Chemosensitivity In Ovarian Cancer Research Articles

Multiple Potential Markers of Chemosensitivity of Ovarian Cancer, Among Which KELIM of CA125 Is Low Cost and Efficient

Multiple Potential Markers of Chemosensitivity of Ovarian Cancer, Among Which KELIM of CA125 Is Low Cost and Efficient

Utilizing the KELIM score and the chemo-response score to predict chemosensitivity in ovarian cancer (1212)

Utilizing the KELIM score and the chemo-response score to predict chemosensitivity in ovarian cancer (1212)

Tripterygium glycosides reverse chemotherapy resistance in ovarian cancer by targeting the NRF2/GPX4 signal axis to induce ferroptosis of drug-resistant human epithelial ovarian cancer cells

Cisplatin resistance is the main cause of postoperative recurrence and difficulty in the treatment of ovarian cancer. It is urgently needed to identify therapeutic drugs with unique functions to overcome the current challenges in the treatment of ovarian cancer. In this study, we found that TG promoted the accumulation of ROS and MDA in A2780/DDP cells and downregulated the expression of key antioxidant molecules. In vivo, the survival rate of tumor-bearing nude mice was prolonged by TG without significant hepatotoxic reaction. The expression of key antioxidant molecules in tumor tissues was consistent with that in vitro. These findings revealed that TG disrupted homeostasis of redox reactions and induced ferroptosis in A2780/DDP cells, thereby enhancing cisplatin chemosensitivity of ovarian cancer. Overall, TG may be a novel potential therapeutic option for reversing resistance to cisplatin chemotherapy.

FOXD3 confers chemo-sensitivity in ovarian cancer through a miR-335/DAAM1/myosin II axis-dependent mechanism

BackgroundChemotherapy is among the most common treatment methods for ovarian cancer (OC). However, chemoresistance limits the effectiveness of chemotherapy and leads to treatment failure. We herein investigate the biological effect of forkhead box D3 (FOXD3) in the chemoresistance of OC cells.MethodsExpression of FOXD3, miR-335 and disheveled-associated activator of morphogenesis 1 (DAAM1) was detected in OC cells and tissues. The regulatory network of FOXD3/miR-335/DAAM1 was validated by dual-luciferase reporter and ChIP assays in vitro. After ectopic expression and depletion experiments in carboplatin/paclitaxel (CP)-resistant (A2780CP) or sensitive (A2780S) OC cells, cell viability, colony formation and apoptosis were tested by CCK-8 assay, colony formation assay and flow cytometry respectively. Effects of FOXD3 on the chemoresistance of OC cells in vivo were evaluated in OC xenografts in nude mice.ResultsOverexpression of FOXD3 impaired the proliferation and chemoresistance of OC cells, which was related to the promotion of the miR-335 expression. Functionally, DAAM1 was a putative target of miR-335. Silencing of DAAM1 was responsible for the inhibition of myosin II activation, consequently leading to suppressed OC cell proliferation and chemoresistance. In vivo results further showed that FOXD3 weakened the chemoresistance of OC cells to CP.ConclusionTaken together, we unveil a novel FOXD3/miR-335/DAAM1/myosin II axis that regulates the chemoresistance of OC both in vitro and in vivo.

Knock down of TIMP-2 by siRNA and CRISPR/Cas9 mediates diverse cellular reprogramming of metastasis and chemosensitivity in ovarian cancer

BackgroundThe endogenous tissue inhibitor of metalloproteinase-2 (TIMP-2), through its homeostatic action on certain metalloproteinases, plays a vital role in remodelling extracellular matrix (ECM) to facilitate cancer progression. This study investigated the role of TIMP-2 in an ovarian cancer cell line in which the expression of TIMP-2 was reduced by either siRNA or CRISPR/Cas9.MethodsOVCAR5 cells were transiently and stably transfected with either single or pooled TIMP-2 siRNAs (T2-KD cells) or by CRISPR/Cas9 under the influence of two distinct guide RNAs (gRNA1 and gRNA2 cell lines). The expression of different genes was analysed at the mRNA level by quantitative real time PCR (qRT-PCR) and at the protein level by immunofluorescence (IF) and western blot. Proliferation of cells was investigated by 5-Ethynyl-2′-deoxyuridine (EdU) assay or staining with Ki67. Cell migration/invasion was determined by xCELLigence. Cell growth in vitro was determined by 3D spheroid cultures and in vivo by a mouse xenograft model.ResultsApproximately 70–90% knock down of TIMP-2 expression were confirmed in T2-KD, gRNA1 and gRNA2 OVCAR5 ovarian cancer cells at the protein level. T2-KD, gRNA1 and gRNA2 cells exhibited a significant downregulation of MMP-2 expression, but concurrently a significant upregulation in the expression of membrane bound MMP-14 compared to control and parental cells. Enhanced proliferation and invasion were exhibited in all TIMP-2 knocked down cells but differences in sensitivity to paclitaxel (PTX) treatment were observed, with T2-KD cells and gRNA2 cell line being sensitive, while the gRNA1 cell line was resistant to PTX treatment. In addition, significant differences in the growth of gRNA1 and gRNA2 cell lines were observed in in vitro 3D cultures as well as in an in vivo mouse xenograft model.ConclusionsOur results suggest that the inhibition of TIMP-2 by siRNA and CRISPR/Cas-9 modulate the expression of MMP-2 and MMP-14 and reprogram ovarian cancer cells to facilitate proliferation and invasion. Distinct disparities in in vitro chemosensitivity and growth in 3D culture, and differences in tumour burden and invasion to proximal organs in a mouse model imply that selective suppression of TIMP-2 expression by siRNA or CRISPR/Cas-9 alters important aspects of metastasis and chemosensitivity in ovarian cancer.

Exploring Metabolic Signatures of Ex Vivo Tumor Tissue Cultures for Prediction of Chemosensitivity in Ovarian Cancer.

Simple SummaryWomen diagnosed with ovarian cancer have 5-year survival rates below 45%. Prediction of patient’s outcome and the onset of drug resistance are still major challenges. The patient’s drug response is influenced by the environment that surrounds the tumor cells. We previously showed that patient-derived tumor tissue can be kept in the lab, alive and retaining aspects of that environment. In this study, we exposed tumor tissue derived from ovarian cancer patients to the chemotherapy patients receive and identified metabolites released by the tumor tissue after treatment (metabolic footprint). Using machine learning, we uncovered metabolic signatures that discriminate tumor tissues with higher vs. lower drug sensitivity. We propose potential biomarkers involved in the production of specific building blocks of cells and energy generation processes. Overall, we established a platform to explore metabolic features of the complex environment of each patient’s tumor that can underpin the discovery of biomarkers of drug response.Predicting patient response to treatment and the onset of chemoresistance are still major challenges in oncology. Chemoresistance is deeply influenced by the complex cellular interactions occurring within the tumor microenvironment (TME), including metabolic crosstalk. We have previously shown that ex vivo tumor tissue cultures derived from ovarian carcinoma (OvC) resections retain the TME components for at least four weeks of culture and implemented assays for assessment of drug response. Here, we explored ex vivo patient-derived tumor tissue cultures to uncover metabolic signatures of chemosensitivity and/or resistance. Tissue cultures derived from nine OvC cases were challenged with carboplatin and paclitaxel, the standard-of-care chemotherapeutics, and the metabolic footprints were characterized by LC-MS. Partial least-squares discriminant analysis (PLS-DA) revealed metabolic signatures that discriminated high-responder from low-responder tissue cultures to ex vivo drug exposure. As a proof-of-concept, a set of potential metabolic biomarkers of drug response was identified based on the receiver operating characteristics (ROC) curve, comprising amino acids, fatty acids, pyrimidine, glutathione, and TCA cycle pathways. Overall, this work establishes an analytical and computational platform to explore metabolic features of the TME associated with response to treatment, which can leverage the discovery of biomarkers of drug response and resistance in OvC.

Low-Intensity Focused Ultrasound Targeted Microbubble Destruction Enhanced Paclitaxel Sensitivity by Decreasing Autophagy in Paclitaxel-Resistant Ovarian Cancer.

Ultrasound targeted microbubble destruction (UTMD) was introduced as a promising method to improve anti-tumor therapeutic efficacy, while minimizing side effects to healthy tissues. Nevertheless, the acoustical phenomenon behind the UTMD as well as the exact mechanisms of autophagy action involved in the increased anti-cancer response are still not fully understood. Therefore, we examined the drug resistance-reversing effects of low-intensity focused ultrasound with microbubble (LIFU+MB) in paclitaxel (PTX)-resistant ovarian cancer cells. Cell viability was evaluated using CCK8 (Cell Counting Kit-8), apoptosis was detected by flow cytometry, quantitative real-time PCR and Western blot were used to detect the expressions of mRNA and protein, and autophagy was observed by transmission electron microscopy (TEM). We revealed that the level of autophagy was increased (p < 0.05) in PTX-resistant ovarian cancer cells. Treatment of LIFU+MB combined with PTX can notably inhibit proliferation as well as increase apoptosis (p < 0.01) in drug-resistant cells. We proposed that LIFU+MB might affect the sensitivity of ovarian cancer cells to PTX by modulating autophagy. To verify the hypothesis, we analyzed the autophagy level of drug-resistant cells after the treatment of LIFU+MB and found that autophagy was significantly inhibited. Altogether, our findings demonstrated that LIFU+MB could reverse PTX resistance in ovarian cancer via inhibiting autophagy, which provides a novel strategy to improve chemosensitivity in ovarian cancer.

Identification of Hub Genes for Ovarian Cancer Stem Cell Properties with Weighted Gene Co-expression Network Analysis

To investigate the significance of stemness-related genes in the diagnosis and treatment of ovarian cancer. Key modules and genes were identified with weighted gene co-expression network analysis (WGCNA). The signal pathways of high expression of key genes were analyzed by gene set enrichment analysis (GSEA) and single cell sequencing data. The chemosensitivity of ovarian cancer to chemotherapy drugs was estimated with pRRophetic. Flow cytometry was used to examine the expression of CD44 +CD117 +in SKOV3 cells and cancer stem cells. The expression of key genes in ovarian cancer stem cells was confirmed by qRT-PCR. The core genes were identified by GeneMANIA analysis. According to the WGCNA results, 15 key genes were identified at the transcription level, all being highly expressed in many kinds of tumors. They were involved in the cell cycle, DNA repair, E2 target and G2M checkpoint pathway, and had significant correlation with chemosensitivity. The proportion of CD44 + CD117 + cells in SKOV3 cells and ovarian cancer stem cells were (1.20±0.34)% and (37.17±1.80)% respectively, with statistically significant difference ( P<0.05). qRT-PCR confirmed that seven key genes ( BUB1, CDC20, CCNB2, DLGAP5, KIF4 A, NEK2, NUSAP1) in the WGCNA results were highly expressed in ovarian cancer stem cells, and BUB1 might have played a core role. Seven hub genes, especially BUB1, were identified by constructing gene co-expression network, which may become potential biomarkers of ovarian cancer gene.

ERCC1 expression and platinum chemosensitivity in patients with ovarian cancer: A meta-analysis.

This study aimed to comprehensively investigate the correlation of ERCC1 expression and chemosensitivity of ovarian cancer. The literature on the relationship between the excision repair cross complementary gene 1 (ERCC1) and the chemosensitivity of ovarian cancer published in PubMed, Web of Science, EMBASE, CNKI, and the China Wanfang database from the establishment of the databases to June 2020 were searched. Chemosensitivity is evaluated by clinical effective rate (complete remission plus partial remission). Statistical analysis was carried out by using Stata 15.1 software. A total of 11 articles met the inclusion criteria, consisting of 758 patients with ovarian cancer. The results showed a significant difference in chemosensitivity between the low expression group and the high expression group of ERCC1 (odds ratio 4.23; 95% confidence interval 2.96, 6.06; P < 0. 01). The same result was shown in the ethnicity subgroup. The chemosensitivity of ovarian cancer patients with a low expression of ERCC1 is better than that of patients with a high expression.

Abstract LB-364: Mesothelial cells promote ovarian cancer stemness and chemoresistance through osteopontin paracrine signaling

Abstract Aims: As mesothelial cells are a major stromal component of the ovarian cancer metastatic microenvironment, in this study we investigated the role of ovarian cancer-associated mesothelial cells (CAMs) on cancer responsiveness to chemotherapy and intrinsic-related cancer stemness properties. Methods: Indirect co-culture system that enables medium exchange between human primary serous-type ovarian cancer cells and primary CAMs isolated from patient ascites was employed, and these co-cultured cancer cells were subsequently grafted subcutaneously to NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice and received serial cisplatin challenges, or checked by Annexin V apoptosis assays and cell viability assays to determine chemosensitivity. In addition, patient derived tumor organoid cultures were compared between the addition of control and its paired primary CAM conditioned medium. In vivo limiting dilution assays and sphere formation assays were utilized to evaluate CAM regulated cancer stemness properties. Finally, a cytokine array on CAM conditioned medium was performed to identify the secreted factors mediating phenotypical changes, and RNA-sequencing analysis of co-cultured cancer cells was conducted to uncover the major events that underlie changed chemo-responsiveness. Results: Cancer cell response to platium-based chemotherapy was inhibited after indirect CAM co-culture or CAM conditioned medium priming, as evidenced both in vivo and in vitro. Organoid formation was drastically enhanced with the supplement of paired CAM conditioned medium, while no tumor organoid was well formed in control medium. These organoids in CAM conditioned medium group are positive for cancer stem cell markers. Correspondingly, CAMs induced a cancer stemness phenotype, as shown by increased tumor formation rate in limiting dilution assays and by strengthened sphere formation abilities in sphere formation assays. Through a cytokine array and functional validations, we pinpointed soluble osteopontin as a key mediator of CAM-responsive cancer stemness and chemoresistance, and it initiates paracrine signaling through the CD44 receptor on cancer cells. RNA-sequencing of ovarian cancer cells primed with CAMs revealed overexpression of multi-drug resistance-related ABC-binding cassette transporters (ABC transporters). Lastly, genetic inhibition of osteopontin in CAMs with shRNA constructs and therapeutic targeting with an anti-osteopontin neutralizing antibody reduced cancer stemness and chemoresistance. Conclusions: We demonstrated that CAMs promote ovarian cancer chemoresistance and tumor formation by establishing a cancer stem cell niche. Importantly, our study identified paracrine osteopontin signaling as a critical mediator of chemoresistance and stemness, and targeting osteopontin from CAMs holds the potential to restore ovarian cancer chemosensitivity. Citation Format: Jin Qian, Bauer LeSavage, Chenkai Ma, Suchitra Natarajan, Joshua Eggold, Kelsea Hubka, Yiren Xiao, Katherine Fuh, Venkatesh Krishnan, Annika Enejder, Sarah Heilshorn, Oliver Dorigo, Erinn Rankin. Mesothelial cells promote ovarian cancer stemness and chemoresistance through osteopontin paracrine signaling [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-364.

Abstract A76: Role of frizzled-7 in platinum tolerance ovarian cancer

Abstract While ovarian cancer (OC) is considered as a highly chemoresponsive tumor, 75% women experience tumor relapse associated with chemoresistance. It has been hypothesized that ovarian cancer stem cells (OCSCs) are responsible for developing chemoresistant recurrent tumors and sharing characteristics with normal SCs. Measuring aldehyde dehydrogenase 1 (ALDH1) enzymatic activity has been demonstrated as an established method for OCSC identification and isolation. Our previous studies indicated that while chemotherapy initially “debulks” the mass of OC, residual tumors are enriched in OCSCs. Here, we aimed to identify new markers for CSC enriched platinum-resistant OCs using in vitro and in vivo models. We found that the surviving cells after repeated treatment with platinum were enriched in ALDH(+) cells, formed more spheroids and contained cells expressing CSC-related transcription factors (Sox 2) compared to parental cells, supporting that repeated platinum treatment selects cells with stem-like properties. Next, CSC RT-PCR based platform was used to compare wild-type and chemoresistant OCs and to rule out candidate genes that may drive stemness and chemoresistance. CSC array showed that Frizzled 7 receptor (FZD7), a transmembrane receptor involved in canonical Wnt/β-catenin, emerged as a top highly expressed marker in platinum-resistant compared to parental cells and was next studied as a putative new marker for CSC-enriched chemoresistant OCs. FZD7 expression was increased in platinum-resistant cells compared to parental cells at mRNA and protein levels. FZD7(+) cells were detectable and represent ~2-15% on OC cell lines and cells dissociated from human tumors. FZD7(+) population enriched in the platinum-resistant OCs and xenografts. In addition, KD FZD7 in chemoresistant OC cells restored chemosensitivity of OCs, decreased spheroid formation, and delayed tumor initiation, suggesting the role of FZD7 in regulating chemoresistance and stemness of OCs. RNA sequencing results of FZD7(+)/FZD7(-) OCs revealed that FZD7(+) cells downregulated genes associated to DNA damage response, and upregulated “persister cells” related genes, including EMT and stemness-associated genes. Importantly, mitochondrial dysfunction and oxidative phosphorylation were enriched in FZD7(-) OCs compared with FZD7(+) cells. As “persister cells” have been demonstrated to be dependent on antioxidant protein, glutathione peroxidase 4 (GPX4), for cell survival and maintaining mitochondrial oxidative phosphorylation in other cancer models, we checked GPX4 expression in FZD7(+) OCs and platinum-resistant OCs; the expression of GPX4 is correlated with FZD7 expression associated with chemoresistance. Platinum-resistant cells are more sensitive to GPX4 inhibitor treatment and KD FZD7 decreased GPX4 expression and blunt sensitivity of OCs to GPX4 inhibitor treatment, further supporting that platinum-resistant OCs are “persister like cells,” which are protected by GPX4 from lipid peroxidation stress and ferroptosis. Citation Format: Yinu Wang, Guanyuan Zhao, Hao Huang, Salvatore Condello, Jianjun Wei, Daniela Matei. Role of frizzled-7 in platinum tolerance ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr A76.

Synergistic enhancement of efficacy of platinum drugs with verteporfin in ovarian cancer cells

BackgroundEpithelial ovarian cancers (EOCs) comprises the majority of malignant ovarian neoplasms. Combination treatment with chemotherapeutic agents seems to be a promising strategy in ovarian cancer (OVCA) patients in order to overcome drug resistance. In this in vitro study, we investigated the therapeutic efficacy of verteporfin (VP) alone and in combination with cisplatin (CDDP), carboplatin (CP) and paclitaxel (Taxol). The main objectives of this study are to determine the nature of interactions between VP and CDDP/CP/Taxol and to understand the mechanism of action of VP in OVCA cells.MethodsThe efficacy of VP on cell proliferation, cytotoxicity, invasion and clonogenic capacity was assayed in CDDP-sensitive (COV504, OV-90) and CDDP-resistant (A2780Cis) cell lines. The cytotoxic effects of drugs either alone or in combination were evaluated using MTT assay and Cell Viability Blue assay. The effects of drugs on the metabolic functions were studied using matrigel invasion assay and clonogenic assay. Immunoblot analysis was carried out to investigate changes in YAP and cell cycle genes. Changes in the cytokines due to drug treatments were analyzed using a cytokine array.ResultsTreatment with VP inhibited cell proliferation, invasion and increased cytotoxicity of OVCA cells. We observed that VP chemosensitized CDDP-resistant cells, even at lower doses. When added either in constant or non-constant ratios, VP produced synergistic effects in combination with CDDP/CP/Taxol. A cytokine array identified upregulation of cytokines in OVCA cells that were inhibited by VP treatment.ConclusionsEither in cisplatin-resistant cell lines or cisplatin-sensitive cell lines, VP proves to be more efficient in inhibiting cell proliferation and inducing cytotoxicity. Our results suggest that novel combinations of VP with CDDP or CP or Taxol might be an attractive therapeutic strategy to enhance OVCA chemosensitivity. The fact that lower doses of VP are effective in chemosensitizing the CDDP-resistant cells, might ultimately lead to the development of an innovative combination therapy for the treatment of OVCA patients.

Ivermectin Augments the In Vitro and In Vivo Efficacy of Cisplatin in Epithelial Ovarian Cancer by Suppressing Akt/mTOR Signaling

BackgroundThe poor outcomes in epithelial ovarian cancer necessitate new treatments. In this work, we systematically analyzed the inhibitory effects of ivermectin and the molecular mechanism of its action in ovarian cancer. MethodsThe effects of ivermectin alone and its combination with cisplatin on growth and survival were examined using cultured ovarian cancer cells and a xenograft mouse model. The molecular mechanism of action of ivermectin, focusing on Akt/mTOR signaling, was elucidated. ResultsIvermectin arrested growth in the G2/M phase and induced caspase-dependent apoptosis in ovarian cancer, regardless of specific cellular and molecular differences. Ivermectin significantly augmented the inhibitory effect of cisplatin on ovarian cancer cells in a dose-dependent manner. Mechanistically, ivermectin suppressed the phosphorylation of key molecules in the Akt/mTOR signaling pathway in ovarian cancer cells. In addition, overexpression of constitutively active Akt restored ivermectin-induced inhibition of Akt/mTOR, growth arrest and apoptosis. In an ovarian cancer xenograft mouse model, ivermectin alone significantly inhibited tumor growth. In combination with cisplatin, tumor growth was completely reversed over the entire duration of drug treatment without any toxicity. Furthermore, the concentrations of ivermectin used in our study are pharmacologically achievable. ConclusionsOur work suggests that ivermectin may be a useful addition to the treatment armamentarium for ovarian cancer and that targeting Akt/mTOR signaling is a therapeutic strategy to increase chemosensitivity in ovarian cancer.

MLH1 Is a Prognostic Biomarker for Serous Ovarian Cancer Treated With Platinum- and Taxane-based Chemotherapy.

The potential of the DNA mismatch repair (MMR) system as a prognostic predictor has been evaluated in several cancer types. However, associations between MMR and the prognostic factors of ovarian cancer are poorly understood. MLH1 expression was evaluated by immunohistochemistry in patients with advanced serous ovarian cancer treated with platinum- and taxane-based chemotherapy. Associations between MLH1 expression and clinicopathological factors as well as claudin-4 expression were examined. Low MLH1 expression was significantly associated with increased progression-free and overall survival, and a normalisation of CA125 levels after chemotherapy. Additionally, low claudin-4 expression was more frequently found among the group with low MLH1 expression. Low MLH1 expression was associated with improved prognosis and is a possible predictor of the chemosensitivity of ovarian cancer. Claudin-4 might be involved in the molecular mechanisms underlying how MLH1 influences survival and chemosensitivity in patients with ovarian cancer.

P53 Promotes chemoresponsiveness by regulating hexokinase II gene transcription and metabolic reprogramming in epithelial ovarian cancer.

Metabolic reprogramming (including the Warburg effect) is a hallmark of cancer, yet the association between the altered metabolism and chemoresistance remains elusive. Hexokinase II (HKII) is a key metabolic enzyme and is upregulated in multiple cancers. In this study, we examined the impact of targeting metabolism via silencing of HKII on chemoresistance in ovarian cancer (OVCA). In addition, the regulatory molecular mechanism of tumor metabolism was examined using gain- and loss-of-function approaches in epithelial OVCA cell lines of various histological subtypes. We demonstrated that cisplatin (CDDP)-induced p53-mediated HKII downregulation is a determinant of chemosensitivity in OVCA. Silencing of HKII sensitized chemoresistant OVCA cells to apoptosis in a p53-dependent manner. As a negative regulator, p53 suppressed HKII transcription by promoter binding and decreased glycolysis. Pyruvate dehydrogenase kinase-1 (PDK1) is a key regulator of cell proliferation involved in Akt signaling axis. Our Gene Expression Profiling Interactive Analysis (GEPIA) and molecular studies also revealed that PDK1, an upstream activator strongly correlates with HKII expression and regulates its metabolic activity. Finally, we demonstrated that the clinically approved drug metformin sensitizes chemoresistant OVCA cells to CDDP via PDK1-HKII pathway. Collectively, our data implicate that p53--PDK1-HKII axis is a central regulatory component of metabolism conferring chemoresistance in OVCA.

The iron chelator desferrioxamine synergizes with chemotherapy for cancer treatment

BackgroundCisplatin (CDDP) resistance remains a major obstacle for treatment of ovarian cancer. Iron contributes to the growth and reproduction of malignant cells, thus iron chalators can inhibit the growth of tumor cells by depleting the intracellular iron pool. The iron chelator, desferrioxamine (DFO), has performed anticancer in previous study. The aim of our study is to determine the correlation between iron-deprivation and tumor chemosensitivity in ovarian cancer. MethodsTo investigate the prognostic value of ferritin light (FTL), ferroportin (FPN), hepcidin (HAMP) and divalent metal-ion transporter-1 (DMT1) in ovarian cancer, the Kaplan–Meier analysis and the Gene Expression Profiling Interactive Analysis (GEPIA) were used. The ovarian cancer cell lines (SKOV-3 and OVCAR-3) were exposed to a gradient concentration of DFO (10, 20, 50, 100, 200 μM) and CDDP (1, 5, 10, 50,100 μM) for 24 h. The protein expression of FTL was tested. The expression of cancer stem cell (CSC) markers, including Sox2, Nanog and C-myc, were downregulated with treatment of DFO. Also, the mamosphere formation and the plation of CD44+/high/CD133+/high and Aldehyde dehydrogenase (ALDH)+/high SKOV-3 cells were reduced after treatment for 7d. Furthermore, we detected the expression of p53, BCL-2, BAX, and caspase-8. ResultsThe survival analysis revealed that high expression of FTL, DMT1, HAMP, showed poor overall survival (OS) in ovarian cancer patients. Our combined data found that DFO could effectively inhibit CSCs, improve the resistance to chemotherapy, and significantly enhanced the efficacy of CDDP therapy in vitro in promoting apoptosis. Besides, targeting molecular targets, including BAX, BCL-2, p53 and caspase-8 could serve as the clinical biomarkers to evaluate the effects of ovarian cancer. It is reasonable to believe that DFO adjuvant therapy in combination with CDDP chemotherapy can promote the improvement of treatment response in ovarian cancer patients. ConclusionOur research suggests the experimental evidence for DFO and CDDP as a new effective combination therapy to enhance the efficacy of chemical therapy in ovarian cancer.

MiR-211 facilitates platinum chemosensitivity by blocking the DNA damage response (DDR) in ovarian cancer

The DNA damage response (DDR) is one of the most important mechanisms of platinum resistance in ovarian cancer. Some miRNAs have been identified to be involved in the regulatory network of DDR, thus the abnormal expression of miRNAs might affect platinum chemosensitivity in ovarian cancer. In this study, by assessing miRNAs simultaneously targeting a set of DDR genes that exhibited response to platinum, we found that miR-211 inhibited most of those genes, and proposed that miR-211 might affect the sensitivity of ovarian cancer cells to platinum by targeting multiple DDR genes and thereby determine the prognosis of ovarian cancer. To verify the hypothesis, we analyzed the association between miR-211 level and clinical prognosis, assessed the effect of miR-211 on DDR and platinum chemosensitivity, and explored the possible molecular mechanism. We revealed that miR-211 enhanced platinum chemosensitivity and was positively correlated with favorable outcomes in ovarian cancer patients. Many DDR genes including TDP1 were identified as targets of miR-211. In contrast, TDP1 suppressed DNA damage and platinum chemosensitivity. Moreover, the miR-211 level in tissues was shown to be associated with the good outcome of neoadjuvant chemotherapy and negatively correlated with the expression of TDP1. Conclusively, we demonstrated that miR-211 improves the prognosis of ovarian cancer patients by enhancing the chemosensitivity of cancer cells to platinum via inhibiting DDR gene expression, which provides an essential basis to identify novel treatment targets to block DDR effectively and improve chemosensitivity in ovarian cancer.

MiR-374b-5p-FOXP1 feedback loop regulates cell migration, epithelial-mesenchymal transition and chemosensitivity in ovarian cancer

MicroRNAs (miRNAs) are important regulators in tumorigenesis and progression of multiple human cancers, including ovarian cancer (OC). As a member of miRNAs family, miR-374b-5p has been reported to be a tumor suppressive gene in human cancers. In this study, the lower expression of miR-374b-5p was identified in OC tissues and cell liens using quantitative real time PCR (qRT-PCR). Forkhead box protein P1 (FOXP1) can act as an oncogene in human cancers. Mechanism experiments revealed that FOXP1 is a target of miR-374b-5p. Functionally, miR-374b-5p suppressed cell proliferation, migration and epithelial-mesenchymal transition (EMT) in ovarian cancer. Moreover, the sensitivity of OC cells to cisplatin was markedly enhanced by miR-374b-5p. However, FOXP1 reversed However, FOXP1 reversed miR-374b-5p-mediated biological functions. Previous reports demonstrated the inhibitory effect of FOXP1 on transcription FOXP1. Thus, we further examined the effect of FOXP1 on the transcription activity of miR-374b-5p in OC cells. The results showed that FOXP1 decreased miR-374b-5p expression by inhibiting the transcription activity of miR-374b-5p. Rescue assays revealed the regulatory effect of miR-374b-5p-FOXP1 feedback loop on ovarian cancer progression. In conclusion, miR-374b-5p-FOXP1 feedback loop regulates tumor progression and chemosensitivity in ovarian cancer.

PML-Regulated Mitochondrial Metabolism Enhances Chemosensitivity in Human Ovarian Cancers

SummaryHigh-grade serous ovarian cancer (HGSOC) remains an unmet medical challenge. Here, we unravel an unanticipated metabolic heterogeneity in HGSOC. By combining proteomic, metabolomic, and bioergenetic analyses, we identify two molecular subgroups, low- and high-OXPHOS. While low-OXPHOS exhibit a glycolytic metabolism, high-OXPHOS HGSOCs rely on oxidative phosphorylation, supported by glutamine and fatty acid oxidation, and show chronic oxidative stress. We identify an important role for the PML-PGC-1α axis in the metabolic features of high-OXPHOS HGSOC. In high-OXPHOS tumors, chronic oxidative stress promotes aggregation of PML-nuclear bodies, resulting in activation of the transcriptional co-activator PGC-1α. Active PGC-1α increases synthesis of electron transport chain complexes, thereby promoting mitochondrial respiration. Importantly, high-OXPHOS HGSOCs exhibit increased response to conventional chemotherapies, in which increased oxidative stress, PML, and potentially ferroptosis play key functions. Collectively, our data establish a stress-mediated PML-PGC-1α-dependent mechanism that promotes OXPHOS metabolism and chemosensitivity in ovarian cancer.

Coexpression network analysis identified Krüppel-like factor 6 (KLF6) association with chemosensitivity in ovarian cancer.

Although most patients with ovarian cancer (OC) are initially sensitive to paclitaxel/carboplatin combination chemotherapy, eventually they develop resistance to chemotherapy drugs and experience disease relapse. OC is the most lethal gynecological malignancy, and the five-year survival rate is extremely low. Thus, research on specific biomarkers and potential targets for chemotherapy-resistant patients with OC is needed. In our study, genes in the top 10% of variance in data set GSE30161 from chemoresistant and chemosensitive OC tissues were determined to conduct a weighted gene coexpression network analysis (WGCNA). The magenta module was most strongly related to OC chemoresponse. Gene ontology enrichment analysis indicated that the function of the magenta module primarily focused on transcription regulation, cell cycle control, and apoptosis modulation. Integration of the WGCN with the protein-protein interaction network identified five candidate genes. These five genes were verified using the GSE51373 test set, and Krüppel-like factor 6 ( KLF6) was identified as tightly linked to OC chemosensitivity. The receiver operating characteristic (ROC) curve showed that KLF6 differentiated chemoresistant from chemosensitive OC tissues. The Kaplan-Meier online database indicated that high KLF6 expression was associated with poor OC prognosis. Gene set enrichment analysis determined that the KLF6 mechanism was potentially associated with cell cycle, mTOR, and DNA-damage repair signaling pathways. In conclusion, KLF6 was identified in association with OC chemoresistance, and the mechanism of KLF6-mediated chemoresistance may involve the cell cycle, mTOR, and DNA-damage repair signaling pathways.