After 8 hours of online-research I was unable to find any info at all..
I was able to get some concrete copy numbers of DNA (e.g. plasmid) per cell after transfection of diverse transfection techniques, but I was unable to get any concrete copy numbers of RNAs that correspond to the transgene (of any overexpression technique).
My main interest would be the hek293T overexpression RNA levels using the viral plasmid, but concrete RNA copy numbers from any possible overexpression technique would be of interest. (for human cells like Hela, Hek, HepG2..)
Ideally I would need a reputable source, but 'gut-feeling comments' are welcomed as well.
In the end I would like to compare overexpressed RNA concentrations to naturally extremely high concentrated endogenous RNAs. Are these levels comparable, or are the (viral) transgene promoters that much more effective?
EDIT: Please also mind that the nucleus is a strong barrier to foreign DNA. Might complicate this answer.