Systemic deuteration of SCID mice using the water‐isotopologue deuterium oxide (D2O) inhibits tumor growth in an orthotopic bioluminescent model of human pancreatic ductal adenocarcinoma

Abstract

AbstractSince its initial discovery as a natural isotopologue of dihydrogen oxide (1H2O), extensive research has focused on the biophysical, biochemical, and pharmacological effects of deuterated water (2H2O [D2O, also referred to as “heavy water”]). Using a panel of cultured human pancreatic ductal adenocarcinoma (PDAC) cells we have profiled (i) D2O‐induced phenotypic antiproliferative and apoptogenic effects, (ii) redox‐ and proteotoxicity‐directed stress response gene expression, and (iii) phosphoprotein‐signaling related to endoplasmic reticulum (ER) and MAP‐kinase stress response pathways. Differential array analysis revealed early modulation of stress response gene expression in both BxPC‐3 and PANC‐1 PDAC cells elicited by D2O (90%; ≤6 h; upregulated: HMOX1, NOS2, CYP2E1, CRYAB, DDIT3, NFKBIA, PTGS1, SOD2, PTGS2; downregulated: RUNX1, MYC, HSPA8, HSPA1A) confirmed by independent RT‐qPCR analysis. Immunoblot‐analysis revealed rapid (≤6 h) onset of D2O‐induced MAP‐kinase signaling (p‐JNK, p‐p38) together with ER stress response upregulation (p‐eIF2α, ATF4, XBP1s, DDIT3/CHOP). Next, we tested the chemotherapeutic efficacy of D2O‐based drinking water supplementation in an orthotopic PDAC model employing firefly luciferase‐expressing BxPC‐3‐FLuc cells in SCID mice. First, feasibility and time course of systemic deuteration (30% D2O in drinking water; 21 days) were established using time‐resolved whole‐body proton magnetic resonance imaging and isotope‐ratio mass spectrometry‐based plasma (D/H)‐analysis. D2O‐supplementation suppressed tumor growth by almost 80% with downregulated expression of PCNA, MYC, RUNX1, and HSP70 while increasing tumor levels of DDIT3/CHOP, HO‐1, and p‐eIF2α. Taken together, these data demonstrate for the first time that pharmacological induction of systemic deuteration significantly reduces orthotopic tumor burden in a murine PDAC xenograft model.