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Biology subjects

Miettinen, S.

Publications and source records attributed to Miettinen, S..

2 recordsLinked to original sources

Designing patient-oriented combination therapies for acute myeloid leukemia based on efficacy/toxicity integration and bipartite network modeling

Acute myeloid leukemia (AML), a heterogeneous and aggressive blood cancer, does not respond well to single-drug therapy. A combination of drugs is required to effectively treat this disease. Computational models are critical for combination therapy discovery due to the tens of thousands of two-drug combinations, even with approved drugs. While predicting synergistic drugs is the focus of current methods, few consider drug efficacy and potential toxicity, which are crucial for treatment success. To find effective new drug candidates, we constructed a bipartite network using patient-derived tumor samples and drugs. The network is based on drug-response screening and summarizes all treatment response heterogeneity as drug response weights. This bipartite network is then projected onto the drug part, resulting in the drug similarity network. Distinct drug clusters were identified using community detection methods, each targeting different biological processes and pathways as revealed by enrichment and pathway analysis of the drugs protein targets. Four drugs with the highest efficacy and lowest toxicity from each cluster were selected and tested for drug sensitivity using cell viability assays on various samples. Results show that the combinations of ruxolitinib-ulixertinib and sapanisertib-LY3009120 are the most effective with the least toxicity and best synergistic effects on blasts. These findings lay the foundation for personalized and successful AML therapies, ultimately leading to the development of drug combinations that can be used alongside standard first-line AML treatment. Key PointsO_LIRuxolitinib-ulixertinib and sapanisertib-LY3009120 have the best synergistic effects on AML, with the least toxicity. C_LIO_LIThis studys combinations destroy blasts without harming other healthy cells, unlike standard chemotherapy, which is less specific. C_LI

cancer biology↗

A second hybrid-binding domain modulates the activity of Drosophila ribonuclease H1

In eukaryotes, ribonuclease H1 (RNase H1) is involved in the processing and removal of RNA/DNA hybrids in both nuclear and mitochondrial DNA. The enzyme comprises a C-terminal catalytic domain and an N-terminal hybrid-binding domain (HBD), separated by a linker of variable length, which in Drosophila melanogaster (Dm) is exceptionally long, 115 amino acids. Molecular modeling predicted this extended linker to fold into a structure similar to the conserved HBD. We measured catalytic activity and substrate binding by EMSA and biolayer interferometry, using a deletion series of protein variants. Both the catalytic domain and the conserved HBD were required for high-affinity binding to heteroduplex substrates, whilst loss of the novel HBD led to a [~]90% drop in K[cat] with a decreased K[M], and a large increase in the stability of the RNA/DNA hybrid-enzyme complex. The findings support a bipartite binding model for the enzyme, whereby the second HBD facilitates dissociation of the active site from the product, allowing for processivity. We used shotgun proteomics to identify protein partners of the enzyme involved in mediating these effects. Single-stranded DNA-binding proteins from both the nuclear and mitochondrial compartments, respectively RpA-70 and mtSSB, were prominently detected by this method. However, we were not able to document direct interactions between mtSSB and Dm RNase H1 when co-overexpressed in S2 cells, or functional interactions in vitro. Further studies are needed to determine the exact reaction mechanism of Dm RNase H1, the nature of its interaction with mtSSB and the role of the second HBD in both.

molecular biology↗