Identification of the interaction of 2-aminosteroids with G-quadruplex in BCR/ABL gene promoter: An emerging potential target for treatment of human chronic myelogenous leukemia

Abstract

Our preliminary studies have verified that the small molecules aminosteroid could inhibit the mRNA expression of bcr/abl fusion gene in CML (Chronic Myelogenous Leukemia) cells, which may be effective in treating CML and that may have dramatically different mechanism underlying the effects by tyrosine kinase inhibitors (TKI) binding to the BCR/ABL protein. Therefore, the exact mechanism of how the aminosteroid inhibited the CML growth should be clarified and we pay our attention to the promoter domain of BCR/ABL gene to see if any interaction between aminosteroid and the promoter. First, it should be verified if G-quadruplex could be formed in BCR/ABL promoter region. Secondly, it is highly desirable to verify if aminoteroid could be interacted with the G-quadruplex structure. Here, we reported a novel therapeutic strategy based on the targeting of the G-quadruplex which formed in the promoter regions of BCR/ABL gene by aminosteroid compounds KH and BH, verified by using bioinformatics and computer simulation, UV-Vis absorption spectra, circular dichrosism(CD), fluorescence absorption spectra, fluorescence emission lifetime expenditure experiments and polymerase chain stop assays. It showed that G-quadruplex structures can be folded in BCR/ABL promoter regions and aminosteroid inhibits the mRNA expression of BCR/ABL fusion gene by stabilizing the structure of G-quadruplex, and then inhibiting the DNA replication and transcription. This demonstrates the theory that is the so-called \"chemical gene therapy\" by aminosteroid in the interaction with G-quadruplex is an emerging therapeutic protocol in treatment of chronic myeloid leukemia.