We have developed an animal tumor model system to study the effects of c-Myc activation on apoptosis induction in vivo. Tumors were generated in SCID mice from Rat-1 fibroblasts that constitutively express an inactive c-Myc-estrogen receptor fusion protein (T.D. Littlewood et al, Nucleic Acids Res., 23: 1686 -1690, 1995), which is activated in vivo by the administration of 4-hydroxytamoxifen in...

Objective(s) Nonviral vector can be an attractive alternative to gene delivery in experimental study. In spite of some advantages in comparison with the viral vectors, there are still some limitations for efficiency of gene delivery in nonviral vectors. To determine the effective expression, the recombinant Escherichia coli lacZ genes were cloned into the different variants of pcDNA3.1 and the...

Lymphomagenesis in the presence of deregulated MYC requires suppression of MYC-driven apoptosis, often through downregulation of the pro-apoptotic BCL2L11 gene (Bim). Transcription factors (EBNAs) encoded by the lymphoma-associated Epstein-Barr virus (EBV) activate MYC and silence BCL2L11. We show that the EBNA2 transactivator activates multiple MYC enhancers and reconfigures the MYC locus to i...

We detected a rearrangement in the N-myc gene region in a neuroblastoma from a 9-month-old girl. In this case, the N-myc gene was amplified 50-fold in the primary tumor, the lymph node metastasis, and the hepatic metastasis. The rearrangement was detected only in the primary tumor and the lymph node metastasis, whereas N-myc RNA and protein expression were detected only in the primary tumor and...

We have developed an animal tumor model system to study the effects of c-Myc activation on apoptosis induction in vivo. Tumors were generated in SCIÃœmice from Rat-1 fibroblasts that constitutively express an inactive c-Myc-estrogen receptor fusion protein (T. D. Littlewood et al.. Nucleic Acids Res., 23: 1686-1690, 1995), which is activated in vivo by the admin istration of 4-hydroxytamoxifen ...

Oncogenic c-Myc renders cells sensitive to TRAIL-induced apoptosis, and existing data suggest that c-Myc sensitizes cells to apoptosis by promoting activation of the mitochondrial apoptosis pathway. However, the molecular mechanisms linking the mitochondrial effects of c-Myc to the c-Myc-dependent sensitization to TRAIL have remained unresolved. Here, we show that TRAIL induces a weak activatio...

Modulation of transcriptional elongation within the c-myc gene is thought to play a major role in determining levels of c-myc mRNA in both normal and tumor cells. A discrete site of blockage to transcriptional elongation has previously been localized at the 3' end of exon 1 of the mouse and human c-myc genes. We here identify an additional site of transcriptional attenuation that is located bet...

Murine ES cells can be maintained as a pluripotent, self-renewing population by LIF/STAT3-dependent signaling. The downstream effectors of this pathway have not been previously defined. In this report, we identify a key target of the LIF self-renewal pathway by showing that STAT3 directly regulates the expression of the Myc transcription factor. Murine ES cells express elevated levels of Myc an...

Transcriptional activation of the c-myc proto-oncogene is mediated by the transition of promoter proximal, paused RNA polymerase II (pol II) into a processive transcription mode. Using a transcription assay which allows the high resolution mapping of transcriptional complexes in intact nuclei, we have characterized the promoter proximal pause positions of pol II. Pol II paused in a nucleosome-f...