Identification of predictive factors of adjuvant chemotherapy for breast cancer

研究背景：紫杉烷类药物是治疗乳腺癌的重要药物。这些药物与微管蛋白结合并抑制纺锤体微管动力学，这导致细胞周期停滞在G2/M期，随后发生凋亡。然而，对紫杉烷治疗的耐药性阻止了一些患者从这些药物中获益。紫杉烷耐药的几种机制已被描述，包括微管相关蛋白-tau（MAPT）的参与。MAPT与微管中的紫杉烷结合到相同的口袋中，并阻碍药物的功能。雌激素受体（ER）是一种转录因子，在乳腺癌的发生和发展中起重要作用。然而，ER和MAPT在乳腺癌中的关系并不完全清楚。在这项研究中，我们研究了MAPT表达和人乳腺癌细胞对紫杉烷类药物的敏感性之间的相关性，以及这些细胞中ER和MAPT在蛋白水平上的关系。我们还检查了联合治疗， ...更多信息 激素类药物和紫杉烷类药物。研究方法：采用真实的时间PCR、蛋白质印迹分析和MTS分析检测了12个人乳腺癌细胞系中MAPT表达与紫杉烷类药物敏感性之间的相关性。用小干扰RNA（siRNA）敲低MAPT表达后，用MTS法、流式细胞术和免疫荧光法检测细胞对紫杉烷类药物敏感性的变化。为了检查ER和MAPT之间的关系，在MAPT和ER阳性细胞系（分别为MCF-7和ZR 75.1）中用siRNA敲低ER表达或用17-β-雌二醇刺激ER表达。还用激素药物（他莫昔芬和ICI 182，780）处理细胞，并检查MAPT蛋白表达的变化。结果如下：六个细胞系显示高MAPT mRNA表达和四个显示高MAPT蛋白表达，也就是说，在mRNA水平上的表达并不总是与在蛋白质水平上的表达相关。MAPT mRNA的表达与紫杉烷耐药无关，但70 kDa以下的MAPT蛋白亚型的表达与紫杉烷耐药相关。MAPT的下调增加了对紫杉烷的敏感性。MAPT蛋白表达在ER敲低时降低，在17-β-雌二醇刺激时增加。MAPT蛋白水平也被他莫昔芬增加，但被IC 1182，780降低。紫杉烷类与ICI 182，780的组合处理显示出强的协同作用，但与他莫昔芬的类似处理在两种细胞系中具有拮抗作用。结论：MAPT蛋白70 kDa以下亚型的表达与乳腺癌细胞紫杉烷耐药相关。乳腺癌中MAPT表达受ER影响，选择性ER抑制剂ICI 182，780可逆转MAPT和ER阳性乳腺癌对紫杉烷类的耐药性。少

Background : Taxanes are important drugs in treatment of breast cancer. These drugs bind to tubulin and suppress spindle microtubule dynamics, which leads to cell cycle arrest in the G2/M phase followed by apoptosis. However, resistance to taxane therapy prevents some patients from benefiting from these drugs. Several mechanisms of taxane resistance have been described, including the involvement of microtubule-associated protein-tau (MAPT). MAPT binds to the same pocket as taxanes in microtubules and obstructs the function of the drug. Estrogen receptors (ER) are transcriptional factors that play an important role in the development and progression of breast cancer. However, the relationship between ER and MAPT in breast cancer is not entirely clear. In this study we examined the correlation between MAPT expression and the sensitivity of human breast cancer cells to taxanes, and the relationship between ER and MAPT at the protein level in these cells. We also examined combination thera … More py with hormone drugs and taxanes. Methods : The correlation between MAPT expression and sensitivity to taxanes was examined in 12 human breast cancer cell lines using real time PCR, western blotting analysis and an MTS assay. Following small interfering RNA (siRNA) knockdown of MAPT expression, the alteration of cellular sensitivity to taxanes was examined by MTS assay, flow cytometry and immunofluorescence. To examine the relationship between ER and MAPT, ER expression was knocked down with siRNA or stimulated with 17-β-estradiol in MAPT- and ER-positive cell lines (MCF-7 and ZR75.1, respectively). The cells were also treated with hormone drugs (tamoxifen and ICI182,780) and changes in MAPT protein expression were examined. Results : Six cell lines showed high MAPT mRNA expression and four showed high MAPT protein expression ; that is, expression at the mRNA level did not always correlate with that at the protein level. MAPT mRNA expression did not correlate with taxane resistance, but expression of MAPT protein isoforms under 70kDa correlated with taxane resistance. Downregulation of MAPT increased sensitivity to taxanes. MAPT protein expression was decreased by ER knockdown and increased by 17-β-estradiol stimulation. The MAPT protein level was also increased by tamoxifen, but decreased by IC1182,780. Combination treatment of taxanes with ICI182,780 showed a strong synergistic effect, but similar treatment with tamoxifen had an antagonistic effect in both cell lines. Conclusions : Expression of MAPT protein isoforms under 70kDa correlates with taxane resistance in breast cancer cells. MAPT expression is influenced by ER in breast cancer and ICI182,780, a selective ER inhibitor, can reverse the resistance to taxanes in both MAPT- and ER-positive breast cancer. Less