The c-Myb transcription factor is important for maintenance of immature cells of many tissues including colon epithelium. Overexpression of c-Myb occurring in colorectal carcinomas (CRC) as well as in other cancers often marks poor prognosis. However, the molecular mechanism explaining how c-Myb contributes to progression of CRC has not been fully elucidated. To address this point, we investigated the way how c-Myb affects sensitivity of CRC cells to anticancer drugs. Using CRC cell lines expressing exogenous c-myb we show that c-Myb protects CRC cells from the cisplatin-, oxaliplatin-, and doxorubicin-induced apoptosis, elevates reactive oxygen species via up-regulation of NOX1, and sustains the pro-survival p38 MAPK pathway. Using pharmacological inhibitors and gene silencing of p38 and NOX1 we found that these proteins are essential for the protective effect of c-Myb and that NOX1 acts upstream of p38 activation. In addition, our result suggests that transcription of NOX1 is directly controlled by c-Myb and these genes are strongly co-expressed in human tumor tissue of CRC patients. The novel c-Myb/NOX1/p38 signaling axis that protects CRC cells from chemotherapy described in this study could provide a new base for design of future therapies of CRC.

• Klíčová slova
• Cell survival, Colorectal carcinoma, NADPH oxidase, Reactive oxygen species, Signaling pathway, c-Myb,
• MeSH
• aktivace enzymů účinky léků   MeSH
• apoptóza účinky léků   MeSH
• cisplatina farmakologie   MeSH
• doxorubicin farmakologie   MeSH
• kolorektální nádory genetika   patologie   MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• mitogenem aktivované proteinkinasy p38 genetika   metabolismus   MeSH
• myši MeSH
• NADH, NADPH oxidoreduktasy genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• NADPH-oxidasa 1 MeSH
• NADPH-oxidasy genetika   metabolismus   MeSH
• organoplatinové sloučeniny farmakologie   MeSH
• oxaliplatin MeSH
• oxidační stres účinky léků   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• protoonkogenní proteiny c-myb metabolismus   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• regulace genové exprese u nádorů * účinky léků   MeSH
• sekvence nukleotidů MeSH
• upregulace účinky léků   MeSH
• vazebná místa MeSH
• viabilita buněk MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cisplatina MeSH
• doxorubicin MeSH
• messenger RNA MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• NADH, NADPH oxidoreduktasy MeSH
• NADPH-oxidasa 1 MeSH
• NADPH-oxidasy MeSH
• NOX1 protein, human MeSH Prohlížeč
• NOX1 protein, mouse MeSH Prohlížeč
• organoplatinové sloučeniny MeSH
• oxaliplatin MeSH
• protoonkogenní proteiny c-myb MeSH
• reaktivní formy kyslíku 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-oxidasa 1 MeSH
• NADPH-oxidasa 4 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
• Názvy látek
• interferon gama MeSH
• NADPH-oxidasa 1 MeSH
• NADPH-oxidasa 4 MeSH
• NADPH-oxidasy MeSH
• NOX1 protein, human MeSH Prohlížeč
• NOX4 protein, human MeSH Prohlížeč
• proteiny Smad MeSH
• reaktivní formy kyslíku MeSH
• TNF-alfa MeSH
• transformující růstový faktor beta MeSH
• transkripční faktory STAT MeSH
• translokátor adeninových nukleotidů 2 MeSH