Abstract:Expression of the adenoviral protein, E1A, sensitizes mammalian cells to a wide variety of apoptosis-inducing agents through multiple cellular pathways. For example, E1A sensitizes cells to apoptosis induced by TNF-superfamily members by inhibiting NF-kappa B (NF-κB)-dependent gene expression. In contrast, E1A sensitization to nitric oxide, an inducer of the intrinsic apoptotic pathway, is not dependent upon repression of NF-κB-dependent transcription but rather is dependent upon caspase-2 activation. The latt… Show more
“…Similar results were obtained with two different NIH-3T3-E1A-positive, PIDD knockdown cell lines (mouse NIH-3T3-E1AiPIDD) made previously in our laboratory (Fig. 2c ) 32 . Fig.…”
Section: Resultssupporting
confidence: 89%
“…NIH-3T3 cells expressing Ad5 E1A 12S protein (MT12-1) and its derivatives were maintained in DMEM supplemented with antibiotics and 5% calf serum 11 , 47 . 3T3-E1A+, Caspase-2-shRNA-expressing cells (E1A-iC2) and 3T3-E1A+PIDD-shRNA-expressing cells (E1A-iPIDD-1) have been characterized and were maintained in the presence of G418 and puromycin 11 , 32 . H4 cells (a subclone of the human fibrosarcoma cell line HT-1080) expressing genomic E1A (H4-E1A and P2AHT2A) and its derivatives were maintained in RPMI 1640 plus antibiotics and 10% fetal bovine serum (FBS) 48 .…”
Section: Methodsmentioning
confidence: 99%
“…E1A transformed BMK from wild type, Bak −/− , Bax −/− , and Bak −/− /Bax −/− mice were obtained from Eileen White and were maintained in DMEM with antibiotics and 10% FBS 34 . C-terminal FLAG-tagged PIDD S588A mutant (mtPIDD) was obtained from the laboratory of Jürg Tschopp, cloned into pcDNA3.1 (+)/Hygro (Invitrogen), transfected into E1A+ cells and selected with hygromycin 15 , 32 . Cell lines were negative for mycoplasma contamination.…”
Expression of the adenovirus E1A oncogene sensitizes tumor cells to innate immune rejection by apoptosis induced by macrophage-produced tumor necrosis factor (TNF)-α and nitric oxide (NO). E1A sensitizes cells to TNF-α and NO through two distinct mechanisms, by repressing NF-κB-dependent antiapoptotic responses and enhancing caspase-2 activation and mitochondrial injury, respectively. The mechanisms through which E1A enhances caspase-2 activation in response to NO were unknown. Here, we report that E1A-induced sensitization to NO-induced apoptosis is dependent on expression of PIDD (p53-inducible protein with a death domain) and enhancement of primary immunodeficiency diseases (PIDD) processing for formation of the PIDDosome, the core component of the caspase-2 activation complex. NO-induced apoptosis in E1A-expressing cells did not require expression Bak or Bax, indicating that NO-induced caspase-2-mediated mitochondrial injury does not proceed through the activities of typical, proapoptotic Bcl-2 family members that induce mitochondrial cytochrome C release. These results define a PIDD-dependent pathway, through which E1A enhances casapse-2-mediated mitochondrial injury, resulting in increased sensitivity of mammalian cells to macrophage-induced, NO-mediated apoptosis.
“…Similar results were obtained with two different NIH-3T3-E1A-positive, PIDD knockdown cell lines (mouse NIH-3T3-E1AiPIDD) made previously in our laboratory (Fig. 2c ) 32 . Fig.…”
Section: Resultssupporting
confidence: 89%
“…NIH-3T3 cells expressing Ad5 E1A 12S protein (MT12-1) and its derivatives were maintained in DMEM supplemented with antibiotics and 5% calf serum 11 , 47 . 3T3-E1A+, Caspase-2-shRNA-expressing cells (E1A-iC2) and 3T3-E1A+PIDD-shRNA-expressing cells (E1A-iPIDD-1) have been characterized and were maintained in the presence of G418 and puromycin 11 , 32 . H4 cells (a subclone of the human fibrosarcoma cell line HT-1080) expressing genomic E1A (H4-E1A and P2AHT2A) and its derivatives were maintained in RPMI 1640 plus antibiotics and 10% fetal bovine serum (FBS) 48 .…”
Section: Methodsmentioning
confidence: 99%
“…E1A transformed BMK from wild type, Bak −/− , Bax −/− , and Bak −/− /Bax −/− mice were obtained from Eileen White and were maintained in DMEM with antibiotics and 10% FBS 34 . C-terminal FLAG-tagged PIDD S588A mutant (mtPIDD) was obtained from the laboratory of Jürg Tschopp, cloned into pcDNA3.1 (+)/Hygro (Invitrogen), transfected into E1A+ cells and selected with hygromycin 15 , 32 . Cell lines were negative for mycoplasma contamination.…”
Expression of the adenovirus E1A oncogene sensitizes tumor cells to innate immune rejection by apoptosis induced by macrophage-produced tumor necrosis factor (TNF)-α and nitric oxide (NO). E1A sensitizes cells to TNF-α and NO through two distinct mechanisms, by repressing NF-κB-dependent antiapoptotic responses and enhancing caspase-2 activation and mitochondrial injury, respectively. The mechanisms through which E1A enhances caspase-2 activation in response to NO were unknown. Here, we report that E1A-induced sensitization to NO-induced apoptosis is dependent on expression of PIDD (p53-inducible protein with a death domain) and enhancement of primary immunodeficiency diseases (PIDD) processing for formation of the PIDDosome, the core component of the caspase-2 activation complex. NO-induced apoptosis in E1A-expressing cells did not require expression Bak or Bax, indicating that NO-induced caspase-2-mediated mitochondrial injury does not proceed through the activities of typical, proapoptotic Bcl-2 family members that induce mitochondrial cytochrome C release. These results define a PIDD-dependent pathway, through which E1A enhances casapse-2-mediated mitochondrial injury, resulting in increased sensitivity of mammalian cells to macrophage-induced, NO-mediated apoptosis.
“…Caspase 3 activation by Apoptin from both CAV and HGV has also been shown in a huge variety of cancer cell lines [92,93,[98][99][100]. NS1 and E1A expression is also sufficient to induce activation of caspase 3 [94,101]. Notably, caspase 3 is activated during the overexpression of E4orf4 in cancer cells but doesn't seem to be vital for the induction of cell death [97].…”
Cell death is a tightly regulated process which can be exploited in cancer treatment to drive the killing of the tumour. Several conventional cancer therapies including chemotherapeutic agents target pathways involved in cell death, yet they often fail due to the lack of selectivity they have for tumour cells over healthy cells. Over the past decade, research has demonstrated the existence of numerous proteins which have an intrinsic tumour-specific toxicity, several of which originate from viruses. These tumour-selective viral proteins, although from distinct backgrounds, have several similar and interesting properties. Though the mechanism(s) of action of these proteins are not fully understood, it is possible that they can manipulate several cell death modes in cancer exemplifying the intricate interplay between these pathways. This review will discuss our current knowledge on the topic and outstanding questions, as well as deliberate the potential for viral proteins to progress into the clinic as successful cancer therapeutics.
“…E1A is a promising candidate for cancer therapy, due to its proapoptotic [4], antiangiogenic [5,6], and chemosensitizing activities [7]. E1A is able to enhance the activity of a variety of proapoptotic stimuli, including chemotherapeutic agents and irradiation [8][9][10][11][12][13][14]. It was shown that the sensitizing effect of E1A on histone deacetylases inhibitors (HDACi) (e.g., SAHA, TSA) was stronger than the effect of the other chemotherapeutic drugs tested (5-fluorouracil, cisplatin, etoposide, paclitaxel) [12].…”
The adenoviral early region 1A (E1A) protein has proapoptotic and angiogenic activity, along with its chemosensitizing effect, making it the focus of increased interest in the context of cancer therapy. It was previously shown that E1A-induced chemosensitization to different drugs, including histone deacetylases inhibitors (HDACi), appears to be mediated by Forkhead box O (FoxO) transcription factors. In this study, we explore the relationship between E1A expression and the modulation of FoxO activity with HDACi sodium butyrate (NaBut). We show here that the basal FoxO level is elevated in E1A-expressing cells. Prolonged NaBut treatment leads to the inhibition of the FoxO expression and activity in E1A-expressing cells. However, in E1A-negative cells, NaBut promotes the transactivation ability of FoxO over time. A more detailed investigation revealed that the NaBut-induced decrease of FoxO activity in E1A-expressing cells is due to the NaBut-dependent decrease in E1A expression. Therefore, NaBut-induced inhibition of FoxO in E1A-positive cells can be overcome under unregulated overexpression of E1A. Remarkably, the CBP/p300-binding domain of E1Aad5 is responsible for stabilization of the FoxO protein. Collectively, these data show that the expression of E1A increases the FoxO stability but makes the FoxO level more sensitive to HDACi treatment.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
