Frameshift mutation in the Dok1 gene in chronic lymphocytic leukemia

Lee, Sanghoon; Roy, François; Galmarini, Carlos M.; Accardi, Rosita; Michelon, Jocelyne; Viller, Alexandra; Cros, Emeline; Dumontet, Charles; Sylla, Bakary S.

doi:10.1038/sj.onc.1207385

Cited by 25 publications

(55 citation statements)

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“…All results are the mean Ϯ S.E. 16). For example, overexpression of wild type DOK1 inhibited PDGF-induced MAPK activation (16) as well as Ras and Erk activation induced by glial cell-derived neurotrophic factor in human neuroectodermal tumor cell lines (14).…”

Section: Discussionmentioning

confidence: 99%

DOK1 Mediates SHP-2 Binding to the αVβ3 Integrin and Thereby Regulates Insulin-like Growth Factor I Signaling in Cultured Vascular Smooth Muscle Cells

Ling

Maile

Badley-Clarke

et al. 2005

Journal of Biological Chemistry

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Recruitment of the Src homology 2 domain tyrosine phosphatase (SHP-2) to the phosphorylated ␤3 subunit of the ␣V␤3 integrin is required for insulin-like growth factor I (IGF-I)-stimulated cell migration and proliferation in vascular smooth muscle cells. Because SHP-2 does not bind directly to ␤3, we attempted to identify a linker protein that could mediate SHP-2/␤3 association. DOK1 is a member of insulin receptor substrate protein family that binds ␤3 and contains YXXL/I motifs that are potential binding sites for SHP-2. Our results show that IGF-I induces DOK1 binding to ␤3 and to SHP-2. Preincubation of cells with synthetic peptides that blocked either DOK1/␤3 or DOK1/SHP-2 association inhibited SHP-2 recruitment to ␤3. Expression of a DOK1 mutant that does not bind to ␤3 also disrupts SHP-2/␤3 association. As a result of SHP-2/␤3 disruption, IGF-I dependent phosphorylation of Akt and p44/p42 mitogen-activated protein kinase and its ability to stimulate cell migration and proliferation were significantly impaired. These results demonstrate that DOK1 mediates SHP-2/␤3 association in response to IGF-I thereby mediating the effect of integrin ligand occupancy on IGF-IR-linked signaling in smooth muscle cells. Vascular smooth muscle cell (SMC)1 migration and proliferation play significant roles in atherosclerotic plaque formation (1). Insulin-like growth factor I (IGF-I) is a potent stimulant of SMC migration and proliferation responses (2). We have shown previously that ligand occupancy of the ␣V␤3 integrin is required for SMC to respond appropriately to IGF-I (3). Blocking the ligand occupancy of ␣V␤3 inhibits IGF-I-dependent downstream signaling including phosphorylation of IRS-1 (3) and the trans-membrane, scaffolding protein Src homology 2 domain containing protein-tyrosine phosphatase substrate-1 (SHPS-1), as well as cell migration and proliferation (4). One important event that occurs in response to ligand occupancy of ␣V␤3 is the phosphorylation of the ␤3 subunit, and previous studies have shown that this is required for IGF-I-dependent signaling and biologic actions (5). SMCs expressing a mutant form of ␤3 in which the two tyrosines in the cytoplasmic domain of ␤3 were substituted with phenylalanines did not respond to IGF-I with an increase in DNA synthesis (5). Therefore in SMC phosphorylation of the ␤3 subunit of ␣V␤3 integrin plays a key role in regulating IGF-I dependent cellular responses.Our prior studies have shown that ligand occupancy of ␣V␤3 regulates IGF-IR signaling by regulating the transfer of the protein-tyrosine phosphatase SHP-2 (4, 5). In high density cultures, the ␤3 subunit is constitutively tyrosine phosphorylated and Src homology 2 domain tyrosine phosphatase (SHP-2) can be co-immunoprecipitated with phosphorylated ␤3 (5). This association correlates with membrane localization of SHP-2 and is required for the subsequent transfer of SHP-2 to its membrane substrate protein SHPS-1 following IGF-I stimulation (5). The disruption of SHP-2 and ␤3 association results in the elimination of...

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Section: Discussionmentioning

confidence: 99%

DOK1 Mediates SHP-2 Binding to the αVβ3 Integrin and Thereby Regulates Insulin-like Growth Factor I Signaling in Cultured Vascular Smooth Muscle Cells

Ling

Maile

Badley-Clarke

et al. 2005

Journal of Biological Chemistry

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“…In addition, the DOK1 gene locus is localized in human chromosome 2p13, which is frequently rearranged in various human tumors (11,22,34). Indeed, we reported a frameshift mutation of the DOK1 gene in chronic lymphocytic leukemia (CLL), resulting in truncated DOK1 found exclusively in the nucleus, in contrast to the cytoplasmic wild-type protein (16). Consistent with these findings, we discovered that DOK1 harbors a nuclear exclusion site (NES) that allows it to shuttle between the cytoplasm and the nucleus (16).…”

mentioning

confidence: 99%

“…Indeed, we reported a frameshift mutation of the DOK1 gene in chronic lymphocytic leukemia (CLL), resulting in truncated DOK1 found exclusively in the nucleus, in contrast to the cytoplasmic wild-type protein (16). Consistent with these findings, we discovered that DOK1 harbors a nuclear exclusion site (NES) that allows it to shuttle between the cytoplasm and the nucleus (16). Interestingly, a constitutive nuclear DOK1-NES mutant was found to be defective in its abilities to inhibit cell proliferation and promote cell spreading (16).…”

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confidence: 99%

Transcriptional Regulation of the Human Tumor Suppressor DOK1 by E2F1

Siouda

Yue

Shukla

et al. 2012

Molecular and Cellular Biology

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The expression of the tumor suppressor DOK1 is repressed in a variety of human tumors as a result of hypermethylation of its promoter region. However, the molecular mechanisms by which DOK1 expression is regulated have been poorly investigated. Here, we show that the expression of DOK1 is regulated mainly by the transcription factor E2F1. We identified three putative E2F1 response elements (EREs) in the DOK1 promoter region. E2F1 had a relatively higher binding affinity for the ERE located between bp ؊498 and ؊486 compared with the other two EREs. E2F1 gene silencing strongly inhibited DOK1 expression. E2F1-driven DOK1 transcription occurred in the presence of cellular stresses, such as accumulation of DNA damage induced by etoposide. DOK1 silencing promoted cell proliferation and protected against etoposide-induced apoptosis, indicating that DOK1 acts as a key mediator of cellular stress-induced cell death. Most importantly, we observed that DNA methylation of the DOK1 core promoter region found in head and neck cancer cell lines hampered the recruitment of E2F1 to the DOK1 promoter and compromised DOK1 expression. In summary, our data show that E2F1 is a key factor in DOK1 expression and provide novel insights into the regulation of these events in cancer cells.

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“…Principally based on patterns of expression, two sub-groups exist within the DOK family. DOK-1, DOK-2 and DOK-3 comprise one sub-group primarily expressed in haematopoietic tissues [7,9,11,[23][24][25][26][27][28] , whereas, DOK-4, DOK-5 and DOK-6 are expressed in nonhaematopoietic tissues, predominantly within the nervous system [2][3][4][29][30][31][32][33] . Separately, expression of DOK-7 is concentrated to skeletal muscle and the heart [34,35] .…”

Section: Introductionmentioning

confidence: 99%

“…Tyrosine-kinase inhibitors targeted against EGFR are currently in use for breast cancer treatment whilst several against c-Src are being trialled [20,[39][40][41] . Since DOK-1 association with CML, down-regulation of the DOK-1, DOK-2 and DOK-3 sub-group has been linked with several other haematopoietic cancers, including histiocytic sarcoma and Burkitt's lymphoma [6,7,9,[24][25][26] . Investigation into non-haematopoietic tissues identified lung adenocarcinoma development in DOK-1, DOK-2 and DOK-3 knockout mice and down regulation of DOK-2 expression in human lung cancer [1] .…”

Section: Introductionmentioning

confidence: 99%

mRNA expression of DOK1-6 in human breast cancer

Ghanem

Bracken

Kasem

et al. 2014

WJCO

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AIM:To examine the expression of downstream of tyrosine kinase (DOK)1-6 genes in normal and breast cancer tissue and correlated this with several clinicopathological and prognostic factors.METHODS: DOK1-6 mRNA extraction and reverse transcription were performed on fresh frozen breast cancer tissue samples (n = 112) and normal background breast tissue (n = 31). Tissues were collected between 1991 and 1996 at two centres and all patients underwent mastectomy and ipsilateral axillary node dissection. All tissues were randomly numbered and the details were only made known after all analyses were completed. Transcript levels of expression were determined using real-time polymerase chain reaction and analyzed against TNM stage, tumour grade and clinical outcome over a 10-year follow-up period.RESULTS: DOK-2 and DOK-6 expression decreased with increasing TNM stage. DOK-6 expression decreased with increasing Nottingham Prognostic Index (NPI) [NPI-1 vs NPI-3 (mean copy number 15.4 vs 0.22, 95%CI: 2.7-27.6, P = 0.018) and NPI-2 vs NPI-3 (mean copy number 7.6 vs 0.22, 95%CI: 0.1-14.6, P = 0.048)].After a median follow up period of 10 years, higher levels of DOK-2 expression were found among patients who remained disease-free compared to those who developed local or distant recurrence (mean copy number 3.94 vs 0.0000096, 95%CI: 1.0-6.85, P = 0.0091), and distant recurrence (mean copy number 3.94 vs 0.0025, 95%CI: 1.0-6.84, P = 0.0092). Patients who remained disease-free had higher levels of DOK-6 expression compared to those who died from breast cancer. CONCLUSION:Decreasing expression levels of DOK-2 and DOK-6 with increased breast tumour progression supports the notion that DOK-2 and DOK-6 behave as tumour suppressors in human breast cancer.

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Frameshift mutation in the Dok1 gene in chronic lymphocytic leukemia

Cited by 25 publications

References 50 publications

DOK1 Mediates SHP-2 Binding to the αVβ3 Integrin and Thereby Regulates Insulin-like Growth Factor I Signaling in Cultured Vascular Smooth Muscle Cells

DOK1 Mediates SHP-2 Binding to the αVβ3 Integrin and Thereby Regulates Insulin-like Growth Factor I Signaling in Cultured Vascular Smooth Muscle Cells

Transcriptional Regulation of the Human Tumor Suppressor DOK1 by E2F1

mRNA expression of DOK1-6 in human breast cancer

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