Laboratory Medicine ›› 2020, Vol. 35 ›› Issue (1): 47-55.DOI: 10.3969/j.issn.1673-8640.2020.01.011

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Role of NKX2-5 on tamoxifen resistance in breast cancer patients and its regulation mechanism

ZHAO Zheng, LI Yi, YANG Feixiang   

  1. Department of Clinical Laboratory,Dongfeng Hospital,Hubei University of Medicine,Shiyan 442000,Hubei,China
  • Received:2019-07-11 Online:2020-01-30 Published:2020-02-28

Abstract:

Objective To investigate the role of NKX2-5 on tamoxifen(TAM) resistance in breast cancer and its regulation mechanism. Methods The expressions of NKX2-5 in breast cancer tissues and adjacent tissues were determined by immunohistochemical staining assay. Using Gene Expression Omnibus(GEO) database,the relative data of breast cancer patients were analyzed,and the correlation between NKX2-5 and the survival rate of breast cancer patients was analyzed. The TAM-resistant cell lines(MCF-7/TAM) were constructed,and cell viability was determined by CCK-8 kit after the treatment with different concentrations of TAM. The expressions of the related proteins were determined by western blotting,and NKX2-5 mRNA expression was determined by reverse transcription polymerase chain reaction(RT-PCR). Results The expression of NKX2-5 was higher in adjacent tissues than that in cancer tissues(P<0.05),and NKX2-5 expression in TAM-sensitive tissues was higher than that in TAM-resistant tissues(P<0.05). Low expression of NKX2-5 was associated with poor overall survival rate and relapse free survival rate in breast cancer patients(P<0.05),and high NKX2-5 expression level also predicted better outcome for patients with TAM endocrine therapy(P<0.05). Compared to the MCF-7 cells,the expression of NKX2-5 protein was decreased in MCF-7/TAM cells(P<0.05). Overexpression NKX2-5 plasmid(Ad-NKX2-5) and empty plasmid(Ad-NC) were transfected in MCF-7/TAM cell(Ad-NKX2-5 group and Ad-NC group) by transient transfection technology. NKX2-5-small interfering RNA plasmid(NKX2-5-siRNA) and blank control(NC-siRNA) were transfected in MCF-7 cell(NKX2-5-siRNA group and NC-siRNA group). After treatment with 50 and 100 μmol/L TAM,the cell proliferation inhibition rates were increased in Ad-NKX2-5 group compared to Ad-NC group(P<0.05). The cell proliferation inhibition rates were decreased in NKX2-5-siRNA group compared to NC-siRNA group(P<0.05). The expressions of phosphorylated-P38 mitogen-activated protein kinase(p-P38MAPK),phosphorylated-c-Jun N-terminal kinase(p-JNK),phosphorylated-extracellular regulated protein kinase(p-ERK)proteins were increased in MCF-7/TAM cell compared to MCF-7 cell(P<0.05). The expressions of p-P38,p-JNK and p-ERK proteins were increased in Ad-NKX2-5 group compared to Ad-NC group(P<0.05). Meanwhile,the expression of p-P38,p-JNK and p-ERK proteins were decreased in NKX2-5-siRNA group compared to NC-siRNA group(P<0.05). Conclusions NKX2-5 is down-regulated in TAM-resistant breast cancer cell,and overexpressive NKX2-5 overcomes TAM resistance in breast cancer via suppressing mitogen-activated protein kinase(MAPK) signaling pathway.

Key words: Transcriptional factor NKX2-5, Breast cancer, Tamoxifen, Mitogen-activated protein kinase signaling pathway

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