Purpose Jagged1, a Notch ligand, is expressed on both tumor epithelial and endothelial cells, and therefore may be amenable to dual targeting of the tumor stroma and malignant cell compartments of the tumor microenvironment. Experimental Design We describe in vitro effects of targeting of Jagged1 on ovarian cancer cells and in vivo effects of independent targeting of stromal and malignant cell Jagged1 using species-specific human or murine siRNA constructs incorporated into chitosan nanoparticles (CH) and delivered intravenously in an orthotopic mouse model. Results Jagged1 expression was prominent in SKOV3ip1, and IGROV-AF1, and significantly overexpressed in SKOV3TRip2, a taxane-resistant SKOV3 subclone. Jagged1 silencing with siRNA decreased cell viability and reversed taxane chemoresistance. In two different orthotopic ovarian cancer models, treatment with anti-human Jagged1 siRNA-CH reduced growth by 54.4-58.3%, and with anti-murine Jagged1 siRNA-CH reduced growth by 41.7-48.8%. The combination of both species-specific constructs reduced tumor weight by 87.5-93.1% and sensitized SKOV3TRip2 tumors to docetaxel in vivo. Tumors demonstrated reduced microvessel density with anti-murine Jagged1 constructs, and decreased proliferation with anti-human Jagged1 siRNAs-CH. In addition, we show that Jagged1 downregulation does not sensitize cells to taxanes through a reduction in MDR1 expression, but at least in part by crosstalk with the GLI2 mediator of the Hedgehog pathway. Conclusions Jagged1 plays dual roles in cancer progression, through an angiogenic function in tumor endothelial cells, and through proliferation and chemoresistance in tumor cells. Dual inhibition represents an attractive therapeutic strategy for ovarian and potentially other malignancies.

Overcoming drug-resistance is a big challenge to improve the survival of patients with epithelial ovarian cancer (EOC). In this study, we investigated the effect of chloroquine (CQ) and its combination with cisplatin (CDDP) in drug-resistant EOC cells. We used the three EOC cell lines CDDP-resistant A2780-CP20, RMG-1 cells, and CDDP-sensitive A2780 cells. The CQ-CDDP combination significantly decreased cell proliferation and increased apoptosis in all cell lines. The combination induced expression of γH2AX, a DNA damage marker protein, and induced G2/M cell cycle arrest. Although the CQ-CDDP combination decreased protein expression of ATM and ATR, phosphorylation of ATM was increased and expression of p21WAF1/CIP1 was also increased in CQ-CDDP-treated cells. Knockdown of p21WAF1/CIP1 by shRNA reduced the expression of γH2AX and phosphorylated ATM and inhibited caspase-3 activity but induced ATM protein expression. Knockdown of p21WAF1/CIP1 partly inhibited CQ-CDDP-induced G2/M arrest, demonstrating that knockdown of p21WAF1/CIP1 overcame the cytotoxic effect of the CQ-CDDP combination. Ectopic expression of p21WAF1/CIP1 in CDDP-treated ATG5-shRNA/A2780-CP20 cells increased expression of γH2AX and caspase-3 activity, demonstrating increased DNA damage and cell death. The inhibition of autophagy by ATG5-shRNA demonstrated similar results upon CDDP treatment, except p21WAF1/CIP1 expression. In an in vivo efficacy study, the CQ-CDDP combination significantly decreased tumor weight and increased expression of γH2AX and p21WAF1/CIP1 in A2780-CP20 orthotopic xenografts and a drug-resistant patient-derived xenograft model of EOC compared with controls. These results demonstrated that CQ increases cytotoxicity in combination with CDDP by inducing lethal DNA damage by induction of p21WAF1/CIP1 expression and autophagy inhibition in CDDP-resistant EOC.

MicroRNAs 渊miRNAs冤 are a class of highly abundant non鄄 coding RNA molecules that are involved in several biological processes. Many miRNAs are often deregulated in several diseases including cancer.There is substantial interest in exploiting miRNAs for therapeutic applications. In this editorial, we briefly review current advances in the use of miRNAs or antisense oligonucleotides (antagomirs) for such therapies. One of the key issues related to therapy using miRNAs is degradation of naked particles in vivo. To overcome this limitation, delivery systems for miRNA鄄 based therapeutic agents have been developed, which hold tremendous potential for improving therapeutic outcome of cancer patients.

No abstract