Impact of Ischemia and Procurement Conditions on Gene Expression in Renal Cell Carcinoma

Purpose: Previous studies have shown that ischemia alters gene expression in normal and malignant tissues. There are no studies that evaluated effects of ischemia in renal tumors. This study examines the impact of ischemia and tissue procurement conditions on RNA integrity and gene expression in renal cell carcinoma. Experimental Design: Ten renal tumors were resected without renal hilar clamping from 10 patients with renal clear cell carcinoma. Immediately after tumor resection, a piece of tumor was snap frozen. Remainingtumorsampleswerestoredat4C,22C,and37Candfrozenat5,30,60,120,and240minutes. Histopathologic evaluation was conducted on all tissue samples, and only those with greater than 80% tumorwereselectedforfurtheranalysis.RNAintegritywasconfirmedbyelectropherogramsandquantitated using RNA integrity number index. Altered gene expression was assessed by paired, two-sample t test between the zero time point and aliquots from various conditions obtained from the same tumor. Results: One hundred and forty microarrays were conducted. Some RNA degradation was observed 240 minutes after resection at 37C. The expression of more than 4,000 genes was significantly altered by ischemia times or storage conditions. The greatest gene expression changes were observed with longer ischemia time and warmer tissue procurement conditions. Conclusion:RNAfromkidneycancerremainsintactforupto4hourspostsurgicalresectionregardlessof storage conditions. Despite excellent RNA preservation, time after resection and procurement conditions significantly influence gene expression profiles. Meticulous attention to preacquisition variables is of paramount importance for accurate tumor profiling. Clin Cancer Res; 19(1); 42–49. � 2012 AACR.