Olfactory Receptor 51E1 is a Novel Potential Tissue Biomarker for the Diagnosis and Prognosis of Small Intestine Neuroendocrine Tumors.

Introduction: Small intestine neuroendocrine tumors (SI-NETs) get late diagnosis. We discovered the olfactory receptor 51El (OR51E1) as a potential target to develop as a novel biomarker. Aim(s): To develop OR51E1 as a SI-NET novel tissue biomarker for diagnostics and prognostics. Materials and methods: OR51El coding sequence was cloned from SI-NET patient specimens and NET cell lines. OR51E1 expression was analyzed by quantitative-real-time-PCR (QRT-PCR) on human normal and NET cell lines; normal liver tissue and normal hepatic cells; microdissected SI-NET cells and stroma cells. OR51El protein expression was analyzed by immunohistochemistry (IHC) on SI-NET slides and tissue microarray analysis (TMA). Furthermore, a new polyclonal antibody was developed. Results: OR51E1 coding sequence is identical in NETs and normal tissue. NET cell lines express OR51E1 at different levels. QRT-PCR analysis shows higher OR51E1 expression in microdissected SI-NET cells than do stroma cells. IHC and TMA show OR51E1 expression in SI-NETs and other cancer tissues. We detected OR51E1 protein in normal liver tissue. However, QRTPCR did not detect OR51E 1 expression in total RNA from different normal hepatic cells and normal liver tissue. Conclusion: OR51E1 is a potential biomarker for the diagnosis and progression of SI-NETs. However, further analysis and production of specific antibodies are ongoing to develop OR51EI as a new SI-NET biomarker. [ABSTRACT FROM AUTHOR]