EVALUATION OF [11C]MPC-6827 AS A MICROTUBULE TARGETING PET RADIOTRACER IN CANCER CELL LINES

J S Dileep Kumar,Kiran Kumar Solingapuram Sai,Steven J Kridel,Naresh Damuka,J John Mann,Jaya Prabhakaran,Akiva Mintz,Justin W Hines

doi:10.22159/ijpps.2020v12i1.35657

Abstract

Objective: The objective of this study was to evaluate the uptake and specificity of [11C]MPC-6827, a MT targeted PET ligand in prostate, glioblastoma and breast cancer cells. Methods: [11C]MPC-6827 was synthesized by reacting corresponding desmethyl precursors with [11C]CH3I in a GE-FX2MeI/FX2M radiochemistry module. In vitro binding of [11C]MPC-6827 was performed in breast cancer MDA-MB-231, glioblastoma (GBM) patient-derived tumor (GBM-PDX), GBM U251 and prostate cancer 3 (PC3) cell lines at 37 °C in quadruplicate at 5, 15, 30, 60, and 90 minute incubation time. The nonspecific bindings were determined by incubation with unlabeled microtubule targeting agents MPC-6827, HD-800, colchicine, paclitaxel and docetaxel (5.0 mM). Results: [11C]MPC-6827 provided the highest binding in the breast cancer cell, MDA-MB-231, among all the cells studied, with 90% specific binding. [11C]MPC-6827 binds to glioblastoma PDX and U251 cells with ~50% and 40% specific binding, whereas, prostate cancer cell line, PC3 cells showed 40% specific binding. [11C]MPC-6827 also exhibits binding to the taxane and colchicine binding sites of MTs, in MDA-MB-231 cells. Conclusion: These data indicate that [11C]MPC-6827 can be a promising PET radiotracer for preclinical imaging of the brain and peripheral cancers.

Highlights

Microtubules (MTs) are one of the major components of cytoskeletal polymers, which are found in all eukaryotic cell
Biochemical activities of MTs are regulated by free tubulin dimers, microtubule-stabilizing proteins (MSP), microtubule destabilizing or depolymerizing proteins, microtubule-associated proteins (MAP), and post-translational modification (PTM) of tubulin [5,6,7,8]
Mutations associated with spindle disorientation through an increase in MT dynamics lead to an imbalance causing reduced or excessive cell proliferation that can result in cancer, birth disorders and brain diseases [12,13,14,15,16,17]

Summary

Introduction

Microtubules (MTs) are one of the major components of cytoskeletal polymers, which are found in all eukaryotic cell. We report the in vitro evaluation of [11C]MPC-6827 in triple-negative breast cancer MDA-MB-231, glioblastoma (GBM) patient-derived tumor (GBM-PDX), GBM U251 and prostate cancer-3 (PC3) cell lines. The blocking solution of MPC6827 [34], HD-800 [35], docetaxel, paclitaxel, and colchicine (Sigma Aldrich, MO) at a concentration of 5.0 μM in the same culture media was freshly prepared on the same day of cell assay. The assay buffer was formulated with radiotracer by adding 20 μl/ml of [11C]MPC-6827, at a concentration of 74 kBq/ml to each block and non-block condition.

Results

Conclusion