Abstract: ObjectiveTo evaluate the inhibitory effect of deuterium-depleted water (DDW) on the proliferation ofnasopharyngeal
carcinoma (NPC) cells in vitro and explore the possible mechanism. MethodsThe growth inhibition of NPC cells and
preosteoblast MC3T3-E1cells following DDW treatment was measured by MTT assay and plate colony formation assay. The
changes in migration and invasion of NPC cells were evaluated using Transwell and boyden chamber assays. The protein
expression of proliferating cell nuclear antigen (PCNA) was determined using Western blotting. Flow cytometry was
employed to evaluate the changes in cell cycle distribution after DDW treatment.ResultsDDW with deuterium concentrations
of100, 75and50ppm significantly suppressed the cell proliferation (P<0.05) and lowered colony formation capacity and
invasiveness of the NPC cells (P<0.01). Western blotting demonstrated a down-regulated expression of PCNA in the cells by
DDW. DDW also caused obvious cell cycle arrest in the NPC cells with reduced cells in S phase and significantly increased
cells in G1 phase (P<0.05). Rather than causing growth inhibition, DDW promoted the growth of normal control MC3T3-E1
cells.ConclusionDDW possesses selective biological effects to inhibit the proliferation of NPC cellsin vitro, suggesting the
potential of DDW as a novel nontoxic adjuvant therapeutic agent in antitumor therapy.