BCMA overexpression enhances MM tumor growth in vivo via upregulation of multiple MM-related genes and immunosuppressive molecules. (A) Mice (n = 6) were injected subcutaneous with equal numbers of R-BCMA (solid line) or R-empty (control vector, dotted line) cells, and tumor development was monitored. *P < .002. Tumors were removed at day 40. (B) Immunohistochemistry for tumor sections with similar volume from additional mice were used for CD31/MVD assessment. Original magnification, ×200. (C) Fold increase in 19 mRNA levels in R-BCMA vs R-empty cells was determined by real-time qRT-PCR. GAPDH and 18S were used as internal controls. (D) Programmed death ligand 1 (PD-L1) increase in R-BCMA vs R-empty cells was further confirmed with immunofluorescence staining (left; PD-L1, pink and DAPI, blue) and immunoblotting (right). (E) RNA of R-BCMA– and R-empty–derived tumors was further assayed for IL-10 pathway-associated genes using TaqMan array human IL10 pathway. Transcripts were normalized by geomean of 4 internal controls, and fold increases in R-BCMA vs R-empty cells are shown.