1992 — 1993 |
Hoffman, Barbara |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Gene Dissection of Myeloid Differentiation &Leukemias @ University of Pennsylvania |
1 |
1994 — 1996 |
Hoffman, Barbara |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Gene Dissection of Myeloid Differentiation and Leukemias
Blocks in differentiation appear to be a major step in tumor progression. The long term objectives of the research plan is to gain a better understanding of the molecular mechanisms that control terminal myeloid differentiation and growth arrest and how these processes can be blocked, thereby contributing to leukemogenesis. The M1 myeloid leukemia cell line, which proliferates autonomously and undergoes terminal differentiation, growth arrest and loss of leukemogenicity when treated with the physiological inducers IL-6 and leukemia inhibitory factor (LIF) is used. The research scheme is to genetically manipulate M1 cells to block induced differentiation, followed by analysis. The research plan encompasses: 1. Studies the role of c-myc suppression in myeloid differentiation; how continuous expression blocks differentiation growth arrest and exit from the cell cycle. Genes directly regulated by c-myc during myeloid growth and differentiation will be cloned using chimeric myc genes. Expression, sequence and functional analysis of the myc regulated genes will be done. The effects of continued expression of c-myc: on the regulation of expression of the cell cycle genes cdc2 and cyclin, the cell cycle regulated phosphorylation of the retinoblastoma protein and the loss of tumorigenicity will be determined. Finally, analyzing proteins in M and M1myc cells by 2-D gel electrophoresis should give an overall picture of how myc blocks the myeloid differentiation genetic program. 2. Studies on the role of c-myc in the regulation of myeloid differentiation prior to its suppression. Premature suppression of c-myc blocks induced differentiation, resulting in cell death. The role of sustained, early c-myc expression during differentiation and where the block in differentiation is will be determined. Premature suppression of c-myc may cause the cells to exit the cell cycle prematurely. Cell cycle analysis by flow cytometry, cyclin and cdc2 expression and RB protein phosphorylation will be analyzed. 3. Studies on c-myb in myeloid differentiation, growth arrest, and blocking differentiation. Continued expression of c-myb blocks M1 differentiation. That c-myb blocks differentiation by activating c-myc will be tested by antisense experiments. When differentiation is blocked will be determined, following the basic plan described for c-myc. 4. The role of Hox-2.4 in blocking terminal myeloid differentiation and growth arrest. The homeobox Hox-2.4 gene appears to impede IL-3 driven terminal myeloid differentiation. M1Hox-2.4 cells constitutively expressing Hox-2.4 will be generated to determine if Hox-2.4 blocks M1 myeloid differentiation, and if so, where the block is, as well as if the loss of tumorigenicity is blocked. Analysis will follow the same scheme as for c-myc and c- myb. In addition, Hox-2.4 genes activated/suppressed in uninduced M1 cells will be cloned and analyzed. Information from these studies should lead to an increased understanding of the regulation of differentiation and how perturbing normal controls can block differentiation and contribute to leukemogenesis, ultimately aiding in diagnosis, prognosis and eventual therapy.
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1 |
1999 — 2009 |
Hoffman, Barbara |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Negative Regulators of Myelopoiesis
The long term objective of the research program is to gain a better understanding of the molecular-genetic controls of myelopoiesis and leukemogenesis. An experimental approach to dissect the regulation of differentiation and how differentiation blocks can arise is to genetically manipulate myeloid cells, and to analyze these cells at the cellular, molecular and genetic level. It has been shown that, in addition to constitutive c-myc causing Interleukin-6 (IL-6) treated M1myc cells to arrest at an intermediate stage of differentation, a portion of the IL-6 treated proliferating population of cells undergoes apoptotic cell death. Similar observations were made for the nonleukemic 32D cell line and normal myeloid cells from bone marrow (BM). It is hypothesized that the effects of c-myc on hematopoietic development are mediated via c-myc target genes and genes induced by differentiation factors. The c-myc target gene cdc25A appears to mediate some effects of c-myc on differentiation, and the genes Gadd45, MyD116 and CR6, induced by myeloid differentiation factors, participate in the apoptotic response associated with the block in differentiation. This proposal intends to extend these novel findings, to decipher how these gene products participate in the myc-mediated effects on myeloid development, and to identify other players. Since c-myc is a member of a transcription factor network which regulates c-myc target genes, to understand how c-myc carries out its functions it is necessary to understand this network of interacting factors. The proposed studies will employ the M1 and 32D cell lines, as well as myeloid cells from BM. The specific aims of this proposal are: Aim I: Molecular-Genetic Dissection of c-myc-mediated block in differentiation and growth arrest: A role for the c-myc target gene cdc25A and other target genes. Aim II: Molecular-genetic Dissection of the Apoptotic Response Associated with the Myc- Mediated Block in Terminal Differentiation: A Role for MyD and Gadd Genes. Aim III: To ascertain the role of the network of c- myc interacting factors in regulating differentiation, growth arrest and apoptosis. These studies should reveal how perturbing c-myc, and, therefore, normal cell cycle controls, can block differentiation, alter cell survival, and promote leukemogenesis. These investigations should contribute to a greater understanding of the genetic events involved in the pathogenesis of different leukemias, ultimately aiding in diagnosis, prognosis and eventual therapy.
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1 |
2009 |
Hoffman, Barbara |
U2GActivity Code Description: In cooperation with other countries, international organizations, and other partners to conduct HIV/AIDS prevention, care and treatment of non-research activities in international countries most heavily affected by the HIV/AIDS epidemic. |
Pepfar Laboratory Training Project @ American Society For Clinical Pathology |
0.904 |