In comparison to regulate cells, overexpression of EpCAM led to inhibition of proliferation and migration in HMECs. This represents a regularly observed response of normal cells to an oncogenic stimulus. How ever, in contrast to results described for oncogenic ras or even the catalytic subunit of your telomerase we didn’t observe a comprehensive development arrest mediated by in duction of p16INK4A. EpCAM transfected HMECs are inhibited in cell proliferation, but do not undergo a terminal development arrest. This may be due to simultaneous upregulation and accumulation of p53 plus the cell cycle inhibitor p27Kip1. A crosstalk amongst EpCAM and p53 has by now been reported. EpCAM gene expression is downregulated by p53 and reduction of p53 results in greater EpCAM expression and a extra invasive phenotype in tumor cells. EpCAM didn’t have an effect on p53 or p27Kip1 gene transcrip tion, upregulations had been only noticeable around the protein level.
So, EpCAM may well induce improvements in p53 protein by affecting posttranscriptional modifications processes or protein stability. Furthermore, p27Kip1 is proven to inhibit Rho A driven cell migration processes. Consequently, our HMECs upregulating p27Kip1 immediately after EpCAM overexpression possibly showed an inhibition of cell mi gration in spite of down selleck regulation within the cell cell adhesion molecule E cadherin. Against our expectations, EpCAM expression alone didn’t directly impact transcription of other genes in our HMEC culture models, though a signaling pathway, right activated by EpCAM cleavage, has become previ ously described in pharyngeal cancer cells. Actually, in HEK293 and FaDu tumor cell lines EpCAM has been reported to act straight on transcription of c myc and cyclins. We transfected development arrested and po larized, too as proliferating HMEC cultures and per formed transcriptome analysis 24 h right after overexpression of EpCAM.
With this experimental approach we desired to determine early genes straight regulated by EpCAM, before induction within the transcription component p53 and its downstream genes. The two attempts gave no evidence that EpCAM overexpression is right affecting gene expres sion profile of HMECs. Our information indicate that no less than in main HMECs overexpression of EpCAM, with ab sence TAK-875 1000413-72-8 of other oncogenes or mutations, has no immedi ate and direct result on gene transcription. In truth, MCF10A, immortalized human epithelial cells owning inactivation within the INK4A gene locus, respond to EpCAM overexpression by upregulating c myc gene expression. So, we assume that other transforming stimuli really have to act together with EpCAM to induce changes on gene transcription level. The fact is, EpCAM is mainly acting on cell cell adhesion proteins such as E cadherin, claudins, tetraspanins and CD44.