Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy with high recurrence and poor prognosis duo to the lack of effective biomarkers. TBC1 domain family member 16 (TBC1D16), a GTPase-activating protein, is involved in regulating intracellular trafficking in tumorigenesis and metastasis. However, the clinical significance of TBC1D16 in EOC remains unknown. In the present study, we investigated the expression and prognostic significance of TBC1D16 in EOC and its relationship with the expression of vascular endothelial growth factor (VEGF). The tissue specimens included 156 histologically confirmed EOC and 30 normal ovarian tissues. The expression of TBC1D16 and VEGF was detected by immunohistochemistry (IHC), and the immunoreactive score was calculated with signal intensity and percentage of positive cells. IHC results showed that TBC1D16 and VEGF were both mainly localized in cytoplasm of epithelial cells in normal ovarian tissues and were expressed in cancer cells. Based on the immunoreactive score, TBC1D16 expression in EOC was categorized as "high expression," compared with normal ovarian tissues (P < 0.05). The Chi-square test showed that high TBC1D16 expression was related to advanced pT stages (P = 0.029), but not correlated with other clinical features. Moreover, the TBC1D16 expression was significantly higher in EOC specimens with low VEGF expression (P < 0.001). Importantly, in both univariate and multivariate survival analyses, high expression of TBC1D16 was significantly correlated with good overall survival (OS). In conclusion, TBC1D16 is a predictive marker for favorable prognosis of EOC.

Although ovarian cancer, a gynecological malignancy, has the highest fatality rate, it still lacks highly specific biomarkers, and the differential diagnosis of ovarian masses remains difficult to determine for gynecologists. Our study aimed to obtain ovarian cancer-specific protein candidates from the circulating small extracellular vesicles (sEVs) and develop a protein panel for ovarian cancer screening and differential diagnosis of ovarian masses. In our study, sEVs derived from the serum of healthy controls and patients with cystadenoma and ovarian cancer were investigated to obtain a cancer-specific proteomic profile. In a discovery cohort, 1119 proteins were identified, and significant differences in the protein profiles of EVs were observed among groups. Then, 23 differentially expressed proteins were assessed using the parallel reaction monitoring in a validation cohort. Through univariate and multivariate logistic regression analyses, a novel model comprising three proteins (fibrinogen gamma gene (FGG), mucin 16 (MUC16), and apolipoprotein (APOA4)) was established to screen patients with ovarian cancer. This model exhibited an area under the receiver operating characteristic curve (AUC) of 0.936 (95% CI, 0.888–0.984) with 92.0% sensitivity and 82.9% specificity. Another panel comprising serum CA125, sEV-APOA4, and sEV-CD5L showed excellent performance (AUC 0.945 (95% CI, 0.890–1.000), sensitivity of 88.0%, specificity of 93.3%, and accuracy of 89.2%) to distinguish malignancy from benign ovarian masses. Altogether, our study provided a proteomic signature of circulating sEVs in ovarian cancer. The diagnostic proteomic panel may complement current clinical diagnostic measures for screening ovarian cancer in the general population and the differential diagnosis of ovarian masses.

Background Increasing evidence has indicated that Maelstrom (MAEL) plays an oncogenic role in various human carcinomas. However, the exact function and mechanisms by which MAEL acts in epithelial ovarian cancer (EOC) remain unclear. Results This study demonstrated that MAEL was frequently overexpressed in EOC tissues and cell lines. Overexpression of MAEL was positively correlated with the histological grade of tumors, FIGO stage, and pT/pN/pM status (p < 0.05), and it also acted as an independent predictor of poor patient survival (p < 0.001). Ectopic overexpression of MAEL substantially promoted invasiveness/metastasis and induced epithelial-mesenchymal transition (EMT), whereas silencing MAEL by short hairpin RNA effectively inhibited its oncogenic function and attenuated EMT. Further study demonstrated that fibroblast growth factor receptor 4 (FGFR4) was a critical downstream target of MAEL in EOC, and the expression levels of FGFR4 were significantly associated with MAEL. (P < 0.05). Conclusion Our findings suggest that overexpression of MAEL plays a crucial oncogenic role in the development and progression of EOC through the upregulation of FGFR4 and subsequent induction of EMT, and also provide new insights on its potential as a therapeutic target for EOC.