ΔNp63, also known as p40, regulates stemness of normal mammary gland epithelium and provides stem cell characteristics in basal and HER2-driven murine breast cancer models. Whilst ΔNp63/p40 is a characteristic feature of normal basal cells and basal-type triple-negative breast cancer, some receptor-positive breast cancers express ΔNp63/p40 and its overexpression imparts cancer stem cell-like properties in ER+ cell lines. However, the incidence of ER+ and HER2+ tumours that express ΔNp63/p40 is unclear and the phenotype of ΔNp63/p40+ cells in these tumours remains uncertain. Using immunohistochemistry with p63 isoform-specific antibodies, we identified a ΔNp63/p40+ tumour cell subpopulation in 100 of 173 (58%) non-triple negative breast cancers and the presence of this population associated with improved survival in patients with ER- /HER2+ tumours (p = 0.006). Furthermore, 41% of ER+ /PR+ and/or HER2+ locally metastatic breast cancers expressed ΔNp63/p40, and these cells commonly accounted for <1% of the metastatic tumour cell population that localised to the tumour/stroma interface, exhibited an undifferentiated phenotype and were CD44+ /ALDH- . In vitro studies revealed that MCF7 and T47D (ER+ ) and BT-474 (HER2+ ) breast cancer cell lines similarly contained a small subpopulation of ΔNp63/p40+ cells that increased in mammospheres. In vivo, MCF7 xenografts contained ΔNp63/p40+ cells with a similar phenotype to primary ER+ cancers. Consistent with tumour samples, these cells also showed a distinct location at the tumour/stroma interface, suggesting a role for paracrine factors in the induction or maintenance of ΔNp63/p40. Thus, ΔNp63/p40 is commonly present in a small population of tumour cells with a distinct phenotype and location in ER+ and/or HER2+ human breast cancers.

• Klíčová slova
• CD44, HER2, aldehyde dehydrogenase, breast, cancer stem cells, oestrogen receptor, p40, p63, ΔNp63,
• MeSH
• fenotyp MeSH
• heterografty MeSH
• lidé MeSH
• myši MeSH
• nádorové biomarkery analýza   metabolismus   MeSH
• nádorové kmenové buňky metabolismus   patologie   MeSH
• nádorové supresorové proteiny metabolismus   MeSH
• nádory prsu genetika   metabolismus   patologie   MeSH
• receptor erbB-2 genetika   metabolismus   MeSH
• receptory pro estrogeny genetika   metabolismus   MeSH
• transkripční faktory metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ERBB2 protein, human MeSH Prohlížeč
• nádorové biomarkery MeSH
• nádorové supresorové proteiny MeSH
• receptor erbB-2 MeSH
• receptory pro estrogeny MeSH
• TP63 protein, human MeSH Prohlížeč
• transkripční faktory MeSH

Drugs targeting MDM2's hydrophobic pocket activate p53. However, these agents act allosterically and have agonist effects on MDM2's protein interaction landscape. Dominant p53-independent MDM2-drug responsive-binding proteins have not been stratified. We used as a variable the differential expression of MDM2 protein as a function of cell density to identify Nutlin-3 responsive MDM2-binding proteins that are perturbed independent of cell density using SWATH-MS. Dihydrolipoamide dehydrogenase, the E3 subunit of the mitochondrial pyruvate dehydrogenase complex, was one of two Nutlin-3 perturbed proteins identified fours hour posttreatment at two cell densities. Immunoblotting confirmed that dihydrolipoamide dehydrogenase was induced by Nutlin-3. Depletion of MDM2 using siRNA also elevated dihydrolipoamide dehydrogenase in Nutlin-3 treated cells. Mitotracker confirmed that Nutlin-3 inhibits mitochondrial activity. Enrichment of mitochondria using TOM22+ immunobeads and TMT labeling defined key changes in the mitochondrial proteome after Nutlin-3 treatment. Proximity ligation identified rearrangements of cellular protein-protein complexes in situ. In response to Nutlin-3, a reduction of dihydrolipoamide dehydrogenase/dihydrolipoamide acetyltransferase protein complexes highlighted a disruption of the pyruvate dehydrogenase complex. This coincides with an increase in MDM2/dihydrolipoamide dehydrogenase complexes in the nucleus that was further enhanced by the nuclear export inhibitor Leptomycin B. The data suggest one therapeutic impact of MDM2 drugs might be on the early perturbation of specific protein-protein interactions within the mitochondria. This methodology forms a blueprint for biomarker discovery that can identify rearrangements of MDM2 protein-protein complexes in drug-treated cells.

• Klíčová slova
• Cell biology, MDM2, Mitochondria, Nutlin-3, P53, SWATH-MS,
• MeSH
• dihydrolipoamiddehydrogenasa metabolismus   MeSH
• HCT116 buňky MeSH
• imidazoly farmakologie   MeSH
• lidé MeSH
• mapy interakcí proteinů účinky léků   MeSH
• membránový potenciál mitochondrií účinky léků   MeSH
• mitochondrie účinky léků   metabolismus   MeSH
• piperaziny farmakologie   MeSH
• protoonkogenní proteiny c-mdm2 metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• dihydrolipoamiddehydrogenasa MeSH
• imidazoly MeSH
• nutlin 3 MeSH Prohlížeč
• piperaziny MeSH
• protoonkogenní proteiny c-mdm2 MeSH

The tumor suppressor p53 plays a key role in malignant transformation and tumor development. However, the frequency of p53 mutations within individual types of cancer is different, suggesting the existence of other mechanisms attenuating p53 tumor suppressor activity. Changes in upstream regulators of p53 such as MDM2 amplification and overexpression, expression of viral oncoproteins, estrogen receptor signaling, or changes in p53 transcriptional target genes were previously described in wild-type p53 tumors. We identified a novel pathway responsible for attenuation of p53 activity in human cancers. We demonstrate that AGR2, which is overexpressed in a variety of human cancers and provides a poor prognosis, up-regulates DUSP10 which subsequently inhibits p38 MAPK and prevents p53 activation by phosphorylation. Analysis of human breast cancers reveals that AGR2 specifically provides a poor prognosis in ER+ breast cancers with wild-type p53 but not ER- or mutant p53 breast cancers, and analysis of independent data sets show that DUSP10 levels also have prognostic significance in this specific sub-group of patients. These data not only reveal a novel pro-oncogenic signaling pathway mediating resistance to DNA damaging agents in human tumors, but also has implications for designing alternative strategies for modulation of wild-type p53 activity in cancer therapy.

• Klíčová slova
• AGR2, Breast cancer, DUSP10, Drug resistance, p38 MAPK, p53,
• MeSH
• aktivace enzymů účinky léků   MeSH
• chemorezistence MeSH
• dospělí MeSH
• fosfatasy MAP kinas metabolismus   MeSH
• fosfatasy s dvojí specifitou metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• mukoproteiny MeSH
• nádorové buněčné linie MeSH
• nádorový supresorový protein p53 metabolismus   MeSH
• nádory prsu farmakoterapie   metabolismus   patologie   MeSH
• nádory farmakoterapie   metabolismus   patologie   MeSH
• onkogenní proteiny MeSH
• proteiny metabolismus   MeSH
• protinádorové látky farmakologie   MeSH
• prsy účinky léků   metabolismus   patologie   MeSH
• senioři MeSH
• signální transdukce * účinky léků   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• AGR2 protein, human MeSH Prohlížeč
• DUSP10 protein, human MeSH Prohlížeč
• fosfatasy MAP kinas MeSH
• fosfatasy s dvojí specifitou MeSH
• mitogenem aktivované proteinkinasy p38 MeSH
• mukoproteiny MeSH
• nádorový supresorový protein p53 MeSH
• onkogenní proteiny MeSH
• proteiny MeSH
• protinádorové látky MeSH