{"id":{"repo_id":"ttu","oai_identifier":"oai:ttu-ir.tdl.org:2346/14235"},"canonical_url":"https://search.dev.ndltd.org/etd/ttu/oai:ttu-ir.tdl.org:2346/14235","repository":{"repo_id":"ttu","name":"Texas Technology University","base_url":"https://ttu-ir.tdl.org/server/oai/request"},"display":{"title":"Insulin-mediated inhibition of tyrosinase activity and protein synthesis in melanoma cell cultures","abstract":"Insulin lowers basal levels of tyrosinase activity and inhibits the MSH-stimulated rise in tyrosinase in Cloudman S-91 mouse melanoma cell cultures. These cultures are very sensitive to insulin. A concentration of insulin as low as 5 x 10 M insulin produces optimum inhibition. At maximum inhibition, tyrosinase activity is reduced to approximately 50% of control levels. Insulin inhibits cellular proliferation in melanoma cells; however, inhibition of tyrosinase activity precedes this effect. Insulin also inhibits the (Bu)2 cAMP and theophylline stimulated rise in enzyme activity. This finding suggests that insulin exerts its effects at a site distal to cAMP production. Insulin, in fact, does not lower cAMP levels in melanoma cells, nor does it alter the MSH-stimulated rise of cAMP. The inhibitory effect of insulin on tyrosinase activity could not be mimicked by either (Bu)2 cGMP or 8-bromo-cGMP, suggesting that insulin does not exert its effects by altering cellular levels of this nucleotide. Insulin decreases the incorporation of [3H]-leucine into trichloracetic acid insoluble material by 50%, an inhibition which corresponds well with the observed level of reduction of tyrosinase activity. This finding suggests that the inhibition of tyrosinase activity may be caused by a general reduction in protein synthesis due to insulin treatment.","abstract_html":"Insulin lowers basal levels of tyrosinase activity and inhibits the MSH-stimulated rise in tyrosinase in Cloudman S-91 mouse melanoma cell cultures. These cultures are very sensitive to insulin. A concentration of insulin as low as 5 x 10 M insulin produces optimum inhibition. At maximum inhibition, tyrosinase activity is reduced to approximately 50% of control levels. Insulin inhibits cellular proliferation in melanoma cells; however, inhibition of tyrosinase activity precedes this effect. Insulin also inhibits the (Bu)2 cAMP and theophylline stimulated rise in enzyme activity. This finding suggests that insulin exerts its effects at a site distal to cAMP production. Insulin, in fact, does not lower cAMP levels in melanoma cells, nor does it alter the MSH-stimulated rise of cAMP. The inhibitory effect of insulin on tyrosinase activity could not be mimicked by either (Bu)2 cGMP or 8-bromo-cGMP, suggesting that insulin does not exert its effects by altering cellular levels of this nucleotide. Insulin decreases the incorporation of [3H]-leucine into trichloracetic acid insoluble material by 50%, an inhibition which corresponds well with the observed level of reduction of tyrosinase activity. This finding suggests that the inhibition of tyrosinase activity may be caused by a general reduction in protein synthesis due to insulin treatment.","abstract_has_math":false,"creators":["Ehlers, Susan Elizabeth"],"institution":"Texas Tech University","degree_name":"M.S.","degree_level":"Masters","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1984,"date_issued":"1984-05","date_published":"1984-05","updated_at":"2026-07-24T05:04:54Z","subjects":["Proteins -- Synthesis","Melanoma","Insulin","Phenol oxidase","Enzyme inhibitors","Rats -- Physiology"],"languages":["eng"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2346/14235","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Ehlers, Susan Elizabeth"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2011-02-18T20:35:28Z"]},{"key":"dc:date.issued","label":"Date","values":["1984-05"]},{"key":"dc:publisher","label":"Institution","values":["Texas Tech University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Texas Tech University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Proteins -- Synthesis","Melanoma","Insulin","Phenol oxidase","Enzyme inhibitors","Rats -- Physiology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["eng"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/2346/14235"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Insulin lowers basal levels of tyrosinase activity and inhibits the MSH-stimulated rise in tyrosinase in Cloudman S-91 mouse melanoma cell cultures. These cultures are very sensitive to insulin. A concentration of insulin as low as 5 x 10 M insulin produces optimum inhibition. At maximum inhibition, tyrosinase activity is reduced to approximately 50% of control levels. Insulin inhibits cellular proliferation in melanoma cells; however, inhibition of tyrosinase activity precedes this effect. Insulin also inhibits the (Bu)2 cAMP and theophylline stimulated rise in enzyme activity. This finding suggests that insulin exerts its effects at a site distal to cAMP production. Insulin, in fact, does not lower cAMP levels in melanoma cells, nor does it alter the MSH-stimulated rise of cAMP. The inhibitory effect of insulin on tyrosinase activity could not be mimicked by either (Bu)2 cGMP or 8-bromo-cGMP, suggesting that insulin does not exert its effects by altering cellular levels of this nucleotide. Insulin decreases the incorporation of [3H]-leucine into trichloracetic acid insoluble material by 50%, an inhibition which corresponds well with the observed level of reduction of tyrosinase activity. This finding suggests that the inhibition of tyrosinase activity may be caused by a general reduction in protein synthesis due to insulin treatment."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Insulin-mediated inhibition of tyrosinase activity and protein synthesis in melanoma cell cultures"]}]}],"canonical_facts":{"dc:creator":["Ehlers, Susan Elizabeth"],"dc:date.available":["2011-02-18T20:35:28Z"],"dc:date.issued":["1984-05"],"dc:description.abstract":["Insulin lowers basal levels of tyrosinase activity and inhibits the MSH-stimulated rise in tyrosinase in Cloudman S-91 mouse melanoma cell cultures. These cultures are very sensitive to insulin. A concentration of insulin as low as 5 x 10 M insulin produces optimum inhibition. At maximum inhibition, tyrosinase activity is reduced to approximately 50% of control levels. Insulin inhibits cellular proliferation in melanoma cells; however, inhibition of tyrosinase activity precedes this effect. Insulin also inhibits the (Bu)2 cAMP and theophylline stimulated rise in enzyme activity. This finding suggests that insulin exerts its effects at a site distal to cAMP production. Insulin, in fact, does not lower cAMP levels in melanoma cells, nor does it alter the MSH-stimulated rise of cAMP. The inhibitory effect of insulin on tyrosinase activity could not be mimicked by either (Bu)2 cGMP or 8-bromo-cGMP, suggesting that insulin does not exert its effects by altering cellular levels of this nucleotide. Insulin decreases the incorporation of [3H]-leucine into trichloracetic acid insoluble material by 50%, an inhibition which corresponds well with the observed level of reduction of tyrosinase activity. This finding suggests that the inhibition of tyrosinase activity may be caused by a general reduction in protein synthesis due to insulin treatment."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/2346/14235"],"dc:language.iso":["eng"],"dc:publisher":["Texas Tech University"],"dc:subject":["Proteins -- Synthesis","Melanoma","Insulin","Phenol oxidase","Enzyme inhibitors","Rats -- Physiology"],"dc:title":["Insulin-mediated inhibition of tyrosinase activity and protein synthesis in melanoma cell cultures"],"dc:type":["Thesis"],"thesis:degree_level":["Masters"],"thesis:degree_name":["M.S."],"thesis:institution_name":["Texas Tech University"]},"updated_at":"2026-07-24T05:04:54Z"}