Immobilization rapidly selects for chemoresistant ovarian cancer cells with enhanced ability to enter dormancy

Abstract

Around 20–30% of ovarian cancer patients exhibit chemoresistance, but there are currently no methods to predict whether a patient will respond to chemotherapy. Here, we discovered that chemoresistant ovarian cancer cells exhibit enhanced survival in a quiescent state upon experiencing the stress of physical confinement. When immobilized in stiff silica gels, most ovarian cancer cells die within days, but surviving cells exhibit hallmarks of single‐cell dormancy. Upon extraction from gels, the cells resume proliferation but demonstrate enhanced viability upon reimmobilization, indicating that initial immobilization selects for cells with a higher propensity to enter dormancy. RNA‐seq analysis of the extracted cells shows they have signaling responses similar to cells surviving cisplatin treatment, and in comparison to chemoresistant patient cohorts, they share differentially expressed genes that are associated with platinum‐resistance pathways. Furthermore, these extracted cells demonstrate greater resistance to cisplatin and paclitaxel, despite being proliferative. In contrast, serum starvation and hypoxia could not effectively select for chemoresistant cells upon removal of the environmental stress. These findings demonstrate that ovarian cancer chemoresistance and the ability to enter dormancy are linked, and immobilization rapidly distinguishes chemoresistant cells. This platform could be suitable for mechanistic studies, drug development, or as a clinical diagnostic tool.

Induction of dormancy by confinement: An agarose‐silica biomaterial for isolating and analyzing dormant cancer cells

“…A subsequent study we conducted with dormancy-capable ovarian cancer cell lines (SKOV-3 and OVCAR-3) further showed that the state of dormancy enhanced chemoresistance. 50 Studies conducted by others on MDA-MB-231 cells encapsulated in photo-crosslinked RGDS laden PEG gels support our findings that high matrix stiffness, independent of adhesion, is sufficient to induce single cell dormancy. 44 Using a collagen-PEG gel, Reynolds et al also confirm that immobilization in stiff gels inhibits proliferative activity of MDA-MB-231s even in the presence of strong ECM protein binding.…”

“…Note that serum starvation induces dormancy via p38 phosphorylation and ERK dephosphorylation, and therefore is considered a positive control 55. The p38:ERK activity ratio after 3 days of immobilization in MSPEG was 2.80 ± 0.57 times that of the TCPS control, a value similar to that measured in cells grown in serum-free media (3.02 ± 1.69) (Figure6a,b).We also used qRT-PCR to explore the expression changes in proliferation intermediate genes, which are indicative of dormancy in ovarian cancer cells 50. CDK-cyclin complexes such as cyclindependent kinase 2 (CDK2), cyclin D1 (CCND1), and cyclin E1…”

“…We have previously shown that inhibition of proliferation through encapsulation in a silica gel selects for dormancy-capable cells. 38,39,50 As compared to immobilization in silica gels, 39 we have observed a significant increase in the survival of MCF-7 and MDA-MB-231 cells when they were immobilized in agarose-silica gels. Cells can attach to silica gels (Figure S6), while agarose fully inhibits attachment.…”

“…Full immobilization is needed to induce the selection pressure to isolate the dormant cell populations. 39,50 24-hr live cell imaging was conducted to confirm that MCF-7 (Figure 3a), and MDA-MB-231 cells (Figure 3e) were fully immobilized by MSPEG encapsulation. Oscillatory rheology revealed that the agarose-silica composite gel reached a storage modulus of G 0~2 kPa with a loss modulus of G 00~1 00 Pa within 15 min of gelation, rapidly reaching the levels previously shown to immobilize cells 39 (Figure S2).…”

The Influence of Ligand Density and Degradability on Hydrogel Induced Breast Cancer Dormancy and Reactivation

“…For instance, braintropic cells are known to overexpress ST6GALNAC5 [36] which is a sialyltransferase that transfers sialic acid to oligosaccharides that can alter both cell-cell and cell-ECM interactions. [70,71] ST6GALNAC5 mediates infiltration into the brain by enhancing adhesion to, and interactions with, brain endothelial cells allowing penetration through the blood brain barrier. [36] In the same manner that ST6GALNAC5 mediates cell-ECM interactions in the brain, ST6GALNAC5 may also alter ECM interactions in the hydrogels implemented here, leading to the observed existence as cell clusters rather than solitary cells observed in gel 2.…”