@article{SchueleinVoelkWolfZhuetal.2014, author = {Sch{\"u}lein-V{\"o}lk, Christina and Wolf, Elmar and Zhu, Jing and Xu, Wenshan and Taranets, Lyudmyla and Hellmann, Andreas and J{\"a}nicke, Laura A. and Diefenbacher, Markus E. and Behrens, Axel and Eilers, Martin and Popov, Nikita}, title = {Dual Regulation of Fbw7 Function and Oncogenic Transformation by Usp28}, series = {CELL REPORTS}, volume = {9}, journal = {CELL REPORTS}, number = {3}, issn = {2211-1247}, doi = {10.1016/j.celrep.2014.09.057}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-118219}, pages = {1099-1109}, year = {2014}, abstract = {Fbw7, the substrate recognition subunit of SCF(Fbw7) ubiquitin ligase, mediates the turnover of multiple proto-oncoproteins and promotes its own degradation. Fbw7-dependent substrate ubiquitination is antagonized by the Usp28 deubiquitinase. Here, we show that Usp28 preferentially antagonizes autocatalytic ubiquitination and stabilizes Fbw7, resulting in dose-dependent effects in Usp28 knockout mice. Monoallelic deletion of Usp28 maintains stable Fbw7 but drives Fbw7 substrate degradation. In contrast, complete knockout triggers Fbw7 degradation and leads to the accumulation of Fbw7 substrates in several tissues and embryonic fibroblasts. On the other hand, overexpression of Usp28 stabilizes both Fbw7 and its substrates. Consequently, both complete loss and ectopic expression of Usp28 promote Ras-driven oncogenic transformation. We propose that dual regulation of Fbw7 activity by Usp28 is a safeguard mechanism for maintaining physiological levels of proto-oncogenic Fbw7 substrates, which is equivalently disrupted by loss or overexpression of Usp28.}, language = {en} } @article{PietroGarciaHartmannReisslandetal.2022, author = {Pietro-Garcia, Christian and Hartmann, Oliver and Reissland, Michaela and Fischer, Thomas and Maier, Carina R. and Rosenfeldt, Mathias and Sch{\"u}lein-V{\"o}lk, Christina and Klann, Kevin and Kalb, Reinhard and Dikic, Ivan and M{\"u}nch, Christian and Diefenbacher, Markus E.}, title = {Inhibition of USP28 overcomes Cisplatin-resistance of squamous tumors by suppression of the Fanconi anemia pathway}, series = {Cell Death and Differentiation}, volume = {29}, journal = {Cell Death and Differentiation}, number = {3}, issn = {1476-5403}, doi = {10.1038/s41418-021-00875-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-273014}, pages = {568-584}, year = {2022}, abstract = {Squamous cell carcinomas (SCC) frequently have an exceptionally high mutational burden. As consequence, they rapidly develop resistance to platinum-based chemotherapy and overall survival is limited. Novel therapeutic strategies are therefore urgently required. SCC express ∆Np63, which regulates the Fanconi Anemia (FA) DNA-damage response in cancer cells, thereby contributing to chemotherapy-resistance. Here we report that the deubiquitylase USP28 is recruited to sites of DNA damage in cisplatin-treated cells. ATR phosphorylates USP28 and increases its enzymatic activity. This phosphorylation event is required to positively regulate the DNA damage repair in SCC by stabilizing ∆Np63. Knock-down or inhibition of USP28 by a specific inhibitor weakens the ability of SCC to cope with DNA damage during platin-based chemotherapy. Hence, our study presents a novel mechanism by which ∆Np63 expressing SCC can be targeted to overcome chemotherapy resistance. Limited treatment options and low response rates to chemotherapy are particularly common in patients with squamous cancer. The SCC specific transcription factor ∆Np63 enhances the expression of Fanconi Anemia genes, thereby contributing to recombinational DNA repair and Cisplatin resistance. Targeting the USP28-∆Np63 axis in SCC tones down this DNA damage response pathways, thereby sensitizing SCC cells to cisplatin treatment.}, language = {en} } @article{FischerHartmannReisslandetal.2022, author = {Fischer, Thomas and Hartmann, Oliver and Reissland, Michaela and Prieto-Garcia, Cristian and Klann, Kevin and Pahor, Nikolett and Sch{\"u}lein-V{\"o}lk, Christina and Baluapuri, Apoorva and Polat, B{\"u}lent and Abazari, Arya and Gerhard-Hartmann, Elena and Kopp, Hans-Georg and Essmann, Frank and Rosenfeldt, Mathias and M{\"u}nch, Christian and Flentje, Michael and Diefenbacher, Markus E.}, title = {PTEN mutant non-small cell lung cancer require ATM to suppress pro-apoptotic signalling and evade radiotherapy}, series = {Cell \& Bioscience}, volume = {12}, journal = {Cell \& Bioscience}, issn = {2045-3701}, doi = {10.1186/s13578-022-00778-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-299865}, year = {2022}, abstract = {Background Despite advances in treatment of patients with non-small cell lung cancer, carriers of certain genetic alterations are prone to failure. One such factor frequently mutated, is the tumor suppressor PTEN. These tumors are supposed to be more resistant to radiation, chemo- and immunotherapy. Results We demonstrate that loss of PTEN led to altered expression of transcriptional programs which directly regulate therapy resistance, resulting in establishment of radiation resistance. While PTEN-deficient tumor cells were not dependent on DNA-PK for IR resistance nor activated ATR during IR, they showed a significant dependence for the DNA damage kinase ATM. Pharmacologic inhibition of ATM, via KU-60019 and AZD1390 at non-toxic doses, restored and even synergized with IR in PTEN-deficient human and murine NSCLC cells as well in a multicellular organotypic ex vivo tumor model. Conclusion PTEN tumors are addicted to ATM to detect and repair radiation induced DNA damage. This creates an exploitable bottleneck. At least in cellulo and ex vivo we show that low concentration of ATM inhibitor is able to synergise with IR to treat PTEN-deficient tumors in genetically well-defined IR resistant lung cancer models.}, language = {en} } @article{PrietoGarciaHartmannReisslandetal.2022, author = {Prieto-Garcia, Cristian and Hartmann, Oliver and Reissland, Michaela and Braun, Fabian and Bozkurt, S{\"u}leyman and Pahor, Nikolett and Fuss, Carmina and Schirbel, Andreas and Sch{\"u}lein-V{\"o}lk, Christina and Buchberger, Alexander and Calzado Canale, Marco A. and Rosenfeldt, Mathias and Dikic, Ivan and M{\"u}nch, Christian and Diefenbacher, Markus E.}, title = {USP28 enables oncogenic transformation of respiratory cells, and its inhibition potentiates molecular therapy targeting mutant EGFR, BRAF and PI3K}, series = {Molecular Oncology}, volume = {16}, journal = {Molecular Oncology}, number = {17}, doi = {10.1002/1878-0261.13217}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312777}, pages = {3082-3106}, year = {2022}, abstract = {Oncogenic transformation of lung epithelial cells is a multistep process, frequently starting with the inactivation of tumour suppressors and subsequent development of activating mutations in proto-oncogenes, such as members of the PI3K or MAPK families. Cells undergoing transformation have to adjust to changes, including altered metabolic requirements. This is achieved, in part, by modulating the protein abundance of transcription factors. Here, we report that the ubiquitin carboxyl-terminal hydrolase 28 (USP28) enables oncogenic reprogramming by regulating the protein abundance of proto-oncogenes such as c-JUN, c-MYC, NOTCH and ∆NP63 at early stages of malignant transformation. USP28 levels are increased in cancer compared with in normal cells due to a feed-forward loop, driven by increased amounts of oncogenic transcription factors such as c-MYC and c-JUN. Irrespective of oncogenic driver, interference with USP28 abundance or activity suppresses growth and survival of transformed lung cells. Furthermore, inhibition of USP28 via a small-molecule inhibitor resets the proteome of transformed cells towards a 'premalignant' state, and its inhibition synergizes with clinically established compounds used to target EGFR\(^{L858R}\)-, BRAF\(^{V600E}\)- or PI3K\(^{H1047R}\)-driven tumour cells. Targeting USP28 protein abundance at an early stage via inhibition of its activity is therefore a feasible strategy for the treatment of early-stage lung tumours, and the observed synergism with current standard-of-care inhibitors holds the potential for improved targeting of established tumours.}, language = {en} } @article{Prieto‐GarciaHartmannReisslandetal.2020, author = {Prieto-Garcia, Cristian and Hartmann, Oliver and Reissland, Michaela and Braun, Fabian and Fischer, Thomas and Walz, Susanne and Sch{\"u}lein-V{\"o}lk, Christina and Eilers, Ursula and Ade, Carsten P. and Calzado, Marco A. and Orian, Amir and Maric, Hans M. and M{\"u}nch, Christian and Rosenfeldt, Mathias and Eilers, Martin and Diefenbacher, Markus E.}, title = {Maintaining protein stability of ∆Np63 via USP28 is required by squamous cancer cells}, series = {EMBO Molecular Medicine}, volume = {12}, journal = {EMBO Molecular Medicine}, number = {4}, doi = {10.15252/emmm.201911101}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218303}, year = {2020}, abstract = {The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ∆Np63 and maintains elevated ∆NP63 levels in SCC by counteracting its proteasome-mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ∆Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.}, language = {en} }