Hematogenous Metastasis of Ovarian Cancer: Rethinking Mode of Spread

SummaryOvarian cancer has a clear predilection for metastasis to the omentum, but the underlying mechanisms involved in ovarian cancer spread are not well understood. Here, we used a parabiosis model that demonstrates preferential hematogenous metastasis of ovarian cancer to the omentum. Our studies revealed that the ErbB3-neuregulin 1 (NRG1) axis is a dominant pathway responsible for hematogenous omental metastasis. Elevated levels of ErbB3 in ovarian cancer cells and NRG1 in the omentum allowed for tumor cell localization and growth in the omentum. Depletion of ErbB3 in ovarian cancer impaired omental metastasis. Our results highlight hematogenous metastasis as an important mode of ovarian cancer metastasis. These findings have implications for designing alternative strategies aimed at preventing and treating ovarian cancer metastasis

2′-OMe-phosphorodithioate-modified siRNAs show increased loading into the RISC complex and enhanced anti-tumour activity

Improving small interfering RNA (siRNA) efficacy in target cell populations remains a challenge to its clinical implementation. Here, we report a chemical modification, consisting of phosphorodithioate (PS2) and 2′-O-Methyl (2′-OMe) MePS2 on one nucleotide that significantly enhances potency and resistance to degradation for various siRNAs. We find enhanced potency stems from an unforeseen increase in siRNA loading to the RNA-induced silencing complex, likely due to the unique interaction mediated by 2′-OMe and PS2. We demonstrate the therapeutic utility of MePS2 siRNAs in chemoresistant ovarian cancer mouse models via targeting GRAM domain containing 1B (GRAMD1B), a protein involved in chemoresistance. GRAMD1B silencing is achieved in tumours following MePS2-modified siRNA treatment, leading to a synergistic anti-tumour effect in combination with paclitaxel. Given the previously limited success in enhancing siRNA potency with chemically modified siRNAs, our findings represent an important advance in siRNA design with the potential for application in numerous cancer types

Metronomic docetaxel in PRINT nanoparticles and EZH2 silencing have synergistic antitumor effect in ovarian cancer

The purpose of this study was to investigate the antitumor effects of a combination of metronomic doses of a novel delivery vehicle, PLGA-PRINT nanoparticles containing docetaxel, and antiangiogenic mEZH2 siRNA incorporated into chitosan nanoparticles. In vivo dose-finding studies and therapeutic experiments were conducted in well-established orthotopic mouse models of epithelial ovarian cancer. Antitumor effects were determined on the basis of reduction in mean tumor weight and number of metastatic tumor nodules in the animals. The tumor tissues from these in vivo studies were stained to evaluate the proliferation index (Ki67), apoptosis index (cleaved caspase 3), and microvessel density (CD31). The lowest dose of metronomic regimen (0.5 mg/kg) resulted in significant reduction in tumor growth. The combination of PLGA-PRINT-docetaxel and CH-mEZH2 siRNA showed significant antitumor effects in the HeyA8 and SKOV3ip1 tumor models (P < 0.05). Individual as well as combination therapies showed significant antiangiogenic, antiproliferative, and proapoptotic effects, and combination therapy had additive effects. Metronomic delivery of PLGA-PRINT-docetaxel combined with CH-mEZH2siRNA has significant antitumor activity in preclinical models of ovarian cancer. (C) 2014 AACR

XPO1/CRM1 inhibition causes antitumor effects by mitochondrial accumulation of eIF5A

Purpose: XPO1 inhibitors have shown promise for cancer treatment, and yet the underlying mechanisms for the antitumor effects are not well understood. In this study, we explored the usefulness of selective inhibitors of nuclear export (SINE) compounds that are specific inhibitors of XPO1.Experimental Design: We used proteomic analysis in XPO1 inhibitor-treated ovarian cancer cell lines and examined antitumor effects in ovarian and breast cancer mouse models. We also studied the effects of XPO1 inhibitor in combination with chemotherapeutic agents.Results: XPO1 inhibitor treatment substantially increased the percentage of apoptotic cells (60%) after 72 hours of incubation. XPO1 inhibitor promoted the accumulation of eIF5A in mitochondria, leading to cancer cell death. Topotecan showed the greatest synergistic effect with XPO1 inhibitor. XPO1 inhibitors prevented the translocation of IGF2BP1 from the nucleus to the cytoplasm, thereby permitting the localization of eIF5A in the mitochondria. This process was p53, RB, and FOXO independent. Significant antitumor effects were observed with XPO1 inhibitor monotherapy in orthotopic ovarian (P < 0.001) and breast (P < 0.001) cancer mouse models, with a further decrease in tumor burden observed in combination with topotecan or paclitaxel (P < 0.05). This mitochondrial accumulation of eIF5A was highly dependent on the cytoplasmic IGF2BP1 levels.Conclusions: We have unveiled a new understanding of the role of eIF5A and IGF2BP1 in XPO1 inhibitor-mediated cell death and support their clinical development for the treatment of ovarian and other cancers. Our data also ascertain the combinations of XPO1 inhibitors with specific chemotherapy drugs for therapeutic trials. (C) 2015 AACR

Survival outcome of women with stage IV uterine carcinosarcoma who received neoadjuvant chemotherapy followed by surgery

Background and Objectives: To examine survival of women with stage IV uterine carcinosarcoma (UCS) who received neoadjuvant chemotherapy followed by hysterectomy. Methods: This is a nested case-control study within a retrospective cohort of 1192 UCS cases. Women who received neoadjuvant chemotherapy followed by hysterectomy based-surgery for stage IV UCS (n = 26) were compared to those who had primary hysterectomy-based surgery without neoadjuvant chemotherapy for stage IV UCS (n = 120). Progression-free survival (PFS) and cause-specific survival (CSS) were examined. Results: The most common regimen for neoadjuvant chemotherapy was carboplatin/paclitaxel (53.8%). Median number of neoadjuvant chemotherapy cycles was 4. PFS was similar between the neoadjuvant chemotherapy group and the primary surgery group (unadjusted-hazard ratio [HR] 1.19, 95% confidence interval [CI] 0.75-1.89, P = 0.45). Similarly, CSS was comparable between the two groups (unadjusted-HR 1.13, 95%CI 0.68-1.90, P = 0.64). When the types of neoadjuvant chemotherapy regimens were compared, women who received a carboplatin/paclitaxel regimen had better survival outcomes compared to those who received other regimens: PFS, unadjusted-HR 0.38, 95%CI 0.15-0.93, P = 0.027; and CSS, unadjusted-HR 0.21, 95%CI 0.07-0.61, P = 0.002. Conclusion: Our study found that there is no statistically significant difference in survival between women with stage IV UCS who are tolerated neoadjuvant chemotherapy and those who undergo primary surgery