CrowSan wrote:Is there any difference between sub-set of cell and original cell type?
There is if only a small number (or <100%) of the original cells expressed this marker.The cancer may well be hetrogenous in it's cellular profile from one cell to another. For example cells on the inside of the tumour/cancer (in vivo
) may have less nutrient/gas suppy so may be excreting factors to encourage new blood vessel growth, whilst cells on the outside of the tumour may be expressing markers/proteins regulated by their interaction with non-tumour cells. Thus (unless the cells you are working with are clonal) sub-sets can exist.
Also, removing cells from their 3D extra-cellular environment can easily change a whole host of gene expression profiles.
Imagine a gene that is up-regulated in response to a cytokine/growth factor released by surrounding stromal cells (such as fibroblasts which now seem to play a greater and greater role in cancer progression). Take the cancer cell away from this environment and this protein may just decrease with time. You may not even notice a decrease in the proliferation of the cancer cells in vitro
as the up-regulated gene X may have a role in cancer invasiveness (a metalo-protease or a collagenase for example).
The suggestion has already been raised here (and it was a good one) that you might want to examine the sequence of the protein/DNA that you have for homologous ones that have already been described. This will give (probably) the greatest clue as to its function in the absence of experimental data.
Let us know how you get on and good luck