The voltage-dependent anion channel 1 (VDAC1), located at the outer mitochondrial membrane (OMM), is a key protein in regulating the exchange of ions, nucleotides and a variety of metabolites in and out of the mitochondria. As such, VDAC serves a crucial role in cellular energy maintenance. We have previously shown that silencing VDAC1 expression in T-Rex-293 cells by means of RNA interference using shRNA directed to human (h)VDAC1 resulted in reduced ATP production and a decrease in cell growth. Since cancer cells highly express VDAC, we examined here the effects of shRNA-hVDAC1-mediated silencing of VDAC1 expression on cancer cell growth in an animal model. To this end, HeLa cervical cancer cells were stably transfected with an inducible shRNA plasmid encoding for a sequence directed to hVDAC1. VDAC1 expression in these cells was decreased almost completely. Stably transfected shRNA-hVDAC1 HeLa cells proliferated much slower than did control cells, pointing to VDAC1 expression as being essential for normal growth of HeLa cancer cells. We further studied the ability of hVDAC1 silencing to block cancer cell proliferation in vivo. Nude mice subcutaneously inoculated with stably transfected shRNA-hVDAC1 HeLa cells developed about 40-fold smaller tumors than did mice inoculated with control HeLa cells. Taken together, the results of this study demonstrate, for the first time, the anticancer therapeutic potential of VDAC1 downregulation by means of shRNA.