Do our results measuring mRNA gene expression with RT-PCR can reflect our results measuring protein expression by IHC? I would like to know if my results by RT-PCR should reflect that for IHC.
No. The mRNA levels that appeared abundant may yield low abundance protein. This is the result of post transcriptional regulations that affect the mRNAs before translated into protein.
I agree with the collegues, gene expression is tightly controlled by a number of post-transcriptional and post-translational mechanisms. Thus, to confirm your RT-PCR data you should also analyze protein expression by IHC.