Retinoid receptor turnover mediated by sumoylation, ubiquitination and the valosin-containing protein is disrupted in glioblastoma

Abstract Resistance to therapeutic use of retinoids in glioma has been observed for over 20 years; however, the exact mechanism of resistance remains unknown. To understand retinoic acid resistance in glioma, we studied the turnover mechanism of retinoid receptor proteins in neural stem cells and glioma stem-like cells. Here, we show that in normal neural stem cells, proteasomal degradation of retinoid receptors involves sumoylation, ubiquitination and recognition by the valosin-containing protein (VCP/p97/Cdc48). We find that Sumo1 modification has a dual role to stabilize the retinoid receptor from unwanted degradation and signal additional modification via ubiquitination. Subsequently, the modified receptor binds to the VCP chaperone and both proteins are degraded by the proteasome. Additionally, we reveal that all trans retinoic acid (ATRA) induces VCP expression, creating a positive feedback loop that enhances degradation. In contrast, the pathway is impaired in the glioma stem-like cells resulting in the accumulation of sumoylated and high molecular weight forms of retinoid receptors that lack transcriptional activity and fail to be recognized by the proteasome. Moreover, modified receptor accumulation occurs before ATRA treatment; therefore, the transcritptional defect in glioma is due to a block in the proteasomal degradation pathway that occurs after the sumo modification step.

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Abstract 2900: Sumoylation of the retinoic acid receptor alpha protein represses transcriptional activity and contributes to retinoic acid resistance in glioma stem cells

10.1158/1538-7445.am2016-2900 ◽

2016 ◽

Author(s):

Virginia W. Rodriguez ◽

Rolanda Bailey ◽

Mark Gilbert

Keyword(s):

Stem Cells ◽

Retinoic Acid ◽

Transcriptional Activity ◽

Retinoic Acid Receptor ◽

Acid Resistance ◽

Glioma Stem Cells ◽

Retinoic Acid Receptor Alpha ◽

Acid Receptor ◽

Receptor Alpha ◽

Retinoic Acid Resistance

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Involvement of Retinoic Acid Receptor-α–Mediated Signaling Pathway in Induction of CD38 Cell-Surface Antigen

Blood ◽

10.1182/blood.v89.10.3607.3607_3607_3614 ◽

1997 ◽

Vol 89 (10) ◽

pp. 3607-3614 ◽

Cited By ~ 2

Author(s):

Kapil Mehta ◽

Teresa McQueen ◽

Taghi Manshouri ◽

Michael Andreeff ◽

Steven Collins ◽

...

Keyword(s):

Retinoic Acid ◽

Transgenic Mice ◽

Cell Line ◽

Leukemia Cell Line ◽

Single Chain ◽

Retinoid Receptor ◽

Induced Expression ◽

Retinoid Receptors ◽

Cd38 Expression ◽

Dominant Negative Mutation

Human leukocyte antigen CD38, a 45-kD single-chain, transmembrane glycoprotein, is a bifunctional ectoenzyme that participates in signal transduction pathways involved in the regulation of cell growth and differentiation. In this study, we demonstrate the nature of retinoid receptors involved in retinoic acid–induced expression of CD38 protein in the human myeloblastic leukemia cell line HL-60. We used a variant HL-60 cell line, HL-60R, in which retinoid receptor function has been abrogated by a trans-dominant negative mutation. We introduced the normal retinoic acid receptors (RAR)-α, -β, and -γ or retinoid X receptor (RXR)-α into HL-60R cells by retroviral vector-mediated gene transfer. Based on experiments using these cell lines and receptor-specific synthetic retinoids that preferentially bind to one of the RARs or RXRs, we conclude that RAR-α is involved in retinoid-induced CD38 expression in HL-60 cells. Further evidence included our demonstration that blocking of RAR-α with the antagonist Ro 41-5253 completely suppressed the retinoid-induced expression of CD38 mRNA transcript and the production of CD38 protein in HL-60 cells. Various tissues from transgenic mice that expressed an antisense construct of RAR-α lacked or produced very low levels of CD38. As expected, the tissues from transgenic mice contained 50% to 80% reduced levels of RAR-α. These results suggest that regulation of CD38 expression, both in vitro and in vivo, is under the direct control of RAR-α retinoid receptors.

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Constitutive Degradation of PML/RAR Through the Proteasome Pathway Mediates Retinoic Acid Resistance

Blood ◽

10.1182/blood.v93.5.1477 ◽

1999 ◽

Vol 93 (5) ◽

pp. 1477-1481 ◽

Cited By ~ 46

Author(s):

Mirco Fanelli ◽

Saverio Minucci ◽

Vania Gelmetti ◽

Clara Nervi ◽

Carlo Gambacorti-Passerini ◽

...

Keyword(s):

Retinoic Acid ◽

Proteasome Inhibitors ◽

Acid Resistance ◽

Parental Cell ◽

Parental Cell Line ◽

In Vitro Degradation ◽

Nb4 Cells ◽

Proteasome Pathway ◽

Retinoic Acid Resistance

Abstract PML/RAR is the leukemogenetic protein of acute promyelocytic leukemia (APL). Treatment with retinoic acid (RA) induces degradation of PML/RAR, differentiation of leukaemic blasts, and disease remission. However, RA resistance arises during RA treatment of APL patients. To investigate the phenomenon of RA resistance in APL, we generated RA-resistant sublines from APL-derived NB4 cells. The NB4.007/6 RA-resistant subline does not express the PML/RAR protein, although its mRNA is detectable at levels comparable to those of the parental cell line. In vitro degradation assays showed that the half-life of PML/RAR is less than 30 minutes in NB4.007/6 and longer than 3 hours in NB4. Treatment of NB4.007/6 cells with the proteasome inhibitors LLnL and lactacystin partially restored PML/RAR protein expression and resulted in a partial release of the RA-resistant phenotype. Similarly, forced expression of PML/RAR, but not RAR, into the NB4/007.6 cells restored sensitivity to RA treatment to levels comparable to those of the NB4 cells. These results indicate that constitutive degradation of PML/RAR protein may lead to RA resistance and that PML/RAR expression is crucial to convey RA sensitivity to APL cells.

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