MicroRNA expression profiling on formalin-fixed paraffin-embedded (FFPE) tissue blocks of human adrenal pheochromocytomas

MicroRNAs are involved in the pathogenesis of several tumors, however, there have been no data on microRNA expression in pheochromocytomas to date. In this study we have performed microRNA expression profiling in sporadic benign, hereditary benign (multiplex endocrine neoplasia type 2-related and von Hippel-Lindau syndrome-related pheochromocytomas), and sporadic recurring adrenomedullary tumors. Due to the rarity of these neoplasms, the retrieval of sufficient quantities of fresh or immediately snap frozen tumor samples is difficult, therefore the applicability of formalin-fixed paraffin-embedded tissue samples for the analysis of microRNA expression in pheochromocytomas was examined. In this study microRNA expression pattern of sporadic benign, sporadic recurring, MEN2-related and VHL-related hereditary adrenal pheochromocytomas has been reported. For microRNA expression profiling, total RNA was extracted from formalin-fixed paraffin-embedded (FFPE) tissue blocks. Biological replicates: 6 sporadic benign, 5 sporadic recurring, 5 MEN2-related and 5 VHL-related pheochromocytoma FFPE tissues has been investigated (n=21). To prove the applicability of FFPE blocks for microRNA microarray analysis, the microRNA expression data of three matched frozen and FFPE pheochromocytoma samples derived from the same patients were compared. MicroRNA expression analysis of 21 FFPE and 3 frozen samples was performed on Agilent Human miRNA Microarray Rel12.0 (v3.0) (8x15k) containing probes corresponding to 866 human and 89 human viral miRs.

微小RNA（microRNAs）参与多种肿瘤的发病进程，但截至目前尚无针对嗜铬细胞瘤微小RNA表达特征的相关研究数据。本研究针对散发性良性、遗传性良性（包括多发性内分泌腺瘤2型（MEN2）相关及希佩尔-林道综合征（VHL）相关嗜铬细胞瘤）以及散发性复发性肾上腺髓质肿瘤开展了微小RNA表达谱分析。由于此类肿瘤较为罕见，获取足量新鲜或即刻快速冷冻的肿瘤样本存在难度，因此本研究对福尔马林固定石蜡包埋（FFPE）组织样本用于嗜铬细胞瘤微小RNA表达分析的适用性进行了验证。本研究现已报道散发性良性、散发性复发性、MEN2相关及VHL相关遗传性肾上腺嗜铬细胞瘤的微小RNA表达特征。针对微小RNA表达谱分析，本研究从福尔马林固定石蜡包埋组织块中提取总RNA。本次研究的生物学重复样本设置如下：共计分析21例FFPE组织样本，其中6例散发性良性嗜铬细胞瘤、5例散发性复发性嗜铬细胞瘤、5例MEN2相关嗜铬细胞瘤及5例VHL相关嗜铬细胞瘤。为验证FFPE组织块用于微小RNA微阵列分析的适用性，本研究对3例匹配的同一患者来源的冷冻及FFPE嗜铬细胞瘤样本的微小RNA表达数据进行了对比分析。本研究采用安捷伦（Agilent）人类微小RNA微阵列Rel12.0（v3.0）（8×15k）对21例FFPE样本及3例冷冻样本开展微小RNA表达分析，该芯片包含对应866种人类微小RNA及89种人类病毒微小RNA的探针序列。