The HSulf-1 (heparan sulfate 6-O-endosulfatase 1) gene is an important element that modulates the sulfation status of heparan sulfate proteoglycans (HSPGs), leading to the interference of HSPG-related signal transduction pathways. HSulf-1 plays a key role in regulating cell proliferation, tumorigenesis and angiogenesis. Recently, some studies have reported that HSulf-1 is a down-regulated gene in the majority of examined tumor types. In our present study, a recombinant plasmid DNA carrying HSulf-1-cDNA (pHSulf-1) was constructed. The antitumor effect of pHSulf-1 delivered by heparin-polyethyleneimine (HPEI) nanogels on human ovarian cancer and the possible mechanisms of the antitumor efficacy in vivo were further investigated. Heparin-polyethyleneimine (HPEI) nanogels, as a new safe non-viral gene delivery carrier, were prepared to deliver the plasmid expressing HSulf-1 into HSulf-1-deficient SKOV3 human ovarian cancer cells in vitro and in vivo. pHSulf-1 could be efficiently transfected into SKOV3 ovarian cancer cells by HPEI nanogels in vitro and in vivo. Stable expression of HSulf-1 in vitro and in vivo was verified by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. Furthermore, a SKOV3 intraperitoneal ovarian carcinomatosis model was established to investigate the growth inhibition function of pHSulf-1 in nude mice. Tumor weight was measured. An anti-angiogenesis effect of pHSulf-1 in vivo was detected by CD31 immunostaining and alginate-encapsulate tumor cell assay. Assessment of apoptotic cells and proliferation index in tumor tissues were performed by TUNEL assay and Ki‑67 immunostaining. Intraperitoneal injection of pHSulf-1/HPEI complexes efficiently reduced tumor weight by approximately 87% compared with control groups (P<0.01). Meanwhile, reduction in angiogenesis, inhibition of cell proliferation, as well as induction of tumor cell apoptosis were observed, without apparent systemic toxic effects. Collectively, these observations provide the first evidence that pHSulf-1 delivered by HPEI nanogels may become a promising therapeutic strategy against human ovarian cancer.

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