Overcoming cisplatin resistance of ovarian cancer cells by targeting HIF-1-regulated cancer metabolism

Potential of natural products in osteosarcoma treatment: Focus on molecular mechanisms

Osteosarcoma is the most frequent type of bone cancer found in children and adolescents, and commonly arises in the metaphyseal region of tubular long bones. Standard therapeutic approaches, such as surgery, chemotherapy, and radiation therapy, are used in the management of osteosarcoma. In recent years, the mortality rate of osteosarcoma has decreased due to advances in treatment methods. Today, the scientific community is investigating the use of different naturally derived active principles against various types of cancer. Natural bioactive compounds can function against cancer cells in two ways. Firstly they can act as classical cytotoxic compounds by non-specifically affecting macromolecules, such as DNA, enzymes, and microtubules, which are also expressed in normal proliferating cells, but to a greater extent by cancer cells. Secondly, they can act against oncogenic signal transduction pathways, many of which are activated in cancer cells. Some bioactive plant-derived agents are gaining increasing attention because of their anti-cancer properties. Moreover, some naturally-derived compounds can significantly promote the effectiveness of standard chemotherapy drugs, and in certain cases are able to ameliorate drug-induced adverse effects caused by chemotherapy. In the present review we summarize the effects of various naturally-occurring bioactive compounds against osteosarcoma.

Insights into the Role of Oxidative Stress in Ovarian Cancer

Oxidative stress (OS) arises when the body is subjected to harmful endogenous or exogenous factors that overwhelm the antioxidant system. There is increasing evidence that OS is involved in a number of diseases, including ovarian cancer (OC). OC is the most lethal gynecological malignancy, and risk factors include genetic factors, age, infertility, nulliparity, microbial infections, obesity, smoking, etc. OS can promote the proliferation, metastasis, and therapy resistance of OC, while high levels of OS have cytotoxic effects and induce apoptosis in OC cells. This review focuses on the relationship between OS and the development of OC from four aspects: genetic alterations, signaling pathways, transcription factors, and the tumor microenvironment. Furthermore, strategies to target aberrant OS in OC are summarized and discussed, with a view to providing new ideas for clinical treatment.

Identification of Specific Cell Subpopulations and Marker Genes in Ovarian Cancer Using Single-Cell RNA Sequencing

Objective

Ovarian cancer is the deadliest gynaecological cancer globally. In our study, we aimed to analyze specific cell subpopulations and marker genes among ovarian cancer cells by single-cell RNA sequencing (RNA-seq).

Methods

Single-cell RNA-seq data of 66 high-grade serous ovarian cancer cells were employed from the Gene Expression Omnibus (GEO). Using the Seurat package, we performed quality control to remove cells with low quality. After normalization, we detected highly variable genes across the single cells. Then, principal component analysis (PCA) and cell clustering were performed. The marker genes in different cell clusters were detected. A total of 568 ovarian cancer samples and 8 normal ovarian samples were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed genes were identified according to ∣log2fold change (FC) | >1 and adjusted p value <0.05. To explore potential biological processes and pathways, functional enrichment analyses were performed. Furthermore, survival analyses of differentially expressed marker genes were performed.

Results

After normalization, 6000 highly variable genes were identified across the single cells. The cells were divided into 3 cell populations, including G1, G2M, and S cell cycles. A total of 1,124 differentially expressed genes were identified in ovarian cancer samples. These differentially expressed genes were enriched in several pathways associated with cancer, such as metabolic pathways, pathways in cancer, and PI3K-Akt signaling pathway. Furthermore, marker genes, STAT1, ANP32E, GPRC5A, and EGFL6, were highly expressed in ovarian cancer, while PMP22, FBXO21, and CYB5R3 were lowly expressed in ovarian cancer. These marker genes were positively associated with prognosis of ovarian cancer.

Conclusion

Our findings revealed specific cell subpopulations and marker genes in ovarian cancer using single-cell RNA-seq, which provided a novel insight into the heterogeneity of ovarian cancer.

GALNT14 regulates ferroptosis and apoptosis of ovarian cancer through the EGFR/mTOR pathway

Background: Chemoresistance usually occurs in ovarian cancer. We aimed to explore the mechanisms of chemoresistance. Methods: Western blotting assay was used to detect the expression of GALNT14. Further cell function experiments were performed to investigate the effect of GALNT14 in ovarian cancer. Results: GALNT14 is significantly upregulated in ovarian cancer. Downregulation of GALNT14 significantly inhibits both apoptosis and ferroptosis of ovarian cancer cells. A further mechanism assay illustrated that downregulation of GALNT14 suppresses the activity of the mTOR pathway through modifying O-glycosylation of EGFR. Finally, an additive effect promoting cell death occurs with a combination of an mTOR inhibitor and cisplatin. Conclusion: Our study might provide a promising method to overcome cisplatin resistance for patients with ovarian cancer.

FBP1 regulates proliferation, metastasis, and chemoresistance by participating in C-MYC/STAT3 signaling axis in ovarian cancer

Fructose-1,6-bisphosphatase (FBP1) is a rate-limiting enzyme in gluconeogenesis and an important tumor suppressor in human malignancies. Here, we aimed to investigate the expression profile of FBP1 in ovarian cancer, the molecular mechanisms that regulate FBP1 expression and to examine how the FBP1 regulatory axis contributes to tumorigenesis and progression in ovarian cancer. We showed that FBP1 expression was significantly decreased in ovarian cancer tissues compared with normal ovarian tissues, and low-FBP1 expression predicted poor prognosis in patients with ovarian cancer. The enhanced expression of FBP1 in ovarian cancer cell lines suppressed proliferation and 2-D/3-D invasion, reduced aerobic glycolysis, and sensitized cancer cells to cisplatin-induced apoptosis. Moreover, DNA methylation and C-MYC binding at the promoter inhibited FBP1 expression. Furthermore, through physical interactions with signal transducer and activator of transcription 3 (STAT3), FBP1 suppressed nuclear translocation of STAT3 and exerted its non-metabolic enzymatic activity to induce the dysfunction of STAT3. Thus, our study suggests that FBP1 may be a valuable prognostic predictor for ovarian cancer. C-MYC-dependent downregulation of FBP1 acted as a tumor suppressor via modulating STAT3, and the C-MYC/FBP1/STAT3 axis could be a therapeutic target.

Mechanisms and Advances in Anti-Ovarian Cancer with Natural Plants Component

Ovarian cancer ranks seventh in the most common malignant tumors among female disease, which seriously threatens female reproductive health. It is characterized by hidden pathogenesis, missed diagnosis, high reoccurrence rate, and poor prognosis. In clinic, the first-line treatment prioritized debulking surgery with paclitaxel-based chemotherapy. The harsh truth is that female patients are prone to relapse due to the dissemination of tumor cells and drug resistance. In these circumstances, the development of new therapy strategies combined with traditional approaches is conductive to improving the quality of treatment. Among numerous drug resources, botanical compounds have unique advantages due to their potentials in multitarget functions, long application history, and wide availability. Previous studies have revealed the therapeutic effects of bioactive plant components in ovarian cancer. These natural ingredients act as part of the initial treatment or an auxiliary option for maintenance therapy, further reducing the tumor and metastatic burden. In this review, we summarized the functions and mechanisms of natural botanical components applied in human ovarian cancer. We focused on the molecular mechanisms of cell apoptosis, autophagy, RNA and DNA lesion, ROS damage, and the multiple-drug resistance. We aim to provide a theoretical reference for in-depth drug research so as to manage ovarian cancer better in clinic.

The Mechanism of Warburg Effect-Induced Chemoresistance in Cancer

Although chemotherapy can improve the overall survival and prognosis of cancer patients, chemoresistance remains an obstacle due to the diversity, heterogeneity, and adaptability to environmental alters in clinic. To determine more possibilities for cancer therapy, recent studies have begun to explore changes in the metabolism, especially glycolysis. The Warburg effect is a hallmark of cancer that refers to the preference of cancer cells to metabolize glucose anaerobically rather than aerobically, even under normoxia, which contributes to chemoresistance. However, the association between glycolysis and chemoresistance and molecular mechanisms of glycolysis-induced chemoresistance remains unclear. This review describes the mechanism of glycolysis-induced chemoresistance from the aspects of glycolysis process, signaling pathways, tumor microenvironment, and their interactions. The understanding of how glycolysis induces chemoresistance may provide new molecular targets and concepts for cancer therapy.

Metabolic reprogramming in epithelial ovarian cancer

Cancer cells usually show adaptations to their metabolism that facilitate their growth, invasiveness, and metastasis. Therefore, reprogramming the energy metabolism is one of the current key foci of cancer research and treatment. Although aerobic glycolysis-the Warburg effect-has been thought to be the dominant energy metabolism in cancer, recent data indicate a different possibility, specifically that oxidative phosphorylation (OXPHOS) is the more likely form of energy metabolism in some cancer cells. Due to the heterogeneity of epithelial ovarian cancer, there are different metabolic preferences among cell types, study types (in vivo/in vitro), and invasiveness. Current knowledge acknowledges glycolysis to be the main energy provider in ovarian cancer growth, invasion, migration, and viability, so specific agents targeting the glycolysis or OXPHOS pathways have been used in previous studies to attenuate tumor progression and increase chemosensitization. However, chemoresistant cell lines exert various metabolic preferences. This review comprehensively summarizes the information from existing reports which could together provide an in-depth understanding and insights for the development of a novel targeted therapy which can be used as an adjunctive treatment to standard chemotherapy to decelerate tumor progression and decrease the epithelial ovarian cancer mortality rate.

Overexpression of E74-like transformation-specific transcription factor 3 promotes cellular proliferation and predicts poor prognosis in ovarian cancer

E74-like E26 transformation-specific (ETS) transcription factor 3 (ELF3), is a member of the ETS transcription factor family, and has been characterized as an epithelial cell-specific transcription factor. The role of ELF3 in tumor progression remains to be elucidated. Previous studies have indicated that loss of ELF3 mRNA and protein expression was associated with poor outcomes in ovarian cancer (OC). By contrast, the present study demonstrated that ELF3 was upregulated in OC, using data from The Cancer Genome Atlas, and elevated expression levels of ELF3 were associated with a poor prognosis. ELF3 promoted OC cell proliferation in vitro and in vivo. The present study revealed that ELF3 inhibited apoptosis and reduced the cisplatin sensitivity of OC cells. Furthermore, the mTOR pathway was found to be activated by ELF3. Collectively, the results of the present study indicated the role of ELF3 in the development and pathogenesis of OC.

Ultra-Small Platinum Nanoparticle-Enabled Catalysis and Corrosion Susceptibility Reverse Tumor Hypoxia for Cancer Chemoimmunotherapy

A major challenge in the use of chemotherapy and immunotherapy is hypoxia-induced progression of tumor cells. We aim to curb hypoxia using metal-based O₂-producing nanomedicine. The key focus is therapeutic targeting of hypoxia-inducible factor 1α (HIF-1α), a major reactive oxygen species (ROS)-activated player that drives hypoxia-dependent tumor progression. Inhibition of tumor growth by blocking both HIF-1α and immune checkpoint molecules via ROS removal is a promising new strategy to avoid ROS-induced hypoxia signaling and boost antitumor immunity. Here, we investigated the synergistic effect of ultra-small platinum nanoparticles (Pt-nano) with dual functions of enzyme-mimicking catalysis and corrosion susceptibility to block hypoxia signaling of tumors. Ultra-small Pt-nano with highly corrosive susceptibility can efficiently catalyze ROS scavenging and promote oxygen accumulation for hypoxia reversal, leading to reduced HIF-1α expression. The unique corrosion susceptibility allows ultra-small Pt-nano to effectively exert platinum cytotoxicity, induce reversal of hypoxia-mediated immune suppression by promoting cytotoxic T-cell infiltration of tumors, and reduce the levels of tumoral immune checkpoint molecules and immunosuppressive cytokines. In combination with immune checkpoint blockade using monoclonal antibodies, nanoparticle-enabled enzyme-mimicking is a promising strategy for the enhancement of chemoimmunotherapeutic efficacy through the reversal of tumor hypoxia.

SOHLH2 Suppresses Angiogenesis by Downregulating HIF1α Expression in Breast Cancer

SOHLH2 has been demonstrated the downregulation in various cancers and the involvement in tumor growth and metastasis. However, the function of SOHLH2 on tumor angiogenesis and the underlying molecular mechanisms have not been interrogated. IHC staining results revealed that SOHLH2 was negatively associated with microvessel density (MVD), tumor size, histology grade, and metastasis. Overexpression of SOHLH2 inhibited the angiogenic behavior of human umbilical vein endothelial cells (HUVEC) by a tumor cell-mediated paracrine signal, while knockdown of SOHLH2 promoted HUVEC angiogenic behavior. Ectopic SOHLH2 expression remarkably suppressed tumor growth and MVD in xenograft tumors, downregulated the expression of hypoxia inducible factor-1 alpha (HIF1α)-mediated proangiogenic genes in vivo and in vitro, while knockdown of SOHLH2 had an opposite result. Furthermore, we found that upregulation of HIF1α reversed SOHLH2-induced suppression of breast cancer angiogenesis, while KC7F2, the inhibitor of HIF1α, could attenuate the promotion of angiogenesis by SOHLH2 silencing. Using Chromatin immunoprecipitation and luciferase reporter assays, we validated that SOHLH2 could directly bind to HIF1α promoter and repress its transcriptional activity. Collectively, SOHLH2 suppresses breast cancer angiogenesis by downregulating HIF1α transcription and may be a potential biomarker for anti-angiogenesis therapy. IMPLICATIONS: SOHLH2 directly represses HIF1α-mediated angiogenesis and serves as an important inhibitor of angiogenesis in breast cancer.

Cisplatin and paclitaxel co-delivery nanosystem for ovarian cancer chemotherapy

We have designed and developed an effective drug delivery system using biocompatible polymer of poly (ethylene glycol)-polyaspartic acid (mPEG-PAsp) for co-loading the chemotherapy drugs paclitaxel (PTX) and cisplatin (CP) in one nano-vehicle. This study aimed to improve the anti-cancer efficacy of combinations of chemotherapy drugs and reduce their side effects. mPEG-PAsp-(PTX/Pt) nano-micelles disperse well in aqueous solution and have a narrow size distribution (37.8 ± 3.2 nm) in dynamic light scattering (DLS). Drug release profiles found that CP released at pH 5.5 was significantly faster than that at pH 7.4. MPEG-PAsp-(PTX/Pt) nano-micelles displayed a significantly higher tumor inhibitory effect than mPEG-PAsp-PTX nano-micelles when the polymer concentrations reached 50 μg/mL. Our data indicated that polymer micelles of mPEG-PAsp loaded with the combined drug exert synergistic anti-tumor efficacy on SKOV3 ovarian cells via different action mechanisms. Results from our studies suggested that mPEG-PAsp-(PTX/Pt) nano-micelles are promising alternatives for carrying and improving the delivery of therapeutic drugs with different water solubilities.

α-Tomatine, a novel early-stage autophagy inhibitor, inhibits autophagy to enhance apoptosis via Beclin-1 in Skov3 cells

Targeting the autophagy process is considered to be a promising new strategy for drug treatment of ovarian cancer. α-Tomatine, a steroidal alkaloid extracted, is mainly isolated from leaves, roots and immature green tomatoes. α-Tomatine has biological activities such as anticancer, antioxidative and anti-inflammatory. The study aimed to explore the effects of α-tomatine on proliferation, apoptosis and autophagy and the underlying mechanisms in ovarian cancer Skov3 cells. After treatment with different concentrations of α-tomatine (0, 0.75, 1 and 1.5 μM) in Skov3 cells for 24 h, proliferation was determined by the CCK-8 assay, and apoptosis was detected by flow cytometric analysis. Autophagy in cells was determined by the number of fluorescent spots using confocal fluorescence microscopy after mRFP-GFP-LC3 transfection. The relationship between autophagy and apoptosis was proved by Beclin-1 overexpression. The protein expression levels were tested by western blotting. The results demonstrated that α-tomatine effectively repressed proliferation, exerted a proapoptotic effect and inhibited early-stage autophagy in Skov3 cells in a dose- and time-dependent manner. Additionally, Beclin-1 overexpression significantly suppressed α-tomatine-treated apoptosis in Skov3 cells, indicating that α-tomatine inhibits autophagy to induce apoptosis. We also found α-tomatine inhibited the protein expression levels of PI3K/Akt/mTOR signaling pathway. However, the autophagy inhibition of α-tomatine could be reversed obviously by Beclin-1 overexpression. Taken together, α-tomatine inhibited autophagy through Beclin-1. Our study suggests that α-tomatine, as a novel early-stage autophagy inhibitor, might be a potential drug for further treatment of ovarian cancer by inhibiting proliferation and promoting apoptosis.

Theasaponin E1 Inhibits Platinum-Resistant Ovarian Cancer Cells through Activating Apoptosis and Suppressing Angiogenesis

Novel therapeutic strategies for ovarian cancer treatment are in critical need due to the chemoresistance and adverse side effects of platinum-based chemotherapy. Theasaponin E₁ (TSE1) is an oleanane-type saponin from Camellia sinensis seeds. Its apoptosis-inducing, cell cycle arresting and antiangiogenesis activities against platinum-resistant ovarian cancer cells were elucidated in vitro and using the chicken chorioallantoic membrane (CAM) assay. The results showed that TSE1 had more potent cell growth inhibitory effects on ovarian cancer OVCAR-3 and A2780/CP70 cells than cisplatin and was lower in cytotoxicity to normal ovarian IOSE-364 cells. TSE1 significantly induced OVCAR-3 cell apoptosis via the intrinsic and extrinsic apoptotic pathways, slightly arresting cell cycle at the G2/M phase, and obviously inhibited OVCAR-3 cell migration and angiogenesis with reducing the protein secretion and expression of vascular endothelial growth factor (VEGF). Western bolt assay showed that Serine/threonine Kinase (Akt) signaling related proteins including Ataxia telangiectasia mutated kinase (ATM), Phosphatase and tensin homolog (PTEN), Akt, Mammalian target of rapamycin (mTOR), Ribosome S6 protein kinase (p70S6K) and e IF4E-binding protein 1(4E-BP1) were regulated, and Hypoxia inducible factor-1α (HIF-1α) protein expression was decreased by TSE1 in OVCAR-3 cells. Moreover, TSE1 treatment potently downregulated protein expression of the Notch ligands including Delta-like protein 4 (Dll4) and Jagged1, and reduced the protein level of the intracellular domain (NICD) of Notch1. Combination treatment of TSE1 with the Notch1 signaling inhibitor tert-butyl (2S)-2-[[(2S)-2-[[2-(3,5-difluorophenyl)acetyl]amino]propanoyl]amino]-2-phenylacetate (DAPT), or the Akt signaling inhibitor wortmannin, showed a stronger inhibition toward HIF-1α activation compared with single compound treatment. Taken together, TSE1 might be a potential candidate compound for improving platinum-resistant ovarian cancer treatment via Dll4/Jagged1-Notch1-Akt-HIF-1α axis.

Exploiting the acquired vulnerability of cisplatin-resistant tumors with a hypoxia-amplifying DNA repair-inhibiting (HYDRI) nanomedicine

Various cancers treated with cisplatin almost invariably develop drug resistance that is frequently caused by substantial DNA repair. We searched for acquired vulnerabilities of cisplatin-resistant cancers to identify undiscovered therapy. We herein found that cisplatin resistance of cancer cells comes at a fitness cost of increased intracellular hypoxia. Then, we conceived an inspired strategy to combat the tumor drug resistance by exploiting the increased intracellular hypoxia that occurs as the cells develop drug resistance. Here, we constructed a hypoxia-amplifying DNA repair-inhibiting liposomal nanomedicine (denoted as HYDRI NM), which is formulated from a platinum(IV) prodrug as a building block and payloads of glucose oxidase (GOx) and hypoxia-activatable tirapazamine (TPZ). In studies on clinically relevant models, including patient-derived organoids and patient-derived xenograft tumors, the HYDRI NM is able to effectively suppress the growth of cisplatin-resistant tumors. Thus, this study provides clinical proof of concept for the therapy identified here.

Overexpression of miR-329-3p sensitizes osteosarcoma cells to cisplatin through suppression of glucose metabolism by targeting LDHA

Osteosarcoma (OS) is one of the most frequent malignant bone tumor types. Traditional treatments of OS involve standard chemotherapy or combination with radiation before and after surgery. Cisplatin is one of the most effective chemotherapeutic drugs used for treating osteosarcoma. However, patients with advanced tumor stages develop cisplatin resistance, leading to a major clinical challenge. In this study, we investigated the roles of miR-329-3p in cisplatin sensitivity of osteosarcoma cells. We found miR-329-3p was significantly downregulated in osteosarcoma tissues compared with normal bone tissues. Overexpression of miR-329-3p suppressed osteosarcoma cell proliferation. Moreover, we observed low-toxic cisplatin treatments suppressed miR-329-3p but higher concentrations of cisplatin-induced miR-329-3p expression. In addition, miR-329-3p was significantly downregulated in cisplatin-resistant Saos-2 cells which displayed elevated glucose metabolism. Overexpression of miR-329-3p significantly impaired glucose metabolism of Saos-2 cells. Bioinformatics analysis and luciferase assay consistently demonstrated the glycolysis enzyme, lactate dehydrogenase-A (LDHA) was a direct target of miR-329-3p in osteosarcoma cells. Rescue experiments revealed restoration of LDHA in miR-329-3p-overexpressed cisplatin-resistant cells effectively recovered glucose metabolism, resulting in increased cisplatin resistance. This study demonstrates a miR-329-3p-LDHA-glucose metabolism-cisplatin resistance axis in osteosarcoma cells, providing a miRNA-based therapeutic strategy against chemoresistant osteosarcoma.

LncRNA-SARCC sensitizes osteosarcoma to cisplatin through the miR-143-mediated glycolysis inhibition by targeting Hexokinase 2

Chemotherapy is one of the primary treatments used against cancer. Cisplatin is a conventional chemotherapy drug used to treat osteosarcoma; however, due to the development of cisplatin resistance, advantageous therapeutic outcomes and prognosis of osteosarcoma remain low. Thus, investigation of the specific targeted therapies to circumvent the anti-chemoresistance of osteosarcoma depends on understanding the molecular mechanisms underlying cisplatin resistance. Tumor cells display an increased utilization of glycolysis rather than oxidative phosphorylation. This phenomenon is called the "Warburg effect," which presents a survival advantage for tumor cells, leading to chemoresistance. To date, the molecular mechanism underlying osteosarcoma cisplatin resistance remains to be fully elucidated. In this study, we reported the significant down-regulation of the long noncoding RNA-Suppressing Androgen Receptor in Renal Cell Carcinoma (lncRNA-SARCC) in the cells of osteosarcoma and in the specimens from osteosarcoma patients. Moreover, we observed a negative correlation between the lncRNA-SARCC and cisplatin resistance in the osteosarcoma tissues. Overexpression of the lncRNA-SARCC sensitizes osteosarcoma cells to cisplatin. From microarray analysis, we screened several miRNAs, which are significantly regulated by the lncRNA-SARCC in osteosarcoma cells, and revealed that lncRNA-SARCC promoted microRNA-43 (miR-143) expression in osteosarcoma. Interestingly, miR-143 showed the same expression pattern with the lncRNA-SARCC in osteosarcoma patient specimens. By establishing a cisplatin-resistant cell line from Sarcoma Osteogenic-2 (Saos-2), we found the cisplatin-resistant cells with down-regulated expressions of the lncRNA-SARCC and miR-143, but with a higher glycolysis rate compared to that in parental cells. We identified the glycolysis key enzyme, Hexokinase 2 (HK2), as a direct target for miR-143 in osteosarcoma. Restoration of the HK2 expression in the lncRNA-SARCC-overexpressing osteosarcoma cells reversed cisplatin resistance, suggesting that lncRNA-SARCC-mediated cisplatin sensitivity may be via glycolysis in the miR-143-inhibited osteosarcoma cells. Finally, results from both in vitro and in vivo xenograft models demonstrated that the lncRNA-SARCC was an effective therapeutic agent for overcoming cisplatin resistance in osteosarcoma. Our findings suggest an essential axis of the lncRNA-SARCC-miR-143-HK2 in regulation of osteosarcoma chemosensitivity, presenting the lncRNA-SARCC as a new therapeutic target against cisplatin-resistant osteosarcoma.

HIF in Nephrotoxicity during Cisplatin Chemotherapy: Regulation, Function and Therapeutic Potential

Simple Summary

Cisplatin is a widely used chemotherapy drug, but its use and efficacy are limited by its nephrotoxicity. HIF has protective effects against kidney injury during cisplatin chemotherapy, but it may attenuate the anti-cancer effect of cisplatin. In this review, we describe the role and regulation of HIF in cisplatin-induced nephrotoxicity and highlight the therapeutic potential of targeting HIF in chemotherapy.

Abstract

Cisplatin is a highly effective, broad-spectrum chemotherapeutic drug, yet its clinical use and efficacy are limited by its side effects. Particularly, cancer patients receiving cisplatin chemotherapy have high incidence of kidney problems. Hypoxia-inducible factor (HIF) is the “master” transcription factor that is induced under hypoxia to trans-activate various genes for adaptation to the low oxygen condition. Numerous studies have reported that HIF activation protects against AKI and promotes kidney recovery in experimental models of cisplatin-induced acute kidney injury (AKI). In contrast, little is known about the effects of HIF on chronic kidney problems following cisplatin chemotherapy. Prolyl hydroxylase (PHD) inhibitors are potent HIF inducers that recently entered clinical use. By inducing HIF, PHD inhibitors may protect kidneys during cisplatin chemotherapy. However, HIF activation by PHD inhibitors may reduce the anti-cancer effect of cisplatin in tumors. Future studies should test PHD inhibitors in tumor-bearing animal models to verify their effects in kidneys and tumors.

Identification of Hypoxia Signature to Assess the Tumor Immune Microenvironment and Predict Prognosis in Patients with Ovarian Cancer

BACKGROUND

The 5-year overall survival rate of ovarian cancer (OC) patients is less than 40%. Hypoxia promotes the proliferation of OC cells and leads to the decline of cell immunity. It is crucial to find potential predictors or risk model related to OC prognosis. This study aimed at establishing the hypoxia-associated gene signature to assess tumor immune microenvironment and predicting the prognosis of OC.

METHODS

The gene expression data of 378 OC patients and 370 OC patients were downloaded from datasets. The hypoxia risk model was constructed to reflect the immune microenvironment in OC and predict prognosis.

RESULTS

8 genes (AKAP12, ALDOC, ANGPTL4, CITED2, ISG20, PPP1R15A, PRDX5, and TGFBI) were included in the hypoxic gene signature. Patients in the high hypoxia risk group showed worse survival. Hypoxia signature significantly related to clinical features and may serve as an independent prognostic factor for OC patients. 2 types of immune cells, plasmacytoid dendritic cell and regulatory T cell, showed a significant infiltration in the tissues of the high hypoxia risk group patients. Most of the immunosuppressive genes (such as ARG1, CD160, CD244, CXCL12, DNMT1, and HAVCR1) and immune checkpoints (such as CD80, CTLA4, and CD274) were upregulated in the high hypoxia risk group. Gene sets related to the high hypoxia risk group were associated with signaling pathways of cell cycle, MAPK, mTOR, PI3K-Akt, VEGF, and AMPK.

CONCLUSION

The hypoxia risk model could serve as an independent prognostic indicator and reflect overall immune response intensity in the OC microenvironment.

A highly annotated database of genes associated with platinum resistance in cancer

Platinum-based chemotherapy, including cisplatin, carboplatin, and oxaliplatin, is prescribed to 10-20% of all cancer patients. Unfortunately, platinum resistance develops in a significant number of patients and is a determinant of clinical outcome. Extensive research has been conducted to understand and overcome platinum resistance, and mechanisms of resistance can be categorized into several broad biological processes, including (1) regulation of drug entry, exit, accumulation, sequestration, and detoxification, (2) enhanced repair and tolerance of platinum-induced DNA damage, (3) alterations in cell survival pathways, (4) alterations in pleiotropic processes and pathways, and (5) changes in the tumor microenvironment. As a resource to the cancer research community, we provide a comprehensive overview accompanied by a manually curated database of the >900 genes/proteins that have been associated with platinum resistance over the last 30 years of literature. The database is annotated with possible pathways through which the curated genes are related to platinum resistance, types of evidence, and hyperlinks to literature sources. The searchable, downloadable database is available online at http://ptrc-ddr.cptac-data-view.org .

Hypoxia-Mediated Decrease of Ovarian Cancer Cells Reaction to Treatment: Significance for Chemo- and Immunotherapies

Hypoxia, a common factor ruling the microenvironment composition, leads to tumor progression. In this hypoxic context, cytokines and cells cooperate to favor cancer development and metastasis. Tumor hypoxia is heterogeneously distributed. Oxygen gradients depend on the vicinity, functionality of blood vessels, and oxygen ability to diffuse into surrounding tissues. Thus, the vasculature state modulates the microenvironment of the tumor cells. Cells sense and react to small variations in oxygen tension, which explains the lack of tumor cells’ unicity in their reaction to drugs. Ovarian cancers are highly hypoxia-dependent, ascites worsening the access to oxygen, in their reactions to both chemotherapy and new immunotherapy. Consequently, hypoxia affects the results of immunotherapy, and is thus, crucial for the design of treatments. Controlling key immunosuppressive factors and receptors, as well as immune checkpoint molecule expression on tumor, immune and stromal cells, hypoxia induces immunosuppression. Consequently, new approaches to alleviate hypoxia in the tumor microenvironment bring promises for ovarian cancer immunotherapeutic strategies. This review focuses on the effects of hypoxia in the microenvironment and its consequences on tumor treatments. This opens the way to innovative combined treatments to the advantage of immunotherapy outcome in ovarian cancers.

The regulation of bcr-abl in hypoxia is through the mTOR pathway

Chronic myeloid leukemia (CML) is usually characterized by the formation of the fusion onco-protein bcr-abl. Therefore, the majority of CML treatments are bcr-abl specific tyrosine kinase inhibitors (TKIs). TKI resistance in CML treatment is becoming a major obstacle in managing this disease. One well-studied form of drug resistance is hypoxia-induced drug resistance, a phenomenon observed in many other cancers. This study aimed to determine the efficacy of TKIs in CML cells cultured in hypoxia. It was observed that bcr-abl translation was severely halted in hypoxia, rendering TKIs ineffective. We found that the mechanism by which bcr-abl protein levels were being suppressed in hypoxia was through the mTOR pathway, specifically via ribosomal protein S6 (RPS6). This information is vital to the improvement of CML treatments, as it can be used to determine how to best combat hypoxia-induced drug resistance in CML and subsequently to identify new targets for treatment.

PGC1α regulates mitochondrial oxidative phosphorylation involved in cisplatin resistance in ovarian cancer cells via nucleo-mitochondrial transcriptional feedback

Mitochondria play an important role in effective cell energy production and cell survival under stress conditions, such as treatment with chemotherapeutic drugs. Mitochondrial biogenesis is increased in ovarian cancer tissues, which is accompanied by alteration of mitochondrial energy metabolism, structure, and dynamics. These factors are involved in tumorigenesis and apoptosis resistance, highlighting the role of mitochondria in resisting cisplatin toxicity. Cisplatin-resistant ovarian cancer cells are dependent on mitochondrial OXPHOS for energy supply, and intracellular PGC1α-mediated mitochondrial biogenesis levels are increased in this cell line, indicating the important role of mitochondrial oxidative phosphorylation in cisplatin resistance. As PGC1α is a key molecule for integrating and coordinating nuclear DNA and mitochondrial DNA transcriptional machinery, an investigation into the regulatory mechanism PGC1α in mitochondrial energy metabolism via transcription may provide new clues for solving chemotherapy resistance. In the present study, it was demonstrated that inhibiting the expression of PGC1α decreased nuclear and mitochondrial DNA transcription factor expression, leading to increased lactic acid production and decreased cellular oxygen consumption and mitochondrial oxidative phosphorylation. Furthermore, mitochondrial stress-induced ROS production, as a feedback signal from mitochondria to the cell nucleus, increased PGC1α expression in SKOV3/DDP cells, which was involved in mitochondrial oxidative phosphorylation regulation. Collectively, the present study provides evidence that PGC1α-mediated nuclear and mitochondrial transcription feedback regulates energy metabolism and is involved in ovarian cancer cells escaping apoptosis during cisplatin treatment.

CircPVT1 Promoted the Progression of Breast Cancer by Regulating MiR-29a-3p-Mediated AGR2-HIF-1α Pathway

Background

Breast cancer (BC) is a great contributor to cancer-related death. Mounting studies have identified that circular RNAs (circRNAs) play vital roles in cancer cell proliferation, apoptosis and invasion. Here, we explored the effect of circPVT1 on BC development as well as its downstream mechanisms.

Methods

qRT-PCR was used to determine the relative expression levels of circPVT1 and miR-29a-3p in BC tissue samples and cell lines. We also analyzed the relevance between pathological indexes and circPVT1 expression level. Human breast cancer cell lines MCF-7 and MDA-MB-231 were taken as cell models. Gain- or loss-of-functional assays of circPVT1 and miR-29a-3p were conducted in BC cell lines to investigate their effects on the cell proliferation, apoptosis, migration and invasion. The protein levels of AGR2, HIF-1α, Bax, Bcl2 and Caspase3 were determined by Western blot. Furthermore, dual-luciferase reporter assay and RNA fluorescence in situ hybridization (FISH) were used to confirm the targeted relationships between circPVT1 and miR-29a-3p, miR-29a-3p and anterior gradient 2 (AGR2).

Results

CircPVT1 was highly expressed while miR-29a-3p was lowly expressed in BC tissues and cell lines. Inhibition of circPVT1 or overexpression of miR-29a-3p remarkably suppressed BC cell proliferation, invasion and migration while promoted cell apoptosis. By contrast, circPVT1 upregulation or miR-29a-3p inhibition led to mitigate malignant behaviours of BC cells. Functionally, circPVT1 bound to miR-29a-3p, and AGR2 was a target gene of miR-29a-3p. Overexpressed circPVT1 promoted AGR2 and HIF-1α expression by repressing miR-29a-3p. More importantly, overexpressing AGR2 enhances HIF-1α expression, accompanied with accelerated proliferation, invasion and migration of BC cells.

Conclusion

CircPVT1 acts as an oncogene in BC via promoting the growth, invasion, migration and inhibiting apoptosis through miR-29a-3p-mediated AGR2-HIF-1α axis.

Minocycline in Treating Glioblastoma Multiforme: Far beyond a Conventional Antibiotic

One of the most lethal forms of CNS pathologies is glioblastoma multiforme (GBM) that represents high invasiveness, uncontrolled proliferation, and angiogenic features. Its invasiveness is responsible for the high recurrence even after maximal surgical interventions. Minocycline is a semisynthetic analog of tetracyclines with potential anti-inflammatory and anticancer effects, distinct from its antimicrobial activity. In this review, we highlight the importance and the cytotoxic mechanisms of minocycline on GBM pathophysiology. Considering the role of certain enzymes in autophagy, apoptosis, tumor cell invasion, and metastatic ability, the possible use of tetracyclines for cancer therapy should be investigated, especially GBM. The present study is, therefore, going to cover the main topics in minocycline pharmacology to date, encouraging its consideration as a new treatment approach for cancer and GBM.

MicroRNA-302 represses epithelial-mesenchymal transition and cisplatin resistance by regulating ATAD2 in ovarian carcinoma

Epithelial-mesenchymal transition (EMT) is an important contributor to drug resistance in ovarian cancer. The aims of this study were to explore the potential role of the miR-302 cluster in modulating EMT and cisplatin resistance in ovarian cancer. We used qRT-PCR and western blotting to show that miR-302 expression was lower in chemoresistant than in chemosensitive cells, and miR-302 was upregulated in chemosensitive, but not chemoresistant ovarian cancer cells in response to cisplatin treatment. We identified ATAD2 as a target of miR-302 and showed that ectopic expression of miR-302 increased cisplatin sensitivity and inhibited EMT and the invasiveness of cisplatin-resistant cells in vitro by targeting ATAD2. Knockdown of ATAD2 restored cisplatin sensitivity and reversed EMT/metastasis in cisplatin-resistant cells, as shown by western blotting and invasion/migration assays. The effect of miR-302 overexpression on EMT and invasiveness was mediated by the modulation of β-catenin nuclear expression. Immunofluorescence analysis showed that ATAD2 overexpression reversed the miR-302-induced downregulation of nuclear β-catenin in cisplatin resistant cells. A xenograft tumor model was used to show that miR-302 increases the antitumor effect of cisplatin in vivo. Taken together, these results identify a potential regulatory axis involving miR-302 and ATAD2 with a role in chemoresistance, indicating that activation of miR-302 or inactivation of ATAD2 could serve as a novel approach to reverse cisplatin resistance in ovarian cancer.

Cisplatin inhibits SIRT3-deacetylation MTHFD2 to disturb cellular redox balance in colorectal cancer cell

The folate-coupled metabolic enzyme MTHFD2 (the mitochondrial methylenetetrahydrofolate dehydrogenase/cyclohydrolase) confers redox homeostasis and drives cancer cell proliferation and migration. Here, we show that MTHFD2 is hyperacetylated and lysine 88 is the critical acetylated site. SIRT3, the major deacetylase in mitochondria, is responsible for MTHFD2 deacetylation. Interestingly, chemotherapeutic agent cisplatin inhibits expression of SIRT3 to induce acetylation of MTHFD2 in colorectal cancer cells. Cisplatin-induced acetylated K88 MTHFD2 is sufficient to inhibit its enzymatic activity and downregulate NADPH levels in colorectal cancer cells. Ac-K88-MTHFD2 is significantly decreased in human colorectal cancer samples and is inversely correlated with the upregulated expression of SIRT3. Our findings reveal an unknown regulation axis of cisplatin-SIRT3-MTHFD2 in redox homeostasis and suggest a potential therapeutic strategy for cancer treatments by targeting MTHFD2.

Long-Noncoding RNA (lncRNA) in the Regulation of Hypoxia-Inducible Factor (HIF) in Cancer

Hypoxia is dangerous for oxygen-dependent cells, therefore, physiological adaption to cellular hypoxic conditions is essential. The transcription factor hypoxia-inducible factor (HIF) is the main regulator of hypoxic metabolic adaption reducing oxygen consumption and is regulated by gradual von Hippel-Lindau (VHL)-dependent proteasomal degradation. Beyond physiology, hypoxia is frequently encountered within solid tumors and first drugs are in clinical trials to tackle this pathway in cancer. Besides hypoxia, cancer cells may promote HIF expression under normoxic conditions by altering various upstream regulators, cumulating in HIF upregulation and enhanced glycolysis and angiogenesis, altogether promoting tumor proliferation and progression. Therefore, understanding the underlying molecular mechanisms is crucial to discover potential future therapeutic targets to evolve cancer therapy. Long non-coding RNAs (lncRNA) are a class of non-protein coding RNA molecules with a length of over 200 nucleotides. They participate in cancer development and progression and might act as either oncogenic or tumor suppressive factors. Additionally, a growing body of evidence supports the role of lncRNAs in the hypoxic and normoxic regulation of HIF and its subunits HIF-1α and HIF-2α in cancer. This review provides a comprehensive update and overview of lncRNAs as regulators of HIFs expression and activation and discusses and highlights potential involved pathways.

miR-454 suppresses the proliferation and invasion of ovarian cancer by targeting E2F6

Background

The aberrant expression of microRNA-454 (miR-454) has been confirmed to be involved in the development of cancers. However, the functional role of miR-454 in the progression of ovarian cancer remains unclear.

Methods

The expression of miR-454 in ovarian cancer cells and serum of ovarian cancer patients was detected by RT-PCR. CCK8, colony formation, transwell, and flow cytometry assays were conducted to assess the effects of miR-454 on ovarian cancer cell proliferation, migration, invasion, and apoptosis, respectively. Dual-luciferase reporter assay was used to confirm the targeting relationship between miR-454 and E2F6. The expression pattern of E2F6 in ovarian cancer tissues was detected using immunohistochemistry (IHC) assay. The relative expression of related proteins was examined using western blot analysis.

Results

miR-454 was markedly down-regulated by hypoxia in ovarian cancer cells. Compared with normal samples, the expression of miR-454 was up-regulated in the serum of ovarian cancer patients, and correlated with the clinicopathological stages of ovarian cancer. Next, we found that miR-454 overexpression inhibited the proliferation, migration and invasion of OVCAR3 and SKOV3 cells, as well as promoted apoptosis. In addition, the Akt/mTOR and Wnt/β-catenin signaling pathway were inhibited by miR-454 in ovarian cancer cells. Mechanically, bioinformatic analysis and dual-luciferase reporter assay confirmed that E2F6 was a direct target of miR-454 and negatively regulated by miR-454 in ovarian cancer cells. Moreover, IHC analysis showed that E2F6 was highly expressed in ovarian cancer tissues. Finally, we found that the increasing cell proliferation and migration triggered by E2F6 overexpression were abolished by miR-454 overexpression.

Conclusion

Taken together, these results highlight the role of miR-454 as a tumor suppressor in ovarian cancer cells by targeting E2F6, indicating that miR-454 may be a potential diagnostic biomarker and therapeutic target for ovarian cancer.

Mitochondrial APE1 promotes cisplatin resistance by downregulating ROS in osteosarcoma

Apurinic/apyrimidinic endonuclease 1 (APE1) is a primary nuclear-localized multifunctional protein in osteosarcoma. However, the cytoplasmic localization of APE1 was found to be functional and to increase with cisplatin resistance, yet the molecular mechanism is unknown. In the present study, we explored the cisplatin resistance mechanism in osteosarcoma from the new perspective of APE1 extranuclear biological activity. Using cisplatin-resistant and cisplatin-sensitive osteosarcoma cell lines, we found that mitochondrial APE1 (mtAPE1) was overexpressed in cisplatin-resistant cells but not in sensitive cells. Overexpression of mtAPE1 reduced cisplatin-induced apoptosis, while knockdown of APE1 reversed this phenomenon and caused oxidative DNA damage via overproduction of reactive oxygen species (ROS). We further demonstrated that high mtAPE1 expression could downregulate ROS production by decreasing the phosphorylation of Rac1 (p-Rac1), further promoting cisplatin resistance in osteosarcoma. Our findings suggest that mitochondrial APE1 promotes cisplatin resistance by decreasing ROS generation, which may provide new ideas for researching the molecular mechanism of osteosarcoma chemoresistance and strategies to overcome cisplatin resistance in osteosarcoma.

Leptin decreases BC cell susceptibility to NK lysis via PGC1A pathway

Large prospective studies established a link between obesity and breast cancer (BC) development. Yet, the mechanisms underlying this association are not fully understood. Among the diverse adipocytokine secreted by hypertrophic adipose tissue, leptin is emerging as a key candidate molecule linking obesity and cancer, since it promotes proliferation and invasiveness of tumors. However, the potential implication of leptin on tumor escape mechanisms remains unknown. This study aims to explore the effect of leptin on tumor resistance to NK lysis and the underlying mechanism. We found that leptin promotes both BC resistance to NK92-mediated lysis and β oxidation on MCF-7, by the up-regulation of a master regulator of mitochondrial biogenesis, the peroxisome proliferator activated receptor coactivator-1 α (PGC1A). Using adenoviral approaches, we show that acute elevation of PGC1A enhances the fatty acid oxidation pathway and decreases the susceptibility of BC cells to NK92-mediated lysis. Importantly, we identified the involvement of PGC1A and leptin in the regulation of hypoxia inducible factor-1 alpha (HIF1A) expression by tumor cells. We further demonstrate that basal BC cells MDA-MB-231 and BT-20 exhibit an increased PGC1A mRNA level and an enhanced oxidative phosphorylation activity; in comparison with luminal BC cells MCF7 and MDA-361, which are associated with more resistance NK92 lysis. Altogether, our results demonstrate for the first time how leptin could promote tumor resistance to immune attacks. Reagents blocking leptin or PGC1A activity might aid in developing new therapeutic strategies to limit tumor development in obese BC patients.

Functional genetic variants of RUVBL1 predict overall survival of Chinese patients with epithelial ovarian cancer

To date, the 5-year overall survival of epithelial ovarian cancer (EOC) remains poor. Because studies suggest that RUVBL1 may be a chemotherapeutic target for the treatment of cancer, in this study, therefore, we investigated the role of potentially functional single nucleotide polymorphisms (SNPs) of RUVBL1 in the survival of Chinese patients with EOC, and we subsequently performed functional prediction and validation of the identified significant SNPs. We found that RUVBL1 rs1057156 A>G and RUVBL1 rs149652370 A>G were associated with survival of EOC patients in the multivariate Cox proportional hazards regression analysis. Specifically, the RUVBL1 rs149652370 AG genotype was associated with a shorter progression-free survival ([adjusted hazards ratio (HR)] = 3.32, 95% confidence interval (CI) = 1.76-6.25 and P = 2.01E-04), compared with the AA genotype. The RUVBL1 rs1057156 AG (only nine had GG) genotype was also associated with a poor overall survival (adjusted HR = 1.73, 95% CI = 1.19-2.52, P = 0.004), compared with the AA genotype. Further experiments showed that the RUVBL1 rs1057156 A>G change lowered its binding affinity to microRNA-4294 and led to upregulation of the RUVBL1 expression. We further found that overexpression of RUVBL1 promoted cell proliferation and metastatic potential. Overall, RUVBL1 enhanced EOC cell proliferation, invasion and migration presumably by stimulating the process of glycolysis. Thus, this study provides evidence that functional variants of RUVBL1 may regulate its gene expression, a possible mechanism affecting survival of EOC patients and that RUVBL1 may be a potential chemotherapeutic target for the treatment of EOC patients.

Bcl2 inhibitor ABT737 reverses the Warburg effect via the Sirt3-HIF1α axis to promote oxidative stress-induced apoptosis in ovarian cancer cells

AIMS

Compared to normal cells, tumor cells maintain higher concentrations of reactive oxygen species (ROS) to support proliferation, invasion, and metastasis. Chemotherapeutic drugs often induce tumor cell apoptosis by increasing intracellular ROS concentrations to highly toxic levels. ABT737, which inhibits the apoptosis regulator B cell lymphoma 2 (Bcl2), increases the sensitivity of ovarian cancer cells to chemotherapeutic drugs by regulating the glucose metabolism, but the underlying mechanisms remain unclear. Therefore, we aimed to determine whether ABT737 promoted H₂O₂-induced tumor cell apoptosis by reversing glycolysis in ovarian cancer cells.

MAIN METHODS

SKOV3 ovarian cancer cells were treated with H₂O₂, ABT737, or both. Cell viability was compared using methyl thiazolyl tetrazolium (MTT), and flow cytometry was used to detect differences in apoptosis, ROS, and mitochondrial membrane potential. The relative expression levels of proteins associated with apoptosis and the glucose metabolism were measured using immunoblotting. Finally, glucose uptake and lactate secretion were measured using kits and compared.

KEY FINDINGS

ABT737 downregulated proteins associated with glucose uptake (GLUT1) and glycolysis (LHDA, PKM2 and HK2) via the Sirt3-HIF1α axis, reducing glucose uptake and lactate secretion in SKOV3 cells. This reversed glycolysis in the tumor cells, and promoted H₂O₂-induced apoptosis.

SIGNIFICANCE

The Bcl2 inhibitor ABT737 enhanced the anti-tumor effect of oxidative stress by reversing the Warburg effect in ovarian cancer cells, providing powerful theoretical support for further clinical applications of Bcl2 inhibitors.

Hypoxia promotes proliferation of pituitary adenomas by HIF-1α/ALKBH5 signaling in vitro

Hypoxia is a common phenomenon in pituitary adenomas (PAs). The role and mechanism of hypoxia in the PAs remains elusive. This work aimed to explore the effect of hypoxia on PAs in vitro. PA cells GT1-1 were cultured and treated under hypoxic condition. Cell proliferation assay showed the proliferation of PA cells was increased significantly by hypoxia treatment, with a peak at 12 hours. qPCR and western blot indicated that the expression of HIF-1α, ALKBH5, and Nanog were elevated by hypoxia stimuli. In conclusion, our funding demonstrated that hypoxia could increase Nanog expression through HIF-1α/ALKBH5 signaling, thereby promoting the proliferation of PA cells.

Polymorphisms in Glycolysis-Related Genes Are Associated with Clinical Outcomes of Paclitaxel-Cisplatin Chemotherapy in Non-Small Cell Lung Cancer

OBJECTIVE

This study was conducted to investigate whether polymorphisms in glycolysis-related genes are associated with clinical outcomes of patients with advanced-stage non-small cell lung cancer (NSCLC) undergoing chemotherapy.

METHODS

A total of 377 patients with NSCLC were enrolled. Sixty-five single-nucleotide polymorphisms in 26 genes involved in the glycolytic pathway were evaluated. The associations of the variants with the chemotherapy response and overall survival (OS) were analyzed.

RESULTS

Among the 65 variants investigated, PFKL rs2073436C>G and GPI rs7248411C>G significantly correlated with clinical outcomes after chemotherapy in multivariate analyses. PFKL rs2073436C>G was significantly associated with both a worse response to chemotherapy (adjusted odds ratio [aOR] = 0.64, 95% CI = 0.45-0.90, p = 0.01) and a worse OS (adjusted hazard ratio [aHR] = 1.35, 95% CI = 1.14-1.61, p = 0.001). GPI rs7248411C>G was significantly associated with both a better chemotherapy response (aOR = 1.58, 95% CI = 1.07-2.23, p = 0.02) and a better OS (aHR = 0.80, 95% CI = 0.66-0.98, p = 0.03). When stratified by tumor histology, PFKL rs2073436C>G was significantly associated with OS only in squamous cell carcinoma, whereas GPI rs7248411C>G exhibited a significant association with the chemotherapy response and OS only in adenocarcinoma.

CONCLUSION

This result suggests that the PFKL rs2073436C>G and GPI rs7248411C>G are useful for predicting the clinical outcome of first-line paclitaxel-cisplatin chemotherapy in NSCLC.

The Drug-Resistance Mechanisms of Five Platinum-Based Antitumor Agents

Platinum-based anticancer drugs, including cisplatin, carboplatin, oxaliplatin, nedaplatin, and lobaplatin, are heavily applied in chemotherapy regimens. However, the intrinsic or acquired resistance severely limit the clinical application of platinum-based treatment. The underlying mechanisms are incredibly complicated. Multiple transporters participate in the active transport of platinum-based antitumor agents, and the altered expression level, localization, or activity may severely decrease the cellular platinum accumulation. Detoxification components, which are commonly increasing in resistant tumor cells, can efficiently bind to platinum agents and prevent the formation of platinum–DNA adducts, but the adducts production is the determinant step for the cytotoxicity of platinum-based antitumor agents. Even if adequate adducts have formed, tumor cells still manage to survive through increased DNA repair processes or elevated apoptosis threshold. In addition, autophagy has a profound influence on platinum resistance. This review summarizes the critical participators of platinum resistance mechanisms mentioned above and highlights the most potential therapeutic targets or predicted markers. With a deeper understanding of the underlying resistance mechanisms, new solutions would be produced to extend the clinical application of platinum-based antitumor agents largely.

Propofol inhibits proliferation and cisplatin resistance in ovarian cancer cells through regulating the microRNA‑374a/forkhead box O1 signaling axis

Ovarian cancer is a prominent disease that demonstrates high incidence rates in women and often presents multidrug resistance. Propofol has been demonstrated to suppress the malignancy of various types of human cancer; however, the underlying molecular mechanisms of propofol in ovarian cancer remain largely unknown. The present study aimed to investigate whether and how propofol inhibits proliferation and cisplatin (DDP) resistance in ovarian cancer cells. Ovarian cancer cell viability was assessed by the Cell Counting kit-8 assay; apoptosis and cell cycle progression were determined by flow cytometry; the relative expression levels of microRNA (miR)-374a and forkhead box O1 (FOXO1) were analyzed using reverse transcription-quantitative PCR; the binding ability of miR-374a to FOXO1 was assessed by the dual-luciferase reporter assay; cellular sensitivity to DDP was detected using the MTT assay; and finally, the protein expression levels of FOXO1, p27, and Bcl-2-like-protein 11 (Bim) were analyzed by western blotting. Propofol reduced viability, promoted apoptosis and decreased miR-374a expression levels in A2780 cells. In addition, the viability of A2780/DDP cells in the propofol + DDP treatment group was significantly inhibited, and the apoptotic rate was increased. In addition, miR-374a overexpression increased cell viability and the proportion of cells in the S phase, and decreased the proportion of cells in the G0/G1 phase. Conversely, genetic knockdown of miR-374a exerted the opposite effects on cell viability and cell cycle progression. Moreover, miR-374a was demonstrated to bind to FOXO1. Propofol promoted the expression of FOXO1, p27 and Bim, induced cell cycle arrest and decreased ovarian cancer cell viability. In addition, treatment with propofol and DDP regulated FOXO1 and increased apoptosis of ovarian cancer cells. In conclusion, propofol downregulated miR-374a and modulated the FOXO1 pathway to reduce proliferation and DDP resistance in ovarian cancer cells.

Dexmedetomidine Regulates Proliferation, Apoptosis, Migration, and Invasion in Ovarian Cancer Cells via MiR-155-HIF-1α Axis

BACKGROUND Dexmedetomidine (DMED) is widely used as an adjuvant anesthetic, but how DMED regulates biological behavior of OC cells remains an area of active research. This study investigated the mechanism by which DMED regulates the proliferation, apoptosis, migration, and invasion abilities of OC cells. MATERIAL AND METHODS We determined the optimal concentration of DMED for use in treating SKOV3 cells. The biological activities of DMED-treated SKOV3 cells following transfection with miR-155 inhibitor or si-HIF-1alpha were measured by CCK-8 assay, flow cytometry, wound healing assay, and Transwell assay. qRT-PCR and Western blot analysis were performed to assess the expression levels of apoptotic-related caspase-3 and Mcl-1. Luciferase reporter assay verified the targeting relationship of miR-155 and HIF-1alpha. RESULTS miR-155 was downregulated while HIF-1alpha was upregulated in SKOV3 cells. DMED dose-dependently reduced HIF-1alpha expression in SKOV3 cells, and upregulated the expression of miR-155. DMED inhibited the proliferation, migration and invasion abilities of OC cells, but also contributed to apoptosis of SKOV3 cells, while transfection of miR-155 inhibitor inhibited the effect of DMED on SKOV3 cells. In contrast, transfection with si-HIF-1alpha enhanced the effects of DMED on SKOV3 cells. HIF-1alpha was found to be a target gene of miR-155. CONCLUSIONS Our results suggest that DMED blocks cell proliferation, migration, and invasion and accelerates cell apoptosis in OC.

Photobiomodulation Enhances Cisplatin Cytotoxicity in a Culture Model with Oral Cell Lineages

Cisplatin plays a central role in cancer chemotherapy, but resistance to this drug remains a major obstacle in treatment. Drawbacks related to cisplatin failure may be associated with cell energy metabolism. This study investigated whether photobiomodulation (PBM) can potentiate the effects of cisplatin on keratinocytes (HaCat) and cancer cells (SCC25 and HN12). Cells were treated with laser (GaAlAs; 660 nm; 60 mW; 0.33 J; 2.14 W cm^-2 ; 11.7 J cm^-2 and 6 s) and cisplatin (7.8 μg mL^-1 ) to evaluate cell viability, Ki-67, VEGF, TGF-β1, EGF expression and ROS production. Observations were validated in the SCC25 cell lineage, where the type of cell death (necrosis/apoptosis) and the amount of ATP were assessed. Cell lineages showed increased sensitivity to cisplatin associated with PBM (Cis-PBM). Ki-67 was augmented in all cell lineages treated with Cis-PBM when compared to cisplatin alone (Cis). Cis or Cis-PBM significantly decreased VEGF expression in cancer cells, while no changes were seen in the expression of TGF-β1 or EGF compared to control. ROS levels were similar in the Cis and Cis-PBM groups. Cells treated with Cis-PBM died by apoptosis, leading to greater consumption of ATP. These observations suggest that PBM may potentiate the effects of cisplatin, leading to increased drug cytotoxicity and enhanced cell death.

ERK Regulates HIF1α-Mediated Platinum Resistance by Directly Targeting PHD2 in Ovarian Cancer

PURPOSE

Up to 80% of patients with ovarian cancer develop platinum resistance over time to platinum-based chemotherapy. Increased HIF1α level is an important mechanism governing platinum resistance in platinum-resistant ovarian cancer (PROC). However, the mechanism regulating HIF1α stability in PROC remains largely unknown. Here, we elucidate the mechanism of HIF1α stability regulation in PROC and explore therapeutic approaches to overcome cisplatin resistance in ovarian cancer.

EXPERIMENTAL DESIGN

We first used a quantitative high-throughput combinational screen (qHTCS) to identify novel drugs that could resensitize PROC cells to cisplatin. Next, we evaluated the combination efficacy of inhibitors of HIF1α (YC-1), ERK (selumetinib), and TGFβ1 (SB431542) with platinum drugs by in vitro and in vivo experiments. Moreover, a novel TGFβ1/ERK/PHD2-mediated pathway regulating HIF1α stability in PROC was discovered.

RESULTS

YC-1 and selumetinib resensitized PROC cells to cisplatin. Next, the prolyl hydroxylase domain-containing protein 2 (PHD2) was shown to be a direct substrate of ERK. Phosphorylation of PHD2 by ERK prevents its binding to HIF1α, thus inhibiting HIF1α hydroxylation and degradation-increasing HIF1α stability. Significantly, ERK/PHD2 signaling in PROC cells is dependent on TGFβ1, promoting platinum resistance by stabilizing HIF1α. Inhibition of TGFβ1 by SB431542, ERK by selumetinib, or HIF1α by YC-1 efficiently overcame platinum resistance both in vitro and in vivo. The results from clinical samples confirm activation of the ERK/PHD2/HIF1α axis in patients with PROC, correlating highly with poor prognoses for patients.

CONCLUSIONS

HIF1α stabilization is regulated by TGFβ1/ERK/PHD2 axis in PROC. Hence, inhibiting TGFβ1, ERK, or HIF1α is potential strategy for treating patients with PROC.

Glycolytic enzyme hexokinase II is a putative therapeutic target in B-cell malignant lymphoma

Hexokinase II (HXKII) is a key regulator of glucose metabolism that converts glucose to glucose 6-phosphate. Furthermore, HXKII blocks mitochondria-dependent apoptosis by inhibiting the release of cytochrome c. HXKII overexpression is frequently observed in several types of cancer and confers chemoresistance to cancer cells. In the present study, we found that compared with cell lines generated from diffuse large-B-cell lymphoma (DLBCL) patients, cell lines with features of Burkitt lymphoma have higher levels of HXKII because of the activation of both c-MYC and HIF-1. Under normoxia, HXKII levels were correlated with the growth ability of each B-cell lymphoma cell line. HXKII levels were further enhanced when the B-cell lymphoma cells were cultured under hypoxia. The high levels of HXKII induced by hypoxia conferred cisplatin resistance in all tested B-cell lymphoma cell lines. The HDAC inhibitor panobinostat significantly suppressed HXKII expression under both normoxic and hypoxic conditions. Importantly, panobinostat reversed the anti-lymphoma action of cisplatin, and this effect was diminished by hypoxia. These data suggest that HXKII plays different roles, including in the regulation of glycolysis and inhibition of apoptosis, depending on its expression levels. Furthermore, inhibition of HXKII expression by panobinostat may represent a new and attractive strategy to overcome cisplatin resistance.

Sequential combination of cisplatin with eugenol targets ovarian cancer stem cells through the Notch-Hes1 signalling pathway

Background

Ovarian carcinomas are the deadliest gynecological malignancies owing to their high rate of recurrence and high resistance to platinum-based chemotherapy. Recent studies have shown platinum-dependent enrichment of ovarian tumors with side population as well as cancer stem cells, which are highly resistant to the treatment. To overcome this treatment-limiting factor, we sought to combine cisplatin with eugenol, a natural substance known to have anti-cancer effects.

Methods

The efficiency of combining cisplatin with eugenol was first tested in vitro on two ovarian cancer cell lines SKOV3 and OV2774 using the WST1 and the flow cytometry techniques. The effect of this combination on ovarian cancer stem cells was determined by the tumorsphere formation assay, while the implication of the Notch pathway was evaluated post-ectopic expression of the Hes1 gene. The resulting changes in the expression of several markers was assessed by immunoblotting, immunofluorescence as well as quantitative RT-PCR. Cell sorting was also used to isolate specific ovarian cancer sub-population of cells. Furthermore, tumor-bearing mouse models were utilized to prove the potential therapeutic value of the cisplatin/eugenol combination treatment in vivo.

Results

We have shown that adding eugenol to cisplatin-treated ovarian cancer cells synergistically inhibited their growth and survival through induction of apoptosis. Importantly, this sequential inhibition strongly reduced the proportion of side population cells and suppressed cisplatin-dependent enrichment in ovarian cancer stem cells. Additionally, while increase in the level of Hes1 promoted stemness and enhanced resistance to cisplatin, cisplatin/eugenol cotreatment inhibited the Notch-Hes1 pathway and strongly downregulated the drug resistance ABC transporter genes. These findings were confirmed in vivo by showing that cisplatin/eugenol cotherapy inhibited tumor growth in animals, reduced the proportion and self-renewal capacities of cancer stem cells and significantly improved disease-free survival of tumor-bearing animals compared with either therapy alone.

Conclusions

These results indicate that cisplatin/eugenol sequential combination could be of great therapeutic value for ovarian cancer patients through targeting the Notch-Hes1 pathway and the consequent elimination of the resistant cancer stem cells.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1360-3) contains supplementary material, which is available to authorized users.

Combinations of the antioxidants sulforaphane or curcumin and the conventional antineoplastics cisplatin or doxorubicin as prospects for anticancer chemotherapy

Drugs used in clinical oncology have narrow therapeutic indices with adverse toxicity often involving oxidative damage. Chemoresistance to these conventional antineoplastics is usually mediated by oxidative stress-upregulated pathways such as those of nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor-1 alpha (HIF-1α). Accordingly, the use of antioxidants in combinational approaches has begun to be considered for fighting cancer because of both the protective role against adverse effects and the ability to sensitize chemoresistant cancer cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been identified as a mediator of the cytoprotection but it is not regularly associated with tumor chemosensitization. However, some Nrf2 inducers could be exerting cytoprotective and chemosensitizing roles through a simple integrated mechanism in which the cellular level of reactive oxygen species is controlled, thus inhibiting the oxidative damage in non-target tissues and the tumor chemoresistance mediated by NF-κB or HIF-1α. As examples to show the general idea of this antioxidant combination chemotherapy, this review explores the preclinical information available for four combinations, each composed by a paradigmatic oncological drug (cisplatin or doxorubicin) and a recognized antioxidant (sulforaphane or curcumin). The issues for translating these outcomes to clinical trials are briefly discussed.

Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance

How altered metabolism contributes to chemotherapy resistance in cancer cells remains unclear. Through a metabolism-related kinome RNAi screen, we identified inositol-trisphosphate 3-kinase B (ITPKB) as a critical enzyme that contributes to cisplatin-resistant tumor growth. We demonstrated that inositol 1,3,4,5-tetrakisphosphate (IP4), the product of ITPKB, plays a critical role in redox homeostasis upon cisplatin exposure by reducing cisplatin-induced ROS through inhibition of a ROS-generating enzyme, NADPH oxidase 4 (NOX4), which promotes cisplatin-resistant tumor growth. Mechanistically, we identified that IP4 competes with the NOX4 cofactor NADPH for binding and consequently inhibits NOX4. Targeting ITPKB with shRNA or its small-molecule inhibitor resulted in attenuation of NOX4 activity, imbalanced redox status, and sensitized cancer cells to cisplatin treatment in patient-derived xenografts. Our findings provide insight into the crosstalk between kinase-mediated metabolic regulation and platinum-based chemotherapy resistance in human cancers. Our study also suggests a distinctive signaling function of IP4 that regulates NOX4. Furthermore, pharmaceutical inhibition of ITPKB displayed synergistic attenuation of tumor growth with cisplatin, suggesting ITPKB as a promising synthetic lethal target for cancer therapeutic intervention to overcome cisplatin resistance.

H2S inhalation-induced energy metabolism disturbance is involved in LPS mediated hepatocyte apoptosis through mitochondrial pathway

Hydrogen sulfide (H₂S) is a toxic gas and one of the air pollutants of great concern. High-concentrated H₂S can induce energy metabolism disturbance and apoptosis. However, the mechanism of H₂S-induced liver injuries is unknown. Lipopolysaccharide (LPS), the main component of endotoxin, can cause fulminant hepatitis. Here, we evaluated the effects of H₂S combined with LPS on the energy metabolism and apoptosis pathway in the liver using a one-day-old chicken as a model. Our results showed that the expression levels of energy metabolism-related genes (AMP-activated protein kinase (AMPK), Hypoxia-inducible factor-1 (HIF-1), aconitase 2 (ACO2), hexokinase1 (HK1), hexokinase 2 (HK2), lactate dehydrogenase A (LDHA), lactate dehydrogenase B (LDHB), phosphofructokinase (PFK), pyruvate kinase (PK) and succinate dehydrogenase B (SDHB)) tended to decrease, that the status of apoptosis increased, and that the expression levels of apoptosis-related genes (caspase3, BCL2, and bax) increased in H₂S group, suggesting that H₂S exposure disturbed the energy metabolism in the liver and induced hepatocyte apoptosis through the mitochondrial pathway. In addition, H₂S combined with the LPS aggravated the level of energy metabolism disorders and apoptosis, indicating that H₂S inhalation-induced energy metabolism disturbance is involved in LPS-mediated hepatocyte apoptosis through the mitochondrial pathway.

Cisplatin-Based Chemotherapy of Human Cancers

Cisplatin (cis-diammine-dichloro-platinum II) was initially discovered to prevent the growth of Escherichia coli and was further recognized for its anti-neoplastic and cytotoxic effects on cancer cells. Administered intravenously to humans, cisplatin is used as first-line chemotherapy treatment for patients diagnosed with various types of malignancies, such as leukemia, lymphomas, breast, testicular, ovarian, head and neck, and cervical cancers, and sarcomas. Once cisplatin enters the cell it exerts its cytotoxic effect by losing one chloride ligand, binding to DNA to form intra-strand DNA adducts, and inhibiting DNA synthesis and cell growth. The DNA lesions formed from cisplatin-induced DNA damage activate DNA repair response via NER (nuclear excision repair system) by halting cisplatin-induced cell death by activation of ATM (ataxia telangiectasia mutated) pathway. Although treatment has been shown to be effective, many patients experience relapse due to drug resistance. As a result, other platinum compounds such as oxaliplatin and carboplatin have since been used and have shown some levels of effectiveness. In this review, the clinical applications of cisplatin are discussed with a special emphasis on its use in cancer chemotherapy.

Identification of exosomal and non‑exosomal microRNAs associated with the drug resistance of ovarian cancer

MicroRNAs (miRNAs) serve important roles in drug‑resistance; however, exosomal miRNAs associated with drug‑resistance in ovarian cancer (OC) have not been reported to date. The current study aimed to analyze the drug resistance‑associated exosomal miRNAs in original OC cells and their derived exosomes using microarray data downloaded from the Gene Expression Omnibus database (series GSE76449). The chemosensitive OC cell lines SKOV3_ip1, A2780_PAR and HEYA8, as well as the chemoresistant cell lines SKOV3_TR, A2780_CP20 and HEYA8_MDR, were investigated. Differentially expressed miRNAs (DE‑miRNAs) were identified using the limma method, and their mRNA targets were predicted using the miRWalk and LinkedOmics database. Functions of target genes were analyzed with DAVID tool, while TCGA data were used to explore the survival association of identified miRNAs. According to the results, 28 DE‑miRNAs were found to be common in exosomal and original samples of A2780_CP20 cells, among which the functions of 5 miRNAs were predicted (including miR‑146b‑5p, miR‑509‑5p, miR‑574‑3p, miR‑574‑5p and miR‑760). In addition, 16 and 35 DE‑miRNAs were detected for HEYA8_MDR and SKOV3_TR, respectively, with the functions of 4 of these miRNAs predicted for each cell line (HEYA8_MDR: miR‑30a‑3p, miR‑30a‑5p, miR‑612 and miR‑617; SKOV3_TR: miR‑193a‑5p, miR‑423‑3p, miR‑769‑5p and miR‑922). It was also reported that miR‑183‑5p was the only one common miRNA among the three cell lines. Furthermore, miR‑574‑3p, miR‑30a‑5p and miR‑922 may regulate CUL2 to mediate HIF‑1 cancer signaling pathway, while miR‑183‑5p may modulate MECP2, similar to miR‑760, miR‑30a‑5p and miR‑922, to influence cell proliferation. Finally, the downregulated miR‑612 may promote the expression of TEAD3 via the Hippo signaling pathway, and this miRNA was associated with poor prognosis. In conclusion, the findings of the present study suggested several underlying miRNA targets for improving the chemotherapy sensitivity of OC.