Loss of HMGA1 and PA2G4 inhibited proliferation, migration, and adhesion potential of MM cells in vitro. (A) MM.1S cells infected with nontargeting control sgRNAs or HMGA1, PA2G4, and MYC targeting sgRNAs were cultured with and without BMSCs from relapsed/refractory MM patients for 48 hours. Proliferation rates were normalized to control sgRNA–infected cells cultured without BMSCs, and cells with loss of HMGA1, PA2G4, or MYC exhibited significantly reduced proliferation. (B) BMSCs were seeded 1 day ahead in the lower chamber of 96-transwell plate. MM.1S cells transduced as described in panel A were seeded in the upper chamber for 4 hours. The percentage of cells that migrated to the lower chamber was normalized to control cells without BMSCs, and cells with loss of HMGA1, PA2G4, or MYC exhibited significantly reduced migration toward BMSCs. (C) MM.1S cells transduced as described in panel A were prelabeled with Calcein-AM and cocultured with preseeded BMSCs for 2 hours. The percentage of cells that adhered to BMSCs was normalized to control sgRNA–infected cells, and loss of HMGA1, PA2G4, or MYC compromised the adhesion rates significantly. Two experiments from 2 independent infections were performed, and 1 representative result is shown. Error bars indicate standard deviation. *P < .05, **P < .01, ***P < .001.