Gene Expression Changes Associated with the Progression of Intraductal Papillary Mucinous Neoplasms

Purpose: The diagnosis of high grade intraductal papillary mucinous neoplasm (IPMN) is difficult to distinguish from low grade IPMN. The aim of this study was to identify potential markers for the discrimination of high grade and invasive IPMN from low and moderate grade IPMN. Experimental Design: Laser capture microdissection was used to isolate distinct foci of low grade, moderate grade, high grade, and invasive IPMN from paraffin embedded archival tissue from 14 patients who underwent resection for IPMN. Most samples included multiple grades in the same specimen. Affymetrix Human Exon microarrays were used for gene expression analysis to compare low and moderate grade (LMD) IPMN to high grade and invasive (HgInv) IPMN. Results: When comparing samples of LMD dysplasia (n=15) to those demonstrating HgInv (n=13), 62 genes were identified as showing significant changes in expression (p≤0.05 and a 2-fold cutoff), with up-regulation of 41 in HgInv IPMN and down-regulation in 21. Changes in gene expression are associated with biological processes related to malignant behavior including cell motion, cell proliferation, response to hypoxia, and epithelial to mesenchymal transition. Hierarchical clustering analysis demonstrated the ability of these 62 differentially expressed genes to distinguish between LMD and HgInv samples. In addition, altered signaling in several TGFβ-related pathways was exhibited in the progression of IPMN to malignancy. Conclusions: This study identifies a set genes associated with the progression of IPMN to malignancy. These genes are potential markers that could be used to identify IPMN requiring surgical resection. Using laser capture microdissection, distinct foci of low (n=10), moderate (n=5), and high grade dysplasia (n=6) as well as invasive carcinoma (n=7) were isolated from paraffin embedded archival tissue of 14 patients who underwent resection for IPMN. Gene expression data from Affymetrix Human Exon 1.0ST microarrays was utilized to compare low and moderate grade IPMN to high and invasive IPMN.

研究目的：高级别导管内乳头状黏液性肿瘤（intraductal papillary mucinous neoplasm, IPMN）的诊断与低级别IPMN难以鉴别。本研究旨在筛选可用于区分高、侵袭性IPMN与低、中级别IPMN的潜在标志物。
实验设计：采用激光捕获显微切割（Laser capture microdissection）从14例接受IPMN切除术患者的石蜡包埋存档组织中，分离出低级别、中级别、高级别及侵袭性IPMN的独立病灶。多数样本的同一标本中包含多个病变级别。采用Affymetrix人类外显子微阵列（Affymetrix Human Exon microarrays）进行基因表达分析，对比低、中级别（low and moderate grade, LMD）IPMN与高、侵袭性（high grade and invasive, HgInv）IPMN的基因表达差异。
结果：将15例LMD异型增生样本与13例HgInv样本进行对比时，共鉴定出62个表达存在显著差异的基因（p≤0.05且变化倍数≥2倍），其中HgInv IPMN中41个基因上调、21个基因下调。基因表达变化与恶性行为相关的生物学过程密切相关，包括细胞运动、细胞增殖、缺氧应答及上皮间质转化（epithelial-mesenchymal transition, EMT）。分层聚类分析显示，这62个差异表达基因可有效区分LMD与HgInv样本。此外，IPMN进展为恶性过程中，多条转化生长因子β（transforming growth factor-β, TGFβ）相关通路的信号转导发生异常。
结论：本研究鉴定出一组与IPMN恶性进展相关的基因，这些基因可作为潜在标志物，用于识别需接受手术切除的IPMN患者。本研究通过激光捕获显微切割，从14例IPMN切除术患者的石蜡包埋存档组织中，分离出低级别异型增生病灶10个、中级别异型增生病灶5个、高级别异型增生病灶6个及侵袭性癌病灶7个。采用Affymetrix Human Exon 1.0ST微阵列的基因表达数据，对比低、中级别IPMN与高、侵袭性IPMN的表达差异。