The Chromosome Open Reading Frame Genes Targeted By Abnormal Micrornas in Microvesicles from Chronic Myeloid Leukemia

Object: Chronic myeloid leukemia (CML) is a paradigm for neoplasmas that are defined by a unique genetic aberration, the BCR-ABL1 fusion gene. Microvesicles (MVs) are secretory particles released by various cell types including tumor cells. MVs released by CML cells constitute an important part of the microenvironment of leukemia and can modulate the interaction of tumor cells. MicroRNAs (miRNAs) loaded within MVs may also provide an insight in the roles of miRNAs playing in pathological mechanisms of CML.

Methods:Blood samples were gathered from patients diagnosed as CML and normal heathy adults. All patients were admitted to Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology during the period from May to September in 2011. Our study was approved by the ethic committee of Wuhan Union Hospital and all subjects signed informed consent. We determined the miRNA expression profiles of CML-derived MVs using Agilent miRNA microarray analysis. Selected miRNAs obtained by microarray profiling were validated using real-time PCR. The putative target genes were predicted by bioinformatic software (TargetScan、miRanda、 PicTar、 MirTart2、PITA).

Results:We identified numerous dysregulated miRNAs in MVs derived from CML patients compared with that from the controls by microarray analysis. Of the miRNAs detected, 226 dysregulated miRNAs were present in CML-MVs.

With bioinformatic methods, we observed that there were 919 chromosome open reading frame (Corf) genes which were regulated by 169 aberrant MVs miRNAs from CML. Our results indicated that MVs derived from CML were enriched with different groups of altered miRNAs regulating Corf genes. It was interesting that some Corf genes were targeted by one aberrantly expressed MVs miRNAs and that several dysregulated miRNAs targeted one Corf gene. For example, 388 Corf genes were regulated by miR-513a-3p and 186 altered miRNAs targeted C15orf17. These findings suggested that Corf genes were active and complex in non-solid tumors.

It was suggested that some members of the Corf genes were closely associated with cancers. For instance, C1orf43, also known as NICE-3 (a novel member of epidermal differentiation complex gene), had been reported to increase tumor cell proliferation and colony formation. In addition, deletion of C8orf4 was correlated with the risk of hematological neoplasmas. Furthermore, C16orf74, negatively associated with development of malignancies, was targeted by over-expressed miR-1299. Given that miRNAs could inhibit the expression of target genes, antineoplastic functions of C16orf74 might be suppressed. Similarly, C11orf30 that was a key oncogene was targeted by down-expressed miR-93, which facilitated C11orf30 to produce tumor-promoting roles. Interestingly, we observed that several Corf genes acting as oncogenes were regulated by over-expressed miRNAs. For instance, C6orf211 and C19orf10 were positively correlated with tumor progression and both of them were regulated by up-regulated miRNAs including miR-1246 and miR-1305. This indicated that Corf genes in diverse tumor microenvironments were likely to exert different influence on carcinogenesis.

Conclusion: Briefly, we demonstrated for the first time that CML-derived MVs were enriched with dysregulated miRNAs targeting Corf genes, indicating that miRNAs regulating Corf genes were active in CML-MVs. Furthermore, Corf genes regulated by distinct sets of altered miRNAs might produce similar or alien effects on tumor progression.