癌症干细胞 (CSC) 含量增加和 SOX2 过度表达是激素依赖性乳腺癌产生治疗耐药性的常见特征，这仍然是一个重要的临床挑战。 SOX2 具有作为治疗耐药性生物标志物和治疗靶点的潜力，但靶向转录因子也具有挑战性。在这里，我们研究了不同的多金属氧酸盐（POM）衍生物对他莫昔芬耐药乳腺癌细胞中SOX2转录因子的潜在抑制作用。合成了各种POM衍生物，并通过红外光谱、粉末X射线衍射图和核磁共振波谱进行了表征。雌激素受体 (ER) 阳性乳腺癌细胞及其对激素疗法他莫昔芬产生耐药性的对应细胞，用 POM 进行处理，并通过凝胶阻滞和染色质免疫沉淀来评估其后果，以确定 SOX2 与 DNA 的结合。使用显微镜、克隆形成、transwell、伤口愈合测定、流式细胞术和体内鸡绒毛尿囊膜（CAM）模型监测和量化对增殖、迁移、侵袭和致瘤性的影响。使用 CRISPR-Cas9 基因组编辑产生慢病毒稳定基因沉默和基因敲除，以验证所选 POM 的抑制效果。通过乳腺球形成测定、ALDEFLUOR 活性和 CD44/CD24 染色对癌症干细胞亚群进行定量。使用流式细胞术和蛋白质印迹法来测量活性氧(ROS)和细胞凋亡。POMs阻断内源性SOX2的体外结合活性。 [P2W18O62]6- (PW) Wells-Dawson 型阴离子在抑制他莫昔芬耐药的各种细胞系模型中的增殖方面最为有效。 10 µM PW 还降低了癌细胞迁移和侵袭以及 SNAI2 表达水平。用 PW 处理他莫昔芬耐药细胞，通过以 SOX2 依赖性方式减少 CSC 含量来损害肿瘤形成，从而导致体内干细胞耗竭。从机制上讲，PW 诱导活性氧 (ROS) 的形成并抑制 Bcl-2，导致他莫昔芬耐药细胞死亡。 PW 处理的他莫昔芬耐药细胞显示出对他莫昔芬的敏感性恢复。总而言之，这些观察结果强调了 PW 作为 SOX2 抑制剂的潜在用途以及靶向 SOX2 治疗他莫昔芬耐药乳腺癌的治疗相关性。© 2024。作者。

Increased cancer stem cell (CSC) content and SOX2 overexpression are common features in the development of resistance to therapy in hormone-dependent breast cancer, which remains an important clinical challenge. SOX2 has potential as biomarker of resistance to treatment and as therapeutic target, but targeting transcription factors is also challenging. Here, we examine the potential inhibitory effect of different polyoxometalate (POM) derivatives on SOX2 transcription factor in tamoxifen-resistant breast cancer cells.Various POM derivatives were synthesised and characterised by infrared spectra, powder X-ray diffraction pattern and nuclear magnetic resonance spectroscopy. Estrogen receptor (ER) positive breast cancer cells, and their counterparts, which have developed resistance to the hormone therapy tamoxifen, were treated with POMs and their consequences assessed by gel retardation and chromatin immunoprecipitation to determine SOX2 binding to DNA. Effects on proliferation, migration, invasion and tumorigenicity were monitored and quantified using microscopy, clone formation, transwell, wound healing assays, flow cytometry and in vivo chick chorioallantoic membrane (CAM) models. Generation of lentiviral stable gene silencing and gene knock-out using CRISPR-Cas9 genome editing were applied to validate the inhibitory effects of the selected POM. Cancer stem cell subpopulations were quantified by mammosphere formation assays, ALDEFLUOR activity and CD44/CD24 stainings. Flow cytometry and western blotting were used to measure reactive oxygen species (ROS) and apoptosis.POMs blocked in vitro binding activity of endogenous SOX2. [P2W18O62]6- (PW) Wells-Dawson-type anion was the most effective at inhibiting proliferation in various cell line models of tamoxifen resistance. 10 µM PW also reduced cancer cell migration and invasion, as well as SNAI2 expression levels. Treatment of tamoxifen-resistant cells with PW impaired tumour formation by reducing CSC content, in a SOX2-dependent manner, which led to stem cell depletion in vivo. Mechanistically, PW induced formation of reactive oxygen species (ROS) and inhibited Bcl-2, leading to the death of tamoxifen-resistant cells. PW-treated tamoxifen-resistant cells showed restored sensitivity to tamoxifen.Together, these observations highlight the potential use of PW as a SOX2 inhibitor and the therapeutic relevance of targeting SOX2 to treat tamoxifen-resistant breast cancer.© 2024. The Author(s).