Chemosensitization of human renal cell cancer using antisense oligonucleotides targeting the antiapoptotic gene clusterin.

BACKGROUND: Renal cell cancer (RCC) is a chemoresistant disease with no active chemotherapeutic agent achieving objective response rates higher than 15%. Clusterin is a cell survival gene that increases in human renal tubular epithelial cells after various states of injury and disease. Downregulation of clusterin, using antisense oligonucleotides (ASO), has recently been shown to increase chemosensitivity in several prostate cancer models. The objectives in this study were to evaluate clusterin expression levels in human RCC and normal kidney tissue, and to test whether clusterin ASO could also enhance chemosensitivity in human RCC Caki-2 cells both in vitro and in vivo. METHODS: Immunohistochemical staining was used to characterize clusterin expression in 67 RCC and normal kidney tissues obtained from radical nephrectomy specimens. Northern blot analysis was used to assess changes in clusterin mRNA expression after ASO and paclitaxel treatment. The effects of combined clusterin ASO and paclitaxel treatment on Caki-2 cell growth was examined using an MTT assay. Athymic mice bearing Caki-2 tumors were treated with clusterin ASO alone, clusterin ASO plus paclitaxel, and mismatch control oligonucleotides plus paclitaxel, over a period of 28 days with measurement of tumor volumes once weekly over 8 weeks. RESULTS: Immunohistochemistry of normal and malignant kidney tissue sections of 67 patients demonstrated positive clusterin staining for almost all RCC (98%) and an overexpression, compared to normal tissue, in a majority of RCC (69%). Clusterin ASO, but not mismatch control oligonucleotides, decreased clusterin mRNA expression in Caki-2 cells in a dose-dependent and sequence-specific manner. Pretreatment of Caki-2 cells with clusterin ASO significantly enhanced chemosensitivity to paclitaxel in vitro. Characteristic apoptotic DNA laddering was observed after combined treatment with ASO plus paclitaxel, but not with either agent alone. In vivo administration of clusterin ASO plus paclitaxel acted synergistically to increase apoptosis and significantly delay Caki-2 tumor growth, compared to mismatch control oligonucleotide plus paclitaxel. In addition, TUNEL staining revealed increased apoptotic cells in tumors treated with clusterin ASO plus paclitaxel compared to treatment with either clusterin ASO or paclitaxel alone. CONCLUSION: These findings confirm that the use of clusterin ASO may be a feasible strategy to enhance chemosensitivity for patients with advanced RCC.

Radiofrequency ablation followed by resection of malignant liver tumors.

BACKGROUND: Radiofrequency ablation (RFA) has recently been used to treat liver tumors, but few clinical reports have described the pathological characteristics of radiofrequency ablation in human specimens. This study delineates the gross pathologic and histochemical changes induced by RFA in benign and malignant human liver tissue and confirms the tumor necrosis described in early clinical reports. METHODS: Ten patients with metastatic tumors of the liver received a single treatment of ultrasound-guided percutaneous RFA to 12 tumors. Hepatic resection was carried out within 6 weeks of RFA. Specimens were stained with standard hematoxylin and eosin stain followed by oxidative stain to determine if there was evidence of viable tumor within the zone of ablation. RESULTS: Nine of the 12 ablations were resected. Microscopic examination within the zone of ablation showed successful ablation in 8 of the 9 resected ablations. CONCLUSIONS: Percutaneous RFA creates well-circumscribed areas of tumor necrosis with apparent cell death using an oxidative stain. Further investigation is encouraged to determine the clinical effectiveness of radiofrequency ablation in the complete destruction of liver tumors for palliative or curative intent.

Coexisting carcinoid tumors in familial adenomatous polyposis-associated upper intestinal adenomas.

Upper gastrointestinal polyps and extraintestinal tumors are well recognized in association with familial adenomatous polyposis (FAP). Although carcinoid tumors have been reported in association with sporadic colonic neoplasms and ulcerative colitis, to date, carcinoids have not been reported in association with FAP. We report a patient with FAP who has recurrent carcinoid tumors located at the bases of duodenal adenomas. The genetic basis of carcinoid neoplasms is still uncertain. This report may represent the clinical effect of the APC gene mutation on the enterochromaffin cell line manifesting as recurrent carcinoid tumors in physical association with intestinal adenomas. Future genetic analysis and epidemiological studies may be of value in determining whether a true association exists.