Expression of L-myc and N-myc proto-oncogenes in human leukemias and
leukemia cell lines
H Hirvonen, V Hukkanen, TT Salmi, TP Makela, TT Pelliniemi, S Knuutila and R Alitalo
Department of Medical Biochemistry, University of Turku, Finland.
The myc proto-oncogenes encode nuclear phosphoproteins, which are believed
to participate in the control of cell proliferation and differentiation.
Deregulated expression of c-myc has been implicated in several human
hematopoietic malignancies. We have studied the expression and mRNA
processing of human L-myc, N-myc, and c-myc genes in a panel of human
leukemias, leukemia cell lines, and normal hematopoietic cells. L-myc mRNA
was expressed in three acute myeloid leukemias (AML) studied and in several
myeloid leukemia cell lines. Only low expression levels were observed in
adult bone marrow and in fetal spleen and thymus. The K562 and Dami
leukemia cell lines showed a unique pattern of L-myc mRNA processing, with
approximately 40% of L- myc mRNA lacking exon III and intron I. N-myc was
expressed in five of six AML cases studied, in one of nine acute
lymphocytic leukemia (ALL) cases, and in several leukemia cell lines, while
c-myc mRNA was detected in all leukemias and leukemia cell lines studied.
Coexpression of all three myc genes was observed in Dami and MOLT-4 cell
lines and in two AMLs, and either L-myc or N-myc was coexpressed with c-myc
in several other cases. These results show that in addition to c-myc, the
L-myc and N-myc genes are expressed in some human leukemias and leukemia
cell lines, and suggest a lack of mutually exclusive cross- regulation of
the myc genes in human leukemia cells.
Volume 78,
Issue 11,
pp. 3012-3020,
12/01/1991
Copyright © 1991 by The American Society of Hematology
