Cationic liposomes (CLs) have been regarded as the most promising gene delivery vectors for decades with the advantages of excellent biodegradability, biocompatibility, and high nucleic acid encapsulation efficiency. However, the clinical use of CLs in cancer gene therapy is limited because of many uncertain factors in vivo. Extracellular barriers such as opsonization, rapid clearance by the reticuloendothelial system and poor tumor penetration, and intracellular barriers, including endosomal/lysosomal entrapped network and restricted diffusion to the nucleus, make CLs not the ideal vector for transferring extrinsic genes in the body. However, the obstacles in achieving productive therapeutic effects of nucleic acids can be addressed by tailoring the properties of CLs, which are influenced by lipid compositions and surface modification. This review focuses on the physiological barriers of CLs against cancer gene therapy and the effects of lipid compositions on governing transfection efficiency, and it briefly discusses the impacts of particle size, membrane charge density, and surface modification on the fate of CLs in vivo, which may provide guidance for their preclinical studies.

One cut homeobox 2 (ONECUT2 or OC‐2) is a newly discovered transcription factor. Aberrant expression of OC‐2 is closely related to cell proliferation, migration, invasion, and angiogenesis. In this study, we found that OC‐2 expression was upregulated in ovarian adenocarcinoma cells, by Western blot analysis. The results of immunohistochemistry showed that the expression of OC‐2 was also increased in malignant ovarian cancer tissue. In order to explore the role of OC‐2 in the development of ovarian cancer, siRNAs that specifically targets OC‐2 were designed. The siRNA targeting OC‐2 could effectively inhibit the vascular endothelial growth factor A (VEGFA) expression, but silence and overexpression of VEGFA did not affect OC‐2 expression. In addition, OC2‐siRNA could block the proliferation, migration, and invasion, and inhibit epithelial–mesenchymal transition and the AKT/ERK signaling pathway, of human ovarian cancer cells in vitro. In a mouse model of ovarian cancer xenograft tumors, OC2‐siRNA could significantly inhibit tumor cell growth and the tumor inhibition rate reached approximately 73%. The results of immunohistochemistry showed that the densities of microvessels stained with CD31, the expression of OC‐2 and VEGFA were significantly decreased in tumors. These data indicated that OC‐2 was an upstream regulator of VEGFA and silencing OC‐2 could inhibit ovarian cancer angiogenesis and tumor growth.

MiRNAs have emerged as a pivotal component of gene regulatory networks, mediating cytokines secretion, cell cycle, and differentiation regulation. However, how miRNAs collaborate with transcription factors and downstream effector proteins that determine the fate of ovarian cancer cells remains to be understood, especially regarding to mechanism of tumor angiogenesis regulation. Based on the qRT-PCR and IHC analysis, we found that miR-6086 was maintained a very low level both in ovarian cancer cell lines and tissues. Further, we identified OC2 and EGFL6 as the direct targets of miR-6086 by luciferase assay and we observed an inverse relationship between the expression of miR-6086 and the OC2/VEGFA/EGFL6 axis. The Western blotting analysis suggested that OC2 could directly upregulate VEGFA and indirectly up-regulate EGFL6 through VEGFA. Moreover, miR-6086 could indirectly downregulate VEGFA through OC2. In addition, miR-6086, siOC2 and siEGFL6 could negatively regulate the tumor growth and angiogenesis of ovarian cancer (Skov3) in the animal studies, with the inhibition rates of 77.07%, 69.89%, and 73.62%, respectively (**p < 0.01). Moreover, the tumor cell proliferation, migration, and invasion of ovarian cancer cell lines (Caov3 and Skov3) and vascular formation (HUVECs) were significantly suppressed in vitro, by decreasing the AKT/MAPK pathways (*p < 0.05). Taken together, our results reveal that miR-6086 can suppress the angiogenesis networks in ovarian cancer by down-regulating the OC2/VEGFA/EGFL6 axis, directly or indirectly, which may provide potential targets for tumor therapeutics.

Tumor angiogenesis plays an important role in the progression and metastasis of ovarian cancer. EGFL6 protein is highly expressed in ovarian cancer and has been proposed to play an important role in promoting tumor angiogenesis. Here, a CRISPR/Cas9 system was used to knockout the EGFL6 gene in the ovarian cancer cell line SKOV3, using specific guide RNA targeting the exons of EGFL6. The knockout of EGFL6 markedly inhibited the proliferation, migration, and invasion of SKOV3 cells, as well as promoted apoptosis of tumor cells. In the nude mouse model of ovarian cancer, knockout of EGFL6 remarkably inhibited tumor growth and angiogenesis. The transcript profile assays detected 4,220 differentially expressed genes in the knockout cells, including 87 genes that were correlated to proliferation, migration, invasion, and angiogenesis. Moreover, Western blotting confirmed that EGFL6 knockout downregulated the FGF-2/PDGFB signaling pathway. Thus, the results of this study indicated that EGFL6 could regulate cell proliferation, migration, and angiogenesis in ovarian cancer cells by regulating the FGF-2/PDGFB signaling pathway.

Detection of the biomarkers human epididymis protein 4 (HE4) and cancer antigen 125 (CA125) is an important parameter for ovarian cancer diagnosis and follow-up. For this reason, our study aimed to develop an immunological detection method for simultaneous detection of multiple ovarian cancer biomarkers based on a dual-signal system. The dual-signal system consists of quantum dot nanospheres (QDNBs) and fluorescent nanoparticles (FNPs) that emit different wavelengths of fluorescence under different excitation light. The HE4 and CA125 detection antibodies were conjugated with FNPs and QDNBs to form signal complexes, which produce a signal proportional to the concentration of HE4 and CA125. This dual-signal immunoassay was applied to human serum samples to detect HE4 and CA125 levels and compare them using an electrochemiluminescence (ECL) assay. The linear range of the assay was determined to be 1.25–20 ng mL⁻¹ for HE4, and 9.4–200 U mL⁻¹ for CA125. Comparison of 25 human serum samples subjected to the ECL assay resulted in impressive correlation coefficients of 0.91 and 0.96 for HE4 and CA125, respectively. A quantitative method for detecting HE4 and CA125 was successfully established. Preliminary clinical sample analysis showed that the dual-signal immunoassay has a strong clinical value in the screening and diagnosis of ovarian cancer.