Fig 2: HP1? and its acetylation modification are associated with BTZ resistance in MM cells.a Schematic illustration of the manipulation of SILAC assay in the BR and WT MM.1 S cells. b Shown were 176 differential expressed proteins including 48 downregulated and 128 upregulated proteins (cutoff, 1.5 folds), furthermore, 167 proteins whose acetylation level were changed involving 50 downregulation and 117 upregulation (cutoff, 1.5 folds) in the BR MM.1 S cells compared to the WT cells detected by SILAC assay. c Venn diagram showed the most prominent change of protein-HP1? in proteomics and acetylated omics of WT and BR MM cells. d Analysis of acetylated peptides identified specific acetylation motifs associated with lysine acetylation. e Relative b2+ intensity for K5 acetylation in WT and BR MM cells by mass spectrum (mean ± s.d.; n = 1). f Western blots showed the protein and acetylation levels of HP1? in BR and WT MM cells. g Co-immunoprecipitation (Co-IP) assay showed the protein and acetylation levels of HP1? in BR and WT MM cells with HP1?-flag stably overexpression. Input, 2% lysate. IP, M2-flag antibody. h Correlation of CBX3 (HP1?) expression with overall survival (OS) in 586 patients after receiving BTZ-based treatment regimens from the coMMpass cohort. i Expression of CBX3 in patients acquired with complete response (CR) (n = 114) and partial response (PR) (n = 125) in coMMpass cohort, and (j) in MM patients with responses (R, n = 84) and without response (non-R, n = 125) to BTZ-based regimens in the cohort GSE2658. 200037 and 201097, two probes in gene array. k Representative immunohistochemical staining of HP1? protein in specimen from two patients acquired complete response (CR) or disease progression (DP) after treatment. l Alteration of IC50 to BTZ treatment in the NT Ctrl and HP1? KD cells (n = 3). m Quantification of the percentage of apoptotic cells in the Vector with HP1? OE cells and NT Ctrl with HP1? KD cells induced by 10 nM BTZ for 24 h by flow cytometry assay and analyzes the difference between two groups for n = 4 independent experiments (mean ± s.d.). P values were determined by Pearson’s coefficient and log-rank test (h) and Student’s t test (i, j, m). Source data are provided as a Source data file.