Metastasis-relevant cellular constrictions as determinants for resistance to cell death and cancer aggressiveness

How mechanical stress might influence the resistance of cancer cells to cell death is currently unknown. To address this, we mimicked the mechanical constrictions that cancer cells might encounter when invading through rich tumoral stroma or undergoing intra- and extravasation. We found that extreme constrictional migration (ECM) but not compression increases the resistance of breast cancer cells to anoikis, a variant of apoptosis triggered by loss of cell adhesions. We also found that Inhibitory of Apoptosis Proteins (IAPs) are responsible for ECM-triggered resistance to anoikis. Together with enhanced cell motility and resistance to natural killer-mediated immune-surveillance, we show that anoikis resistant ECM mechanically-challenged cancer cells have a marked advantage to form lung metastatic lesions. Taken together, our study connects the constrictional mechanical stress typically characterizing the metastatic colonization with the resistance to cell death, while therapeutically targeting the IAPs by SMAC mimetics could counteract anoikis resistance in breast cancer cells. A Transwell assay was performed to distinguish cells that are subject to constriction (also refered to as “down” or “Bottom” cells throughout the text), from those that do not migrate (also refered to as “up” or “Top” control cells). RNA sequencing from control and mechanically-challenged MDA-MB-231 cells was done by the CRCL Cancer Genomics core facility. Sequencing was performed using the NextSeq500 Illumina sequencer in 75 bp paired-end.