Invasion of the blood system is a significant step towards the
metastatic spread of cancer cells, which is a significant threat to
patients with cancer.
A research team at Georgetown Lombardi Comprehensive Cancer Center
has described the steps, in both written and video format, that allow
cancer investigators to track, in real time, cancer cell invasion and
metastasis in transparent zebrafish embryos. Using these fish models,
researchers can find answers to cancer questions in one to three days
instead of months for the typical mouse model.
‘Cancer researchers have provided a hands-on, detailed description of a unique model system to study cancer cell vascular invasion.’
Because of this rapidity and the ability to image cancer movement in
blood, investigators say the use of zebrafish embryos represent a
significant advance in the understanding of cancer biology and
experimental drug testing, and may, one day, lead to tumor assessment
and treatment evaluation in patients.
The method and its implications, published in the Journal of Visualized Experiments
(JoVE), "will be of a lot of interest to cancer researchers because it
provides a hands-on, detailed description of a unique model system to
study cancer cell vascular invasion," says the study's co-senior
investigator, Anton Wellstein, a Georgetown professor of
oncology & pharmacology, and deputy director of the Georgetown
Center for Cell Reprogramming.
Wellstein said, "This method uses human cancer cells in
zebrafish and can reveal distinct invasive properties of cancer cells,
help identify genes that drive vascular invasion as well as allow to
test drugs that inhibit it."
Zebrafish - a tropical freshwater minnow commonly used in aquariums - has been widely used as a model organism in scientific research, but
has only recently been adapted for use in studying cancer, says
co-author Eric Berens, a PhD student in Wellstein's laboratory.
"It's being increasingly used in oncology research, but the
technique, which has a lot of moving parts, hadn't been written up. We
felt listing and filming the steps would encourage more scientists to
use this wonderful tool to advance their investigations," he says.
Wellstein, Berens, and co-author Ghada Sharif, also a member of
the Wellstein lab, worked with Eric Glasgow, PhD, who directs
Georgetown's zebrafish laboratory, to articulate the method's steps.
(Glasgow is co-senior investigator on the JoVE study.)
The video shows how fluorescent human cancer cells can be injected
into developing embryos, and how 24-96 hours later, the ability of the
cells to invade the blood and spread can be seen using fluorescence
microscopy. The team tested seven different breast cancer cell lines to
determine which invaded the blood system, and how aggressively.
"We can use these beautiful fluorescent images to see how invasive
various human cancers are and whether they respond to drug treatment,"
Using the zebrafish model to uncover drivers of tumor aggression,
the team has published two major studies in Oncogene. Wellstein was the
corresponding author for both studies.
One study, led by Sharif and published in 2015, demonstrated that
the ability of cancer cells to invade is influenced by the density at
which those cells are grown. Another 2016 article, led by Berens, used a
screening approach to identify unstudied genes that control cancer cell
invasion and metastasis. Researchers found that keratin-associated
protein 5-5 (Krtap5-5) is important for cancer cell invasion out of
"One could envision using this model system in the future to test
how aggressive an individual person's cancer is, and what treatments
might work best against it," Berens says.