Evaluation of [11c]mpc-6827 as a Microtubule Targeting Pet Radiotracer in Cancer Cell Lines

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.

Effect of ethanol and cocaine on [11C]MPC-6827 uptake in SH-SY5Y cells

“…The lowered radioactive uptake in EtOH-and cocaine-treated SH-SY5Y cells indicates that [ 11 C]MPC-6827 uptake correlate well with observed bound/free tubulin changes and may be tracking free β tubulin units, as both substance treatments decreased free tubulin content in the same cells. MTAs are categorized as either stabilizing agents (paclitaxel, laulimalide, and EpoD) [38][39][40], which favor polymerization of tubulin units and inhibit cell proliferation, or destabilizing agents (vinblastine and mertasine) [41][42][43][44], which increase free/unbound tubulins and promote apoptotic cell death. To distinguish their effect on MT integrity in SH-SY5Y cells, we performed the same tubulin-based western blot assays on paclitaxel-and vinblastine-treated cells [45].…”

Ethanol and cocaine increases microtubule stability and decreases [11C]MPC-6827 uptake in SH-SY5Y cells

“…MTAs are categorized as either stabilizing agents (paclitaxel, laulimalide, and EpoD), [34][35][36] which favor polymerization of tubulin units and inhibit cell proliferation, or destabilizing agents (vinblastine and mertasine), [37][38][39][40] which increase free/unbound tubulins and promote apoptotic cell death. To distinguish their effect on MT integrity in SH-SY5Y cells, we performed the same tubulin-based western blot assays on paclitaxel-and vinblastine-treated cells.…”