Single-cell transcriptional changes associated with drug tolerance and response to combination therapies in cancer

Tyrosine kinase inhibitors were found to be clinically effective for treatment of patients with certain subsets of cancers carrying somatic mutations in receptor tyrosine kinases. However, the duration of clinical response is often limited, and patients ultimately develop drug resistance. Here, we use single-cell RNA sequencing to demonstrate the existence of multiple cancer cell subpopulations within cell lines, xenograft tumors and patient tumors. These subpopulations exhibit epigenetic changes and differential therapeutic sensitivity. Recurrently overrepresented ontologies in genes that are differentially expressed between drug tolerant cell populations and drug sensitive cells include epithelial-to-mesenchymal transition, epithelium development, vesicle mediated transport, drug metabolism and cholesterol homeostasis. We show analysis of identified markers using the LINCS database to predict and functionally validate small molecules that target selected drug tolerant cell populations. In combination with EGFR inhibitors, crizotinib inhibits the emergence of a defined subset of EGFR inhibitor-tolerant clones. In this study, we describe the spectrum of changes associated with drug tolerance and inhibition of specific tolerant cell subpopulations with combination agents.

Protein status of winter wheat cell lines with combined tolerace to abiotic stresses

Aim. Winter wheat cell lines were selected on medium with the addition of lethal doses of Cd2+ cations. Those variants demonstrated stable growth under osmotic stress pressure. The aim of the investigation was the estimation of cell protein status during cultivation under various conditions. Methods. Cd-resistant cell lines of winter wheat (cv. Favoritka) were cultivated under normal conditions and on cultural media with addition of lethal doses of manitol or Cd2+ (stresses I, II). From calli tissues crude protein matter was obtained and detected by Laemmli system electrophoresis. Results. Cd-resistant winter cell lines showed stable growth under any abiotic stress pressure. Electrophoregrams demonstrated peculiar features of some protein fraction accumulation that correlated with the age of cultures and type of stress agent. Conclusions. There were no decrease of total protein pools in calli tissues during cell cultivation under any (manitol, Cd2+) lethal stress pressure. The quantitative accumulation of some protein fractions were correlated with the type of stress agent. This event was especially manifested in variants, cultivated on media with manitol addition. Protein status of Cd-resistant cell lines of winter wheat is the reflection of their combined stress tolerance. Keywords: winter wheat, cell selection, cadmium ions, osmotic stress, tolerant cell line, protein.