乳酸脱氢酶LDHB基因异常表达在三阴乳腺癌中的作用和调控机制研究

Breast cancer is a “leading killer” of women, which serious harms to female health. The triple negative breast cancer (TNBC) is the most malignant subtype among all types of breast cancer. Probably because of lacking of specific molecular markers, TNBC is difficult to quickly and effectively to get diagnosis and targeted treatment. Hence, screening and study in TNBC molecular markers is the key to its prevention and treatment. Different from the non-TNBC, TNBC has significantly increased glycolysis. Previous studies found that the lactic acid dehydrogenase B (LDHB), which catalyzed the lactic acid production in glycolysis pathway, showed a distinct increased expression and played a vital role in TNBC. But the regulatory mechanism of increased LDHB expression in TNBC is still unclear. By population sequence screening, we found that there have some high frequency mutations which proved to lead higher gene expression in TNBC. Given these, aiming at the high frequency mutations of LDHB promoter in TNBC, this project intends to explore the roles of these mutations in vivo and in vitro; then we further investigate the regulation mechanism through EMSA and transcriptome sequencing. Research results will helpful to our further understanding to the significantly increased glycolysis in TNBC, and also provided new molecular markers for its prevention and early treatment.

乳腺癌是威胁女性健康的“头号杀手”，其中三阴乳腺癌（TNBC）的恶性程度最高。但由于缺乏特有的阳性分子标记，导致TNBC难以快速、有效地得到诊断并进行针对性治疗。因此，筛查研究TNBC的分子标记是对其开展预防和治疗的关键。与非三阴乳腺癌相比，TNBC糖酵解作用显著增强，而前期研究确实发现糖酵解中催化乳酸生成的乳酸脱氢酶B（LDHB）异常高表达在TNBC中起关键作用，但其调控机制不明。我们基于人群筛查发现，TNBC患者的LDHB启动子区存在显著高频突变且初步实验揭示其能促使基因表达上调，提示TNBC中显著增强的糖酵解能力很可能存在遗传学基础。鉴于此，本项目针对前期筛选出的高频突变，拟在体内外研究其对TNBC细胞增殖、侵袭等方面的作用；进而利用EMSA和转录组测序，研究其对基因表达的调控机制。研究结果将有助于深入理解TNBC中糖酵解显著增强的遗传机制，为其预防和早期诊断提供新的分子标记。

三阴性乳腺癌(TNBC)是一种侵袭性和致命性疾病，但目前尚缺乏有效的分子生物学标志物用于早期诊断和预防。先前的研究表明乳酸脱氢酶-B(LDHB)基因在TNBC中高表达。因此，我们检测了LDHB是否具有可作为TNBC预测生物标记物的基因突变。为本研究对90名TNBC患者、110名非TNBC患者和169名健康对照的LDHB基因启动子区进行了全序列测定。此外，我们使用双荧光素酶报告实验来检测野生型和突变型LDHB启动子中的基因表达水平。分析发现LDHB的一个SNP位点(Rs11046147)在TNBC中显著富集(53/90，58.9%)，显著高于非TNBC(31/110，28.2%)和健康人群(27/169，16.0%)。双荧光素酶报告实验也表明rs11046147突变(G>A)增强了LDHB启动子的活性。我们进一步鉴定了几个与突变的LDHB启动子特异结合的转录因子，这可能是LDHB表达增强的潜在机制。此外，LDHB启动子区域的这种突变有可能成为TNBC的潜在预测生物标志物。