Biology subjects

Schuelein-Voelk, C.

Publications and source records attributed to Schuelein-Voelk, C..

3 recordsLinked to original sources

bioRxiv2021

USP28 enables oncogenic transformation of respiratory cells and its inhibition potentiates molecular therapy targeting mutant EGFR, BRAF and PI3K.

Oncogenic transformation of lung epithelial cells is a multi-step process, frequently starting with the inactivation of tumor suppressors and subsequent activating mutations in proto-oncogenes, such as members of the PI3K or MAPK family. Cells undergoing transformation have to adjust to changes, such as metabolic requirements. This is achieved, in part, by modulating the protein abundance of transcription factors, which manifest these adjustments. Here, we report that the deubiquitylase USP28 enables oncogenic reprogramming by regulating the protein abundance of proto-oncogenes, such as c-JUN, c-MYC, NOTCH and {Delta}NP63, at early stages of malignant transformation. USP28 is increased in cancer compared to 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 reset the proteome of transformed cells towards a pre-malignant state, and its inhibition cooperated with clinically established compounds used to target EGFRL858R, BRAFV600E or PI3KH1047R driven tumor cells. Targeting USP28 protein abundance already at an early stage via inhibition of its activity therefore is 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 tumors.

cancer biology↗

bioRxiv2021

PTEN mutant NSCLC require ATM to suppress pro-apoptotic signalling and evade radiotherapy

BackgroundDespite 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. MethodsUsing CRISPR genome editing, we deleted PTEN in a human tracheal stem cell-like cell line as well generated primary murine NSCLC, proficient or deficient for Pten, in vivo. These models were used to verify the impact of PTEN loss in vitro and in vivo by immunohistochemical staining, western blot and RNA-Sequencing. Radiation sensitivity was assessed by colony formation and growth assays. To elucidate putative treatment options, identified via the molecular characterisation, PTEN pro- and deficient cells were treated with PI3K/mTOR/DNA-PK-inhibitor PI-103 or the ATM-inhibitors KU-60019 und AZD 1390. Changes in radiation sensitivity were assessed by colony-formation assay, FACS, western-blot, phospho-proteomic mass spectrometry and ex vivo lung slice cultures. ResultsWe 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. ConclusionPTEN 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.

cancer biology↗

bioRxiv2020

Inhibition of USP28 overcomes Cisplatin-Resistance of Squamous Tumors by Suppression of the Fanconi Anemia Pathway.

Squamous cell carcinomas (SCC) frequently have a limited response to or develop resistance to platinum-based chemotherapy, and have an exceptionally high tumor mutational burden. As a consequence, overall survival is limited and novel therapeutic strategies are urgently required, especially in light of a rising incidences. SCC tumors express {Delta}Np63, a potent regulator of the Fanconi Anemia (FA) DNA-damage response pathway during chemotherapy, thereby directly contributing to chemotherapy-resistance. Here we report that the deubiquitylase USP28 affects the FA DNA repair pathway during cisplatin treatment in SCC, thereby influencing therapy outcome. In an ATR-dependent fashion, USP28 is phosphorylated and activated to positively regulate the DNA damage response. Inhibition of USP28 reduces recombinational repair via an {Delta}Np63-Fanconi Anemia pathway axis, and weakens the ability of tumor cells to accurately repair DNA. Our study presents a novel mechanism by which tumor cells, and in particular {Delta}Np63 expressing SCC, can be targeted to overcome chemotherapy resistance. SignificanceLimited treatment options and low response rates to chemotherapy are particularly common in patients with squamous cancer. The SCC specific transcription factor {Delta}Np63 enhances the expression of Fanconi Anemia genes, thereby contributing to recombinational DNA repair and Cisplatin resistance. Targeting the USP28-{Delta}Np63 axis in SCC tones down this DNA damage response pathways, thereby sensitizing SCC cells to cisplatin treatment.

cancer biology↗