Revealing the role of TEL/AML1 for leukemic cell survival by RNAi-mediated silencing.
Translocation (12;21), the most frequent chromosomal aberration in childhood acute lymphoblastic leukemia, creates TEL/AML1 fusion gene. Resulting hybrid protein was shown to have a role in pre-leukemia establishment. To address its role for leukemic cell survival, we applied RNA interference to silence TEL/AML1 in leukemic cells. We designed and tested 11 different oligonucleotides targeting the TEL/AML1 fusion site. Using most efficient siRNAs, we achieved an average of 74-86% TEL/AML1 protein knockdown in REH and UOC-B6 leukemic cells, respectively. TEL/AML1 silencing neither decreased cell viability, nor induced apoptosis. On the contrary, it resulted in the modest but significant increase in the S phase fraction and in higher proliferation rate. Opposite effects on cell cycle distribution and proliferation were induced by AML1 silencing, thus, supporting our hypothesis that TEL/AML1 may block AML1-mediated promotion of G1/S progression through the cell cycle. In line with the lack of major effect on phenotype, we found no significant changes in clonogenic potential and global gene expression pattern upon TEL/AML1 depletion. Our data suggest that though TEL/AML1 is important for the (pre)leukemic clone development, it may be dispensable for leukemic cell survival and would not be a suitable target for gene-specific therapy.
CLIP, Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine, Charles University Prague and University Hospital Motol, Prague, Czech Republic. marketa.zaliova@lfmotol.cuni.cz
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D002453:Cell Cycle; D045744:Cell Line, Tumor; D002470:Cell Survival; D002999:Clone Cells; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007938:Leukemia / Q000473:pathology*; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000494:pharmacology*; D000097764:ETS Translocation Variant 6 Protein
D050676:Core Binding Factor Alpha 2 Subunit; D015514:Oncogene Proteins, Fusion; D034741:RNA, Small Interfering; C102421:TEL-AML1 fusion protein; D000097764:ETS Translocation Variant 6 Protein