Stemness and chemoresistance in epithelial ovarian carcinoma cells under shear stress

Abstract

One of greatest challenges to the successful treatment of cancer is drug resistance. An exciting approach is the eradication of cancer stem cells (CSCs). However, little is known about key signals regulating the formation and expansion of CSCs. Moreover, lack of a reliable predictive preclinical model has been a major obstacle to discover new cancer drugs and predict their clinical activity. Here, in ovarian cancer, a highly chemoresistant tumor that is rapidly fatal, we provide the first evidence demonstrating the causal involvement of mechanical stimulus in the CSC phenotype using a customizable microfluidic platform and three-dimensional spheroids, which most closely mimic tumor behavior. We found that ovarian cancer cells significantly acquired the expression of epithelial-to-mesenchymal transition and CSC markers and a remarkable chemoresistance to clinically relevant doses of frontline chemotherapeutic drugs cisplatin and paclitaxel when grown under fluid shear stress, which corroborates with the physiological attainable levels in the malignant ascites, but not under static condition. Furthermore, we uncovered a new link of microRNA-199a-3p, phosphatidylinositol 3-kinase/Akt, and multidrug transporter activation in shear stress-induced CSC enrichment. Our findings shed new light on the significance of hydrodynamics in cancer progression, emphasizing the need of a flow-informed framework in the development of therapeutics.

Review: Mechanotransduction in ovarian cancer: Shearing into the unknown

“…Concurrently, EMT was enhanced through the upregulation of gene and protein expression of Snail, Slug, and N-cadherin, and downregulation of E-cadherin. 29 Apart from substantiating the work of Rizvi et al, they found that the shear stress stimulated cells were chemoresistant to cisplatin and paclitaxel treatment, as previously hypothesized. 31 The CSC phenotypes and chemoresistance were attributed to the PI3K/Akt signaling pathway, where LY294002, a specific inhibitor to PI3K, abated the previously observed enhanced CSC marker expression.…”

“…31 The flow-induced EMT was predicted to influence the chemoresistance of cells and the effectiveness of targeted inhibitors. These predictions were sequentially validated by Ip et al 29 Expanding upon the previous findings of Rizvi et al, Ip et al sought to identify the role of CSC in ovarian cancer chemoresistance. SKOV3, a p53 mutant clear cell adenocarcinoma cell line, was first grown into spheroids before being placed under extremely low shear conditions (0.02 and 0.002 dyn/cm 2 ) in a microfluidic shear device 29 [ Fig.…”

“…16 The presence of ascitic fluid has been shown to aid in metastasis 28 and chemoresistance. 29,30 It also mechanically stimulates the cancer with hydrostatic compression and shear forces. The ascitic fluid flow is triggered by gravity, changes in diaphragmatic pressure from breathing, surrounding organ movement aiding digestion, and bodily movements like walking.…”

“…It has been predicted that shear stress values within ascites are low, with relatively little to no support in either experimental or mathematical modeling. 29,31,45 Computer simulated models are required to improve our understanding of the physiological stresses that occur within the peritoneal cavity. A diseased patient's musculoskeletal/organ movements cause a change in the shape of the peritoneal cavity which in turn causes fluid movement within the ascites.…”

“…29,[49][50][51] However, only a few published studies have investigated shear stress stimulation of ovarian cancer cells in 2D or 3D culture models. To answer the question of how fluid flow induced wall shear stress affects the cytoskeleton of ovarian cancer and regulates its penetration and spread to the peritoneum, Avraham-Chakim et al fabricated a custom-made 2D shear stress device 45 [shown in Fig.…”