A novel antidiuretic hormone governs tumour-induced renal dysfunction.

Maintenance of renal function and fluid transport are essential for vertebrates and invertebrates to adapt to physiological and pathological challenges. Human patients with malignant tumours frequently develop detrimental renal dysfunction and oliguria, and previous studies suggest the involvement of chemotherapeutic toxicity and tumour-associated inflammation 1,2 . However, how tumours might directly modulate renal functions remains largely unclear. Here, using conserved tumour models in Drosophila melanogaster 3 , we characterized isoform F of ion transport peptide (ITP F ) as a fly antidiuretic hormone that is secreted by a subset of yki 3SA gut tumour cells, impairs renal function and causes severe abdomen bloating and fluid accumulation. Mechanistically, tumour-derived ITP F targets the G-protein-coupled receptor TkR99D in stellate cells of Malpighian tubules-an excretory organ that is equivalent to renal tubules 4 -to activate nitric oxide synthase-cGMP signalling and inhibit fluid excretion. We further uncovered antidiuretic functions of mammalian neurokinin 3 receptor (NK3R), the homologue of fly TkR99D, as pharmaceutical blockade of NK3R efficiently alleviates renal tubular dysfunction in mice bearing different malignant tumours. Together, our results demonstrate a novel antidiuretic pathway mediating tumour-renal crosstalk across species and offer therapeutic opportunities for the treatment of cancer-associated renal dysfunction.