Brain and Breast Cancer Cells with PTEN Loss of Function Demonstrate Enhanced Durotaxis and RHOB Dependent Amoeboid Migration Using 3D Printed Scaffolds and Aligned Microfiber Tracts

Abstract

Background: Glioblastoma multiforme (GBM) and triple-negative breast cancer (TNBC) with PTEN mutations often lead to brain dissemination with very poor patient outcomes. GBM uses axons and vessels as migratory cues to disseminate, however it is not known, if TNBC shares the same behavior. There is a need to understand brain tumor cell spreading and if GBM and TNBC have similar migration properties involving the signaling pathway RHOB-ROCK-PTEN. We tested for durotaxis, adherence and migration of GBM and TNBC using live-cell imaging and performed molecular analyses on three-dimensional (3D) structures.Methods: Aligned 3D printed scaffolds and microfibers were designed to mimic brain axon tracts and vessels for migration. GBM and TNBC cell lines, each with opposing PTEN genotypes, were analysed with RHO, ROCK and PTEN inhibitors and rescuing PTEN function using live-cell imaging. RNA-sequencing and qPCR of tumor cells in 3D with microfibers were performed, while SEM, confocal microscopy and cell tracking addressed cell morphology. Results: GBM and TNBC with homozygote PTEN loss of function and RHOB high expression were amoeboid shaped and demonstrated enhanced durotaxis, adhesion and migration on 3D microfibers, in contrast to PTEN wildtype GBM and TNBC showing elongated cells and low RHOB. RNA-sequencing exhibited that RHOB was significantly the highest expressed gene in GBM PTEN loss of function cells. Pathway inhibitors and PTEN rescue of function verified an essential role of RHOB-ROCK-PTEN signaling for durotaxis, adhesion, migration, cell morphology and plasticity using 3D printed microfibers. Conclusions: This study validates a significant role of a PTEN genotype for cellular properties including durotaxis, adhesion and migration. GBM and TNBC cells with PTEN loss of function have a greater affinity for stiffer brain structures promoting metastasis. We propose the significance of PTEN and RHOB in cellular oncology not only for primary tumors, but also for metastasizing tumors, where RHOB inhibitors could play an essential role for improved therapy.