Study On The Role And Mechanism Of EZH2 In The Early Diagnosis Of Prostate Cancer And The Drug Resistance Of Castration Resistant Prostate Cancer

Objective: To reveal the possible clinical value of EZH2 in prostatic fluid in the diagnosis of prostate cancer,and to provide new ideas for the diagnosis of non-invasive prostate cancer.To explore the role and mechanism of EZH2 in resistance to docetaxel in prostate cancer.Methods: Prostate fluid from patients with suspected prostate cancer was collected and grouped according to the pathological results.The expression of EZH2 in different groups of prostatic fluid was detected by RT-PCR and enzyme-linked immunosorbent assay(ELISA),and then analysis the expression of EZH2 in early stage of prostate cancer with the clinical value of diagnosis,and the relationship among the clinicopathological characteristics.The drug-resistant cell line,PC-3 / DR,was constructed by intermittent increasing concentration method and then the expression of EZH2 m RNA and protein was detected by real-time quantitative PCR and western blotting(WB).The effects of EZH2 on the migration,invasion,apoptosis and proliferation of drug-resistant cells were also tested by flow cytometry and MTT assay,alone or in combination with docetaxel.Then,PC-3 / DR cells and EZH2 stably transfected PC-3 / DR cells were subcutaneously injected into nude mice to establish a tumor-bearing mouse model and observe the effect of RNAi combined with docetaxel on the tumor,weight and other effects.Finally,the protein expression of EZH2,H3-(me)3-K27 and Bcl-2 in the tumor was detected by immunohistochemistry and Western bloting.Results: The concentration of EZH2 in prostate cancer group was significantly higher than that in prostatitis group(P <0.05),benign prostatic hyperplasia group(P <0.05)and normal group(P < 0.001).Prostatitis group,benign prostatic hyperplasia group and the normol gruop have no significant difference.The expression of EZH2 in prostate cancer patients was not related to the clinical stage,but there was a significant difference among different pathological grades(P < 0.01).When the expression of EZH2 was higher,the severe about the prostate cancer differentiation was more.The ROC curve area of relative quantitative value of EZH2 m RNA was higher than the area under PSA curve.When the relative content of EZH2 m RNA was 0.66,the diagnostic efficiency was the highest.Realtime quantitative PCR and Western blotting showed that the expression level of EZH2 in drug-resistant strains was significantly higher than that in non-drug-resistant cells(P < 0.01).EZH2 overexpression promoted cell resistance,while inhibition of EZH2 expression reversed drug resistance(P <0.01).In addition,the increased expression of EZH2 significantly increased cell migration and invasion,inhibited cell apoptosis and promoted cell proliferation(P <0.01),and the combined effect of RNAi and docetaxel was higher than that of RNAi alone or Docetaxel alone(P <0.001).In vivo results showed that inhibition of EZH2 expression significantly inhibited the growth of drug-resistant tumor(P <0.05).In addition,the combination of RNAi and docetaxel tumor inhibition rate was higher than the single application(P <0.001).Immunohistochemistry or Westerblot showed that the expression of H3-(me)3-K27 and Bcl-2 in the tumor tissues were significantly decreased after EZH2 was inhibited(P <0.01).Conclusion: The detection of EZH2 in prostatic fluid has high sensitivity and specificity for the early diagnosis of prostate cancer,which has a good prospect as a diagnostic indicator of prostate cancer.Elevated EZH2 expression plays an important role in resistance to docetaxel in prostate cancer.Inhibition of EZH2 expression can reduce drug resistance,and the combined use of RNAi and docetaxel,which can reverse the drug resistance,are the most obvious in the test.EZH2 may cause cell resistance by regulating the high expression of H3-(me)3-K27 and Bcl-2.