The role of clonal communication and heterogeneity in breast cancer

Ana Martín-PardillosEmail author View ORCID ID profile,
Ángeles Valls Chiva†,
Gemma Bande Vargas†,
Pablo Hurtado Blanco,
Roberto Piñeiro Cid,
Pedro J. Guijarro,
Stefan Hümmer,
Eva Bejar Serrano,
Aitor Rodriguez-Casanova,
Ángel Diaz-Lagares,
Josep Castellvi,
Samuel Miravet-Verde,
Luis Serrano,
María Lluch-Senar,
Víctor Sebastian,
Ana Bribian,
Laura López-Mascaraque,
Rafael López-López and
Santiago Ramón y CajalEmail author

†Contributed equally

BMC Cancer201919:666

https://doi.org/10.1186/s12885-019-5883-y

Received: 28 May 2019
Accepted: 26 June 2019
Published: 5 July 2019

Open Peer Review reports

Abstract

Background

Cancer is a rapidly evolving, multifactorial disease that accumulates numerous genetic and epigenetic alterations. This results in molecular and phenotypic heterogeneity within the tumor, the complexity of which is further amplified through specific interactions between cancer cells. We aimed to dissect the molecular mechanisms underlying the cooperation between different clones.

Methods

We produced clonal cell lines derived from the MDA-MB-231 breast cancer cell line, using the UbC-StarTrack system, which allowed tracking of multiple clones by color: GFP C3, mKO E10 and Sapphire D7. Characterization of these clones was performed by growth rate, cell metabolic activity, wound healing, invasion assays and genetic and epigenetic arrays. Tumorigenicity was tested by orthotopic and intravenous injections. Clonal cooperation was evaluated by medium complementation, co-culture and co-injection assays.

Results

Characterization of these clones in vitro revealed clear genetic and epigenetic differences that affected growth rate, cell metabolic activity, morphology and cytokine expression among cell lines. In vivo, all clonal cell lines were able to form tumors; however, injection of an equal mix of the different clones led to tumors with very few mKO E10 cells. Additionally, the mKO E10 clonal cell line showed a significant inability to form lung metastases. These results confirm that even in stable cell lines heterogeneity is present. In vitro, the complementation of growth medium with medium or exosomes from parental or clonal cell lines increased the growth rate of the other clones. Complementation assays, co-growth and co-injection of mKO E10 and GFP C3 clonal cell lines increased the efficiency of invasion and migration.

Conclusions

These findings support a model where interplay between clones confers aggressiveness, and which may allow identification of the factors involved in cellular communication that could play a role in clonal cooperation and thus represent new targets for preventing tumor progression.