Cancer Technologies
Eric N. Horst (he/him/his)
Graduate Student Researcher
University of Michigan
Ann Arbor, Michigan, United States
Liam Cotter (he/him/his)
Undergraduate Researcher
University of Michigan, United States
Mia Bonini
Graduate Student Researcher
University of Michigan, United States
Zoe Jackson
Undergraduate Researcher
University of Michigan, United States
Zachary Fischer
Undergraduate Researcher
University of Michigan, United States
Linh Tran
Undergraduate Researcher
University of Michigan, United States
David Nordsletten
Associate Professor
University of Michigan, United States
Caymen Novak
Assistant Professor
University of Michigan, United States
Geeta Mehta, Ph.D.
Primary Investigator
University of Michigan
Ann Arbor, Michigan, United States
Sub-Track: Tumor Microenvironment
With a five-year survival rate of fifty percent, ovarian cancer is predicted to cause more than 13,000 deaths yearly within the United States alone1. The ovarian tumor microenvironment (TME) facilitates this high mortality by accelerating disease progression and metastasis, rendering early detection ineffective2. Accumulation of fluid within the peritoneal cavity, or ascites, typically follows high grade serous ovarian cancer (HGSC) progression. Ascites volume correlates with reduced survival, as volumes greater than 1.8 L are associated with a 29-month decrease of median survival in HGSC3. Ascitic currents promote transcoelomic metastasis and exert fluid shear stress (FSS) on tumors, to induce the epithelial-to-mesenchymal transition (EMT)4,5. Moreover, ascites contains pro-tumoral soluble factors and tumor-associated macrophages (TAM) that promote metastasis and immunosuppression6. While the relationship between FSS and tumor progression is well established, the exact magnitude of FSS, the mechanotransduction pathways responsible for enhancing metastasis, and their impact on the innate immune microenvironment remain unclear. In order to solve this complex problem for a dynamic TME, we estimated FSS in the ascites using human radiological data and utilized a biologically-relevant tumor-mimetic interpenetrating hydrogel and a bioreactor capable of generating a wide range of shear stresses, to probe the molecular mechanisms of mechanotransduction on HGSC.
Stimulation of HGSC with physiologically relevant FSS increased metastatic potential via induction of EMT, activation of p38 MAPK, and downregulation of MUC15, a transmembrane glycoprotein of the glycocalyx associated with migration and invasion8. Computational modeling of ascitic currents based on diaphragmatic movement predicted FSS greater than 5 dynes/cm2 on the ovarian surface. However, when the fluid flow is augmented by musculoskeletal movement, the predicted maximum FSS was 11 dynes/cm2, which is orders of magnitude larger than previously predicted9. FSS stimulation at 11 dynes/cm2 increased the cell motility of HGSC-specific cell lines OVCAR3 and OVSAHO and promoted a more mesenchymal phenotype as evidenced by increased invasion and migration, increased actin cytoskeletal dynamics, and downregulation of E-cadherin (Fig. 1A-C). FSS stimulation contributed to increased cell motility by inducing phosphorylation of p38 MAPK which in turn leads to the phosphorylation of heat shock protein-27 (HSP27), an effector of F-actin trafficking (Fig. 1B,D)10. Consistent with the p38 MAPK activation, FSS increased nuclear localization of NF-κB, a transcription factor associated with immunosuppression and invasion (Fig. 1E)11. IPA based on RNA-seq indicated that FSS increased the secretion of cytokines such as IL-6 and TGF-β, which recruit TAM and promote an immunosuppressive TME, as confirmed from the conditioned medium from FSS-stimulated HGSC, and 3D hetero-spheroid model of HGSC-TAM12. Furthermore, FSS downregulated MUC15, which was sufficient to increase the migration of OVCAR3 and OVCAR4 cells (Fig. 1C,F). To determine if MUC15 was necessary or sufficient for the FSS induced changes, the MUC15 transduced cell lines were treated with FSS and evaluated for EMT markers and altered migratory potential. Additionally, G-protein coupled receptors (GPCRs) were identified by IPA to be upstream of p38 MAPK activation, positioning GPCRs as potential mechanosensors for FSS. Overall, these findings solidify p38 MAPK and MUC15 as critical effectors of FSS-mediated HGSC progression and provide new avenues for targeted therapies.
This work is supported primarily by the American Cancer Society Research Scholar Award RSG-19-003-01-CCE (G.M.), NSF EFRI DChem (Award number 2029139). Research reported in this publication was supported by the National Cancer Institute under award number R37CA282790 and P30CA046592. We are grateful to undergraduate students (Alec R. Sunshine, Linh Tran, Zoe Jackson, Zachary Fisher) who participated in this research work.