Detection and Differentiation of Breast Cancer Sub-Types using a cPLA2\u03b1 Activatable Fluorophore

Michael G Chiorazzo,Anatoliy V Popov,E James Delikatny,Hanna Maja Tunset,Berit Johansen,Siver Moestue

doi:10.1038/s41598-019-41626-y

Abstract

Cytosolic phospholipase A2α (cPLA2α) has been shown to be elevated in breast cancer and is a potential biomarker in the differentiation of molecular sub-types. Using a cPLA2α activatable fluorophore, DDAO arachidonate, we explore its ability to function as a contrast agent in fluorescence-guided surgery. In cell lines ranging in cPLA2α expression and representing varying breast cancer sub-types, we show DDAO arachidonate activates with a high correlation to cPLA2α expression level. Using a control probe, DDAO palmitate, in addition to cPLA2α inhibition and genetic knockdown, we show that this activation is a result of cPLA2α activity. In mouse models, using an ex vivo tumor painting technique, we show that DDAO arachidonate activates to a high degree in basal-like versus luminal-like breast tumors and healthy mammary tissue. Finally, we show that using an in vivo model, orthotopic basal-like tumors give significantly high probe activation compared to healthy mammary fat pads and surrounding tissue. Together we conclude that cPLA2α activatable fluorophores such as DDAO arachidonate may serve as a useful contrast agent for the visualization of tumor margins in the fluorescence-guided surgery of basal-like breast cancer.

Highlights

Several fluorescent contrast agents have been explored for their potential clinical use as intraoperative agents including indocyanine green, fluorescein, and methylene blue[2,3,7,8,15]
Discussion Cytosolic phospholipase A2α (cPLA2α) has recently been shown to have an important role in breast cancer progression and to be a potential therapeutic target in basal-like breast cancer. cPLA2α expression levels have been shown to correlate with molecular sub-type, being highest in basal-like and lowest in luminal-like carcinoma36,37. cPLA2α is is a powerful biomarker for the detection of aggressive, basal-like breast cancer
Using a newly developed, red fluorescent, cPLA2α targeted, activatable fluorophore (DDAO arachidonate) and control (DDAO palmitate) we sought to exploit this biomarker for the detection and differentiation of breast cancer in cultured cells and tumors

Summary

Introduction

Several fluorescent contrast agents have been explored for their potential clinical use as intraoperative agents including indocyanine green, fluorescein, and methylene blue[2,3,7,8,15]. These agents rely on the Enhanced Permeability and Retention (EPR) effect, a characteristic associated with disordered tumor vasculature which results in increased accumulation and retention of high molecular weight particles[16]. We explore the use of DDAO arachidonate to detect cPLA2α activity in several breast cancer sub-types both in cells and in vivo mouse models

Methods

Results

Conclusion