Because the PCR detection of the AML1/MTG8(ETO) fusion at the RNA level is highly sensitive, it can be used as a sensitive method for diagnosis and detection of minimal residual disease in t(8;21) leukemia.
AML1/ETO fusion transcripts were neither found in the PB and BM of a healthy individual, nor in the PB of a patient after allogeneic BMT for cytogenetically proven t(8;21)-leukemia.
The t(8;21) creates a fusion protein between AML-1 and a gene of unknown function, mtg8 (ETO), whereas the t(12;21) fuses the TEL (translocation-ets-leukemia) transcription factor to the N-terminus of AML-1.
To study acute myelogenous leukemia 1 (AML1) transcription factor, ETO protein, and t(8;21) AML chimeric AML1/ ETO protein in normal hematopoiesis and in leukemia, we raised rabbit antisera to a bacterially expressed polypeptide containing amino acid residues 1 to 220 of ETO and to synthetic peptides extending from residues 528 to 548 of ETO and 32 to 50 of AML1.
Association of MTG8 (ETO/CDR), a leukemia-related protein, with serine/threonine protein kinases and heat shock protein HSP90 in human hematopoietic cell lines.
The hMRP8-AML1-ETO-transgenic mice provide an excellent model that can be used to isolate additional genetic events and to further understand the molecular pathogenesis of AML1-ETO-related leukemia.
However, induction of cooperating mutations resulted in the development of an acute myeloid disease that mimicked many of the features of human AML1-ETO-expressing leukemia.
In summary, AMLI-ETO-expressing animals recapitulate many (and perhaps all) of the developmental abnormalities seen in human patients with the t(8;21) translocation, although the animals do not develop leukemia or disseminated disease in peripheral tissues like the liver or spleen.
Using parallel reverse transcriptase-PCR and real-time PCR (Taqman) screening, we find that the common leukemia fusion genes, TEL-AML1 or AML1-ETO, are present in cord bloods at a frequency that is 100-fold greater than the risk of the corresponding leukemia.
Uncommon chromosome changes may lead to the identification of leukemogenetic factors associated with t(8;21) since the AML1/RUNX1-ETO fusion gene resulting from the translocation is thought to be unable alone to induce leukemia.
Therefore, siRNAs are promising tools for a functional analysis of AML1/MTG8 and may be used in a molecularly defined therapeutic approach for t(8;21)-positive leukemia.
Despite numerous studies on the function of AML1-ETO, the precise mechanism by which the fusion protein is involved in leukemia development is still not fully understood.
This model should provide a useful platform to analyze the effect of AML1/ETO on hematopoiesis and its potential cooperation with other mutations in the pathogenesis of leukemia.
Experimental data have shown that AML1-ETO is not sufficient to induce leukemia by itself, but has to collaborate with other genetic alterations for leukemic transformation.
Leukemogenesis involves multiple genetic changes and, as suggested by murine experiments and other findings in humans, AML1-ETO expression may not be sufficient for full blown leukemia.
The model is supported by experimental data indicating that AML1-ETO and FLT3 length mutation (FLT3-LM), 2 of the most frequent genetic alterations in AML, are both insufficient on their own to cause leukemia in animal models.
The fusion gene produces a chimeric transcription factor that suppresses the expression of AML1-target genes via the MTG8 part of the chimeric protein, which is thought to be the primary cause of leukemia.