Cisplatin-resistant Human Ovarian Cancer Cells Research Articles

Mechanism of Ellagic Acid-Induced Autophagy in Cis-Diamminedichloroplatinum(II)-Resistant Ovarian Cancer Cells

This study investigated the effect of ellagic acid on autophagy in cisplatin-resistant human epithelial ovarian cancer cells. After the autophagy double-labeled mred fluorescence protein, green fluorescence protein, light chain 3 carrying adenovirus infected cisplatin-resistant human epithelial ovarian cancer cells, the changes of autophagy flux and autophagy-related proteins were detected. Cell counting kit-8 assay was employed to detect the viability of cisplatin-resistant human epithelial ovarian cancer cells. The results showed that the number of autophagosomes and autolysosomes in the ellagic acid group increased significantly in comparison with the in cisplatin-resistant human epithelial ovarian cancer group. With the increase in ellagic acid concentration, light chain 3-II/I ratio and Beclin1 expression increased, p62 expression and cell viability decreased, and caspase-3 activated, in cisplatin-resistant human epithelial ovarian cancer cells. Conversely, 3-methyladenine inhibited ellagic acid-induced autophagy and activated caspase-3 and enhanced the cell viability. Similarly, chloroquine significantly increased cell survival rate, light chain 3-II/I ratio, and activated caspase-3, but decreased p62 expression in the ellagic acid group. In conclusion, ellagic acid can induce autophagy to inhibit the proliferation of cisplatin-resistant human epithelial ovarian cancer cells.

Fibroblast growth factor 21 is related to cisplatin resistance in ovarian cancer.

Fibroblast growth factor 21 is related to cisplatin resistance in ovarian cancer.

PI3K Inhibition Sensitize the Cisplatin-resistant Human Ovarian Cancer Cell OVCAR3 by Induction of Oxidative Stress.

This study evaluates the effect of simultaneous AKT inhibition and cisplatin therapy in changes of Reactive Oxygen Species (ROS) production, apoptosis induction, and cell survival in cisplatin-resistant OVCAR3 cell. OVCAR3 cancer cells were treated with cisplatin, Ly 294002 (LY), and cisplatin+Ly to investigate the cytotoxicity effect of the mentioned groups via MTT assay. Then, DCFH-DA (2', 7'-dichlorodihydro fluorescein diacetate) assay kit is used to assess the potential of treated groups in intracellular ROS generation. Protein expression levels of caspase-3, cleaved caspase 3, PI3K, Akt, p-Akt, XIAP, and Survivin are estimated through immunoblotting assay in all three experimental groups. The results showed that all three treated groups, including cisplatin and Ly alone and co-administration of cisplatin+Ly, could reduce the cell vitality of OVCAR3 cancer cells, induced intracellular production of ROS and increased the expression level of activated caspase 3 and Akt protein, whereas down-regulated the phosphorylation of Akt protein. However, the effect of combination therapy was more tangible compared to single therapy and control groups. In contrast, the expression amount of XIAP, Survivin, and PI3K did not show detectable changes in comparison with the control group. The results showed that the AKT inhibition by Ly could sensitize the OVCAR3 cancer cells to the cisplatin and lower the effective dose of cisplatin through hyperactivation of oxidative stress.

Distinct Side Population Cell Subtypes Have Different Stemness Levels in Human Ovarian Cancer Cells.

The stemness of different side population (SP) cell subtypes in ovarian cancer cells was studied, and the heterogeneity of ovarian cancer stem cells was analyzed. The cisplatin-resistant human serous ovarian cancer cell line C13 was stained with the bisbenzimide Hoechst 33342. A flow cytometry-based fluorescence-activated sorting method was used to obtain lower-SP (LSP) cells, upper-SP (USP) cells, and non-SP cells (NSP) based on their sensitivity to the staining time and Hoechst dye concentration. The sphere-forming capability, expression levels of stem cell markers, resistance to high concentrations of cisplatin, and subcutaneous tumorigenicity in NOD/SCID mice of the different cell subtypes were evaluated. The C13 cells contained SP cells with stemness characteristics, and the LSP cell subtype expressed higher levels of stem cell markers, had higher in vitro sphere-forming capability, higher cisplatin resistance and higher in vivo subcutaneous tumorigenesis than USP cells (P<0.05). NSP cells had no stemness. In conclusion, different subtypes of ovarian cancer SP cells have different stemness levels, and ovarian cancer stem cells may be heterogeneous.

Anticancer Activity Assessment and DNA Binding Properties of Two Binuclear Platinum (II) Complexes using Spectroscopic and Molecular Simulation Approaches.

Nowadays, the biological properties and anticancer activities of platinum-based drugs and metal coordination complexes have been receiving particular attention. These compounds have revealed clinical potential in cancer chemotherapy. In this research, two binuclear platinum complexes including [Pt2Cl2(bhq)2(μ-dppm)] (1) and [(p- MeC6H4)(bhq) Pt(μ-dppm)Pt(bhq)(CF3CO2)] (2) with bhq: benzo[h] quinolone and dppm: bis(diphenylphosphino) methane have been synthesized and evaluated for their anticancer activity against A2780 and A2780/RCIS cancer cell lines. The DNA binding and interaction of AMP/GMP nucleotide with these complexes were explored by several experimental and theoretical methods, including UV-Visible, fluorescence spectroscopic techniques and docking analysis. These complexes have demonstrated significant anticancer properties against cisplatinsensitive (A2780) and cisplatin-resistant (A2780/RCIS) human ovarian cancer cell lines. The obtained results indicated that these complexes interact with DNA. Additionally, the fluorescence emission measurements indicated that the platinum complexes binding with DNA structure occurs through nonintercalative interaction. The molecular docking assessments have also revealed the binding of these platinum complexes through DNA grooves. Moreover, the results have indicated that complex 1 exhibited more anticancer activity than complex 2. The results of the DNA binding with these platinum complexes confirmed their potential antitumor properties. The substitution of -C6H4CH3 and -CO2CF3 groups in complex 2 with two chlorine atoms in complex 1 acquired the significant improvement of the anticancer activity against the cancer cell.

Cytotoxicity of some synthetic bis(arylidene) derivatives of cyclic ketones towards cisplatin-resistant human ovarian carcinoma cells

Symmetrical α,αʹ-bis(arylidene)ketones were prepared by acid-catalyzed aldol condensations between aliphatic ketones (e.g., cyclopentanone, 4-alkylcyclohexanones, tetrahydropyran-4-one, and tetrahydrothiopyran-4-one) and two equivalents of an aromatic hydroxyaldehyde (e.g., 4-hydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, vanillin, isovanillin, and 3-fluoro-4-hydroxybenzaldehyde). Most of the compounds were cytotoxic towards the cisplatin-resistant human ovarian cancer cell line A2780-CP70 as well as the non-resistant line A2780.

Impact of the histone deacetylase inhibitor trichostatin A on active uptake, volume-sensitive release of taurine, and cell fate in human ovarian cancer cells.

The histone deacetylase inhibitor trichostatin A (TSA) reduces cell viability in cisplatin-sensitive (A2780WT) and cisplatin-resistant (A2780RES) human ovarian cancer cells due to progression of apoptosis (increased caspase-9 activity), autophagy (increased LC3-II expression), and cell cycle arrest (increased p21 expression). The TSA-mediated effect on p21 and caspase-9 is mainly p53 independent. Cisplatin increases DNA-damage (histone H2AX phosphorylation) in A2780WT cells, whereas cisplatin, due to reduced uptake [inductively coupled-plasma-mass spectrometry (Pt) analysis], has no DNA-damaging effect in A2780RES cells. TSA has no effect on cisplatin accumulation or cisplatin-induced DNA-damage in A2780WT/A2780RES cells. Tracer technique indicates that TSA inhibits the volume-sensitive organic anion channel (VSOAC) in A2780WT/A2780RES cells and that the activity is restored by exogenous H2O2. As TSA reduces NOX4 mRNA accumulation and concomitantly increases catalase mRNA/protein accumulation, we suggest that TSA increases the antioxidative defense in A2780 cells. Inhibition of the kinase mTOR (rapamycin, palomid, siRNA), which is normally associated with cell growth, reduces VSOAC activity synergistically to TSA. However, as TSA increases mTOR activity (phosphorylation of 4EBP1, S6 kinase, S6, ULK1, SGK1), the effect of TSA on VSOAC activity does not reflect the shift in mTOR signaling. Upregulation of the protein expression and activity of the taurine transporter (TauT) is a phenotypic characteristic of A2780RES cells. However, TSA reduces TauT protein expression in A2780RES cells and activity to values seen in A2780WT cells. It is suggested that therapeutic benefits of TSA in A2780 do not imply facilitation of cisplatin uptake but more likely a synergistic activation of apoptosis/autophagy and reduced TauT activity.

Valspodar-modulated chemotherapy in human ovarian cancer cells SK-OV-3 and MDAH-2774.

Overcoming drug resistance in ovarian cancer is the overarching goal in gynecologic oncology. One way to increase drug cytotoxicity without increasing the drug dose is to simultaneously apply multidrug resistance modulator. Valspodar is the second generation P-glycoprotein 1 modulator capable of reversing multidrug resistance in different cancers. In this study, we evaluated the effect of valspodar and cisplatin co-treatment on cell viability, cell death and oxidative status in ovarian cancer cells. Two human ovarian cancer cell lines SK-OV-3 and MDAH-2774 were treated with cisplatin, valspodar, or cisplatin + valspodar for 24 or 48 hours. Untreated cells were used as control group. Cell viability was evaluated by MTT assay. Cell death was assessed by TUNEL and comet assay. Lipid peroxidation (malondialdehyde) and protein thiol groups were analyzed as oxidative stress markers. The expression of mitochondrial superoxide dismutase (MnSOD) was assessed by immunocytochemistry. Valspodar effectively reduced the resistance of SK-OV-3 cells to cisplatin, as demonstrated by increased oxidative stress, decreased cell viability and increased apoptosis in SK-OV-3 cells co-treated with valspodar and cisplatin compared to other groups. However, valspodar did not significantly affect the resistance of MDAH-2774 cells to cisplatin. Stronger staining for MnSOD in MDAH-2774 vs. SK-OV-3 cells after co-treatment with cisplatin and valspodar may determine the resistance of MDAH-2774 cell line to cisplatin.

Small-molecule compounds targeting the STAT3 DNA-binding domain suppress survival of cisplatin-resistant human ovarian cancer cells by inducing apoptosis

Constitutive activation of signal transducer and activator of transcription 3 (STAT3) plays important roles in oncogenic occurrence and transformation by regulating the expression of diverse downstream target genes important for tumor growth, metastasis, angiogenesis and immune evasion. Feasibility of targeting the DNA-binding domain (DBD) of STAT3 has been proven previously. With the aid of 3D shape- and electrostatic-based drug design, we identified a new STAT3 inhibitor, LC28, and its five analogs, based on the pharmacophore of a known STAT3 DBD inhibitor. Microscale thermophoresis assay shows that these compounds inhibits STAT3 binding to DNA with a Ki value of 0.74–8.87 μM. Furthermore, LC28 and its analogs suppress survival of cisplatin-resistant ovarian cancer cells by inhibiting STAT3 signaling and inducing apoptosis. Therefore, these compounds may serve as candidate compounds for further modification and development as anticancer therapeutics targeting the DBD of human STAT3 for treatment of cisplatin-resistant ovarian cancer.

Nanosecond Electric Pulses Induce Early and Late Phases of DNA Damage and Cell Death in Cisplatin-Resistant Human Ovarian Cancer Cells.

Chemoresistance is a challenge for management of ovarian cancer, and therefore the response of resistant cells to nanosecond electric pulses (nsEP) was explored. Human ovarian cancer cell line COC1 and the cisplatin-resistant subline COC1/DDP were subjected to nsEP (32 ns, 10 kV/cm, 10 Hz pulse repletion frequency, and 10 min exposure duration), and then the cellular responses were followed. The percentages of dead cells and of comet-formed cells in the alkaline assay displayed two peak levels (i.e., 2 and 8 h after nsEP exposure), with the highest value noted at 8 h; the percentage of comet-formed cells in the neutral assay was increased at 8 h; the apoptotic percentage was increased at 8 h, with collapse of the mitochondrial membrane potential and the activation of caspase-3 and caspase-9. The comet assay demonstrated DNA single-strand break at 2 h and double-strand break at 8 h. nsEP resulted in lower cytotoxicity in COC1/DDP cells compared with COC1 cells. These findings indicated that nsEP induced early and late phases of DNA damage and cell death, and these two types of cell death may have distinct applications to treatments of chemoresistant ovarian cancers.

ABCF2, an Nrf2 target gene, contributes to cisplatin resistance in ovarian cancer cells.

Previously, we have demonstrated that NRF2 plays a key role in mediating cisplatin resistance in ovarian cancer. To further explore the mechanism underlying NRF2-dependent cisplatin resistance, we stably overexpressed or knocked down NRF2 in parental and cisplatin-resistant human ovarian cancer cells, respectively. These two pairs of stable cell lines were then subjected to microarray analysis, where we identified 18 putative NRF2 target genes. Among these genes, ABCF2, a cytosolic member of the ABC superfamily of transporters, has previously been reported to contribute to chemoresistance in clear cell ovarian cancer. A detailed analysis on ABCF2 revealed a functional antioxidant response element (ARE) in its promoter region, establishing ABCF2 as an NRF2 target gene. Next, we investigated the contribution of ABCF2 in NRF2-mediated cisplatin resistance using our stable ovarian cancer cell lines. The NRF2-overexpressing cell line, containing high levels of ABCF2, was more resistant to cisplatin-induced apoptosis compared to its control cell line; whereas the NRF2 knockdown cell line with low levels of ABCF2, was more sensitive to cisplatin treatment than its control cell line. Furthermore, transient overexpression of ABCF2 in the parental cells decreased apoptosis and increased cell viability following cisplatin treatment. Conversely, knockdown of ABCF2 using specific siRNA notably increased apoptosis and decreased cell viability in cisplatin-resistant cells treated with cisplatin. This data indicate that the novel NRF2 target gene, ABCF2, plays a critical role in cisplatin resistance in ovarian cancer, and that targeting ABCF2 may be a new strategy to improve chemotherapeutic efficiency.

The cytoplasmic translocation of Cx32 mediates cisplatin resistance in ovarian cancer cells

Ovarian cancer is the most lethal gynecologic malignancy, and cisplatin is one of the first-line chemotherapeutic agents. However, acquired cisplatin resistance prevents the successful treatment of patients with ovarian cancer. Gap junction (GJ) and connexin (Cx) are closely related to tumor formation, but the relationship between cisplatin resistance and GJ or Cx are undetermined. In this study, we established the cisplatin-resistant human ovarian cancer cell line A2780-CDDP. Here we showed that cisplatin resistance was correlated to the loss of GJ and the upregulation of Cx32 expression. Enhancing GJ in A2780-CDDP cells could increase the apoptotic response to cisplatin treatment. Furthermore, although Cx32 expression was increased in A2780-CDDP cells, it was more localized to the cytoplasm rather than in the membrane, and knockdown of Cx32 in A2780-CDDP cells sensitized them to cisplatin treatment. In summary, Cx32 is involved in cisplatin resistance, and cytoplasmic Cx32 plays an important role in chemoresistance.

Bis-picolinamide Ruthenium(III) Dihalide Complexes: Dichloride-to-Diiodide Exchange Generates Single trans Isomers with High Potency and Cancer Cell Selectivity.

A library of new bis-picolinamide ruthenium(III) dihalide complexes of the type [RuX2 L2 ] (X=Cl or I, L=picolinamide) have been synthesised and characterised. The complexes exhibit different picolinamide ligand binding modes, whereby one ligand is bound (N,N) and the other bound (N,O). Structural studies revealed a mixture of cis and trans isomers for the [RuCl2 L2 ] complexes but upon a halide exchange reaction to yield [RuI2 L2 ], only single trans isomers were detected. High cytotoxic activity against human cancer cell lines was observed, with the potencies of some complexes similar to or better than cisplatin. The conversion to [RuI2 L2 ] substantially increased the activity towards cancer cell lines by more than twelvefold. The [RuI2 L2 ] complexes displayed potent activity against the A2780cis (cisplatin-resistant human ovarian cancer) cell line, with a more than fourfold higher potency than cisplatin. Equitoxic activity was observed against normoxic and hypoxic cancer cells, which indicates the potential to eradicate both the hypoxic and aerobic fractions of solid tumours with similar efficiency. The activity of selected complexes against non-cancer ARPE-19 cells was also tested. The [RuI2 L2 ] complexes were found to be more potent than the [RuCl2 L2 ] analogues and also more selective towards cancer cells with a selectivity factor in excess of sevenfold.

Three Diketopiperazine Alkaloids with Spirocyclic Skeletons and One Bisthiodiketopiperazine Derivative from the Mangrove-Derived Endophytic Fungus Penicillium brocae MA-231.

Four new diketopiperazines including spirobrocazines A-C (1-3) and brocazine G (4) were characterized from the mangrove-derived Penicillium brocae MA-231. Compounds 1 and 2 had a 6/5/6/5/6 cyclic system with a rare spirocyclic center at C-2. Their structures and absolute configurations were determined by spectroscopic analysis, TDDFT-ECD calculations, and X-ray diffraction. Compound 4 exhibited potent cytotoxicity against both sensitive and cisplatin-resistant human ovarian cancer cells and strong antimicrobial activity against pathogenic Staphylococcus aureus.

Lysine-specific demethylase KDM3A regulates ovarian cancer stemness and chemoresistance

Ovarian cancer is the leading cause of death among all gynecological malignancies due to the development of acquired chemoresistance and disease relapse. Although the role of cancer stem cells (CSCs), a subset of tumor cells with the self-renewal and differentiation capabilities, in therapeutic resistance is beginning to be better understood, the significance of epigenetic regulatory mechanisms responsible for integrating the stemness with drug resistance remain poorly understood. Here we identified that lysine demethylase KDM3A as a critical regulator of ovarian cancer stemness and cisplatin resistance by inducing the expressions of pluripotent molecules Sox2 and Nanog and anti-apoptotic B-cell lymphoma 2 (Bcl-2), respectively. In addition, KDM3A induces ovarian cancer growth while antagonizing cellular senescence by repressing the expression of cyclin-dependent kinase inhibitor, p21Waf1/Cip1. The underlying mechanism of the noted biological processes include KDM3A-mediated stimulation of Sox2 expression, and demethylating p53 protein and consequently, modulating its target genes such as Bcl-2 and p21Waf1/Cip1 expression. Consistently, KDM3A depletion inhibited the growth of subcutaneously implanted cisplatin-resistant human ovarian cancer cells in athymic nude mice. Moreover, KDM3A is abundantly expressed and positively correlated with Sox2 expression in human ovarian cancer tissues. In brief, our findings reveal a novel mechanism by which KDM3A promotes ovarian CSCs, proliferation and chemoresistance and thus, highlights the significance of KDM3A as a novel therapeutic target for resistant ovarian cancer.

Abstract 2803: Distinct roles of intracellular ROS in cisplatin and evofosfamide cytotoxicity

Abstract Cisplatin is one of the most widely used anticancer agents for the treatment of an array of malignancies. Although multiple mechanisms are involved in cisplatin efficacy, the most prominent and best understood modes of action are the generation of DNA lesions and induction of apoptosis and mitochondrial reactive oxygen species (ROS)-dependent effects on mitochondrial integrity. However, intrinsic or acquired cisplatin resistance can become a limiting factor in cisplatin-based therapy. Evofosfamide is a hypoxia-activated prodrug that is reduced at its nitroimidazole group and preferentially under hypoxic conditions releases Br-IPM, a DNA cross-linker. Evofosfamide is currently being investigated in multiple clinical trials for the treatment of cancer including indications and settings where resistance to cisplatin is observed (e.g. second-line non-small cell lung cancer; NCT01403610). We have previously demonstrated both shared and distinct DNA repair pathways involved with evofosfamide and cisplatin DNA damage. In the current study, we have conducted comparative studies to identify any distinctions in the relative role of ROS underlying cell sensitivity to cisplatin and evofosfamide to help evaluate the potential of evofosfamide to treat cisplatin-resistant tumors. The cisplatin-sensitive cervical cancer cell line ME180, the intermediate cisplatin-resistant human ovarian cancer cell line SK-OV-3, and cisplatin-resistant human lung cancer cell line A549 were investigated with respect to their chemosensitivity to evofosfamide. Unlike cisplatin, evofosfamide exhibited similar potency across all three cell lines. Addition of the ROS scavenger N-acetyl-L-cysteine (NAC) reduced the potency of cisplatin- but not evofosfamide-mediated cytotoxicity, indicating ROS plays a role in cytotoxicity mediated by cisplatin, but not evofosfamide. ROS levels were investigated using the dye H2DCFDA. Cisplatin induced a concentration-dependent and NAC-inhibitable increase of cellular ROS in cisplatin-sensitive ME-180 cells but not in cisplatin-resistant A549 cells. In contrast, ROS levels were not affected by the addition of evofosfamide under normoxia and hypoxia in both ME180 and A549 cells. In order to ascertain whether mitochondrial pathway-mediated apoptosis was involved in cytotoxicity mediated by evofosfamide and cisplatin, mitochondrial membrane depolarization was investigated with the dye JC-1. Cisplatin induced a concentration-dependent JC-1 polarization and these effects were abolished by NAC. In contrast, evofosfamide did not affect mitochondrial membrane potential. In conclusion, this data demonstrates that ROS is an essential factor in cisplatin-mediated cytotoxicity, but not in evofosfamide-mediated cytotoxicity. Citation Format: Fanying Meng, Deepthi Bhupathi, Geraldine Chan, Charles P. Hart. Distinct roles of intracellular ROS in cisplatin and evofosfamide cytotoxicity. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2803.

YAP induces cisplatin resistance through activation of autophagy in human ovarian carcinoma cells.

ObjectiveTo identify the role of YAP in cisplatin resistance in human ovarian cancer cells and in the regulation of autophagy in these cancer cells.Materials and methodsThe cisplatin-sensitive OV2008 parental cell line and its cisplatin-resistant variant C13K were cultured. RNA interference was used to knock down the YAP gene. Accumulation of GFP-LC3 puncta was performed by fluorescence microscopy. The formation of autophagosomes was observed by transmission electron microscopy. Drug sensitivity was examined using CCK-8 assay, while apoptosis, the level of intracellular rhodamine 123 and lysosomal acidification were analyzed by fluorescence-activated cell sorting. Acid phosphatase activity was measured using an acid phosphatase-assay kit. Real-time polymerase chain reaction, Western blotting, and immunofluorescence detection were used to detect the protein and messenger RNA expression of YAP, YAP target genes, CCND1, cleaved PARP, and caspase 3, Atg-3 and -5, and the LC3B protein.ResultsYAP signaling may regulate cisplatin resistance in ovarian cancer cells by augmenting cellular autophagic flux. After knockdown of YAP-sensitized C13K cells to cisplatin by inducing a decrease in autophagy, YAP led to an increase in autophagy via enhancement of autolysosome degradation.ConclusionYAP-mediated autophagy may play a protective role in cisplatin-resistant human ovarian cancer cells. Therefore, YAP-mediated autophagy should be explored as a new target for enhancing the efficacy of cisplatin against ovarian cancer and other types of malignancies.

Knockdown of MACC1 expression increases cisplatin sensitivity in cisplatin-resistant epithelial ovarian cancer cells.

Abnormal expression of metastasis-associated in colon cancer 1 (MACC1) was found to be closely associated with several types of malignant tumors. The present study aimed to verify the relationship between MACC1 and cisplatin resistance in ovarian cancer cells and the possible mechanisms, which was implemented by inhibition of the expression of MACC1 in cisplatin-resistant human ovarian cancer cell lines A2780/DDP and COC1/DDP. MACC1 shRNA eukaryotic plasmids and negative control plasmids were transfected into A2780/DDP and COC1/DDP cells, respectively, while A2780/DDP and COC1/DDP cells were used as blank controls. Western blotting and sqRT-PCR were used to detect the expression of MACC1 in the different cell groups. Different concentrations of cispaltin (0, 10, 20, 30, 40, 50 and 60 µmol/l) were used to treat the cell groups, respectively, and then the chemosensitivity of cisplatin and cell apoptosis were examined by MTT and flow cytometry, respectively. The activity of caspase-3 was determined by spectrophotometry. Expression levels of p-ERK1/2, permeability glycoprotein (P-gp), B-cell lymphoma 2 (Bcl-2), Bcl-XL, Bax and Bad protein were detected in the different ovarian cancer cells by western blotting. After MACC1 knockdown, the chemosensitivity of cisplatin in the ovarian cancer cells was enhanced, and the cell growth inhibition and apoptosis rates were increased. The expression levels of Bax and Bad were upregulated, the activity of caspase-3 was increased, while the expression levels of p-ERK1/2, P-gp, Bcl-2 and Bcl-XL were downregulated as a result of MACC1 inhibition. These results indicate that inhibition of MACC1 improves the chemosensitivity of cisplatin in epithelial ovarian cancer cells, through the regulation of the ERK1/2 signaling pathway on P-gp and its downstream apoptosis proteins.

Guizhi Fuling Wan, a Traditional Chinese Herbal Formula, Sensitizes Cisplatin-Resistant Human Ovarian Cancer Cells through Inactivation of the PI3K/AKT/mTOR Pathway.

The aim of the study was to explore the possible mechanisms that Guizhi Fuling Wan (GFW) enhances the sensitivity of the SKOV3/DDP ovarian cancer cells and the resistant xenograft tumours to cisplatin. Rat medicated sera containing GFW were prepared by administering GFW to rats, and the primary bioactive constituents of the sera were gallic acid, paeonol, and paeoniflorin analysed by HPLC/QqQ MS. Cell counting kit-8 analysis was shown that coincubation of the sera with cisplatin/paclitaxel enhanced significantly the cytotoxic effect of cisplatin or paclitaxel in SKOV3/DDP cells. The presence of the rat medicated sera containing GFW resulted in an increase in rhodamine 123 accumulation by flow cytometric assays and a decrease in the protein levels of P-gp, phosphorylation of AKT at Ser473, and mTOR in a dose-dependent manner in SKOV3/DDP cells by western blot analysis, but the sera had no effect on the protein levels of PI3K p110α and total AKT. The low dose of GFW enhanced the anticancer efficacy of cisplatin and paclitaxel treatment in resistant SKOV3/DDP xenograft tumours. GFW could sensitize cisplatin-resistant SKOV3/DDP cells by inhibiting the protein level and function of P-gp, which may be medicated through inactivation of the PI3K/AKT/mTOR pathway.

A Pt(IV) Pro-drug Preferentially Targets Indoleamine-2,3-dioxygenase, Providing Enhanced Ovarian Cancer Immuno-Chemotherapy.

Expression of indoleamine-2,3-dioxygenase (IDO), an immunosuppressive enzyme in human tumors, leads to immune evasion and tumor tolerance. IDO is therefore a tumor immunotherapeutic target, and several IDO inhibitors are currently undergoing clinical trials. IDO inhibitors can enhance the efficacy of common cancer chemotherapeutics. Here we investigate Pt(IV)-(D)-1-methyltryptophan conjugates 1 and 2 for combined immunomodulation and DNA cross-link-triggered apoptosis for cancer "immuno-chemotherapy". Compound 2 effectively kills hormone-dependent, cisplatin-resistant human ovarian cancer cells, inhibiting IDO by transcriptional deregulation of the autocrine-signaling loop IDO-AHR-IL6, which blocks kynurenine production and promotes T-cell proliferation. Additionally, 1 and 2 display low toxicity in mice and are stable in blood. To our knowledge, this construct is the first Pt drug candidate with immune checkpoint blockade properties.