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Behind the Study: Secretomes from metastatic breast cancer cells induce MSC actions

Researchers describe their paper published in Oncotarget titled, “Secretomes from metastatic breast cancer cells, enriched for a prognostically unfavorable LCN2 axis, induce anti-inflammatory MSC actions and a tumor-supportive premetastatic lung.”

The Behind the Study series transcribes videos of chosen researchers elaborating on their recent papers published in Oncotarget. Visit the Oncotarget YouTube channel for more insights from outstanding authors.

Jonathan Kelber

Hello. I’m Jonathan Kelber, and I’m a associate professor at Cal State Northridge in the Los Angeles area. I’m currently on my sabbatical leave from there as a Fulbright Cancer Research UK Scholar at the University of Manchester. And today my grad student Francesca and I will be telling you a little bit about our work on our recent publication in Oncotarget titled “Secretomes from Metastatic Breast Cancer Cells, Enriched for a Prognostically Unfavorable LCN2 Axis, Induce Anti-Inflammatory MSC Actions and a Tumor-Supportive Premetastatic Lung.”

Generally speaking, my lab is interested in cancer metastasis and how to overcome that as well as how to overcome therapy resistance in both breast and pancreatic cancers.

Francesca Sanchez

Hello, my name is Francesca Sanchez, and I am a master student in the Kelber Laboratory at California State University Northridge. Upon the completion of my master’s program, my hope is to matriculate into a doctoral program where I can continue studying cancer progression.

Jonathan Kelber

So the project that we’ve recently published in Oncotarget had its beginnings back in 2016, actually at the AACR annual conference that was held in New Orleans that year. And it was at the last day in a session entitled “Premetastatic Niches, Exosomes, and Tumor-Secreted Factors” that it occurred to me that most of the work that has been reported in this field has been done or has come to our understanding through the use of immune-deficient animal models. And while that has been for good reasons, since there’s been a number of human tumor cells that have been developed and very well characterized that have specific organotropisms, it also seemed that there was a need for understanding how the premetastatic niche is reprogrammed or primed before tumor cell seeding in the context of models where the immune system is intact.

And so as I returned from this meeting and began talking with my current grad student at the time, Ms. Kayla Meade, another first author on the paper, we began trying to devise some plans for how to approach this issue. And we also discovered that a complication in some of the studies in terms of what we were hoping to do was that there are tumor cells being implanted into these models. Now that might sound a little peculiar, since we’re actually trying to study cancer and we do need to know how these tumor cells are behaving in these models, but what we were interested in is understanding how the secreted factors specifically from these tumor cells act to reprogram or prime these premetastatic niches.

And so having tumor cells implanted or injected into these models, even potentially immune-competent models, pose a complicating factor, and so we wanted to really hone in on the secretomes. And so Kayla began by taking conditioned media from cells, two cell lines, Py230 and Py8119, a metastatic and a non-metastatic line that were developed by Lesley Ellies out of the MMTV poly middle-T mouse, and injecting those to systemically educate these mice. These were C57 black 6 mice. And then to characterize how the lung and brain tissues were changing histologically as well as looking at some immune and mesenchymal stem cell markers.

And, of course, she was interested in how these cells were reprogramming these tissues in comparison to mock conditioned media as a control. And along with an undergraduate in the lab, who’s now moved on to a doctoral program at UC San Diego, Analine Aguayo, she’s also a first author on the paper, they in parallel characterized how these conditioned media samples were affecting either immune cells or mesenchymal stem cells in vitro systems.

And, finally, when Francesca came on board last year, she really rounded out the story by developing a method whereby she took out the educated lung tissue from these mice that had received these conditioned media treatments and dissociated the tissue, reconditioned fresh media, and then evaluated how that tissue that had been primed and then subsequently conditioned media would affect tumor cell proliferation or survival ex vivo.

I’ll let Francesca tell you a little bit now about what she found interesting in the work.

Francesca Sanchez

Well, one of the most tedious aspects of this work was actually establishing a reproducible enzymatic disassociation protocol that would allow and ensure a similar biomass in media that was conditioned from our mouse lungs. This was absolutely worth the time and the effort, since it ended up enabling us to demonstrate that our systemic education of a protocol using conditioned media from our metastatic Py230 cells does, in fact, create a much more promoting environment within the lung tissues of these mice.

Jonathan Kelber

One of the, I think, surprising things that we found in the course of the work was as Kayla was profiling the 18 different factors that had been previously reported to be upregulated in the Py230 versus the Py8119 lines, again, these are soluble factors specifically, only one of them correlated with any prognostic significance, and that was lipocalin 2, or LCN2. And that was surprising, number one, because some of these other 17 factors have been previously reported to play pro-tumorigenic roles in breast cancer. And, number two, it was interesting in that LCN2 has been previously reported to have what seems to be very context-dependent roles in tumor progression, specifically in breast cancer progression. And so certainly an interest in the lab going forward will be to really understand what is that context dependency that allows LCN2 to promote breast cancer progression and metastasis, possibly other pro-tumorigenic functions of that growth factor.

Francesca Sanchez

So I guess coming from there, my group, especially in the Kelber Lab, were incredibly excited to see where this research is going to take us. So currently our work has three different points, or threefold. So, first, we’re interrogating the function of the LCN2 in our both in vitro and in vivo/ex vivo models, using both RNAi and neutralizing methods. Second, we are profiling upstream regulators of LCN2 expression and secretion in breast cancer cells, both mouse and human. And, finally, we are characterizing LCN2 dependent molecular and cellular changes within both the premetastatic lung and brain using RNA-seq methods.

Jonathan Kelber

And I think our long-term goal in this work is really to establish treatment regimens whereby these premetastatic or metastatic niches are rendered unfavorable to host tumor cells, either where they become toxic and kill the tumor cells or they just allow other anti-cancer therapies to come in and actually have a anti-cancer effect on those tumor cells, ultimately improving patient outcomes.

So we’d like to thank Oncotarget very much for the opportunity to publish our work there and opportunity to share this highlight with you here. Bye.

Francesca Sanchez

Bye. Thank you.

Oncotarget: Secretomes from metastatic breast cancer cells induce MSC actions

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