MicroRNA-21 modulates chemosensitivity of breast cancer cells to doxorubicin by targeting PTEN.

BACKGROUND AND AIMS Ovexpression of microRNA-21 (miR-21) is found in various human cancers. Our aim is to investigate the association of miR-21 expression with the sensitivity of breast cancer cells to doxorubicin (ADR). METHODS The half maximal inhibitory concentration (IC(50)) value of ADR in resistant MCF-7/ADR or parental MCF-7 cells was determined by MTT assay. TaqMan RT-PCR or Western blot assay was performed to detect the expression of mature miR-21 and tumor suppressor gene (PTEN) protein. MCF-7 or MCF-7/ADR cell line was transfected with miR-21mimic or inhibitor. The IC(50) value of ADR was determined. Flow cytometry and TUNEL assays were performed to analyze apoptosis. The activity of caspase-3 was analyzed. RESULTS The IC(50) of ADR in MCF-7 and MCF-7/ADR cells was 0.21 ± 0.05 and 16.5 ± 0.08 μmol/L, respectively. We showed that upregulation of miR-21 in MCF-7/ADR cells was concurrent with downregulation of PTEN protein. MiR-21 mimic or inhibitor could obviously affect the sensitivity of breast cancer cells to ADR. Moreover, miR-21 inhibitor could enhance caspase-3-dependent apoptosis in MCF-7/ADR cells. Overexpression of PTEN could mimic the same effects of miR-21 inhibitor in MCF-7/ADR cells and PTEN-siRNA could increase the resistance of MCF-7 cells to ADR. MiR-21 inhibitor could increase PTEN protein expression and the luciferase activity of a PTEN 3' untranslated region-based reporter construct in MCF-7/ADR cells. PTEN-siRNA could partially reverse the increased chemosensitivity of MCF-7/ADR cells induced by miR-21 inhibitor. CONCLUSIONS Dysregulation of miR-21 plays critical roles in the ADR resistance of breast cancer, at least in part via targeting PTEN.

[1]  A. Jemal,et al.  Cancer Statistics, 2009 , 2009, CA: a cancer journal for clinicians.

[2]  Y. Takeda,et al.  MicroRNA-21 induces resistance to the anti-tumour effect of interferon-α/5-fluorouracil in hepatocellular carcinoma cells , 2010, British Journal of Cancer.

[3]  Shuomin Zhu,et al.  miR-21-mediated tumor growth , 2007, Oncogene.

[4]  K. Ghoshal,et al.  MicroRNA-21 regulates expression of the PTEN tumor suppressor gene in human hepatocellular cancer. , 2007, Gastroenterology.

[5]  Subbaya Subramanian,et al.  MicroRNAs as gatekeepers of apoptosis , 2010, Journal of cellular physiology.

[6]  Yandan Yao,et al.  MiR-21 Indicates Poor Prognosis in Tongue Squamous Cell Carcinomas as an Apoptosis Inhibitor , 2009, Clinical Cancer Research.

[7]  Li Xie,et al.  MicroRNA-21 regulates breast cancer invasion partly by targeting tissue inhibitor of metalloproteinase 3 expression , 2010, Journal of experimental & clinical cancer research : CR.

[8]  Thomas Tuschl,et al.  miRNAs in human cancer , 2011, The Journal of pathology.

[9]  A. Krogh,et al.  Programmed Cell Death 4 (PDCD4) Is an Important Functional Target of the MicroRNA miR-21 in Breast Cancer Cells* , 2008, Journal of Biological Chemistry.

[10]  Shuomin Zhu,et al.  MicroRNA-21 targets tumor suppressor genes in invasion and metastasis , 2008, Cell Research.

[11]  X. Agirre,et al.  MicroRNAs as cancer players: potential clinical and biological effects. , 2007, DNA and cell biology.

[12]  Ugo Boggi,et al.  MicroRNA-21 in pancreatic cancer: correlation with clinical outcome and pharmacologic aspects underlying its role in the modulation of gemcitabine activity. , 2010, Cancer research.

[13]  B. Qian,et al.  High miR-21 expression in breast cancer associated with poor disease-free survival in early stage disease and high TGF-β1 , 2009, Breast Cancer Research and Treatment.

[14]  H. Iwase,et al.  [Breast cancer]. , 2006, Nihon rinsho. Japanese journal of clinical medicine.

[15]  Taous Khan,et al.  MicroRNAs: synthesis, mechanism, function, and recent clinical trials. , 2010, Biochimica et biophysica acta.

[16]  D. Dykxhoorn.  MicroRNAs and metastasis: little RNAs go a long way. , 2010, Cancer research.

[17]  Sota Asaga,et al.  Direct serum assay for microRNA-21 concentrations in early and advanced breast cancer. , 2011, Clinical chemistry.

[18]  Lei Shi,et al.  MiR-21 protected human glioblastoma U87MG cells from chemotherapeutic drug temozolomide induced apoptosis by decreasing Bax/Bcl-2 ratio and caspase-3 activity , 2010, Brain Research.

[19]  C. Croce,et al.  Roles of small RNAs in tumor formation. , 2010, Trends in molecular medicine.

[20]  Guanghai Yang,et al.  MicroRNA-21 (miR-21) represses tumor suppressor PTEN and promotes growth and invasion in non-small cell lung cancer (NSCLC). , 2010, Clinica chimica acta; international journal of clinical chemistry.

[21]  Y. Shu,et al.  MiR-21 overexpression in human primary squamous cell lung carcinoma is associated with poor patient prognosis , 2011, Journal of Cancer Research and Clinical Oncology.

[22]  J. Fei,et al.  miRNA-21 regulates arsenic-induced anti-leukemia activity in myelogenous cell lines , 2011, Medical oncology.

[23]  Guan-li Huang,et al.  Clinical significance of miR-21 expression in breast cancer: SYBR-Green I-based real-time RT-PCR study of invasive ductal carcinoma. , 2009, Oncology reports.

[24]  Qiong Shao,et al.  MicroRNA miR-21 overexpression in human breast cancer is associated with advanced clinical stage, lymph node metastasis and patient poor prognosis. , 2008, RNA.

[25]  J. Fei,et al.  Anti-miR-21 oligonucleotide enhances chemosensitivity of leukemic HL60 cells to arabinosylcytosine by inducing apoptosis , 2010, Hematology.

[26]  Zhongwei Cao,et al.  Involvement of miR‐21 in resistance to daunorubicin by regulating PTEN expression in the leukaemia K562 cell line , 2011, FEBS letters.

[27]  X. Yao,et al.  Involvement of microRNA-21 in mediating chemo-resistance to docetaxel in androgen-independent prostate cancer PC3 cells , 2010, Acta Pharmacologica Sinica.