Isolation and characterization of differentially expressed genes in human benign insulinomas

Author(s)

Karin Krogh

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2005-02-14

Examining board members

Mari Cleide Sogayar; Pio Colepicolo Neto; Marcel Cerqueira Cesar Machado; Vilma Regina Martins; Geraldo Aleixo da Silva Passos Júnior

• Advisor: Mari Cleide Sogayar

Abstract

Insulinomas are the most common pancreatic endocrine neoplasms, comprising around 17% of all neuroendocrine tumors of the digestive tract. These rare tumors have hypoglycemia as the main clinical manifestation, caused by over secretion of insulin by the tumor. Based on that, the objective of this work is the identification of differentially expressed genes in human benign insulinomas, aiming at the better understanding of the molecular mechanisms of their tumorigenic process and the discovery of new molecular targets for therapeutics. Using the CodeLink bioarrays platform (GE Healthcare) 354 genes upregulated in human benign insulinomas were identified, among which, 16% are involved in cell proliferation. From these genes, 6 were chosen for validation by Real Time PCR, where SPARCL1, PRSS11, STAT4, ECRG4 and ASCL1 were shown to be upregulated in all benign tumors, however the expression difference of IGFALS gene were not statistically significant. Using the RDA (Representational Difference Analysis) methodology, the unknown gene FLJ13072 was shown to be upregulated in benign isulinomas when compared to normal pancreatic islets. The putative protein product from this gene has an helicase domain, being possibly involved in processes like transcription, translation, DNA repair and chromatin remodeling. An important drawback for the study of insulinomas is the lack of human cell lines. Because of that, the establishment of early primary cultures of human insulinomas was initiated, aiming at its use as a cell model for future functional studies of the genes identified. (AU)