Cellular senescence is a form of cell cycle arrest that limits the proliferative potential of cells, including tumour cells. However, inability of immune cells to subsequently eliminate senescent cells from the organism may lead to tissue damage, inflammation, enhanced carcinogenesis and development of age-related diseases. We found that the anticancer agent mitochondria-targeted tamoxifen (MitoTam), unlike conventional anticancer agents, kills cancer cells without inducing senescence in vitro and in vivo. Surprisingly, it also selectively eliminates both malignant and non-cancerous senescent cells. In naturally aged mice treated with MitoTam for 4 weeks, we observed a significant decrease of senescence markers in all tested organs compared to non-treated animals. Mechanistically, we found that the susceptibility of senescent cells to MitoTam is linked to a very low expression level of adenine nucleotide translocase-2 (ANT2), inherent to the senescent phenotype. Restoration of ANT2 in senescent cells resulted in resistance to MitoTam, while its downregulation in non-senescent cells promoted their MitoTam-triggered elimination. Our study documents a novel, translationally intriguing role for an anticancer agent targeting mitochondria, that may result in a new strategy for the treatment of age-related diseases and senescence-associated pathologies.

• MeSH
• apoptóza účinky léků   genetika   MeSH
• genový knockdown MeSH
• hormonální protinádorové látky farmakologie   MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• myši inbrední NOD MeSH
• myši SCID MeSH
• myši transgenní MeSH
• myši MeSH
• proliferace buněk účinky léků   MeSH
• stárnutí buněk účinky léků   MeSH
• tamoxifen farmakologie   MeSH
• transfekce MeSH
• translokátor adeninových nukleotidů 2 genetika   metabolismus   MeSH
• viabilita buněk účinky léků   genetika   MeSH
• xenogenní modely - testy protinádorové aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Cellular senescence provides a biological barrier against tumor progression, often associated with oncogene-induced replication and/or oxidative stress, cytokine production and DNA damage response (DDR), leading to persistent cell-cycle arrest. While cytokines such as tumor necrosis factor-alpha (TNFα) and interferon gamma (IFNγ) are important components of senescence-associated secretome and induce senescence in, for example, mouse pancreatic β-cancer cell model, their downstream signaling pathway(s) and links with oxidative stress and DDR are mechanistically unclear. Using human and mouse normal and cancer cell models, we now show that TNFα and IFNγ induce NADPH oxidases Nox4 and Nox1, reactive oxygen species (ROS), DDR signaling and premature senescence. Unlike mouse tumor cells that required concomitant presence of IFNγ and TNFα, short exposure to IFNγ alone was sufficient to induce Nox4, Nox1 and DDR in human cells. siRNA-mediated knockdown of Nox4 but not Nox1 decreased IFNγ-induced DDR. The expression of Nox4/Nox1 required Janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling and the effect was mediated by downstream activation of transforming growth factor-beta (TGFβ) secretion and consequent autocrine/paracrine activation of the TGFβ/Smad pathway. Furthermore, the expression of adenine nucleotide translocase 2 (ANT2) was suppressed by IFNγ contributing to elevation of ROS and DNA damage. In contrast to mouse B16 cells, inability of TC-1 cells to respond to IFNγ/TNFα by DDR and senescence correlated with the lack of TGFβ and Nox4 response, supporting the role of ROS induced by NADPH oxidases in cytokine-induced senescence. Overall, our data reveal differences between cytokine effects in mouse and human cells, and mechanistically implicate the TGFβ/SMAD pathway, via induction of NADPH oxidases and suppression of ANT2, as key mediators of IFNγ/TNFα-evoked genotoxicity and cellular senescence.

• MeSH
• enzymová indukce účinky léků   MeSH
• interferon gama farmakologie   MeSH
• lidé MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• NADPH-oxidasy biosyntéza   genetika   MeSH
• oxidační stres účinky léků   MeSH
• poškození DNA * MeSH
• proteiny Smad metabolismus   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• regulace genové exprese u nádorů MeSH
• signální transdukce účinky léků   MeSH
• stárnutí buněk účinky léků   MeSH
• TNF-alfa farmakologie   MeSH
• transformující růstový faktor beta metabolismus   MeSH
• transkripční faktory STAT metabolismus   MeSH
• translokátor adeninových nukleotidů 2 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Oxidative stress and persistent activation of DNA damage response (DDR) are causally involved in the development of cellular senescence, a phenomenon implicated in fundamental (patho)physiological processes such as aging, fetal development and tumorigenesis. Here, we report that adenine nucleotide translocase-2 (ANT2) is consistently down-regulated in all three major forms of cellular senescence: replicative, oncogene-induced and drug-induced, in both normal and cancerous human cells. We previously reported formation of novel NF1/Smad transcription repressor complexes in growth-arrested fibroblasts. Here we show that such complexes form in senescent cells. Mechanistically, binding of the NF1/Smad complexes to the NF1-dependent repressor elements in the ANT2 gene promoter repressed ANT2 expression. Etoposide-induced formation of these complexes and repression of ANT2 were relatively late events co-incident with production and secretion of, and dependent on, TGF-β. siRNA-mediated knock-down of ANT2 in proliferating cells resulted in increased levels of reactive oxygen species (ROS) and activation of the DDR. Knock-down of ANT2, together with etoposide treatment, further intensified ROS production and DNA damage signaling, leading to enhanced apoptosis. Together, our data show that TGF-β-mediated suppression of ANT2 through NF1/Smad4 complexes contributes to oxidative stress and DNA damage during induction of cellular senescence.

• MeSH
• buněčné jádro účinky léků   metabolismus   MeSH
• buněčné linie MeSH
• cytoprotekce účinky léků   MeSH
• down regulace účinky léků   MeSH
• etoposid farmakologie   MeSH
• lidé MeSH
• mutace MeSH
• oxidační stres * účinky léků   MeSH
• poškození DNA MeSH
• promotorové oblasti (genetika) MeSH
• protein Smad4 metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• stárnutí buněk * účinky léků   MeSH
• transformující růstový faktor beta metabolismus   MeSH
• transkripční faktory NFI metabolismus   MeSH
• translokátor adeninových nukleotidů 2 genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH