PT  - JOURNAL ARTICLE
AU  - Qian Wang
AU  - Yi F. Guan
AU  - Sarah E. Hancock
AU  - Kanu Wahi
AU  - Michelle van Geldermalsen
AU  - Blake K. Zhang
AU  - Angel Pang
AU  - Rajini Nagarajah
AU  - Blossom Mak
AU  - Lisa G. Horvath
AU  - Nigel Turner
AU  - Jeff Holst
TI  - Inhibition of guanosine monophosphate synthetase (GMPS) blocks glutamine metabolism and prostate cancer growth <em>in vitro</em> and <em>in vivo</em>
AID  - 10.1101/2020.09.07.286997
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.09.07.286997
4099  - http://biorxiv.org/content/early/2020/09/09/2020.09.07.286997.short
4100  - http://biorxiv.org/content/early/2020/09/09/2020.09.07.286997.full
AB  - Cancer cells increase their uptake of nutrients and metabolize them to provide the necessary building blocks for new cancer cells. Glutamine is a critical nutrient in cancer, however its contribution to purine metabolism in prostate cancer has not previously been determined. Guanosine monophosphate synthetase (GMPS) acts in the de novo purine biosynthesis pathway, utilizing a glutamine amide to synthesize the guanine nucleotide and replenish the purine pool in proliferative cancer cells. This study demonstrates that GMPS mRNA expression correlates with Gleason score in prostate cancer samples, while high GMPS expression was associated with decreased rates of overall and disease/progression-free survival. Pharmacological inhibition or knockdown of GMPS significantly decreased cell growth in both LNCaP and PC-3 prostate cancer cells. GMPS knockdown was rescued by addition of extracellular guanosine to the media, suggesting a direct effect on nucleotide synthesis. We utilized 15N-(amide)-glutamine and U-13C5-glutamine metabolomics to dissect the pathways involved, and intriguingly, despite similar growth inhibition by GMPS knockdown, we show unique metabolic effects across each cell line. PC-3 cells showed a build-up of purine precursors, as well as activation of purine salvage pathways highlighted by significant increases in guanine, adenosine, inosine and cytosine. Both cell lines exhibited increased levels of pyrimidines and prioritized TCA cycle in distinct ways to produce increased aspartate, another important purine precursor. Using a PC-3 xenograft mouse model, tumor growth was also significantly decreased after GMPS knockdown. These data further highlight the importance of glutamine metabolism for prostate cancer cell growth and provide support for GMPS as a new therapeutic target in prostate cancer.