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Alam SK, Wang L, Zhu Z, Hoeppner LH. IKKα promotes lung adenocarcinoma growth through ERK signaling activation via DARPP-32-mediated inhibition of PP1 activity. NPJ Precis Oncol 2023; 7:33. [PMID: 36966223 PMCID: PMC10039943 DOI: 10.1038/s41698-023-00370-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 03/08/2023] [Indexed: 03/27/2023] Open
Abstract
Non-small cell lung cancer (NSCLC) accounts for 80-85% cases of lung cancer cases. Diagnosis at advanced stages is common, after which therapy-refractory disease progression frequently occurs. Therefore, a better understanding of the molecular mechanisms that control NSCLC progression is necessary to develop new therapies. Overexpression of IκB kinase α (IKKα) in NSCLC correlates with poor patient survival. IKKα is an NF-κB-activating kinase that is important in cell survival and differentiation, but its regulation of oncogenic signaling is not well understood. We recently demonstrated that IKKα promotes NSCLC cell migration by physically interacting with dopamine- and cyclic AMP-regulated phosphoprotein, Mr 32000 (DARPP-32), and its truncated splice variant, t-DARPP. Here, we show that IKKα phosphorylates DARPP-32 at threonine 34, resulting in DARPP-32-mediated inhibition of protein phosphatase 1 (PP1), subsequent inhibition of PP1-mediated dephosphorylation of ERK, and activation of ERK signaling to promote lung oncogenesis. Correspondingly, IKKα ablation in human lung adenocarcinoma cells reduced their anchorage-independent growth in soft agar. Mice challenged with IKKα-ablated HCC827 cells exhibited less lung tumor growth than mice orthotopically administered control HCC827 cells. Our findings suggest that IKKα drives NSCLC growth through the activation of ERK signaling via DARPP-32-mediated inhibition of PP1 activity.
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Affiliation(s)
- Sk Kayum Alam
- The Hormel Institute, University of Minnesota, Austin, MN, USA.
| | - Li Wang
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Zhu Zhu
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Luke H Hoeppner
- The Hormel Institute, University of Minnesota, Austin, MN, USA.
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
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DARPP-32 promotes ERBB3-mediated resistance to molecular targeted therapy in EGFR-mutated lung adenocarcinoma. Oncogene 2022; 41:83-98. [PMID: 34675407 PMCID: PMC8529229 DOI: 10.1038/s41388-021-02028-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 09/03/2021] [Accepted: 09/17/2021] [Indexed: 12/11/2022]
Abstract
Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)-refractory lung adenocarcinoma (LUAD) progression is a major clinical problem. New approaches to predict and prevent acquired resistance to EGFR TKIs are urgently needed. Here, we show that dopamine and cyclic AMP-regulated phosphoprotein, Mr 32000 (DARPP-32) physically recruits ERBB3 (HER3) to EGFR to mediate switching from EGFR homodimers to EGFR:ERBB3 heterodimers to bypass EGFR TKI-mediated inhibition by potentiating ERBB3-dependent activation of oncogenic signaling. In paired LUAD patient-derived specimens before and after EGFR TKI-refractory disease progression, we reveal that DARPP-32 and kinase-activated EGFR and ERBB3 proteins are overexpressed upon acquired resistance. In mice, DARPP-32 ablation sensitizes gefitinib-resistant xenografts to EGFR TKIs, while DARPP-32 overexpression increases gefitinib-refractory LUAD progression in gefitinib-sensitive lung tumors. We introduce a DARPP-32-mediated, ERBB3-dependent mechanism the LUAD cells use to evade EGFR TKI-induced cell death, potentially paving the way for the development of therapies to better combat therapy-refractory LUAD progression.
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Wang L, Astone M, Alam SK, Zhu Z, Pei W, Frank DA, Burgess SM, Hoeppner LH. Suppressing STAT3 activity protects the endothelial barrier from VEGF-mediated vascular permeability. Dis Model Mech 2021; 14:272222. [PMID: 34542605 PMCID: PMC8592016 DOI: 10.1242/dmm.049029] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 09/10/2021] [Indexed: 12/27/2022] Open
Abstract
Vascular permeability triggered by inflammation or ischemia promotes edema, exacerbates disease progression and impairs tissue recovery. Vascular endothelial growth factor (VEGF) is a potent inducer of vascular permeability. VEGF plays an integral role in regulating vascular barrier function physiologically and in pathologies, including cancer, stroke, cardiovascular disease, retinal conditions and COVID-19-associated pulmonary edema, sepsis and acute lung injury. Understanding temporal molecular regulation of VEGF-induced vascular permeability will facilitate developing therapeutics to inhibit vascular permeability, while preserving tissue-restorative angiogenesis. Here, we demonstrate that VEGF signals through signal transducer and activator of transcription 3 (STAT3) to promote vascular permeability. We show that genetic STAT3 ablation reduces vascular permeability in STAT3-deficient endothelium of mice and VEGF-inducible zebrafish crossed with CRISPR/Cas9-generated Stat3 knockout zebrafish. Intercellular adhesion molecule 1 (ICAM-1) expression is transcriptionally regulated by STAT3, and VEGF-dependent STAT3 activation is regulated by JAK2. Pyrimethamine, an FDA-approved antimicrobial agent that inhibits STAT3-dependent transcription, substantially reduces VEGF-induced vascular permeability in zebrafish, mouse and human endothelium. Collectively, our findings suggest that VEGF/VEGFR-2/JAK2/STAT3 signaling regulates vascular barrier integrity, and inhibition of STAT3-dependent activity reduces VEGF-induced vascular permeability. This article has an associated First Person interview with the first author of the paper. Summary: Genetic STAT3 ablation in mice and VEGF-inducible zebrafish reveals that VEGF signals through STAT3 to promote vascular permeability. Pyrimethamine reduces VEGF-induced permeability in animal models.
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Affiliation(s)
- Li Wang
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Matteo Astone
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Sk Kayum Alam
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Zhu Zhu
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Wuhong Pei
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - David A Frank
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Shawn M Burgess
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20814, USA
| | - Luke H Hoeppner
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
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Wang L, Astone M, Alam SK, Zhu Z, Pei W, Frank DA, Burgess SM, Hoeppner LH. Suppressing STAT3 activity protects the endothelial barrier from VEGF-mediated vascular permeability. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 33140053 PMCID: PMC7605565 DOI: 10.1101/2020.10.27.358374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Vascular permeability triggered by inflammation or ischemia promotes edema, exacerbates disease progression, and impairs tissue recovery. Vascular endothelial growth factor (VEGF) is a potent inducer of vascular permeability. VEGF plays an integral role in regulating vascular barrier function physiologically and in pathologies, such as cancer, ischemic stroke, cardiovascular disease, retinal conditions, and COVID-19-associated pulmonary edema and sepsis, which often leads to acute lung injury, including acute respiratory distress syndrome. However, after initially stimulating permeability, VEGF subsequently mediates angiogenesis to repair damaged tissue. Consequently, understanding temporal molecular regulation of VEG-Finduced vascular permeability will facilitate developing therapeutics that achieve the delicate balance of inhibiting vascular permeability while preserving tissue repair. Here, we demonstrate that VEGF signals through signal transducer and activator of transcription 3 (STAT3) to promote vascular permeability. Specifically, we show that genetic STAT3 ablation reduces vascular permeability in STAT3-deficient endothelium of mice and VEGF-inducible zebrafish crossed with CRISPR/Cas9 generated genomic STAT3 knockout zebrafish. Importantly, STAT3 deficiency does not impair vascular development and function in vivo. We identify intercellular adhesion molecule 1 (ICAM-1) as a STAT3-dependent transcriptional regulator and show VEGF-dependent STAT3 activation is regulated by JAK2. Pyrimethamine, an FDA-approved antimicrobial agent that inhibits STAT3-dependent transcription, substantially reduces VEGF-induced vascular permeability in zebrafish, mouse, and human endothelium. Indeed, pharmacologically targeting STAT3 increases vascular barrier integrity using two additional compounds, atovaquone and C188-9. Collectively, our findings suggest that the VEGF, VEGFR-2, JAK2, and STAT3 signaling cascade regulates vascular barrier integrity, and inhibition of STAT3-dependent activity reduces VEGF-induced vascular permeability in vertebrate models.
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Affiliation(s)
- Li Wang
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Matteo Astone
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Sk Kayum Alam
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Zhu Zhu
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Wuhong Pei
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - David A Frank
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Shawn M Burgess
- Translational and Functional Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Luke H Hoeppner
- The Hormel Institute, University of Minnesota, Austin, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
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Alam SK, Wang L, Ren Y, Hernandez CE, Kosari F, Roden AC, Yang R, Hoeppner LH. ASCL1-regulated DARPP-32 and t-DARPP stimulate small cell lung cancer growth and neuroendocrine tumour cell proliferation. Br J Cancer 2020; 123:819-832. [PMID: 32499571 PMCID: PMC7463034 DOI: 10.1038/s41416-020-0923-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 04/21/2020] [Accepted: 05/13/2020] [Indexed: 01/09/2023] Open
Abstract
Background Small cell lung cancer (SCLC) is the most aggressive form of lung cancer, and new molecular insights are necessary for prognostic and therapeutic advances. Methods Dopamine and cAMP-regulated phosphoprotein, Mr 32000 (DARPP-32) and its N-terminally truncated splice variant, t-DARPP, were stably overexpressed or ablated in human DMS-53 and H1048 SCLC cells. Functional assays and immunoblotting were used to assess how DARPP-32 isoforms regulate SCLC cell growth, proliferation, and apoptosis. DARPP-32-modulated SCLC cells were orthotopically injected into the lungs of SCID mice to evaluate how DARPP-32 and t-DARPP regulate neuroendocrine tumour growth. Immunostaining for DARPP-32 proteins was performed in SCLC patient-derived specimens. Bioinformatics analysis and subsequent transcription assays were used to determine the mechanistic basis of DARPP-32-regulated SCLC growth. Results We demonstrate in mice that DARPP-32 and t-DARPP promote SCLC growth through increased Akt/Erk-mediated proliferation and anti-apoptotic signalling. DARPP-32 isoforms are overexpressed in SCLC patient-derived tumour tissue, but undetectable in physiologically normal lung. Achaete-scute homologue 1 (ASCL1) transcriptionally activates DARPP-32 isoforms in human SCLC cells. Conclusions We reveal new regulatory mechanisms of SCLC oncogenesis that suggest DARPP-32 isoforms may represent a negative prognostic indicator for SCLC and serve as a potential target for the development of new therapies.
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Affiliation(s)
- Sk Kayum Alam
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Li Wang
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | - Yanan Ren
- The Hormel Institute, University of Minnesota, Austin, MN, USA
| | | | - Farhad Kosari
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Anja C Roden
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Rendong Yang
- The Hormel Institute, University of Minnesota, Austin, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Luke H Hoeppner
- The Hormel Institute, University of Minnesota, Austin, MN, USA. .,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
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Avanes A, Lenz G, Momand J. Darpp-32 and t-Darpp protein products of PPP1R1B: Old dogs with new tricks. Biochem Pharmacol 2018; 160:71-79. [PMID: 30552871 DOI: 10.1016/j.bcp.2018.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 12/11/2018] [Indexed: 02/07/2023]
Abstract
The PPP1R1B gene is located on chromosome 17q12 (39,626,208-39,636,626[GRCh38/hg38]), which codes for multiple transcripts and two experimentally-documented proteins Darpp-32 and t-Darpp. Darpp-32 (Dopamine and cAMP Regulated Phosphoprotein), discovered in the early 1980s, is a protein whose phosphorylation is upregulated in response to cAMP in dopamine-responsive tissues in the brain. It's phosphorylation profile modulates its ability to bind and inhibit Protein Phosphatase 1 activity, which, in turn, controls the activity of hundreds of phosphorylated proteins. PPP1R1B knockout mice exhibit subtle learning defects. In 2002, the second protein product of PPP1R1B was discovered in gastric cancers: t-Darpp (truncated Darpp-32). The start codon of t-Darpp is amino acid residue 37 of Darpp-32 and it lacks the domain responsible for modulating Protein Phosphatase 1. Aside from gastric cancers, t-Darpp and/or Darpp-32 is overexpressed in tumor cells from breast, colon, esophagus, lung and prostate tissues. More than one research team has demonstrated that these proteins, through mechanisms that to date remain cloudy, activate AKT, a protein whose phosphorylation leads to cell survival and blocks apoptosis. Furthermore, in Her2 positive breast cancers (an aggressive form of breast cancer), t-Darpp/Darpp-32 overexpression causes resistance to the frequently-administered anti-Her2 drug, trastuzumab (Herceptin), likely through AKT activation. Here we briefly describe how Darpp-32 and t-Darpp were discovered and report on the current state of knowledge of their involvement in cancers. We present a case for the development of an anti-t-Darpp therapeutic agent and outline the unique challenges this endeavor will likely encounter.
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Affiliation(s)
- Arabo Avanes
- Department of Chemistry and Biochemistry, California State University Los Angeles, CA, USA
| | - Gal Lenz
- Department of Cancer Biology, City of Hope, CA 91010, USA.
| | - Jamil Momand
- Department of Chemistry and Biochemistry, California State University Los Angeles, CA, USA.
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t-Darpp stimulates protein kinase A activity by forming a complex with its RI regulatory subunit. Cell Signal 2017; 40:53-61. [PMID: 28867659 DOI: 10.1016/j.cellsig.2017.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 02/05/2023]
Abstract
t-Darpp is the truncated form of the dopamine- and cAMP-regulated phosphoprotein of 32kDa (Darpp-32) and has been demonstrated to confer resistance to trastuzumab, a Her2-targeted anticancer agent, via sustained signaling through the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt pathway and activation of protein kinase A (PKA). The mechanism of t-Darpp-mediated PKA activation is poorly understood. In the PKA holoenzyme, when the catalytic subunits are bound to regulatory subunits RI or RII, kinase activity is inhibited. We investigated PKA activity and holoenzyme composition in cell lines overexpressing t-Darpp (SK.tDp) or a T39A phosphorylation mutant (SK.tDpT39A), as well as an empty vector control cell line (SK.empty). We also evaluated protein-protein interactions between t-Darpp and PKA catalytic (PKAc) or regulatory subunits RI and RII in those cell lines. SK.tDp cells had elevated PKA activity and showed diminished association of RI with PKAc, whereas SK.tDpT39A cells did not have these properties. Moreover, wild type t-Darpp associates with RI. Concurrent expression of Darpp-32 reversed t-Darrp's effects on PKA holoenzyme state, consistent with earlier observations that Darpp-32 reverses t-Darpp's activation of PKA. Together, t-Darpp phosphorylation at T39 seems to be crucial for t-Darpp-mediated PKA activation and this activation appears to occur through an association with RI and sequestering of RI away from PKAc. The t-Darpp-RI interaction could be a druggable target to reduce PKA activity in drug-resistant cancer.
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