Increased AR “expression” and “density” are basically interchangeable. Sometimes people also use “sensitivity” to mean the same thing, although technically there is a very slight difference.
The theory is that our androgen levels and/or androgen output/products (proteins made when AR system works appropriately) drop after exposure to 5ari’s, anti-androgens, etc.
Our body then compensates by increasing the amount of receptors (ARs) in order to try to get more of the endproduct made (proteins).
When we stop taking the 5ari’s or antiandrogens or whatever caused the drop in AR, you get a tital wave of androgens back in the system while the system still has high ARs. This basically nukes the AR system (too many AR endproducts/proteins). In response (I’m guessing here but potentially to mitigate cancer risk among other things), our body then silences the AR in certain tissues by adding something like a methyl group (there are a few other “things” our body can add to silence) so that no matter how high or low androgens or ARs go, it sort of doesnt matter since the gene itself is now silenced. So no more/way less endproducts/proteins being made = PFS.
Now, how does that fit into people’s stories that got PFS while still taking finasteride? They didn’t stop the medicine and then have that tidal wave. It could be complicated interactions with other medications or even stress responses (i.e. Glutathione and allopregnenelone are severely affected).
So to answer your question, a silneced gene means no protein being made. No protein being made means our body is increasing AR in order to try to get protein made. For some reason, our gene(s) are stuck silenced. Some type of faulty mechanism not allowing it to de-methylate. CRISPR seems like the most likely treatment method, although there is a chance that in time, the gene(s) could re-methylate.