Yes I believe its completely possible. A friend of mine has observed this phenomenon with respect to Wnt signaliing componenets in Colon Cancer

But one would suspect that there should be other factors involved to deliever one such effect.

Thank you Yoganathan. Can you please provide the reference on that? Does that microRNA has same target or different in perspective of oncogenesis/tumor suppression?

In his case, the targets appeared to be different because ectopic expression of the miR construct changed the levels of his protein of interest in one cell line, not the other. he has not published his work yet, am afraid. So I am unable to share more details, but its certain that another gene regulating the Wnt pathway is being regulated by the same microRNA..

We have not directly addressed that notion, but we see quite different effects of the same over-expressed miRNA in the same cell line depending on its activation status. Some similar observations had been reported miR-21 (Mol Cancer Res. 2010 Dec;8(12):1633-42. PMID: 21047769). Thus, give the possible genetic and epigentic alterations during progression from primary to metastatic tumors an altered effect of a given miRNA seems quite possible.

Thank you Prof. Becker for providing the reference of similar observation. Perhaps I'm observing similar effect in my experiment too.

Hi, Yoga......Talking about my work I guess. Now this is our medium of talk. Come to insti some day

Ruhul its quite possible that miRNA might act as Tumor suppressor or oncogene. All depends upon set of genes expressed and targetome expressed at that moment of time. What u can do take whole RNA at two different stages. Either perform micro array or NGS(better in this case). Later you can compare what other things are going between two different stages.

Best

Thank you Shabir for your suggestions. I'll try to do that.

I'm not an expert in this subject or nothing close, but since miRNAs act by pairing to mRNAs, and mRNAs can suffer modifications in their maturation, such as alternative splicing or editing, I guess it is quite possible. Since mRNA modifications differ among different activation states, or cell types, etc, the miRNA can be acting differently depending on the mRNA isoform that you find in that cell.

Bear in mind that these modifications (alternative splicing, editing) not only may alter the sequence to which the miRNA has to pair, but also to the stability of the mRNA target.