Down.regulation of E.cadherin enhances prostate cancer chemoresistance via Notch signaling

Background:The chemoresistance of prostate cancer(PCa)is invariably associated with the aggressiveness and metastasis of this disease.New emerging evidence indicates that the epithelial-to-mesenchymal transition(EMT)may play pivotal roles in the development of chemoresistance and metastasis.As a hallmark of EMT,E-cadherin is suggested to be a key marker in the development of chemoresistance.However,the molecular mechanisms underlying PCa chemoresistance remain unclear.The current study aimed to explore the association between EMT and chemoresistance in PCa as well as whether changing the expression of E-cadherin would affect PCa chemoresistance.Methods:Parental PC3 and DU145 cells and their chemoresistant PC3-Tx R and DU145-Tx R cells were analyzed.PC3-Tx R and DU145-Tx R cells were transfected with E-cadherin-expressing lentivirus to overexpress E-cadherin;PC3 and DU145 cells were transfected with small interfering RNA to silence E-cadherin.Changes of EMT phenotype-related markers and signaling pathways were assessed by Western blotting and quantitative real-time polymerase chain reaction.Tumor cell migration,invasion,and colony formation were then evaluated by wound healing,transwell,and colony formation assays,respectively.The drug sensitivity was evaluated using MTS assay.Results:Chemoresistant PC3-Tx R and DU145-Tx R cells exhibited an invasive and metastatic phenotype that associated with EMT,including the down-regulation of E-cadherin and up-regulation of Vimentin,Snail,and N-cadherin,comparing with that of parental PC3 and DU145 cells.When E-cadherin was overexpressed in PC3-Tx R and DU145-Tx R cells,the expression of Vimentin and Claudin-1 was down-regulated,and tumor cell migration and invasion were inhibited.In particular,the sensitivity to paclitaxel was reactivated in E-cadherin-overexpressing PC3-Tx R and DU145-Tx R cells.When E-cadherin expression was silenced in parental PC3 and DU145 cells,the expression of Vimentin and Snail was up-regulated,and,particularly,the sensitivity to paclitaxel was decreased.Interestingly,Notch-1 expression was up-regulated in PC3-Tx R and DU145-Tx R cells,whereas the E-cadherin expression was down-regulated in these cells comparing with their parental cells.The use ofγ-secretase inhibitor,a Notch signaling pathway inhibitor,significantly increased the sensitivity of chemoresistant cells to paclitaxel.Conclusion:The down-regulation of E-cadherin enhances PCa chemoresistance via Notch signaling,and inhibiting the Notch signaling pathway may reverse PCa chemoresistance.

E-cadherin表达下调激活Notch信号通路增强前列腺癌化疗耐药的机制研究

背景与目的前列腺癌(prostate cancer,PCa)化疗耐药与其侵袭性和转移性密切相关。最新研究显示上皮细胞–间充质转化(epithelial-to-mesenchymal transition,EMT)可能在前列腺癌化疗耐药和转移中发挥重要作用。因此,作为EMT的标志物,E-cadherin被认为有可能与肿瘤化疗耐药有重要关系。然而,PCa化疗耐药的分子机制尚不清楚。本研究旨在探讨EMT与PCa化疗耐药的关系,以及E-cadherin表达变化是否影响PCa化疗耐药。方法以亲代PC3和DU145细胞及其化疗耐药PC3-TxR和DU145-TxR细胞作为研究对象。用E-cadherin过表达的慢病毒感染PC3-TxR和DU145-TxR细胞,使E-cadherin过表达;同时,用小干扰RNA转染PC3和DU145细胞,使E-cadherin表达沉默。采用蛋白免疫印迹和实时定量聚合酶链反应分析EMT相关标志物及信号通路的变化。分别通过划痕、transwell和克隆形成实验检测肿瘤细胞的迁移、侵袭和克隆形成能力。采用MTS法检测细胞对紫杉醇的药物敏感性。结果与亲代PC3和DU145细胞相比,化疗耐药PC3-TxR和DU145-TxR细胞表现出EMT相关的标志物表达改变,包括E-cadherin表达下调和Vimentin、Snail与N-cadherin表达上调。当E-cadherin在PC3-TxR和DU-145-TxR细胞中过表达时,Vimentin和Caldun-1表达下调,肿瘤细胞的迁移和侵袭受到抑制。特别是E-cadherin过表达以后,PC3-TxR和DU145-TxR细胞对紫杉醇的敏感性被重新激活。并且,在亲代PC3和DU145细胞中沉默E-cadherin表达后,Vimentin和Snail表达上调,对紫杉醇的敏感性降低。有趣的是,与亲代PC3和DU145细胞相比,PC3-TxR和DU145-TxR细胞中Notch-1表达上调,而E-cadherin在这些细胞中的表达下调。我们的研究还显示,Notch信号通路抑制剂γ-分泌酶抑制剂可显著增加化疗耐药细胞对紫杉醇的敏感性。结论 E-cadherin下调可以激活Notch信号通路,从而增强PCa化疗耐药,抑制Notch信号通路可能逆转PCa化疗耐药。

Effect of moxibustion on survival status and nutritional metabolic factor in tumor-bearing rats with gastric cancer

Objective:To observe the effect of moxibustion on the survival status and nutritional metabolic factors of tumor-bearing rats with gastric cancer and explore the inhibitory effect of moxibustion on the tumorbearing rats.Methods:A total of 40 SD rats were randomly divided into a blank group,a sham-operated group,a model group and a moxibustion group,10 rats in each group.Gastric cancer models were established in the model group and the moxibustion group.The rats of all the groups underwent the same constraining procedure for 20 min every day.Additionally,moxibustion was applied at acupoints for 20 min in the rats of the moxibustion group.There were two groups of acupoints.One group included"Zusanli(足三里ST 36)""Zhongwan(中脘CV12)"and"Guanyuan(关元CV4)".The other group included bilateral"Pishu(脾俞BL 20)"and"Weishu(胃俞BL 21)".Moxibustion was applied for 20 min every day at the acupoints of the two groups alternatively and lasted for 14 days.The survival status of rats was observed and the score of survival status and body weight of rats were recorded every day.At the end of intervention,the orbital blood was collected and the rats were sacrificed for sample collection.The viscera-free body weight was recorded.Using biochemical analyzer,the blood glucose(GLU),albumin(ALB),total protein(TP)and triglyceride(TG)in serum were detected.Results:(1)Regarding the score of the survival status,after modeling,the scores in the model group and the moxibustion group were all higher than those of the sham-operation group(both P<0.05).After intervention,the score in the moxibustion group was lower than that of the model group(P<0.05).(2)After modeling,the body weight in the moxibustion group and the model group was lower than those of the blank group,indicating a statistical significance(both P<0.05).The body weight in the moxibustion group was higher than that of the model group after intervention,indicating the statistical significance(P<0.05).(3)Regarding the viscera-free body weight,it was lower in the model group compared with the sham-operation group,indicating the statistical significance(P<0.05).Compared with the model group,the viscera-free body weight was higher in the moxibustion group,indicating the statistical significance(P<0.04).(4)Regarding the nutritional metabolic factors,compared with the sham-operation group,the levels of GLU and ALB in the model group were lower and TP was higher,presenting the statistical significance(all P<0.05).Compared with the model group,the levels of GLU and ALB were higher in the moxibustion group and TP was lower,presenting the statistical significance(all P<0.05).Conclusion:Moxibustion improves the survival status of tumor-bearing rats with gastric cancer,increases the body weight,the viscera-free body weight and the levels of GLU and ALB in serum and reduces TP of the tumor-bearing rats with gastric cancer and inhibits the growth of gastric cancer.