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Damavandi Z, Riahi P, Majidizadeh T, Houshmand M. Evaluation of t-DARPP Expression Alteration in Association with DDR1 Expression in Non-Small Cell Lung Cancer. IRANIAN BIOMEDICAL JOURNAL 2024; 28:23-30. [PMID: 38308500 PMCID: PMC10994641 DOI: 10.61186/ibj.3878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 06/21/2023] [Indexed: 02/04/2024]
Abstract
Background Discoidin domain receptor 1 (DDR1) signaling plays a critical role in various cellular functions. Increased DDR1 expression has been shown in different human cancers. t-DARPP is a truncated isoform of DARPP-32, and its upregulation promotes cell survival and migration. Most lung cancer patients have non-small cell lung cancer (NSCLC), and their survival rate is low. Therefore, it is necessary to study new and effective targeted therapies. Increased t-DARPP expression in NSCLC patients is associated with patient survival and can act as a prognostic marker correlated with increasing stages of NSCLC. The current study aimed to evaluate alteration in DDR1 expression and its effects on t-DARPP expression in NSCLC. Methods Two human lung adenocarcinoma cell lines, A549 and Calu-3, were treated with collagen type I and transfected with DDR1 siRNA. The relative expression of DDR1 and t-DARPP was evaluated using qRT-PCR. Results The results indicated that collagen type I could stimulate DDR1 expression in NSCLC cells. Also, DDR1 upregulation resulted in a significant increase in t-DARPP expression. In contrast, suppression of DDR1 expression significantly decreased t-DARPP expression. Conclusion Our findings propose that modification in the expression of DDR1, caused by collagen type I and siRNA, might influence the expression of t-DARPP in NSCLC that is linked to NSCLC progression. Moreover, this alteration could potentially serve as an innovative target for therapeutic intervention.
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Affiliation(s)
| | | | | | - Massoud Houshmand
- Department of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
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2
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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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Rigalli JP, Theile D, Nilles J, Weiss J. Regulation of PXR Function by Coactivator and Corepressor Proteins: Ligand Binding Is Just the Beginning. Cells 2021; 10:cells10113137. [PMID: 34831358 PMCID: PMC8625645 DOI: 10.3390/cells10113137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/13/2022] Open
Abstract
The pregnane X receptor (PXR, NR1I2) is a nuclear receptor which exerts its regulatory function by heterodimerization with the retinoid-X-receptor α (RXRα, NR2B1) and binding to the promoter and enhancer regions of diverse target genes. PXR is involved in the regulation of drug metabolism and excretion, metabolic and immunological functions and cancer pathogenesis. PXR activity is strongly regulated by the association with coactivator and corepressor proteins. Coactivator proteins exhibit histone acetyltransferase or histone methyltransferase activity or associate with proteins having one of these activities, thus promoting chromatin decondensation and activation of the gene expression. On the contrary, corepressor proteins promote histone deacetylation and therefore favor chromatin condensation and repression of the gene expression. Several studies pointed to clear cell- and ligand-specific differences in the activation of PXR. In this article, we will review the critical role of coactivator and corepressor proteins as molecular determinants of the specificity of PXR-mediated effects. As already known for other nuclear receptors, understanding the complex mechanism of PXR activation in each cell type and under particular physiological and pathophysiological conditions may lead to the development of selective modulators with therapeutic potential.
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4
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Wang Z, Wang L, Jiang R, Li C, Chen X, Xiao H, Hou J, Hu L, Huang C, Wang Y. Ginsenoside Rg1 prevents bone marrow mesenchymal stem cell senescence via NRF2 and PI3K/Akt signaling. Free Radic Biol Med 2021; 174:182-194. [PMID: 34364981 DOI: 10.1016/j.freeradbiomed.2021.08.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 07/18/2021] [Accepted: 08/05/2021] [Indexed: 12/13/2022]
Abstract
Senescence limits the characteristics and functionality of mesenchymal stem cells (MSCs), thereby severely restricting their application in tissue engineering. Here, we investigated ways to prevent MSCs from entering a state of senescence. We found that Rg1, an extract of natural ginseng, can reduce the expression of senescence markers in cultured cells in vitro and in various tissues in vivo. Simultaneously, ginsenoside Rg1 improved the antioxidant capacity of cells, and the senescence-inhibiting and antioxidant effect of Rg1 were associated with the activation of the nuclear factor E2-related factor 2 (NRF2) signaling pathway. Furthermore, Rg1 may activate the NRF2 pathway by increasing the interaction between P62 and KEAP1through P62 upregulation and AKT activation. Taken together, our findings indicate that Rg1 prevents cell senescence via NRF2 and AKT, and activation of AKT or NRF2 may thus represent therapeutic targets for preventing cell senescence.
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Affiliation(s)
- Ziling Wang
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Lu Wang
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Rong Jiang
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Chang Li
- Department of Cardiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China; Institute of Life Science, Chongqing Medical University, Chongqing, 400016, China
| | - Xiongbin Chen
- Department of Anatomy and Histology and Embryology, Basic Medical College, Chengdu University of Traditional Chinese Medicine, Sichuan, 610075, China
| | - Hanxianzhi Xiao
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Jiying Hou
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Ling Hu
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Caihong Huang
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China
| | - Yaping Wang
- Laboratory of Stem Cells and Tissue Engineering, Department of Histology and Embryology, Chongqing Medical University, Chongqing, 400016, China.
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5
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Murad R, Avanes A, Ma X, Geng S, Mortazavi A, Momand J. Transcriptome and chromatin landscape changes associated with trastuzumab resistance in HER2+ breast cancer cells. Gene 2021; 799:145808. [PMID: 34224831 DOI: 10.1016/j.gene.2021.145808] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 05/29/2021] [Accepted: 06/30/2021] [Indexed: 12/09/2022]
Abstract
We set out to uncover transcriptome and chromatin landscape changes that occur in HER2 + breast cancer (BC) cells upon acquiring resistance to trastuzumab. RNA-seq analysis was applied to two independently-derived BC cell lines with acquired resistance to trastuzumab (SKBr3.HerR and BT-474HerR) and their parental drug-sensitive cell lines (SKBr3 and BT-474). Chromatin landscape analysis indicated that the most significant increase in accessibility in resistant cells occurs in PPP1R1B within a segment spanning introns 1b through intron 3. Footprint analysis of this segment revealed that FoxJ3 (within intron 2) and Pou5A1/Sox2 (within inton 3) transcription factor motifs are protected in resistant cells. Overall, 344 shared genes were upregulated in both resistant cell lines relative to their parental counterparts and 453 shared genes were downregulated in both resistant cell lines relative to their parental counterparts. In resistant cells, genes associated with autophagy and mitochondria organization are upregulated and genes associated with ribosome assembly and cell cycle are downregulated relative to parental cells. The five top upregulated genes in drug-resistant breast cancer cells are APOD, AZGP1, ETV5, ALPP, and PPP1R1B. This is the first report of increased chromatin accessibility within PPP1R1B associated with its t-Darpp transcript increase, and points to a possible mechanism for its activation in trastuzumab-resistant cells.
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Affiliation(s)
- Rabi Murad
- Department of Developmental & Cell Biology, University of California Irvine, Irvine, CA 92617, USA
| | - Arabo Avanes
- Department of Chemistry and Biochemistry, California State University Los Angeles, Los Angeles, CA 90032, USA
| | - Xinyi Ma
- Department of Developmental & Cell Biology, University of California Irvine, Irvine, CA 92617, USA
| | - Shuhui Geng
- Department of Chemistry and Biochemistry, California State University Los Angeles, Los Angeles, CA 90032, USA
| | - Ali Mortazavi
- Department of Developmental & Cell Biology, University of California Irvine, Irvine, CA 92617, USA.
| | - Jamil Momand
- Department of Chemistry and Biochemistry, California State University Los Angeles, Los Angeles, CA 90032, USA.
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Saidy B, Kotecha S, Butler A, Rakha EA, Ellis IO, Green AR, Martin SG, Storr SJ. PP1, PKA and DARPP-32 in breast cancer: A retrospective assessment of protein and mRNA expression. J Cell Mol Med 2021; 25:5015-5024. [PMID: 33991172 PMCID: PMC8178272 DOI: 10.1111/jcmm.16447] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/22/2021] [Accepted: 02/24/2021] [Indexed: 12/28/2022] Open
Abstract
Cyclic AMP–dependent protein kinase A (PKA) and protein phosphatase 1 (PP1) are proteins involved in numerous essential signalling pathways that modulate physiological and pathological functions. Both PP1 and PKA can be inhibited by dopamine‐ and cAMP‐regulated phosphoprotein 32 kD (DARPP‐32). Using immunohistochemistry, PKA and PP1 expression was determined in a large primary breast tumour cohort to evaluate associations between clinical outcome and clinicopathological criteria (n > 1100). In addition, mRNA expression of PKA and PP1 subunits was assessed in the METABRIC data set (n = 1980). Low protein expression of PKA was significantly associated with adverse survival of breast cancer patients; interestingly, this relationship was stronger in ER‐positive breast cancer patients. PP1 protein expression was not associated with patient survival. PKA and PP1 subunit mRNA was also assessed; PPP1CA, PRKACG and PRKAR1B were associated with breast cancer–specific survival. In patients with high expression of DARPP‐32, low expression of PP1 was associated with adverse survival when compared to high expression in the same group. PKA expression and PP1 expression are of significant interest in cancer as they are involved in a wide array of cellular processes, and these data indicate PKA and PP1 may play an important role in patient outcome.
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Affiliation(s)
- Behnaz Saidy
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Shreeya Kotecha
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Anna Butler
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Emad A Rakha
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Ian O Ellis
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Andrew R Green
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Stewart G Martin
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Sarah J Storr
- Division of Cancer and Stem Cells, Nottingham Breast Cancer Research Centre, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
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Zhang Y, Liu D, Xue F, Yu H, Wu H, Cui X, Zhang X, Wang H. Anti-Malignant Ascites Effect of Total Diterpenoids from Euphorbiae Ebracteolatae Radix Is Attributable to Alterations of Aquaporins via Inhibiting PKC Activity in the Kidney. Molecules 2021; 26:molecules26040942. [PMID: 33578967 PMCID: PMC7916655 DOI: 10.3390/molecules26040942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/05/2021] [Accepted: 02/07/2021] [Indexed: 01/16/2023] Open
Abstract
This study evaluated the anti-ascites effect of total diterpenoids extracted from Euphorbiae ebracteolatae Radix (TDEE) on malignant ascitic mice and elucidated its underlying mechanism. TDEE was extracted by dichloromethane and subjected to column chromatography. The purity of six diterpenoids isolated from TDEE was determined to be 77.18% by HPLC. TDEE (3 and 0.6 g raw herbs/kg, p.o.) reduced ascites and increased urine output. Meanwhile, analysis of tumor cell viability, cycle and apoptosis indicated that TDEE had no antitumor activity. In addition, the expression levels of aquaporins (AQPs) and the membrane translocation levels of protein kinase C (PKC) α and PKCβ in kidney and cells were measured. TDEE reduced the levels of AQP1–4, and inhibited PKCβ expression in membrane fraction. Four main diterpenoids, except compound 2, reduced AQP1 level in human kidney-2 cells. Compounds 4 and 5 inhibited AQP2–4 expression in murine inner medullary collecting duct cells. The diterpenoid-induced inhibition of AQP1–4 expression was blocked by phorbol-12-myristate-13-acetate (PMA; agonist of PKC). The diterpenoids from TDEE are the main anti-ascites components. The anti-ascites effect of diterpenoids may be associated with alterations in AQPs in the kidneys to promote diuresis. The inhibition of AQP1–4 expression by TDEE is related to the inhibition of PKCβ activation.
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Affiliation(s)
- Yuanbin Zhang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Dongfang Liu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Fan Xue
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Hongli Yu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
- Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Engineering Center of State Ministry of Education for Standardization of Chinese Medicine Processing, Nanjing 210023, China
- State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Correspondence: or (H.Y.); or (H.W.); Tel.: +86-025-8679-8281 (H.Y.); +86-025-8581-1206 (H.W.)
| | - Hao Wu
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
- Jiangsu Key Laboratory of Chinese Medicine Processing, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Engineering Center of State Ministry of Education for Standardization of Chinese Medicine Processing, Nanjing 210023, China
- State Key Laboratory Cultivation Base for TCM Quality and Efficacy, Nanjing University of Chinese Medicine, Nanjing 210023, China
- Correspondence: or (H.Y.); or (H.W.); Tel.: +86-025-8679-8281 (H.Y.); +86-025-8581-1206 (H.W.)
| | - Xiaobing Cui
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Xingde Zhang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
| | - Hepeng Wang
- School of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, China; (Y.Z.); (D.L.); (F.X.); (X.C.); (X.Z.); (H.W.)
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Dopamine and cAMP-regulated phosphoprotein 32 kDa (DARPP-32) and survival in breast cancer: a retrospective analysis of protein and mRNA expression. Sci Rep 2019; 9:16987. [PMID: 31740718 PMCID: PMC6861271 DOI: 10.1038/s41598-019-53529-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 10/21/2019] [Indexed: 01/16/2023] Open
Abstract
Dopamine and cAMP regulated phosphoprotein 32 kDa (DARPP-32) also known as phosphoprotein phosphatase-1 regulatory subunit 1B and encoded by the PPP1R1B gene is an inhibitor of protein phosphatase-1 and protein kinase A. DARPP-32 is expressed in a wide range of epithelial cells and some solid tumours; however, its role in breast cancer is only partially defined. DARPP-32 expression was determined using immunohistochemistry in two independent cohorts of early stage invasive breast cancer patients (discovery n = 1352; validation n = 1655), and 112 HER2 positive breast cancer patients treated with trastuzumab and adjuvant chemotherapy. PPP1R1B mRNA expression was assessed in the METABRIC cohort (n = 1980), using artificial neural network analysis to identify associated genes. In the discovery cohort, low nuclear expression of DARPP-32 was significantly associated with shorter survival (P = 0.041), which was independent of other prognostic variables (P = 0.019). In the validation cohort, low cytoplasmic and nuclear expression was significantly associated with shorter survival (both P = 0.002), with cytoplasmic expression independent of other prognostic variables (P = 0.023). Stronger associations with survival in oestrogen receptor (ER) positive disease were observed. In patients treated with trastuzumab, low nuclear expression was significantly associated with adverse progression-free survival (P = 0.031). In the METABRIC cohort, low PPP1R1B expression was associated with shortened survival of ER positive patients. Expression of CDC42 and GRB7, amongst others, were associated with PPP1R1B expression. This data suggests a role for DARPP-32 as a prognostic marker with clinical utility in breast cancer.
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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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