Cancer metastases are responsible for most deaths from the disease. However, most current cancer therapies are anti-proliferative, rather than anti-metastatic. Challenges to the clinical realization of anti-metastatic therapies include dose-limiting toxicity to non-cancer cells, effective targeting, effective timing of administration given that metastasis is an early cancer process, and effectiveness in the face of adaptive invasion strategies by cancer cells. An ideal platform to test anti-metastatic therapeutic candidates would mimic the tumor microenvironment, and accurately assess cancer cell motile phenotypes as well as pro-invasion microstructural signatures in the extracellular matrix. This proposal aims to 1) develop a dual-modality quantitative phase and polarized light microscopy system capable of 2) evaluating the effects of inhibitors of matrix invasion and microenvironmental factors on the spread of cancer cells in a tissue-like in vitro environment. Quantitative optical indices from the proposed system accurately assess cell phenotype and microstructural signatures of invasion, by evaluating cell phase and matrix birefringence signals. These imaging modalities also deliver low optical power to the sample, allowing for long-term, serial microscopy without phototoxic effects on cancer cell movement. Finally, an innovative but simple culture set-up creates collagen networks with alignment and pre-stress similar to the tumor microenvironment. Steps to achieve these aims include addition of polarizing optics to an existing digital holographic microscope, signal calibration, channel co-registration, and initial time-lapse imaging of an in vitro 3D model of cancer invasion. Optical indices of invasion will be evaluated in a scaled-up study. After installing a second camera and full polarization state generator and analyzer on the existing digital holographic microscope, phase and birefringence signals will be evaluated and co-registered using a polystyrene microsphere standard (n=1.59) set in solid mounting media (n=1.52). Phase and polarized light parameters will be calibrated by computing phase maps of standard beads of fixed diameter, and optical retardance of a zero-order waveplate. The invasion of the breast cancer cell line MDA-MB-231 will be evaluated from serial time-lapse imaging over 24 hours, in the presence and absence of 30 nM chondramide, an actin-stabilizing anti-metastatic therapeutic candidate. The effects of pre-stress and extracellular matrix alignment will also be evaluated. The health-relatedness of this proposal lies in development of a quantitative phase and polarized light microscope that computes parameter maps for invading cancer cells and their microenvironmental surroundings. The proposed microscope reduces phototoxicity and provides quantitative metrics for accurate assessment of the mechanisms and aggressiveness of cancer cell invasion, thus enabling testing of anti- metastatic drug candidates.
The complex microstructure of the tumor microenvironment and flexible invasion strategies of cancer cells are challenges to the realization of anti-metastatic therapies. A dual-modality microscope that provides non- invasive, quantitative, and extended time-lapse imaging of cells and extracellular matrix microstructure would accurately evaluate characteristics of invasion from 3D in vitro models. Knowledge gained from such an instrument would include quantitative optical indices of invasion, potentially translatable as imaging biomarkers in slide sections of biopsies, as well as a way to evaluate potential anti-metastatic therapies.
