BRD4通过SHH信号通路诱导甲状腺癌细胞增殖、侵袭与迁移

BRD4 induces proliferation, invasion and migration of thyroid cancer cells via SHH signaling pathway

背景与目的:甲状腺癌是目前发病率最高的内分泌系统恶性肿瘤之一,目前的综合治疗手段虽然效果较好,但是部分患者在随后的治疗中会出现继发性摄碘率下降,131I治疗效果差,从而导致复发及远处转移。近年来的研究发现,溴样结构域蛋白4(double bromodomain-containing protein 4,BRD4)可促进多种恶性肿瘤的进展,因此本研究旨在探究BRD4在甲状腺乳头状癌(papillary thyroid cancer,PTC)细胞中的作用,寻找治疗甲状腺癌的特异性靶点。方法:应用实时荧光定量聚合酶链反应(real-time fluorescent quantitative polymerase chain reaction,RTFQ-PCR)检测PTC组织和癌周组织中BRD4的表达差异,应用si BRD4干扰基因转染PTC细胞株TPC-1,应用蛋白[质]印迹法(Western blot)检验沉默效果,通过MTT实验、平板克隆实验、Transwell小室侵袭与迁移实验检验沉默BRD4前后PTC细胞株TPC-1活力、增殖、迁移及侵袭等生物学行为的变化。进一步应用Western blot及RTFQ-PCR检测钠碘转运体(sodium iodide symporter,NIS)基因及蛋白的表达变化,以及SHH信号通路下游基因SHH、GLI1表达变化情况。结果:BRD4在PTC组织中表达明显增高(P<0.05);在体外实验中BRD4沉默后PTC细胞株TPC-1的细胞活力、增殖、迁移与侵袭能力下降。此外,BRD4沉默后NIS基因及蛋白表达增高,SHH信号通路下游基因SHH、GLI1表达降低(P<0.05)。结论:BRD4通过上调SHH信号通路相关基因促进PTC细胞的侵袭与迁移,沉默BRD4可以促进NIS的表达,BRD4有望成为治疗甲状腺癌的新靶点。

Background and purpose： Thyroid cancer is the endocrine malignant tumor with the highest incidence. Although comprehensive treatment has gotten considerable effect, some patients have low iodine uptake and poor 131I therapeutic effect in the subsequent treatment which causes recurrence and distant metastasis. Recent studies have found that double bromodomain-containing protein 4 （BRD4） plays a key role in promoting the progression of some malignant tumors. Therefore, we aimed to investigate the effect of BRD4 in papillary thyroid cancer （PTC）, and search for the specific target of thyroid cancer. Methods： Real-time fluorescence quantitative polymerase chain reaction （RTFQ-PCR） was used to examine the BRD4 expression in PTC tissue and para-cancerous tissue. PTC cell line TPC-1 was transfected with the siBRD4. And then the silence efficiency was examined by Western blot. The effects of BRD4 on cell viability, proliferation, migration and invasion were examined by MTT assay, colony formation assay and transwell assay. Besides, Western blot and RTFQ-PCR were used to examine the expression of sodium iodide symporter （NIS） and the downstream gene SHH and GLI1 of SHH signaling pathway. Results： BRD4 was overexpressed in PTC tissue （P〈0.05）. In vitro experiment showed that the viability, proliferation, invasion and migration of BRD4-silencing cells were decreased. Besides, the mRNA and protein expression levels of NIS were up-regulated while the downstream gene of SHH signaling pathway SHH and GLI1 were down-regulated （P〈0.05）. Conclusion： BRD4 would promote the invasion and migration of papillary thyroid cancer cells via up-regulating the genes of SHH signaling pathway. Silencing BRD4 can promote the expression of NIS. BRD4 may be a new target for the treatment of thyroid cancer.