Transcript Heterogeneity in Pancreatic Cancer Revealed by Microarray Expression Profiling Derived from EUS-FNA Tissue

Abstract

Transcript Heterogeneity in Pancreatic Cancer Revealed by Microarray Expression Profiling Derived from EUS-FNA Tissue Shiro Urayama, Albert Truong Purpose: Previously we have reported the feasibility of expression profiling using the endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) specimen. In this study, we have investigated whether transcript expression heterogeneity were evident in the tissue specimen obtained. Methods: After obtaining IRB approval for human tissue specimen usage, aspirated pancreatic sample obtained during EUS-FNA on pancreatic cancer patients was immediately placed in RNA stabilizer and subsequently stored in 808C freezer. Total RNAwas extracted per standard fashion and cDNA was constructed using T7 promoter-flanked oligo (dT) primer, reverse transcriptase, and DNA polymerase, followed by in vitro transcription. Second round amplificationwas performed on the product to obtain adequate amplified RNA for cDNA microarray analysis. Amplified RNA from commercially available human pancreatic adenocarcinoma cell lines were also synthesized in a similar fashion and expression analysis performed on the arrays. Results: Total of 10 patients with diagnosis of pancreatic adenocarcinoma were included. Three human pancreatic cancer cell lines were used. The yield of the amplified RNA ranged from 2 to 20 ug from the tissue specimen. The purity of the yield was adequate (A260/A280>1.8) per spectrophotometric measurement. Cancer pathway specific gene array (containing 96 genes representative of 15 signal transduction pathways involved in oncogenesis) was used and revealed heterogeneity of the expression profiles among pancreatic cancer patients and human pancreatic cancer cell lines. Conclusions: Expression profiling using EUSFNA samples reveal transcript heterogeneity among the pancreatic adenocarcinoma tissues and cell lines. This information warrants further study and opens a potential for further tumor characterization which may lead to targetted therapies for pancreatic cancer.