MicroRNA-1301-Mediated RanGAP1 Downregulation Induces BCR-ABL Nuclear Entrapment to Enhance Imatinib Efficacy in Chronic Myeloid Leukemia Cells

Abstract

Chronic myeloid leukemia (CML) is a myeloproliferative disease. Imatinib (IM), the first line treatment for CML, is excessively expensive and induces various side effects in CML patients. Therefore, it is essential to investigate a new strategy for improving CML therapy. Our immunoblot data revealed that RanGTPase activating protein 1 (RanGAP1) protein levels increased by approximately 30-fold in K562 cells compared with those in normal cells. RanGAP1 is one of the important components of RanGTPase system, which regulates the export of nuclear protein. However, whether RanGAP1 level variation influences BCR-ABL nuclear export is still unknown. In this report, using shRNA to downregulate RanGAP1 expression level augmented K562 cell apoptosis by approximately 40% after treatment with 250 nM IM. Immunofluorescence assay also indicated that three-fold of nuclear BCR-ABL was detected. These data suggest that BCR-ABL nuclear entrapment induced by RanGAP1 downregulation can be used to improve IM efficacy. Moreover, our qRT-PCR data indicated a trend of inverse correlation between the RanGAP1 and microRNA (miR)-1301 levels in CML patients. MiR-1301, targeting the RanGAP1 3′ untranslated region, decreased by approximately 100-fold in K562 cells compared with that in normal cells. RanGAP1 downregulation by miR-1301 transfection impairs BCR-ABL nuclear export to increase approximately 60% of cell death after treatment of 250 nM IM. This result was almost the same as treatment with 1000 nM IM alone. Furthermore, immunofluorescence assay demonstrated that Tyr-99 of nuclear P73 was phosphorylated accompanied with nuclear entrapment of BCR-ABL after transfection with RanGAP1 shRNA or miR-1301 in IM-treated K562 cells. Altogether, we demonstrated that RanGAP1 downregulation can mediate BCR-ABL nuclear entrapment to activate P73-dependent apoptosis pathway which is a novel strategy for improving current IM treatment for CML.

Prognostic microRNAs and their potential molecular mechanism in pancreatic cancer: A study based on The Cancer Genome Atlas and bioinformatics investigation

“…Fang et al ( 35 ) concluded that miR-1301-3p may function as an inhibitor of tumorigenesis, regulating cell apoptosis through B-cell lymphoma-2 (Bcl-2) and Bcl-xL in hepatocellular carcinoma HepG2 cells. Lin et al ( 36 ) indicated that miR-1301-3p-induced downregulation of Ran GTPase activating protein 1 may activate the p73-dependent apoptosis pathway by mediating breakpoint cluster region-Abelson tyrosine-protein kinase nuclear entrapment, which, may be a novel strategy for improving the current Imatinib treatment for chronic myeloid leukemia. Another study demonstrated that miR-1301-3p was upregulated in prostate cancer cells and tissues ( 37 ).…”

Resistance to Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia—From Molecular Mechanisms to Clinical Relevance

“…In Imatinib-resistant CML K562 cells (K562-RC and K562-RD cells), the oncomiRs miR-21 and miR-26b were upregulated and the tumor suppressor miR-451 was downregulated in comparison with sensitive cells [ 180 ]. Other mi-RNAs, such as miR-19a, miR-19b, miR-17, miR-130, and miR-150, are increased in CML [ 181 , 182 ]. The expression of some of these miRs is directly regulated by BCR-ABL1 through its effect on miR effectors, such as MYC in the case of miR-17 [ 183 ], CCN3 in the case of miR-130 [ 184 ], and MYB in the case of miR-150 [ 176 ].…”

The Network of Non-coding RNAs in Cancer Drug Resistance

“…miR-1301 is involved in human cancers but shows an ambiguous behavior ( 450 , 451 ). It can target the Ran GTPase Activating Protein 1 (RanGAP1) mRNA, as demonstrated by inverse correlation in CML patients: the RanGAP1 protein down-regulation or an increased miR-1301 are beneficial for the sensitivity to imatinib ( 452 ). miR-7 acts as an inhibitor in hepatocellular and pancreatic carcinomas ( 453 , 454 ) possibly regulating the PI3K/AKT pathway, which is also downstream of BCR-ABL ( 455 ).…”