Targeting invasive plasticity by inhibiting mitochondrial adaptations to matrix metalloproteinase loss

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Tumor cell invasion through extracellular matrix (ECM) facilitates localized and distant cancer spread, which is the most lethal aspect of cancer. The ability of cells to switch between distinct invasive modes, termed plasticity or adaptation, when faced with varying physical or chemical challenges underlies the inability to develop anti-invasive therapies. Identifying targetable adaptive responses to halt invasion has been hindered by the lack of experimental models to identify, characterize, and test the loss of key molecules that facilitate plasticity. To address this critical need we have focused on matrix metalloproteinases (MMPs), which have been targeted in extensive clinical trials because of their strong association with cancer and role in degrading ECM. Anti-MMP therapies, however, have been ineffective, likely because of invasive plasticity. To identify and understand how invasive cells adapt to MMP loss, we are using the in vivo model of anchor cell (AC) invasion in C. elegans. We found that the genetic removal of MMPs results in an adaptive invasion response where instead of ECM degradation, the AC increases F-actin polymerization to forcefully penetrate ECM. Using MMP-null animals, we performed the first synergistic invasion screen to pinpoint genes that promote adaptive AC invasion and identified the mitochondrial ATP/ADP translocase, ant-1.1, as the strongest candidate. ANTs have multiple mitochondrial functions (ATP/ADP exchange, mitophagy, mitochondrial dynamics) and the ANT-1.1 protein is highly enriched in AC mitochondria that polarize to the site of ECM invasion. ANT-1.1 knockdown in MMP-null animals prevents adaptive F-actin formation and inhibits AC invasion. The overall objective of this application is to (Aim 1) elucidate how ant-1.1 promotes adaptive invasion after MMP loss in C. elegans, and (Aim 2) determine if the concurrent loss of MMP and ANT activity in a 4-D organotypic brain slice model of glioblastoma (GBM) blocks invasive activity. Our central hypothesis is that understanding how ANT-1.1 functions in mitochondrial for adaptive invasion will facilitate targeting ANTs along with MMPs in a clinically relevant brain slice model of GBM invasion. To understand how ANT-1.1 promotes adaptive invasion, will use genetic analysis, fluorescence reporters, metabolic biosensors, cell-specific metabolic analysis, and quantitative live-cell imaging. We will then use quantitative confocal imaging to directly test the efficacy of combined ANT and MMP therapies on GBM cell invasion. We expect to establish how ANT-1.1 functions within mitochondria to facilitate adaptive invasion (possibly through multiple functions) and to develop combined therapeutic approaches to effectively block GBM invasion. These contributions will be significant as they will reveal how invasive cells adaptively invade in the absence of MMPs and establish a pipeline that can be used to identify and characterize synergistic invasive targets resulting in more effective cancer therapies.