miR-155 effectively induces apoptosis in K562 Philadelphia positive cell line through upregulation of p27kip1

Chronic myelogenous leukemia (CML) is a myeloproliferative disorder caused by the Philadelphia chromosome translocation, at (9; 22), which results in BCR-ABL fusion tyrosine kinase oncoprotein. This fusion induces down-regulation of miR-155. Upregulation of miR-155 can influence cell fate via the effect on p27kip1 and apoptosis. The aim of this study was to induce apoptosis in K562 CML cell line by overexpression of miR- 155. Methods: The K562 cell line was transfected with pLenti-III-pre mir155-GFP constructs through electroporation. Then, overexpression of miR-155 as well as the expression level of p27kip1 and c-Myc was analyzed by quantitative PCR (qPCR). The level of p27 (Kip1) protein expression was measured by Western blot and the Annexin V method was carried out to investigate apoptosis. Results: Flow cytometric analysis results of K562 cells transfected with pLenti-III-pre mir155- GFP construct showed a significant increase in cell apoptosis. Gene expression and protein level of p27kip1 were upregulated. However, there was no change in c-Myc expression profile. Conclusion: miR-155 could be a promising approach to aid in the treatment of CML. However, further studies are required in this respect.