Dataset Information

Radiosensitization of HNSCC cells by EGFR inhibition depends on the induction of cell cycle arrests.

ABSTRACT: The increase in cellular radiosensitivity by EGF receptor (EGFR) inhibition has been shown to be attributable to the induction of a G1-arrest in p53-proficient cells. Because EGFR targeting in combination with radiotherapy is used to treat head and neck squamous cell carcinomas (HNSCC) which are predominantly p53 mutated, we tested the effects of EGFR targeting on cellular radiosensitivity, proliferation, apoptosis, DNA repair and cell cycle control using a large panel of HNSCC cell lines. In these experiments EGFR targeting inhibited signal transduction, blocked proliferation and induced radiosensitization but only in some cell lines and only under normal (pre-plating) conditions. This sensitization was not associated with impaired DNA repair (53BP1 foci) or induction of apoptosis. However, it was associated with the induction of a lasting G2-arrest. Both, the radiosensitization and the G2-arrest were abrogated if the cells were re-stimulated (delayed plating) with actually no radiosensitization being detectable in any of the 14 tested cell lines. Therefore we conclude that EGFR targeting can induce a reversible G2 arrest in p53 deficient HNSCC cells, which does not consequently result in a robust cellular radiosensitization. Together with recent animal and clinical studies our data indicate that EGFR inhibition is no effective strategy to increase the radiosensitivity of HNSCC cells.

SUBMITTER: Kriegs M

PROVIDER: S-EPMC5216710 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Radiosensitization of HNSCC cells by EGFR inhibition depends on the induction of cell cycle arrests.

Kriegs Malte M Kasten-Pisula Ulla U Riepen Britta B Hoffer Konstantin K Struve Nina N Myllynen Laura L Braig Friederike F Binder Mascha M Rieckmann Thorsten T Grénman Reidar R Petersen Cordula C Dikomey Ekkehard E Rothkamm Kai K

Oncotarget 20160701 29

The increase in cellular radiosensitivity by EGF receptor (EGFR) inhibition has been shown to be attributable to the induction of a G1-arrest in p53-proficient cells. Because EGFR targeting in combination with radiotherapy is used to treat head and neck squamous cell carcinomas (HNSCC) which are predominantly p53 mutated, we tested the effects of EGFR targeting on cellular radiosensitivity, proliferation, apoptosis, DNA repair and cell cycle control using a large panel of HNSCC cell lines. In th ...[more]

PMID: 27281611

Similar Datasets

Project description:In head and neck squamous cell carcinoma (HNSCC), tumors positive for human papillomavirus (HPV) represent a distinct biological entity with favorable prognosis. An enhanced radiation sensitivity of these tumors is evident in the clinic and on the cellular level when comparing HPV-positive and HPV-negative HNSCC cell lines. We could show that the underlying mechanism is a defect in DNA double-strand break repair associated with a profound and sustained G2 arrest. This defect can be exploited by molecular targeting approaches additionally compromising the DNA damage response to further enhance their radiation sensitivity, which may offer new opportunities in the setting of future de-intensified regimes. Against this background, we tested combined targeting of PARP and the DNA damage-induced intra-S/G2 cell cycle checkpoints to achieve effective radiosensitization. Enhancing CDK1/2 activity through the Wee1 inhibitor adavosertib or a combination of Wee1 and Chk1 inhibition resulted in an abrogation of the radiation-induced G2 cell cycle arrest and induction of replication stress as assessed by γH2AX and chromatin-bound RPA levels in S phase cells. Addition of the PARP inhibitor olaparib had little influence on these endpoints, irrespective of checkpoint inhibition. Combined PARP/Wee1 targeting did not result in an enhancement in the absolute number of residual, radiation induced 53BP1 foci as markers of DNA double-strand breaks but it induced a shift in foci numbers from S/G2 to G1 phase cells. Most importantly, while sole checkpoint or PARP inhibition induced moderate radiosensitization, their combination was clearly more effective, while exerting little effect in p53/G1 arrest proficient normal human fibroblasts, thus indicating tumor specificity. We conclude that the combined inhibition of PARP and the intra-S/G2 checkpoint is a highly effective approach for the radiosensitization of HPV-positive HNSCC cells and may represent a viable alternative for the current standard of concomitant cisplatin-based chemotherapy. In vivo studies to further evaluate the translational potential are highly warranted.

Project description:BackgroundFocal adhesion signaling involving receptor tyrosine kinases (RTK) and integrins co-controls cancer cell survival and therapy resistance. However, co-dependencies between these receptors and therapeutically exploitable vulnerabilities remain largely elusive in HPV-negative head and neck squamous cell carcinoma (HNSCC).MethodsThe cytotoxic and radiochemosensitizing potential of targeting 10 RTK and β1 integrin was determined in up to 20 3D matrix-grown HNSCC cell models followed by drug screening and patient-derived organoid validation. RNA sequencing and protein-based biochemical assays were performed for molecular characterization. Bioinformatically identified transcriptomic signatures were applied to patient cohorts.ResultsFibroblast growth factor receptor (FGFR 1-4) targeting exhibited the strongest cytotoxic and radiosensitizing effects as monotherapy and combined with β1 integrin inhibition, exceeding the efficacy of the other RTK studied. Pharmacological pan-FGFR inhibition elicited responses ranging from cytotoxicity/radiochemosensitization to resistance/radiation protection. RNA sequence analysis revealed a mesenchymal-to-epithelial transition (MET) in sensitive cell models, whereas resistant cell models exhibited a partial epithelial-to-mesenchymal transition (EMT). Accordingly, inhibition of EMT-associated kinases such as EGFR caused reduced adaptive resistance and enhanced (radio)sensitization to FGFR inhibition cell model- and organoid-dependently. Transferring the EMT-associated transcriptomic profiles to HNSCC patient cohorts not only demonstrated their prognostic value but also provided a conclusive validation of the presence of EGFR-related vulnerabilities that can be strategically exploited for therapeutic interventions.ConclusionsThis study demonstrates that pan-FGFR inhibition elicits a beneficial radiochemosensitizing and a detrimental radioprotective potential in HNSCC cell models. Adaptive EMT-associated resistance appears to be of clinical importance, and we provide effective molecular approaches to exploit this therapeutically.

Dataset Information

Radiosensitization of HNSCC cells by EGFR inhibition depends on the induction of cell cycle arrests.

Publications

Radiosensitization of HNSCC cells by EGFR inhibition depends on the induction of cell cycle arrests.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets