Identification of Novel Cdc7 Kinase Inhibitors as Anti-Cancer Agents that Target the Interaction with Dbf4 by the Fragment Complementation and Drug Repositioning Approach

Abstract

BackgroundCdc7-Dbf4 is a conserved serine/threonine kinase that plays an important role in initiation of DNA replication and DNA damage tolerance in eukaryotic cells. Cdc7 has been found overexpressed in human cancer cell lines and tumor tissues, and the knockdown of Cdc7 expression causes an p53-independent apoptosis, suggesting that Cdc7 is a target for cancer therapy. Only a handful Cdc7 kinase inhibitors have been reported. All Cdc7 kinase inhibitors, including PHA-767491, were identified and characterized as ATP-competitive inhibitors. Unfortunately, these ATP-competitive Cdc7 inhibitors have no good effect on clinical trial.MethodsHere, we have developed a novel drug-screening platform to interrupt the interaction between Cdc7 and Dbf4 based on Renilla reniformis luciferase (Rluc)-linked protein-fragment complementation assay (Rluc-PCA). Using drug repositioning approach, we found several promising Cdc7 inhibitors for cancer therapy from a FDA-approved drug library.FindingsOur data showed that dequalinium chloride and clofoctol we screened inhibit S phase progression, accumulation in G2/M phase, and Cdc7 kinase activity. In addition, in vivo mice animal study suggests that dequalinium chloride has a promising anti-tumor activity in oral cancer. Interestingly, we also found that dequalinium chloride and clofoctol sensitize the effect of platinum compounds and radiation due to synergistic effect. In conclusion, we identified non-ATP-competitive Cdc7 kinase inhibitors that not only blocks DNA synthesis at the beginning but also sensitizes cancer cells to DNA damage agents.InterpretationThe inhibitors will be a promising anti-cancer agent and enhance the therapeutic effect of chemotherapy and radiation for current cancer therapy.FundThis work was supported by grants from the Ministry of Science and Technology, Ministry of Health and Welfare, and National Health Research Institutes, Taiwan.

Antiplatelet Drug Ticagrelor Enhances Chemotherapeutic Efficacy by Targeting the Novel P2Y12-AKT Pathway in Pancreatic Cancer Cells

“…Furthermore, our results showing minimal impact of ticagrelor on normal pancreatic duct cells were comparable to the previous Food and Drug Administration (FDA) data indicating ticagrelor up to 20 µM had a negligible toxicity on hepatocytes in vitro [33]. Ticagrelor has been reported to have several off-target effects that may be related to tumour growth [33,49,51,52]. Therefore, it is possible that the anticancer activity of ticagrelor is the result of a multitarget effect.…”

Structural Basis for the Activation and Target Site Specificity of CDC7 Kinase

“…CDC7 and DBF4 tend to be overexpressed in primary cancers and tumor cell lines, and their levels negatively correlate with patient prognosis ( Bonte et al., 2008 , Cheng et al., 2013 , Clarke et al., 2009 , Ghatalia et al., 2016 , Hou et al., 2012 , Jaafari-Ashkavandi et al., 2019 , Kulkarni et al., 2009 , Melling et al., 2015 , Subramanian and Cohen, 2019 , Zhuang et al., 2018 ). Selective inhibition of CDC7 suppresses proliferation of transformed cells through induction of S-phase delay and replication stress ( Cheng et al., 2018 , Im and Lee, 2008 , Ito et al., 2012 , Iwai et al., 2019 , Montagnoli et al., 2004 ). Furthermore, CDC7 antagonists showed promise in combination with other cell-cycle inhibitors and anti-cancer therapeutics ( Cao and Lu, 2019 , Gad et al., 2019 , O' Reilly et al., 2018 ).…”

“…Furthermore, CDC7 antagonists showed promise in combination with other cell-cycle inhibitors and anti-cancer therapeutics ( Cao and Lu, 2019 , Gad et al., 2019 , O' Reilly et al., 2018 ). Selective inhibitors of CDC7 are being developed and trialed as anti-cancer therapeutics, with a number of candidate drugs undergoing clinical trials ( Cheng et al., 2018 , Gallagher et al., 2019 , Huggett et al., 2016 , Iwai et al., 2019 , Koltun et al., 2012 , Kurasawa et al., 2020 , Sawa and Masai, 2009 , Swords et al., 2010 , Vanotti et al., 2008 ). The efforts to develop small-molecule inhibitors will greatly benefit from high-resolution structural information.…”

Biophysical Techniques for Target Validation and Drug Discovery in Transcription-Targeted Therapy

“…BiFC and BiLC have been used to detect PPIs in a variety of organisms, from yeast [91] to plants [92]. Both techniques have been instrumental in detecting and targeting membrane proteins, in particular G-protein coupled receptors (GPCRs) [93,94] as well as have successfully guided the identification of new antiviral [95] and anticancer [96] molecules. Many groups have explored the interactions of transcription factors with other proteins as well as with DNA using different versions of PCAs [97][98][99][100][101].…”