Correction: Targeting Leptin as a Therapeutic Strategy against Ovarian Cancer Peritoneal Metastasis.

The authors would like to correct Fig. 1, Fig. 3 and Fig. 5G, as errors were introduced in the preparation of these figures for publication. The authors declare that these corrections do not change the results or conclusions of this paper. We sincerely apologize for having this error in the article, and apologize for any inconvenience caused. The authors have provided corrected version of Fig. 1, Fig. 3 and Fig. 5G here.

Heterotypic CAF-tumor spheroids promote early peritoneal metastatis of ovarian cancer.

High-grade serous ovarian cancer (HGSOC) is hallmarked by early onset of peritoneal dissemination, which distinguishes it from low-grade serous ovarian cancer (LGSOC). Here, we describe the aggressive nature of HGSOC ascitic tumor cells (ATCs) characterized by integrin α5high (ITGA5high) ATCs, which are prone to forming heterotypic spheroids with fibroblasts. We term these aggregates as metastatic units (MUs) in HGSOC for their advantageous metastatic capacity and active involvement in early peritoneal dissemination. Intriguingly, fibroblasts inside MUs support ATC survival and guide their peritoneal invasion before becoming essential components of the tumor stroma in newly formed metastases. Cancer-associated fibroblasts (CAFs) recruit ITGA5high ATCs to form MUs, which further sustain ATC ITGA5 expression by EGF secretion. Notably, LGSOC is largely devoid of CAFs and the resultant MUs, which might explain its metastatic delay. These findings identify a specialized MU architecture that amplifies the tumor-stroma interaction and promotes transcoelomic metastasis in HGSOC, providing the basis for stromal fibroblast-oriented interventions in hampering OC peritoneal propagation.

Expression of ADAMTS13 in Normal and Abnormal Placentae and Its Potential Role in Angiogenesis and Placenta Development.

OBJECTIVE: ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 repeats, member 13) is primarily synthesized in liver. The biosynthesis of ADAMTS13 and its physiological role in placenta are not known. APPROACH AND RESULTS: We used real-time polymerase chain reaction, immunohistochemistry, and Western blotting analyses, as well as proteolytic cleavage of FRETS (fluorescent resonance energy transfers)-VWF73, to determine ADAMTS13 expression in placenta and trophoblasts obtained from individuals with normal pregnancy and patients with severe preeclampsia. We also determined the role of ADAMTS13 in extravillous trophoblasts using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, wound scratch assay, transwell migration assay, tube formation assay, and tissue outgrowth assays. We showed that full-length and proteolytically active ADAMTS13 was expressed in normal human placenta, primarily in the trophoblasts and villous core fetal vessel endothelium during pregnancy. Placental expression of ADAMTS13 mRNA, protein, and proteolytic activity was at the highest levels during the first trimester and significantly reduced at the term of gestation. Additionally, significantly reduced levels of placental ADAMTS13 expression was detected under hypoxic conditions and in patients with preeclampsia. In addition, recombinant ADAMTS13 protease stimulated proliferation, migration, invasion, and network formation of trophoblastic cells in culture. Finally, knockdown of ADAMTS13 expression attenuated the ability of tube formation in trophoblast (HTR-8/SVNEO) cells and the extravillous trophoblast outgrowth in placental explants. CONCLUSIONS: Our results demonstrate for the first time the expression of ADAMTS13 mRNA and protein in normal and abnormal placental tissues and its role in promoting angiogenesis and trophoblastic cell development. The findings support the potential role of the ADAMTS13-von Willebrand factor pathway in normal pregnancy and pathogenesis of preeclampsia.

Targeting Leptin as a Therapeutic Strategy against Ovarian Cancer Peritoneal Metastasis.

BACKGROUND/AIMS: Epithelial ovarian cancer (OC) is the leading cause of death in patients with gynecologic malignancy. Malignant ascites, a shared symptom of advanced OC patients, plays an important role in the peritoneal metastasis cascade of OC. Since leptin existed in great amount in malignant ascites, we speculated that it might be involved in the modulation of tumor cells malignant behavior. METHOD: Here, we demonstrated that blocking of leptin could significantly suppress ovarian malignant ascitesinduced metastatic aggravation of OC cells. Furthermore, our results suggested that leptin was highly expressed in OC and correlated with poor outcome of OC patients. Recombinant leptin notably promoted the migration, invasion and proliferation of OC cells. RESULT: Mechanistically, we found that leptin induced epithelial-mesenchymal transition (EMT) program in OC cells through the activation of the PI3K/Akt/mTOR pathway. Pharmacological inhibition of the PI3K/Akt/mTOR pathway partly impaired leptin-induced malignant transformation of OC cells. More importantly, our in vivo xenograft experiment showed that blocking of leptin could dramatically inhibit OC cells peritoneal dissemination. CONCLUSION: Collectively, this study emphasized the importance of leptin in OC progression and illustrated a novel mechanism that the PI3K/Akt/mTOR pathway was involved in leptin-induced EMT. Our findings provide new insights into leptin exertion on OC metastasis and identify the potential of leptin neutralizing as a novel strategy against OC peritoneal dissemination.

Quercetin induces endoplasmic reticulum stress to enhance cDDP cytotoxicity in ovarian cancer: involvement of STAT3 signaling.

There is an urgent need to make cisplatin (cDDP) more effective and less toxic in the treatment of ovarian cancer for its systemic side effects and high resistance rate. In this study, we investigated the effect of quercetin (Qu) pretreatment on the potentiation of cDDP in ovarian cancer. We found that Qu pretreatment significantly enhanced cDDP cytotoxicity in an ovarian cancer cell line and primary cancer cells. In addition, we demonstrated that Qu elicited obvious endoplasmic reticulum stress (ERS) and activated all three branches of ERS in ovarian cancer. Specific inhibitors of each ERS pathway, as well as the general ERS stabilizer tauroursodeoxycholic acid, notably diminished such enhancing effects. Furthermore, Qu notably suppressed STAT3 phosphorylation, leading to downregulation of the BCL-2 gene downstream of STAT3. Moreover, blocking ERS restored the protein levels of phosphorylated STAT3 as well as BCL-2 expression, thus abolishing the chemosensitization potency of Qu; these results revealed that Qu affected the STAT3 pathway to enhance cDDP cytotoxicity, and this effect involved ERS signaling. In a xenograft mouse model of ovarian cancer, Qu enhanced the antitumor effect of cDDP. Tumors from mice treated with cDDP in combination with Qu pretreatment had repressed STAT3 phosphorylation, lower BCL-2 and higher apoptosis levels compared with those from the other groups. Meanwhile, Qu markedly reduced the elevation of blood creatinine during cDDP intervention. These data indicate that Qu pretreatment potentiates the antitumor effects of cDDP in ovarian cancer while protecting the kidneys against damage. Therefore the strategy of Qu pretreatment may be beneficial in enhancing the therapeutic efficacy of cDDP against ovarian cancer.

Co-targeting EGFR and Autophagy Impairs Ovarian Cancer Cell Survival during Detachment from the ECM.

Ovarian cancer (OC) remains the most aggressive and lethal gynecological tumor characterized by massive intraperitoneal dissemination and malignant ascites. The carcinoma cells exfoliated from the primary tumor and were further transformed in the ascites microenvironment. During this suspension process, multi-cellular spheroids are formed and these aggregates represent an invasive and chemoresistant cellular population fundamental to metastatic dissemination. Activation of EGFR signaling is involved in increased cell metastasis and decreased apoptosis of ovarian cancer. The application of EGFR Inhibition in ovarian cancer was hampered for its limited benefit as a solitary therapy. In this work, our results primarily indicated that autophagy was induced in response to EGFR specific inhibitor AG1478 in OC cell lines generated spheres and ascites primary spheroids, characterized by the elevation of LC3-II, Beclin1 and Atg5. Blockage of autophagy with 3MA notably promoted spheroid death in suspension as well as AG1478-induced cell apoptosis, suggesting a protective autophagy contribution during tumor cells in suspension or under EGFR inhibition. Consequently, inhibiting autophagy with 3MA significantly enhanced the inhibitory effect of AG1478 on tumor cell peritoneal propagation in SKOV3 i.p. xenografts model. In addition, elevated EGFR, Beclin1, and Atg5 mRNA levels were associated with decreased ovarian cancer patient survival. Together, our findings suggested that targeting autophagy held the potential to improve EGFR inhibition benefit in the treatment of ovarian cancer cells during detachment from the extra-cellular matrix (ECM), and that this combination strategy might provide a new treatment option in controlling peritoneal metastasis of ovarian cancer.

Activation of integrin ß1 mediates the increased malignant potential of ovarian cancer cells exerted by inflammatory cytokines.

Epithelial ovarian cancer (EOC) is a highly lethal gynecological malignancy since it could not be discovered until at late stage. Identifying the molecular phenotype alteration during the development and progression of ovarian cancer is an urgent demand for the targeted intervention therapy. Recently, inflammation and Integrin beta 1(ITGB1), a subunit of heterodimeric transmembrane receptors family, had been pointed out to be involved in promoting ovarian tumorigenesis and cancer progression, respectively. However, the relationship between ITGB1 and the inflammatory mediators in ovarian cancer progression remains obscure. In the present study, ITGB1 was observed to be frequently upregulated in ovarian cancer, overexpression of ITGB1 led to a more invasive and mesenchymal phenotype. Furthermore, our results also provided evidence concerning the role of inflammatory cytokines (IL-6, TGF-ß1 and SDF-1) in ITGB1 expression as well as in the malignant potential of ovarian cancer cells. Consistently, sh-RNA mediated knocking down of ITGB1 evidently reduced tumor growth and peritoneal dissemination in in vivo Nod-scid SKOV3 orthotopic xenograft mice. Overall, the present data suggested that ITGB1 upregulation was involved in the regulation of tumorigenesis and disease exacerbation exerted by inflammatory cytokines as IL-6, TGF-ß1 and SDF-1, and suggested that targeting ITGB1 and the underlying inflammatory modulator was an attractive strategy for therapeutic intervention during ovarian carcinogenesis.