Somatostatin Analogs and mTOR Inhibitors as Radioprotectors or Radiosensitizers in Neuroendocrine Tumor Cells

#2291

Introduction: Neuroendocrine tumors (NETs) express somatostatin receptors that are currently utilized for diagnostic and therapeutic approaches. For peptide receptor radionuclide therapy (PRRT), somatostatin analogs are coupled to radionuclides like 90Y or 177Lu, which after injection are bound and taken up specifically by NETs. One hypothesis potentially explaining the discrepancies between expected result and observed outcome of PRRT might be that somatostatin analogs induce a G1 arrest in NET cells, thereby rendering them radioresistant.

Aim(s): Identify possible mediators and mechanism contributing to radiosensitivity towards PRRT.

Materials and methods: To investigate this, NET cell lines were incubated with or without agonists and exposed to different radiation doses from a 137Cs source between 0 and 50 Gy. Cells were harvested at distinct timepoints, stained with propidium iodide and the cell cycle distribution was assessed by FACS analysis, proliferation and vitality by cell counting, clonogenic assay and AlamarBlue assay.

Conference: 15th Annual ENETSConcerence (2018)

Presenting Author: Grötzinger C

Authors: Grötzinger C, Exner S, Prasad V, Erdmann S, Wiedenmann B,

Keywords: PRRT,

Somatostatin Analogs and mTOR Inhibitors as Radioprotectors or Radiosensitizers in Neuroendocrine Tumor Cells

#1506

Introduction: PRRT can deliver radiation doses of up to 250 Gy to the tumors. Nevertheless, complete remission is extremely rare, compared to similar radiotherapies for thyroid cancer and non-Hodgkin lymphoma.

Aim(s): One hypothesis potentially explaining the discrepancies between expected result and observed outcome of PRRT might be that somatostatin analogs induce a G1 arrest in NET cells, thereby rendering them radioresistant. Other medical therapeutics like mTOR inhibitors may also contribute to radiosensitivity towards PRRT.

Materials and methods: To investigate this, NET cell lines were incubated with or without agonists and exposed to different radiation doses from a 137Cs source between 0 and 50 Gy. Cells were harvested at distinct timepoints, stained with propidium iodide and the cell cycle distribution was assessed by FACS analysis. Proliferation, vitality and mitochondrial activity were assessed using cell counting, clonogenic assay and Alamar Blue assay, respectively.

Conference: 13th Annual ENETSConcerence (2016)

Presenting Author:

Authors: Exner S, Erdmann S, Wiedenmann B, Prasad V, Grötzinger C,

Keywords: PRRT,