DataSheet_1_SIPL1, Regulated by MAZ, Promotes Tumor Progression and Predicts Poor Survival in Human Triple-Negative Breast Cancer.doc

BackgroundTriple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer owing to a lack of effective targeted therapy and acquired chemoresistance. Here, we explored the function and mechanism of shank-interacting protein-like 1 (SIPL1) in TNBC progression.
MethodsSIPL1 expression was examined in human TNBC tissues and cell lines by quantitative reverse transcription PCR, western blot, and immunohistochemistry. SIPL1 overexpression and silenced cell lines were established in BT-549 and MDA-MB-231 cells. The biological functions of SIPL1 in TNBC were studied in vitro using the CCK-8 assay, CellTiter-Glo Luminescent Cell Viability assay, caspase-3/8/9 assay, wound healing assay, and transwell assay and in vivo using a nude mouse model. The potential mechanisms underlying the effects of SIPL1 on TNBC progression were explored using bioinformatics analysis, luciferase reporter assays, and chromatin immunoprecipitation followed by qPCR.
ResultsSIPL1 expression was higher in human TNBC tissues and cell lines than in adjacent normal tissues and a breast epithelial cell line (MCF10A). High expression of SIPL1 was positively correlated with poor overall and disease-free survival in patients with TNBC. SIPL1 overexpression elevated and SIPL1 silencing repressed the malignant phenotypes of TNBC cells in vitro. SIPL1 overexpression promoted xenograft tumor growth in vivo. Myc-associated zinc-finger protein (MAZ) transcriptionally activated SIPL1. Finally, we found that SIPL1 promoted TNBC malignant phenotypes via activation of the AKT/NF-κB signaling pathways.
ConclusionsThese results indicate that the MAZ/SIPL1/AKT/NF-κB axis plays a crucial role in promoting the malignant phenotypes of TNBC cells.

背景 三阴性乳腺癌（triple-negative breast cancer, TNBC）是一类侵袭性乳腺癌亚型，由于缺乏有效靶向治疗手段且易产生获得性化疗耐药性，临床诊疗面临较大挑战。本研究探讨了Shank相互作用蛋白样1（shank-interacting protein-like 1, SIPL1）在三阴性乳腺癌进展中的功能与作用机制。
方法 采用定量逆转录聚合酶链反应、蛋白质印迹法及免疫组织化学染色，检测人三阴性乳腺癌组织及细胞系中SIPL1的表达水平。在BT-549与MDA-MB-231细胞中分别构建SIPL1过表达及敲低细胞系。通过CCK-8法、CellTiter-Glo荧光素酶细胞活力检测法、半胱天冬酶-3/8/9活性检测法、划痕愈合实验及Transwell实验，体外探究SIPL1对三阴性乳腺癌细胞生物学功能的影响；同时利用裸鼠模型开展体内功能验证实验。通过生物信息学分析、荧光素酶报告基因实验及染色质免疫沉淀联合定量PCR，解析SIPL1调控三阴性乳腺癌进展的潜在分子机制。
结果 相较于癌旁正常组织及乳腺上皮细胞系MCF10A，SIPL1在人三阴性乳腺癌组织与细胞系中的表达水平显著升高。SIPL1高表达与三阴性乳腺癌患者较差的总生存期及无病生存期呈正相关。过表达SIPL1可增强三阴性乳腺癌细胞的恶性表型，而敲低SIPL1则会抑制该恶性表型。体内实验结果显示，SIPL1过表达可促进裸鼠异种移植瘤的生长。MYC相关锌指蛋白（Myc-associated zinc-finger protein, MAZ）可转录激活SIPL1的表达。最后研究发现，SIPL1通过激活AKT/NF-κB信号通路，促进三阴性乳腺癌的恶性表型。
结论 本研究结果表明，MAZ/SIPL1/AKT/NF-κB信号轴在促进三阴性乳腺癌细胞恶性表型的过程中发挥关键调控作用。