Any strtaegy that we can come up with, such as upregulating SIRT6 to deal with the problem will be much more unproven than using Lamivudine, which has been shown to -at least to some extent- accomplish the goal we are after.
Basically it comes to this: At the doses we likely need, what are the long term issues / risks associated with Lamivudine?
Upregulating SIRT6 seems like a very important part of any strategy because SIRT6 seems to be one of the main ways that LINE1 is inhibited. Another mechanism seems to be endogenous antisense promoter and RNA interference (see https://www.ncbi.nlm...les/PMC2875337/ for example).
Lamivudine is an analog of cytidine and therefore has the potential to cause major unintended problems if it is incorporated into DNA. It has been implicated in, itself, causing DNA damage (although primarily in vitro). There are numerous side effects, and it is unclear how much or if the suppression of the LINE1 reverse transcriptase outweighs these side effects long term.
In a search of the literature I was not so far able to find any discussion of dose-dependency of Lamivudine side effects. So even though the required dose for our purposes may be 50% or less than the standard dose of 150mg 2xd it's unclear how much better that would be.
This abstract is tantalizing, but I haven't been able to find any more details on it so far so I've asked the author if she can share some more information:
Characterizing small molecule inhibitors of the LINE1 endonuclease
https://www.fasebj.o...upplement.lb107
What we need is a small molecule which has a high selectivity and specificity to the LINE1 reverse transcriptase, and which therefore won't cause other problems. Lamivudine has neither of those, unfortunately.
Edited by smithx, 03 September 2019 - 06:54 PM.