Checkpoint kinase 1 protein expression indicates sensitization to therapy by checkpoint kinase 1 inhibition in non–small cell lung cancer

Abstract

Background When presenting with advanced stage disease, lung cancer patients have <5% 5-y survival. The overexpression of checkpoint kinase 1 (CHK1) is associated with poorer outcomes and may contribute to therapy resistance. Targeting CHK1 with small-molecule inhibitors in p53 mutant tumors might improve the effectiveness of chemotherapy and radiotherapy in non–small cell lung cancer (NSCLC). Methods We evaluatedCHK1 messenger RNA and protein levels in multiple NSCLC cell lines. We assessed cell line sensitization to gemcitabine, pemetrexed, and radiotherapy by CHK1 inhibition with the small molecule AZD7762 using proliferation and clonogenic cell survival assays. We analyzed CHK1 signaling by Western blotting to confirm that AZD7762 inhibits CHK1. Results We selected two p53 mutant NSCLC cell lines with either high (H1299) or low (H1993) CHK1 levels for further analysis. We found that AZD7762 sensitized both cell lines to gemcitabine, pemetrexed, and radiotherapy. Chemosensitization levels were greater, however, for the higher CHK1 protein expressing cell line, H1299, when compared with H1993. Furthermore, analysis of the CHK1 signaling pathway showed that H1299 cells have an increased dependence on the CHK1 pathway in response to chemotherapy. There was no increased sensitization to radiation in H1299 versus H1993. Conclusions CHK1 inhibition by AZD7762 preferentially sensitizes high CHK1 expressing cells, H1299, to anti-metabolite chemotherapy as compared with low CHK1 expressing H1993 cells. Thus, CHK1 inhibitors may improve the efficacy of standard lung cancer therapies, especially for those subgroups of tumors harboring higher expression levels of CHK1 protein.

CHK1 Inhibition Radiosensitizes Head and Neck Cancers to Paclitaxel-Based Chemoradiotherapy

“…Certainly, HN5 cells exhibited greater activation of CHK1 following irradiation compared with HN4 cells. This correlates with findings from two recent studies carried out in non-small cell lung cancer where CHK1 levels and activity indicated sensitivity to CHK1-targeted therapy (33,34). Likewise, we hypothesized that high CHK1 activity could be a marker of radiation resistance and may serve as a biomarker for tumors likely to relapse and, thus, identify the patients who would benefit the most from triple therapy.…”

Family-wide Structural Analysis of Human Numb-Associated Protein Kinases

“…Baricitinib has been reported to be a potent and selective inhibitor of JAK1/2, and is currently being tested in phase III clinical trials for the treatment of rheumatoid arthritis ( Norman, 2014 , Shi et al., 2014 , van Vollenhoven, 2013 ). The small molecule AZD7762, an inhibitor of the checkpoint kinases CHEK1 and CHEK2, potentiates anti-tumor activity in pre-clinical studies of various cancers when co-administered with other DNA-damage agents ( Ashwell et al., 2008 , Grabauskiene et al., 2014 , Landau et al., 2012 , Morgan et al., 2010 , Zabludoff et al., 2008 ). Both inhibitors are ATP-competitive, forming two H-bonding interactions with the backbone of the hinge at residues E131 and C133.…”

DNA Damage Signalling and Repair Inhibitors: The Long-Sought-After Achilles’ Heel of Cancer

“…Recently, Sarmento et al have shown that Chk1 overexpression in T-cell acute lymphoblastic leukemia (T-ALL) enables cellular proliferation and survival by preventing replication stress [ 88 ]. Chk1 overexpression contributes to cancer resistance by delaying mitotic entry and thereby it has been associated with tumour grade and poor prognosis [ 89 , 90 ]. Chk1 contributes to cell survival by inducing G2 arrest and signalling to the HR pathway for DNA repair [ 82 ].…”

“…It has been described that lung cancer cells expressing high levels of Chk1 were hypersensitive to AZD7762. This suggests a correlation between Chk1 inhibitor-mediated sensitivity and elevated amounts of Chk1 [ 89 ]. In one report, the combination of AZD7762 with gemcitabine and ionizing radiation was assessed in vitro and allowed sensitizing pancreatic cells to radiation.…”