Project Summary
The majority of breast cancer related deaths occur as a result of metastasis. Once the cancer cells
metastasize, the 5-year relative survival rate for breast cancer patients drastically drops. During
metastasis, a complex series of events is initiated by changes in the extracellular matrix (ECM)
composition and architecture in distant tissues, where the metastatic cancer cells take root and form
secondary tumors. These distinct changes in the premetastatic niche (PMN) facilitate tumor cell
colonization, phenotypic heterogeneity of the cell population, and contribute to drug resistance frequently
observed in metastatic tumors. Using an engineered model of the PMN, we have demonstrated that
extracellular vesicles (EVs) facilitate dynamic changes in premetastatic tissues, and that blocking key
events during PMN formation disrupts the metastatic process. Our preliminary studies indicate that ECM
proteins transglutaminase 2 (TG2) and fibronectin (FN) play a significant role in establishing the PMN
through an EV-dependent mechanism. However, fundamental gaps remain in identifying critical events
within the niche that facilitate metastatic colonization of tumor cells, cellular plasticity, and drug
resistance. The overall goal of this proposal is to identify how the dynamic changes within the metastatic
niche make the distant tissues hospitable to metastatic cancer cells. Aim 1 will use our novel model of
the PMN to identify how specific changes in the PMN facilitate colonization by disseminating cells. Aim
2 is focused on isolating specific effects of ECM dynamics and cellular constituents within the PMN that
impact phenotypic heterogeneity and immunogenicity, giving rise to growth permissive and grow
restrictive environments. Aim 3 will identify mechanisms by which key matrix components within the niche
protect metastatic tumor cells from therapeutic agents. Our cross-disciplinary team encompasses
expertise in biomedical engineering, metastasis, imaging, and EV biology. The proposed studies will
establish novel mechanisms by which the PMN facilitates breast cancer metastasis, an essential step
towards successful treatments to disrupt the metastatic process.