Background: Though tyrosine kinase inhibitors managed to reach outstanding responses in the treatment of Chronic Myeloid Leukemia, resistance is still a challenging point, occurring in approximately 10–20% of the cases, due to several mechanisms. STAT5 expression has been strictly linked to resistance and disease progression and may thus represent a significant target to overcome resistance to TKI in CML. The aim of the study is to explore the in vitro antineoplastic role of the STAT5 inhibitor Pimozide in association with 2nd and 3rd generation inhibitors on chronic myeloid leukemia cells. Methods: The cytotoxic effect was evaluated by the Trypan blue dye exclusion test. K562 cell lines were exposed to pimozide alone and in association with ponatinib and dasatinib at different concentrations to explore the drugs association effect and the in vitro cytotoxic concentrations. Conclusions: Pimozide showed a synergic effect when associated with ponatinib and dasatinib in survival inhibition of K562 cell lines. This results are of note and pave the way for a possible in vivo associations.

A pattern of NK cell heterogeneity in each individual determines proliferative and functional responses of NK cells to activating stimuli. Obtaining the progeny of a single cell by cloning original population is one of the ways to study the NK cell heterogeneity. In this work, we used single cell sorting into a plate and stimulation by IL-2 and gene-modified K562 feeder cells expressing membrane-bound IL-21 (K562-mbIL21) that led to generation of phenotypically confirmed and functionally active NK cell clones. We applied two models of clone cultivation, which differently affected their phenotype, lifespan and functional activity. The first model, which included weekly restimulation of clones with K562-mbIL21 and IL-2, resulted in the generation of relatively short-lived (5-7 weeks) clones of highly activated NK cells. HLA-DR expression in the expanded NK cells correlated strongly with IFN-γ production. The second model, in which NK cells were restimulated mainly with IL-2 alone, produced long-lived clones (8-14 weeks) that expanded up to 10⁷ cells with lower ability to produce IFN-γ. Our method is applicable for studying variability in phenotype, proliferative and functional activity of the certain NK cell progeny in response to the stimulation, which may help in selecting NK cells best suited for clinical use.

Pretreatment of cells with proteolysis inhibitors diminished intensity and changed shape of DNICs specific EPR signal in a treatment time-dependent manner. The level of DNIC formation was significantly influenced by the presence of protein degradation products. Interestingly, formation of HMWDNICs depended on the availability of LMWDNICs. The extent of glutathione involvement in the in vivo formation of DNICs is minor yet noticeable, aligning with our prior research findings.