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dc.contributor.authorPan, Quintin
dc.contributor.advisorSimpson, Robert U.
dc.date.accessioned2016-08-30T17:56:04Z
dc.date.available2016-08-30T17:56:04Z
dc.date.issued1999
dc.identifier.urihttp://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:9938509
dc.identifier.urihttps://hdl.handle.net/2027.42/131972
dc.description.abstractThe hormone, 1,25-dihydroxyvitamin D<sub>3</sub> [1,25-(OH)<sub>2</sub>D<sub> 3</sub>], has been established as an important regulator of cellular proliferation and differentiation in various target tissues. HL-60 promyelocytic leukemia cells are terminally differentiated into mature monocytes/macrophages by 1,25-(OH)<sub> 2</sub>D<sub>3</sub>. Promotion of HL-60 cell differentiation involves programmed changes in the transcription of numerous genes, including protein kinase Cbeta (PKCbeta) and c-<italic>myc</italic> protooncogene. 1,25-(OH)<sub>2</sub>D<sub> 3</sub> maximally increased PKCbeta levels and promoted HL-60 cell differentiation within 48--72 hours of continuous treatment. When PKCbeta levels and cell differentiation were assayed at 72 hours, treatment with 1,25-(OH)<sub> 2</sub>D<sub>3</sub> for the initial 6 hours significantly increased PKCbeta levels but had little effect on cell differentiation. Therefore, continuous treatment with 1,25-(OH)<sub>2</sub>D<sub>3</sub> is required for differentiation. Cell differentiation promoted by ionomycin, a calcium ionophore and activator of PKCbeta, in 1,25-(OH)<sub>2</sub>D<sub>3</sub> pretreated cells was similar to differentiation promoted by continuous 1,25-(OH)<sub>2</sub>D<sub>3</sub> treatment. The data suggest that the hormone must activate PKCbeta as well as increase its expression to promote cell differentiation fully. Additionally, the results reveal that 1,25-(OH)<sub>2</sub>D<sub>3</sub> has increased sufficient <italic>de novo</italic> synthesis of PKCbeta after 6 hours to promote differentiation fully if activation cofactors, calcium and diacylglycerol, are increased. Next, the physiological relevance of three putative regulatory c-<italic>myc</italic> intron element protein binding sites (MIE1, MIE2, and MIE3) was determined. 1,25-(OH)<sub>2</sub>D<sub>3 </sub> enhanced nuclear proteins to bind to MIE1, MIE2, and MIE3. With a wildtype c-<italic>myc</italic> promoter construct containing MIE1, MIE2, and MIE3, 1,25-(OH)<sub>2</sub>D<sub>3</sub> reduced CAT reporter expression. The ability of 1,25-(OH)<sub>2</sub>D<sub>3</sub> to inhibit CAT activity was significantly decreased with a MIE1 deletion construct and completely abolished with a MIE1, MIE2, and MIE3 deletion construct. Chelerythrine chloride, a PKC activity inhibitor, and a PKCbeta antisense oligonucleotide, prevented the binding of nuclear proteins to MIE1, MIE2, and MIE3. The predominant MIE1 binding protein was purified, sequenced, and found to be HOXB4. A HOXB4 antisense oligonucleotide was able to significantly inhibit the induction of HOXB4 levels by 1,25-(OH)<sub>2</sub>D<sub>3</sub>. Moreover, this HOXB4 antisense was able to block 1,25-(OH)<sub>2</sub>D<sub>3</sub> from decreasing c-<italic> myc</italic> levels. These results shows that HOXB4, a nuclear phosphoprotein, is expressed and activated by 1,25-(OH)<sub>2</sub>D<sub>3</sub> leading to a block in c-<italic>myc</italic> transcription and HL-60 cell differentiation. In summary, this dissertation brings a better understanding of the mechanisms involved in terminal differentiation of a cancer cell and may provide the basis for novel therapeutic approaches to combat cancer.
dc.format.extent122 p.
dc.languageEnglish
dc.language.isoEN
dc.subjectBeta
dc.subjectC-myc
dc.subjectCell Differentiation
dc.subjectDihydroxyvitamin D3-1,25
dc.subjectExpression
dc.subjectHl-60
dc.subjectHoxb4
dc.subjectPkc
dc.subjectProtein Kinase C
dc.subjectRegulation
dc.subjectRole
dc.title1,25-dihydroxyvitamin D(3) regulation of c-myc expression and HL-60 cell differentiation: A role for PKC-beta and HOXB4.
dc.typeThesis
dc.description.thesisdegreenamePh.D.
dc.description.thesisdegreedisciplineBiological Sciences
dc.description.thesisdegreedisciplineHealth and Environmental Sciences
dc.description.thesisdegreedisciplineMolecular biology
dc.description.thesisdegreedisciplineOncology
dc.description.thesisdegreedisciplinePharmacology
dc.description.thesisdegreegrantorUniversity of Michigan, Horace H. Rackham School of Graduate Studies
dc.description.bitstreamurlhttp://deepblue.lib.umich.edu/bitstream/2027.42/131972/2/9938509.pdf
dc.owningcollnameDissertations and Theses (Ph.D. and Master's)


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