Mixed lineage leukemia 5 (MLL5) protein is a trithorax family histone 3 lysine 4 (H3K4) methyltransferase that regulates diverse biological processes, including cell cycle progression, hematopoiesis and cancer. The mechanisms by which MLL5 protein stability is regulated have remained unclear to date. Here, we showed that MLL5 protein stability is cooperatively regulated by O-GlcNAc transferase (OGT) and ubiquitin-specific protease 7 (USP7). Depletion of OGT in cells led to a decrease in the MLL5 protein level through ubiquitin/proteasome-dependent proteolytic degradation, whereas ectopic expression of OGT protein suppressed MLL5 ubiquitylation. We further identified deubiquitinase USP7 as a novel MLL5-associated protein using mass spectrometry. USP7 stabilized the MLL5 protein through direct binding and deubiquitylation. Loss of USP7 induced degradation of MLL5 protein. Conversely, overexpression of USP7, but not a catalytically inactive USP7 mutant, led to decreased ubiquitylation and increased MLL5 stability. Co-immunoprecipitation and co-immunostaining assays revealed that MLL5, OGT and USP7 interact with each other to form a stable ternary complex that is predominantly located in the nucleus. In addition, upregulation of MLL5 expression was correlated with increased expression of OGT and USP7 in human primary cervical adenocarcinomas. Our results collectively reveal a novel molecular mechanism underlying regulation of MLL5 protein stability and provide new insights into the functional interplay among O-GlcNAc transferase, deubiquitinase and histone methyltransferase.

Ovarian cancer has the highest mortality rate of the gynaecological cancers. Although cisplatin (CDDP) is an effective treatment for ovarian cancer, recurrence is frequent and leads to death. The objective was to explore the role and possible mechanisms of platelet-activating factor receptor (PAFR) signalling in CDDP-treated ovarian cancer cells. The upregulation of PAFR in CDDP-treated ovarian cancer cells was observed using realtime PCR and Western blot. The potential role of PAFR in modulating the CDDP sensitivity was assessed using a pharmacological inhibitor and siRNA knockdown. The PAFR-activated signalling pathways involved in cell responses to CDDP were assessed. Cisplatin induced increased PAFR expression in two ovarian cancer cell lines. The upregulation of PAFR by CDDP correlated with the time-dependent accumulation of NF-κB and HIF-1α in the nucleus. The inhibition of PAFR sensitised the ovarian cancer cells to CDDP. The PI3K and ERK pathways lie downstream of activated PAFR in CDDP-treated cells and their inhibition enhanced CDDP sensitivity. Finally, co-treatment with a PAFR antagonist (Ginkgolide B) and CDDP markedly reduced tumour growth in an in vivo model of ovarian cancer. Together, these findings suggest that PAFR is a novel and promising therapeutic target for sensitising ovarian cancer cells to CDDP.

The tumour microenvironment conferred by mesenchymal stem cells (MSCs) plays a key role in tumour development and progression. We previously determined that platelet-activating factor receptor (PAFR) was overexpressed in ovarian cancer cells (OCCs) and that PAF can promote ovarian cancer progression via PAF/PAFR-mediated inflammatory signalling pathways. Evidence suggests that MSCs can secrete high concentrations of PAF. Here, we investigated the role of PAF/PAFR signalling in the microenvironment mediated by MSCs and OCCs and its effect on cancer progression. The PAF concentrations in the culture media of MSCs, OCCs and co-cultured MSCs and OCCs were determined by ELISA. The effects of MSCs on OCCs in vitro were assessed on cells treated with conditioned medium (CM). The expression and phosphorylation of key proteins in the PAF/PAFR signalling pathway were evaluated. In vivo, MSCs/RFP and SKOV3 cells were co-administered at different proportions to nude mice by interscapular injection. Mice in the WEB2086 group were intraperitoneally injected with the PAFR antagonist WEB2086 at a dose of 1 mg/kg.d for the duration of the animal experiments. Tumour progression was observed, and the weight and survival time of mice were measured. The PAF concentration in peripheral and tumour site blood was determined by ELISA. High concentrations of PAF were detected in CM from MSCs and MSCs co-cultured with OCCs. Both types of medium promoted non-mucinous OCC proliferation and migration but had no effect on mucinous-type OCCs. These effects could be blocked by PAFR inhibitors. The expression and phosphorylation of key proteins in the PAF/PAFR pathway significantly increased upon treatment with PAF and MSC-CM. In vivo, the tumour volume was larger following co-injection of SKOV3 cells and MSCs/RFP than following injection of SKOV3 cells alone. The tumour-promoting effect of MSCs/RFP was blocked by the PAFR antagonist WEB2086. Serum PAF concentrations significantly increased in co-injected mice. Our results suggest that the tumour-promoting effect of MSCs on OCCs via their cross-talk in the tumour microenvironment was, at least in part, mediated by the PAF/PAFR pathway, suggesting a new target for the treatment of ovarian cancer.

Genetic alterations, including the overexpression of epidermal growth factor receptor (EGFR), play a crucial role in ovarian carcinogenesis. To date, EGFR targeting has shown limited antitumor effects in ovarian cancer when administered as monotherapy. We previously identified platelet-activating factor receptor (PAFR) as being overexpressed in ovarian cancer and found that its ligand PAF evoked EGFR phosphorylation. To determine whether PAFR targeting can enhance the antitumor efficacy of EGFR inhibition, we investigated the effects of a PAFR antagonist (WEB2086) in conjunction with an EGFR inhibitor (AG1478).

Among the pro-inflammatory lipid mediators, platelet-activating factor (PAF) is a major primary and secondary messenger that binds to the PAF-receptor (PAFR). Epidermal growth factor (EGF) is a polypeptide growth factor that binds to the EGF-receptor (EGFR). Evidence suggests that both PAF and EGF play a significant role in oncogenic transformation, tumor growth, neoangiogenesis and metastasis, including ovarian cancer. PAF has the potential to transactivate EGFR in ovarian cancer cells. This study explores the mechanisms involved in EGF-induced PAF production.

Objective: The aim of the study was to analyze the clinicopathologic features, the survival rate, and the prognostic factors of women with unexpected primary fallopian tube carcinoma diagnosed during gynecological operations. Materials and methods We reviewed medical records of patients with unexpected primary fallopian tube carcinoma at the Obstetrics and Gynecology Hospital of Fudan University between January 2004 to December 2017. The survival analysis was based on the Kaplan–Meier method, and the results were compared using the log-rank test. Cox regression analysis was used to determine factors affecting survival. Results: Sixty-seven patients with unexpected primary fallopian tube carcinoma were identified. The 5-year overall survival was 49.7%, the mean overall survival was 64 months [95% confidence interval (CI) 54–74], and the median overall survival was 59 months (95% CI 49–69). The mean follow-up time was 53.9 months (range 5–141 months). The most common clinical presentation was adnexal mass (38.8%), followed by vaginal bleeding (16.4%) and no specific symptom (13.4%). Cytoreductive surgery was performed initially in 57 (85.1%) patients. Residual disease was optimal in 56 (83.6%) patients and suboptimal in 11 (16.4%) patients. The histological subtype was predominantly the serous type (88.1%). 44 patients (65.7%) were diagnosed at Stage I/II postoperatively. 23 (34.3%) patients were in Stage III/IV. 51 patients (76.1%) had gone through laparoscopic surgery, 16 patients (23.9%) were performed laparotomy. Univariate analyses on overall survival revealed that only the International Federation of Gynecology and Obstetrics (FIGO)stage [p < 0.001; Hazard Ratio (HR), 6.433; 95% CI, 2.274–18.199], residual tumor (p = 0.014; HR, 4.957; 95% CI, 1.378–17.831) were significant prognostic factor. Pelvic lymphadenectomy did not show association with overall survival in our univariate or multivariate analyses. After an observation period of 70 months, we found an increased overall survival in the group of without lymphadenectomy. Conclusions: The diagnosis of primary fallopian tube carcinoma is rarely considered preoperatively. The early stage and optimal debulking surgery with residual tumor ≤1 cm are important independent factors to improve patients' prognosis. However, there were no statistically significant correlations between lymphadenectomy and prognosis. The value of lymph node sampling or dissection needs to be reconsidered.