Elucidation of the Mechanisms of Resistance and Sensitivity to Histone Deacetylase Inhibitor, PXD101, in Diffuse Large B-Cell Lymphoma (DLBCL)

Persistent Link:
http://hdl.handle.net/10150/301692
Title:
Elucidation of the Mechanisms of Resistance and Sensitivity to Histone Deacetylase Inhibitor, PXD101, in Diffuse Large B-Cell Lymphoma (DLBCL)
Author:
Tula Sanchez, Ana A.
Issue Date:
2013
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:
Although curable in the majority of cases, Diffuse Large B-cell Lymphoma (DLBCL), the most prevalent Non-Hodgkin Lymphoma (NHL) throughout the world, is still fatal for 30-40% patients. This patient population could benefit from the addition of new drugs to the current DLBCL chemotherapy regimen. Histone deacetylase inhibitors (HDIs) are a promising group of drugs for the treatment of hematological malignancies. In the current study we tested the HDI PXD101 in a panel of the two most common DLBCL subtypes, GCB (germinal center) and ABC (activated B-cell like), ABC being the least curable subtype. Cell viability assays showed that PXD101 induces antiproliferative effects at submicromolar concentrations in DLBCL cell lines regardless of DLBCL subtype. Flow cytometry demonstrated that upon PXD101 treatment two GCB cell lines (DB and OCILY19) undergo G2M cell cycle arrest followed by apoptosis, while two GCB (SUDHL4 and SUDHL8) and one ABC (U2932) cell line undergo G1 arrest with little apoptosis. Further experiments demonstrated that upon PXD101 removal G1-arresting cells recover their normal proliferative state, while in G2M-arresting cells only 8h exposure to PXD101 is sufficient to induce considerable apoptosis. We classified as PXD101-resistant cell lines that re-enter the cell cycle after drug removal, and PXD101-sensitive cell lines that commit to apoptosis after short periods of drug exposure. Kinase assays established that upon PXD101 treatment G1 phase cyclin dependent kinase 2 (CDK2)-cyclin E complex activity significantly decreases in resistant but not in sensitive cells lines. Furthermore, pull-down assays revealed that CDK inhibitors (CDKIs) p21 and/or p27 in resistant, but not sensitive cell lines persistently bind the CDK2-cyclin E complex throughout PXD101 treatment, thereby explaining why resistant lines stop at the G1 phase. CDKIs induction by PXD101 was p53-independent. This is the first time that an in vitro model of sensitivity and resistance to HDIs in DLBCL is established. We have also performed preliminary genomic and proteomic analysis in DLBCL cell lines treated with PXD101. We anticipate that further analysis of the genomic response and the functional impact of protein acetylation induced by HDIs will offer additional insight into mechanisms of sensitivity and resistance to HDIs in DLBCL.
Type:
text; Electronic Dissertation
Keywords:
HDACs; PXD101; Pharmacology & Toxicology; DLBCL
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Pharmacology & Toxicology
Degree Grantor:
University of Arizona
Advisor:
Smith, Catharine L.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleElucidation of the Mechanisms of Resistance and Sensitivity to Histone Deacetylase Inhibitor, PXD101, in Diffuse Large B-Cell Lymphoma (DLBCL)en_US
dc.creatorTula Sanchez, Ana A.en_US
dc.contributor.authorTula Sanchez, Ana A.en_US
dc.date.issued2013-
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.abstractAlthough curable in the majority of cases, Diffuse Large B-cell Lymphoma (DLBCL), the most prevalent Non-Hodgkin Lymphoma (NHL) throughout the world, is still fatal for 30-40% patients. This patient population could benefit from the addition of new drugs to the current DLBCL chemotherapy regimen. Histone deacetylase inhibitors (HDIs) are a promising group of drugs for the treatment of hematological malignancies. In the current study we tested the HDI PXD101 in a panel of the two most common DLBCL subtypes, GCB (germinal center) and ABC (activated B-cell like), ABC being the least curable subtype. Cell viability assays showed that PXD101 induces antiproliferative effects at submicromolar concentrations in DLBCL cell lines regardless of DLBCL subtype. Flow cytometry demonstrated that upon PXD101 treatment two GCB cell lines (DB and OCILY19) undergo G2M cell cycle arrest followed by apoptosis, while two GCB (SUDHL4 and SUDHL8) and one ABC (U2932) cell line undergo G1 arrest with little apoptosis. Further experiments demonstrated that upon PXD101 removal G1-arresting cells recover their normal proliferative state, while in G2M-arresting cells only 8h exposure to PXD101 is sufficient to induce considerable apoptosis. We classified as PXD101-resistant cell lines that re-enter the cell cycle after drug removal, and PXD101-sensitive cell lines that commit to apoptosis after short periods of drug exposure. Kinase assays established that upon PXD101 treatment G1 phase cyclin dependent kinase 2 (CDK2)-cyclin E complex activity significantly decreases in resistant but not in sensitive cells lines. Furthermore, pull-down assays revealed that CDK inhibitors (CDKIs) p21 and/or p27 in resistant, but not sensitive cell lines persistently bind the CDK2-cyclin E complex throughout PXD101 treatment, thereby explaining why resistant lines stop at the G1 phase. CDKIs induction by PXD101 was p53-independent. This is the first time that an in vitro model of sensitivity and resistance to HDIs in DLBCL is established. We have also performed preliminary genomic and proteomic analysis in DLBCL cell lines treated with PXD101. We anticipate that further analysis of the genomic response and the functional impact of protein acetylation induced by HDIs will offer additional insight into mechanisms of sensitivity and resistance to HDIs in DLBCL.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectHDACsen_US
dc.subjectPXD101en_US
dc.subjectPharmacology & Toxicologyen_US
dc.subjectDLBCLen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePharmacology & Toxicologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorSmith, Catharine L.en_US
dc.contributor.committeememberLau, Serrine S.en_US
dc.contributor.committeememberVaillancourt, Richard R.en_US
dc.contributor.committeememberFutscher, Bernard W.en_US
dc.contributor.committeememberZhang, Donna D.en_US
dc.contributor.committeememberSmith, Catharine L.en_US
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