Seventy-five percent of patients with epithelial ovarian cancer present with advanced-stage disease that is extensively disseminated intraperitoneally and prognosticates the poorest outcomes. Primarily metastatic within the abdominal cavity, ovarian carcinomas initially spread to adjacent organs by direct extension and then disseminate via the transcoelomic route to distant sites. Natural fluidic streams of malignant ascites triggered by physiological factors, including gravity and negative subdiaphragmatic pressure, carry metastatic cells throughout the peritoneum. We investigated the role of fluidic forces as modulators of metastatic cancer biology in a customizable microfluidic platform using 3D ovarian cancer nodules. Changes in the morphological, genetic, and protein profiles of biomarkers associated with aggressive disease were evaluated in the 3D cultures grown under controlled and continuous laminar flow. A modulation of biomarker expression and tumor morphology consistent with increased epithelial–mesenchymal transition, a critical step in metastatic progression and an indicator of aggressive disease, is observed because of hydrodynamic forces. The increase in epithelial–mesenchymal transition is driven in part by a posttranslational up-regulation of epidermal growth factor receptor (EGFR) expression and activation, which is associated with the worst prognosis in ovarian cancer. A flow-induced, transcriptionally regulated decrease in E-cadherin protein expression and a simultaneous increase in vimentin is observed, indicating increased metastatic potential. These findings demonstrate that fluidic streams induce a motile and aggressive tumor phenotype. The microfluidic platform developed here potentially provides a flow-informed framework complementary to conventional mechanism-based therapeutic strategies, with broad applicability to other lethal malignancies.

Ascites refers to the abnormal accumulation of fluid in the peritoneum resulting from an underlying pathology, such as metastatic cancer. Among all cancers, advanced-stage epithelial ovarian cancer is most frequently associated with the production of malignant ascites and is the leading cause of death from gynecologic malignancies. Despite decades of evidence showing that the accumulation of peritoneal fluid portends the poorest outcomes for cancer patients, the role of malignant ascites in promoting metastasis and therapy resistance remains poorly understood. This review summarizes the current understanding of malignant ascites, with a focus on ovarian cancer. The first section provides an overview of heterogeneity in ovarian cancer and the pathophysiology of malignant ascites. Next, analytical methods used to characterize the cellular and acellular components of malignant ascites, as well the role of these components in modulating cell biology, are discussed. The review then provides a perspective on the pressures and forces that tumors are subjected to in the presence of malignant ascites and the impact of physical stress on therapy resistance. Treatment options for malignant ascites, including surgical, pharmacological and photochemical interventions are then discussed to highlight challenges and opportunities at the interface of drug discovery, device development and physical sciences in oncology.

Metastatic ovarian cancer (OvCa) frequently recurs due to chemoresistance, highlighting the need for nonoverlapping combination therapies that mechanistically synergize to eradicate residual disease. Photodynamic therapy (PDT), a photochemistry-based cytotoxic modality, sensitizes ovarian tumors to platinum agents and biologics and has shown clinical promise against ovarian carcinomatosis. We introduce a three-dimensional (3D) model representing adherent ovarian micrometastases and high-throughput quantitative imaging methods to rapidly screen the order-dependent effects of combining benzoporphyrin-derivative (BPD) monoacid A–based PDT with low-dose carboplatin. 3D ovarian micronodules grown on Matrigel were subjected to BPD-PDT either before or after carboplatin treatment. We developed custom fluorescence image analysis routines to quantify residual tumor volume and viability. Carboplatin alone did not eradicate ovarian micrometastases at a dose of 400 mg/m², leaving surviving cores that were nonsensitive or impermeable to chemotherapy. BPD-PDT (1.25 μmol/L·J/cm²) created punctate cytotoxic regions within tumors and disrupted micronodular structure. Treatment with BPD-PDT prior to low-dose carboplatin (40 mg/m²) produced a significant synergistic reduction [P < 0.0001, analysis of covariance (ANCOVA)] in residual tumor volume [0.26; 95% confidence interval (95% CI), 0.19–0.36] compared with PDT alone (0.76; 95% CI, 0.63–0.92) or carboplatin alone (0.95; 95% CI, 0.83–1.09), relative to controls. This synergism was not observed with the reverse treatment order. Here, we demonstrate for the first time the use of a 3D model for micrometastatic OvCa as a rapid and quantitative reporter to optimize sequence and dosing regimens of clinically relevant combination strategies. This approach combining biological modeling with high-content imaging provides a platform to rapidly screen therapeutic strategies for a broad array of metastatic tumors. Cancer Res; 70(22); 9319–28. ©2010 AACR.