5-ALA Fluorescence in Native Pituitary Adenoma Cell Lines: Resection Control and Basis for Photodynamic Therapy (PDT)?

Andrei Nemes,Volker Senner,Daniel Prevedello,Thomas Fortmann,Antonio Santacroce,Burkhard Greve,Christian Ewelt,Stephan Poeschke,Walter Stummer,Nima Etminan

doi:10.1371/journal.pone.0161364

Andrei Nemes, Volker Senner + Show 8 more

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https://doi.org/10.1371/journal.pone.0161364

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Journal: PloS one	Publication Date: Sep 1, 2016
Citations: 15	License type: CC BY 4.0

Affiliation: University Hospital Münster, Neurological Surgery

Abstract

Objective: Pituitary adenomas (PA), especially invasive ones, are often not completely resectable. Usage of 5-aminolevulinic acid (5-ALA) for fluorescence guided surgery could improve the rate of total resection and, additionally, open the doors for photodynamic therapy (PDT) in case of unresectable or partially resected PAs. The aim of this study was to investigate the uptake of 5-ALA and the effect of 5-ALA based PDT in cell lines. Methods: GH3 and AtT-20 cell lines were incubated with different concentrations of 5-ALA, protoporphyrin IX (PPIX) fluorescence was measured by flow cytometry and fluorescencespectrometry. WST-1 assays were performed to determine the surviving fraction of cells after PDT. PPIX fluorescence intensities and PDT effect of the pituitary adenoma cells were compared to U373MG, a well-known glioblastoma cell line. Results: Both cell lines showed a 5-ALA dependent intracellular PPIX fluorescence. Significant differences after 24hrs of incubation were observed in AtT-20 cells in comparison to GH3. Regardless of the incubation or metabolism time, there was a proliferation inhibiting effect after PDT, with no statistical significance. Conclusion: Since GH3 cells showed a heterogenous uptake of 5-ALA in the flow cytometry profile, but not constantly high concentrations they might have a 5-ALA efflux mechanism, which still needs to be determined. In the case of AtT-20, the cells might need a longer time for the uptake due to their size or slow metabolism. We showed that the different cell lines have different uptake and metabolism mechanisms, which needs to be further investigated. The general uptake of 5-ALA allows the possibility of resection control and PDT for pituitary adenomas. But, the role of PDT for unresectable pituitary adenomas deserves further investigations.

Highlights

Pituitary adenomas have an incidence of 10–12% of all intracranial tumors and are mostly benign tumors of the anterior pituitary gland [1]
Under monolayer culture conditions and performing the experiments at atmospheric pressure the limiting factor is the intracellular protoporphyrin IX (PPIX) accumulation. We analyzed this by flow cytometric and spectrofluorimetrical measurements in two pituitary adenoma cell lines: GH3 and AtT-20 and the glioblastoma cell line U373MG
The glioblastoma cell line U373 MG is known for strong 5-aminolevulinic acid (5-ALA) uptake and metabolism to PPIX and showed a good photodynamic reaction upon 5-ALA based photodynamic therapy (PDT) [16,18]

Summary

Introduction

Pituitary adenomas have an incidence of 10–12% of all intracranial tumors and are mostly benign tumors of the anterior pituitary gland [1]. While the majority of pituitary tumors include slow growing, non-metastasizing adenomas, approximately one third will become invasive and a very small proportion (0.1%) will become malignant [2]. Many factors influence the proliferation of pituitary adenomas, such as angiogenesis, apoptosis, growth factors, oncogenes, tumor suppressor genes, and hormone receptors [2,3]. Gross total resection especially in invasive adenomas is not always possible. Adjuvant treatment modalities, such as dose fractionated radiotherapy, specific drug therapy or, in the last ten years, radiosurgery are required [6]

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