Upregulation of miR-181c inhibits chemoresistance by targeting ST8SIA4 in chronic myelocytic leukemia
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Lifen Zhao1, Yan Li2, Xiaobo Song3, Huimin Zhou4, Nana Li1, Yuan Miao1, Li Jia1
1College of Laboratory Medicine, Dalian Medical University, Dalian, Liaoning Province, China
2Department of Clinical Laboratory, the First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning Province, China
3Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
4Department of Microbiology, Dalian Medical University, Dalian, Liaoning Province, China
Li Jia, email: firstname.lastname@example.org
Keywords: miR-181c, ST8SIA4, chronic myelocytic leukemia, PI3K/AKT, chemoresistance
Received: April 04, 2016 Accepted: July 10, 2016 Published: August 04, 2016
Chemotherapy resistance frequently drives tumor progression. Increased expression of ST8SIA4 has been reported in diverse carcinomas and highly correlates with leukemia multidrug resistance (MDR). MicroRNAs (miRNA) are widely recognized as key players in cancer progression and drug resistance. Here, to explore whether miRNA modulates the sensitivity of chronic myelocytic leukemia (CML) to chemotherapeutic agents and regulates ST8SIA4 expression, we analyzed the complete miRNA expression profile and found a subset of miRNAs specifically dysregulated in adriamycin-resistant CML cell line K562/ADR and its parent cell line K562. Compared with three pairs of CML cell lines and 38 clinical samples of peripheral blood mononuclear cells (PBMC) of CML patients, miR-181c expression was down-regulated in drug-resistant cell lines and CML/MDR samples. Altered expression levels of miR-181c influenced the MDR phenotypes of K562 and K562/ADR. Reporter-gene assay showed that miR-181c directly targeted and inhibited the ST8SIA4 expression, as well as miR-181c was inversely correlated with the levels of ST8SIA4 expression in CML cell lines and samples. Moreover, ST8SIA4 could reverse the effect of miR-181c on drug resistance in K562 and K562/ADR cells in vitro. Upregulation of miR-181c sensitized K562/ADR cells to adriamycin in vivo through directly suppressing ST8SIA4 expression. Further investigation showed that miR-181c mediated the activity of phosphoinositide-3 kinase (PI3K)/AKT signal pathway, and inhibition of PI3K/Akt in K562 cells counteracted miR-181c-mediated MDR phenotype. These data revealed an important role for miR-181c in the regulation of chemoresistance in CML, and suggested the potential application of miR-181c in drug resistance treatment.
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