Chaiyawat Parunya, Sirikaew Nutnicha, Budprom Piyaporn, Klangjorhor Jeerawan, Phanphaisarn Areerak, Teeyakasem Pimpisa, Settakorn Jongkolnee, Pruksakorn Dumnoensun
Musculoskeletal Science and Translational Research (MSTR) Center, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
Omics Center for Health Sciences (OCHS), Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
J Bone Oncol. 2020 Sep 22;25:100321. doi: 10.1016/j.jbo.2020.100321. eCollection 2020 Dec.
Abnormality in the DNA methylation process is one of the hallmarks of cancer. Emerging evidence strongly supports the idea that defects in DNA methyl transferases (DNMTs) are involved in tumor development and progression. This alteration has major effects at the transcription level of various cancer-associated genes.
Expression profiles of DNMT1 were investigated in fresh frozen tissues, patient-derived cells, and formalin-fixed paraffin-embedded tissues using immunoblotting and immunohistochemistry analysis. We also examined an anti-tumor effect of single DNA-hypomethylating agent (decitabine) and a combination of decitabine and chemotherapy in osteosarcoma cell lines.
The results showed an overexpression of DNMT1 in most cases compared to normal cells and tissue samples. DNMT1 was also expressed at the same levels in paired primary cells derived from biopsy and post-chemotherapy tissues. Expression patterns of DNMT1 were examined in 77 osteosarcoma patients of whom 82% had positive DNMT1 with an IRS score > 0. Most of the cases expressed low to moderate levels of DNMT1 (IRS range 1-8, median = 2.0). Furthermore, we found that a combination of decitabine and chemotherapy had a synergistic effect in most of the tested osteosarcoma cells at a low dose therapeutic range of decitabine.
Our study revealed DNMT1 expression patterns that indicated potential roles of DNMT1 in osteosarcoma transformation and progression. This finding also suggests the efficacy of a combination therapy of decitabine with chemotherapy for osteosarcoma treatment.
DNA甲基化过程异常是癌症的标志之一。新出现的证据有力地支持了DNA甲基转移酶（DNMTs）缺陷参与肿瘤发生和发展的观点。这种改变在各种癌症相关基因的转录水平上有重大影响。
使用免疫印迹和免疫组织化学分析，在新鲜冷冻组织、患者来源的细胞以及福尔马林固定石蜡包埋组织中研究DNMT1的表达谱。我们还检测了单一DNA低甲基化剂（地西他滨）以及地西他滨与化疗联合使用对骨肉瘤细胞系的抗肿瘤作用。
结果显示，与正常细胞和组织样本相比，大多数情况下DNMT1呈过表达。DNMT1在来自活检组织和化疗后组织的配对原代细胞中也以相同水平表达。在77例骨肉瘤患者中检测了DNMT1的表达模式，其中82%的患者DNMT1呈阳性，免疫反应评分（IRS）>0。大多数病例表达低至中等水平的DNMT1（IRS范围为1 - 8，中位数 = 2.0）。此外，我们发现，在地西他滨的低剂量治疗范围内，地西他滨与化疗联合使用在大多数测试的骨肉瘤细胞中具有协同作用。
我们的研究揭示了DNMT1的表达模式，表明DNMT1在骨肉瘤转化和进展中具有潜在作用。这一发现还表明地西他滨与化疗联合治疗骨肉瘤具有疗效。
