MicroRNA Are Differentially Expressed in Appendiceal Versus Ileal Neuroendocrine Tumors
Shaolei Lu, Kelly Cleveland, Shamlal Mangray, Alexander Brodsky, Murray Resnick, Evgeny Yakirevich. Warren Alpert Medical School of Brown University, Providence, RI
Background: Gastrointestinal neuroendocrine tumors (NETs) comprise a heterogenous group of neoplasms with a varying spectrum of aggressiveness. Ileal NETs have greater metastatic potential than appendiceal carcinoids. The role of microRNAs (miRNAs) in tumor growth and progression is an active area of ongoing research; however, miRNA profiles of gastrointestinal NETs have not as yet been elucidated. The goal of this study was to compare the expression of miRNAs in ileal versus appendiceal NETs.
Design: Formalin fixed paraffin embedded tissues from 4 primary ileal NETs and 4 appendiceal NETs were retrieved from the archives of Rhode Island Hospital. The tumor cells were microdissected from 10 mm sections using Arcturus Laser Capture Microdissection. MiRNA was isolated and profiled using Taqman Human miRNA Array cards containing probes for 380 human miRNAs. Bioinformatic mRNA targets of miRNA were generated by Ingenuity Pathway Analysis (IPA). The miRNA candidates were further confirmed using individual miRNA quantitative RT-PCR assays on a new set of 10 ileal and 5 appendiceal NETs. The DAVID web program was used to analyze the functionality of gene groups.
Results: A total of 31 miRNAs were differentially expressed in 4 primary ileal NETs as opposed to 4 appendiceal NETs (P<0.05). All these miRNAs were up-regulated in ileal NETs as compared to appendiceal NETs. In search of their targets, IPA analysis identified 55 mRNAs, each one targeted by 4 or more of 9 miRNAs: miR-194, miR-218, miR-24, miR-30c, miR-26a, miR-28-3p, miR-574-3p, miR-320d, and miR-342-3p. Eight of these 9 miRNAs (except miR-320d) were further validated using quantitative RT-PCR in the same set of tumors studied by the Array cards and in an additional 10 ileal and 5 appendiceal NETs (fold changes from 4.8 to 27.2). Bioinformatic analysis (DAVID) of the 55 mRNAs revealed gene products with functions related to cellular signaling, growth factor binding, ion transportation, and cellular biosynthetic process, and neuron morphogenesis and differentiation.
Conclusions: This study is the first to compare the miRNA profile of ileal and appendiceal NETs. We identified and validated the differential expression of eight miRNAs in ileal as opposed to appendiceal NETs. Further studies will be needed to investigate the role of these novel miRNAs in the biological behavior of ileal NETs.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 85, Monday Morning