Copy number gain of chromosome 3q is a recurrent event in patients with intraductal papillary mucinous neoplasm (IPMN) associated with disease progression

Abstract

Background: Intraductal papillary mucinous neoplasm (IPMN) is the most common cystic preneoplastic lesion of pancreatic cancer. We used an approach coupling high resolution cytogenetic analysis (Affymetrix Oncoscan FFPE Array) with clinically-oriented bioinformatic interpretation of data to understand the most relevant alterations of precursor lesions at different stages to identify new diagnostic markers. Results: We identified multiple copy number alterations, particularly in lesions with severe dysplasia, with 7 IPMN with low-intermediate dysplasia carrying a nearly normal karyotype and 13 IPMN with complex Karyotype (> 4 alterations), showing high grade dysplasia. A specific gain of chromosome arm 3q was found in IPMN with complex Karyotype (92%). This gain of 3q is particularly interesting for the presence of oncogenes such as PIK3CA, GATA2 and TERC that are part of pathways that deregulate cell growth and promote disease progression. Quantitative PCR and FISH analysis confirmed the data. Further demonstration of the overexpression of the PIK3CA gene supports the identification of this alteration as a possible biomarker in the early identification of patients with IPMN at higher risk for disease progression. Materials and methods: High resolution cytogenetic analysis was performed in 20 formalin fixed paraffin embedded samples of IPMN by Oncoscan FFPE assay. Results were validated by qPCR and FISH analysis. Conclusions: The identification of these markers at an early stage of disease onset could help to identify patients at risk for cancer progression and new candidates for a more specific targeted therapy.