The Synthesis and Evaluations of the (6 8) Ga-Lissamine Rhodamine B (LRB) as a New Radiotracer for Imaging Tumors by Positron Emission Tomography.

Xuena Li,Bulin Du,Yaming Li,Na Li,Yafu Yin

doi:10.1155/2016/8549635

Abstract

Purpose. The aim of this study is to synthesize and evaluate 68Ga-labeled Lissamine Rhodamine B (LRB) as a new radiotracer for imaging MDA-MB-231 and MCF-7 cells induced tumor mice by positron emission tomography (PET). Methods. Firstly, we performed the radio synthesis and microPET imaging of 68Ga(DOTA-LRB) in athymic nude mice bearing MDA-MB-231 and MCF-7 human breast cancer xenografts. Additionally, the evaluations of 18F-fluorodeoxyglucose (FDG), as a glucose metabolism radiotracer for imaging tumors in the same xenografts, have been conducted as a comparison. Results. The radiochemical purity of 68Ga(DOTA-LRB) was >95%. MicroPET dynamic imaging revealed that the uptake of 68Ga(DOTA-LRB) was mainly in normal organs, such as kidney, heart, liver, and brain and mainly excreted from kidney. The MDA-MB-231 and MCF-7 tumors were not clearly visible in PET images at 5, 15, 30, 40, 50, and 60 min after injection of 68Ga(DOTA-LRB). The tumor uptake values of 18F-FDG were 3.79 ± 0.57 and 1.93 ± 0.48%ID/g in MDA-MB-231 and MCF-7 tumor xenografts, respectively. Conclusions. 68Ga(DOTA-LRB) can be easily synthesized with high radiochemical purity and stability; however, it may be not an ideal PET radiotracer for imaging of MDR-positive tumors.

Highlights

Tumor growth depends on the energy metabolism of the supply, and the biological energy of tumor has received much attention in recent years [1, 2]
Active glucose uptake by cancer cells constitutes the basis for 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG PET), an imaging technology commonly used in cancer diagnosis
The MDA-MB-231 tumors were not clearly visible with high contrast at all the time points examined for 68Ga(DOTA-Lissamine Rhodamine B (LRB)) PET imaging

Summary

Introduction

Tumor growth depends on the energy metabolism of the supply, and the biological energy of tumor has received much attention in recent years [1, 2]. A metabolic shift from oxidative phosphorylation in the mitochondria to glycolysis in cancer was first described about 80 years ago by Warburg [3]. Increased glucose metabolism is an important feature of cancer [4]. Active glucose uptake by cancer cells constitutes the basis for 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG PET), an imaging technology commonly used in cancer diagnosis. The reverse Warburg effect was recently found in a human breast cancer model [5,6,7]. The researchers found that breast cancer cells showed a significant increase activity in mitochondria [8]. The development of molecular imaging probes targeting tumor mitochondria is very limited

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