Abstract

Targeting microenvironmental factors that foster migratory cell phenotypes is a promising strategy for halting tumor migration. However, lack of mechanistic understanding of the process impedes pharmaceutical drug development. Using a novel 3D microtumor model with tight control over tumor size, we recapitulated tumor size-induced hypoxic microenvironment and emergence of migratory phenotypes in epithelial T47D breast microtumors as well as those of patient-derived primary metastatic breast cancer cells, mesothelioma cells and lung cancer xenograft cells (PDX). The microtumor models from various patient-derived tumor cells and PDX cells revealed upregulation of tumor secretome, matrix metalloproteinase-9 (MMP9), fibronectin (FN), and soluble E-cadherin (sE-CAD) consistent with the clinically reported elevated levels of FN and MMP9 in the patient breast tumors compared to healthy mammary gland. We further showed that the tumor secretome induces migratory phenotype in non-hypoxic, non-migratory small microtumors. Subsequent mathematical model analysis identified a two-stage microtumor progression and migration mechanism, i.e., hypoxia induces migratory phenotype in the early initialization stage, which then becomes self-sustained through positive feedback loop established among the secretome. Both computational and experimental studies showed that inhibition of tumor secretome effectively halts microtumor migration despite tumor heterogeneity, while inhibition of the hypoxia is effective only within a time window and is compromised by tumor-to-tumor variation of the growth dynamics, supporting our notion that hypoxia initiates migratory phenotypes but does not sustain it. In summary, we show that targeting temporal dynamics of evolving microenvironments during tumor progression can halt and bypass major hurdle of tumor heterogeneity.