Biology subjects

Krystof, V.

Publications and source records attributed to Krystof, V..

3 recordsLinked to original sources

bioRxiv2023

Characterization of new highly selective pyrazolopyrimidine inhibitor of CDK7

Targeting cyclin-dependent kinase 7 (CDK7) provides an interesting therapeutic option in cancer therapy because this kinase participates in regulating the cell cycle and transcription. Here, we describe a new trisubstituted pyrazolo[4,3-d]pyrimidine derivative, LGR6768, that inhibits CDK7 in the nanomolar range and displays favourable selectivity across the CDK family. We determined the structure of fully active CDK2/cyclin A2 in complex with LGR6768 at 2.6 [A] resolution using X-ray crystallography, revealing conserved interactions within the active site. Structural analysis and comparison with LGR6768 docked to CDK7 provides an explanation of the observed biochemical selectivity, which is linked to a conformational difference in the biphenyl moiety. In cellular experiments, LGR6768 affected regulation of the cell cycle and transcription by inhibiting the phosphorylation of cell cycle CDKs and the carboxy-terminal domain of RNA polymerase II, respectively. LGR6768 limited the proliferation of several leukaemia cell lines, triggered significant changes in protein and mRNA levels related to CDK7 inhibition and induced apoptosis in dose- and time-dependent experiments. Our work supports previous findings and provides further information for the development of selective CDK7 inhibitors. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=58 SRC="FIGDIR/small/529844v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1d13e99org.highwire.dtl.DTLVardef@64ea36org.highwire.dtl.DTLVardef@14c9705org.highwire.dtl.DTLVardef@14efc31_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Anticancer effect of zanubrutinib in HER2-positive breast cancer cell lines

Small molecule Brutons tyrosine kinase (BTK) inhibitors have been developed for the treatment of various haemato-oncological diseases, and ibrutinib was approved as the first BTK inhibitors for anticancer therapy in 2013. Previous reports proved the receptor kinase human epidermal growth factor receptor 2 (HER2) to be a valid off-target kinase of ibrutinib and potentially other irreversible BTK inhibitors, as it possesses a druggable cysteine residue in the active site of the enzyme. These findings suggest ibrutinib as a candidate drug for repositioning in HER2-positive breast cancer (BCa). This subtype of breast cancer belongs to one of the most common classes of breast tumours, and its prognosis is characterized by a high rate of recurrence and tumour invasiveness. Based on their similar kinase selectivity profiles, we investigated the anticancer effect of zanubrutinib, evobrutinib, tirabrutinib and acalabrutinib in different BCa cell lines and sought to determine whether it is linked with targeting the epidermal growth factor receptor family (ERBB) pathway. We found that zanubrutinib is a potential inhibitor of the HER2 signalling pathway, displaying an antiproliferative effect in HER2-positive BCa cell lines. Zanubrutinib effectively inhibits the phosphorylation of proteins in the ERBB signalling cascade, including the downstream kinases Akt and ERK, which mediate key signals ensuring the survival and proliferation of cancer cells. We thus propose zanubrutinib as another suitable candidate for repurposing in HER2-amplified solid tumours.

cancer biology↗

bioRxiv2022

Synthesis and structural optimization of 2,7,9-trisubstituted purin-8-ones as FLT3-ITD inhibitors

Therapy of FLT3-positive acute myeloid leukemia still remains complicated, despite the availability of newly approved kinase inhibitors. Various strategies to avoid reduced efficacy of therapy are explored including the development of dual targeting compounds, which inhibit FLT3 and another kinase necessary for survival and proliferation of AML cells. We have designed new 2,7,9-trisubstituted 8-oxopurines as FLT3 inhibitors and report here structure-activity relationship studies. We demonstrated that substituents at positions 7 and 9 modulate activity between CDK4 and FLT3 kinase and the isopropyl group at position 7 increased substantially the selectivity toward FLT3 kinase, which led to the discovery of compound 15a (9-cyclopentyl-7-isopropyl-2-((4-(piper-azin-1-yl)phenyl)amino)-7,9-dihydro-8H-purin-8-one). Cellular analyses in MV4-11 cells revealed inhibition of autophosphorylation of FLT3 kinase in nanomolar doses including suppression of downstream STAT5 and ERK1/2 phosphorylation. We also describe mechanistic studies in cell lines and activity in a mouse xenograft model in vivo.

pharmacology and toxicology↗