Effects of Photons Irradiation on 18F-FET and 18F-DOPA Uptake by T98G Glioblastoma Cells

• Published in: Frontiers in neuroscience Vol. 14; p. 589924
• Main Authors: Pasi, Francesca, Persico, Marco G., Marenco, Manuela, Vigorito, Martina, Facoetti, Angelica, Hodolic, Marina, Nano, Rosanna, Cavenaghi, Giorgio, Lodola, Lorenzo, Aprile, Carlo
• Format: Journal Article
• Language: English
• Published: Lausanne Frontiers Research Foundation 13.11.2020; Frontiers Media S.A
• Subjects: 18F-DOPA; 18F-FET; Brain cancer; Brain research; Brain tumors; Cell culture; Cell viability; Differential diagnosis; Dihydroxyphenylalanine; Glioblastoma; Glioblastoma cells; Inflammation; Magnetic resonance imaging; Medical prognosis; Metabolic pathways; Metabolism; Neuroscience; Pharmaceuticals; photon irradiation; Photons; Positron emission tomography; Radiation; Radiation therapy; Radioactive tracers; Radioisotopes; radionecrosis; T98G cells; Tumors; St Louis Missouri; United States > US; Italy
• ISSN: 1662-453X; 1662-4548; 1662-453X
• DOI: 10.3389/fnins.2020.589924

The differential diagnosis between brain tumors recurrence and early neuroinflammation or late radionecrosis is still an unsolved problem. The new emerging MRI, CT, and PET diagnostic modalities still lack sufficient accuracy. In the last years, a great effort has been made to develop radiotracers able to detect specific altered metabolic pathways or tumour receptor markers. Our research project aims to evaluate irradiation effects on radiopharmaceutical uptake and compare the kinetic of the fluorinate tracers. T98G glioblastoma cells were irradiated at doses of 2 Gy, 10 Gy and 20 Gy with photons and 18F-DOPA and 18F-FET tracer uptake was evaluated. Activity and cell viability at different incubation times were measured. FET and F-DOPA are accumulated via the LAT1 transporter, but F-DOPA is further incorporated while FET is not metabolized. Therefore time-activity curves (TAC) tend to plateau with F-DOPA and to a rapid wash-out with FET. After irradiation F-DOPA TAC resembles the FET pattern. 18F-DOPA activity peak we observed at 20 min might be fictitious, because earlier time points have not been evaluated and it cannot be excluded higher activity peak before 20 min. In addition, the activity retained in the irradiated cells remains higher in comparison to the sham ones at all time points investigated. This aspect is similar in the 18F-FET TAC but less evident. Therefore, we can hypothesize the presence of a second intracellular compartment in addition to the aminoacidic pool one governed by LAT-1 which could explain the progressive accumulation of 18F-DOPA in unirradiated cells.