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Natural killer (NK) cells are central components of the innate immunity system against cancers. Since tumor cells have evolved a series of mechanisms to escape from NK cells, developing methods for increasing the NK cell antitumor activity is of utmost importance. It is previously shown that an ex vivo stimulation of patient‐derived NK cells with interleukin (IL)‐2 and Hsp70‐derived peptide TKD (TKDNNLLGRFELSG, aa450‐461) results in a significant upregulation of activating receptors including CD94 and CD69 which triggers exhausted NK cells to target and kill malignant solid tumors expressing membrane Hsp70 (mHsp70). Considering that TKD binding to an activating receptor is the initial step in the cytolytic signaling cascade of NK cells, herein this interaction is studied by molecular docking and molecular dynamics simulation computational modeling. The in silico results showed a crucial role of the heterodimeric receptor CD94/NKG2A and CD94/NKG2C in the TKD interaction with NK cells. Antibody blocking and CRISPR/Cas9–mediated knockout studies verified the key function of CD94 in the TKD stimulation and activation of NK cells which is characterized by an increased cytotoxic capacity against mHsp70 positive tumor cells via enhanced production and release of lytic granules and pro‐inflammatory cytokines. [ABSTRACT FROM AUTHOR]

The senescence is proposed as a defense mechanism against many anticancer drugs. This complication is marked by differences in cell appearance and inner structures underlying the impairment in function. In this experiment, doxorubicin‐induced senescence was assessed in mesenchymal stem cells (MSCs) isolated from the bone marrow of different‐aged Balb/c mice (1, 8, and 16 months old). In addition, doxorubicin kinetics in culture medium were investigated to compare the drug absorption rate by different‐aged MSCs. Several methods were exerted including Sandwich ELISA for NF‐κB activation, propidium iodide staining for cell cycle analysis, Flow‐fluorescent in‐situ hybridization (Flow‐FISH) assay for telomere length measurement, and specific staining for evaluation of β‐galactosidase. Determination of doxorubicin in a medium was performed by high‐performance liquid chromatography technique. Following doxorubicin exposure, cells underwent substantial telomere shortening, cell cycle arresting in G2 phase, and increased β‐galactosidase activity. Interestingly, the enhanced level of NF‐κB was observed in all age groups. The highest and lowest sensitivity to telomere shortening attributed to 1‐ and 8‐month‐old MSCs, respectively. In consistent with Flow‐FISH results, the β‐galactosidase activity was higher in young‐aged MSCs after treatment. Statistical analysis indicated a correlation between the reduction of telomere length and cessation in G2 phase. Regarding the obtained kinetics equations, the rate of doxorubicin absorption by all aged MSCs followed the same trend. In conclusion, the changing of some elements involved in doxorubicin‐induced senescence can be affected by the age of the cells significantly in young MSCs than two other age groups. Hereupon, these changing patterns can open new insights to develop anticancer therapeutic strategies. [ABSTRACT FROM AUTHOR]