Department of Pathology, Zhongshan Hospital, Xiamen University, Xiamen, Fujian, China.
Department of Otolaryngology-Head and Neck Surgery, Zhongshan Hospital, Xiamen University, Xiamen, Fujian, China.
Int J Med Sci. 2021 Jan 1;18(1):42-52. doi: 10.7150/ijms.49792. eCollection 2021.
Special AT-rich sequence binding protein 1 (SATB1) is a chromatin organizer and transcriptional regulator which regulate numerous cellular processes through effects on multiple gene expression. SATB1 is associated with drug resistance in several cancers. Whether SATB1 involves radiation resistance in nasopharyngeal carcinoma (NPC) and underlying mechanism of SATB1 to participate in chemoradiotherapy resistance in NPC have not been elaborated. Chemoradioresistant NPC cell lines 5-8F/DDP (cisplatin) and 5-8F/R (radiation) were developed from 5-8F cell line. The expressions of SATB1, MMP-9 and EMT markers (Vimentin and E-cadherin) in these cell lines were examined by reverse transcription-quantitative (RT-q) PCR and western blot (WB) analysis. Cell viabilities of 5-8F/DDP treated with various concentrations of DDP and 5-8F/R irradiated with various doses of X-ray at the indicated time were investigated by MTT test. SATB1 was silenced in 5-8F/DDP and 5-8F/R cells by short hairpin RNA, and then the expressions of SATB1, MMP-9, Vimentin and E-cadherin were evaluated by RT-qPCR and WB analysis; the abilities of cell proliferation and invasion were assessed using MTT and transwell assays, respectively. Drug and radiation resistance assays were performed after SATB1 knockdown and cell viability was detected by MTT method. SATB1, MMP-9 and Vimentin were markedly upregulated in 5-8F/DDP and 5-8F/R cells compared with 5-8F cell, whereas E-cadherin was obviously downregulated. 5-8F/DDP and 5-8F/R cells displayed drug and radiation resistance to DDP or X-irradiation, respectively, while DDP or X-irradiation inhibited 5-8F cell viability in a time- and dose-dependent manner. Subsequently, knockdown of SATB1 resulted in decreased MMP-9 and Vimentin expression and increased E-cadherin expression in 5-8F/DDP and 5-8F/R. Furthermore, silencing of SATB1 suppressed proliferative and invasive abilities of 5-8F/DDP and 5-8F/R cells. Additionally, SATB1 knockdown reduced drug resistance of 5-8F/DDP cell to DDP and decreased radiation resistance of 5-8F/R cell to X-ray. These results suggest that high expression of SATB1 plays an important role in the malignant behavior of NPC and leads to X-radiation and drug resistance in NPC through promoting EMT process and enhancing MMP-9 expression. SATB1 may be a promising therapeutic target for aggressive and chemoradiation resistant NPC.
SATB1 是一种富含特殊 AT 的序列结合蛋白 1，它是一种染色质组织因子和转录调控因子，可通过对多种基因表达的影响来调节多种细胞过程。SATB1 与多种癌症的耐药性有关。然而，SATB1 是否参与鼻咽癌（NPC）的放射抵抗以及 SATB1 参与 NPC 化放疗抵抗的潜在机制尚未阐明。
从 5-8F 细胞系中开发出了耐化疗的 NPC 细胞系 5-8F/DDP（顺铂）和 5-8F/R（辐射）。通过逆转录定量（RT-q）PCR 和 Western blot（WB）分析检测这些细胞系中 SATB1、MMP-9 和 EMT 标志物（波形蛋白和 E-钙粘蛋白）的表达。用 MTT 试验检测在不同浓度顺铂处理的 5-8F/DDP 细胞和不同剂量 X 射线照射的 5-8F/R 细胞的细胞活力。用短发夹 RNA 沉默 5-8F/DDP 和 5-8F/R 细胞中的 SATB1，然后通过 RT-qPCR 和 WB 分析评估 SATB1、MMP-9、波形蛋白和 E-钙粘蛋白的表达；分别用 MTT 和 Transwell 测定法评估细胞增殖和侵袭能力。在 SATB1 敲低后进行药物和放射抵抗测定，并通过 MTT 法检测细胞活力。
与 5-8F 细胞相比，SATB1、MMP-9 和波形蛋白在 5-8F/DDP 和 5-8F/R 细胞中明显上调，而 E-钙粘蛋白明显下调。5-8F/DDP 和 5-8F/R 细胞对顺铂或 X 射线具有耐药性，而顺铂或 X 射线呈时间和剂量依赖性抑制 5-8F 细胞活力。随后，SATB1 的敲低导致 5-8F/DDP 和 5-8F/R 中 MMP-9 和波形蛋白的表达降低，E-钙粘蛋白的表达增加。此外，SATB1 的敲低抑制了 5-8F/DDP 和 5-8F/R 细胞的增殖和侵袭能力。此外，SATB1 敲低降低了 5-8F/DDP 细胞对顺铂的耐药性，并降低了 5-8F/R 细胞对 X 射线的辐射抗性。
这些结果表明，SATB1 的高表达在 NPC 的恶性行为中起着重要作用，并通过促进 EMT 过程和增强 MMP-9 表达导致 NPC 的 X 射线和药物耐药性。SATB1 可能是治疗侵袭性和化放疗耐药性 NPC 的有前途的治疗靶点。
