Folia Biologica

Dysregulated BARD1 Contributes to Paclitaxel Resistance in Ovarian Cancer via Up-regulating CYP2C8

Ovarian cancer remains one of the most lethal gynaecological malignancies, with paclitaxel resistance being a major therapeutic challenge that limits treatment efficacy and patient survival. We found that although the BARD1 level was not signi­ficantly altered in patients with ovarian cancer (OC), patients with higher BARD1 levels had increased survival time, suggesting that the down-regulation of BARD1 may be related to the paclitaxel sensitivity. Through examining the expression of BARD1 in tumour samples from paclitaxel responders and non-responders, we observed that the BARD1 level was significantly reduced in non-responders. CYP2C8 was up-regulated in non-responders. Also, the BARD1 level was negatively correlated with the level of CYP2C8. BARD1 over-expression in OC cells could repress the CYP2C8 expression, while knockdown of BARD1 could up-regulate CYP2C8 expression, which could be rescued by H2A-Ub. Results from gain and loss of functional experiments indicated that BARD1 functions as a tumour suppressor during paclitaxel treatment, and BARD1 down-regulation increased the IC50 of paclitaxel from 2.46 nM to 5.33 nM in SK-OV-3 cells and from 3.11 nM to 7.51 nM in CaoV-3 cells. We are the first to demonstrate that the down-regulation of BARD1 contributes to paclitaxel resistance via up-regulating CYP2C8 in patients with OC, which provides a potent target for clinical OC treatment.

MiR-19a-3p Promotes Aerobic Glycolysis in Ovarian Cancer Cells via IGFBP3/PI3K/AKT Pathway

Aerobic glycolysis is a prominent feature of cancer. Here, we reported that miR-19a-3p promotes aerobic glycolysis in ovarian cancer cells SKVO3 and ES-2 by increased production of ATP, lactic acid, extracellular acidification (ECAR), and increased expression of PKM2, LDHA, GLUT1 and GLUT3. Further study showed that over-expression of IGFBP3, the target of miR-19a-3p, decreases aerobic glycolysis in ovarian cancer cells, while knockdown of IGFBP3 expression increases aerobic glycolysis. The rescue assay suggested that miR-19a-3p promotes aerobic glycolysis in ovarian cancer cells through targeting IGFBP3. Moreover, over-expression of miR-19a-3p or silencing of IGFBP3 expression promoted activation of AKT, which is important for aerobic glycolysis in cancer cells, indicating that miR-19a-3p promotes aerobic glycolysis in ovarian cancer cells through the IGFBP3/PI3K/AKT pathway. This suggests that miR-19a-3p and IGFBP3 may serve as potential treatment targets of ovarian cancer.

Down-regulation of lncRNA EMX2OS Is Associated with the Prognosis of Patients with Cervical Squamous Cell Carcinoma and Regulates Tumour Cell Progression via miR-574-5p

Cervical squamous cell carcinoma (CSCC) represents a malignant subtype of cervical cancer. Identification of novel biomarkers for CSCC development could enhance therapeutic efficiency and improve the patients’ outcomes. This study focused on lncRNA EMX2OS, evaluating its expression and significance in the progression of CSCC while exploring its potential as a therapeutic target. A cohort of 135 patients with CSCC were enrolled, and tissue samples were collected for analysis. The expression of EMX2OS in the tissues was quantified by PCR, with its correlation to the clinicopathological features, and prognosis was evaluated by χ 2 , Kaplan-Meier and Cox regression analyses. The regulatory effects of EMX2OS on CSCC cells were investigated by CCK8 and Transwell assays, while the underlying molecular mechanisms were elucidated by luciferase reporter assays. Significant down-regulation of EMX2OS was observed in CSCC, correlating with advanced FIGO stages, poor differentiation and adverse prognosis of patients. Over-expression of EMX2OS significantly suppressed cell growth and metastasis in CSCC. Negative regulation of miR-574-5p by EMX2OS was observed, and over-expression of miR-574-5p alleviated the inhibition of CSCC cells by EMX2OS. Down-regulated EMX2OS indicates severe disease progression and poor prognosis in CSCC. Over-expression of EMX2OS could inhibit CSCC cell growth and metastasis by negatively modulating miR-574-5p.

Kaempferol Induces Cell Death in A2780 Ovarian Cancer Cells and Increases Their Sensitivity to Cisplatin by Activation of Cytotoxic Endoplasmic Reticulum-Mediated Autophagy and Inhibition of Protein Kinase B

This study investigated whether kaempferol could inhibit ovarian cancer (OC) by activation of endoplasmic reticulum (ER) stress and autophagy, and tested its effect on the sensitivity of OC cells to cisplatin (cis-diamminedichloroplatinum, DPP). To study the effect of kaempferol on activation of ER stress and autophagy and find out whether its mechanism of action involves calcium (Ca 2+ ), A2780 OC cells were cultured in DMEM/F12 for 24 h with or without kaempferol (40 μmol/l) in the presence or absence of autophagy or ER stress inhibitors or a calcium chelator. To study the effect of kaempferol on the sensitivity of OC cells to DPP and the potential involvement of modulation of protein kinase B (Akt) expression, A2780 OC were incubated with kaempferol and increasing concentrations of DPP (0–20 μmol/l) and then with kaempferol at its predetermined IC 50 (6.8 μmol/l). Compared to control cells, kaempferol increased cell apoptosis (158 %) and decreased viability (53.17 %) and proliferation (49.17 %) of A2780 OC cells. Concomitantly, it increased the protein levels of GRP78, PERK, ATF6, IRE-1, LC3II, beclin 1, and caspase 4, thus suggesting activation of cytotoxic autophagy. This was mediated by increasing intracellular Ca 2+ levels. In addition, kaempferol increased the sensitivity of A2780 cells to DPP (IC 50 from 6.867 ± 0.99 to 3.73 ± 0.59 μmol/l) by decreasing the protein levels of p-Akt (0.31 ± 0.09 vs 0.12 ± 0.005). In conclusion, the findings of this study encourage the use of kaempferol alone or in combination with DPP to inhibit tumorigenesis of ovarian cells.

Exendin-4 Induces Cytotoxic Autophagy in Two Ovarian Cancer Cell Lines through Inhibition of Mtorc1 Mediated by Activation of AMPK and Suppression of Akt

Activation of autophagy suppresses ovarian cancer (OC). This in vitro study investigated whether the anti-tumour effect of exendin-4 against OC involves modulation of autophagy and figured out the possible mechanisms of action. SKOV-3 and OVCAR-3 cells (1 × 10 5 /ml) were cultured in DMEM medium and treated with exendin-4 in the presence or absence of chloroquine (CQ), an autophagy inhibitor. In some cases, cells were also treated with exendin- 4 with or without pre-treatment with compound C (CC), an AMPK inhibitor, or insulin-like growth factor (IGF-1), a PI3K/Akt activator. Exendin-4 increased expression of beclin-1 and LC3I/II, suppressed expression of p62, reduced cell survival, migration, and invasion, and increased cell apoptosis and LDH release in both SKOV-3 and OVCAR-3 cells. Besides, exendin-4 reduced phosphorylation of mTORC1, 6SK, 4E-BP1, and Akt but increased phosphorylation of AMPK in both cell lines. These effects were associated with down-regulation of Bcl-2, suppression of nuclear phosphorylation of NF-κB p65, and increased expression of Bax and cleaved caspases 3/8. Chloroquine completely prevented the inhibitory effects of exendin-4 on the cell survival, Bcl-2, NF-κB, and cell invasiveness and abolished its stimulation of cell apoptosis and LDH release. Moreover, only the combined treatment with IGF-1 and CC completely abolished the observed effect of exendin-4 on the expression of beclin-1, LC3I/II, p62, as well as on cell survival, apoptosis, and LDH release. Exendin-4 exhibits a potent anti-tumour cytotoxic effect in SKOV-3 and OVCAR-3 cells by activating the markers of autophagy, mediated by activation of AMPK and inhibition of Akt.