TRIM21 downregulation is associated with a high relapse rate in human MM. (A) qRT-PCR and (B) western blot analysis of TRIM21 expression in 9 MM cell lines (MM1R, MM.1S, JJN3, ARP-1, U266, U266-Bort, OPM2, RPMI8226, and CAG) and peripheral blood mononuclear cells (PBMCs) from 1 healthy donor. (C) The histochemistry score for TRIM21 was evaluated using BM biopsy samples when the patients were newly diagnosed and relapsed after treatment with a bort-based regimen (median H-score from 9.222222 to 6.388889). Pt.1 to Pt.18 represent 18 independent patients. (D) Immunohistochemical analysis of TRIM21 expression in 3 representative BM biopsies (Pt.1-Pt.3). The top panel shows TRIM21 expression in newly diagnosed patients, and the bottom panel shows TRIM21 expression after the relapse of the same patients after treatment with a bort-based regimen. Scale bars; 100 μm. (E) Kaplan-Meier survival analysis in the indicated myeloma data sets. Patients were divided into 2 groups based on TRIM21 expression levels (red curve: high TRIM21 expression; blue curve: low TRIM21 expression). (F) TRIM21 expression according to bort response (CR, n = 14; MR, n = 23; NC, n = 60; PD, n = 66; PR, n = 76). (G) TRIM21 expression in the CD138+ plasma cells of patients with monoclonal gammopathy of undetermined significance (MGUS, n = 7), MM (n = 39), and plasma cell leukemia (PCL, n = 6). The y-axis indicates the median log value of TRIM21 retrieved from the original data set. (H) MM patients with 1q amplified chromosomal abnormalities have low TRIM21 expression according to qRT-PCR detection. (∗P < .05; ∗∗P < .01; ∗∗∗P < .001).