Transcriptional response to serum stimulation of Rat1 fibroblasts in the presence or absence of the Myc interfering molecule termed Omomyc.. Rattus norvegicus

Myc is a multifaceted bHLHZip transcription factor deregulated in the majority of human cancers. How to target Myc for cancer therapy is unclear, given its involvement in a variety of key functions in healthy cells. We used microarrays to capture the cellular transcriptional response to Omomyc – a Myc interfering molecule acting at the level of protein protein interactions that demonstrated a remarkable therapeutic efficacy in transgenic mouse cancer models. We found that Omomyc differently affects Myc induced gene repression and activation, channelling the Myc interactome activity to repression. Overall design: To determine whether Omomyc causes widespread changes of the cell transcriptome, we analysed the transcriptional response to serum stimulation of Rat1 fibroblasts stably infected with an Omomer – Omomyc fused to the tamoxifen inducible oestrogen receptor ERTM – producing retrovirus (Rat1_Omomer) as compared to Rat1 cells infected with a control virus (Rat1_Control). Endogenous c-Myc is known to be sharply induced by serum and is critical for cell cycle re-entry. Cells were grown, serum-starved for 48 h in presence of tamoxifen (4-OHT) and stimulated by addition of fresh serum. Total RNA was collected from Rat1_Control and Rat1-Omomer cells at the time of serum re-addition (T0) and 90' thereafter (T90'), in the presence of tamoxifen.