# Protocol to study metastatic dormancy using 4T07-mCherry breast cancer cells and an algorithm-based quantification of disseminated cancer cells

## TL;DR

This paper provides a detailed protocol to study dormant breast cancer cells in mice using a specific cell line and an algorithm to track cancer spread.

## Contribution

The novel contribution is an algorithm-based method to quantify disseminated cancer cells in the lungs during metastatic dormancy.

## Key findings

- A protocol for orthotopic injection of 4T07-mCherry breast cancer cells into mice is described.
- An algorithm-based approach enables quantification of disseminated cancer cells in lung tissue.
- The protocol supports studying the induction and awakening of metastatic dormancy.

## Abstract

Dormant disseminated cancer cells are responsible for late relapses of breast cancer. Here, we present a protocol to orthotopically inject 4T07-mCherry breast cancer cells into mice and describe how to resect the primary tumor. We detail steps for collecting and processing the lungs to detect and quantify cancer cells using an algorithm-based approach. This protocol allows studying the induction, maintenance, and awakening from metastatic dormancy.

For complete details on the use and execution of this protocol, please refer to Pereira et al.1

•Steps for injecting breast cancer cells in the mammary fat pad without surgery•Instructions to surgically resect a breast primary tumor•Guidance on collecting and processing lungs for immunofluorescence analysis•Steps to quantify disseminated cancer cells in the lungs with an algorithm-based approach

Steps for injecting breast cancer cells in the mammary fat pad without surgery

Instructions to surgically resect a breast primary tumor

Guidance on collecting and processing lungs for immunofluorescence analysis

Steps to quantify disseminated cancer cells in the lungs with an algorithm-based approach

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Dormant disseminated cancer cells are responsible for late relapses of breast cancer. Here, we present a protocol to orthotopically inject 4T07-mCherry breast cancer cells into mice and describe how to resect the primary tumor. We detail steps for collecting and processing the lungs to detect and quantify cancer cells using an algorithm-based approach. This protocol allows studying the induction, maintenance, and awakening from metastatic dormancy.