Abstract 4918: Modified citrus pectin slows migration of triple negative breast cancer cells in an impedance-based scratch assay
Authors: Zhu Longjing , Chvatal Stacie A. , Hayes Heather B. , Millard Daniel C. , Gomillion Cheryl T. 
Published: September 2020

Abstract
Triple-negative breast cancer (TNBC) is an aggressive breast cancer with a poorer prognosis than other types of breast cancer due to limited therapeutic targets and high risk of metastatic recurrence. Modified Citrus Pectin (MCP), a modified polysaccharide derived from citrus fruit peel, has shown antimetastatic properties in many cancers, including breast cancer. MCP is thought to reduce metastatic potential by inhibiting galectin-3 which may block the “loss of anchorage” phase of metastasis (anoikis). Here we assessed the proliferation and migration of two breast cancer lines: MCF-7, a hormone-receptor positive line, and HCC1806, a TNBC line, with and without MCP using an impedance-based scratch assay. Migration represents a key factor in the metastatic cascade and a proxy for metastatic potential. Impedance-based assays offer a sensitive, label-free, and nondestructive method to continuously monitor cancer cells in real-time, allowing assessment of both the kinetics and degree of migration after scratch. Cells were plated on a PDL-coated CytoView-Z 96-well plate (n = 28 per cell line), and their impedance was continuously monitored on the Maestro Z impedance platform. After 72 hours, cells were switched to low-serum media to transition the cells into a reduced proliferative state. Impedance was monitored for another 24 hours, and then a scratch was performed in 20 wells per cell type and migration into the gap was assessed in real-time on the Maestro Z for 80 hours. Migration extent was corroborated with microscopy. Both MCF-7 and HCC1806 initially attached and spread, resulting in a steady increase in impedance. HCC1806 reached confluency by 60 hours, while MCF-7 continued to proliferate for a higher maximum impedance. After scratch, both cell types showed a large decrease in impedance compared to unscratched controls. Impedance of MCF-7 scratched wells remained low over time, suggesting the cells did not migrate into the scratch. Conversely, HCC1806 cells showed an initial decrease in impedance, but a subsequent increase over time, returning to near unscratched values after 48 hours, suggesting migration into the gap. Treatment with MCP slowed migration for both cell types, indicating antimetastatic properties. Both responded more to in-house MCP compared to PectaSol-C. The impedance-based scratch assay revealed differences in migration, a key factor in metastatic potential, across breast cancer lines and was sensitive to small differences in antimetastatic MCP potencies. HCC1806 showed more extensive migration following scratch compared to MCF-7, mirroring the greater metastatic potential of TNBC. In addition, MCP slowed and reduced migration, confirming its antimetastatic potential which may vary depending on the modification applied. Support for this work was provided by It's the Journey/Georgia Center for Oncology Research & Education Breast Cancer Research Award.
Citation Format: Longjing Zhu, Stacie A. Chvatal, Heather B. Hayes, Daniel C. Millard, Cheryl T. Gomillion. Modified citrus pectin slows migration of triple negative breast cancer cells in an impedance-based scratch assay [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4918.