Abstract
7
Purpose: Overexpression of CD146 in various malignant tumors has been considered as a hallmark of cancer and related with tumor progression and poor outcome. Imaging of the differential expression of CD146 in breast cancer provided a noninvasive method in the diagnosis. We developed a 64Cu-labeled CD146-specific monoclonal antibody (YY146) and evaluated its application for noninvasive imaging of the differential expression of CD146 in murine breast cancer models.
Methods: YY146 was conjugated to 1,4,7-triazacyclononane-triacetic acid (NOTA) and then was radiolabeled with 64Cu using routine methods. CD146 expression was screened in four human breast cancer cell lines (MB-231, MB-435, MCF-7 and SKBR3) using western blot. Flow cytometry was further used to evaluate the binding ability of YY146 in vitro. The serial immunoPET imaging and semi-quantitative analysis was used to evaluate the in vivo uptake of 64Cu-NOTA-YY146 in breast tumor-bearing mice during 48 h post intravenous injection. Biodistribution and immunohistochemistry studies were performed for validation.
Results: Western blot results displayed that MB-435 cell line had the highest level of expression of CD146 while MCF-7 had the lowest expression of CD146. Flow cytometry verified that both of NOTA-conjugated YY146 and YY146 could bind with MB-435 cells strongly. PET imaging displayed that MB-435 bearing tumors could be visualized clearly with high radioactive uptake after the injection of 64Cu-NOTA-YY146. But in contrast, MCF-7 bearing tumor showed near background uptake in vivo. The tumor uptake of 64Cu-NOTA-YY146 was peaking at 16.5 ± 2.8 %ID/g for the MB-435 model while that was at 3.6 ±1.2 %ID/g for the MCF-7 model at 48 h after injection (n=4), via PET ROI analysis. Ex vivo biodistribution confirmed the results of PET data. Histological staining verified the high expression of CD146 in MB-435 and low expression in MCF-7.
Conclusions: The tumor uptake of 64Cu-NOTA-YY146 shows a strong correlation of CD146 expression in breast cancer models. 64Cu-NOTA-YY146 might be potentially used for imaging and monitoring therapeutic response in breast cancer in the future.