In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 110, No. 22 ( 2013-05-28)
Abstract:
The present study addresses the significant challenge of studying metastatic tumor cell growth under physiologically relevant conditions that restore critical physical and stromal cues in the tumor microenvironment. These findings highlight the important role of dynamic forces, such as flow-based stress, in the fate as well as the molecular and biological features of tumor metastases. The versatile microfluidic platform for 3D tumor growth described here realizes a physiologically relevant model for ovarian cancer metastasis and is a broadly applicable technology enabling the study of a variety of cancers and other pathological conditions. Our approach suggests the need to develop comprehensive treatment strategies that account for the role of physical factors, including flow, to complement conventional mechanism-based drug discovery and combination therapeutic strategies. An important marker, particularly in metastatic ovarian cancer, is the epidermal growth factor receptor (EGFR) ( 4 ). The EGFR regulates proliferation, survival, and growth; high levels of this receptor may signify worse outcomes for ovarian cancer patients ( 4 ). In the present study, a significant flow-induced increase in EGFR protein expression and activation was observed with no change in EGFR gene expression, suggesting a late-stage, posttranslational stress response. E-cadherin is a protein that mediates cell–cell adhesions as part of a complex that includes β-catenin. Loss of E-cadherin is associated with increased metastatic potential and a poor prognosis in ovarian cancer. The presence of flow caused a significant decrease in E-cadherin gene and protein expression ( Fig. P1 C ) and a concomitant significant decrease in β-catenin protein expression. Decreased E-cadherin expression and a concurrent increase in vimentin, a cytoskeletal protein that helps maintain cell and tissue integrity, are hallmarks of epithelial-to-mesenchymal transition (EMT) ( 5 ). Tumors that undergo EMT generally adopt a spindle-like morphology and often are aggressive and resistant to treatment ( 5 ). The data show a significant flow-induced increase in vimentin expression and morphological changes consistent with EMT. There also was a significant decrease in the volumes and viabilities of 3D tumors under flow compared with nonflow cultures, consistent with the decreased proliferation associated with EMT ( 5 ) and indicative of the high attrition rates that cancer cells experience as they colonize distant sites ( 1 ). Ovarian cancer is the leading cause of death from gynecologic tumors and spreads primarily along natural fluidic streams in the abdominal cavity ( Fig. P1 A ) ( 3 ). However, the role of these fluidic streams as physical modulators of heterogeneity in ovarian cancer biology ( 2 ) remains poorly understood. To investigate the effects of physical and stromal cues on the molecular and morphological features of 3D ovarian micronodules, we cultured human ovarian cancer cells in microfluidic channels under sustained flow ( Fig. P1 B ). Tumor morphology, volume, and viability, as well as the gene and protein expression profiles of key molecular pathways, were characterized in the resulting 3D tumors and compared with matched nonflow 3D cultures. The platform reveals flow-induced alterations in a panel of biomarkers and changes in morphological features associated with aggressive and highly metastatic disease ( Fig. P1 C ). Nearly 90% of cancer - related deaths occur in patients whose disease spreads, or metastasizes, to distant sites ( 1 ). A major challenge in understanding and managing cancer metastases is to identify the microenvironmental cues that influence tumor heterogeneity, particularly in disseminated disease ( 1 , 2 ). Tumor dissemination and growth are influenced by a complex array of factors, including the physical stresses that cells encounter as they interact with stromal beds ( Fig. P1 A ) ( 1 ). The goal of this study was to establish the molecular alterations caused by stromal and hydrodynamic influences in the tumor microenvironment that contribute to the diverse biological characteristics of metastatic nodules. We describe the development of a bioengineered microfluidic platform that integrates 3D tumor growth and microfluidics to evaluate the effects of flow on the molecular and morphological changes that occur during the adhesion and growth of tumor metastases ( Fig. P1 B ). These effects are evaluated within the context of ovarian cancer, an example of a lethal malignancy that is well-suited for evaluation in this system.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1216989110
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2013
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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