scholarly journals Group III phospholipase A2 downregulation attenuated survival and metastasis in ovarian cancer and promotes chemo-sensitization

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Upasana Ray ◽  
Debarshi Roy ◽  
Ling Jin ◽  
Prabhu Thirusangu ◽  
Julie Staub ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cell Viability ◽  
Phospholipase A2 ◽  
Mtt Assay ◽  
Metabolic Inhibitor ◽  
Autophagic Flux ◽  
Ciliated Cells ◽  
Group Iii

Abstract Background Aberrant lipogenicity and deregulated autophagy are common in most advanced human cancer and therapeutic strategies to exploit these pathways are currently under consideration. Group III Phospholipase A2 (sPLA2-III/PLA2G3), an atypical secretory PLA2, is recognized as a regulator of lipid metabolism associated with oncogenesis. Though recent studies reveal that high PLA2G3 expression significantly correlates with poor prognosis in several cancers, however, role of PLA2G3 in ovarian cancer (OC) pathogenesis is still undetermined. Methods CRISPR-Cas9 and shRNA mediated knockout and knockdown of PLA2G3 in OC cells were used to evaluate lipid droplet (LD) biogenesis by confocal and Transmission electron microscopy analysis, and the cell viability and sensitization of the cells to platinum-mediated cytotoxicity by MTT assay. Regulation of primary ciliation by PLA2G3 downregulation both genetically and by metabolic inhibitor PFK-158 induced autophagy was assessed by immunofluorescence-based confocal analysis and immunoblot. Transient transfection with GFP-RFP-LC3B and confocal analysis was used to assess the autophagic flux in OC cells. PLA2G3 knockout OVCAR5 xenograft in combination with carboplatin on tumor growth and metastasis was assessed in vivo. Efficacy of PFK158 alone and with platinum drugs was determined in patient-derived primary ascites cultures expressing PLA2G3 by MTT assay and immunoblot analysis. Results Downregulation of PLA2G3 in OVCAR8 and 5 cells inhibited LD biogenesis, decreased growth and sensitized cells to platinum drug mediated cytotoxicity in vitro and in in vivo OVCAR5 xenograft. PLA2G3 knockdown in HeyA8MDR-resistant cells showed sensitivity to carboplatin treatment. We found that both PFK158 inhibitor-mediated and genetic downregulation of PLA2G3 resulted in increased number of percent ciliated cells and inhibited cancer progression. Mechanistically, we found that PFK158-induced autophagy targeted PLA2G3 to restore primary cilia in OC cells. Of clinical relevance, PFK158 also induces percent ciliated cells in human-derived primary ascites cells and reduces cell viability with sensitization to chemotherapy. Conclusions Taken together, our study for the first time emphasizes the role of PLA2G3 in regulating the OC metastasis. This study further suggests the therapeutic potential of targeting phospholipases and/or restoration of PC for future OC treatment and the critical role of PLA2G3 in regulating ciliary function by coordinating interface between lipogenesis and metastasis.

scholarly journals Abrogation of group III phospholipase A2 inhibits tumor growth and metastasis in ovarian cancer and promotes chemo-sensitization

2021 ◽  
Author(s):  
Upasana Ray ◽  
Debarshi Roy ◽  
Ling Jin ◽  
Prabhu Thirusangu ◽  
Julie Staub ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Tumor Growth ◽  
Cell Viability ◽  
Phospholipase A2 ◽  
Mtt Assay ◽  
Ciliated Cells ◽  
Group Iii ◽  
Tumor Growth And Metastasis

Abstract Background Aberrant lipogenicity and deregulated autophagy are common in most advanced human cancer and therapeutic strategies to exploit these pathways are currently under consideration. Group III Phospholipase A2 (sPLA2-III/PLA2G3), an atypical secretory PLA2, is recognized as a regulator of lipid metabolism associated with oncogenesis. Though recent studies reveal that high PLA2G3 expression significantly correlates with poor prognosis in several cancers, however, role of PLA2G3 in ovarian cancer (OC) pathogenesis is still undetermined. Methods CRISPR-Cas9 and shRNA mediated knockout and knockdown of PLA2G3 in OC cells were used to evaluate lipid droplet (LD) biogenesis by confocal and Transmission electron microscopy analysis, and the cell viability and sensitization of the cells to platinum-mediated cytotoxicity by MTT assay. Regulation of primary ciliation by PLA2G3 downregulation both genetically and by metabolic inhibitor PFK-158 induced autophagy was assessed by immunofluorescence-based confocal analysis and immunoblot. Transient transfection with GFP-RFP-LC3B and confocal analysis was used to assess the autophagic flux in OC cells. PLA2G3 knockout OVCAR5 xenograft in combination with carboplatin on tumor growth and metastasis was assessed in vivo. Efficacy of PFK158 alone and with platinum drugs was determined in patient-derived primary ascites cultures expressing PLA2G3 by MTT assay and immunoblot analysis. Results Downregulation of PLA2G3 in OVCAR8 and 5 cells inhibited LD biogenesis, decreased growth and sensitized cells to platinum drug mediated cytotoxicity in vitro and in in vivo OVCAR5 xenograft. PLA2G3 knockdown in HeyA8MDR-resistant cells showed sensitivity to carboplatin treatment. We found that both PFK158 inhibitor-mediated and genetic downregulation of PLA2G3 resulted in increased number of percent ciliated cells and inhibited oncogenesis. Mechanistically, we found that PFK158-induced autophagy targeted PLA2G3 to restore primary cilia in OC cells. Of clinical relevance, PFK158 also induces percent ciliated cells in human-derived primary ascites cells and reduces cell viability with sensitization to chemotherapy. Conclusions Taken together, our study for the first time emphasizes the role of PLA2G3 in regulating the OC metastasis. This study further suggests the therapeutic potential of targeting phospholipases and/or restoration of PC for future OC treatment and the critical role of PLA2G3 in regulating ciliary function by coordinating interface between lipogenesis and metastasis.

scholarly journals The role of Sox6 and Netrin-1 in ovarian cancer cell growth, invasiveness, and angiogenesis

Tumor Biology ◽  
2017 ◽  
Vol 39 (5) ◽  
pp. 101042831770550 ◽  
Author(s):  
Yi Li ◽  
Ming Xiao ◽  
Fangchun Guo
Keyword(s):  
Ovarian Cancer ◽  
Cancer Cells ◽  
Conditioned Medium ◽  
Umbilical Vein ◽  
Inhibitory Effect ◽  
Ovarian Cancer Cells ◽  
Human Umbilical Vein ◽  
Tumor Tissues

SOX6 plays important roles in cell proliferation, differentiation, and cell fate determination. It has been confirmed that SOX6 is a tumor suppressor and downregulated in various cancers, including esophageal squamous cell carcinoma, hepatocellular carcinoma, and chronic myeloid leukemia. Netrin-1 is highly expressed in various human cancers and acts as an anti-apoptotic and proangiogenic factor to drive tumorigenesis. The role of SOX6 and netrin-1 in regulating the growth of ovarian tumor cells still remains unclear. Real-time polymerase chain reaction and western blot were used to determine the SOX6 messenger RNA and protein levels, respectively, in ovarian cancer cells and tumor tissues. Stable transfection of SOX6 was conducted to overexpress SOX6 in PA-1 and SW626 cells. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Invasion of ovarian cancer cells and migration of human umbilical vein endothelial cells were confirmed by Transwell assays. To overexpress netrin-1, ovarian cancer cells with SOX6 restoration was transduced with netrin-1 lentiviral particles. PA-1 xenografts in a nude mice model were used to conduct in vivo evaluation of the role of SOX6 and its relationship with netrin-1 in tumor growth and angiogenesis. In this study, we found significantly reduced SOX6 levels in PA-1, SW626, SK-OV-3, and CaoV-3 ovarian cancer cell lines and human tumor tissues in comparison with normal human ovarian epithelial cells or matched non-tumor tissues. SOX6 overexpression by stable transfection dramatically inhibited proliferation and invasion of PA-1 and SW626 cells. Also, conditioned medium from PA-1 and SW626 cells with SOX6 restoration exhibited reduced ability to induce human umbilical vein endothelial cells migration and tube formation compared with conditioned medium from the cells with transfection control. Furthermore, an inverse relationship between SOX6 and netrin-1 expression was observed in PA-1 and SW626 cells. Overexpression of netrin-1 in ovarian cancer cells with forced SOX6 expression remarkably abrogated the inhibitory effect of SOX6 on proliferation, invasion of the cells, and tumor xenograft growth and vascularity in vivo. Human umbilical vein endothelial cell migration and tube formation were enhanced in the conditioned medium from the ovarian cancer cells transduced with netrin-1 lentivirus particles. Our observations revealed that SOX6 is a tumor suppressor in ovarian cancer cells, and SOX6 exerts an inhibitory effect on the proliferation, invasion, and tumor cell-induced angiogenesis of ovarian cancer cells, whereas nerin-1 plays an opposite role and its expression is inversely correlated with SOX6. Moreover, our findings suggest a new role of SOX6 and netrin-1 for understanding the progression of ovarian cancer and have the potential for the development of new diagnosis and treatment strategies for ovarian cancer.

scholarly journals Role of microRNAs as Clinical Cancer Biomarkers for Ovarian Cancer: A Short Overview

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 169 ◽  
Author(s):  
Cristina Elena Staicu ◽  
Dragoș-Valentin Predescu ◽  
Călin Mircea Rusu ◽  
Beatrice Mihaela Radu ◽  
Dragos Cretoiu ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Simultaneous Detection ◽  
Clinical Signs ◽  
In Vivo Models ◽  
Circulating Micrornas ◽  
Clinical Biomarkers ◽  
Molecular Clustering

Ovarian cancer has the highest mortality rate among gynecological cancers. Early clinical signs are missing and there is an urgent need to establish early diagnosis biomarkers. MicroRNAs are promising biomarkers in this respect. In this paper, we review the most recent advances regarding the alterations of microRNAs in ovarian cancer. We have briefly described the contribution of miRNAs in the mechanisms of ovarian cancer invasion, metastasis, and chemotherapy sensitivity. We have also summarized the alterations underwent by microRNAs in solid ovarian tumors, in animal models for ovarian cancer, and in various ovarian cancer cell lines as compared to previous reviews that were only focused the circulating microRNAs as biomarkers. In this context, we consider that the biomarker screening should not be limited to circulating microRNAs per se, but rather to the simultaneous detection of the same microRNA alteration in solid tumors, in order to understand the differences between the detection of nucleic acids in early vs. late stages of cancer. Moreover, in vitro and in vivo models should also validate these microRNAs, which could be very helpful as preclinical testing platforms for pharmacological and/or molecular genetic approaches targeting microRNAs. The enormous quantity of data produced by preclinical and clinical studies regarding the role of microRNAs that act synergistically in tumorigenesis mechanisms that are associated with ovarian cancer subtypes, should be gathered, integrated, and compared by adequate methods, including molecular clustering. In this respect, molecular clustering analysis should contribute to the discovery of best biomarkers-based microRNAs assays that will enable rapid, efficient, and cost-effective detection of ovarian cancer in early stages. In conclusion, identifying the appropriate microRNAs as clinical biomarkers in ovarian cancer might improve the life quality of patients.

scholarly journals New Actors Driving the Epithelial–Mesenchymal Transition in Cancer: The Role of Leptin

Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1676
Author(s):  
Monserrat Olea-Flores ◽  
Juan C. Juárez-Cruz ◽  
Miriam D. Zuñiga-Eulogio ◽  
Erika Acosta ◽  
Eduardo García-Rodríguez ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Tumor Progression ◽  
Epithelial Mesenchymal Transition ◽  
Migration And Invasion ◽  
Mesenchymal Transition ◽  
Epithelial Cancers ◽  
Patients With Cancer

Leptin is a hormone secreted mainly by adipocytes; physiologically, it participates in the control of appetite and energy expenditure. However, it has also been linked to tumor progression in different epithelial cancers. In this review, we describe the effect of leptin on epithelial–mesenchymal transition (EMT) markers in different study models, including in vitro, in vivo, and patient studies and in various types of cancer, including breast, prostate, lung, and ovarian cancer. The different studies report that leptin promotes the expression of mesenchymal markers and a decrease in epithelial markers, in addition to promoting EMT-related processes such as cell migration and invasion and poor prognosis in patients with cancer. Finally, we report that leptin has the greatest biological relevance in EMT and tumor progression in breast, lung, prostate, esophageal, and ovarian cancer. This relationship could be due to the key role played by the enriched tumor microenvironment in adipose tissue. Together, these findings demonstrate that leptin is a key biomolecule that drives EMT and metastasis in cancer.

scholarly journals METTL3 promotes the initiation and metastasis of ovarian cancer by inhibiting CCNG2 expression via promoting the maturation of pri-microRNA-1246

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xuehan Bi ◽  
Xiao Lv ◽  
Dajiang Liu ◽  
Hongtao Guo ◽  
Guang Yao ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Molecular Mechanisms ◽  
High Expression ◽  
Ovarian Cancer Cells ◽  
Inadequate Knowledge ◽  
And Migration ◽  
Cancer Tissues

AbstractOvarian cancer is a common gynecological malignant tumor with a high mortality rate and poor prognosis. There is inadequate knowledge of the molecular mechanisms underlying ovarian cancer. We examined the expression of methyltransferase-like 3 (METTL3) in tumor specimens using RT-qPCR, immunohistochemistry, and Western blot analysis, and tested the methylation of METTL3 by MSP. Levels of METTL3, miR-1246, pri-miR-1246 and CCNG2 were then analyzed and their effects on cell biological processes were also investigated, using in vivo assay to validate the in vitro findings. METTL3 showed hypomethylation and high expression in ovarian cancer tissues and cells. Hypomethylation of METTL3 was pronounced in ovarian cancer samples, which was negatively associated with patient survival. Decreased METTL3 inhibited the proliferation and migration of ovarian cancer cells and promoted apoptosis, while METTL3 overexpression exerted opposite effects. Mechanistically, METTL3 aggravated ovarian cancer by targeting miR-1246, while miR-1246 targeted and inhibited CCNG2 expression. High expression of METTL3 downregulated CCNG2, promoted the metabolism and growth of transplanted tumors in nude mice, and inhibited apoptosis. The current study highlights the promoting role of METTL3 in the development of ovarian cancer, and presents new targets for its treatment.

scholarly journals Novel role of lncRNA CHRF in cisplatin resistance of ovarian cancer is mediated by miR-10b induced EMT and STAT3 signaling

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wen-Xi Tan ◽  
Ge Sun ◽  
Meng-Yuan Shangguan ◽  
Zhi Gui ◽  
Yang Bao ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cisplatin Resistance ◽  
Gynecological Cancer ◽  
Acquired Resistance ◽  
Tumor Burden ◽  
Human Patient ◽  
Mesenchymal Transition ◽  
Stat3 Signaling

Abstract Ovarian Cancer (OC) is a highly lethal gynecological cancer which often progresses through acquired resistance against the administered therapy. Cisplatin is a common therapeutic for the treatment of OC patients and therefore it is critical to understand the mechanisms of resistance against this drug. We studied a paired cell line consisting of parental and cisplatin resistant (CR) derivative ES2 OC cells, and found a number of dysregulated lncRNAs, with CHRF being the most significantly upregulated lncRNA in CR ES2 cells. The findings corroborated in human patient samples and CHRF was significantly elevated in OC patients with resistant disease. CHRF was also found to be elevated in patients with liver metastasis. miR-10b was found to be mechanistically involved in CHRF mediated cisplatin resistance. It induced resistance in not only ES2 but also OVCAR and SKOV3 OC cells. Induction of epithelial-to-mesenchymal-transition (EMT) and activation of STAT3 signaling were determined to be the mechanisms underlying the CHRF-miR-10b axis-mediated cisplatin resistance. Down-regulation of CHRF reversed EMT, STAT3 activation and the resulting cisplatin resistance, which could be attenuated by miR-10b. The results were also validated in an in vivo cisplatin resistance model wherein CR cells were associated with increased tumor burden, CHRF downregulation associated with decreased tumor burden and miR-10b again attenuated the CHRF downregulation effects. Our results support a novel role of lncRNA CHRF in cisplatin resistance of OC and establish CHRF-miR-10b signaling as a putative therapeutic target for sensitizing resistant OC cells.

Complement Component 3 (C3) Is a Mediator of Epithelial-Mesenchymal Transition (EMT)

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1421-1421
Author(s):  
Min Soon Cho ◽  
Qianghua Hu ◽  
Rajesha Rupaimoole ◽  
Anil Sood ◽  
Vahid Afshar-Kharghan
Keyword(s):  
Ovarian Cancer ◽  
Cancer Cells ◽  
Epithelial Mesenchymal Transition ◽  
Malignant Tumors ◽  
Mouse Embryos ◽  
Ovarian Cancer Cells ◽  
Mesenchymal Transition ◽  
E Cadherin

Abstract We have shown that complement component 3 (C3) is expressed in malignant ovarian epithelial cells and enhances cell proliferation in vitro and tumor growth in vivo. C3 is secreted by cancer cells into the tumor microenvironment and promotes tumor growth through an autocrine loop. To understand the mechanism of upregulation of C3 expression in malignant epithelial cells, we studied the transcriptional regulation of C3, and found that TWIST1, a major regulator of EMT, binds to the C3 promoter and regulates C3 transcription. Knockdown of the TWIST1 gene reduced C3 mRNA, and TWIST1 overexpression increased C3 mRNA. TWIST1 promotes epithelial-mesenchymal transition (EMT) during normal development and in metastasis of malignant tumors. An important marker of EMT is a reduction in the surface expression of E-cadherin on cells facilitating migration and invasion of these cells. TWIST1 is a transcriptional repressor of E-cadherin; and because TWIST1 increases C3 expression, we investigated whether C3 is also a negative regulator of E-cadherin expression. We overexpressed C3 in ovarian cancer cells by stable transduction of lentivirus carrying C3 cDNA. Overexpression of C3 was associated with 32% reduction in the expression of E-cadherin resulting in enhanced migration ability of cells by 2.3 folds and invasiveness by 1.75 folds, as compared to control cells transduced with control lentivirus. To investigate whether TWIST1-induced reduction in E-cadherin is C3-mediated or not, we studied the effect of TWIST1 overexpression simultaneous with C3 knockdown in ovarian cancer cells. Overexpression of TWIST1 alone resulted in 70% reduction in E-cadherin mRNA and this was completely reversed after simultaneous C3 knockdown in these cells. To investigate the correlation between C3 and TWIST1 in vivo, we studied the co-expression of these two proteins in mouse embryos (physiologic EMT) and in malignant tumors (pathologic EMT). Given the role of EMT in embryogenesis we immunostained mouse embryos at different stages of development, using antibodies against TWIST1 or C3. Transverse section of 9.5-day post-coitum (9.5dpc) mouse embryos showed co-expression of TWIST1 and C3 in otocyst (ot) and hindbrain (hb) of neural crest. In the whole-mounted 11.5dpc mouse embryos, C3 and TWIST1 were co-expressed in limb buds. Given the role of EMT in malignancy, tumors induced in mice after intraperitoneal injection of murine ovarian cancer cells were resected and immunostained for C3 and TWIST1 proteins. TWIST1 and C3 co-localized at tumor edges, where EMT and tumor cells migration occur. Taken together, these data provide evidence that TWIST1 regulates C3 expression, and C3 promotes EMT through E-cadherin. Disclosures No relevant conflicts of interest to declare.

Effect of therapeutic GAS6/AXL inhibition of tumor and stromal cells on DNA damage and response to chemotherapy in ovarian cancer.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e14676-e14676 ◽  
Author(s):  
Mary M Mullen ◽  
Elena Lomonosova ◽  
Hollie M Noia ◽  
Lei Guo ◽  
Lindsay Midori Kuroki ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dna Damage ◽  
Neoadjuvant Chemotherapy ◽  
Cell Viability ◽  
Mouse Models ◽  
Stromal Cells ◽  
Predictive Biomarker ◽  
Response To Chemotherapy

e14676 Background: Ovarian cancer is the leading cause of death due to gynecologic malignancy. Biomarkers to predict chemoresponse and novel therapies to target these proteins would be practice changing. We aim to establish serum and tissue GAS6 as a predictive biomarker of chemoresponse and to determine if AXL inhibition through sequestration of its ligand, GAS6, with AVB-S6-500 (AVB) can improve chemoresponse. Methods: AVB was supplied by Aravive Biologics. High grade serous ovarian cancer (HGSOC) tumor samples were obtained pre- and post-neoadjuvant chemotherapy. AXL and GAS6 expression were evaluated by immunohistochemistry and serum concentration. In vitro viability and clonogenic assays were performed on chemoresistant tumor (OVCAR8, OVCAR5, COV62, and POV71-hTERT) and stromal cells (CAF86) treated with chemotherapy +/- AVB. Mouse models (OVCAR8, PDX, OVCAR5) were used to determine if the combination of chemotherapy + AVB reduced tumor burden. Immunofluorescent assays targeting ɣH2AX were used to evaluate DNA damage. Results: Patients with high pretreatment tumor GAS6 expression ( > 85%, n = 7) or serum GAS6 concentrations ( > 25ng/mL, n = 13) were more likely to be resistant to neoadjuvant chemotherapy than those with low tumor GAS6 expression ( < 45%, n = 4) (P = 0.010) or low serum GAS6 concentrations ( < 15ng/mL, n = 5) (P = 0.002). Carboplatin plus AVB (2µM, 5µM) and paclitaxel plus AVB (1µM) resulted in decreased cell viability and clonogenic growth compared to chemotherapy alone (p < 0.05) in all tumor and stromal cell lines. Synergism was seen between carboplatin+AVB and paclitaxel+AVB with a weighted combination index < 1. In vivo tumor mouse models treated with chemotherapy+AVB had significantly smaller subcutaneous and intraperitoneal (IP) tumors than those treated with chemotherapy alone (3.1mg vs 64mg, P = 0.003 OVCAR8; 62mg vs 157mg, P = 0.0108 PDX subcutaneous model; 0.05mg vs 0.3669mg, P < 0.001 OVCAR5 IP model). Increased DNA damage was noted in tumor and stromal cells treated with carboplatin+AVB compared to carboplatin alone (OVCAR8, COV362, CAF86 P < 0.001). Conclusions: High GAS6 is associated with lack of neoadjuvant chemoresponse in HGSOC patients. The combination of chemotherapy with AVB decreases tumor cell viability, tumor growth, and an increase in DNA damage response.

Role of glyoxalase-1 in trabectedin-resistant myxoid liposarcoma.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e23566-e23566
Author(s):  
Sonia Simonetti ◽  
Michele Iuliani ◽  
Francesco Pantano ◽  
Giulia Ribelli ◽  
Andrea Napolitano ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Viability ◽  
Cell Line ◽  
Myxoid Liposarcoma ◽  
Bioinformatics Analyses ◽  
In Vivo Models ◽  
Over Expression ◽  
Glyoxalase 1

e23566 Background: Glyoxalase-1 (Glo1) is involved in the detoxification of the endogenous reactive metabolite, methylglyoxal (MG), whose abnormal accumulation increases adduct levels and induce cell apoptosis. Previous studies demonstrated that increased Glo-1 expression was associated with cancer chemotherapy resistance. We performed bioinformatics analyses finding that Glo-1 mRNA over-expression was correlated with worse prognosis in patients affected by Soft Tissue Sarcoma (STS). On the bases of these evidences, we investigated the potential role of Glo1 expression as biomarker of tumor growth and drug resistance in STS. Methods: Trabectedin and MG cytoxicity was evaluated by MTT viability assay measured at spectrofluorometer. Apoptosis was analyzed by flow cytometry using Annexin V antibody and propidium iodide. Glo-1 expression analysis was performed by Western Blot using a mouse monoclonal anti-human Glo-1 antibody (NBP1-19015). Synergy analysis was calculated using Combenefit software and statistical analysis was performed by Student-t test using the program GraphPad-Prism. Results: As STS trabectedin resistant model, we used a myxoid-liposarcoma cell line (402-91 ET cells) that are not responsive to clinical doses of trabectedin contrary to the parental sensitive cell line (402-91 WT cells). Intriguingly, we found higher Glo-1 protein levels in 402-91 ET cells compared to 402-91 WT cells. The treatment of 402-91 ET cells with the specific Glo1 inhibitor S-p-bromobenzylglutathione cyclopentyl diester (BBGC), in combination with trabectedin (PharmaMar), significantly inhibited cell viability and increased apoptosis than trabectedin alone. In particular, the addition of BBGC reduced trabectedin EC50 (half-maximal effective concentration) from 20.4nM to 5.92nM in 402-91 ET cells, similar to that observed in 402-91 WT cells (4.92nM). To investigate if cell death was induced by MG accumulation following Glo1 inhibition, we evaluated 402-91 ET cell viability after treatment with different doses of MG in combination with trabectedin. The addition of MG restored sensitivity to trabectedin in 402-91 ET cells as well as BBGC. Conclusions: Our results highlight a new potential mechanism of trabectedin resistance mediated by Glo-1 over-expression. The use of the specific Glo-1 inhibitor, BBGC, restores trabectedin sensitivity in resistant cells leading to MG accumulation that, in turn, promotes cell death and apoptosis. These data provide a strong rationale to investigate Glo-1 inhibition strategy, in combination with trabectedin, in STS in vivo models.

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