomiasis associated with bladder cancer. Bcl-2 expression was determined by enzyme immunoassay and the results were confirmed by Western blot and immunodot blot techniques.

RESULTS

Bcl-2 was significantly expressed in SCC compared to those with TCC type in the presence of schistosomiasis. Moreover, bcl-2 was associated with clinical stages and lymph node involvement but not with histological grades.

CONCLUSIONS

These observations detect a potential role for bcl-2 expression in schistosomal carcinogenesis, and hence selecting patients for future anti-bcl-2 therapy.

Expression and prognostic significance of LIVIN, SURVIVIN and other apoptosis-related genes in the progression of superficial bladder cancer

BACKGROUND

It has been suggested that progression of superficial bladder cancer may be regulated at the molecular level by a typical pattern of expression of genes involved in apoptosis. Recently LIVIN, belonging to the inhibitors of apoptosis (IAP) family, has been found to be expressed in most solid tumors, where its expression is suggested to have prognostic significance. No data are available concerning the significance of LIVIN in the progression of bladder tumors.

PATIENTS AND METHODS

In the present paper we used RT-PCR to investigate the expression of LIVIN isoforms alpha and beta, SURVIVIN, BCL-X and BCL-2/BAX expression ratio both in normal and tumoral bladder tissues, and correlated their expression with the emergence of early relapses in a follow-up of 4 years. This study shows that only the alpha isoform of LIVIN, which is not expressed in normal bladder tissue, is expressed in a proportion of tumors with a high risk of relapse.

RESULTS

LIVIN was found in 7/30 patients (23%), SURVIVIN in 9/30 (30%), BCL-2/BAX ratio >1 in 16/30 (53%), BCL-2/BAX expression ratio <1 in 14/30 (46.6%) and BCL-X, only in isoform BCL-X(L), in 11/30 (36.6%). When we evaluated the dependence between each gene expression and relapse free time of patients, we found that LIVIN, high BCL-2/BAX ratio and BCL-X(L), but not SURVIVIN, reached statistical significance in order to predict relapses.

CONCLUSIONS

Our findings suggest that LIVIN may be involved in the progression of superficial bladder cancer and used as a marker of early recurrence; while the expression of SURVIVIN cannot be used to identify patients with high risk of relapse.

Bcl-2/bax mRNA expression ratio as prognostic factor in low-grade urinary bladder cancer

Apoptotic cell death represents an important mechanism for the precise regulation of cell numbers, and a defence mechanism against tumoral cell. bcl-2 and bax genes are known to be involved in the control of apoptotic pathways; in particular, the ratio between bcl-2 and bax represents a cell rheostat that is able to predict a cell's response toward life or death to an apoptotic stimulus. In the present study we investigated the role of bcl-2 and bax gene expression in a panel of 37 low-grade tumours of the urinary bladder, and correlated the expression of these genes to the prognosis of patients in a follow-up of more than one year. We found that levels of bax expression higher than bcl-2 in bladder tumours well correlates to a better outcome for patients. Early relapses are much more frequently observed in those patients whose tumours express more bcl-2 than bax mRNA. We conclude that the bcl-2/bax expression ratio may be considered as a marker for disease progression in low grade bladder tumours, independently of clinical staging and histological grading.