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L.I. Paraoan, D. Gray, P. Hiscott, I. Grierson, B. Damato; Expression of p53–Induced Apoptosis Effector in Uveal Melanoma With Different Cytogenetical Characteristics . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3411.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To characterize the expression of the p53 apoptosis effector PERP, identified by microarray–based profiling as a putative molecular determinant of aggressiveness in choroidal melanoma, in relation to cytogenetical characteristics of these tumors. Methods: Transcriptional level of PERP gene was quantitated by real–time RT–PCR using SYBR–Green incorporation in choroidal melanoma specimens with known chromosome 3 and 8 cytogenetical characteristics. Gene–specific primers and a probe of 120 bp were used for quantification. Amplification in similar conditions of a non–changing gene was performed as a normalizing control. Protein level was assessed with a polyclonal anti–PERP antibody by Western blotting of tumor lysates and immunohistochemistry, using standard protocols. Results: PERP immunoreactivity of varying intensities was detected in paraffin–embedded tumor specimens, with a uniform distribution in both spindle and epithelioid–type tumor cells and in some endothelial cells in the tumor. PERP mRNA level appeared significantly downregulated in monosomy 3 tumors compared with the level detected in disomy 3 tumors. Furthermore, Western blot analysis of tumor homogenates indicated a reduced level of the 21kDa form of the PERP protein in monosomy 3 versus disomy 3 choroidal melanomas. Conclusions: Our findings suggest that PERP, a p53 target gene, may play a role in uveal melanoma pathogenesis and that its downregulation/loss of function is particularly relevant to the aggressive type of this tumor by specifically impairing apoptosis and thus promoting tumor progression.
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