Recently,a large number of tyrosine kinase inhibitors(TKIs) have been developed as anticancer agents.These TKIs can specifically and selectively inhibit tumor cell growth and metastasis by targeting various tyrosine kinases and thereby interfering with cellular signaling pathways.The therapeutic potential of TKIs has been hindered by multidrug resistance(MDR),which is commonly caused by overexpression of ATP-binding cassette(ABC) membrane transporters.Interestingly,some TKIs have also been found to reverse MDR by directly inhibiting the function of ABC transporters and enhancing the efficacy of conventional chemotherapeutic drugs.In this review,we discuss ABC transporter-mediated MDR to TKIs and MDR reversal by TKIs.
脯氨酸-谷氨酸-亮氨酸富集蛋白1/雌激素受体非基因组活性辅助调节因子(proline-,glutamic acid-,leucine-rich protein 1/modulator of nongenomic activity of estrogen receptor,PELP1/MNAR)是一种新近发现的核受体辅助活化因子,具有较为复杂的分子结构,在多种组织中广泛表达。与先前发现的核受体辅助调节因子不同的是:作为一种支架蛋白,PELP1/MNAR既参与核受体调控靶基因转录的基因组作用,又参与了核受体激活激酶信号系统的非基因组作用,并且可能在核受体信号与生长因子信号串话(cross talk)中发挥重要作用。近年的研究表明,PELP1/MNAR在乳腺癌、卵巢癌、子宫内膜癌、前列腺癌等激素依赖性肿瘤中均有异常表达和分布,在激素依赖性肿瘤的发生、发展、转移、耐药形成过程中可能具有重要意义,可望成为内分泌依赖性肿瘤治疗的一个新的靶点。
Objective： To better understand the contribution of dysregulated DNA methyltransferase 1 （DNMT1） expression to the progression and biology of clear cell renal cell carcinoma （ccRCC）. Methods： We examined the differences in the expression of DNMT1 in 89 ecRCC and 22 normal tissue samples by immunohistochemistry. In addition, changes in cell viability, apoptosis, colony formation and invading ability of ccRCC cell lines （786-0 and Caki-1） were assessed after transfection with DNMT1 siRNA. Results： We found DNMT1 protein was significantly higher expressed in ccRCC than that of in no-tumor tissues （56.2% and 27.3%, respectively, P=0.018）. The expression of DNMT1 was strongly associated with ccRCC tumor size, tumor pathology stage, histological grading, lymph node metastasis, vascular invasion, recurrence and prognosis. Moreover, knockdown of DNMT1 expression significantly inhibited ccRCC cell viability, induced apoptosis, decreased colony formation and invading ability. Conclusions： Expression of DNMTI protein is increased in ccRCC tissues, and DNMT1 expression is associated with poor prognosis of patients. Experiments in vitro further showed DNMT1 played an essential role in proliferation and invasion of renal cancer cells. Moreover, targeting this enzyme could be a promising strategy for treating ccRCC, as evidenced by inhibited cell viability, increased apoptosis, decreased colony formation and invading ability.
Ming LiYing WangYongsheng SongRenge BuBo YinXiang FeiQizhen GuoBin Wu
