TNIK inhibition sensitizes TNIK-overexpressing lung squamous cell carcinoma to radiotherapy.

Most patients with lung squamous cell carcinoma (LSCC) undergo chemotherapy, radiotherapy, and adjuvant immunotherapy for locally advanced disease. The efficacy of these treatments is still limited due to dose-limiting toxicity or locoregional recurrence. New combination approaches and targets such as actionable oncogenic drivers are needed to advance treatment options for LSCC patients. Moreover, other options for chemotherapy-ineligible patients are also limited. As such there is a critical need for the development of selective and potent chemoradiosensitizers for locally advanced LSCC. Here, we investigated inhibiting TRAF2 and NCK-interacting protein kinase (TNIK), which is amplified in 40% of LSCC patients, as a strategy to sensitize LSCC tumors to chemo- and radiotherapy. Employing a range of human LSCC cell lines and the TNIK inhibitor NCB-0846, we investigated the potential of TNIK as a chemo- and radiosensitizing target with in vitro and in vivo preclinical models. The combination of NCB-0846 with cisplatin or etoposide was at best additive. Interestingly, pre-treating LSCC cells with NCB-0846 prior to ionizing radiation (IR) potentiated the cytotoxicity of IR in a TNIK-specific fashion. Characterization of the radiosensitization mechanism suggested that TNIK inhibition may impair the DNA damage response and promote mitotic catastrophe in irradiated cells. In a subcutaneous xenograft in vivo model, pretreatment with NCB-0846 significantly enhanced the efficacy of IR and caused elevated necrosis in TNIKhigh LK2 tumors but not TNIKlow KNS62 tumors. Overall, these results indicate that TNIK inhibition may be a promising strategy to increase the efficacy of radiotherapy in LSCC patients with high TNIK expression.

Griseofulvin Radiosensitizes Non-Small Cell Lung Cancer Cells and Activates cGAS.

Extra copies of centrosomes are frequently observed in cancer cells. To survive and proliferate, cancer cells have developed strategies to cluster extra-centrosomes to form bipolar mitotic spindles. The aim of this study was to investigate whether centrosome clustering (CC) inhibition (CCi) would preferentially radiosensitize non-small cell lung cancer (NSCLC). Griseofulvin (GF; FDA-approved treatment) inhibits CC, and combined with radiation treatment (RT), resulted in a significant increase in the number of NSCLC cells with multipolar spindles, and decreased cell viability and colony formation ability in vitro. In vivo, GF treatment was well tolerated by mice, and the combined therapy of GF and radiation treatment resulted in a significant tumor growth delay. Both GF and radiation treatment also induced the generation of micronuclei (MN) in vitro and in vivo and activated cyclic GMP-AMP synthase (cGAS) in NSCLC cells. A significant increase in downstream cGAS-STING pathway activation was seen after combination treatment in A549 radioresistant cells that was dependent on cGAS. In conclusion, GF increased radiation treatment efficacy in lung cancer preclinical models in vitro and in vivo. This effect may be associated with the generation of MN and the activation of cGAS. These data suggest that the combination therapy of CCi, radiation treatment, and immunotherapy could be a promising strategy to treat NSCLC.

CDK1 and CDK2 regulate NICD1 turnover and the periodicity of the segmentation clock.

All vertebrates share a segmented body axis. Segments form from the rostral end of the presomitic mesoderm (PSM) with a periodicity that is regulated by the segmentation clock. The segmentation clock is a molecular oscillator that exhibits dynamic clock gene expression across the PSM with a periodicity that matches somite formation. Notch signalling is crucial to this process. Altering Notch intracellular domain (NICD) stability affects both the clock period and somite size. However, the mechanism by which NICD stability is regulated in this context is unclear. We identified a highly conserved site crucial for NICD recognition by the SCF E3 ligase, which targets NICD for degradation. We demonstrate both CDK1 and CDK2 can phosphorylate NICD in the domain where this crucial residue lies and that NICD levels vary in a cell cycle-dependent manner. Inhibiting CDK1 or CDK2 activity increases NICD levels both in vitro and in vivo, leading to a delay of clock gene oscillations and an increase in somite size.