Peter C. Nowell

Molecular Basis of Human B Cell Neoplasia

Consistent karyotypic changes have been observed in several human malignancies of the hematopoietic system (1–4). Many of these somatic changes involve reciprocal chromosomal translocations.

Dexamethasone inhibition of interleukin 1 beta production by human monocytes. Posttranscriptional mechanisms.

Dexamethasone is known to have an inhibitory effect on IL-1 production. To determine the mechanism(s) of this inhibition, adherent human blood monocytes were stimulated with Escherichia coli lipopolysaccharide (LPS) (10 micrograms/ml) in the presence of dexamethasone. Nuclear transcription run-off assays showed that LPS induced IL-1 beta gene transcription two- to fourfold and that this induction was unaffected by dexamethasone exposure (10(-5) M). The lack of dexamethasones transcriptional effects was further supported by the absence of any significant change in IL-1 beta mRNA accumulation between LPS-stimulated monocytes exposed or unexposed to dexamethasone, as determined by Northern blot analysis. Posttranscriptionally, dexamethasone was found to have multiple effects: slight prolongation of IL-1 beta mRNA half-life, moderate inhibition of translation of the IL-1 beta precursor, and profound inhibition of the release of IL-1 beta into the extracellular fluid. The data indicate that IL-1 beta is first translated as the 33,000-D pro-IL-1 beta protein, the predominant intracellular form, and the processed to a 17,500-D IL-1 beta protein before or during extracellular transport. The major inhibitory effects of dexamethasone appear to be directed at the translational and posttranslational steps involved in these events.

Characteristics of Cultured Human Melanocytes Isolated from Different Stages of Tumor Progression

Normal melanocytes and melanocytes of normal nevi, primary melanoma in the radial (RGP) and vertical (VGP) growth phases, and metastatic melanoma exhibited and maintained phenotypic differences when grown in tissue culture or in experimental animals. Only metastatic and VGP primary melanoma cells were tumorigenic in athymic nude mice and had nonrandom chromosomal abnormalities involving chromosomes 1, 6, and 7. The colony-forming efficiency in soft agar was also highest in these two cell types. A cell line of RGP primary melanoma had characteristics of both benign and malignant cells: nevus-like morphology; nontumorigenicity in nude mice; but karyotypic abnormality of chromosome 6. It also had a ganglioside pattern similar to that of normal melanocytes but not melanomas, i.e., a high GM3 ganglioside content compared to the amounts of GM2, GD2, and GD3 gangliosides. Binding of monoclonal antibodies secreted by hybridomas generated by immunization of mice with VGP primary and metastatic melanoma was highest with cells and supernatants of cultures from advanced melanoma and least with nevus cells. There was no binding to normal melanocytes except with the monoclonal antibodies specific for nerve growth factor receptor or 9-O-acetyl-GD3 ganglioside. On the other hand, monoclonal anti-nevus antibodies bound to melanocytes, nevus cells, and RGP primary melanoma cells but not to VGP primary or metastatic melanoma cells. Cultured human melanocytic cells appear to be a unique model for the study of tumor progression.

Cytogenetics of human malignant melanoma and premalignant lesions

Chromosome studies were done on direct preparations, early passage cultures, and/or cell lines derived from melanocytic lesions of 17 patients. There were 5 nevi (3 dysplastic); 1 early primary melanoma (radial growth phase); 1 advanced primary melanoma (vertical growth phase) with multiple metastases; and 10 metastatic lesions. The 5 nevi had normal karyotypes, while each of the tumors had a predominantly abnormal karyotype. The early melanoma was pseudodiploid, including a 6p;22 translocation. Ten of the 11 advanced melanomas had one or more aberrations involving chromosome #1, with 9 having deletions or translocations of lp that involved the proximal segment 1p12----1p22 9 times in 8 lesions. Six advanced tumors had additional material involving 7q, including extra #7s (4 cases) and 7q+ (2 cases). Nine melanomas, including the early tumor, had alterations in chromosome #6. Three had additional copies of 6p (as iso6p or t6p); the others showed no consistent pattern. In one advanced tumor, the primary lesion and 5 metastases (removed seriatim over an 18-month period) had nearly identical karyotypes, indicating the clonal nature of the neoplasm. The nonrandom cytogenetic changes suggest that genes important in melanoma carcinogenesis are located on the proximal portion of 1p, on 7q, and on chromosome #6. More data on early lesions are needed to identify the relation of these various cytogenetic changes to the different stages of malignant melanoma development.

Expression of the receptor for epidermal growth factor correlates with increased dosage of chromosome 7 in malignant melanoma

Epidermal growth factor (EGF) receptor is expressed selectively by human melanoma cells which show the presence of an extra copy of chromosome 7. None of the cells of benign pigmented lesions (nevi) or radial growth phase (nonmetastatic) primary melanoma expressed EGF receptor and none of these cells showed an extra copy of chromosome 7. The results indicate that a single extra dose of a gene (for EGF receptor) may provide a selective advantage to cells in the late stages of tumorigenesis.

Karyotypic evolution in human malignant melanoma

Chromosome studies were performed on direct preparations, early passage cultures, and cell lines derived from melanocytic lesions of 37 patients. There were six congenital or common acquired nevi, six dysplastic nevi, one early primary melanoma (radial growth phase), three complex melanomas (RGP with foci of vertical growth phase), six advanced primary melanomas (VGP), and 26 metastases. The karyotype was normal in the six common nevi. A chromosomally abnormal clone with a single karyotypic alteration was found in two dysplastic nevi. All melanomas had clones with multiple cytogenetic changes. Nonrandom abnormalities involving translocations or deletions in the short arm of chromosome #1, either arm of chromosome #6, and/or extra copies of the short arm of chromosome #7 were present in all melanomas. These were not obviously associated with a particular stage of disease, except that the only nonrandom alteration in the early (RGP) melanoma involved chromosome #6. In four cases, cytogenetic data were available on both a primary melanoma and its metastases. In each instance there were common alterations (demonstrating the clonality of the disease), as well as additional changes in the metastases. Our findings indicate that demonstrable somatic genetic abnormalities increase in severity with clinical progression of melanocytic disease, but additional data are required to establish the significance of specific karyotypic changes (and the involved genes) in the clinical evolution of these disorders.

Oncogenic potential of bcl-2 demonstrated by gene transfer

Follicular lymphoma is the most common human B-cell malignancy in the United States and Western Europe1. Most of the tumours contain t(14;18) chromosome translocations involving the human bcl-2 gene2–5. Translocation of bcl-2 sequences from chromosome 18 into the transcriptionally active immunoglobulin locus at chromosome band 14q32 in B cells deregulates bcl-2 gene expression, resulting in the accumulation of high levels of bcl-2 messenger3. Human bcl-2 transcripts generate two proteins, p26 bcl-2-α and p22 bcl-2-β, by virtue of alternative splice-site selection2. Both proteins have in common their first 196 NH2-terminal amino acids but share little similarity with other sequences in a data bank2,4. Although the biological and biochemical functions of bcl-2 are unknown, recent subcellular localization studies indi-cate that p26 bcl-2-α associates with cellular membranes, con-sistent with a stretch of hydrophobic amino acids in its carboxy terminus1,2,6. The bcl-2 gene may represent a novel oncogene having no known retroviral counterpart. Here we demonstrate the oncogenic potential of bcl-2 through a gene transfer approach.

Chromosome studies in preleukemic states. IV. Myeloproliferative versus cytopenic disorders

The prognostic value of marrow chromosome studies was examined in 112 “preleukemic” patients followed for at least one year or until death. Based on recent definitions, 49 patients were classified as myeloproliferative disorders (MPD) (polycythemia vera, myelofibrosis, undifferentiated myeloproliferative disorder, essential thrombocythemia), and 58 as cytopenic states (refractory anemia, pancytopenia). In each group, approximately one‐third had a chromosomally‐abnormal clone. For MPD, this had little predictive value, but in the cytopenias, 77% with a cytogenetic abnormality developed leukemia versus 39% without. Twelve cytopenic patients had multiple alterations involving more than 2 chromosomes and 11 died within 6 months, 9 with leukemia. Such patients may warrant consideration for aggressive chemotherapy before the appearance of clinical leukemia. Banding studies did not reveal any specific chromosome abnormalities consistently associated with these various preleukemic disorders, or with progression to leukemia, but nonrandom alterations were noted involving chromosomes 1, 5, 7‐9, and 20 in the MPD group, and chromosomes 6 and 16 in the cytopenic patients. Correlation of these data with other reports indicates that certain cytogenetic abnormalities involving specific segments of the human genome confer a selective growth advantage on hemic clones which may present clinically as either preleukemia or leukemia. Cancer 42:2254–2261, 1978.

Discovery of the Philadelphia chromosome: a personal perspective

Almost 50 years ago, David Hungerford and I noticed an abnormally small chromosome in cells from patients with chronic myelogenous leukemia (CML). This article is a personal perspective of the events leading to the discovery of this chromosome, which became known as the Philadelphia chromosome. As technology advanced over subsequent decades, the translocation resulting in the Philadelphia chromosome has been identified, its role in the development of CML has been confirmed, and a therapy directed against the abnormal protein it produces has shown promising results in the treatment of patients with CML.

Analysis of the androgen response of 23 patients with agnogenic myeloid metaplasia: The value of chromosomal studies in predicting response and survival

The responses of 23 patients with agnogenic myeloid metaplasia (AMM) to androgen therapy were studied. Various clinical and laboratory parameters were analyzed for their value in determining response to therapy and length of survival. Fifty‐seven percent of patients responded, as determined by a sustained increase in hematocrit within three months of therapy which thus eliminated the need for transfusions. Chromosome study of the abnormal hemic population was the best predictor of response: 92% of patients with normal chromosomes responded, while 78% of patients with chromosomal abnormalities did not. Responders had a mean survival time of five and a half years from the time of diagnosis as compared with two years for the nonresponders. The degree of thrombocytopenia, suppression of the ferrokinetic, and lack of activity in axial skeleton on bone marrow scans indicated severely compromised hemopoiesis in the nonresponders. The results suggest that in some patients with AMM, more extensive cytogenetic alterations in the abnormal hematopoietic cells result in an inability to respond to androgen therapy and that the chromosome study is the test most accurate for predicting the outcome of therapy.