ORCID Profile
0000-0003-0237-0745
Current Organisation
Karl Landsteiner University of Health Sciences
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Informa UK Limited
Date: 26-05-2015
Publisher: American Association for Cancer Research (AACR)
Date: 04-2018
DOI: 10.1158/2326-6066.CIR-17-0183
Abstract: Cyclin-dependent kinase 8 (CDK8) is a member of the transcription-regulating CDK family. CDK8 activates or represses transcription by associating with the mediator complex or by regulating transcription factors. Oncogenic activity of CDK8 has been demonstrated in several cancer types. Targeting CDK8 represents a potential therapeutic strategy. Because knockdown of CDK8 in a natural killer (NK) cell line enhances cytotoxicity and NK cells provide the first line of immune defense against transformed cells, we asked whether inhibiting CDK8 would improve NK-cell antitumor responses. In this study, we investigated the role of CDK8 in NK-cell function in vivo using mice with conditional ablation of CDK8 in NKp46+ cells (Cdk8fl/flNcr1Cre). Regardless of CDK8 expression, NK cells develop and mature normally in bone marrow and spleen. However, CDK8 deletion increased expression of the lytic molecule perforin, which correlated with enhanced NK-cell cytotoxicity in vitro. This translates into improved NK cell–mediated tumor surveillance in vivo in three independent models: B16F10 melanoma, v-abl+ lymphoma, and a slowly developing oncogene-driven leukemia. Our results thereby define a suppressive effect of CDK8 on NK-cell activity. Therapies that target CDK8 in cancer patients may enhance NK-cell responses against tumor cells. Cancer Immunol Res 6(4) 458–66. ©2018 AACR.
Publisher: American Association for Cancer Research (AACR)
Date: 04-2016
DOI: 10.1158/2159-8290.CD-15-0732
Abstract: Natural killer (NK) cells are tightly regulated by the JAK–STAT signaling pathway and cannot survive in the absence of STAT5. We now report that STAT5-deficient NK cells can be rescued by overexpression of BCL2. Our experiments define STAT5 as a master regulator of NK-cell proliferation and lytic functions. Although NK cells are generally responsible for killing tumor cells, the rescued STAT5-deficient NK cells promote tumor formation by producing enhanced levels of the angiogenic factor VEGFA. The importance of VEGFA produced by NK cells was verified by experiments with a conditional knockout of VEGFA in NK cells. We show that STAT5 normally represses the transcription of VEGFA in NK cells, in both mice and humans. These findings reveal that STAT5-directed therapies may have negative effects: In addition to impairing NK-cell–mediated tumor surveillance, they may even promote tumor growth by enhancing angiogenesis. Significance: The importance of the immune system in effective cancer treatment is widely recognized. We show that the new signal interceptors targeting the JAK–STAT5 pathway may have dangerous side effects that must be taken into account in clinical trials: inhibiting JAK–STAT5 has the potential to promote tumor growth by enhancing NK-cell–mediated angiogenesis. Cancer Discov 6(4) 414–29. ©2016 AACR. See related commentary by Ni and Cerwenka, p. 347. This article is highlighted in the In This Issue feature, p. 331
No related grants have been discovered for Agnieszka Witalisz-Siepracka.