Molecular mechanisms of platinum‑based chemotherapy resistance in ovarian cancer (Review)

The impact of PARP inhibitors in the whole scenario of ovarian cancer management: A systematic review and network meta-analysis

BACKGROUND

Carboplatin is still the cornerstone of the first-line treatment in advanced Epithelial Ovarian Cancer (aEOC) management and the clinical response to platinum-derived agents remains the major predictor of long-term outcomes.

PATIENT AND METHODS

We aimed to identify the best treatment of the aEOC in terms of efficacy and safety, considering all treatment phases. A systematic literature search has been done to compare all treatments in aEOC population. Randomized trials with available survival and safety data published in the 2011-2022 timeframe were enclosed. Only trials reporting the BRCA or HRD (Homologous Recombination Deficiency) status were considered.

DATA EXTRACTION AND SYNTHESIS

A ranking of treatment schedules on the progression-free survival (PFS) endpoint was performed. The random-effect model was used to elaborate and extract data. The Network Meta-Analysis (NMA) by Bayesian model was performed by STATA v17. Data on PFS were extracted in terms of Hazard ratio with relative confidence intervals.

RESULTS

This NMA involved 18 trials for a total of 9105 patients. Within 12 treatment groups, we performed 3 different sensitivity analyses including "all comers" Intention to Treat (ITT) population, BRCA-mutated (BRCAm), and HRD subgroups, respectively. Considering the SUCRA-reported cumulative PFS probabilities, we showed that in the ITT population, the inferred best treatment was niraparib plus bevacizumab with a SUCRA of 96.7. In the BRCAm subgroup, the best SUCRA was for olaparib plus chemotherapy (96,9). The HRD population showed an inferred best treatment for niraparib plus bevacizumab (SUCRA 98,4). Moreover, we reported a cumulative summary of PARPi toxicity, in which different 3-4 grade toxicity profiles were observed, despite the PARPi "class effect" in terms of efficacy.

CONCLUSIONS

Considering all aEOC subgroups, the best therapeutical option was identified as PARPi plus chemotherapy and/or antiangiogenetic agents, suggesting the relevance of combinatory approaches based on molecular profile. This work underlines the potential value of "chemo-free" regimens to prolong the platinum-free interval (PFI).

Enzymatically crosslinked magnetic starch-grafted poly(tannic acid) hydrogel for "smart" cancer treatment: An in vitro chemo/hyperthermia therapy study

A novel strategy was designed and developed based of horseradish peroxidase (HRP)-mediated crosslinking of tyramine-functionalized starch (Tyr-St), tannic acid (TA) and phenolated-magnetic nanoparticles (Fe3O4-PhOH NPs), and simultaneous loading of doxorubicin hydrochloride (Dox) to afford a pH-responsive magnetic hydrogel-based drug delivery system (DDS) for synergistic in vitro chemo/hyperthermia therapy of human breast cancer (MCF-7) cells. The developed St-g-PTA/Fe3O4 magnetic hydrogel showed porous micro-structure with saturation magnetization (δs) value of 19.2 emu g-1 for Fe3O4 NPs content of ∼7.4 wt%. The pore sizes of the St-g-PTA/Fe3O4 hydrogel was calculated to be 2400 ± 200 nm-2. In vitro drug release experiments exhibited the developed DDS has pH-dependent drug release behavior, while at physiological pH (7.4) released only 30 % of the loaded drug after 100 h. Human serum albumin (HSA) adsorption capacities of the synthesized St/Fe3O4 and St-g-PTA/Fe3O4 magnetic hydrogels were obtained as 86 ± 2.2 and 77 ± 1.9 μgmg-1, respectively. The well-known MTT-assay approved the cytocompatibility of the developed St-g-PTA/Fe3O4 hydrogel, while the Dox-loaded system exhibited higher anti-cancer activity than those of the free Dox as verified by MTT-assay, and optical as well as florescent microscopies imaging. The synergistic chemo/hyperthermia therapy effect was also verified for the developed St-g-PTA/Fe3O4-Dox via hot water approach.

Meta-analysis of microarray data to determine gene indicators involved in the cisplatin resistance in ovarian cancer

BACKGROUND

Significant miss-expressed gene indicators contributing to cisplatin resistance in ovarian cancer have not been completely understood. It seems that several regulatory genes and signaling pathways are associated with the emergence of the chemo-resistant phenotype.

AIMS

Here, a meta-analysis approach was adopted to assess deregulated genes involved in relapse after the first line of chemotherapy (cisplatin).

METHODS AND RESULTS

To do so, six ovarian cancer libraries were gathered from GEO repository. Batch effect removal and quality assessment, and boxplots and PCA were performed using SVA and ggplot2 packages in R, respectively. Cisplatin-resistant and -sensitive ovarian cancer groups were compared with find genes with significant expression changes using linear regression models in the LIMMA R package. The significance threshold for DEGs was taken as adj p-value < .05 and - 1 > logFC > 1. A total of 261 genes were identified to have significant differential expression levels in the cisplatin-resistant versus cisplatin-sensitive group. Among the 10 top up-regulated and down-regulated genes, PITX2, SNCA, and EPHA7 (up), as well as TMEM98 (down) are indirect upstream regulators of PI3K/AKT signaling pathway, contributing greatly to the development of chemo-resistance in cancer via promoting cell proliferation, survival, and cell cycle progression as well as inhibiting apoptosis. Moreover, a comprehensive assessment of DEGs revealed the dysregulation of not only membrane ion channels KCa1.1, Kv4, and CACNB4, affecting cell excitability, proliferation, and apoptosis but also cell adhesion proteins COL4A6, EPHA3, and CD9, affecting the attachment of normal cells to ECM and apoptosis, introducing good options to reverse cisplatin resistance.

CONCLUSION

Our results predict and suggest that upstream regulators of PI3K/AKT signaling pathway, ion channels, and cell adhesion proteins play important roles in cisplatin resistance development in ovarian cancer.

Beyond Sterilization: A Comprehensive Review on the Safety and Efficacy of Opportunistic Salpingectomy as a Preventative Strategy for Ovarian Cancer

Ovarian cancer (OC) is Canada's third most common gynecological cancer, with an estimated 3000 new cases and 1950 deaths projected in 2022. No effective screening has been found to identify OC, especially the most common subtype, high-grade serous carcinoma (HGSC), at an earlier, curable stage. In patients with hereditary predispositions such as BRCA mutations, the rates of HGSC are significantly elevated, leading to the use of risk-reducing salpingo-oophorectomy as the key preventative intervention. Although surgery has been shown to prevent HGSC in high-risk women, the associated premature menopause has adverse long-term sequelae and mortality due to non-cancer causes. The fact that 75% of HGSCs are sporadic means that most women diagnosed with HGSC will not have had the option to avail of either screening or prevention. Recent research suggests that the fimbrial distal fallopian tube is the most likely origin of HGSC. This has led to the development of a prevention plan for the general population: opportunistic salpingectomy, the removal of both fallopian tubes. This article aims to compile and review the studies evaluating the effect of opportunistic salpingectomy on surgical-related complications, ovarian reserve, cost, and OC incidence when performed along with hysterectomy or instead of tubal ligation in the general population.

The microbiome and ovarian cancer: insights, implications, and therapeutic opportunities

Ovarian cancer is the leading cause of gynecologic cancer death in the United States. Most ovarian cancer patients are diagnosed with advanced-stage disease, which poses a challenge for early detection and effective treatment. At present, cytoreductive surgery and platinum-based chemotherapy are foundational for patients with newly diagnosed ovarian cancer, but unfortunately, most patients will recur and die of their disease. Therefore, there is a significant need to seek innovative, novel approaches for early detection and to overcome chemoresistance for ovarian cancer patients. The microbiome, comprising diverse microbial communities inhabiting various body sites, is vital in maintaining human health. Changes to the diversity and composition of the microbial communities impact the microbiota-host relationship and are linked to diseases, including cancer. The microbiome contributes to carcinogenesis through various mechanisms, including altered host immune response, modulation of DNA repair, upregulation of pro-inflammatory pathways, altered gene expression, and dysregulated estrogen metabolism. Translational and clinical studies have demonstrated that specific microbes contribute to ovarian cancer development and impact chemotherapy’s efficacy. The microbiome is malleable and can be altered through different approaches, including diet, exercise, medications, and fecal microbiota transplantation. This review provides an overview of the current literature regarding ovarian cancer and the microbiome of female reproductive and gastrointestinal tracts, focusing on mechanisms of carcinogenesis and options for modulating the microbiota for cancer prevention and treatment. Advancing our understanding of the complex relationship between the microbiome and ovarian cancer may provide a novel approach for prevention and therapeutic modulation in the future.

PINK1-PTEN axis promotes metastasis and chemoresistance in ovarian cancer via non-canonical pathway

BACKGROUND

Ovarian cancer is commonly associated with a poor prognosis due to metastasis and chemoresistance. PINK1 (PTEN-induced kinase 1) is a serine/threonine kinase that plays a crucial part in regulating various physiological and pathophysiological processes in cancer cells.

METHODS

The ATdb database and "CuratedOvarianData" were used to evaluate the effect of kinases on ovarian cancer survival. The gene expression in ovarian cancer cells was detected by Western blot and quantitative real-time PCR. The effects of gene knockdown or overexpression in vitro were evaluated by wound healing assay, cell transwell assay, immunofluorescence staining, immunohistochemistry, and flow cytometry analysis. Mass spectrometry analysis, protein structure analysis, co-immunoprecipitation assay, nuclear-cytoplasmic separation, and in vitro kinase assay were applied to demonstrate the PINK1-PTEN (phosphatase and tensin homolog) interaction and the effect of this interaction. The metastasis experiments for ovarian cancer xenografts were performed in female BALB/c nude mice.

RESULTS

PINK1 was strongly associated with a poor prognosis in ovarian cancer patients and promoted metastasis and chemoresistance in ovarian cancer cells. Although the canonical PINK1/PRKN (parkin RBR E3 ubiquitin protein ligase) pathway showed weak effects in ovarian cancer, PINK1 was identified to interact with PTEN and phosphorylate it at Serine179. Remarkably, the phosphorylation of PTEN resulted in the inactivation of the phosphatase activity, leading to an increase in AKT (AKT serine/threonine kinase) activity. Moreover, PINK1-mediated phosphorylation of PTEN impaired the nuclear import of PTEN, thereby enhancing the cancer cells' ability to resist chemotherapy and metastasize.

CONCLUSIONS

PINK1 interacts with and phosphorylates PTEN at Serine179, resulting in the activation of AKT and the inhibition of PTEN nuclear import. PINK1 promotes ovarian cancer metastasis and chemotherapy resistance through the regulation of PTEN. These findings offer new potential therapeutic targets for ovarian cancer management.

Snail transcription factors as key regulators of chemoresistance, stemness and metastasis of ovarian cancer cells

Ovarian cancer is one of the deadliest gynecological malignancies among women. The reason for this outcome is the frequent acquisition of cancer cell resistance to platinum-based drugs and unresponsiveness to standard therapy. It has been increasingly recognized that the ability of ovarian cancer cells to adopt more aggressive behavior (mainly through the epithelial-to-mesenchymal transition, EMT), as well as dedifferentiation into cancer stem cells, significantly affects drug resistance acquisition. Transcription factors in the Snail family have been implicated in ovarian cancer chemoresistance and metastasis. In this article, we summarize published data that reveal Snail proteins not only as key inducers of the EMT in ovarian cancer but also as crucial links between the acquisition of ovarian cancer stem properties and spheroid formation. These Snail-related characteristics significantly affect the ovarian cancer cell response to treatment and are related to the acquisition of chemoresistance.

Auranofin Induces Lethality Driven by Reactive Oxygen Species in High-Grade Serous Ovarian Cancer Cells

High-grade serous ovarian cancer (HGSOC) accounts for 70% of ovarian cancer cases, and the survival rate remains remarkably low due to the lack of effective long-term consolidation therapies. Clinical remission can be temporarily induced by platinum-based chemotherapy, but death subsequently results from the extensive growth of a platinum-resistant component of the tumor. This work explores a novel treatment against HGSOC using the gold complex auranofin (AF). AF primarily functions as a pro-oxidant by inhibiting thioredoxin reductase (TrxR), an antioxidant enzyme overexpressed in ovarian cancer. We investigated the effect of AF on TrxR activity and the various mechanisms of cytotoxicity using HGSOC cells that are clinically sensitive or resistant to platinum. In addition, we studied the interaction between AF and another pro-oxidant, L-buthionine sulfoximine (L-BSO), an anti-glutathione (GSH) compound. We demonstrated that AF potently inhibited TrxR activity and reduced the vitality and viability of HGSOC cells regardless of their sensitivities to platinum. We showed that AF induces the accumulation of reactive oxygen species (ROS), triggers the depolarization of the mitochondrial membrane, and kills HGSOC cells by inducing apoptosis. Notably, AF-induced cell death was abrogated by the ROS-scavenger N-acetyl cysteine (NAC). In addition, the lethality of AF was associated with the activation of caspases-3/7 and the generation of DNA damage, effects that were also prevented by the presence of NAC. Finally, when AF and L-BSO were combined, we observed synergistic lethality against HGSOC cells, which was mediated by a further increase in ROS and a decrease in the levels of the antioxidant GSH. In summary, our results support the concept that AF can be used alone or in combination with L-BSO to kill HGSOC cells regardless of their sensitivity to platinum, suggesting that the depletion of antioxidants is an efficient strategy to mitigate the course of this disease.

Hsa_circ_0000585 promotes chemoresistance to cis-platin in epithelial cells of ovarian cancer by modulating autophagy

BACKGROUND

Chemoresistance, i.e., resistance to cisplatin (DDP), has been a major obstacle to ovarian cancer treatment. It has been found that circular RNAs (circRNAs) play vital roles in the tumorigenesis various cancers by regulating autophagy, while few studies focusing on cisplatin-resistance ovarian cancer (CROC).

METHODS

The expressions of the circRNAs were detected by qRT-PCR. Short hairpin RNA targeting circRNA was used to explore the biological functions of the circRNA. Cell viability, autophagic flux, immunofluorescence, and xenograft tumors experiments were performed to further illustrate the underlying mechanisms.

RESULTS

Hsa_circ_0000585 was increased in cisplatin-resistant SKOV3/DDP cells. Stably knocking down hsa_circRNA_0000585 expression in SKOV3/DDP cells was established by RNA interference. We found that downregulation of hsa_circ_0000585 significantly enhanced the sensitivity of DDP/SkOV3 cells to DDP. In vivo study, hsa_circRNA_0000585 knockdown significantly decreased tumor volume in nude mice. Under the measurements of western blot and cellular immunofluorescence, hsa_circ_0000585 knockdown significantly inhibited the expression of Beclin1 and P62, indicating the autophagic flux was inhibited. Administrations with autophagic inhibitor "Chloroquine (CQ)" and autophagy activator "QX77" further confirmed that hsa_circ_0000585 knockdown resulted in autophagy inhibition.

CONCLUSIONS

Overall, this study provided a new insight into the role of circRNAs in the mechanism of DDP-resistance in ovarian cancer. Hsa_circRNA_0000585 may be promising therapeutic targets for the enhancement of the sensitivity of ovarian cancer cells to cisplatin-mediated chemotherapy.

Identification of Potential Protein Targets in Extracellular Vesicles Isolated from Chemotherapy-Treated Ovarian Cancer Cells

Despite the ongoing clinical trials and the introduction of novel treatments over the past few decades, ovarian cancer remains one of the most fatal malignancies in women worldwide. Platinum- and paclitaxel-based chemotherapy is effective in treating the majority of patients with ovarian cancer. However, more than 70% of patients experience recurrence and eventually develop chemoresistance. To improve clinical outcomes in patients with ovarian cancer, novel technologies must be developed for identifying molecular alterations following drug-based treatment of ovarian cancer. Recently, extracellular vesicles (EVs) have gained prominence as the mediators of tumor progression. In this study, we used mass spectrometry to identify the changes in EV protein signatures due to different chemotherapeutic agents used for treating ovarian cancer. By examining these alterations, we identified the specific protein induction patterns of cisplatin alone, paclitaxel alone, and a combination of cisplatin and paclitaxel. Specifically, we found that drug sensitivity was correlated with the expression levels of ANXA5, CD81, and RAB5C in patients receiving cisplatin with paclitaxel. Our findings suggest that chemotherapy-induced changes in EV protein signatures are crucial for the progression of ovarian cancer.

Does the addition of metformin to carboplatin treatment decreases ovarian reserve damage associated with carboplatin usage?

BACKGROUND

We aimed to determine whether adding metformin to carboplatin treatment would reduce the damage to ovarian reserve associated with carboplatin use.

METHODS

We included 35 adult female non-pregnant albino Wistar rats approximately three months old, weighing 220-310 g. The rats were divided into five groups of seven rats according to the treatment they received. Carboplatin and salin was given to Group 2, and carboplatin plus metformin was given to Group 3. Group 4 was administered only metformin. Group 5 was administered only salin. Carboplatin was given to Groups 2 and 3 as a single dose on the 15th day, while metformin was given to Groups 3 and 4 during the 28-day experiment. After oophorectomy, histopathologic analyses of primordial, primary, secondary, and tertiary Graff follicles according to the epithelial cells surrounding the oocyte and total follicular number were conducted per section. Serum Anti-Mullerian Hormone (AMH), tissue catalase, and malonyl dialdehyde levels were measured and compared within each group.

RESULTS

The baseline and 15th-day serum AMH values of the menstrual cycle were compared among the groups, and no statistically significant differences were observed (p > 0.05). Group 3, which was given both carboplatin and metformin, had statistically significantly higher 28th-day AMH levels than Group 2, which was given only carboplatin and saline (p < 0.001). The number of primordial follicles in Group 3 was found to be statistically significantly higher than in Group 2 (p < 0.001). Tissue catalase enzyme levels in Group 3 were statistically significantly higher than in Group 2 (p < 0.001). Tissue malondialdehyde levels in Group 2 were statistically significantly higher than tissue malondialdehyde levels in Groups 3 and 4 (p < 0.001).

CONCLUSIONS

Metformin may attenuate carboplatin-induced ovarian damage, possibly through its antioxidative effects.

CT radiomics prediction of CXCL9 expression and survival in ovarian cancer

BACKGROUND

C-X-C motif chemokine ligand 9 (CXCL9), which is involved in the pathological processes of various human cancers, has become a hot topic in recent years. We developed a radiomic model to identify CXCL9 status in ovarian cancer (OC) and evaluated its prognostic significance.

METHODS

We analyzed enhanced CT scans, transcriptome sequencing data, and corresponding clinical characteristics of CXCL9 in OC using the TCIA and TCGA databases. We used the repeat least absolute shrinkage (LASSO) and recursive feature elimination(RFE) methods to determine radiomic features after extraction and normalization. We constructed a radiomic model for CXCL9 prediction based on logistic regression and internal tenfold cross-validation. Finally, a 60-month overall survival (OS) nomogram was established to analyze survival data based on Cox regression.

RESULTS

CXCL9 mRNA levels and several other genes involving in T-cell infiltration were significantly relevant to OS in OC patients. The radiomic score (rad_score) of our radiomic model was calculated based on the five features for CXCL9 prediction. The areas under receiver operating characteristic (ROC) curves (AUC-ROC) for the training cohort was 0.781, while that for the validation cohort was 0.743. Patients with a high rad_score had better overall survival (P < 0.001). In addition, calibration curves and decision curve analysis (DCA) showed good consistency between the prediction and actual observations, demonstrating the clinical utility of our model.

CONCLUSION

In patients with OC, the radiomics signature(RS) of CT scans can distinguish the level of CXCL9 expression and predict prognosis, potentially fulfilling the ultimate purpose of precision medicine.

Therapeutic strategies targeting folate receptor α for ovarian cancer

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and presents a major clinical challenge due to limited treatment options. Folate receptor alpha (FRα), encoded by the FOLR1 gene, is an attractive therapeutically target due to its prevalent and high expression in EOC cells. Recent basic and translational studies have explored several modalities, such as antibody-drug conjugate (ADC), monoclonal antibodies, small molecules, and folate-drug conjugate, to exploit FRα for EOC treatment. In this review, we summarize the function of FRα, and clinical efficacies of various FRα-based therapeutics. We highlight mirvetuximab soravtansine (MIRV), or Elahere (ImmunoGen), the first FRα-targeting ADC approved by the FDA to treat platinum-resistant ovarian cancer. We discuss potential mechanisms and management of ocular adverse events associated with MIRV administration.

Mitophagy-related long non-coding RNA signature predicts prognosis and drug response in Ovarian Cancer

BACKGROUND

Ovarian cancer (OC) is the most malignant tumor with the worst prognosis in female reproductive system. Mitophagy and long non-coding RNAs (lncRNAs) play pivotal roles in tumorigenesis, development, and drug resistance. The effects of mitophagy-related lncRNAs on OC prognosis and therapeutic response remain unelucidated.

METHODS

We retrieved OC-related RNA sequence, copy number variation, somatic mutation, and clinicopathological information from The Cancer Genome Atlas database and mitophagy-related gene sets from the Reactome database. Pearson's correlation analysis was used to distinguish mitophagy-related lncRNAs. A prognostic lncRNA signature was constructed using UniCox, LASSO, and forward stepwise regression analysis. Individuals with a risk score above or below the median were classified as high- or low-risk groups, respectively. The risk model was analyzed using the Kaplan-Meier estimator, receiver operating characteristic curve, decision curve analysis, and Cox regression analysis and validated using an internal dataset. LINC00174 was validated in clinical samples and OC cell lines. We also reviewed reports on the role of LINC00174 in cancer. Subsequently, a nomogram model was constructed. Furthermore, the Genomics of Drug Sensitivity in Cancer database was used to explore the relationship between the risk model and anti-tumor drug sensitivity. Gene set variation analysis was performed to assess potential differences in biological functions between the two groups. Finally, a lncRNA prognostic signature-related competing endogenous RNA (ceRNA) network was constructed.

RESULTS

The prognostic signature showed that patients in the high-risk group had a poorer prognosis. The nomogram exhibited satisfactory accuracy and predictive potential. LINC00174 mainly acts as an oncogene in cancer and is upregulated in OC; its knockdown inhibited the proliferation and migration, and promoted apoptosis of OC cells. High-risk patients were more insensitive to cisplatin and olaparib than low-risk patients. The ceRNA network may help explore the potential regulatory mechanisms of lncRNAs.

CONCLUSION

The mitophagy-related lncRNA signature can help estimate the survival and drug sensitivity, the ceRNA network may provide novel therapeutic targets for patients with OC.

Ascites-Derived Organoids to Depict Platinum Resistance in Gynaecological Serous Carcinomas

Gynaecological serous carcinomas (GSCs) constitute a distinctive entity among female tumours characterised by a very poor prognosis. In addition to late-stage diagnosis and a high rate of recurrent disease associated with massive peritoneal carcinomatosis, the systematic acquisition of resistance to first-line chemotherapy based on platinum determines the unfavourable outcome of GSC patients. To explore the molecular mechanisms associated with platinum resistance, we generated patient-derived organoids (PDOs) from liquid biopsies of GSC patients. PDOs are emerging as a relevant preclinical model system to assist in clinical decision making, mainly from tumoural tissue and particularly for personalised therapeutic options. To approach platinum resistance in a GSC context, proficient PDOs were generated from the ascitic fluid of ovarian, primary peritoneal and uterine serous carcinoma patients in platinum-sensitive and platinum-resistant clinical settings from the uterine aspirate of a uterine serous carcinoma patient, and we also induced platinum resistance in vitro in a representative platinum-sensitive PDO. Histological and immunofluorescent characterisation of these ascites-derived organoids showed resemblance to the corresponding original tumours, and assessment of platinum sensitivity in these preclinical models replicated the clinical setting of the corresponding GSC patients. Differential gene expression profiling of a panel of 770 genes representing major canonical cancer pathways, comparing platinum-sensitive and platinum-resistant PDOs, revealed cellular response to DNA damage stimulus as the principal biological process associated with the acquisition of resistance to the first-line therapy for GSC. Additionally, candidate genes involved in regulation of cell adhesion, cell cycles, and transcription emerged from this proof-of-concept study. In conclusion, we describe the generation of PDOs from liquid biopsies in the context of gynaecological serous carcinomas to explore the molecular determinants of platinum resistance.

Mechanisms of autophagy and endoplasmic reticulum stress in the reversal of platinum resistance of epithelial ovarian cancer cells by naringin

OBJECTIVE

Our previous studies showed that naringin (Nar) can effectively reverse the cisplatin resistance of ovarian cancer cells. This study aims to explore the potential mechanism by which Nar reverses cisplatin resistance in ovarian cancer.

METHODS

The proliferative activity of cells was evaluated using CCK8 and cell clone formation assays. Autophagic flux in cells was evaluated via LC3B immunofluorescence and monodansylcadaverine (MDC) staining. The expression levels of autophagy, endoplasmic reticulum (ER) stress, and apoptosis-related proteins were detected via Western blotting. Autophagy and ER stress were regulated using siATG5, siLC3B, rapamycin (Rap), chloroquine (CQ), 4-phenylbutyric acid (4-PBA), and thapsigargin (TG). siATG5 and siLC3B are short interfering RNAs (siRNAs) used to knock down the expression of ATG5 and LC3B genes, respectively.

RESULTS

Nar inhibited autophagy in SKOV3/DDP cells by activating the PI3K/AKT/mTOR pathway. And Nar increased the levels of ER stress-related proteins, namely, P-PERK, GRP78, and CHOP, and promoted apoptosis in SKOV3/DDP cells. Moreover, treatment with the inhibitor of ER stress alleviated apoptosis induced by Nar in SKOV3/DDP cells. In addition, compared to cisplatin or naringin alone, the combination of Nar and cisplatin significantly reduced the proliferative activity of SKOV3/DDP cells. And siATG5, siLC3B, CQ or TG pretreatment further inhibited the proliferative activity of SKOV3/DDP cells. Conversely, Rap or 4-PBA pretreatment alleviated the cell proliferation inhibition caused by Nar combined with cisplatin.

CONCLUSION

Nar not only inhibited the autophagy in SKOV3/DDP cells by regulating the PI3K/AKT/mTOR signalling pathway, but also promoted apoptosis in SKOV3/DDP cells by targeting ER stress. Nar can reverse the cisplatin resistance in SKOV3/DDP cells through these two mechanisms.

Suppression of Metastatic Ovarian Cancer Cells by Bepridil, a Calcium Channel Blocker

Although surgery followed by platinum-based therapy is effective as a standard treatment in the early stages of ovarian cancer, the majority of cases are diagnosed at advanced stages, leading to poor prognosis. Thus, the identification of novel therapeutic drugs is needed. In this study, we assessed the effectiveness of bepridil-a calcium channel blocker-in ovarian cancer cells using two cell lines: SKOV-3, and SKOV-3-13 (a highly metastatic clone of SKOV-3). Treatment of these cell lines with bepridil significantly reduced cell viability, migration, and invasion. Notably, SKOV-3-13 was more sensitive to bepridil than SKOV-3. The TGF-β1-induced epithelial-mesenchymal transition (EMT)-like phenotype was reversed by treatment with bepridil in both cell lines. Consistently, expression levels of EMT-related markers, including vimentin, β-catenin, and Snail, were also substantially decreased by the treatment with bepridil. An in vivo mouse xenograft model was used to confirm these findings. Tumor growth was significantly reduced by bepridil treatment in SKOV-3-13-inoculated mice, and immunohistochemistry showed consistently decreased expression of EMT-related markers. Our findings are the first to report anticancer effects of bepridil in ovarian cancer, and they suggest that bepridil holds significant promise as an effective therapeutic agent for targeting metastatic ovarian cancer.

Glucose-6-phosphate dehydrogenase: a therapeutic target for ovarian cancer

INTRODUCTION

Ovarian cancer (OC) is a gynecological tumor disease, which is usually diagnosed at an advanced stage and has a poor prognosis. It has been established that the glucose metabolism rate of cancer cells is significantly higher than that of normal cells, and the pentose phosphate pathway (PPP) is an important branch pathway for glucose metabolism. Glucose-6-phosphate dehydrogenase (G6PD) is the key rate-limiting enzyme in the PPP, which plays an important role in the initiation and development of cancer (such as OC), and has been considered as a promisinganti-cancer target.

AREAS COVERED

In this review, based on the structure and biological function of G6PD, recent research on the roles of G6PD in the progression, metastasis, and chemoresistance of OC are summarized and accompanied by proposed molecular mechanisms, which may provide a systematic understanding of targeting G6PD for the treatment of patients with OC.

EXPERT OPINION

Accumulating evidence demonstrates that G6PD is a promising target of cancer. The development of G6PD inhibitors for cancer treatment merits broad application prospects.

A biscarbene gold(I)-NHC-complex overcomes cisplatin-resistance in A2780 and W1 ovarian cancer cells highlighting pERK as regulator of apoptosis

PURPOSE

Cisplatin resistance is the major obstacle in the clinical treatment of ovarian cancer patients. Molecular mechanisms of cisplatin resistance are multifaceted. Gold(I)-compounds, i.e. N-heterocyclic carbene-gold(I)-complexes (NHC-Au(I)) has been regarded as promising cytotoxic drug candidates. However, their potential to overcome cisplatin resistance has hardly been addressed yet. Here we investigated the activity of the gold(I) drug auranofin and the NHC-Au(I)-compound MC3 in W1CR and A2780cis cisplatin-resistant ovarian cancer cells.

METHODS

Cytotoxicity of auranofin and MC3 was detected by MTT assay, correlated with intracellular gold(I) content, analyzed by AAS, and with flow cytometric detection of the cell cycle. Insight into cellular redox balance was provided by fluorimetric ROS-formation assay and western blotting thioredoxin (Trx) and Nrf2. The role of ERK was elucidated by using the inhibitor SCH772984 and its impact on cytotoxicity upon co-treatment with cisplatin and Au(I)-compounds, respectively.

RESULTS

MC3 overcomes cisplatin resistance in A2780cis and W1CR, and auranofin in W1CR cells completely, which is neither reflected by intracellular gold levels nor cell cycle changes. Upregulated redox balance appears as a basis for resistance. W1CR cells possess higher Trx levels, whereas A2780cis cells display strong Nrf2 expression as anti-oxidative protection. Nevertheless, overcoming redox balance appears not primary mode of activity comparing cisplatin and gold(I)-compounds. pERK emerges as a critical component and thus a promising target for overcoming resistance, regulating apoptosis differently in response to either gold(I) or cisplatin in A2780 cells.

CONCLUSION

These data reflect the complexity of cisplatin resistance in cell models and emphasize NHC-Au(I)-complexes as prospective cytotoxic agents for further investigations in that respect.

Potentiation of Cisplatin Cytotoxicity in Resistant Ovarian Cancer SKOV3/Cisplatin Cells by Quercetin Pre-Treatment

Previously, we demonstrated that the overexpression of antioxidant enzymes (SOD-1, SOD-2, Gpx-1, CAT, and HO-1), transcription factor NFE2L2, and the signaling pathway (PI3K/Akt/mTOR) contribute to the cisplatin resistance of SKOV-3/CDDP ovarian cells, and treatment with quercetin (QU) alone has been shown to inhibit the expression of these genes. The aim of this study was to expand the previous data by examining the efficiency of reversing cisplatin resistance and investigating the underlying mechanism of pre-treatment with QU followed by cisplatin in the same ovarian cancer cells. The pre-incubation of SKOV-3/CDDP cells with quercetin at an optimum dose prior to treatment with cisplatin exhibited a significant cytotoxic effect. Furthermore, a long incubation with only QU for 48 h caused cell cycle arrest at the G1/S phase, while a QU pre-treatment induced sub-G1 phase cell accumulation (apoptosis) in a time-dependent manner. An in-depth study of the mechanism of the actions revealed that QU pre-treatment acted as a pro-oxidant that induced ROS production by inhibiting the thioredoxin antioxidant system Trx/TrxR. Moreover, QU pre-treatment showed activation of the mitochondrial apoptotic pathway (cleaved caspases 9, 7, and 3 and cleaved PARP) through downregulation of the signaling pathway (mTOR/STAT3) in SKOV-3/CDDP cells. This study provides further new data for the mechanism by which the QU pre-treatment re-sensitizes SKOV-3/CDDP cells to cisplatin.

Scutellaria baicalensis Georgi and Their Natural Flavonoid Compounds in the Treatment of Ovarian Cancer: A Review

Ovarian cancer (OC) is one of the most common types of cancer in women with a high mortality rate, and the treatment of OC is prone to high recurrence rates and side effects. Scutellaria baicalensis (SB) is a herbal medicine with good anti-cancer activity, and several studies have shown that SB and its flavonoids have some anti-OC properties. This paper elucidated the common pathogenesis of OC, including cell proliferation and cell cycle regulation, cell invasion and metastasis, apoptosis and autophagy, drug resistance and angiogenesis. The mechanisms of SB and its flavonoids, wogonin, baicalein, baicalin, Oroxylin A, and scutellarein, in the treatment of OC, are revealed, such as wogonin inhibits proliferation, induces apoptosis, inhibits invasion and metastasis, and increases the cytotoxicity of the drug. Baicalein also inhibits vascular endothelial growth factor (VEGF) expression etc. Analyzing their advantages and disadvantages in treating OC provides a new perspective on the role of SB and its flavonoids in OC treatment. It serves as a resource for future OC research and development.

Targeting the stimulator of interferon genes (STING) in breast cancer

Breast cancer has a high occurrence rate globally and its treatment has demonstrated clinical efficacy with the use of systemic chemotherapy and immune checkpoint blockade. Insufficient cytotoxic T lymphocyte infiltration and the accumulation of immunosuppressive cells within tumours are the primary factors responsible for the inadequate clinical effectiveness of breast cancer treatment. The stimulator of interferon genes (STING) represents a pivotal protein in the innate immune response. Upon activation, STING triggers the activation and enhancement of innate and adaptive immune functions, resulting in therapeutic benefits for malignant tumours. The STING signalling pathway in breast cancer is influenced by various factors such as deoxyribonucleic acid damage response, tumour immune microenvironment, and mitochondrial function. The use of STING agonists is gaining momentum in breast cancer research. This review provides a comprehensive overview of the cyclic guanosine monophosphate-adenosine monophosphate synthase-STING pathway, its agonists, and the latest findings related to their application in breast cancer.

Differential molecular pathway expression according to chemotherapeutic response in ovarian clear cell carcinoma

OBJECTIVE

Ovarian clear cell carcinoma (OCCC) is a distinct entity from epithelial ovarian cancer. The prognosis of advanced and recurrent disease is very poor due to resistance to chemotherapeutic agents. Our aim was to explore the molecular alterations among OCCC patients with different chemotherapeutic responses and to obtain insights into potential biomarkers.

METHODS

Twenty-four OCCC patients were included in this study. The patients were divided into two groups based on the relapse time after the first-line platinum-based chemotherapy: the platinum-sensitive group (PS) and the platinum-resistant group (PR). Gene expression profiling was performed using NanoString nCounter PanCancer Pathways Panel.

RESULTS

Gene expression analysis comparing PR vs. PS identified 32 differentially expressed genes: 17 upregulated genes and 15 downregulated genes. Most of these genes are involved in the PI3K, MAPK and Cell Cycle-Apoptosis pathways. In particular, eight genes are involved in two or all three pathways.

CONCLUSION

The dysregulated genes in the PI3K, MAPK, and Cell Cycle-Apoptosis pathways identified and postulated mechanisms could help to probe biomarkers of OCCC platinum sensitivity, providing a research basis for further exploration of targeted therapy.

Syntaxin 6 Enhances the Progression of Epithelial Ovarian Cancer by Promoting Cancer Cell Proliferation

OBJECTIVES

The aim of this study is to evaluate the expression of syntaxin 6 (STX6) in epithelial ovarian cancer (EOC) and assess the effects of STX6 on the prognosis of patient.

METHODS

Using information from the Kaplan-Meier Plotter database, the effects of STX6 expression on overall survival (OS) and progression-free survival (PFS) in ovarian cancer patients were examined. The clinical information of 147 patients with epithelial ovarian cancer was evaluated, and immunohistochemical staining was used to identify STX6 expression in postoperative tumor specimens, and the affection of STX6 expression on patient prognosis was assessed. In addition, the expression of STX6 in tumor tissue, peritoneal metastases (PM) derived from 13 patients with epithelial ovarian cancer and 6 normal ovarian specimens was detected by PCR and Western blot. In order to investigate how STX6 affects the proliferation of tumor cells, STX6 was also over expressed and knock down in ovarian cancer cell lines. Then colony formation assay was used to explore the effect of STX6 regulating on cell proliferation.

RESULTS

Kaplan-Meier Plotter enrollment data analysis revealed that patients with overexpressed STX6 had substantially worse OS and PFS than individuals with low STX6 expression. Retrospective study revealed a significant (P<0.05) correlation between the STX6 expression and tumor classifications, tumor stage, peritoneal carcinomatosis index (PCI), and PFS survival of patients. Western blot and PCR findings for fresh samples showed that STX6 was overexpressed in both primary lesions and PM nodules of OC. SKOV3 cell proliferation was shown to be dramatically reduced by STX6 knockdown and promoted by STX6 overexpression, according to the in vitro experiments.

CONCLUSION

STX6 may increase the progression of epithelial OC by encouraging the proliferation of cancer cells, indicating that STX6 was a viable therapeutic target of epithelial OC.

Sustained delivery of PARP inhibitor Talazoparib for the treatment of BRCA-deficient ovarian cancer

Background

Ovarian cancer has long been known to be the deadliest cancer associated with the female reproductive system. More than 15% of ovarian cancer patients have a defective BRCA-mediated homologous recombination repair pathway that can be therapeutically targeted with PARP inhibitors (PARPi), such as Talazoparib (TLZ). The expansion of TLZ clinical approval beyond breast cancer has been hindered due to the highly potent systemic side effects resembling chemotherapeutics. Here we report the development of a novel TLZ-loaded PLGA implant (InCeT-TLZ) that sustainedly releases TLZ directly into the peritoneal (i.p.) cavity to treat patient-mimicking BRCA-mutated metastatic ovarian cancer (mOC).

Methods

InCeT-TLZ was fabricated by dissolving TLZ and PLGA in chloroform, followed by extrusion and evaporation. Drug loading and release were confirmed by HPLC. The in vivo therapeutic efficacy of InCeT-TLZ was carried out in a murine Brca2^-/-p53^R172H/-Pten^-/- genetically engineered peritoneally mOC model. Mice with tumors were divided into four groups: PBS i.p. injection, empty implant i.p. implantation, TLZ i.p. injection, and InCeT-TLZ i.p. implantation. Body weight was recorded three times weekly as an indicator of treatment tolerance and efficacy. Mice were sacrificed when the body weight increased by 50% of the initial weight.

Results

Biodegradable InCeT-TLZ administered intraperitoneally releases 66 μg of TLZ over 25 days. In vivo experimentation shows doubled survival in the InCeT-TLZ treated group compared to control, and no significant signs of toxicity were visible histologically in the surrounding peritoneal organs, indicating that the sustained and local delivery of TLZ greatly maximized therapeutic efficacy and minimized severe clinical side effects. The treated animals eventually developed resistance to PARPi therapy and were sacrificed. To explore treatments to overcome resistance, in vitro studies with TLZ sensitive and resistant ascites-derived murine cell lines were carried out and demonstrated that ATR inhibitor and PI3K inhibitor could be used in combination with the InCeT-TLZ to overcome acquired PARPi resistance.

Conclusion

Compared to intraperitoneal PARPi injection, the InCeT-TLZ better inhibits tumor growth, delays the ascites formation, and prolongs the overall survival of treated mice, which could be a promising therapy option that benefits thousands of women diagnosed with ovarian cancer.

Synthesis, Characterization and Biological Investigation of the Platinum(IV) Tolfenamato Prodrug–Resolving Cisplatin-Resistance in Ovarian Carcinoma Cell Lines

The research on the anticancer potential of platinum(IV) complexes represents one strategy to circumvent the deficits of approved platinum(II) drugs. Regarding the role of inflammation during carcinogenesis, the effects of non-steroidal anti-inflammatory drug (NSAID) ligands on the cytotoxicity of platinum(IV) complexes is of special interest. The synthesis of cisplatin- and oxaliplatin-based platinum(IV) complexes with four different NSAID ligands is presented in this work. Nine platinum(IV) complexes were synthesized and characterized by use of nuclear magnetic resonance (NMR) spectroscopy (1H, 13C, 195Pt, 19F), high-resolution mass spectrometry, and elemental analysis. The cytotoxic activity of eight compounds was evaluated for two isogenic pairs of cisplatin-sensitive and -resistant ovarian carcinoma cell lines. Platinum(IV) fenamato complexes with a cisplatin core showed especially high in vitro cytotoxicity against the tested cell lines. The most promising complex, 7, was further analyzed for its stability in different buffer solutions and behavior in cell cycle and cell death experiments. Compound 7 induces a strong cytostatic effect and cell line-dependent early apoptotic or late necrotic cell death processes. Gene expression analysis suggests that compound 7 acts through a stress-response pathway integrating p21, CHOP, and ATF3.

Targeting the NRF2/KEAP1 pathway in cervical and endometrial cancers

Cervical and endometrial cancers are among the most dangerous gynaecological malignancies, with high fatality and recurrence rates due to frequent diagnosis at an advanced stage and chemoresistance onset. The NRF2/KEAP1 signalling pathway plays an important role in protecting cells against oxidative damage due to increased reactive oxygen species (ROS) levels. NRF2, activated by ROS, induces the expression of antioxidant enzymes such as heme oxygenase, catalase, glutathione peroxidase and superoxide dismutase which neutralize ROS, protecting cells against oxidative stress damage. However, activation of NRF2/KEAP1 signalling in cancer cells results in chemoresistance, inactivating drug-mediated oxidative stress and protecting cancer cells from drug-induced cell death. We review the literature on the role of the NRF2/KEAP1 pathway in cervical and endometrial cancers, with a focus on the expression of its components and downstream genes. We also examine the role of the NRF2/KEAP1 pathway in chemotherapy resistance and how this pathway can be modulated by natural and synthetic modulators.

Identification of EMP1 as a critical gene for cisplatin resistance in ovarian cancer by using integrated bioinformatics analysis

BACKGROUND

Cisplatin resistance is among the main reasons for the poor prognosis of ovarian cancer (OC) patients. Until now, effective biomarkers for predicting cisplatin resistance in OC and specific drugs for reversing this resistance are lacking. This study identified the critical gene associated with cisplatin resistance in OC and provided a potential target for overcoming this resistance.

METHODS

Differentially expressed genes between cisplatin-resistant and -sensitive OCs were identified by screening public datasets. Survival analysis was conducted to screen prognosis-related DEGs. CIBERSORT, ESTIMATE, and immune checkpoint genes were used to assess the association between EMP1 expression and tumor microenvironment features. CTRP and GDSC databases were employed to analyze the correlation between EMP1 expression and cisplatin resistance. Furthermore, immunohistochemistry, qPCR, Western blotting, siRNA interference, and the CCK8 assay were performed to verify the role of EMP1 in cisplatin resistance in vitro. Finally, xenograft mouse models were generated to further confirm the role of EMP1 in cisplatin resistance in vivo.

RESULTS

EMP1 was identified as a critical gene associated with cisplatin resistance in OC. According to bioinformatics analyses, increased EMP1 expression was linked to higher stromal/ESTIMATE scores as well as greater ICG expression levels. The in vitro experiments showed that EMP1 was highly expressed in cisplatin-resistant OC tissues and cells, and silencing this EMP1 expression enhanced OC cell sensitivity to cisplatin. Finally, in vivo experiments confirmed that EMP1 promotes tumor growth and cisplatin resistance.

CONCLUSIONS

EMP1 can act as a predictive biomarker for cisplatin resistance in OC and as a potential therapeutic target.

Therapy-Induced Stromal Senescence Promoting Aggressiveness of Prostate and Ovarian Cancer

Cancer progression is supported by the cross-talk between tumor cells and the surrounding stroma. In this context, senescent cells in the tumor microenvironment contribute to the development of a pro-inflammatory milieu and the acquisition of aggressive traits by cancer cells. Anticancer treatments induce cellular senescence (therapy-induced senescence, TIS) in both tumor and non-cancerous cells, contributing to many detrimental side effects of therapies. Thus, we focused on the effects of chemotherapy on the stromal compartment of prostate and ovarian cancer. We demonstrated that anticancer chemotherapeutics, regardless of their specific mechanism of action, promote a senescent phenotype in stromal fibroblasts, resulting in metabolic alterations and secretion of paracrine factors, sustaining the invasive and clonogenic potential of both prostate and ovarian cancer cells. The clearance of senescent stromal cells, through senolytic drug treatment, reverts the malignant phenotype of tumor cells. The clinical relevance of TIS was validated in ovarian and prostate cancer patients, highlighting increased accumulation of lipofuscin aggregates, a marker of the senescent phenotype, in the stromal compartment of tissues from chemotherapy-treated patients. These data provide new insights into the potential efficacy of combining traditional anticancer strategies with innovative senotherapy to potentiate anticancer treatments and overcome the adverse effects of chemotherapy.

A trans-Pt(II) hedgehog pathway inhibitor complex with cytotoxicity towards breast cancer stem cells and triple negative breast cancer cells

The first example of a Pt complex of GANT61, a hedgehog (Hh) pathway inhibitor is reported. Reaction of cis-[Pt(II)Cl₂(dmso)₂] with one equivalent of 4-pyridine carboxaldehyde (4-PCA, control ligand) or one equivalent of GANT61 (Hh pathway inhibitor) in acetone at rt for 30 minutes afforded trans-[Pt(II)Cl₂(dmso)(4-PCA)] (1) and trans-[Pt(II)Cl₂(dmso)(GANT61)] (2) respectively, where 4-PCA and GANT61 are N-donor ligands. The structures of 1 and 2 were fully characterised by elemental analysis, ¹H NMR, ¹³C NMR and IR spectroscopy and X-ray crystallography. 1 and 2 undergo isomerisation from trans- to cis-in solution and therefore the biological activity of 2 is also associated with the cis-configuration. The in vitro cytotoxicity data show that 2 is a potent inhibitor of the growth of breast CSC-depleted HMLER and breast CSC-enriched HMLER-shEcad cells. Furthermore 2 markedly reduced the size and viability and significantly reduced the number of CSC-enriched HMLER-shEcad mammospheres formed. 2 also induced apoptosis with low micromolar IC₅₀ values against two triple negative breast cancer lines, MDA-MB-231 (MDA231) and BT549. 2, which possesses the Hh pathway inhibitor GANT61 as an N donor ligand exhibits far superior anti-CSC activity including in the CSC-enriched mammosphere model and activity against TNBC cells as compared to its control analogue, the trans-Pt(II) 4-PCA complex 1. The trans-Pt GANT61 complex 2 has also been shown to cause DNA damage and inhibit the Hh pathway at the level of GLI.

New progress of glutamine metabolism in the occurrence, development, and treatment of ovarian cancer from mechanism to clinic

Glutamine is a non-essential amino acid that can be synthesized by cells. It plays a vital role in the growth and proliferation of mammalian cells cultured in vitro. In the process of tumor cell proliferation, glutamine not only contributes to protein synthesis but also serves as the primary nitrogen donor for purine and pyrimidine synthesis. Studies have shown that glutamine-addicted tumor cells depend on glutamine for survival and reprogram glutamine utilization through the Krebs cycle. Potential therapeutic approaches for ovarian cancer including blocking the entry of glutamine into the tricarboxylic acid cycle in highly aggressive ovarian cancer cells or inhibiting glutamine synthesis in less aggressive ovarian cancer cells. Glutamine metabolism is associated with poor prognosis of ovarian cancer. Combining platinum-based chemotherapy with inhibition of glutamine metabolic pathways may be a new strategy for treating ovarian cancer, especially drug-resistant ovarian cancer. This article reviews the role of glutamine metabolism in the biological behaviors of ovarian cancer cells, such as proliferation, invasion, and drug resistance. Its potential use as a new target or biomarker for ovarian cancer diagnosis, treatment, and the prognosis is investigated.

Immunogenic cell death-related gene landscape predicts the overall survival and immune infiltration status of ovarian cancer

Background: Ovarian cancer (OC) is the most troubling malignant tumor of the female reproductive system. It has a low early diagnosis rate and a high tumor recurrence rate after treatment. Immunogenic cell death (ICD) is a unique form of regulated cell death that can activate the adaptive immune system through the release of DAMPs and cytokines in immunocompromised hosts and establish long-term immunologic memory. Therefore, this study aims to explore the prognostic value and underlying mechanisms of ICD-related genes in OC on the basis of characteristics. Methods: The gene expression profiles and related clinical information of OC were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. ICD-related genes were collected from the Genecards database. ICD-related prognostic genes were obtained by intersecting ICD-related genes with the OC prognostic-related genes that were analyzed in the TCGA database. Functional enrichment, genetic mutation, and immune infiltration correlation analyses were further performed to identify underlying mechanisms. Subsequently, we developed a TCGA cohort-based prognostic risk model that included a nine-gene signature through univariate and multivariate Cox regression and LASSO regression analyses. Meanwhile, external validation was performed on two sets of GEO cohorts and the TCGA training cohort for three other common tumors in women. In addition, a nomogram was established by integrating clinicopathological features and ICD-related gene signature to predict survival probability. Finally, functional enrichment and immune infiltration analyses were performed on the two risk subgroups. Results: By utilizing nine genes (ERBB2, RB1, CCR7, CD38, IFNB1, ANXA2, CXCL9, SLC9A1, and SLAMF7), we constructed an ICD-related prognostic signature. Subsequently, patients were subdivided into high- and low-risk subgroups in accordance with the median value of the risk score. In multivariate Cox regression analyses, risk score was an independent prognostic factor (hazard ratio = 2.783; p < 0.01). In the TCGA training cohort and the two GEO validation cohorts, patients with high-risk scores had worse prognosis than those with low-risk scores (p < 0.05). The time-dependent receiver operating characteristic curve further validated the prognostic power of the gene signature. Finally, gene set enrichment analysis indicated that multiple oncological pathways were significantly enriched in the high-risk subgroup. By contrast, the low-risk subgroup was strongly related to the immune-related signaling pathways. Immune infiltration analysis further illustrated that most immune cells showed higher levels of infiltration in the low-risk subgroup than in the high-risk subgroup. Conclusion: We constructed a novel ICD-related gene model for forecasting the prognosis and immune infiltration status of patients with OC. In the future, new ICD-related genes may provide novel potential targets for the therapeutic intervention of OC.

Role of RAS signaling in ovarian cancer

The RAS family of proteins is among the most frequently mutated genes in human malignancies. In ovarian cancer (OC), the most lethal gynecological malignancy, RAS, especially KRAS mutational status at codons 12, 13, and 61, ranges from 6-65% spanning different histo-types. Normally RAS regulates several signaling pathways involved in a myriad of cellular signaling cascades mediating numerous cellular processes like cell proliferation, differentiation, invasion, and death. Aberrant activation of RAS leads to uncontrolled induction of several downstream signaling pathways such as RAF-1/MAPK (mitogen-activated protein kinase), PI3K phosphoinositide-3 kinase (PI3K)/AKT, RalGEFs, Rac/Rho, BRAF (v-Raf murine sarcoma viral oncogene homolog B), MEK1 (mitogen-activated protein kinase kinase 1), ERK (extracellular signal-regulated kinase), PKB (protein kinase B) and PKC (protein kinase C) involved in cell proliferation as well as maintenance pathways thereby driving tumorigenesis and cancer cell propagation. KRAS mutation is also known to be a biomarker for poor outcome and chemoresistance in OC. As a malignancy with several histotypes showing varying histopathological characteristics, we focus on reviewing recent literature showcasing the involvement of oncogenic RAS in mediating carcinogenesis and chemoresistance in OC and its subtypes.

Metformin Improves Ovarian Cancer Sensitivity to Paclitaxel and Platinum-Based Drugs: A Review of In Vitro Findings

Ovarian cancer is one of the most dangerous gynecologic cancers worldwide, showing a high fatality rate and recurrence due to diagnosis at an advanced stage of the disease and the occurrence of chemoresistance, which weakens the therapeutic effects of the chemotherapeutic treatments. In fact, although paclitaxel and platinum-based drugs (carboplatin or cisplatin) are widely used alone or in combination to treat ovarian cancer, the occurrence of chemoresistance significantly reduces the effects of these drugs. Metformin is a hypoglycemic agent that is commonly used for the treatment of type 2 diabetes mellitus and non-alcoholic fatty liver disease. However, this drug also shows anti-tumor activity, reducing cancer risk and chemoresistance. This review analyzes the current literature regarding the role of metformin in ovarian cancer and investigates what is currently known about its effects in reducing paclitaxel and platinum resistance to restore sensitivity to these drugs.

Crosstalk between Ca2+ Signaling and Cancer Stemness: The Link to Cisplatin Resistance

In the fight against cancer, therapeutic strategies using cisplatin are severely limited by the appearance of a resistant phenotype. While cisplatin is usually efficient at the beginning of the treatment, several patients endure resistance to this agent and face relapse. One of the reasons for this resistant phenotype is the emergence of a cell subpopulation known as cancer stem cells (CSCs). Due to their quiescent phenotype and self-renewal abilities, these cells have recently been recognized as a crucial field of investigation in cancer and treatment resistance. Changes in intracellular calcium (Ca²⁺) through Ca²⁺ channel activity are essential for many cellular processes such as proliferation, migration, differentiation, and survival in various cell types. It is now proved that altered Ca²⁺ signaling is a hallmark of cancer, and several Ca²⁺ channels have been linked to CSC functions and therapy resistance. Moreover, cisplatin was shown to interfere with Ca²⁺ homeostasis; thus, it is considered likely that cisplatin-induced aberrant Ca²⁺ signaling is linked to CSCs biology and, therefore, therapy failure. The molecular signature defining the resistant phenotype varies between tumors, and the number of resistance mechanisms activated in response to a range of pressures dictates the global degree of cisplatin resistance. However, if we can understand the molecular mechanisms linking Ca²⁺ to cisplatin-induced resistance and CSC behaviors, alternative and novel therapeutic strategies could be considered. In this review, we examine how cisplatin interferes with Ca²⁺ homeostasis in tumor cells. We also summarize how cisplatin induces CSC markers in cancer. Finally, we highlight the role of Ca²⁺ in cancer stemness and focus on how they are involved in cisplatin-induced resistance through the increase of cancer stem cell populations and via specific pathways.

Unveiling the mechanism of action of nature-inspired anti-cancer compounds using a multi-omics approach

The 2020 global cancer registry has ranked breast cancer (BCa) as the most commonly diagnosed type of cancer and the most common cause of cancer-related deaths in women worldwide. Increasing resistance and significant side effects continue to limit the efficacy of anti-BCa drugs, hence the need to identify new drug targets and to develop novel compounds to overcome these limitations. Nature-inspired anti-cancer compounds are becoming increasingly popular since they often provide a relatively safe and effective alternative. In this study, we employed multi-omics techniques to gain insights into the relevant mechanism of action of two recently identified new nature-inspired anti-cancer compounds (SIMR3066 and SIMR3058). Discovery proteomics analysis combined with LC-MS/MS-based untargeted metabolomics analysis was performed on compound-treated vs DMSO-treated (control) MCF-7 cells. Downstream protein functional enrichment analysis showed that most of the responsive proteins were functionally associated with antigen processing and neutrophil degranulation, RNA catabolism and protein folding as well as cytoplasmic vesicle lumen and mitochondrial matrix formation. Consistent with the proteomics findings, metabolomic pathway analysis suggested that the differentially abundant compounds indicated altered metabolic pathways such as glycolysis, the Krebs cycle and oxidative phosphorylation. Furthermore, metabolomics-based enriched-for-action pathway analysis showed that the two compounds associate with mercaptopurine, thioguanine and azathioprine related pathways. Lastly, integrated proteomics and metabolomics analysis revealed that treatment of BCa with SIMR3066 disrupts several signaling pathways including p53-mediated apoptosis and the circadian entertainment pathway. Overall, the multi-omics approach we used in this study indicated that it is a powerful tool in probing the mechanism of action of lead drug candidates. SIGNIFICANCE: In this study we adopted a multi-omics (proteomics and metabolomics) strategy to learn more about the molecular mechanisms of action of nature-inspired potential anticancer drugs. Following treatment with SIMR3066 or SIMR3058, the integration of these multi-omics data sets revealed which biological pathways are altered in BCa cells. This study demonstrates that combining proteomics with metabolomics is a powerful method to investigate the mechanism of action of potential anticancer lead drug candidates.

Redox Mechanisms in Cisplatin Resistance of Cancer Cells: The Twofold Role of Gamma-Glutamyltransferase 1 (GGT1)

Cisplatin (CDDP) is currently employed for the treatment of several solid tumors, but cellular heterogeneity and the onset of drug resistance dictate that suitable biomarkers of CDDP sensitivity are established. Studies on triple-negative breast cancer (TNBC) have recently confirmed the involvement of gamma-glutamyltransferase 1 (GGT1), whose enzyme activity expressed at the cell surface favors the cellular resupply of antioxidant glutathione (GSH) thus offering cancer cells protection against the prooxidant effects of CDDP. However, an additional well-established mechanism depends on GGT1-mediated matabolism of extracellular GSH. It was in fact shown that glycyl-cysteine – the dipeptide originated by GGT1-mediated GSH metabolism at the cell surface – can promptly form adducts with exogenous CDDP, thus hindering its access to the cell, interactions with DNA and overall cytotoxicity. Both mechanisms: mainainance of intracellular GSH levels plus extracellular CDDP detoxication are likely concurring to determine GGT1-dependent CDDP resistance.

Role of NRF2 in Ovarian Cancer

Among gynaecologic malignancies, ovarian cancer is one of the most dangerous, with a high fatality rate and relapse due to the occurrence of chemoresistance. Many researchers demonstrated that oxidative stress is involved in tumour occurrence, growth and development. Nuclear factor erythroid 2-related factor 2 (NRF2) is an important transcription factor, playing an important role in protecting against oxidative damage. Increased levels of Reactive Oxygen Species (ROS) activate NRF2 signalling, inducing the expression of antioxidant enzymes, such as haem oxygenase (HO-1), catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), that protect cells against oxidative stress. However, NRF2 activation in cancer cells is responsible for the development of chemoresistance, inactivating drug-mediated oxidative stress that normally leads to cancer cells’ death. In this review, we report evidence from the literature describing the effect of NRF2 on ovarian cancer, with a focus on its function in drug resistance, NRF2 natural and synthetic modulators and its protective function in normal ovarian preservation.