Accumulation of senescent cells in tissues with advancing age participates in the pathogenesis of several human age-associated diseases. Specific senescent secretome, the resistance of senescent cells to apoptotic stimuli, and lack of immune system response contribute to the accumulation of senescent cells and their adverse effects in tissues. Inhibition of antiapoptotic machinery, augmented in senescent cells, by BCL-2 protein family inhibitors represents a promising approach to eliminate senescent cells from tissues. This study aimed to explore synergistic and selective senolytic effects of anti-apoptotic BCL-2 family targeting compounds, particularly BH3 mimetics. Using human non-transformed cells RPE-1, BJ, and MRC-5 brought to ionizing radiation-, oncogene-, drug-induced and replicative senescence, we found synergy in combining MCL-1 selective inhibitors with other BH3 mimetics. In an attempt to uncover the mechanism of such synergy, we revealed that the surviving subpopulation of cells resistant to individually applied ABT-737/ABT-263, MIK665, ABT-199, and S63845 BCL-2 family inhibitors showed elevated MCL-1 compared to untreated control cells indicating the presence of a subset of cells expressing high MCL-1 levels and, therefore, resistant to BCL-2 inhibitors within the original population of senescent cells. Overall, we found that combining BCL-2 inhibitors can be beneficial for eliminating senescent cells, thereby enabling use of lower, potentially less toxic, doses of drugs compared to monotherapy, thereby overcoming the resistance of the subpopulation of senescent cells to monotherapy.

• Klíčová slova
• BCL-2, MCL-1, cellular senescence, homoharringtonine, senolytics,
• MeSH
• apoptóza MeSH
• lidé MeSH
• protein MCL-1 metabolismus   MeSH
• protoonkogenní proteiny c-bcl-2 * antagonisté a inhibitory   MeSH
• stárnutí buněk * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• protein MCL-1 MeSH
• protoonkogenní proteiny c-bcl-2 * MeSH

Cellular senescence is a complex stress response defined as an essentially irreversible cell cycle arrest mediated by the inhibition of cell cycle-specific cyclin dependent kinases. The imbalance in redox homeostasis and oxidative stress have been repeatedly observed as one of the hallmarks of the senescent phenotype. However, a large-scale study investigating protein oxidation and redox signaling in senescent cells in vitro has been lacking. Here we applied a proteome-wide analysis using SILAC-iodoTMT workflow to quantitatively estimate the level of protein sulfhydryl oxidation and proteome level changes in ionizing radiation-induced senescence (IRIS) in hTERT-RPE-1 cells. We observed that senescent cells mobilized the antioxidant system to buffer the increased oxidation stress. Among the antioxidant proteins with increased relative abundance in IRIS, a unique 1-Cys peroxiredoxin family member, peroxiredoxin 6 (PRDX6), was identified as an important contributor to protection against oxidative stress. PRDX6 silencing increased ROS production in senescent cells, decreased their resistance to oxidative stress-induced cell death, and impaired their viability. Subsequent SILAC-iodoTMT and secretome analysis after PRDX6 silencing showed the downregulation of PRDX6 in IRIS affected protein secretory pathways, decreased expression of extracellular matrix proteins, and led to unexpected attenuation of senescence-associated secretory phenotype (SASP). The latter was exemplified by decreased secretion of pro-inflammatory cytokine IL-6 which was also confirmed after treatment with an inhibitor of PRDX6 iPLA2 activity, MJ33. In conclusion, by combining different methodological approaches we discovered a novel role of PRDX6 in senescent cell viability and SASP development. Our results suggest PRDX6 could have a potential as a drug target for senolytic or senomodulatory therapy.

• Klíčová slova
• Cellular senescence, Interleukin 6, Peroxiredoxin 6, Redox proteomics, SILAC-iodoTMT, Senescence-associated secretory phenotype,
• MeSH
• cytokiny * metabolismus   MeSH
• oxidace-redukce MeSH
• oxidační stres MeSH
• peroxiredoxin VI * genetika   metabolismus   MeSH
• stárnutí buněk fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cytokiny * MeSH
• peroxiredoxin VI * MeSH

Aging involves tissue accumulation of senescent cells (SC) whose elimination through senolytic approaches may evoke organismal rejuvenation. SC also contribute to aging-associated pathologies including cancer, hence it is imperative to better identify and target SC. Here, we aimed to identify new cell-surface proteins differentially expressed on human SC. Besides previously reported proteins enriched on SC, we identified 78 proteins enriched and 73 proteins underrepresented in replicatively senescent BJ fibroblasts, including L1CAM, whose expression is normally restricted to the neural system and kidneys. L1CAM was: 1) induced in premature forms of cellular senescence triggered chemically and by gamma-radiation, but not in Ras-induced senescence; 2) induced upon inhibition of cyclin-dependent kinases by p16INK4a; 3) induced by TGFbeta and suppressed by RAS/MAPK(Erk) signaling (the latter explaining the lack of L1CAM induction in RAS-induced senescence); and 4) induced upon downregulation of growth-associated gene ANT2, growth in low-glucose medium or inhibition of the mevalonate pathway. These data indicate that L1CAM is controlled by a number of cell growth- and metabolism-related pathways during SC development. Functionally, SC with enhanced surface L1CAM showed increased adhesion to extracellular matrix and migrated faster. Our results provide mechanistic insights into senescence of human cells, with implications for future senolytic strategies.

• Klíčová slova
• MAPK pathway, SILAC, aging, mass spectrometry, proteomics,
• MeSH
• buněčná adheze fyziologie   MeSH
• buněčný cyklus MeSH
• down regulace MeSH
• fibroblasty MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• lidé MeSH
• molekula buněčné adheze nervové L1 genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• pohyb buněk fyziologie   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• regulace genové exprese účinky léků   účinky záření   MeSH
• RNA interference MeSH
• signální transdukce MeSH
• stárnutí buněk MeSH
• transformující růstový faktor beta metabolismus   farmakologie   MeSH
• záření gama MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• molekula buněčné adheze nervové L1 MeSH
• transformující růstový faktor beta MeSH