778V Poster - 12. Physiology, metabolism and aging
Wednesday April 06, 4:00 PM - 7:00 PM

Authors:
Adel Alqarni; Martin Zeidler

Affiliation: University of Sheffield

Keywords:
t. other (drugs); u. drug discovery

Originally developed as a chemotherapy drug, MTX acts as an anti-folate by binding to and inhibiting di-hydrofolate reductase (DHFR) that is involved in the synthesis of nucleotides required for DNA damage repair and cellular proliferation. In the 1980’s, MTX was repurposed as a treatment for auto-inflammatory and auto-immune diseases such as rheumatoid arthritis at much lower doses. However, the mechanism of action of MTX as an anti-inflammatory agent has been unclear until 2015 when the Zeidler lab identified MTX as a JAK/STAT pathway inhibitor. While our insight suggests that MTX could be repurposed again to treat JAK/STAT associated diseases, concerns about potential mutagenic toxicities associated with its inhibition of DHFR have been raised.
My project uses Drosophila melanogaster to study the effects of low-dose MTX therapy, its potential mutagenic activity and its effects on JAK/STAT signaling in vivo. More broadly, I aim to examine the impact of MTX and to better understand the processes that modulate DNA damage and DNA-damage responses.
We have established an in vivo assay for DNA damage using w+; GMR-Gal4, UAS-white RNAi / + flies to report the frequency of DNA damage in cells of the developing fly eye. Using this assay, along with measures of lifespan, fecundity, chromatinization, and JAK/STAT pathway activity we have tested a range of MTX doses added into Drosophila food. The effects on survival, development and DNA damage phenotypes will be shown. My results indicate that that high drug concentrations result in low survival rates, fecundity and developmental defects as well as a significant increase in the rate of DNA damage. However, low doses of MTX do not affect survival or fecundity and surprisingly, show significant increases in lifespan and may even reduce the rate of DNA damage. Suggesting that reduced JAK/STAT pathway activity may be providing a benefit under these conditions.
In conclusion, while high doses of MTX lead to low survival and are mutagenic, low-doses may confer a survival and DNA-damage advantage. It will be interesting to establish whether these low-dose benefits are indeed linked to changes in JAK/STAT pathway activity in vivo. Latest results will be presented.