Bourguignon Lilly Y W, Wong Gabriel, Shiina Marisa
From the Endocrine Unit, Department of Medicine, University of California at San Francisco and San Francisco Veterans Affairs Medical Center, San Francisco, California 94121
From the Endocrine Unit, Department of Medicine, University of California at San Francisco and San Francisco Veterans Affairs Medical Center, San Francisco, California 94121.
J Biol Chem. 2016 May 13;291(20):10571-85. doi: 10.1074/jbc.M115.700021. Epub 2016 Mar 21.
Human head and neck squamous cell carcinoma is a solid tumor malignancy associated with major morbidity and mortality. In this study, we determined that human head and neck squamous cell carcinoma-derived HSC-3 cells contain a subpopulation of cancer stem cells (CSCs) characterized by a high level of CD44v3 and aldehyde dehydrogenase-1 (ALDH1) expression. Importantly, matrix hyaluronan (HA) induces the up-regulation of stem cell markers that display the hallmark CSC properties. Histone methyltransferase, DOT1L, is also up-regulated by HA in CSCs (isolated from HSC-3 cells). Further analyses indicate that the stimulation of microRNA-10b (miR-10b) expression is DOT1L-specific and HA/CD44-dependent in CSCs. This process subsequently results in the overexpression of RhoGTPases and survival proteins leading to tumor cell invasion and cisplatin resistance. Treatment of CSCs with DOT1L-specific small interfering RNAs (siRNAs) effectively blocks HA/CD44-mediated expression of DOT1L, miR-10b production, and RhoGTPase/survival protein up-regulation as well as reduces tumor cell invasion and enhances chemosensitivity. CSCs were also transfected with a specific anti-miR-10b inhibitor to silence miR-10b expression and block its target functions. Our results demonstrate that the anti-miR-10 inhibitor not only decreases RhoGTPase/survival protein expression and tumor cell invasion, but also increases chemosensitivity in HA-treated CSCs. Taken together, these findings strongly support the contention that histone methyltransferase, DOT1L-associated epigenetic changes induced by HA play pivotal roles in miR-10 production leading to up-regulation of RhoGTPase and survival proteins. All of these events are critically important for the acquisition of cancer stem cell properties, including self-renewal, tumor cell invasion, and chemotherapy resistance in HA/CD44-activated head and neck cancer.
人头颈部鳞状细胞癌是一种与高发病率和死亡率相关的实体瘤恶性肿瘤。在本研究中，我们确定人头颈部鳞状细胞癌来源的HSC-3细胞包含一个癌症干细胞（CSC）亚群，其特征在于高水平的CD44v3和醛脱氢酶-1（ALDH1）表达。重要的是，基质透明质酸（HA）诱导显示典型CSC特性的干细胞标志物上调。组蛋白甲基转移酶DOT1L在CSC（从HSC-3细胞分离）中也被HA上调。进一步分析表明，在CSC中，微小RNA-10b（miR-10b）表达的刺激是DOT1L特异性的且依赖于HA/CD44。这一过程随后导致RhoGTP酶和存活蛋白的过表达，从而导致肿瘤细胞侵袭和顺铂耐药。用DOT1L特异性小干扰RNA（siRNA）处理CSC可有效阻断HA/CD44介导的DOT1L表达、miR-10b产生以及RhoGTP酶/存活蛋白上调，同时减少肿瘤细胞侵袭并增强化学敏感性。还用特异性抗miR-10b抑制剂转染CSC以沉默miR-10b表达并阻断其靶功能。我们的结果表明，抗miR-10抑制剂不仅降低RhoGTP酶/存活蛋白表达和肿瘤细胞侵袭，还增加HA处理的CSC中的化学敏感性。综上所述，这些发现有力地支持了这样的观点，即HA诱导的组蛋白甲基转移酶DOT1L相关的表观遗传变化在miR-10产生中起关键作用，导致RhoGTP酶和存活蛋白上调。所有这些事件对于获得癌症干细胞特性至关重要，包括在HA/CD44激活的头颈癌中的自我更新、肿瘤细胞侵袭和化疗耐药。
