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Inhibition of Chk1 by miR-320c increases oxaliplatin responsiveness in triple-negative breast cancer.

ABSTRACT: Checkpoint kinase 1 (Chk1) expression is enhanced in most cancers owing to oncogenic activation and constant replicative stress. Chk1 inactivation is a promising cancer therapy, as its inactivation leads to genomic instability, chromosomal catastrophe, and cancer cell death. Herein, we observed that miR-320c, downregulated in triple-negative breast cancer (TNBC) patients, can target Chk1. In addition, downregulated miR-320c expression was associated with poor overall survival in TNBC patients. As Chk1 was associated with the DNA damage response (DDR), we investigated the effect of miR-320c on DDR in TNBC cells. To induce DNA damage, we used platinum-based drugs, especially oxaliplatin, which is most effective with miR-320c. We observed that overexpression of miR-320c in TNBC regulated the oxaliplatin responsiveness by mediating DNA damage repair through the negative regulation of Chk1 in vitro. Furthermore, using a xenograft model, a combination of miR-320c mimic and oxaliplatin effectively inhibited tumor progression. These investigations indicate the potential of miR-320c as a marker of oxaliplatin responsiveness and a therapeutic target to increase the efficacy of chemotherapy in TNBC.

SUBMITTER: Lim S

PROVIDER: S-EPMC7548284 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Inhibition of Chk1 by miR-320c increases oxaliplatin responsiveness in triple-negative breast cancer.

Lim Sera S Kim Yesol Y Lee Soo-Been SB Kang Hyeok-Gu HG Kim Da-Hyun DH Park Jee Won JW Chung Daeun D Kong Hyunkyung H Yoo Kyung Hyun KH Kim Yonghwan Y Han Wonshik W Chun Kyung-Hee KH Park Jong Hoon JH

Oncogenesis 20201011 10

Checkpoint kinase 1 (Chk1) expression is enhanced in most cancers owing to oncogenic activation and constant replicative stress. Chk1 inactivation is a promising cancer therapy, as its inactivation leads to genomic instability, chromosomal catastrophe, and cancer cell death. Herein, we observed that miR-320c, downregulated in triple-negative breast cancer (TNBC) patients, can target Chk1. In addition, downregulated miR-320c expression was associated with poor overall survival in TNBC patients. A ...[more]

PMID: 33041328

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Project description:Familial triple-negative breast cancers are often linked to mutations in the BRCA1 tumor suppressor gene. In sporadic triple-negative breast cancers BRCA1 is frequently inactivated at the transcriptional level, and it has been reported that this inactivation may be brought about by promoter methylation. More recently, it was found that BRCA1 may also be regulated at the post-transcriptional level by miRNAs. Here, we explored the expression of putative BRCA1-regulating miRNAs in sporadic human triple-negative breast cancer cells.Nine sporadic human breast cancer-derived cell lines and one benign breast epithelium-derived cell line were assessed for their hormone receptor, growth factor receptor and cytokeratin status by immunocytochemistry. The expression of 5 selected miRNAs predicted to target BRCA1 was assessed using qRT-PCR in the 10 cell lines. In addition, expression profiles of 84 known breast cancer-associated miRNAs were established in these 10 cell lines using PCR Array and qRT-PCR, respectively. The putative role of pre-selected candidate miRNAs in breast cancer development was assessed through exogenous expression of these miRNAs and their anti-miRNAs ('antagomirs') in MDA-MB-231 and MCF7 breast cancer-derived cells.Based on our expression profiling results, four candidate miRNAs (miR-10b, miR-26a, miR-146a and miR-153) were selected as being potentially involved in triple-negative breast cancer development. Exogenous expression assays revealed that miR-10b and miR-26a, but not miR-146a, can down-regulate the expression of BRCA1 in both triple-negative MDA-MB-231 and luminal epithelial MCF7 breast cancer-derived cells, whereas miR-153 could down-regulate BRCA1 expression only in MCF7 cells. In silico analysis of The Cancer Genome Atlas (TCGA) data confirmed that miR-146a is significantly higher expressed in triple-negative breast tumors compared to other (non triple-negative) breast tumors.Our work provides evidence for the involvement of specific miRNAs in triple-negative breast cancer development through regulating BRCA1 expression.

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Inhibition of Chk1 by miR-320c increases oxaliplatin responsiveness in triple-negative breast cancer.

Publications

Inhibition of Chk1 by miR-320c increases oxaliplatin responsiveness in triple-negative breast cancer.

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