Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong.
Division of Hematology, Mayo Clinic, Rochester, MN, USA.
Br J Haematol. 2020 Jul;190(2):249-261. doi: 10.1111/bjh.16517. Epub 2020 Feb 20.
miR-1258 is localised to the first intron of ZNF385B at chromosome 2q31.3. miR-1258 promoter methylation was studied in 147 samples including 10 normal buffy coat, eight normal bone marrow plasma cells, 16 human myeloma cell lines (HMCLs), 20 MGUS, 63 diagnostic myeloma, and 30 relapsed myeloma samples by methylation-specific PCR. In myeloma lines, miR-1258 methylation, verified by pyrosequencing, was detected in 62·5% HMCLs but not normal controls, and expression of miR-1258 correlated with that of ZNF385B. 5-Aza-2'-deoxycytidine resulted in promoter demethylation and ZNF385B/miR-1258 re-expression. Luciferase assay confirmed programmed cell death ligand-1 (PDL1) as a direct target of miR-1258. Over-expression of miR-1258 in completely methylated myeloma cells led to reduced cellular proliferation and enhanced apoptosis, hence a tumour suppressor role, in addition to repression of PDL1. In primary samples, miR-1258 methylation, with lower expression of miR-1258, was detected in 49·2% diagnostic myeloma, imparting an inferior PFS (P = 0·034) in addition to 50·0% relapsed myeloma but not MGUS. Therefore, miR-1258 is a tumour suppressor miRNA co-regulated with its host gene, and frequently hypermethylated in active myeloma instead of MGUS, hence acquired during myeloma progression. Methylation-mediated miR-1258 silencing led to overexpression of PDL1 and inferior PFS, implicating miR-1258 in the modulation of myeloma-specific cytotoxicity.
miR-1258 位于染色体 2q31.3 上的 ZNF385B 的第一个内含子中。通过甲基化特异性 PCR 研究了 147 个样本中的 miR-1258 启动子甲基化情况，包括 10 个正常血涂片、8 个正常骨髓浆细胞、16 个人骨髓瘤细胞系（HMCL）、20 个 MGUS、63 个诊断性骨髓瘤和 30 个复发性骨髓瘤样本。在骨髓瘤系中，通过焦磷酸测序验证了 miR-1258 的甲基化，在 62.5%的 HMCL 中检测到，但在正常对照中未检测到，并且 miR-1258 的表达与 ZNF385B 的表达相关。5-Aza-2'-脱氧胞苷导致启动子去甲基化和 ZNF385B/miR-1258 重新表达。荧光素酶测定证实程序性细胞死亡配体 1（PDL1）是 miR-1258 的直接靶标。在完全甲基化的骨髓瘤细胞中过表达 miR-1258 会导致细胞增殖减少和凋亡增加，从而发挥肿瘤抑制作用，此外还会抑制 PDL1。在原发性样本中，在 49.2%的诊断性骨髓瘤中检测到 miR-1258 甲基化和 miR-1258 表达降低，这会导致无进展生存期（PFS）较差（P=0.034），此外在 50.0%的复发性骨髓瘤中但不在 MGUS 中。因此，miR-1258 是一种与宿主基因共同调控的肿瘤抑制 miRNA，并且在活动期骨髓瘤中经常过度甲基化而不是在 MGUS 中，因此是在骨髓瘤进展过程中获得的。甲基化介导的 miR-1258 沉默导致 PDL1 过表达和 PFS 较差，表明 miR-1258 参与了骨髓瘤特异性细胞毒性的调节。
