Biology subjects

Zhang, S. M.

Publications and source records attributed to Zhang, S. M..

3 recordsLinked to original sources

bioRxiv2020

Drug synergy scoring using minimal dose response matrices

ObjectiveCombinations of pharmacological agents are essential for disease control and prevention, offering many advantages over monotherapies, with one of these being drug synergy. The state-of-the-art method to profile drug synergy in preclinical research is by using dose-response matrices in disease-appropriate models, however this approach is frequently labour intensive and cost-ineffective, particularly when performed in a medium- to high-throughput fashion. Thus, in this study, we set out to optimise a parameter of this methodology, determining the minimal matrix size that can be used to robustly detect and quantify synergy between two drugs. ResultsWe used a drug matrix reduction workflow that allowed the identification of a minimal drug matrix capable of robustly detecting and quantifying drug synergy. These minimal matrices utilise substantially less reagents and data processing power than their typically used larger counterparts. Focusing on the antileukemic efficacy of the chemotherapy combination of cytarabine and inhibitors of ribonucleotide reductase, we could show that detection and quantification of drug synergy by three common synergy models was well-tolerated despite reducing matrix size from 8x8 to 4x4. Overall, the optimisation of drug synergy scoring as presented here could inform future medium- to high-throughput drug synergy screening strategies in pre-clinical research. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/362103v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@fd5e27org.highwire.dtl.DTLVardef@30570dorg.highwire.dtl.DTLVardef@1a33039org.highwire.dtl.DTLVardef@b2f00c_HPS_FORMAT_FIGEXP M_FIG C_FIG

pharmacology and toxicology↗

bioRxiv2020

A Multi-pronged Screening Approach Targeting Inhibition of ETV6 PNT Domain Polymerization

ETV6 is an ETS family transcriptional repressor for which head-to-tail polymerization of its PNT domain facilitates cooperative binding to DNA by its ETS domain. Chromosomal translocations frequently fuse the ETV6 PNT domain to one of several protein tyrosine kinases. The resulting chimeric oncoproteins undergo ligand-independent self-association, autophosphorylation, and aberrant stimulation of downstream signaling pathways leading to a variety of cancers. Currently, no small molecules inhibitors of ETV6 PNT domain polymerization are known and no assays targeting PNT domain polymerization have been described. In this study, we developed complementary experimental and computational approaches for identifying such inhibitory compounds. One mammalian cellular approach utilized a mutant PNT domain heterodimer system covalently attached to split Gaussia luciferase fragments. In this protein fragment complementation assay, inhibition of PNT domain heterodimerization reduces luminescence. A yeast assay took advantage of activation of the reporter HIS3 gene upon heterodimerization of mutant PNT domains fused to DNA-binding and transactivation domains. In this two-hybrid screen, inhibition of PNT domain heterodimerization prevents cell growth in medium lacking histidine. The Bristol University Docking Engine (BUDE) was used to identify virtual ligands from the ZINC8 library predicted to bind the PNT domain polymerization interfaces. Over 75 hits from these three assays were tested by NMR spectroscopy for binding to the purified ETV6 PNT domain. Although none were found to bind, lessons learned from this study may facilitate future approaches for developing therapeutics that act against ETV6 oncoproteins by disrupting PNT domain polymerization.

biochemistry↗

bioRxiv2020

SAMHD1 promotes oncogene-induced replication stress

Oncogenes induce DNA replication stress in cancer cells. Although this was established more than a decade ago, we are still unravelling the molecular underpinnings of this phenomenon, which will be critical if we are to exploit this knowledge to improve cancer treatment. A key mediator of oncogene-induced replication stress is the availability of DNA precursors, which will limit ongoing DNA synthesis by cellular replicases. In this study, we identify a potential role for nucleotide catabolism in promoting replication stress induced by oncogenes. Specifically, we establish that the dNTPase SAMHD1 slows DNA replication fork speeds in human fibroblasts harbouring an oncogenic RAS allele, elevating levels of endogenous DNA damage, and ultimately limiting cell proliferation. We then show that oncogenic RAS-driven tumours express reduced SAMHD1 levels, suggesting they have overcome this tumour suppressor barrier, and that this correlates with worse overall survival for these patients. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=76 SRC="FIGDIR/small/226282v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@bb425forg.highwire.dtl.DTLVardef@2a1b7org.highwire.dtl.DTLVardef@c70bf3org.highwire.dtl.DTLVardef@1e1b028_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗