Analysis of Gene Expression in Renal Cell Carcinomas Using cDNA Microarray: Reduced Expression of Decorin in Renal Cell Carcinomas

BACKGROUND: Identification of the genes expressed differentially in renal cell carcinoma (RCC)but not in the non-cancerous kidney is important for understanding the molecular basis ofrenal cell carcinoma and for defining possible prognostic value and therapeutic intervention.We investigated the changes in gene expression accompanying the development and progression of kidney cancer by cDNA microarrays. METHODS: To identify molecular alterations in renal cell carcinoma, we measured expression profiles for paired neoplastic and noncancerouskidney samples from an individual by means of a cDNA microarry representing 7, 500genes. Of the differentially expressed genes, we assessed the decorin gene at the proteinlevel using immunohistochemistry. RESULTS: The 60 genes were noted to have more than a fivefold change in expression (either increased or decreased) in RCC compared to the noncancerouskidney. The changed genes are those associated with signal transduction, metabolizingenzymes, the cytoskeleton, cell adhesion, cell cycle control, modulation of transcription, the tumor suppressor gene and tumor antigens. Under immunohistochemistry, the expressionof decorin was significantly decreased in the tumor than in the non-cancerous kidney.The expression rate of decorin was not associated with the patient's sex, age, histologic type, Fuhrmann nuclear grade and T stage. CONCLUSION: The author predicted that these geneexpression profiling experiments will lead to improvements in the basic understanding of renaltumor pathogenesis and will promote the discovery of novel molecular markers for renal tumordiagnosis and therapy.

Primary Extragastrointestinal Stromal Tumor (EGIST) of the Greater Omentum

Gastrointestinal stromal tumors (GISTs) were recently defined as spindle cell, epithelioid, or occasionally, pleomorphic mesenchymal tumors of the gastrointestinal tract that express the CD117 (proto-oncogene c-kit protein, stem cell factor receptor), as detected using immunohistochemistry. And they show a new tendency to include the CD117-positive mesenchymal spindle cell or epithelioid neoplasms primary in the omentum and mesentery, and is so termed extragastrointestinal stromal tumors (EGISTs). Omental EGISTs are very rare and similar to their gastrointestinal counterpart. We present a case of primary EGIST of the greater omentum in a 58-year-old man. The resected tumor mass measured 20X15X5 cm and weighed 1,150 g. The cut surface displayed a central cystic change and partial mural nodules. Microscopically, most parts of the tumor were composed of round or polygonal cells, with many of them containing perinuclear vacuoles. The mitotic count was less than one per 50 high-power-fields. Immunohistochemically, the tumor cells were diffusely positive for CD117 and vimentin, and focally for smooth muscle actin and CD34. Ultrastructurally, partially smooth muscle differentiation was confirmed in this case.

Effect of cisplatin on Na+/H+ antiport in the OK renal epithelial cell line

Cis-diamminedichloroplatinum II (cisplatin), an effective antitumor agent, induces acute renal failure by unknown mechanisms. To investigate direct toxic effects of cisplatin in the renal proximal tubular transport system, OK cell line was selected as a cell model and Na+/H+ antiport activity was evaluated during a course of cisplatin treatment. The cells grown to confluence were treated with cisplatin for 1 hour, washed, and incubated for up to 48 hours. At appropriate intervals, cells were examined for Na+/H+ antiport activity by measuring the recovery of intracellular pH (pHi) after acid loading. Cisplatin of less than 50 muM induced no significant changes in cell viability in 24 hours, but it decreased the viability markedly after 48 hours. In cells exposed to 50 muM cisplatin for 24 hours, the Na+-dependent pHi recovery (i.e., Na+/H+ antiport) was drastically inhibited with no changes in the Na+-independent recovery. Kinetic analysis of the Na+-dependent pHi recovery indicated that the Vmax was reduced, but the apparent Km was not altered. The cellular Na+ and K+ contents determined immediately before the transport measurement appeared to be similar in the control and cisplatin group, thus, the driving force for Na+-coupled transport was not different. These results indicate that cisplatin exposure impairs the Na+/H+ antiport capacity in OK cells. It is, therefore, possible that in patients treated with a high dose of cisplatin, proximal tubular mechanism for proton secretion (hence HCO3- reabsorption) could be attenuated, leading to a metabolic acidosis (proximal renal tubular acidosis).

Effect of cisplatin on sodium-dependent hexose transport in LLC-PK-1 renal epithelial cells

Cis-dichlorodiammine platinum II (Cisplatin), an effective chemotherapeutic agent, induces acute renal failure by unknown mechanisms. To investigate direct toxic effects of cisplatin on the renal proximal tubular transport system, LLC-PK-1 cell line was selected as a cell model and the sugar transport activity was evaluated during a course of cisplatin treatment. Cells grown to confluence were treated with cisplatin for 60 min, washed, and then incubated for up to 5 days. At appropriate intervals, cells were tested for sugar transport activity using alpha-methyl-D-(14C)glucopyranoside (AMG) as a model substrate. In cells treated with 100 micrometer cisplatin, the AMG uptake was progressively impaired after 3 days. The viability of cells was not substantially changed with cisplatin of less than 100 micrometer, but it decreased markedly with 150 and 200 micrometer. In cisplatin-treated cells, the Na+/-dependent AMG uptake was drastically inhibited with no change in the Na+/-independent uptake. Kinetic analysis indicated that Vmax was suppressed, but Km was not altered. The Na+/-dependent phlorizin binding was also decreased in cisplatin-treated cells. However, the AMG efflux from preloaded cells was not apparently retarded by cisplatin treatment. These data indicate that the cisplatin treatment impairs Na+/-hexose cotransporters in LLC-PK-1 cells and suggest strongly that defects in transporter function at the luminal plasma membrane of the proximal tubular cells constitute an important pathogenic mechanism of cisplatin nephrotoxicity.

Pathologic changes after inferior oblique marginal myotomy in rabbits

To evaluate the histopathologic changes after an inferior oblique marginal myotomy with local injection of triamcinolone, an inferior oblique marginal myotomy was performed in 14 white rabbits and they were divided into 2 groups, one group with a local injection of triamcinolone and the other group without triamcinolone injection after a myotomy. At the postoperative one month, an edema of the muscle fibers and an infiltration of the inflammatory cells were observed and at postoperative three months, a fibrous tissue ingrowth around the muscle fibers and an atrophy of the muscle fibers were found and those changes were less prominant in the group with triamcinolone injection. The local injection of triamcinolone after the inferior oblique marginal myotomy would help in decreasing the fibrous tissue ingrowth and the formation of the scar tissue, thus it could be used in augmenting the effect of the inferior oblique marginal myotomy.

Pathologic changes after inferior oblique marginal myotomy in rabbits

To evaluate the histopathologic changes after an inferior oblique marginal myotomy with local injection of triamcinolone, an inferior oblique marginal myotomy was performed in 14 white rabbits and they were divided into 2 groups, one group with a local injection of triamcinolone and the other group without triamcinolone injection after a myotomy. At the postoperative one month, an edema of the muscle fibers and an infiltration of the inflammatory cells were observed and at postoperative three months, a fibrous tissue ingrowth around the muscle fibers and an atrophy of the muscle fibers were found and those changes were less prominant in the group with triamcinolone injection. The local injection of triamcinolone after the inferior oblique marginal myotomy would help in decreasing the fibrous tissue ingrowth and the formation of the scar tissue, thus it could be used in augmenting the effect of the inferior oblique marginal myotomy.