The delta isoform of Protein Kinase C (PKC-delta) is widely expressed in many normal tissues, including epidermal keratinocytes, and has a critical role in UV-induced apoptosis. However, PKC-delta is frequently lost in chemically or UV-induced mouse skin tumors, as well as in human cutaneous squamous cell carcinomas (SCC). Furthermore, re-expression of PKC-delta in human SCC lines is sufficient to induce apoptosis and suppress tumorigenicity, making PKC-delta a potential tumor suppressor gene for SCCs. The objective of this dissertation is to investigate the mechanism of PKC-delta loss in human SCCs.
To determine the mechanism of PKC-delta loss in human SCCs, we used Laser Capture Microdissection to isolate cells for RNA and DNA analysis from 3 normal epidermises and 14 human SCCs with low PKC-delta protein. Using this more selective approach, we found the tumor suppressor PKC-delta is lost at the mRNA level in human SCCs, and that the PKC-delta gene is rarely deleted suggesting that the mechanism of down-regulation of PKC-delta in SCCs is likely to be primarily at the level of gene transcription. To further explore the mechanism of PKC-delta down-regulation, we studied Ras-transformed immortalized human keratinocytes (HaCaT-Ras), which have selective down-regulation of the PKC-delta isoform at both protein and mRNA levels. Ras significantly repressed human PKC-delta promoter activity in HaCaT cells (85% reduction, p<0.05). Mutagenesis and ChIP studies of the PKC-delta promoter revealed that Ras activation represses PKC-delta promoter activity by activation of nuclear factor kappa B (NF-kB) and recruitment of repressive NF-kB subunits (p50 and c-Rel).
We also found that Fyn tyrosine kinase activation was necessary and sufficient for NF-kB activation and PKC-delta repression. In addition, Fyn was over-expressed in human SCCs and HaCaT-Ras cells. Furthermore, activation of PI3K/AKT pathway was necessary and sufficient for Ras-induced up-regulation of Fyn expression in HaCaT cells. Thus, a Ras-PI3K-Fyn-NF-kB pathway leads to PKC-delta repression in human keratinocytes. Our results have implications for the development of therapeutic strategies abrogating this signaling pathway to trigger the re-expression of pro-apoptotic PKC-delta to induce apoptosis in SCCs.
","abstract_html":"<p>The delta isoform of Protein Kinase C (PKC-delta) is widely expressed in many normal tissues, including epidermal keratinocytes, and has a critical role in UV-induced apoptosis. However, PKC-delta is frequently lost in chemically or UV-induced mouse skin tumors, as well as in human cutaneous squamous cell carcinomas (SCC). Furthermore, re-expression of PKC-delta in human SCC lines is sufficient to induce apoptosis and suppress tumorigenicity, making PKC-delta a potential tumor suppressor gene for SCCs. The objective of this dissertation is to investigate the mechanism of PKC-delta loss in human SCCs.</p><p>To determine the mechanism of PKC-delta loss in human SCCs, we used Laser Capture Microdissection to isolate cells for RNA and DNA analysis from 3 normal epidermises and 14 human SCCs with low PKC-delta protein. Using this more selective approach, we found the tumor suppressor PKC-delta is lost at the mRNA level in human SCCs, and that the PKC-delta gene is rarely deleted suggesting that the mechanism of down-regulation of PKC-delta in SCCs is likely to be primarily at the level of gene transcription. To further explore the mechanism of PKC-delta down-regulation, we studied Ras-transformed immortalized human keratinocytes (HaCaT-Ras), which have selective down-regulation of the PKC-delta isoform at both protein and mRNA levels. Ras significantly repressed human PKC-delta promoter activity in HaCaT cells (85% reduction, p<0.05). Mutagenesis and ChIP studies of the PKC-delta promoter revealed that Ras activation represses PKC-delta promoter activity by activation of nuclear factor kappa B (NF-kB) and recruitment of repressive NF-kB subunits (p50 and c-Rel).</p><p>We also found that Fyn tyrosine kinase activation was necessary and sufficient for NF-kB activation and PKC-delta repression. In addition, Fyn was over-expressed in human SCCs and HaCaT-Ras cells. Furthermore, activation of PI3K/AKT pathway was necessary and sufficient for Ras-induced up-regulation of Fyn expression in HaCaT cells. Thus, a Ras-PI3K-Fyn-NF-kB pathway leads to PKC-delta repression in human keratinocytes. Our results have implications for the development of therapeutic strategies abrogating this signaling pathway to trigger the re-expression of pro-apoptotic PKC-delta to induce apoptosis in SCCs.</p>","abstract_has_math":false,"creators":["Yadav, Vipin"],"institution":null,"degree_name":"Doctor of Philosophy (PhD)","degree_level":"Dissertation","degree_discipline":"Molecular Biology","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-01-01T08:00:00Z","date_published":"2011-01-01T08:00:00Z","updated_at":"2026-07-24T02:55:08Z","subjects":["fyn","nuclear factor kappaB","pkc delta","ras","skin cancer","tumor suppressor","Molecular Biology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://ecommons.luc.edu/luc_diss/183","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Yadav, Vipin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2016-03-31T17:08:46Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Molecular Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["fyn","nuclear factor kappaB","pkc delta","ras","skin cancer","tumor suppressor","Molecular Biology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://ecommons.luc.edu/luc_diss/183"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The delta isoform of Protein Kinase C (PKC-delta) is widely expressed in many normal tissues, including epidermal keratinocytes, and has a critical role in UV-induced apoptosis. However, PKC-delta is frequently lost in chemically or UV-induced mouse skin tumors, as well as in human cutaneous squamous cell carcinomas (SCC). Furthermore, re-expression of PKC-delta in human SCC lines is sufficient to induce apoptosis and suppress tumorigenicity, making PKC-delta a potential tumor suppressor gene for SCCs. The objective of this dissertation is to investigate the mechanism of PKC-delta loss in human SCCs.
To determine the mechanism of PKC-delta loss in human SCCs, we used Laser Capture Microdissection to isolate cells for RNA and DNA analysis from 3 normal epidermises and 14 human SCCs with low PKC-delta protein. Using this more selective approach, we found the tumor suppressor PKC-delta is lost at the mRNA level in human SCCs, and that the PKC-delta gene is rarely deleted suggesting that the mechanism of down-regulation of PKC-delta in SCCs is likely to be primarily at the level of gene transcription. To further explore the mechanism of PKC-delta down-regulation, we studied Ras-transformed immortalized human keratinocytes (HaCaT-Ras), which have selective down-regulation of the PKC-delta isoform at both protein and mRNA levels. Ras significantly repressed human PKC-delta promoter activity in HaCaT cells (85% reduction, p<0.05). Mutagenesis and ChIP studies of the PKC-delta promoter revealed that Ras activation represses PKC-delta promoter activity by activation of nuclear factor kappa B (NF-kB) and recruitment of repressive NF-kB subunits (p50 and c-Rel).
We also found that Fyn tyrosine kinase activation was necessary and sufficient for NF-kB activation and PKC-delta repression. In addition, Fyn was over-expressed in human SCCs and HaCaT-Ras cells. Furthermore, activation of PI3K/AKT pathway was necessary and sufficient for Ras-induced up-regulation of Fyn expression in HaCaT cells. Thus, a Ras-PI3K-Fyn-NF-kB pathway leads to PKC-delta repression in human keratinocytes. Our results have implications for the development of therapeutic strategies abrogating this signaling pathway to trigger the re-expression of pro-apoptotic PKC-delta to induce apoptosis in SCCs.
"]},{"key":"dc:title","label":"Title","values":["Repression of Protein Kinase C Delta in Human Squamous Cell Carcinomas by Ras, Fyn and NF-Kappa B Signaling"]}]}],"canonical_facts":{"dc:creator":["Yadav, Vipin"],"dc:date.available":["2016-03-31T17:08:46Z"],"dc:description.abstract":["The delta isoform of Protein Kinase C (PKC-delta) is widely expressed in many normal tissues, including epidermal keratinocytes, and has a critical role in UV-induced apoptosis. However, PKC-delta is frequently lost in chemically or UV-induced mouse skin tumors, as well as in human cutaneous squamous cell carcinomas (SCC). Furthermore, re-expression of PKC-delta in human SCC lines is sufficient to induce apoptosis and suppress tumorigenicity, making PKC-delta a potential tumor suppressor gene for SCCs. The objective of this dissertation is to investigate the mechanism of PKC-delta loss in human SCCs.
To determine the mechanism of PKC-delta loss in human SCCs, we used Laser Capture Microdissection to isolate cells for RNA and DNA analysis from 3 normal epidermises and 14 human SCCs with low PKC-delta protein. Using this more selective approach, we found the tumor suppressor PKC-delta is lost at the mRNA level in human SCCs, and that the PKC-delta gene is rarely deleted suggesting that the mechanism of down-regulation of PKC-delta in SCCs is likely to be primarily at the level of gene transcription. To further explore the mechanism of PKC-delta down-regulation, we studied Ras-transformed immortalized human keratinocytes (HaCaT-Ras), which have selective down-regulation of the PKC-delta isoform at both protein and mRNA levels. Ras significantly repressed human PKC-delta promoter activity in HaCaT cells (85% reduction, p<0.05). Mutagenesis and ChIP studies of the PKC-delta promoter revealed that Ras activation represses PKC-delta promoter activity by activation of nuclear factor kappa B (NF-kB) and recruitment of repressive NF-kB subunits (p50 and c-Rel).
We also found that Fyn tyrosine kinase activation was necessary and sufficient for NF-kB activation and PKC-delta repression. In addition, Fyn was over-expressed in human SCCs and HaCaT-Ras cells. Furthermore, activation of PI3K/AKT pathway was necessary and sufficient for Ras-induced up-regulation of Fyn expression in HaCaT cells. Thus, a Ras-PI3K-Fyn-NF-kB pathway leads to PKC-delta repression in human keratinocytes. Our results have implications for the development of therapeutic strategies abrogating this signaling pathway to trigger the re-expression of pro-apoptotic PKC-delta to induce apoptosis in SCCs.
"],"dc:identifier":["https://ecommons.luc.edu/luc_diss/183"],"dc:subject":["fyn","nuclear factor kappaB","pkc delta","ras","skin cancer","tumor suppressor","Molecular Biology"],"dc:title":["Repression of Protein Kinase C Delta in Human Squamous Cell Carcinomas by Ras, Fyn and NF-Kappa B Signaling"],"thesis:degree_discipline":["Molecular Biology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T02:55:08Z"}