Oncogenes: clues to carcinogenesis

Amplification and expression of the N-myc gene in neuroblastoma

Genomic configuration and expression of the N-myc gene was investigated by Southern and Northern blot analyses in 18 neuroblastomas of different clinical stages. We observed a 4-100-fold amplification of this oncogene in one of six stage III, two of four stage IV as well as one of five stage IVS tumours. Remarkably, an 80-fold N-myc amplification was demonstrated in a patient with stage IV neuroblastoma being in remission for more than 2 years; moreover, a 100-fold amplification could be detected in a stage IVS tumour from a newborn. These data are discussed in view of the recently postulated close association of N-myc amplification with rapid progression of neuroblastomas.

Karyotype and ultrastructure of a colony stimulating factor (CSF) producing cell line (5637) originated from a carcinoma of the human urinary bladder

The cell line 5637 which originated from a human urinary bladder carcinoma is known to produce GM-CSF and Multi-CSF ectopically. Determination of cell surface antigens defined by monoclonal antibodies was recently reported. Here we report on the ultrastructure and karyology of this CSF secreting cell line. At the ultrastructural level the monolayer in vitro culture and the solid tumors formed in nude mice showed all characteristics consistent with a well-differentiated transitional cell carcinoma (TCC). A subclone was found to grow in suspension and did not secrete any CSF activity. High resolution chromosome analysis revealed chromosomal abnormalities which agreed only in few particulars with nonrandom chromosomal aberrations usually found in TCC. Analysis of the cytogenetic results showed that nearly all structural abnormalities present are known to be associated with acute or chronic human leukemia. The possibility that the ectopic production of CSF in this cell line may be correlated to one or more of the described chromosomal aberrations is discussed.

Tumour karyotype may be important in the prognosis of human neuroblastoma

When comparing clinical and tumour cytogenetic data on 14 neuroblastoma patients in different stages of disease we found a high incidence of 1p abnormalities (12/12), homogeneously staining regions/double minutes (9/12) and 2p abnormalities (4/12) in 12 unresectable and metastatic tumours (clinical stages III and IV). In contrast, these features were absent in clinical stage II tumours (2/2) with good prognosis. The coincidence of 1p aberrations with poor outcome of disease will be discussed.

Height at diagnosis in acute lymphocytic leukaemia

The heights of children with acute lymphocytic leukaemia were compared with controls matched for age, sex, and period. In contrast to a previous report the subject patients were not taller than their matched controls.

(11; 14) translocation in three boys with acute lymphoblastic leukemia of T-cell immunophenotype

Three boys, 12, 15 and 5 years old are presented with acute lymphoblastic leukemia resp. Non-Hodgkin's lymphoma with leukemic transformation. Blast cells could be characterized as being of T-cell origin. Hand mirror variant was the predominant morphologic feature of the blast cells in two patients. Chromosome analysis of the leukemic blast cells revealed a pseudodiploid (modal chromosome number = 46) karyotype in two patients and a pseudotetraploid (modal chromosome number = 92) in one patient. A chromosome translocation (11; 14) with breakpoints at (p 13; q 13) (within the human T-cell receptor alpha chain locus!) was found in the leukemic cells of all three cases plus an additional t (7; 9) (q 22; p 13) in one patient.

Human leukemia K562 cells: relationship between hemin-mediated erythroid induction, cell proliferation and expression of c-abl and c-myc oncogenes

We have studied the expression of the c-myc and c-abl oncogenes in two human leukemic K562 cell lines which do express hemoglobin genes retaining a differential rate of cell proliferation. Our data indicate that in hemin-induced K562(S) cells the expression of c-abl oncogene decreases and appears to be related to a decrease in the proliferation capacity rather than to the activation of differentiated functions. The K562(hC) cell line, which produces large amounts of Hb Gower 1 retaining an efficient rate of cell proliferation, expresses indeed the c-abl oncogene at high level.