Multicomponent Analysis of the Pancreatic Adenocarcinoma Progression Model Using a Pancreatic Intraepithelial Neoplasia Tissue Microarray

Abstract

A multistep model for pancreatic adenocarcinoma has been proposed recently. In this model, well-defined, noninvasive ductal lesions are recognized as precursors of invasive cancer and have been classified under the nomenclature of pancreatic intraepithelial neoplasia, or PanIN. Increasing evidence suggests that PanINs represent true neoplasms of the pancreatic ductal epithelium, accumulating histologic and genetic abnormalities in their progression toward invasive cancer. We have constructed a tissue microarray containing 55 PanIN lesions of all histologic grades in order to perform a multicomponent analysis of the pancreatic adenocarcinoma progression model. The protein products of 14 genes encompassing a variety of functional classes, such as tumor suppressor genes (p53, Smad4/Dpc4), oncogenes (beta-catenin), cell cycle antigens (p16, cyclin D1), proliferation antigens (Ki-67, topoisomerase II alpha), and epithelial apomucins (MUC1, MUC2, MUC5), as well as "novel" genes described as differentially up-regulated in invasive pancreas cancer by global microarray expression analysis (mesothelin, prostate stem cell antigen, fascin, and 14-3-3varsigma), were analyzed by immunohistochemistry on the PanIN tissue microarray. Comparison of the results from the current study with previously published data performed on routine histologic sections of PanINs demonstrates that tissue microarrays are a valid platform for molecular analysis not only of invasive cancers but of precursor lesions as well. In addition, this study demonstrates that molecular abnormalities in PanINs are not random but can usually be stratified into "early" changes (e.g., expression of MUC5 and prostate stem antigen, or loss of p16), "intermediate" changes (e.g., expression of cyclin D1), and "late" changes (e.g., expression of p53, proliferation antigens, MUC1, mesothelin, and 14-3-3varsigma, or loss of Smad4/Dpc4). Understanding the molecular pathogenesis of precursor lesions of invasive pancreatic adenocarcinomas using a high-throughput tissue microarray-based approach is a valuable adjunct to designing rational strategies for early detection of this lethal neoplasm.

Fascin overexpression in intraductal papillary mucinous neoplasms (adenomas, borderline neoplasms, and carcinomas) of the pancreas, correlated with increased histological grade

“…Immunohistochemical studies then confirmed fascin overexpression, not only in infiltrating ductal adenocarcinomas 28,30,31 but also in PanINs. 29,30 The fact that PanINs show fascin upregulation correlated with histological grade increased our interest in fascin expression in IPMNs, because PanINs and IPMNs share the following fundamental characteristics: 5,6 inherently intraductal; composed predominantly of columnar, mucin-producing cells that may grow in a flat configuration or may produce papillae; exhibit a range of cytologic and architectural atypia (mild, moderate and severe); recognized as precursors to Fascin expression in IPMNs of the pancreas H Yamaguchi et al invasive adenocarcinoma; and sequentially accumulate similar genetic alterations with increasing cytoarchitectural atypia. [43][44][45] We showed that fascin overexpression in IPMNs was correlated with increased histological grade by immunohistochemical analysis, followed by a supporting molecular experiment that showed upregulation of fascin mRNA.…”

“…It is required for the formation of actin-based cell-surface protrusions that are essential for cellular migration and cellmatrix adhesion. [15][16][17] In normal epithelial cells, fascin expression is usually absent or very low, but it is significantly upregulated in transformed epithelial cells and several types of human carcinoma such as lung, 18,19 breast, [20][21][22][23] esophagus, 24,25 stomach, 26 colon, 27 pancreas, [28][29][30][31] biliary tract and ampulla, 31,32 ovary, 33 urinary bladder, 34 and skin. 35 Among the above neoplasms, fascin upregulation is most frequently observed in pancreatic infiltrating adenocarcinoma.…”

“…28,30,31 It is interesting that PanIN shows fascin expression despite being an intraepithelial neoplasia. 29,30 In general, in tumors of other organs, expression of fascin is especially strong in areas of infiltration, or is limited to such areas. Fascin expression in IPMN and its relationship with the clinicopathological features remain unclear, though IPMN has much in common with PanIN.…”

Concordant loss of MTAP and p16/CDKN2A expression in pancreatic intraepithelial neoplasia: evidence of homozygous deletion in a noninvasive precursor lesion

“…3 Telomere shortening and activating point mutations in the KRAS2 oncogene occur early in PanIN-1 lesions, the p16INK4A/CDKN2A (henceforth referred to as p16) gene is inactivated in intermediate and late lesions (PanINs 2 and 3), and the TP53, MADH4, and BRCA2 genes are inactivated late, in PanIN-3 lesions. [4][5][6][7][8][9][10] …”

“…3 Telomere shortening and activating point mutations in the KRAS2 oncogene occur early in PanIN-1 lesions, the p16INK4A/CDKN2A (henceforth referred to as p16) gene is inactivated in intermediate and late lesions (PanINs 2 and 3), and the TP53, MADH4, and BRCA2 genes are inactivated late, in PanIN-3 lesions. [4][5][6][7][8][9][10] One of the most important of the genetic alterations in infiltrating adenocarcinoma of the pancreas and in PanIN, as judged by its high prevalence, is inactivation of the p16 gene. The p16 gene is inactivated in 40% of pancreatic cancers by homozygous deletion, in 40% by an intragenic mutation coupled with loss of the second allele, and in 15% by hypermethylation of the p16 gene promoter.…”