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  • 1
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 12_Supplement ( 2022-06-15), p. 4096-4096
    Abstract: Ubiquitination is a metabolic process in eukaryotic cells that modifies proteins with ubiquitin leading to protein degradation via the ubiquitin-proteosome pathway. Cellular levels of ubiquitin are driven by the expression of RPS27A, UBA52, UBB and UBC. In cancer, the dysregulation of ubiquitination can affect various aspects of tumor progression including cell cycle regulation and gene expression. Ubiquitin B (UBB) gene has been shown to be over-expressed in some tumor types, including NSCLC and cervical cancer, and under-expressed in other tumors, in particularly a subset of ovarian cancers. A role for ubiquitin C (UBC) in cancer has not been well established but UBC has been described as a biomarker in renal cancer and CLL. In recent studies, repression of UBB in ovarian cancer cells was associated with sensitivity to UBC knockdown and demonstrated a synthetic lethal relationship. Since both UBB and UBC show substantial sequence homology, we explored the possibility of developing dual targeting siRNA that would silence both UBB and UBC. We identified unique individual siRNA sequences that efficiently silenced both UBB and UBC and led to rapid cytotoxicity in several cancer cell lines including the colon cancer cell line HCT-116, the breast cancer cell line SK-BR3, and the prostate cancer cell line 22Rv1. Treatment with either UBB-specific or UBC-specific siRNA did not show the same lethal phenotype. Dose response assays using the dual targeting siRNA designated U21 indicated EC50 for cytotoxicity between 50–500 pM in several cancer lines. Treatment of cancer cell lines with U21 leads to rapid apoptosis and cell death. Chemical modifications to pharmacologically stabilize the U21 siRNA sequence did not change its activity. The efficient cytotoxic activity of the U21 siRNA sequence has been integrated into our SeekR™ platform to create aptamer-siRNA chimeras for targeted delivery of the lethal U21 payload to specific cancer cell types. Citation Format: David O. Azorsa, David W. Lee, Marvin O'Ketch, Nathalie A. Azorsa, Ioanna Papacharalampous, Lizette A. Castaño, Jeffrey A. Kiefer, Spyro Mousses. Development of novel anticancer RNA therapeutics with dual-targeting siRNA that silences ubiquitin family members [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4096.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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  • 2
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 83, No. 7_Supplement ( 2023-04-04), p. 4417-4417
    Abstract: T-cells in the tumor microenvironment can often become exhausted and dysfunctional due to chronic and prolonged exposure to antigen. The resulting condition of T cell exhaustion represents an important mechanism of clinical resistance to immune checkpoint blockade. The transcription factor NR4A1 is known to be upregulated in tumor-specific T-cells and is a mediator of T cell dysfunction including driving exhaustion during chronic antigen stimulation of T-cells. Pro-oncogenic activities of NR4A1 have been observed in various solid tumors, including colorectal and breast cancers, and co-expression of NR4A1 with known immune checkpoint markers such as PD-L1 and B7 family members has also been observed in various cancer cell lines. These findings have identified NR4A1 as an important target for overcoming resistance to cancer immunotherapy. We hypothesize that targeted silencing of the NR4A1 and other immunomodulatory genes can reverse T-cell exhaustion and expand the clinical benefit of immune checkpoint blockade in solid tumors resistant to immune therapy. To reverse T-cell exhaustion with a targeted approach, we developed T cell targeting SeekRsTM, which are chimeric RNA therapeutics containing dual-flanking aptamer binders connected by a double-stranded bridge containing siRNA silencers that can target multiple immunomodulatory genes. First-generation aptamer-siRNA chimeras designed with a CTLA-4 targeting aptamer containing a STAT3 siRNA demonstrated effectiveness in silencing its target. Modifications to the structure included the addition of chemically modified nucleotides to improve serum stability. Additionally, dimerization of the structure to form a SeekR dimer molecule greatly improved internalization and target silencing compared to the monomeric chimera. Newly developed SeekRs targeting T cells and designed to silence NR4A1 have effectively downregulated NR4A1 in model cell lines and activated T cells. These results demonstrate that dual targeting SeekRs can be used to specifically deliver siRNA to T cells for targeted silencing that can reverse exhaustion and potentially overcome resistance to cancer immunotherapy in the clinic. Citation Format: Marvin O'Ketch, Jeffrey A. Kiefer, Dnyanesh Rasale, Warren S. Weiner, Lizette A. Castaño, Nathalie A. Azorsa, David W. Lee, Kerry M. Barnhart, Spyro Mousses, David O. Azorsa. Activity of novel RNA therapeutics to overcome resistance to immune checkpoint blockade. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4417.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2017
    In:  Cancer Research Vol. 77, No. 13_Supplement ( 2017-07-01), p. 3338-3338
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 77, No. 13_Supplement ( 2017-07-01), p. 3338-3338
    Abstract: Ewing sarcoma is the second most common cancer of bone and soft tissue arising in children and young adults. Although the survival rate has improved for patients treated for localized disease, the survival rate for patients with metastatic tumor remains lower than 30%. In order to identify novel therapeutic targets and to better understand the genes involved in growth and survival of Ewing sarcoma, we employed a functional genomics approach based on siRNA screening. Four Ewing sarcoma cell lines, TC-32, TC-71, SK-ES-1 and RD-ES, were transfected with a library of siRNA targeting 287 cancer-associated genes. The resulting siRNA screening data for each cell line were normalized and statistical cut-offs were determined. The results indicated that siRNAs targeting Fibroblast Growth Factor Receptor 4, FGFR4 were among the most effective in reducing cell viability in all four of the Ewing sarcoma cell lines. Validation of the siRNA screens showed that siRNAs to FGFR4, reduced viability much greater that those to FGFR1, FGFR2, or FGFR3. Furthermore, siRNA targeting FGFR4 were able to induce caspase 3 activity. FGFR4 protein is expressed on Ewing sarcoma cells as determined by western blot analysis, although expression levels were lower compared to FGFR4 expression on rhabdomyosarcoma cells. Targeting FGFR activity in Ewing sarcoma cells using a pan-FGFR inhibitors PD-173074 and BGJ-398 demonstrated that Ewing sarcoma cells were sensitive to FGFR inhibition. Furthermore, treatment of Ewing sarcoma cells with the selective FGFR4 inhibitor BLU9931 resulted in growth inhibition and decreased ERK signaling. These results indicate that FGFR4 may play an important role in growth and survival of Ewing sarcoma and could serve as a potential therapeutic target for this disease. Citation Format: Justin J. Montoya, Daniel H. Wai, David W. Lee, Peter A. Azorsa, Oliver B. Pepper, Robert J. Arceci, David O. Azorsa. A role for FGFR4 in growth and survival of Ewing sarcoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3338. doi:10.1158/1538-7445.AM2017-3338
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2017
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  • 4
    In: BMC Genomics, Springer Science and Business Media LLC, Vol. 11, No. 1 ( 2010-12)
    Abstract: Neurofibrillary tangles (NFT), a cardinal neuropathological feature of Alzheimer's disease (AD) that is highly correlated with synaptic loss and dementia severity, appear to be partly attributable to increased phosphorylation of the microtubule stabilizing protein tau at certain AD-related residues. Identifying the kinases involved in the pathologic phosphorylation of tau may provide targets at which to aim new AD-modifying treatments. Results We report results from a screen of 572 kinases in the human genome for effects on tau hyperphosphorylation using a loss of function, high-throughput RNAi approach. We confirm effects of three kinases from this screen, the eukaryotic translation initiation factor 2 α kinase 2 (EIF2AK2), the dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A), and the A-kinase anchor protein 13 (AKAP13) on tau phosphorylation at the 12E8 epitope (serine 262/serine 356). We provide evidence that EIF2AK2 effects may result from effects on tau protein expression, whereas DYRK1A and AKAP13 are likely more specifically involved in tau phosphorylation pathways. Conclusions These findings identify novel kinases that phosphorylate tau protein and provide a valuable reference data set describing the kinases involved in phosphorylating tau at an AD-relevant epitope.
    Type of Medium: Online Resource
    ISSN: 1471-2164
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2010
    detail.hit.zdb_id: 2041499-7
    SSG: 12
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  • 5
    In: BMC Cancer, Springer Science and Business Media LLC, Vol. 19, No. 1 ( 2019-12)
    Abstract: Acute Myeloid Leukemia (AML) is a malignancy of myeloid precursor cells that arise from genomic alterations in the expression of key growth regulatory genes causing cells to assume an undifferentiated state and continue to proliferate. Recent efforts have focused on developing therapies that target specific protein products of aberrantly expressed genes. However, many of the identified proteins are difficult to target and thought to be “undrugable” because of structural challenges, protein overexpression, or mutations that confer resistance to therapy. A novel technology that circumvents some of these issues is the use of small molecules that stabilize secondary DNA structures present in the promoters of many potential oncogenes and modulate their transcription. Methods This study characterizes the in vitro activity of the G-quadruplex-stabilizing small molecule GQC-05 in AML cells. The effect of GQC-05 on three AML cell lines was analyzed using viability and apoptosis assays. GQC-05 has been shown to down-regulate MYC through G-quadruplex stabilization in Burkitt’s lymphoma cell lines. MYC expression was evaluated through qPCR and immunoblotting in the three AML cell lines following the treatment of GQC-05. In order to identify other therapeutic agents that potentiate the activity of GQC-05, combination drug screening was performed. The drug combinations were validated using in vitro cytotoxicity assays and compared to other commonly used chemotherapeutic agents. Results GQC-05 treatment of KG-1a, CMK and TF-1 cells decreased cell viability and resulted in increased DNA damage and apoptosis. Additionally, treatment of KG-1a, CMK and TF-1 with GQC-05 resulted in decreased expression of MYC mRNA and protein, with a more pronounced effect in KG-1a cells. Combination drug screening identified the Bcl-2/Bcl-X L inhibitor Navitoclax as a compound that potentiated GQC-05 activity. Co-treatment with GQC-05 and Navitoclax showed a synergistic decrease in cell viability of AML cells as determined by Chou-Talalay analysis, and induced more DNA damage, apoptosis, and rapid cytotoxicity. The cytotoxicity induced by GQC-05 and Navitoclax was more potent than that of Navitoclax combined with either cytarabine or doxorubicin. Conclusion These results suggest that the G-quadruplex stabilizing small molecule GQC-05 induces down regulated MYC expression and DNA damage in AML cells. Treatment with both GQC-05 with a Bcl-2/Bcl-X L inhibitor Navitoclax results in increased cytotoxic activity, which is more pronounced than Navitoclax or GQC-05 alone, and more significant than Navitoclax in combination with cytarabine and doxorubicin that are currently being used clinically.
    Type of Medium: Online Resource
    ISSN: 1471-2407
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2041352-X
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  • 6
    In: Pediatric Blood & Cancer, Wiley, Vol. 65, No. 9 ( 2018-09)
    Abstract: Patients with Langerhans cell histiocytosis (LCH) harbor BRAF V600E and activating mutations of MAP2K1/MEK1 in 50% and 25% of cases, respectively. We evaluated a patient with treatment‐refractory LCH for mutations in the RAS‐RAF‐MEK‐ERK pathway and identified a novel mutation in the MAP2K1 gene resulting in a p.L98_K104  〉  Q deletion and predicted to be auto‐activating. During treatment with the MEK inhibitor trametinib, the patient's disease showed significant progression. In vitro characterization of the MAP2K1 p.L98_K104  〉  Q deletion confirmed its effect on cellular activation of the ERK pathway and drug resistance.
    Type of Medium: Online Resource
    ISSN: 1545-5009 , 1545-5017
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2130978-4
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  • 7
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 76, No. 5_Supplement ( 2016-03-01), p. B24-B24
    Abstract: Cancer is primarily a disease characterized by aberrant gene expression that is manifested by the overexpression of key genes that support tumor development and maintenance. In many instances, oncogenic drivers are frequently ‘undruggable’ because of structural challenges, the inability to effectively inhibit high concentrations of overexpressed proteins, and the development of drug resistance mutations. An alternative therapeutic approach is to directly inhibit gene transcription by targeting unique secondary DNA structures, called G-quadruplexes, that are associated with subsets of promoters. Our laboratory investigated the activity of a class of compounds termed G-quadruplex Interacting Drugs (GQIDs) that are able to shut down the expression of specific genes used by tumor cells for growth and survival. We tested the activity of two GQIDs GQC-05 and GSA-1103 on cell growth of a panel of eight pediatric and eight adult AML cell lines. Drug dose response analysis showed IC50 values ranging from approximately 10 nM to 1 µM for GQC-05 and from 40 nM to 2 µM for GSA-1103. The AML cell lines had different sensitivities to each GQID indicating a different mechanism of action for each compound. Three AML cell lines that were highly resistant to cytarabine were among the more sensitive to GQC-05. Four cell lines sensitive to GQC-05 had high expression of either c-myc and/or bcl-2, both of which are potential targets of these two GQIDs. Furthermore, treatment of cells with the GQC-05 decreased expression of c-myc and bcl-2. These studies will help define a novel approach of repressing key drivers of leukemia by targeting selective promoter structures. Validation of such an approach for AML will have important implications for testing this therapeutic approach to other childhood cancers in order to improve the length and quality of survival. Citation Format: Apurvi Patel, Justin J. Montoya, Megan Turnidge, Marya Sabir, Daniel H. Wai, David W. Lee, Vijay Gokhale, Eiman Aleem, Laurence J. Hurley, Robert J. Arceci, David O. Azorsa. Targeting promoter regions of oncogenic drivers in pediatric AML cells using G-quadruplex Interacting Drugs (GQIDs). [abstract]. In: Proceedings of the AACR Special Conference on Advances in Pediatric Cancer Research: From Mechanisms and Models to Treatment and Survivorship; 2015 Nov 9-12; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(5 Suppl):Abstract nr B24.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2016
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  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 2005
    In:  Drug Discovery Today: Technologies Vol. 2, No. 2 ( 2005-6), p. 141-147
    In: Drug Discovery Today: Technologies, Elsevier BV, Vol. 2, No. 2 ( 2005-6), p. 141-147
    Type of Medium: Online Resource
    ISSN: 1740-6749
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2005
    detail.hit.zdb_id: 2165475-X
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  • 9
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2022
    In:  Cancer Research Vol. 82, No. 12_Supplement ( 2022-06-15), p. 4239-4239
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 82, No. 12_Supplement ( 2022-06-15), p. 4239-4239
    Abstract: T-cell exhaustion describes the dysfunctional state of effector T cells in the tumor microenvironment that results from chronic and prolonged exposure to antigen. It also represents an important mechanism of clinical resistance to immune checkpoint blockade. Recently, the transcription factor NR4A1 has been shown to be upregulated in tumor-specific T cells and plays a role in driving exhaustion during chronic antigen stimulation of T cells. Pro-oncogenic activities of NR4A1 have long been observed in various solid tumors including colorectal and breast cancers, and co-expression of NR4A1 with known immune checkpoint markers such as PD-L1 have also been observed in various cancer cell lines. These findings have identified NR4A1 as an important target for overcoming resistance to cancer immunotherapy. We hypothesize that multi-targeting to simultaneously block PD-1 signaling and silence NR4A1 gene expression can reverse T-cell exhaustion and expand the clinical benefit of PD-1 blockade in immune therapy resistant solid tumors. Using our SeekR™ RNA therapeutics platform, we combined aptamer binders to PD-1 with siRNA against NR4A1, andNR4A1 and evaluated their ability to reverse T-cell exhaustion and re-activate T-cell based anticancer immunity in solid tumors. Specifically, we created SeekR™ therapeutic RNA molecules with dual flanking RNA aptamers binders to PD-1 and other checkpoint inhibitors, connected by a double stranded bridge that encodes for siRNA silencers that target multiple immunomodulatory genes, such as NR4A1. The novel anti-PD-1 RNA aptamer component serve to: A) direct and deliver the SeekR™ RNA oligo therapeutics to exhausted T-cells that express PD-1 receptors; and B) internalize the siRNA component into the T-cells. The siRNA components of the SeekR™ serve to silence NR4A1 which lead to reversal of the cytotoxic T-cell exhausted phenotype following chronic in-vitro stimulation. These results demonstrate that dual targeting of PD-1 and NR4A1 has the potential to reverse T-cell exhaustion and the potential to overcome cancer immunotherapy resistance in the clinic. Citation Format: Marvin O'ketch, Victoria A. Love, Jeffrey A. Kiefer, David W. Lee, Lizette A. Castaño, Spyro Mousses, David O. Azorsa. Development of multi-targeting immunomodulatory SeekR RNA therapeutics to overcome resistance to PD-1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4239.
    Type of Medium: Online Resource
    ISSN: 1538-7445
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2022
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    detail.hit.zdb_id: 410466-3
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  • 10
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 79, No. 13_Supplement ( 2019-07-01), p. 2967-2967
    Abstract: Acute Myeloid Leukemia (AML) is a malignancy of myeloid precursor cells that can occur when genomic changes alter expression of key genes, causing cells to resume an undifferentiated state and proliferate. Ongoing efforts have focused on developing therapies that specifically target the protein products of aberrantly expressed genes. However, many of the identified proteins are difficult to target because of structural challenges, protein overexpression, or mutations that confer resistance to therapy. A type of therapy that circumvents these issues is the use of small molecules that stabilize DNA secondary structures called G-quadruplexes, which are present in the promoters of many potential oncogenes, and have regulatory roles in their transcription. This study analyzes the activity of G-quadruplex stabilizing small molecule GQC-05 that has been shown to down-regulate MYC, which is commonly misregulated in AML. Treatment of MYC-expressing AML cell lines KG-1a, CMK and TF-1 with GQC-05 resulted in decreased expression of MYC mRNA and protein, with the effect more pronounced in KG-1a cells. GQC-05 treatment of the AML cells decreased cell viability, while increasing apoptosis and DNA damage. Combinational drug screening was performed to identify compounds that potentiated the anti-proliferative effects of GQC-05. Results from the screen identified the BCL-2 inhibitor Navitoclax as a compound that potentiated GQC-05 activity. Co-treatment with GQC-05 and Navitoclax showed synergistic effect on cell viability of AML cells as determined by Chou-Talalay analysis. Furthermore, co-treatment with Navitoclax did not affect the downregulation of MYC by GQC-05, but did increase apoptosis and DNA damage leading to rapid cytotoxicity. These results indicate that the G-quadruplex stabilizing small molecule GQC-05 may function more as a DNA damaging agent in AML cells and that combining GQC-05 with a Bcl-2/Bcl-XLinhibitor such as Navitoclax can result in increased cytotoxic activity. Citation Format: Justin J. Montoya, Megan A. Turnidge, Daniel H. Wai, David W. Lee, Apruvi Patel, Vijay Gokhale, Laurence J. Hurley, David O. Azorsa. Activity of G-quadruplex stabilizing small molecule that downregulates MYC and synergizes with Navitoclax in acute myeloid leukemia cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2967.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2019
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    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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