Genome-wide siRNA Screen Identifies the Radiosensitizing Effect of Downregulation of MASTL and FOXM1 in NSCLC

Abstract

Lung cancer is the most common cancer worldwide and on top of that has a very poor prognosis, which is reflected by a 5-year survival rate of 5% to 15%. Radiotherapy is an integral part of most treatment regimens for this type of tumor, often combined with radiosensitizing cytotoxic drugs. In this study, we identified many genes that could potentially be exploited for targeted radiosensitization using a genome-wide siRNA screen in non-small cell lung cancer (NSCLC) cells. The screen identified 433 siRNAs that potentially sensitize lung cancer cells to radiation. Validation experiments showed that knockdown of expression of Forkhead box M1 (FOXM1) or microtubuleassociated serine/threonine kinase-like (MASTL) indeed causes radiosensitization in a panel of NSCLC cells. Strikingly, this effect was not observed in primary human fibroblasts, suggesting that the observed radiosensitization is specific for cancer cells. Phosphoproteomics analyses with and without irradiation showed that a number of cell-cycle-related proteins were significantly less phosphorylated after MASTL knockdown in comparison to the control, while there were no changes in the levels of phosphorylation of DNA damage response proteins. Subsequent analyses showed that MASTL knockdown cells respond differently to radiation, with a significantly shortened G 2 -M phase arrest and defects in cytokinesis, which are followed by a cell-cycle arrest. In summary, we have identified many potential therapeutic targets that could be used for radiosensitization of NSCLC cells, with MASTL being a very promising and druggable target to combine with radiotherapy.

Greatwall kinase at a glance

“…Recent evidence from a variety of model systems has shown that, besides its primordial role in mitotic division, Gwl also contributes in a significant extent to tumorigenic processes (Alvarez-Fernandez et al, 2017;Uppada et al, 2018;Vera et al, 2015;Dahlhaus et al, 2016;Nagel et al, 2015). Upregulation of Gwl activity promotes cell transformation and increases cell proliferation in several immortalized cells lines and in primary human fibroblasts (Vera et al, 2015).…”

MASTL promotes cell contractility and motility through kinase-independent signaling

“…In breast cancer, MASTL expression increases with advanced clinical stage and predicts poor survival (Álvarez-Fernández et al, 2018;Rogers et al, 2018;Wang et al, 2016;Yoon et al, 2018), with high MASTL levels positively correlating with increased tumor growth and metastasis in vivo (Álvarez-Fernández et al, 2018;Rogers et al, 2018;Vera et al, 2015). Moreover, knockdown of MASTL induces radiosensitivity (Nagel et al, 2015), which makes MASTL an appealing pharmacological target. However, the exact mechanism of how MASTL facilitates tumorigenicity remains unknown.…”

Tanshinone IIA combined with adriamycin inhibited malignant biological behaviors of NSCLC A549 cell line in a synergistic way

“…Lung cancer is a leading cause of cancer death worldwide, with a 5-year survival rate of 5–15% [1]. Non-small cell lung cancer (NSCLC), accounting for approximately 85% of all lung cancer cases, is the dominant type.…”