While type I interferon (IFN) is best known for its key role against viral infection, accumulating preclinical and clinical data indicate that robust type I IFN production in the tumor microenvironment promotes cancer immunosurveillance and contributes to the efficacy of various antineoplastic agents, notably immunogenic cell death inducers. Here, we report that malignant blasts from patients with acute myeloid leukemia (AML) release type I IFN via a Toll-like receptor 3 (TLR3)-dependent mechanism that is not driven by treatment. While in these patients the ability of type I IFN to stimulate anticancer immune responses was abolished by immunosuppressive mechanisms elicited by malignant blasts, type I IFN turned out to exert direct cytostatic, cytotoxic and chemosensitizing activity in primary AML blasts, leukemic stem cells from AML patients and AML xenograft models. Finally, a genetic signature of type I IFN signaling was found to have independent prognostic value on relapse-free survival and overall survival in a cohort of 132 AML patients. These findings delineate a clinically relevant, therapeutically actionable and prognostically informative mechanism through which type I IFN mediates beneficial effects in patients with AML.
- MeSH
- akutní myeloidní leukemie * patologie MeSH
- interferon typ I * MeSH
- lidé MeSH
- nádorové mikroprostředí MeSH
- protinádorové látky * terapeutické užití MeSH
- signální transdukce MeSH
- výsledek terapie MeSH
- Check Tag
- lidé 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
- Publikační typ
- abstrakt z konference MeSH
Rhabdomyosarcomas (RMS) are a heterogeneous group of mesodermal tumors, the most common sub-types are embryonal (eRMS) and alveolar (aRMS) rhabdomyosarcoma. Immunohistochemical analysis revealed c-Myb expression in both eRMS and aRMS. c-Myb has been reported to be often associated with malignant human cancers. We therefore investigated the c-Myb role in RMS using cellular models of RMS. Specific suppression of c-Myb by a lentiviral vector expressing doxycycline (Dox)-inducible c-Myb shRNA inhibited proliferation, colony formation, and migration of the eRMS cell line (RD), but not of the aRMS cell line (RH30). Upon c-Myb knockdown in eRMS cells, cells accumulated in G0/G1 phase, the invasive behaviour of cells was repressed, and elevated levels of myosin heavy chain, marker of muscle differentiation, was detected. Next, we used an RD-based xenograft model to investigate the role of c-Myb in eRMS tumorigenesis in vivo. We found that Dox administration did not result in efficient suppression of c-Myb in growing tumors. However, when c-Myb-deficient RD cells were implanted into SCID mice, we observed inefficient tumor grafting and attenuation of tumor growth during the initial stages of tumor expansion. The presented study suggests that c-Myb could be a therapeutic target in embryonal rhabdomyosarcoma assuming that its expression is ablated.
- MeSH
- embryonální rhabdomyosarkom genetika metabolismus patologie MeSH
- G0 fáze * MeSH
- G1 fáze * MeSH
- genový knockdown MeSH
- karcinogeneze genetika metabolismus patologie MeSH
- myši MeSH
- nádorové buněčné linie MeSH
- protoonkogenní proteiny c-myb genetika metabolismus MeSH
- regulace genové exprese u nádorů * MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The transcription factor c-Myb is required for modulation of progenitor cells in several tissues, including skeletal muscle and its upregulation is observed in many human malignancies. Rhabdomyosarcomas (RMS) are a heterogeneous group of mesodermal tumors with features of developing skeletal muscle. Several miRNAs are downregulated in RMS, including miR-150, a negative regulator of c-Myb expression. Using the C2C12 myoblast cell line, a cellular model of skeletal muscle differentiation, we showed that miR-150 controls c-Myb expression mainly at the level of translation. We hypothesized that a similar mechanism of c-Myb regulation operates in RMS tumors. We examined expression of c-Myb by immunohistochemistry and revealed c-Myb positivity in alveolar and embryonal tumors, the two most common subgroups of RMS. Furthermore, we showed direct correlation between c-Myb production and myogenin expression. Interestingly, high myogenin levels indicate poor prognosis in RMS patients. c-Myb could, therefore, contribute to the tumor phenotype by executing its inhibitory role in skeletal muscle differentiation. We also showed that c-Myb protein is abundant in migratory C2C12 myoblasts and its ectopic expression potentiates cell motility. In summary, our results implicate that metastatic properties of some RMS subtypes might be linked to c-Myb function.
- MeSH
- lidé MeSH
- myogenin MeSH
- myši MeSH
- nádorové biomarkery metabolismus MeSH
- nádorové buněčné linie MeSH
- protoonkogenní proteiny c-myb metabolismus MeSH
- regulace genové exprese u nádorů * MeSH
- rhabdomyosarkom metabolismus patologie sekundární MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Satellite cells represent a heterogeneous population of stem and progenitor cells responsible for muscle growth, repair and regeneration. We investigated whether c-Myb could play a role in satellite cell biology because our previous results using satellite cell-derived mouse myoblast cell line C2C12 showed that c-Myb was expressed in growing cells and downregulated during differentiation. We detected c-Myb expression in activated satellite cells of regenerating muscle. c-Myb was also discovered in activated satellite cells associated with isolated viable myofiber and in descendants of activated satellite cells, proliferating myoblasts. However, no c-Myb expression was detected in multinucleated myotubes originated from fusing myoblasts. The constitutive expression of c-Myb lacking the 3' untranslated region (3' UTR) strongly inhibited the ability of myoblasts to fuse. The inhibition was dependent on intact c-Myb transactivation domain as myoblasts expressing mutated c-Myb in transactivation domain were able to fuse. The absence of 3' UTR of c-Myb was also important because the expression of c-Myb coding region with its 3' UTR did not inhibit myoblast fusion. The same results were repeated in C2C12 cells as well. Moreover, it was documented that 3' UTR of c-Myb was responsible for downregulation of c-Myb protein levels in differentiating C2C12 cells. DNA microarray analysis of C2C12 cells revealed that the expression of several muscle-specific genes was downregulated during differentiation of c-Myb-expressing cells, namely: ACTN2, MYH8, TNNC2, MYOG, CKM and LRRN1. A detailed qRT-PCR analysis of MYOG, TNNC2 and LRRN1 is presented. Our findings thus indicate that c-Myb is involved in regulating the differentiation program of myogenic progenitor cells as its expression blocks myoblast fusion.
- MeSH
- 3' nepřekládaná oblast genetika MeSH
- buněčná diferenciace genetika MeSH
- buněčné linie MeSH
- fúze buněk MeSH
- imunohistochemie MeSH
- kardiotoxiny farmakologie MeSH
- kosterní svalová vlákna cytologie metabolismus MeSH
- kosterní svaly účinky léků patofyziologie MeSH
- kultivované buňky MeSH
- myoblasty cytologie metabolismus MeSH
- myši inbrední BALB C MeSH
- myši MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- protoonkogenní proteiny c-myb genetika metabolismus MeSH
- regenerace účinky léků genetika MeSH
- satelitní buňky kosterního svalu cytologie metabolismus MeSH
- sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
- stanovení celkové genové exprese MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Analysis of c-myb gene down-regulation in differentiating C212 cells revealed that in proliferating cells, c-myb expression is high and ceases as the proliferation rate decreases. However, a low level of c-myb mRNA was detected in confluent non-proliferating differentiating cells for an extended period of time before it declined to an undetectable level. The time course of c-myb gene silencing in differentiating cells correlated with exposition of phosphatidylserine (PS) on the cell surface. Moreover, the interaction of exposed PS with exogenously added annexin V perturbed PS-mediated cell signaling and transiently up-regulated the declining c-myb expression. We, therefore, suggest that cell surface-exposed PS, which plays a role in the process of myotube formation, is also involved in the down-regulation of c-myb expression.
- MeSH
- annexin A5 metabolismus MeSH
- buněčná diferenciace MeSH
- buněčné linie MeSH
- DNA primery MeSH
- financování organizované MeSH
- fluorescenční protilátková technika MeSH
- fosfatidylseriny metabolismus MeSH
- messenger RNA genetika MeSH
- myši MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- protoonkogenní proteiny c-myb genetika MeSH
- sekvence nukleotidů MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
c-Myb, known to play a central role in hematopoiesis, is also an important factor involved in myogenesis. Here, we found that the c-myb gene is expressed in proliferating C2C12 myoblasts and turned off in differentiating cells. Detailed analysis of c-myb RNAs revealed that the cell density is the essential factor determining c-myb expression. Both c-myb and its alternatively spliced form c-mybE9A RNAs are down-regulated in confluent cells. Constitutive expression of exogenous c-myb in C2C12 cells inhibits their terminal differentiation. It is shown that the c-Myb protein physically interacts with MyoD, the key regulator of myogenesis, and inhibits MyoD-dependent transcription. The interaction domains are the DNA binding domain of c-Myb and the bHLH motif of MyoD. Our data suggest that in proliferating cells c-Myb binds MyoD and inhibits its transcriptional activity until cell-cell contacts are established and c-myb expression is switched off. Thus, the c-Myb protein may be one of factors ensuring that proliferating myoblasts remain undifferentiated.
- MeSH
- buněčná diferenciace fyziologie MeSH
- buněčné linie MeSH
- financování organizované MeSH
- myoblasty cytologie metabolismus MeSH
- MyoD Protein antagonisté a inhibitory metabolismus MeSH
- myogenní regulační faktory biosyntéza MeSH
- myši inbrední C3H MeSH
- myši MeSH
- počet buněk MeSH
- promotorové oblasti (genetika) MeSH
- protoonkogenní proteiny c-myb biosyntéza fyziologie genetika MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- MeSH
- antituberkulotika farmakologie terapeutické užití MeSH
- dítě MeSH
- lidé MeSH
- mnohočetná bakteriální léková rezistence MeSH
- Mycobacterium tuberculosis patogenita MeSH
- pleuritida diagnóza patologie terapie MeSH
- plicní tuberkulóza diagnóza patologie terapie MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- Publikační typ
- kazuistiky MeSH
- Geografické názvy
- Česká republika MeSH
