Fig. 7: KISS1R expression promotes purine synthesis.

a Diagram of the purine synthesis pathway, including the amide nitrogen glutamine tracer. Diamonds indicate nitrogen, labeled for amide (red) and unlabeled (white). Diamond with subscript α denotes the alpha nitrogen of glutamine. Fractional enrichment of glutamine’s amide nitrogen contributing to metabolites in purine synthesis in SKBR3FLAG-KISS1R and pFLAG control cells (n = 3): b IMP, c ATP, and d 5-methylthioadenosine. Metabolite levels in orthotopic primary tumors of e 5-methylthioadenosine and f xanthosine-5′-phosphate and g serum guanosine levels in SKBR3FLAG-KISS1R and SKBR3pFLAG control xenografts (n = 4 mice for FLAG-KISS1R xenografts; n = 3 for pFLAG controls). Mean ± SEM shown. *p < 0.05, Student’s unpaired t test.