The pathogenesis of ovarian cancer remains to be elucidated. Our previous study demonstrated that myosin heavy chain 9 (MYH9) overexpression was associated with poor prognosis of epithelial ovarian cancer. However, the mechanism of MYH9 and its regulation by microRNA (miR) is not clear. The results of the present study demonstrated that miR-6089 was one of the microRNAs targeting MYH9, and miR-6089 overexpression suppressed ovarian cancer cell proliferation, migration, invasion and metastasis in vivo and in vitro. Mechanistic studies confirmed that miR-6089 directly targeted MYH9 to inactivate the Wnt/β-catenin signalling pathway and its downstream epithelial-to-mesenchymal transition (EMT), cell-cycle factors and c-Jun, whereas overexpression of MYH9 reversed the inhibitory effects of miR-6089 overexpression in ovarian cancer cells by upregulating the Wnt/β-catenin and its downstream EMT, cell-cycle factors and c-Jun. Interestingly, miR-6089 was transcriptionally inhibited by c-Jun, a transcription factor which could be induced by MYH9 via the Wnt/β-catenin pathway. Thus miR-6089/MYH9/β-catenin/c-Jun formed a negative feedback loop in ovarian cancer. In clinical samples, miR-6089 negatively correlated with MYH9 expression. Our study is the first to demonstrate that miR-6089 serves as a tumor-suppressive miRNA, and miR-6089/MYH9/β-catenin/c-Jun negative feedback loop inhibits ovarian cancer carcinogenesis and progression.

Background: Recent studies showed that macrophages co-cultured with ovarian cancer stem-like cells (OCSLCs) induced SKOV3 cell stemness via IL-8/STAT3 signaling. Genistein (GEN) demonstrates chemopreventive activity in inflammation-associated cancers. The present study aimed to examine whether and if GEN inhibits the stemness of SKOV3 and OVCA-3R cells induced by co-culture of THP-1 macrophages and SKOV3-derived OCSLCs. Methods: The co-culture was treated with or without different concentrations (10, 20, and 40 μmol/L) of GEN for 24 h. Depletion or addition of IL-8 in Co-CM and knockdown or overexpression of STAT3 in THP-1 macrophages was performed to demonstrate the possible associated mechanisms. The combined effects of GEN and STAT3 knockdown were examined with the nude mouse modle by co-injection of SKOV3-derived OCSLCs with THP-1 macrophages. Results: Our results showed that GEN down-regulated CD163 and p-STAT3 expression of THP-1 macrophage, decreased the levels of IL-10, increased the levels of IL-12 and nitric oxide (NO) in the conditioned medium, and reduced the clonogenic and sphere-forming capacities and the expression of CD133 and CD44 in SKOV3 cells induced by co-culture of THP-1 macrophages and OCSLCs in a dose-dependent manner. Moreover, depletion or addition of IL-8 enhanced or attenuated the effect of GEN. Additionally, knockdown or overepression of STAT3 in THP-1 macrophages potentiated or attenuated the inhibitory effects of GEN. Importantly, STAT3 overexpression retrieved the effects of IL-8 combined with GEN depletion on M2 polarization of THP-1 macrophages and stemness of SKOV3 cells induced by co-culture. The combination of GEN and STAT3 knockdown cooperatively inhibited the growth of tumors co-inoculated with OCSLCs/THP-1 macrophages in nude mice in vivo through blocking IL-8/STAT3 signaling. Conclusions: In summary, our findings suggested that GEN can inhibit the increased M2 polarization of macrophages and stemness of ovarian cancer cells by co-culture of macrophages with OCSLCs through disrupting IL-8/STAT3 signaling axis. This assisted GEN to be as a potential chemotherapeutic agent in human ovarian cancer.

TNF-α and TGF-β associated epithelial-mesenchymal transition (EMT) occurs via NF-κB-dependent transcriptional upregulation of Twist1.Chrysin (ChR) is a major active ingredient ofpropolis, which inhibits various cancer cells and possesses anti-inflammatory activities. This study aimed to assess whether and how ChR inhibits proinflammatory cytokine-induced EMT phenotype and cancer stem-like cell (CSLC) features in the HeLa cell line. HeLa cells were co-administered TNF-α (10.0 ng/mL) and TGF-β (5.0 ng/mL) for 24h following TGF-β (5.0 ng/mL) alone for 6 d in the presence or absence of ChR (5.0, 10.0 and 20.0μM). Then, the levels of EMT-related factors, multi-potential transcription factors, and stem cell markers were analyzed by immunoblot. Wound healing and tumor sphere formation assays were performed to assess the migration and self-renewal capabilities of cells, respectively. Overexpression and/or knockdown of NF-κBp65 and/or Twsit1 were used to explore the molecular mechanisms. The results showed that ChR inhibited EMT and CSLC properties in HeLa cells administered TNF-α after prolonged TGF-β treatment, in a concentration-dependent fashion. NF-κBp65 knockdown and ChR(10.0μM) cooperatively enhanced the inhibition of NF-κBp65 and Twist1 expression, EMT, and CSLC properties. Conversely, overexpression of NF-κBp65 combined with ChR(10.0μM) antagonized such activities. Meanwhile, Twist1silencing or overexpression combined with ChR treatment did not affect NF-κBp65 levels, but also reduced or enhanced EMT and CSLC properties. Importantly, overexpressing Twist1 combined with ChR reversed the effects of NF-κBp65 knockdown and ChR. ChR inhibits proinflammatory cytokine-induced EMT and CSLC features in HeLa cells by blocking the NF-κB/Twist axis.

Radiotherapy (RT) is a standard treatment strategy for many cancer types, but the need to frequently apply high doses of ionizing radiation in order to achieve therapeutic efficacy can cause severe harm to healthy tissues, leading to adverse patient outcomes. In an effort to minimize these toxic side effects, we herein sought to design a novel approach to the low-dose RT treatment of hypoxic tumors using a Tirapazamine (TPZ)-loaded exosome (EXO) nanoplatform (MT). This MT platform was synthesized via loading EXOs with TPZ, which is a prodrug that is activated when exposed to hypoxic conditions. MT application was able to achieve effective tumor inhibition at a relatively low RT dose (2 Gy) that was superior to standard high-dose (6 Gy) RT treatment with specific targeting to the hypoxic region of tumor. RT-mediated oxygen consumption further aggravated hypoxic conditions to improve TPZ activation and treatment efficacy. Together, our findings demonstrate the clinical promise of this MT platform as a novel tool for the efficient radiosensitization and treatment of cancer patients.