C-MYC amplification in a case of progression from MDS to AML (M2)

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C-MYC Amplification in a Case of Progression from MDS to AML (M2)

Cytogenetic abnormalities frequently found in myelodysplastic syndromes (MDS) include 5 q - , - 7 , and +8 [1]. While 5 q - per se is considered a favorable prognostic index, abnormalities involving chromosome 7 and trisomy 8 indicate an unfavorable prognosis and evolution to AML [2, 3]. N-ras point mutation is found in 9% to 40% of MDS cases [4] and, although not associated with a specific subtype, has been shown to be present in higher frequencies in acute transformation [5]. The presence of trisomy 8 in cases of evolution suggests that oncogenes mapped at this chromosome can participate in the leukemogenic process. One candidate is the c-MYC proto-oncogene. This oncogene has been proved important in several neoplastic transformations, presenting a high degree of amplification. Here we describe a patient with MDS (RAEB) and trisomy 8 who progressed to acute myeloid leukemia (AML) after 9 months. This patient showed a threefold amplification of c-MYC before

progressing to acute leukemia. As trisomy 8 was present in only 60% of the cells, much of this amplification must be occurring intrachromosomally. A 60-year-old white man presented in March, 1993 with a 6-month history of weakness, weight loss, and sleepiness. Physical examination disclosed hepatomegaly and paleness. On admission the patient's hemoglobin was 8.4 g/L, leukocyte count 2 × 109/L, and platelet count 59 x 109/L. Bone marrow aspirate was hypercellular with dysplasia of three lineages (ca. 5% of blasts), presenting a high content of iron and the presence of ringed sideroblasts. A cytogenetic study of bone marrow cells was done at this time according to Seabright [6]. Chromosomes were arranged according to the International System of Human Cytogenetics Nomenclature [7]. Two clones were found, 46,XY (23 ceils) and 47,XY,+8 (55 cells). A diagnosis of refractory anemia with excess of blasts (RAEB) was made. The patient progressed rapidly with several infections

Figure I C-MYC amplification analysis. A) Quantitative gel analysis, 5 p~g and 10 p.g of DNA digested with EcoR1, control DNA [1), patient DNA (2). B) Southern blot hybridization with a c-MYC-labelled probe, control DNA (1) and patient DNA (2). C) Densitometric analysis of hybridized bands showing a 3 × amplification of the c-MYC gene.

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Cancer Genet Cytogenet 86:183--184 (1996) © Elsevier Science Inc., 1996 655 Avenue of the Americas, N~w York, NY 10010

0165-4608/96/$15.00 SSDI o165-4608(95)o0191-Q

184 a n d received periodic transfusions. Six months later the platelet count was 20 × 109/L, leukocyte count 1.3 × 109/L, and the bone marrow aspirate s h o w e d an increase in myeloid lineages with prevalence for promyelocytes. At this time, the patient presented 30% of blasts in the bone marrow and persistence of ringed sideroblasts characterizing the evolution to AML (M2). Cytogenetic analysis disclosed a karyotypic evolution with the acquisition of two n e w clones: 47,XY,+dup(1)(q21q32),+8(eight cells) and 47,XY, der(8)t(1;8)(q21;p12) (three ceils). The patient received low doses of aracytin but d i e d from sepsis. N-ras p o i n t mutation and c-MYC amplification were tested at diagnosis. N-ras p o i n t mutation for codon 12 was a n a l y z e d by ASO (allele specific oligonucleotide) hybridization after PCR amplification using the N-ras codon 12 a m p l i m e r set (Clontech). The results s h o w e d the presence of one w i l d type allele (glycine) and one allele m u t a t e d to asparagine (GGT-~GAT). Amplification of c-MYC was tested by quantitative Southern blot. A n amplification level of 3 times was obtained in a densitometric analysis of Southern-blot bands, an amplification exceeding that expected from the existence of 60% of trisomic cells for chromosome 8 (Figure 1). Several oncogenes have been suggested to participate in the establishment and evolution of MDS. Although trisomy 8 is c o m m o n l y associated with evolution to AML, data proving the i n v o l v e m e n t of c-MYC in this process have never been produced. Here we s h o w e d that amplification of c-MYC can occur i n d e p e n d e n t l y of the presence of trisomy 8 and even before the cells are transformed to a leukemic clone. This result suggests that in this case c-MYC a m p l i f i c a t i o n m a y be a step in the e v o l u t i o n from MDS to AML.

T. de Souza Fernandez et al. TERESA DE SOUZA FERNANDEZ MARIA LUIZA MACEDO SILVA JAMISON DE SOUZA MARIA TEREZA M. DE PAULA ELIANA ABDELHAY Biophysics Institute Carlos Chagas Filho, Federal University of Rio de Janeiro, National Institute of Cancer, Rio de Janeiro, Hematology Institute Arthur Siqueira de Cavalcanti, Rio de Janeiro, Brazil.

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