ER-α 36在乳腺癌药物治疗抵抗中的新作用及其机制初步研究

发布时间：2018-08-20 08:13

【摘要】：研究背景：雌激素受体(estrogen receptor, ER)和表皮生长因子受体途径是乳腺癌细胞分裂、分化和存活等生理活动所依赖的主要信号途径。鉴于ER和人类表皮生长因子受体2(human epidermal growth factor receptor2, HER2)在乳腺癌发生、发展中的重要作用,现已发展了多种针对这些特定分子改变的乳腺癌治疗策略,其中临床最常见的是针对表达ER或孕激素受体(progesterone receptor,PR)的他莫昔芬(tamoxifen, Tam)内分泌治疗,以及针对HER2的Herceptin /Trastuzumab(中文商品名“赫赛汀”)的人源化单克隆抗体治疗。其中仅少数表达ER和PR的病人对内分泌治疗有效；Herceptin单一用药仅对低于35%的HER2过表达的转移乳腺癌病人治疗有效,并且大多数治疗有效的病人在一年之内会对药物产生抵抗。ER-a36是一种新发现的ER-a变异体,经大量实验证明ER-a36大部分定位于细胞膜和细胞浆中,主要发挥非基因组活性,ER-a36与HER2途径之间的广泛“串话(Cross-talk) "可能与Tam以及Herceptin治疗出现抵抗密切相关。Tam是一种选择性雌激素受体调节剂,最常见的内分泌治疗一线药物,但只有一半的乳腺癌患者对Tam治疗有效,即Tam抵抗在临床内分泌治疗抵抗中十分常见,是困扰临床乳腺癌治疗的一大难题,目前Tam抵抗机制尚未阐明。已有研究表明,乳腺癌细胞中ER-a66与HER2的“串话”介导的E2非基因组活性导致了对Tam的抵抗;ER-a36也可通过其非基因组活性导致对Tam的抵抗。临床资料显示近40%ER-a66阳性乳腺癌组织表达高水平的ER-α36,并增强了Tam抵抗。故推测两种受体在乳腺癌细胞中共表达可通过各自介导的非基因组活性增强Tam抵抗。Herceptin主要用于HER2阳性的乳腺癌病人治疗,Herceptin在临床抵抗常见,但其确切的机制或始发因素尚待进一步研究。鉴于HER2途径作为Herceptin治疗靶点,其可被ER-a36的非基因组活性激活,Herceptin的有效抑制剂量会增加,从而导致Herceptin疗效减弱；同时我们以前的研究证明ER-a36可通过非基因组活性影响ER阳性的乳腺癌细胞Herceptin的治疗效果。以上证据均支持ER-α36非基因组活性在乳腺癌细胞Herceptin治疗抵抗中发挥了重要作用。本课题旨在研究ER-a36在乳腺癌药物治疗抵抗中的新作用,并初步探讨其机制。研究内容：(1)采用Western blot、CCK-8、Confocal等技术研究ER-a66与其变异体ER-a36在乳腺癌中共表达对Tamoxifen疗效的影响及其机制。(2)采用Western blot、CCK-8等技术研究ER-α36对乳腺癌细胞Herceptin治疗疗效的影响及其机制。研究结果：(一)ER-a66与其变异体ER-α36在乳腺癌中共表达对Tamoxifen疗效的影响及其机制研究(1)ER-a66和ER-a36能在两者共表达的乳腺癌细胞浆/膜中共定位。(2)乳腺癌细胞中ER-α66和ER-α36的共表达可增强E2/Tam介导的MAPK和Akt磷酸化。(3)乳腺癌细胞中ER-α66和ER-α36的共表达可增强Tam刺激的细胞增殖。(二)ER-α36在Herceptin治疗抵抗中的作用及其机制研究：(1)ER-α36显著降低了Herceptin的敏感性。(2)E2通过ER-α36非基因组活性显著降低了Herceptin的敏感性。(3)E2刺激的ER-α36非基因组活性显著干扰了Herceptin抑制HER2下游信号分子MAPK和Akt磷酸化的效应。结论：(1)ER-α66与其变异体ER-α36在乳腺癌中共表达可通过各自介导的非基因组活性增强Tam抵抗。(2)ER-α36可通过非基因组活性降低乳腺癌细胞Herceptin的敏感性。研究目的和意义：(1)本课题通过对ER-α66与其变异体ER-α36在乳腺癌中共表达对Tamoxifen疗效的影响及其机制的研究可为临床Tam抵抗的研究提供一个新的重要机制,同时揭示ER-α 36可作为ER-α 66阳性的乳腺癌病人Tam治疗的重要的潜在标志物,并为临床乳腺癌病人基于Tam的联合应用治疗策略的实施提供新的理论依据。(2)通过对ER-a36在Herceptin治疗抵抗中的作用及其机制研究,可为乳腺癌细胞Herceptin治疗抵抗提供一个新的重要机制,为临床乳腺癌病人基于Herceptin的联合应用治疗策略的实施提供新的理论依据。
[Abstract]:BACKGROUND: Estrogen receptor (ER) and epidermal growth factor receptor (EGFR) pathways are the major signaling pathways for physiological activities such as cell division, differentiation and survival in breast cancer. A variety of therapeutic strategies have been developed for breast cancer with specific molecular changes. The most common clinical strategies are tamoxifen (Tam) endocrine therapy for ER or progesterone receptor (PR) expression, and human resources for HER2 (Herceptin/Trastuzumab). Chemo-monoclonal antibody therapy. Only a small number of ER-and PR-expressing patients are effective in endocrine therapy; Herceptin alone is effective in less than 35% of patients with metastatic breast cancer whose expression of ER-2 is overexpressed, and most of the patients who are effective in treatment are resistant to the drug within a year. ER-a36 is a newly discovered variant of ER-a. A large number of experiments have proved that ER-a36 is mostly located in the cell membrane and cytoplasm, mainly playing non-genomic activities. The extensive "cross-talk" between ER-a36 and HER2 pathway may be closely related to resistance to Tam and Herceptin therapy. Tam is a selective estrogen receptor modulator, the most common first-line drug for endocrine therapy. However, only half of breast cancer patients are effective in Tam therapy, i.e. Tam resistance is very common in clinical endocrine therapy resistance, which is a difficult problem for clinical breast cancer treatment. The mechanism of Tam resistance has not been clarified yet. Clinical data showed that nearly 40% of ER-a66 positive breast cancer tissues expressed high levels of ER-alpha 36 and enhanced Tam resistance. It was speculated that co-expression of the two receptors in breast cancer cells could enhance Tam resistance through their respective non-genomic activities. Herceptin resistance is common in breast cancer patients with positive HER2, but the exact mechanism or initiation of Herceptin resistance remains to be further studied. Previous studies have shown that ER-a36 can influence the therapeutic effect of ER-positive breast cancer cells Herceptin through non-genomic activity. All these evidence support that ER-a36 non-genomic activity plays an important role in the resistance of breast cancer cells to Herceptin therapy. The main contents of this study were as follows: (1) Western blot, CCK-8 and Confocal techniques were used to study the effect of ER-a66 and its variant ER-a36 co-expression on Tamoxifen in breast cancer and its mechanism. (2) Western blot, CCK-8 and other techniques were used to study the effect of ER-a66 on Herceptin treatment of breast cancer cells and its mechanism. Results: (1) The co-expression of ER-a66 and its variant ER-a36 in breast cancer could enhance the phosphorylation of MAPK and Akt mediated by E2/Tam. The co-expression of ER-alpha 66 and ER-alpha 36 in cells enhanced Tam-stimulated cell proliferation. (2) The role of ER-alpha 36 in Herceptin resistance and its mechanism: (1) ER-alpha 36 significantly decreased the sensitivity of Herceptin. (2) E2 significantly reduced the sensitivity of Herceptin through ER-alpha 36 non-genomic activity. (3) E2-stimulated ER-alpha 36 non-genomic activity. Conclusion: (1) The co-expression of ER-alpha66 and its variant ER-alpha36 in breast cancer can enhance Tam resistance through their respective non-genomic activities. (2) ER-alpha36 can reduce the sensitivity of breast cancer cells to Herceptin by non-genomic activities. Significance: (1) The study of the effect of ER-alpha 66 and its variant ER-alpha 36 co-expression on Tamoxifen in breast cancer and its mechanism may provide a new important mechanism for the study of clinical Tam resistance, and reveal that ER-alpha 36 can be used as an important potential marker of Tam therapy in ER-alpha 66 positive breast cancer patients. Tam-based combination therapy for breast cancer patients in bed provides a new theoretical basis. (2) Through the study of the role of ER-a36 in Herceptin treatment resistance and its mechanism, it can provide a new important mechanism for breast cancer cell Herceptin treatment resistance, and provide a clinical breast cancer patients with Herceptin-based combination therapy strategy. The implementation provides a new theoretical basis.
【学位授予单位】：重庆医科大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R737.9

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