For SC xenografts, HeLa-Luc cells were resuspended at 5 × 105 cells/200 μl of 20% matrigel in PBS. This 200 μl solution containing cells and matrigel was injected SC into the hind leg/lower back region of mice. SC xenografts were allowed to grow for 2 weeks in mice before treatments commenced. Mice were given a total of six intratumoral injections of 20 μg of DNA plasmid combined with 3.2 μl of in vivo-jetPEIin 100 μl of 5% glucose over a period of 28 days (N/P ratio of 8). For IP xenografts, HeLa or HeLa-Luc cells were resuspended at 5 × 105 cells/500 μl of PBS. Mice were injected twice with 250 μl of this cell solution into the lower right and lower left peritoneum to facilitate even dispersal of the 5 × 105 cells throughout the abdominal region. IP xenografts were allowed to grow 1 week before the start of the treatment. Mice were given a total of six IP injections of 100 μg of DNA combined with 16 μl of in vivo-jetPEI in 500 μl of 5% glucose over a period of 15 days (N/P ratio of 8).

Rad51 protein is overexpressed in a wide range of human cancers. Our previous in vitro studies demonstrated that a construct comprised Rad51 promoter driving expression of the diphtheria toxin A gene (pRad51-diphtheria toxin A (DTA)) destroys a variety of human cancer cell lines, with minimal to no toxicity to normal human cells. Here we delivered Rad51 promoter-based constructs in vivo using linear polyethylenimine nanoparticles, in vivo jetPEI, to visualize and treat tumors in mice with HeLa xenografts. For tumor detection, we used pRad51-Luc, a construct containing the firefly luciferase under the Rad51 promoter, administered by intraperitoneal (IP) injection. Tumors were detected with an in vivo bioluminescent camera. All mice with cancer displayed strong bioluminescence, while mice without cancer displayed no detectable bioluminescence. Treatment with pRad51-DTA/jetPEI decreased tumor mass of subcutaneous (SC) and IP tumors by sixfold and fourfold, respectively, along with the strong reduction of malignant ascites. Fifty percent of the mice with SC tumors were cancer-free after six pRad51-DTA/jetPEI injections, and for the mice with IP tumors, mean survival time increased by 90% compared to control mice. This study demonstrates the clinical potential of pRad51-based constructs delivered by nanoparticles for the diagnostics and treatment of a wide range of cancers.