ETS1-SPIN1-PI3K/Akt网络调控乳腺癌耐药的分子机制研究

Breast cancer resistance is an important cause of poor prognosis in patients. SPIN1 is a novel histone code “reader”, which is related to the occurrence and development of tumors. Previously we found that it was highly expressed in breast cancer drug-resistant tissues and could up-regulate PI3K/Akt pathway to promote breast cancer drug resistance. However, the upstream and downstream regulation mechanism of SPIN1 in breast cancer needs further investigation. Preliminary experiment suggests that the transcription factor ETS1 could bind to the promoter region of SPIN1 to promote its expression, while SPIN1 could bind to the promoter region of the PI3K/Akt pathway regulator EGFR and promote its transcription. We speculate that ETS1, which is up-regulated in breast cancer, could promote SPIN1 transcription, and SPIN1 could also promote EGFR transcription, thereby activating PI3K/Akt pathway and promoting breast cancer drug resistance. This study intends to further explore the expression and clinical significance of SPIN1 and ETS1 in breast cancer, investigate the effects on breast cancer drug resistance in vitro and in vivo, and verify the ETS1/SPIN1/EGFR regulation axis. The construction of the ETS1-SPIN1-EGFR-PI3K/Akt regulatory network is expected to provide new potential targets for reversing breast cancer drug resistance.

乳腺癌耐药是患者预后不良的重要原因。SPIN1是一种新型组蛋白“阅读器”，与肿瘤的发生发展相关，本课题组发现其在乳腺癌耐药组织中高表达，可以上调PI3K/Akt通路进而促进乳腺癌耐药。然而目前乳腺癌中SPIN1上下游调控机制有待进一步研究。前期预实验提示转录因子ETS1可结合到SPIN1的启动子区，促进其表达；而SPIN1可结合到PI3K/Akt通路调节因子EGFR的启动子区，促进其转录。本课题组推测乳腺癌中表达上调的ETS1可促进SPIN1转录，SPIN1亦可促进EGFR转录，进而激活PI3K/Akt通路，促进乳腺癌耐药。本研究拟进一步探究SPIN1及ETS1在乳腺癌中的表达及临床意义，研究其在体外、体内对乳腺癌耐药的影响，验证ETS1对SPIN1及SPIN1对EGFR的调控作用，从而构建ETS1-SPIN1-EGFR-PI3K/Akt调控网络，有望为逆转乳腺癌耐药提供新的潜在靶点。

乳腺癌是女性常见的恶性肿瘤之一，也是女性癌症死亡的主要原因。化疗耐药常导致乳腺癌患者预后不良。Spindlin1（SPIN1）是SPIN/SSTY家族的成员，其在卵巢癌和脂肪肉瘤中高表达，与肿瘤的发生发展相关。本研究组前期研究发现miRNA-489可抑制乳腺癌细胞的耐药性、增殖和迁移浸润能力，SPIN1是miRNA-489的直接靶基因。本研究组推测，SPIN1也可能在乳腺癌耐药中发挥重要作用。本研究使用免疫组化的方法检测了SPIN1在乳腺癌组织中的表达情况，分析了其与乳腺癌化疗反应、淋巴结转移等临床病理参数的关系。通过体外功能学实验研究了SPIN1对乳腺癌细胞耐药的影响，并使用基因表达芯片筛选、荧光素酶实验、western blot等手段初步探究了其可能的上下游分子机制。本研究通过生物信息学分析发现SPIN1 mRNA在化疗效果差的乳腺癌患者中表达较高。乳腺癌穿刺的石蜡标本中，SPIN1在乳腺癌耐药组织及伴有淋巴结转移组织中表达上调；新鲜乳腺癌组织中，SPIN1在伴有淋巴结转移组织中表达上调；在乳腺癌耐药细胞与高转移性细胞中表达上调。生物信息学分析提示SPIN1高表达与乳腺癌患者预后不良相关。细胞功能学实验显示SPIN1可增强乳腺癌细胞对阿霉素的化疗耐药性。机制上，SPIN1上调PI3K/Akt通路中PIK3CA、AKT、CREB1及BCL2表达。转录因子SP1激活SPIN1转录，上调SPIN1表达。综上，本研究发现SPIN1在乳腺癌耐药及转移性组织及细胞中表达上调，SPIN1高表达与乳腺癌患者预后不良相关。SPIN1正向调控PI3K/Akt通路，促进乳腺癌细胞的耐药性。转录因子SP1结合到SPIN1的启动子区，激活SPIN1转录，促进SPIN1的表达。本研究首次对SPIN1在乳腺癌耐药中的作用及机制进行深入探讨，有望为SPIN1成为乳腺癌诊疗靶点奠定基础。