Identificación y estudio de RNAs largos no codificantes cuya expresión está alterada en la leucemia aguda linfoblástica

Resum

STUDY AND IDENTIFICATION OF lncRNAs WHICH EXPRESSION IS ALTERED IN ACUTE LYMPHOBLASTIC LEUKEMIA Andoni Garitano Trojaola. Faculty of Sciences. University of Navarra. 2015 Long non-coding RNAs (lncRNAs) are functional RNAs longer than 200 nucleotides in length. Compared to mRNAs, most lncRNAs are localized preferentially to the nucleus, are more cell type specific and are expressed at lower levels. The function of lncRNAs in the cell is primarily regulatory and they have a clear impact in cell behavior. Furthermore, several lncRNAs are deregulated in human diseases including several cancers. For these reasons and the important role of other non-coding RNAs like miRNAs in Acute Lymphoblastic Leukemia (ALL), we decided to analyze the expression and function of lncRNAs in ALL. In order to identify aberrantly expressed lncRNAs in ALL, we used the SurePrint G3 Human Gene Expression array that detects 27956 coding genes and 7419 lncRNAs. The transcriptomes of primary ALL cells, ALL cell lines and control samples were compared. In this analysis, we detected 37 lncRNAs differentially expressed, 24 of them down-regulated and 13 up-regulated in ALL cells compared to healthy controls. We analyzed the expression of 21 deregulated lncRNAs by quantitative RT-PCR (q-PCR) and we validated the data obtained by expression arrays in 18 out of the 21 genes tested. We focused our study in MEG3 and linc-PINT, and by q-PCR, we observed a decreased expression of these 2 lncRNAs in 10 ALL-derived cell lines compared with B and T cells obtained from healthy donors. Also, we detected a direct correlation between an inappropriate DNA methylation and the decreased expression of MEG3 in ALL cell lines. Interestingly, we observed that re-expression of MEG3 or linc-PINT in ALL cells led to a decrease in cell proliferation, due to cell cycle arrest in G2 phase and induction of apoptosis. The transcriptome analysis of ALL cell lines after overexpression of MEG3 or linc-PINT, showed an increase expression of HMOX1. Interestingly, the overexpression of HMOX1 on its own also decreased cell proliferation, suggesting that HMOX1 could be a mediator of the phenotype observed after re-expression of MEG3 or linc-PINT. Finally, we observed that different drugs that affect proliferation of ALL cells, such as curcumin or panobinostat, induced drastically the expression of linc-PINT and HMOX in these cell lines. These results indicate that linc-PINT and HMOX1 could be interesting therapeutic targets for improving the treatment of ALL patients. The expression of several lncRNAs is altered in primary samples and cell lines of ALL. In some cases, altered expression is due to inappropriate DNA methylation. MEG3 and linc-PINT are decreased in ALL cells and their re-expression affects cell cycle progression and induces apoptosis in these cells. These effects could be mediated by HMOX. Curcumin and panobinostat also induce linc-PINT and HMOX, which could drive their effects in cell proliferation. Therefore, linc-PINT and HMOX1 could be therapeutic targets for improving the treatment of patients with ALL.