The human transcription factor SOX4 was 5-fold up-regulated in bladder tumors compared with normal tissue based on whole-genome expression profiling of 166 clinical bladder tumor samples and 27 normal urothelium samples. Using a SOX4-specific antibody, we found that the cancer cells expressed the SOX4 protein and, thus, did an evaluation of SOX4 protein expression in 2,360 bladder tumors using a tissue microarray with clinical annotation. We found a correlation (P < 0.05) between strong SOX4 expression and increased patient survival. When overexpressed in the bladder cell line HU609, SOX4 strongly impaired cell viability and promoted apoptosis. To characterize downstream target genes and SOX4-induced pathways, we used a time-course global expression study of the overexpressed SOX4. Analysis of the microarray data showed 130 novel SOX4-related genes, some involved in signal transduction (MAP2K5), angiogenesis (NRP2), and cell cycle arrest (PIK3R3) and others with unknown functions (CGI-62). Among the genes regulated by SOX4, 25 contained at least one SOX4-binding motif in the promoter sequence, suggesting a direct binding of SOX4. The gene set identified in vitro was analyzed in the clinical bladder material and a small subset of the genes showed a high correlation to SOX4 expression. The present data suggest a role of SOX4 in the bladder cancer disease. (Cancer Res 2006; 66(7): 3434-42)

Heat shock protein 70-2 (Hsp70-2) is a chaperone protein essential for the growth of spermatocytes and cancer cells. Here, we show that Hsp70-2 depletion triggers lysosomal membrane permeabilization and cathepsin-dependent cell death and identify lens epithelium-derived growth factor (LEDGF) as an Hsp70-2-regulated guardian of lysosomal stability in human cancer. Knockdown of LEDGF in cancer cells induces destabilization of lysosomal membranes followed by caspase-independent and Bcl-2-resistant cell death. Accordingly, ectopic LEDGF stabilizes lysosomes and protects cancer cells against cytotoxicity induced by anticancer agents that trigger the lysosomal cell death pathway. Remarkably, ectopic LEDGF also increases the tumorigenic potential of human cancer cells in immunodeficient mice, and LEDGF expression is increased in human breast and bladder carcinomas correlating with that of Hsp70-2 in invasive bladder cancer. Taken together, these data reveal LEDGF as an oncogenic protein that controls a caspase-independent lysosomal cell death pathway. [Cancer Res 2007;67(6):2559-67]

Bladder cancer is among the most prevalent malignancies, and is characterised by frequent tumour recurrences and localised inflammation, which may promote tissue invasion and metastasis. Microarray analysis was used to compare gene expression in normal bladder urothelium with that in tumours at different stages of progression. The innate immune response gene, interferon-stimulated gene 15 kDa (ISG15, GIP2), was highly expressed at all stages of bladder cancer as compared to normal urothelium. Western blotting revealed a tumour-associated expression of ISG15 protein. ISG15 exhibited a stage-associated expression, with significantly (Po0.05) higher levels of ISG15 protein in muscle-invasive T2 -T4 tumours, compared with normal urothelium. Although ISG15 is involved in the primary immune response, ISG15 expression did not correlate with bladder inflammation. However, immunohistochemical staining revealed expression of ISG15 protein in both cancer cells and stromal immune cells. Interestingly, a significant fraction of ISG15 protein was localised to the nuclei of tumour cells, whereas no nuclear ISG15 staining was observed in ISG15-positive stromal cells. Taken together, our findings identify ISG15 as a novel component of bladder cancer-associated gene expression.

At present, the mechanism leading to bladder cancer is still poorly understood, and our knowledge about early events in tumorigenesis is limited. This study describes the changes in gene expression occurring during the neoplastic transition from normal bladder urothelium to primary Ta tumours. Using DNA microarrays, we identified novel differentially expressed genes in Ta tumours compared to normal bladder, and genes that were altered in high-grade tumours. Among the mostly changed genes between normal bladder and Ta tumours, we found genes related to the cytoskeleton (keratin 7 and syndecan 1), and transcription (high mobility group AT-hook 1). Altered genes in high-grade tumours were related to cell cycle (cyclin-dependent kinase 4) and transcription (jun d proto-oncogene). Furthermore, we showed the presence of high keratin 7 transcript expression in bladder cancer, and Western blotting analysis revealed three major molecular isoforms of keratin 7 in the tissues. These could be detected in urine sediments from bladder tumour patients.

We have analysed the occurrence of the extracellular glycoprotein vitronectin in carcinomas and normal tissue of human breast. Immunohistochemical analysis of carcinomas revealed a strong vitronectin accumulation in extracellular matrix (ECM) around some cancer cell clusters and in the subendothelial area of some blood vessels. In normal tissue, vitronectin had a homogeneous periductal occurrence, with local accumulation much lower than that in the carcinomas. Using a new solid phase radioligand assay, the vitronectin concentrations of extracts of carcinomas and normal breast tissue were determined and found to be indistinguishable. Comparison of the vitronectin and the hemoglobin concentrations of the extracts showed that their vitronectin content was not derived from blood contamination. Vitronectin mRNA was undetectable in both carcinomas and normal tissue. We conclude that vitronectin is not synthesised locally in breast tissue but derived by leakage from vessels, followed by extracellular accumulation in patterns distinctly different in carcinomas and normal tissue. The observation of a high vitronectin content in the carcinomas and its localisation in the tissue contributes to the clarification of the role of vitronectin in tumour biology in interaction with the plasminogen activation system and integrins.