Ribosome and protein synthesis are major metabolic events that control cellular growth and proliferation. Impairment in ribosome biogenesis pathways and mRNA translation is associated with pathologies such as cancer and developmental disorders. Processes that control global protein synthesis are tightly regulated at different levels by numerous factors and linked with multiple cellular signaling pathways. Several of these merge on the growth promoting factor c-Myc, which induces ribosome biogenesis by stimulating Pol I, Pol II, and Pol III transcription. However, how cells sense and respond to mRNA translation stress is not well understood. It was more recently shown that mRNA translation stress activates c-Myc, through a specific induction of E2F1 synthesis via a PI3Kδ-dependent pathway. This review focuses on how this novel feedback pathway stimulates cellular growth and proliferation pathways to synchronize protein synthesis with ribosome biogenesis. It also describes for the first time the oncogenic activity of the mRNA, and not the encoded protein.

• MeSH
• buněčný cyklus MeSH
• fyziologický stres * MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• náchylnost k nemoci MeSH
• nádory etiologie   metabolismus   MeSH
• proliferace buněk MeSH
• proteosyntéza * MeSH
• ribozomy metabolismus   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

The c-myc oncogene stimulates ribosomal biogenesis and protein synthesis to promote cellular growth. However, the pathway by which cells sense and restore dysfunctional mRNA translation and how this is linked to cell proliferation and growth is not known. We here show that mRNA translation stress in cis triggered by the gly-ala repeat sequence of Epstein-Barr virus (EBV)-encoded EBNA1, results in PI3Kδ-dependent induction of E2F1 mRNA translation with the consequent activation of c-Myc and cell proliferation. Treatment with a specific PI3Kδ inhibitor Idelalisib (CAL-101) suppresses E2F1 and c-Myc levels and causes cell death in EBNA1-induced B cell lymphomas. Suppression of PI3Kδ prevents E2F1 activation also in non-EBV-infected cells. These data illustrate an mRNA translation stress-response pathway for E2F1 activation that is exploited by EBV to promote cell growth and proliferation, offering new strategies to treat EBV-carrying cancers.

• MeSH
• buněčné linie MeSH
• fosfatidylinositol-3-kinasy třídy I genetika   metabolismus   MeSH
• interakce hostitele a patogenu genetika   MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory genetika   patologie   virologie   MeSH
• proliferace buněk genetika   MeSH
• proteosyntéza * MeSH
• regulace genové exprese u nádorů MeSH
• transkripční faktor E2F1 genetika   metabolismus   MeSH
• virus Epsteinův-Barrové - jaderné antigeny genetika   metabolismus   MeSH
• virus Epsteinův-Barrové genetika   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

7-(2-Thienyl)-7-deazaadenosine (AB61) showed nanomolar cytotoxic activities against various cancer cell lines but only mild (micromolar) activities against normal fibroblasts. The selectivity of AB61 was found to be due to inefficient phosphorylation of AB61 in normal fibroblasts. The phosphorylation of AB61 in the leukemic CCRF-CEM cell line proceeds well and it was shown that AB61 is incorporated into both DNA and RNA, preferentially as a ribonucleotide. It was further confirmed that a triphosphate of AB61 is a substrate for both RNA and DNA polymerases in enzymatic assays. Gene expression analysis suggests that AB61 affects DNA damage pathways and protein translation/folding machinery. Indeed, formation of large 53BP1 foci was observed in nuclei of AB61-treated U2OS-GFP-53BP1 cells indicating DNA damage. Random incorporation of AB61 into RNA blocked its translation in an in vitro assay and reduction of reporter protein expression was also observed in mice after 4-hour treatment with AB61. AB61 also significantly reduced tumor volume in mice bearing SK-OV-3, BT-549, and HT-29 xenografts. The results indicate that AB61 is a promising compound with unique mechanism of action and deserves further development as an anticancer agent. Mol Cancer Ther; 15(5); 922-37. ©2016 AACR.

• MeSH
• analýza přežití MeSH
• antitumorózní látky chemie   metabolismus   farmakologie   MeSH
• DNA genetika   metabolismus   MeSH
• fibroblasty MeSH
• lidé MeSH
• messenger RNA genetika   metabolismus   MeSH
• modely nemocí na zvířatech MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádory farmakoterapie   genetika   metabolismus   patologie   MeSH
• permeabilita buněčné membrány účinky léků   MeSH
• poškození DNA účinky léků   MeSH
• proliferace buněk účinky léků   MeSH
• proteosyntéza účinky léků   MeSH
• regulace genové exprese u nádorů MeSH
• sbalování proteinů účinky léků   MeSH
• tubercidin analogy a deriváty   chemie   metabolismus   farmakologie   MeSH
• výsledek terapie MeSH
• xenogenní modely - testy antitumorózní aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Cell growth requires a high level of protein synthesis and oncogenic pathways stimulate cell proliferation and ribosome biogenesis. Less is known about how cells respond to dysfunctional mRNA translation and how this feeds back into growth regulatory pathways. The Epstein-Barr virus (EBV)-encoded EBNA1 causes mRNA translation stress in cis that activates PI3Kδ. This leads to the stabilization of MDM2, induces MDM2's binding to the E2F1 mRNA and promotes E2F1 translation. The MDM2 serine 166 regulates the interaction with the E2F1 mRNA and deletion of MDM2 C-terminal RING domain results in a constitutive E2F1 mRNA binding. Phosphorylation on serine 395 following DNA damage instead regulates p53 mRNA binding to its RING domain and prevents the E2F1 mRNA interaction. The p14Arf tumour suppressor binds MDM2 and in addition to preventing degradation of the p53 protein it also prevents the E2F1 mRNA interaction. The data illustrate how two MDM2 domains selectively bind specific mRNAs in response to cellular conditions to promote, or suppress, cell growth and how p14Arf coordinates MDM2's activity towards p53 and E2F1. The data also show how EBV via EBNA1-induced mRNA translation stress targets the E2F1 and the MDM2 - p53 pathway.

• MeSH
• buněčný cyklus genetika   MeSH
• fosforylace genetika   MeSH
• karcinogeneze genetika   MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• nádorový supresorový protein p14ARF genetika   MeSH
• nádorový supresorový protein p53 genetika   MeSH
• nádory genetika   virologie   MeSH
• onkogeny genetika   MeSH
• poškození DNA genetika   MeSH
• proliferace buněk genetika   MeSH
• proteinové domény genetika   MeSH
• protoonkogenní proteiny c-mdm2 genetika   MeSH
• RRM proteiny genetika   MeSH
• transkripční faktor E2F1 genetika   MeSH
• tumor supresorové geny MeSH
• virus Epsteinův-Barrové genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH