Ocular clusterin expression in von Hippel-Lindau disease.

PURPOSE: Clusterin is a multifunctional glycoprotein. Its mRNA is ubiquitously expressed, with high levels in von Hippel-Lindau (VHL) target organs such as the brain, liver, kidney, and adrenal medulla. Decreased clusterin secretion has been reported in renal cell carcinoma associated with VHL disease. The purpose of this study was to investigate ocular clusterin expression in VHL disease.
METHODS: This retrospective case series included nine eyes with retinal hemangioblastoma/hemangioma associated with VHL disease, one eye from a patient with a history of VHL disease and central nervous system hemangioblastomas but without ocular lesions, one surgically-excised optic nerve with optic nerve hemangioblastoma/hemangioma, and three normal control eyes. Ocular specimens were evaluated by routine histology, immunohistochemistry for clusterin expression, and molecular detection of clusterin transcripts within ocular VHL hemangioblastomas compared with normal tissue from the same eye using microdissection and quantitative real-time PCR.
RESULTS: All retinal hemangioblastoma were composed of typical VHL tumor cells admixed with small vascular channels as well as glial cells. Marked decrease of clusterin immunoreactivity was detected in all retinal hemangioblastoma and the optic nerve hemangioblastoma, whereas positive clusterin reactivity of the vascular and glial components was similar to that of normal retina. Quantitative real-time PCR analysis confirmed the decrease of clusterin mRNA in the VHL associated retinal hemangioblastoma and optic nerve hemangioblastoma in five cases.
CONCLUSIONS: Clusterin shows possible important functions in tumor suppression by the VHL gene product (pVHL) and the potential to be a novel biomarker in retinal hemangioblastoma associated VHL disease. Further investigation of clusterin may provide better understanding of retinal hemangioblastoma associated with VHL disease.