Enhanced antitumor effects of follicle-stimulating hormone receptor-mediated hexokinase-2 depletion on ovarian cancer mediated by a shift in glucose metabolism.

BACKGROUND: Most cancers favor glycolytic-based glucose metabolism. Hexokinase-2 (HK2), the first glycolytic rate-limiting enzyme, shows limited expression in normal adult tissues but is overexpressed in many tumor tissues, including ovarian cancer. HK2 has been shown to be correlated with the progression and chemoresistance of ovarian cancer and could be a therapeutic target. However, the systemic toxicity of HK2 inhibitors has limited their clinical use. Since follicle-stimulating hormone (FSH) receptor (FSHR) is overexpressed in ovarian cancer but not in nonovarian healthy tissues, we designed FSHR-mediated nanocarriers for HK2 shRNA delivery to increase tumor specificity and decrease toxicity. RESULTS: HK2 shRNA was encapsulated in a polyethylene glycol-polyethylenimine copolymer modified with the FSH ß 33-53 or retro-inverso FSH ß 33-53 peptide. The nanoparticle complex with FSH peptides modification effectively depleted HK2 expression and facilitated a shift towards oxidative glucose metabolism, with evidence of increased oxygen consumption rates, decreased extracellular acidification rates, and decreased extracellular lactate and glucose consumption in A2780 ovarian cancer cells and cisplatin-resistant A2780CP counterpart cells. Consequently, cell proliferation, invasion and migration were significantly inhibited, and tumor growth was suppressed even in cisplatin-resistant ovarian cancer. No obvious systemic toxicity was observed in mice. Moreover, the nanoparticle complex modified with retro-inverso FSH peptides exhibited the strongest antitumor effects and effectively improved cisplatin sensitivity by regulating cisplatin transport proteins and increasing apoptosis through the mitochondrial pathway. CONCLUSIONS: These results established HK2 as an effective therapeutic target even for cisplatin-resistant ovarian cancer and suggested a promising targeted therapeutic approach.

Tumor-directed gene therapy in mice using a composite nonviral gene delivery system consisting of the piggyBac transposon and polyethylenimine.

BACKGROUND: Compared with viral vectors, nonviral vectors are less immunogenic, more stable, safer and easier to replication for application in cancer gene therapy. However, nonviral gene delivery system has not been extensively used because of the low transfection efficiency and the short transgene expression, especially in vivo. It is desirable to develop a nonviral gene delivery system that can support stable genomic integration and persistent gene expression in vivo. Here, we used a composite nonviral gene delivery system consisting of the piggyBac (PB) transposon and polyethylenimine (PEI) for long-term transgene expression in mouse ovarian tumors. METHODS: A recombinant plasmid PB [Act-RFP, HSV-tk] encoding both the herpes simplex thymidine kinase (HSV-tk) and the monomeric red fluorescent protein (mRFP1) under PB transposon elements was constructed. This plasmid and the PBase plasmid were injected into ovarian cancer tumor xenografts in mice by in vivo PEI system. The antitumor effects of HSV-tk/ganciclovir (GCV) system were observed after intraperitoneal injection of GCV. Histological analysis and TUNEL assay were performed on the cryostat sections of the tumor tissue. RESULTS: Plasmid construction was confirmed by PCR analysis combined with restrictive enzyme digestion. mRFP1 expression could be visualized three weeks after the last transfection of pPB/TK under fluorescence microscopy. After GCV admission, the tumor volume of PB/TK group was significantly reduced and the tumor inhibitory rate was 81.96% contrasted against the 43.07% in the TK group. Histological analysis showed that there were extensive necrosis and lymphocytes infiltration in the tumor tissue of the PB/TK group but limited in the tissue of control group. TUNEL assays suggested that the transfected cells were undergoing apoptosis after GCV admission in vivo. CONCLUSION: Our results show that the nonviral gene delivery system coupling PB transposon with PEI can be used as an efficient tool for gene therapy in ovarian cancer.

Retro-inverso follicle-stimulating hormone peptide-mediated polyethylenimine complexes for targeted ovarian cancer gene therapy.

BACKGROUND: The development of nanoparticle drug delivery systems with targeted ligands has the potential to increase treatment efficiency in ovarian cancer. METHODS: We developed a 21-amino acid peptide, YTRDLVYGDPARPGIQGTGTF (L-FP21) conjugated to polyethylenimine (PEI) and methoxy polyethylene glycol (mPEG) to prepare a nanoparticle drug vehicle to target follicle-stimulating hormone receptor (FSHR) in ovarian cancer. At the same time, we optimized the ligand of the nanoparticle vehicle using D-peptides, which consist of D-amino acids (D-FP21). Nanoparticle vehicles carrying the therapeutic gene plasmid growth-regulated oncogene alpha (pGRO-α) short hairpin RNA (shRNA) (FP21-PEG-PEI/pGRO-α) were prepared for further investigation. RESULTS: Compared with L-FP21, D-FP21 exhibited improved biological stability and higher uptake rate for FSHR-expressing ovarian cancer cells. The cytotoxicity of the L, D-FP21-PEG-PEI/pGRO-α complexes were significantly lower than that of the PEI/pGRO-α complex. The nanoparticle drug with the targeted ligand showed higher transfection efficiencies and improved anti-proliferation effects for ovarian cancer cells than that without the targeted ligand (mPEG-PEI/pGRO-α). Furthermore, an in vivo evaluation of an antitumor assay indicated that D-FP21-PEG-PEI/pGRO-α inhibited the growth of tumor spheroids considerably more than L-FP21-PEG-PEI/pGRO-α; their tumor inhibition rates were 58.5% and 33.3%, respectively. CONCLUSIONS: D-FP21-PEG-PEI/plasmid DNA is a safe and efficient gene delivery vehicle for ovarian cancer targeted therapy.

Targeted paclitaxel nanoparticles modified with follicle-stimulating hormone ß 81-95 peptide show effective antitumor activity against ovarian carcinoma.

The majority of patients with advanced ovarian cancer will experience a relapse and ultimately die from refractory diseases. Targeted therapy shows promise for these patients. Novel therapeutic strategies should be developed on the basis of the molecular mechanisms involved in ovarian cancer and the steroid hormone environment of ovaries. The ovary is the main target organ of follicle-stimulating hormone (FSH), which bind to its receptor with high affinity. In this study a FSH receptor-targeting ligand, FSH ß 81-95 peptide, was used as a targeting moiety to synthesize an FSH receptor-mediated drug delivery system. FSH ß 81-95 peptide-conjugated nanoparticles (FSH81-NPs) and paclitaxel-loaded FSH81-NPs (FSH81-NP-PTXs) were synthesized. In vitro studies showed that FSH ß 81-95 peptide enabled the specific uptake of cytotoxic drugs and increased the intracellular paclitaxel concentration in FSH receptor-expressing cancer cells, resulting in enhanced cytotoxic effects. In vivo studies showed that FSH81-NP-PTXs possessed higher antitumor efficacy against FSH receptor-expressing tumors without any clinical signs of adverse side effects or body weight loss due to modification with FSH ß 81-95 peptide. Therefore, FSH binding peptide-targeted drug delivery system exhibited high potential in the treatment of ovarian cancer, and tumor targeting via reproductive hormone receptors might improve the outcome of diseases.

Long-term in vivo biodistribution imaging and toxicity of polyacrylic acid-coated upconversion nanophosphors.

Rare-earth upconversion nanophosphors (UCNPs) have become one of the most promising classes of luminescent materials for bioimaging. However, there remain numerous unresolved issues with respect to the understanding of how these nanophosphors interact with biological systems and the environment. Herein, we report polyacrylic acid (PAA)-coated near-infrared to near-infrared (NIR-to-NIR) upconversion nanophosphors NaYF(4):Yb,Tm (PAA-UCNPs) as luminescence probes for long-term in vivo distribution and toxicity studies. Biodistribution results determined that PAA-UCNPs uptake and retention took place primarily in the liver and the spleen and that most of the PAA-UCNPs were excreted from the body of mice in a very slow manner. Body weight data of the mice indicated that mice intravenously injected with 15 mg/kg of PAA-UCNPs survived for 115 days without any apparent adverse effects to their health. In addition, histological, hematological and biochemical analysis were used to further quantify the potential toxicity of PAA-UCNPs, and results indicated that there was no overt toxicity of PAA-UCNPs in mice at long exposure times (up to 115 days). The study suggests that PAA-UNCPs can potentially be used for long-term targeted imaging and therapy studies in vivo.