Microscopic visualization of melanocyte/melanoma melanotropin receptors.

Persistent Link:
http://hdl.handle.net/10150/186401
Title:
Microscopic visualization of melanocyte/melanoma melanotropin receptors.
Author:
Jiang, Jinwen.
Issue Date:
1993
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The objectives of this research were to determine whether melanotropin receptors are characteristic (constant) membrane markers of melanocytes, and, more importantly human melanoma cells. Methodologies were developed to visualize these receptors by light, scanning electron (SEM) and fluorescence microscopy. Multiple copies (up to a hundred) of [Nle⁴, D-Phe⁷] α-MSH, a superpotent analog of α-melanocyte stimulating hormone (α-MSH), were conjugated to macromolecular carriers, either latex beads (microspheres and macrospheres) or another inert substrate, polyvinyl alcohol (PVA). Multiple copies (up to a hundred) of a fluorophore were also attached to the PVA. Incubation in the presence of the macromolecular conjugates of the analog resulted in binding of human normal epidermal melanocytes and melanoma cells (but not other cells) to both small and large beads and to the fluorescent conjugate. Binding of the microspheres or the fluorescent conjugate to the cells exhibited a unique cluster pattern (capping) suggesting a receptor internalization related phenomenon. Only a single aggregate of beads was present on each cell suggesting a focal site of endocytosis. Most importantly, every cell of every melanoma cell line possessed receptors as visualized by fluorescence microscopy. Since the cells were not synchronized, binding apparently took place during all phases of the cell cycle. Therefore, receptor expression is not cell-cycle dependent. Specificity of binding of the macromolecular conjugates was demonstrated by several studies: (1) binding of melanocytes/melanoma cells to the conjugates was specific since it could be blocked by prior incubation of the cells in the presence of the unconjugated hormone analog, (2) the macromolecular substrates (latex beads, PVA) lacking bound ligand did not bind to the melanoma cells or melanocytes, (3) another peptide ligand (e.g., substance-P) attached to the substrates failed to bind to the cells, and (4) cells of nonmelanocyte origin (e.g., mammary cancer cells, lung cancer cells, fibroblasts) did not bind to the macromolecular conjugates. Thus, cell specific melanotropin receptors appear to be characteristic cell surface markers of epidermal melanocytes and melanoma cells. Fluorescent melanotropin conjugates should be useful in determining whether all human melanoma (primary and metastatic) tumors possess such receptors. These receptors may provide targets for melanotropic peptides for the identification, localization, and chemotherapy of melanoma.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic.; Microbiology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Anatomy; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Hadley, Mac E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleMicroscopic visualization of melanocyte/melanoma melanotropin receptors.en_US
dc.creatorJiang, Jinwen.en_US
dc.contributor.authorJiang, Jinwen.en_US
dc.date.issued1993en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe objectives of this research were to determine whether melanotropin receptors are characteristic (constant) membrane markers of melanocytes, and, more importantly human melanoma cells. Methodologies were developed to visualize these receptors by light, scanning electron (SEM) and fluorescence microscopy. Multiple copies (up to a hundred) of [Nle⁴, D-Phe⁷] α-MSH, a superpotent analog of α-melanocyte stimulating hormone (α-MSH), were conjugated to macromolecular carriers, either latex beads (microspheres and macrospheres) or another inert substrate, polyvinyl alcohol (PVA). Multiple copies (up to a hundred) of a fluorophore were also attached to the PVA. Incubation in the presence of the macromolecular conjugates of the analog resulted in binding of human normal epidermal melanocytes and melanoma cells (but not other cells) to both small and large beads and to the fluorescent conjugate. Binding of the microspheres or the fluorescent conjugate to the cells exhibited a unique cluster pattern (capping) suggesting a receptor internalization related phenomenon. Only a single aggregate of beads was present on each cell suggesting a focal site of endocytosis. Most importantly, every cell of every melanoma cell line possessed receptors as visualized by fluorescence microscopy. Since the cells were not synchronized, binding apparently took place during all phases of the cell cycle. Therefore, receptor expression is not cell-cycle dependent. Specificity of binding of the macromolecular conjugates was demonstrated by several studies: (1) binding of melanocytes/melanoma cells to the conjugates was specific since it could be blocked by prior incubation of the cells in the presence of the unconjugated hormone analog, (2) the macromolecular substrates (latex beads, PVA) lacking bound ligand did not bind to the melanoma cells or melanocytes, (3) another peptide ligand (e.g., substance-P) attached to the substrates failed to bind to the cells, and (4) cells of nonmelanocyte origin (e.g., mammary cancer cells, lung cancer cells, fibroblasts) did not bind to the macromolecular conjugates. Thus, cell specific melanotropin receptors appear to be characteristic cell surface markers of epidermal melanocytes and melanoma cells. Fluorescent melanotropin conjugates should be useful in determining whether all human melanoma (primary and metastatic) tumors possess such receptors. These receptors may provide targets for melanotropic peptides for the identification, localization, and chemotherapy of melanoma.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academic.en_US
dc.subjectMicrobiology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAnatomyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairHadley, Mac E.en_US
dc.contributor.committeememberBagnara, Joseph T.en_US
dc.contributor.committeememberBenson, Bryanten_US
dc.contributor.committeememberHendrix, Mary J. C.en_US
dc.contributor.committeememberBurd, Gail D.en_US
dc.identifier.proquest9408477en_US
dc.identifier.oclc720429684en_US
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