TY - JOUR
T1 - miR-638 mediated regulation of BRCA1 affects DNA repair and sensitivity to UV and cisplatin in triple-negative breast cancer
AU - Tan, Xiaohui
AU - Peng, Jin
AU - Fu, Yebo
AU - An, Shejuan
AU - Rezaei, Katayoon
AU - Tabbara, Sana
AU - Teal, Christine B.
AU - Man, Yan Gao
AU - Brem, Rachel F.
AU - Fu, Sidney W.
N1 - Funding Information:
We would like to thank Dr. Kenneth H. Kraemer (NCI/NIH) for providing us with the pCMVLuc reporter gene plasmid and Dr. Wen Chen (Faculty of Preventive Medicine, School of Public Health, Sun Yat-sen University, China) for the pGL3 plasmid. We thank Woojin Lee, the W.T. Gill, Jr., Summer Research Fellow at GW School of Medicine and Health Science for qRT-PCR technical assistance. This research was supported by the Dr. Cyrus and Myrtle Katzen Cancer Research Center Grant at The George Washington University (to SWF and RFB), the National Cancer Institute Grant (1R21 CA159103-01) (to SWF), the Hao Foundation grant (to SWF) and the Elaine H. Snyder Cancer Research Award (to SWF).
Funding Information:
Acknowledgements We would like to thank Dr. Kenneth H. Kraemer (NCI/NIH) for providing us with the pCMVLuc reporter gene plasmid and Dr. Wen Chen (Faculty of Preventive Medicine, School of Public Health, Sun Yat-sen University, China) for the pGL3 plasmid. We thank Woojin Lee, the W.T. Gill, Jr., Summer Research Fellow at GW School of Medicine and Health Science for qRT-PCR technical assistance. This research was supported by the Dr. Cyrus and Myrtle Katzen Cancer Research Center Grant at The George Washington University (to SWF and RFB), the National Cancer Institute Grant (1R21 CA159103-01) (to SWF), the Hao Foundation grant (to SWF) and the Elaine H. Snyder Cancer Research Award (to SWF).
Publisher Copyright:
© 2014 Tan et al.
PY - 2014
Y1 - 2014
N2 - Introduction: Triple-negative breast cancer (TNBC) represents 15 to 20% of all types of breast cancer; however, it accounts for a large number of metastatic cases and deaths, and there is still no effective treatment. The deregulation of microRNAs (miRNAs) in breast cancer has been widely reported. We previously identified that miR-638 was one of the most deregulated miRNAs in breast cancer progression. Bioinformatics analysis revealed that miR-638 directly targets BRCA1. The aim of this study was to investigate the role of miR-638 in breast cancer prognosis and treatment. Methods: Formalin-fixed, paraffin-embedded (FFPE) breast cancer samples were microdissected into normal epithelial and invasive ductal carcinoma (IDC) cells, and total RNA was isolated. Several breast cancer cell lines were used for the functional analysis. miR-638 target genes were identified by TARGETSCAN-VERT 6.2 and miRanda. The expression of miR-638 and its target genes was analyzed by real-time qRT-PCR and Western blotting. Dual-luciferase reporter assay was employed to confirm the specificity of miR-638 target genes. The biological function of miR-638 was analyzed by MTT chemosensitivity, matrigel invasion and host cell reactivation assays. Results: The expression of miR-638 was decreased in IDC tissue samples compared to their adjacent normal controls. The decreased miR-638 expression was more prevalent in non-TNBC compared with TNBC cases. miR-638 expression was significantly downregulated in breast cancer cell lines compared to the immortalized MCF-10A epithelial cells. BRCA1 was predicted as one of the direct targets of miR-638, which was subsequently confirmed by dual-luciferase reporter assay. Forced expression of miR-638 resulted in a significantly reduced proliferation rate as well as decreased invasive ability in TNBC cells. Furthermore, miR-638 overexpression increased sensitivity to DNA-damaging agents, ultraviolet (UV) and cisplatin, but not to 5-fluorouracil (5-FU) and epirubicin exposure in TNBC cells. Host cell reactivation assays showed that miR-638 reduced DNA repair capability in post UV/cisplatin-exposed TNBC cells. The reduced proliferation, invasive ability, and DNA repair capabilities are associated with downregulated BRCA1 expression. Conclusions: Our findings suggest that miR-638 plays an important role in TNBC progression via BRCA1 deregulation. Therefore, miR-638 might serve as a potential prognostic biomarker and therapeutic target for breast cancer.
AB - Introduction: Triple-negative breast cancer (TNBC) represents 15 to 20% of all types of breast cancer; however, it accounts for a large number of metastatic cases and deaths, and there is still no effective treatment. The deregulation of microRNAs (miRNAs) in breast cancer has been widely reported. We previously identified that miR-638 was one of the most deregulated miRNAs in breast cancer progression. Bioinformatics analysis revealed that miR-638 directly targets BRCA1. The aim of this study was to investigate the role of miR-638 in breast cancer prognosis and treatment. Methods: Formalin-fixed, paraffin-embedded (FFPE) breast cancer samples were microdissected into normal epithelial and invasive ductal carcinoma (IDC) cells, and total RNA was isolated. Several breast cancer cell lines were used for the functional analysis. miR-638 target genes were identified by TARGETSCAN-VERT 6.2 and miRanda. The expression of miR-638 and its target genes was analyzed by real-time qRT-PCR and Western blotting. Dual-luciferase reporter assay was employed to confirm the specificity of miR-638 target genes. The biological function of miR-638 was analyzed by MTT chemosensitivity, matrigel invasion and host cell reactivation assays. Results: The expression of miR-638 was decreased in IDC tissue samples compared to their adjacent normal controls. The decreased miR-638 expression was more prevalent in non-TNBC compared with TNBC cases. miR-638 expression was significantly downregulated in breast cancer cell lines compared to the immortalized MCF-10A epithelial cells. BRCA1 was predicted as one of the direct targets of miR-638, which was subsequently confirmed by dual-luciferase reporter assay. Forced expression of miR-638 resulted in a significantly reduced proliferation rate as well as decreased invasive ability in TNBC cells. Furthermore, miR-638 overexpression increased sensitivity to DNA-damaging agents, ultraviolet (UV) and cisplatin, but not to 5-fluorouracil (5-FU) and epirubicin exposure in TNBC cells. Host cell reactivation assays showed that miR-638 reduced DNA repair capability in post UV/cisplatin-exposed TNBC cells. The reduced proliferation, invasive ability, and DNA repair capabilities are associated with downregulated BRCA1 expression. Conclusions: Our findings suggest that miR-638 plays an important role in TNBC progression via BRCA1 deregulation. Therefore, miR-638 might serve as a potential prognostic biomarker and therapeutic target for breast cancer.
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U2 - 10.1186/s13058-014-0435-5
DO - 10.1186/s13058-014-0435-5
M3 - Article
C2 - 25228385
AN - SCOPUS:84988888028
SN - 1465-5411
VL - 16
JO - Breast Cancer Research
JF - Breast Cancer Research
IS - 1
M1 - 435
ER -