8 research outputs found
Inactivation of the Saccharomyces cerevisiae SKY1 gene induces a specific modification of the yeast anticancer drug sensitivity profile accompanied by a mutator phenotype
The therapeutic potential of the highly active anticancer agent cisplatin
is severely limited by the occurrence of cellular resistance. A better
understanding of the molecular pathways involved in cisplatin-induced cell
death could potentially indicate ways to overcome cellular
unresponsiveness to the drug and thus lead to better treatment results. We
used the budding yeast Saccharomyces cerevisiae as a model organism to
identify and characterize novel genes involved in cisplatin-induced cell
kill, and found that SKY1 (SR-protein-specific kinase from budding yeast)
is a cisplatin sensitivity gene whose disruption conferred cisplatin
resistance. In cross-resistance studies, we observed resistance of yeast
sky1 Delta cells (i.e., cells from which the SKY1 gene had been disrupted)
to cisplatin, carboplatin (but not oxaliplatin), doxorubicin and
daunorubicin, and hypersensitivity to cadmium chloride and 5-fluorouracil.
Furthermore, these cells did not display reduced platinum accumulation,
DNA platination or doxorubicin accumulation, indicating that the
resistance is unrelated to decreased drug import or increased drug export.
Based on the modification of the anticancer drug sensitivity profile and
our finding that sky1 Delta cells display a mutator phenotype, we propose
that Sky1p might play a significant role in specific repair and/or
tolerance pathways. Disruption of the S. cerevisiae SKY1 gene would thus
result in deregulation of such mechanisms and, consequently, lead to
altered drug sensitivity
Imatinib mesylate (STI571) is a substrate for the breast cancer resistance protein (BCRP)/ABCG2 drug pump
Imatinib mesylate (STI571), a potent tyrosine kinase inhibitor, is
successfully used in the treatment of chronic myelogenous leukemia and
gastrointestinal stromal tumors. However, the intended chronic oral
administration of imatinib may lead to development of cellular resistance
and subsequent treatment failure. Indeed, several molecular mechanisms
leading to imatinib resistance have already been reported, including
overexpression of the MDR1/ABCB1 drug pump. We examined whether imatinib
is a substrate for the breast cancer resistance protein (BCRP)/ABCG2 drug
pump that is frequently overexpressed in human tumors. Using a panel of
well-defined BCRP-overexpressing cell lines, we provide the first evidence
that imatinib is a substrate for BCRP, that it competes with mitoxantrone
for drug export, and that BCRP-mediated efflux can be reversed by the
fumitremorgin C analog Ko-143. Since BCRP is highly expressed in the
gastrointestinal tract, BCRP might not only play a role in cellular
resistance of tumor cells but also influence the gastrointestinal
absorption of imatinib
Mesenchymal tumor organoid models recapitulate rhabdomyosarcoma subtypes
Rhabdomyosarcomas (RMS) are mesenchyme-derived tumors and the most common childhood soft tissue sarcomas. Treatment is intense, with a nevertheless poor prognosis for high-risk patients. Discovery of new therapies would benefit from additional preclinical models. Here, we describe the generation of a collection of 19 pediatric RMS tumor organoid (tumoroid) models (success rate of 41%) comprising all major subtypes. For aggressive tumors, tumoroid models can often be established within 4-8âweeks, indicating the feasibility of personalized drug screening. Molecular, genetic, and histological characterization show that the models closely resemble the original tumors, with genetic stability over extended culture periods of up to 6âmonths. Importantly, drug screening reflects established sensitivities and the models can be modified by CRISPR/Cas9 with TP53 knockout in an embryonal RMS model resulting in replicative stress drug sensitivity. Tumors of mesenchymal origin can therefore be used to generate organoid models, relevant for a variety of preclinical and clinical research questions
Mesenchymal tumor organoid models recapitulate rhabdomyosarcoma subtypes
Rhabdomyosarcomas (RMS) are mesenchyme-derived tumors and the most common childhood soft tissue sarcomas. Treatment is intense, with a nevertheless poor prognosis for high-risk patients. Discovery of new therapies would benefit from additional preclinical models. Here, we describe the generation of a collection of 19 pediatric RMS tumor organoid (tumoroid) models (success rate of 41%) comprising all major subtypes. For aggressive tumors, tumoroid models can often be established within 4â8 weeks, indicating the feasibility of personalized drug screening. Molecular, genetic, and histological characterization show that the models closely resemble the original tumors, with genetic stability over extended culture periods of up to 6 months. Importantly, drug screening reflects established sensitivities and the models can be modified by CRISPR/Cas9 with TP53 knockout in an embryonal RMS model resulting in replicative stress drug sensitivity. Tumors of mesenchymal origin can therefore be used to generate organoid models, relevant for a variety of preclinical and clinical research questions
Genomeâwide offârates reveal how DNA binding dynamics shape transcription factor function
Abstract ProteinâDNA interactions are dynamic, and these dynamics are an important aspect of chromatinâassociated processes such as transcription or replication. Due to a lack of methods to study onâ and offârates across entire genomes, proteinâDNA interaction dynamics have not been studied extensively. Here, we determine in vivo offârates for the Saccharomyces cerevisiae chromatin organizing factor Abf1, at 191 sites simultaneously across the yeast genome. Average Abf1 residence times span a wide range, varying between 4.2 and 33 min. Sites with different offârates are associated with different functional characteristics. This includes their transcriptional dependency on Abf1, nucleosome positioning and the size of the nucleosomeâfree region, as well as the ability to roadblock RNA polymerase II for termination. The results show how offârates contribute to transcription factor function and that DIVORSEQ (Determining In Vivo OffâRates by SEQuencing) is a meaningful way of investigating proteinâDNA binding dynamics genomeâwide