To delineate more precisely the somatic von Hippel-Lindau disease (VHL) gene alteration as well as to elucidate its etiologic role in renal tumorigenesis, we examined a total of 240 sporadic renal cell carcinomas (RCCs) for somatic VHL gene alterations by DNA-SSCP followed by sequencing, methylation-specific PCR assay, microsatellite LOH study, and Southern blot analysis. Intragenic mutation of the VHL gene was found exclusively in clear-cell or variant-type RCCs at a frequency of 51% (104/202). Hypermethylation of the VHL promoter region was detected in an additional 11 clear-cell RCCs. Microsatellite analysis demonstrated that LOH of the VHL locus was found in 140/155 (90%) informative clear-cell RCCs. The VHL gene therefore seems to be inactivated in a two-hit manner by intragenic mutation or hypermethylation plus allelic loss in clear-cell RCC. Genomic rearrangement of the VHL gene detected by Southern analysis was not found (0/216 cases); this is in contrast to germ lines in which Southern aberrations consisted of 7-19% of the mutations. Clinicopathologic data demonstrated that VHL mutation/LOH did not vary according to tumor progression in clear-cell RCC, including tumor diameter, stage, grading, distant metastasis, and lymph node metastasis. Interestingly, VHL mutation was significantly less frequent in RCCs occurring in younger (< or = 55 years) than that in older (> or = 56 years) patients. These data suggested that the inactivation of the VHL tumor-suppressor gene is a specific genetic change in clear-cell RCC, and that it may occur at an early or first step in the clear-cell tumorigenic pathway rather than as a late event.

The present results indicate that telomerase activity might be a marker for detecting malignancy of the prostate and evaluating the malignant potential of prostate cancer.

Transcription factor NF-B plays a significant role in regulating genes involved in immune response, cell growth and differentiation, and even viral activity (reviewed by Siebenlist et al. (1) and Baeuerle and Henkel (2)). The gene expression of human immunodeficiency virus (HIV) 1 is also regulated by NF-B, suggesting that NF-B plays a critical role in acquired immunodeficiency syndrome (AIDS) (3), and a great effort has been made to analyze the activating mechanisms of NF-B. In many cells, NF-B is usually present as a latent form bound to IB, preventing NF-B from entering into the nucleus. Among IB molecules, IB-␣ is the most well-characterized because of its wide expression and the fact that it has been initially cloned among IB. The activation of NF-B is induced by a variety of extracellular stimuli including cytokines such as tumor necrosis factor ␣ (TNF␣), phosphatase inhibitors such as okadaic acid, protein synthesis inhibitors such as cycloheximide, cellular stress such as ultraviolet irradiation, and viral infection (1, 2). Some of these stimuli cause the degradation and disappearance of . Accumulating data also show that the disappearance of the IB-␣ is critical for the signal-dependent activation of NF-B and that phosphorylation and ubiquitination of IB-␣ precedes the degradation (9 -17). Unfortunately, however, the signaling pathways for these events are poorly understood, although the participation of some signaling molecules such as Ras (18,19), Raf (18,20,21), and protein kinase C isozymes nPKC⑀ (22, 23) and aPKC (19,24,25) have been reported to activate B site-dependent gene expression.MEK kinase is an activator of SAPKs/JNK1 (26,27). SAPKs/ JNK1 are distantly related members of the MAP kinase family, which are enzymes activated by stress and inflammatory cytokines, but only slightly or not at all by growth factors or phorbol esters (28,29).The similarity between the agents that cause the activation of SAPKs/JNK1, such as TNF␣ or UV irradiation (28,29), and those that cause the activation of NF-B (1, 2) prompted us to examine the involvement of MEK kinase in the activation of NF-B and the disappearance of IB-␣. MATERIALS AND METHODSPlasmids-MEK kinase cDNA was isolated by a reverse transcription-polymerase chain reaction procedure using mouse brain mRNA as a template following the published sequence information (30). The cDNA was inserted into the EcoRI site of the vector SRD, a derivative of SR␣-296 (31). The kinase-negative mutant of MEK kinase (KM-MEKK), where bases 1780 -1782 are changed from AAA to ATG resulting in an amino acid substitution at 432 of Lys to Met (27), was inserted into the EcoRI site of SRD vector. Human MAD3 cDNA (32) from base 1 to 1128 was isolated following a standard procedure and inserted into the EcoRI site of SRD vector. All of the protein coding region of CAT from pSV2-CAT (33) was inserted into SRD vector yielding SRD-CAT. B-CAT (p-55A2) and mutant B-CAT (p-55A3) plasmids were described previously (34). HIV-LTR-luciferase plasmid (35) 13234by guest on May 13, 2...

A photoexcited titanium dioxide surface has a strong ability to decompose water into hydrogen and oxygen. We have studied this effect in order to use it to kill cancer cells in vitro and in vivo. A distinct cell killing effect was observed on cultured T-24 human bladder cancer cells treated with titanium dioxide particles and 300-400 nm UV light irradiation. Titanium dioxide plus UV light also dramatically suppressed the tumour growth of T-24 cells that were implanted in nude mice. Cells cultured on the titanium dioxide electrode were also killed under UV irradiation when the electrode was anodically polarised, suggesting that photogenerated holes are involved in the cell killing. The cell killing effect caused by titanium dioxide particles plus UV light irradiation was significantly hampered in the presence of L-cysteine and catalase, scavengers of hydroxyl radicals and hydrogen peroxide respectively. Transmission electron microscopic observations showed the titanium dioxide particles to be distributed on the cell surface and inside the cells. These results suggest that titanium dioxide particles under UV light irradiation produced photogenerated holes on the surface yielding hydroxyl radicals and hydrogen peroxide inside or outside the cells and the cells were then killed by the action of these highly oxidising molecules. The possible application of photoexcited titanium dioxide particles to cancer treatment as a new anti-cancer modality is discussed. Images Figure 6

Partial or total transarterial ablation of arteriovenous malformations with alcohol proved effective for long-term cessation of hematuria. However, this procedure as well as transarterial embolization has the potential risk of nontarget infarction.