Advantages of a two-chamber culture system to test drug nephrotoxicity: the example of cephaloridine

BACKGROUND: The adult prostate is maintained through an equilibrium between cell growth and death rates. Androgen deprivation induces an increase in intracellular Ca++, AP-1 gene expression of androgen-inducible genes. METHODS: Northern blot analysis, band-shift assays, and transient cotransfection assays were used to study the effects of Ca++ mobilizer A23187 on gene expression in human prostate cancer cells. RESULTS: A23187 repressed androgen-upregulated mRNAs for prostate-specific antigen (PSA) and hKLK2, and rapidly induced mRNA levels for c-fos and c-jun. AP-1 protein-DNA binding activities were elevated after A23187 treatments. Androgen receptor (AR)-mediated induction of chloramphenicol acetyltransferase (CAT) reporter was repressed by AP-1 proteins. CONCLUSIONS: The repression of AR-mediated induction of PSA and hKLK2 genes by Ca++ mobilizers is due to the interference of AR transactivation activity by AP-1 proteins.     

Matrix metalloproteinase-1 in cholesteatoma, middle ear granulations and deep meatal skin: a comparative analysis

The products of c-fos and c-jun proto-oncogenes form the heterodimeric complex AP-1 (activator protein 1), which play an important part in the control of bone cell proliferation and differentiation and in the development of bone tumours. We examined the expression of c-fos and c-jun in a series of 52 primary skeletal neoplasms, using an immunohistochemical method on formalin-fixed, paraffin-embedded sections. The expression of c-fos and c-jun was restricted to bone-forming lesions, while cartilaginous tumours were devoid of immunoreactivity. In benign osteoblastic lesions moderate c-fos and c-jun expression was found in 2 cases (18.1%). The highest levels of c-fos and c-jun expression were detected in high-grade central osteosarcomas (7 of 15 cases with moderate/diffuse expression) while 1 telangiectatic osteosarcoma, 2 low-grade central osteosarcomas, 1 low-grade periosteal osteosarcoma and 7 low-grade parosteal osteosarcomas were either negative or had low expression. The high-grade component of a dedifferentiated parosteal osteosarcoma showed diffuse immunoreactivity for both oncoproteins. Comparison of c-fos and c-jun expression by histological grade showed that high-grade osteosarcomas had a significantly higher expression of both oncoproteins than did low-grade osteosarcomas (P = 0.01, Fisher's exact test). Thus, c-fos and c-jun overexpression may be implicated in the development of high-grade osteosarcomas, but they appear to have little or no relevance for the development of low-grade osteosarcomas and cartilaginous skeletal neoplasms.     

P-glycoprotein associated expression of c-fos and c-jun products in human lung carcinomas

Surgical specimens of non-small cell lung carcinomas of 167 previously untreated patients were analyzed for expression of c-fos, c-jun, c-myc and c-neu products and for resistance to drugs. Because most of the patients were treated only by surgery, an in vitro test was used to determine the resistance. For the detection of the oncoproteins the streptavidin-biotin-peroxidase-complex method was used. An association between the resistance and c-fos and c-jun proteins was found (c-fos p = 0.01, c-jun p = 0.09), whereas a correlation between resistance and expression of c-neu and c-myc products was not observed. P-glycoprotein 170 was detected immunohistochemically in 91 tumors using the monoclonal antibody JSB-1. There was a significant correlation between the resistance measured by the in vitro test and P-glycoprotein 170 expression (p < 0.001). Also a significant correlation between the c-fos and c-jun proteins and the expression of P-glycoprotein was found (c-fos p = 0.017, c-jun p = 0.036). In contrast, no significant relationship was found between the expression of the c-neu or c-myc products and the expression of P-glycoprotein 170. Thus, there exists a significant relationship between resistance, P-glycoprotein 170, and c-fos and c-jun products in human non-small cell lung carcinomas. P-glycoprotein 170 may be regulated by the c-fos/c-jun protein complex, which binds specifically to AP-1.     

Attenuation of cell death mediated by membrane depolarization different from that by exogenous BDNF in cultured mouse cerebellar granule cells

Membrane depolarization accompanying calcium (Ca2+) influx into neurons is thought to play an essential role in controlling the survival and death of cultured mouse cerebellar granule cells (CGCs). In this study, we sequentially controlled the survival and death of CGCs in culture and monitored the expression of several kinds of genes including brain-derived neurotrophic factor (BDNF) gene. Deprivation and subsequent induction of membrane depolarization by lowering and re-elevating the extracellular concentration of potassium chloride, respectively, led to death of CGCs and then to an attenuation of the death process depending upon the Ca2+ influx into CGCs through voltage-dependent calcium channels (VDCCs). De novo protein synthesis was critical for attenuating the death of non-depolarized CGCs. Accompanying this attenuation was an activation of c-fos and BDNF genes and an inactivation of c-jun and neurotrophin-3 (NT-3) genes. The attenuation of cell death mediated by exogenous BDNF was only partial compared to that by membrane depolarization, suggesting that not only BDNF but also other factors could be involved in the membrane depolarization-mediated attenuation of death of CGCs. In good agreement with this observation, the mode of activation of c-fos, c-jun, BDNF and NT-3 genes induced by exogenous BDNF was different from that induced by membrane depolarization. Thus, membrane depolarization effectively attenuates the death of non-depolarized CGCs, the mode of which seems to be different from that mediated by BDNF alone.