As the genomic region containing the Bcl-2-related ovarian killer (BOK) locus is frequently deleted in certain human cancers, BOK is hypothesized to have a tumor suppressor function. In the present study, we analyzed primary non-small-cell lung carcinoma (NSCLC) tumors and matched lung tissues from 102 surgically treated patients. We show that BOK protein levels are significantly downregulated in NSCLC tumors as compared to lung tissues (p < 0.001). In particular, we found BOK downregulation in NSCLC tumors of grades two (p = 0.004, n = 35) and three (p = 0.031, n = 39) as well as in tumors with metastases to hilar (pN1) (p = 0.047, n = 31) and mediastinal/subcarinal lymph nodes (pN2) (p = 0.021, n = 18) as opposed to grade one tumors (p = 0.688, n = 7) and tumors without lymph node metastases (p = 0.112, n = 51). Importantly, in lymph node-positive patients, BOK expression greater than the median value was associated with longer survival (p = 0.002, Mantel test). Using in vitro approaches, we provide evidence that BOK overexpression is inefficient in inducing apoptosis but that it inhibits TGFβ-induced migration and epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma-derived A549 cells. We have identified epigenetic mechanisms, in particular BOK promoter methylation, as an important means to silence BOK expression in NSCLC cells. Taken together, our data point toward a novel mechanism by which BOK acts as a tumor suppressor in NSCLC by inhibiting EMT. Consequently, the restoration of BOK levels in low-BOK-expressing tumors might favor the overall survival of NSCLC patients.

• Klíčová slova
• BOK, Bcl-2 family, apoptosis, epithelial-to-mesenchymal transition, non-small-cell lung carcinoma,
• MeSH
• adenokarcinom genetika   metabolismus   sekundární   MeSH
• apoptóza * MeSH
• epitelo-mezenchymální tranzice MeSH
• lidé MeSH
• lymfatické metastázy MeSH
• míra přežití MeSH
• nádorové biomarkery genetika   metabolismus   MeSH
• nádorové buňky kultivované MeSH
• nádory plic genetika   metabolismus   patologie   MeSH
• nemalobuněčný karcinom plic genetika   metabolismus   sekundární   MeSH
• prognóza MeSH
• protoonkogenní proteiny c-bcl-2 genetika   metabolismus   MeSH
• spinocelulární karcinom genetika   metabolismus   sekundární   MeSH
• staging nádorů MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• BOK protein, human MeSH Prohlížeč
• nádorové biomarkery MeSH
• protoonkogenní proteiny c-bcl-2 MeSH

The intrinsic apoptosis pathway represents an important mechanism of stress-induced death of cancer cells. To gain insight into the functional status of the apoptosome apparatus in non-small cell lung carcinoma (NSCLC), we studied its sensitivity to activation, the assembly of apoptosome complexes and stability of their precursors, and the importance of X-linked inhibitor of apoptosis (XIAP) in the regulation of apoptosome activity, using cell-free cytosols from NSCLC cell lines and NSCLC tumours and lungs from 62 surgically treated patients. Treatment of cytosol samples with cytochrome c (cyt-c) and dATP induced proteolytic processing of procaspase-9 to caspase-9, which was followed by procaspase-3 processing to caspase-3, and by generation of caspase-3-like activity in 5 of 7 studied NSCLC cell lines. Further analysis demonstrated formation of high-Mr Apaf-1 complexes associated with cleaved caspase-9 in the (cyt-c + dATP)-responsive COLO-699 and CALU-1 cells. By contrast, in A549 cells, Apaf-1 and procaspase-9 co-eluted in the high-Mr fractions, indicating formation of an apoptosome complex unable of procaspase-9 processing. Thermal pre-treatment of cell-free cytosols in the absence of exogenous cyt-c and dATP lead to formation of Apaf-1 aggregates, unable to recruit and activate procaspase-9 in the presence of cyt-c and dATP, and to generate caspase‑3‑like activity. Further studies showed that the treatment with cyt-c and dATP induced a substantially higher increase of caspase-3-like activity in cytosol samples from NSCLC tumours compared to matched lungs. Tumour histology, grade and stage had no significant impact on the endogenous and the (cyt-c + dATP)-induced caspase-3-like activity. Upon addition into the cytosol, the XIAP-neutralizing peptides AVPIAQK and ATPFQEG only moderately heightened the (cyt-c + dATP)-induced caspase‑3‑like activity in some NSCLC tumours. Taken together, the present study provides evidence that the apoptosome apparatus is functional in the majority of NSCLCs and that its sensitivity to the (cyt-c + dATP)-mediated activation is often enhanced in NSCLCs compared to lungs. They also indicate that XIAP does not frequently and effectively suppress the activity of apoptosome apparatus in NSCLCs.

• MeSH
• apoptóza * účinky léků   MeSH
• cytochromy c farmakologie   MeSH
• cytosol metabolismus   MeSH
• deoxyadeninnukleotidy farmakologie   MeSH
• faktor 1 aktivující apoptotickou proteasu metabolismus   MeSH
• inhibitory kaspas farmakologie   MeSH
• kaspasa 3 metabolismus   MeSH
• kaspasa 9 metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádory plic metabolismus   patologie   MeSH
• nemalobuněčný karcinom plic metabolismus   patologie   MeSH
• plíce cytologie   metabolismus   MeSH
• regulace genové exprese u nádorů MeSH
• senioři MeSH
• X-vázaný inhibitor apoptózy farmakologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 2'-deoxyadenosine triphosphate MeSH Prohlížeč
• cytochromy c MeSH
• deoxyadeninnukleotidy MeSH
• faktor 1 aktivující apoptotickou proteasu MeSH
• inhibitory kaspas MeSH
• kaspasa 3 MeSH
• kaspasa 9 MeSH
• X-vázaný inhibitor apoptózy MeSH