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Tumour Biol. 2016 Nov;37(11):15315-15324. Epub 2016 Oct 4.

miR-222 induces Adriamycin resistance in breast cancer through PTEN/Akt/p27kip1 pathway.

Author information

1
Department of General Surgery, Jiangsu Cancer Hospital Affiliated to Nanjing Medical University, Baiziting 42, Nanjing, 210009, China.
2
Center of Clinical Laboratory Science, Jiangsu Cancer Hospital Affiliated to Nanjing Medical University, Baiziting 42, Nanjing, 210009, China.
3
Center of Clinical Laboratory Science, Jiangsu Cancer Hospital Affiliated to Nanjing Medical University, Baiziting 42, Nanjing, 210009, China. jsccljhzhao@126.com.
4
Department of General Surgery, Jiangsu Cancer Hospital Affiliated to Nanjing Medical University, Baiziting 42, Nanjing, 210009, China. jinhangtangjsch@163.com.

Abstract

The high resistant rate of Adriamycin (Adr) is associated with a poor prognosis of breast cancer in women worldwide. Since miR-222 might contribute to chemoresistance in many cancer types, in this study, we aimed to investigate its efficacy in breast cancer through PTEN/Akt/p27 kip1 pathway. Firstly, in vivo, we verified that miR-222 was upregulated in chemoresistant tissues after surgery compared with the paired preneoadjuvant samples of 21 breast cancer patients. Then, human breast cancer Adr-resistant cell line (MCF-7/Adr) was constructed to validate the pathway from the parental sensitive cell line (MCF-7/S). MCF-7/Adr and MCF-7/S were transfected with miR-222 mimics, miR-222 inhibitors, or their negative controls, respectively. The results showed that inhibition of miR-222 in MCF-7/Adr significantly increased the expressions of PTEN and p27 kip1 and decreased phospho-Akt (p-Akt) both in mRNA and protein levels (p < 0.05) by using quantitative real-time PCR (qRT-PCR) and western blot. MTT and flow cytometry suggested that lower expressed miR-222 enhanced apoptosis and decreased the IC50 of MCF-7/Adr cells. Additionally, immunofluorescence demonstrated that the subcellular location of p27 kip1 was dislocated resulting from the alteration of miR-222. Conversely, in MCF-7/S transfected with miR-222 mimics, upregulation of miR-222 is associated with decreasing PTEN and p27 kip1 and increasing Akt accompanied by less apoptosis and higher IC50. Importantly, Adr resistance induced by miR-222 overexpression through PTEN/Akt/p27 was completely blocked by LY294002, an Akt inhibitor. Taken together, these data firstly elucidated that miR-222 could reduce the sensitivity of breast cancer cells to Adr through PTEN/Akt/p27 kip1 signaling pathway, which provided a potential target to increase the sensitivity to Adr in breast cancer treatment and further improved the prognosis of breast cancer patients.

KEYWORDS:

Adr resistance; Breast cancer; PTEN/Akt/p27 pathway; miR-222

PMID:
27699665
DOI:
10.1007/s13277-016-5341-2
[Indexed for MEDLINE]

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