Iskander Aurrekoetxea-Rodriguez, So Young Lee, Miriam Rábano, Isabel Gris-Cárdenas, Virginia Gamboa-Aldecoa, Irantzu Gorroño, Isabella Ramella-Gal, Connor Parry, Robert M Kypta, Beñat Artetxe, Juan M Gutierrez-Zorrilla, Maria dM Vivanco
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引用次数: 0
Abstract
Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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.
期刊介绍:
Cell Communication and Signaling (CCS) is a peer-reviewed, open-access scientific journal that focuses on cellular signaling pathways in both normal and pathological conditions. It publishes original research, reviews, and commentaries, welcoming studies that utilize molecular, morphological, biochemical, structural, and cell biology approaches. CCS also encourages interdisciplinary work and innovative models, including in silico, in vitro, and in vivo approaches, to facilitate investigations of cell signaling pathways, networks, and behavior.
Starting from January 2019, CCS is proud to announce its affiliation with the International Cell Death Society. The journal now encourages submissions covering all aspects of cell death, including apoptotic and non-apoptotic mechanisms, cell death in model systems, autophagy, clearance of dying cells, and the immunological and pathological consequences of dying cells in the tissue microenvironment.