Abstract B086: Cellular context-dependent regulation of cancer cell invasion and migration in pancreatic tumor spheroids co-cultured with pancreatic stellate cells

Abstract

Purpose Invasion of cancer cells is the initial step of metastatic progression. Elucidation of the cellular and molecular mechanisms of invasion may provide novel strategies to modulate metastasis and survival. The plasticity of cancer cells and surrounding stroma induces cell migration of which three types have been reported: collective, mesenchymal, or amoeboid type of movement. Here we investigated differential invasion phenotype and underlying mechanisms using two pancreatic cancer cells, BxPC-3 (wild-type KRAS, epithelial type) and PANC-1 (mutated KRAS, intermediate type) under 3D culture conditions. Methods Multicellular tumor spheroids (TS) were cultured in 3D collagen gel matrix either as mono-culture or under pancreatic stellate cell (PSC) co-culture condition using micro-channel chips. TS formation, cell migration within and outside of collagen gel, ECM remodeling, and expression of proteins involved in epithelial-mesenchymal transition (EMT) as well as degradation of matrix proteins were evaluated using immunofluorescence confocal microscopy, real-time live cell imaging and subsequent image analysis. Results BxPC-3 cells formed highly compact TS with strong expression of E-cadherin compared to PANC-1 cells. BxPC-3 cells showed collective migration under mono-culture condition and showed 50% phenotypic conversion to amoeboid single cell migration under PSC co-culture condition. Lamellipodia formation with actin spikes were observed in both types of cell migration in BxPC-3 cells. PANC-1 cells showed mostly mesenchymal invasion with single cells migrating out of TS using invadopodia. PANC-1 cells showed significantly higher level of vimentin and TGF-β as compared to BxPC-3 cells. Extensive ECM remodeling with collagen densification and fiber alignment was shown with BxPC-3 cells, compared to that of PANC-1 cells, under both mono- and PSC co-culture conditions. Similar levels of collagen degradation and expression of MT1-MMP, integrin β1 and pFAK between the two cell lines strongly suggest additional mechanisms of mechanical deformation of ECM facilitated by traction force of BxPC-3 cells, which warrants further studies. When cancer cells and PSCs migrated out of collagen matrix channels to encounter, fibronectin-mediated cell-cell interaction leading to co-migration was observed in both cell lines. Conclusions We demonstrated cellular context-dependent regulation of cancer cell invasion and its association with cancer cell-ECM and cancer cell-PSC interaction in pancreatic TS co-cultured with PSC. Our 3D TS-PSC co-culture recapitulates the differential modes of cancer cell invasion; hence, it may serve as an efficient and in vivo mimic model to study cellular and molecular mechanisms of invasion. Citation Format: Seul-ki Kim, Min-Suk Oh, Hyo-Jeong Kuh. Cellular context-dependent regulation of cancer cell invasion and migration in pancreatic tumor spheroids co-cultured with pancreatic stellate cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B086. doi:10.1158/1535-7163.TARG-19-B086