Mechanisms of tumor cell clustering in breast cancer metastasis

肿瘤细胞聚集在乳腺癌转移中的机制

• 批准号: 10744976
• 负责人: Chonghui Cheng
• 金额: $ 46.29万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-28 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10744976
• 关键词: Adherens Junction; Adhesions; Adhesives; Anoikis; Basic Science; Binding; Biological Assay; Blood; Blood Circulation; Blood specimen; Breast Cancer Cell; Breast Cancer Patient; Breast cancer metastasis; Cell Communication; Cell Survival; Cell model; Cell-Cell Adhesion; Cells; ChIP-seq; Characteristics; Chromatin; Chromatin Loop; Clinical Data; Data; Data Analyses; Data Set; Deposition; Development; Disease Progression; Distant; E-Cadherin; Electron Microscopy; Enzymes; Epigenetic Process; Exhibits; Extracellular Matrix; Future; Genetic Transcription; Goals; Hi-C; Histone-Lysine N-Methyltransferase; Homeobox; Hyaluronic Acid; In Vitro; Incidence; Intercellular Junctions; Licensing; Mammary Neoplasms; Mediating; Mediator; Metastatic breast cancer; Morbidity - disease rate; Multiomic Data; Neoplasm Circulating Cells; Neoplasm Metastasis; Organ; Patients; Physiological; Polysaccharides; Primary Neoplasm; Production; Prognosis; Proteins; Regulation; Research; Role; Shapes; Signal Transduction; Stress; Testing; Therapeutic; Transmission Electron Microscopy; Travel; Tumor Promotion; Work; cancer cell; cancer subtypes; clinically relevant; epigenetic regulation; experimental study; gain of function; improved; in vivo; in vivo Model; innovation; insight; loss of function; malignant breast neoplasm; mortality; mouse model; neoplastic cell; novel; novel therapeutic intervention; novel therapeutics; pre-clinical; prevent; promoter; receptor; shear stress; transcription factor; transcriptome sequencing; triple-negative invasive breast carcinoma; tumor; tumor diagnosis

Metastasis is the primary cause of breast cancer-related morbidity and mortality. During metastasis, cells from primary tumors shed into the bloodstream as circulating tumor cells (CTCs). CTCs travel to distant organs to establish secondary tumors. CTCs that form clusters exhibit a drastic increase in metastatic potential compared to single CTCs. While previous studies have described E-cadherin as a key mediator of adhesion in CTC clusters and metastasis, many breast tumors, including tumors of the highly metastatic triple negative breast cancer (TNBC), express little to no E-cadherin. Thus, an alternative, E-cadherin-independent mechanism must exist to mediate clustering between CTCs, thereby promoting metastasis and disease progression. To investigate CTC clustering mechanisms, we developed an in vitro tumor cell clustering assay that incorporates physiological shear force and mimics in vivo conditions. Using this assay, we found that E-cadherin-negative metastatic breast cancer cells can form cellular interactions with characteristics similar to cell adherens junctions. Speculating that extracellular matrix (ECM) components from tumor cells may contribute to CTC clustering, we analyzed ECM components by breast cancer subtypes. We found that hyaluronic acid synthase 2 (HAS2), which is the primary enzyme responsible for hyaluronic acid (HA) production in breast cancer cells, is significantly upregulated in TNBC. We further observed that HA mediates clustering between TNBC tumor cells and confers them with the ability to overcome insults present in the bloodstream, including shear forces. Importantly, we detected HA enrichment at the cell-cell junction of interacting CTCs in TNBC patient blood specimens. Mechanistically, our preliminary results suggest that metastatic TNBC cells upregulate HAS2 expression in a chromatin looping mechanism mediated by PRDM6, a transcriptional regulator and putative histone lysine methyltransferase. Collectively, these preliminary findings lead us to hypothesize that in aggressive TNBC, high levels of HA augment CTC clustering via HA-dependent adhesive interactions between neighboring cells. We further hypothesize that the PRDM6 upregulates HA levels through epigenetic modulation of HAS2 expression, including chromatin looping interactions. We propose to study our hypotheses through two specific aims: 1) determine the role of HA in TNBC tumor cell clustering and metastasis and 2) elucidate the epigenetic regulation of HAS2 that impacts breast tumor cell clustering. To investigate our hypotheses, we will utilize novel in vitro clustering assays and in vivo mouse models along with electron microscopy to reveal the structural characteristics of CTC clusters. In addition, we will utilize integrative multi-omics data analysis to elucidate the co-regulatory network governing HAS2 expression during CTC clustering. Importantly, our results will be extensively validated in blood specimens from metastatic TNBC patients. Consequently, successful completion of our proposed work will not only identify a novel mechanism that mediates strong cell-cell interactions, but also pave the mechanistic groundwork for identifying novel therapeutic options to suppress CTC clustering.

转移是与乳腺癌相关的发病率和死亡率的主要原因。在转移期间，细胞来自 作为循环肿瘤细胞（CTC），原发性肿瘤流入血液中。 CTC前往远处的器官 建立次要肿瘤。形成簇的CTC比较表现出转移潜力的急剧增加 到单个CTC。虽然先前的研究已将电子钙粘着蛋白描述为CTC簇中粘附的关键介体 和转移，许多乳腺肿瘤，包括高度转移性三重阴性乳腺癌的肿瘤 （TNBC），几乎没有E-Cadherin。因此，必须存在一种替代的，电子非依赖性的机制 介导CTC之间的聚类，从而促进转移和疾病进展。调查CTC 聚类机制，我们开发了一种体外肿瘤细胞聚类测定法，该测定法已包含生理 剪切力和模仿体内条件。使用此测定，我们发现电子钙粘蛋白阴性转移性乳房 癌细胞可以形成细胞相互作用，具有类似于细胞粘附连接的特征。猜测这一点 来自肿瘤细胞的细胞外基质（ECM）成分可能有助于CTC聚类，我们分析了ECM 乳腺癌亚型的成分。我们发现透明质酸合酶2（HAS2），这是主要的 负责乳腺癌细胞中透明质酸（HA）产生的酶在 TNBC。我们进一步观察到，HA介导了TNBC肿瘤细胞之间的聚类，并将其与 能够克服血液中存在的侮辱，包括剪切力。重要的是，我们检测到HA TNBC患者血液标本中相互作用CTC的细胞细胞连接处富集。从机械上讲，我们的 初步结果表明，转移性TNBC细胞上调染色质循环中的HAS2表达 由转录调节剂和推定的组蛋白赖氨酸甲基转移酶介导的机制。 总的来说，这些初步发现使我们假设在激进的TNBC中，高水平的HA 通过邻近细胞之间的HA依赖性粘合剂相互作用增强CTC聚类。我们进一步 假设PRDM6通过对HAS2表达的表观遗传调节，上调HA水平， 包括染色质循环相互作用。我们建议通过两个具体目标研究我们的假设：1） 确定HA在TNBC肿瘤细胞聚类和转移中的作用，以及2）阐明表观遗传调节 影响乳腺肿瘤细胞聚类的HAS2。为了研究我们的假设，我们将使用新颖的体外 聚类测定和体内小鼠模型以及电子显微镜，以揭示结构 CTC簇的特征。此外，我们将利用综合多态数据分析来阐明 在CTC聚类过程中，共同调节网络控制HAS2表达。重要的是，我们的结果将是 在转移性TNBC患者的血液标本中得到了广泛的验证。因此，成功完成 我们提出的工作不仅会确定一种介导强细胞相互作用的新型机制，而且还将 为识别抑制CTC聚类的新型治疗选择的机械基础铺平了基础。