Desferal regulates hCtr1 and transferrin receptor expression through Sp1 and exhibits synergistic cytotoxicity with platinum drugs in oxaliplatin-resistant human cervical cancer cells in vitro and in vivo

Targeting ferroptosis for precision medicine in cervical cancer

Cervical cancer (CC) is a prevalent malignant tumor in the female reproductive system, with rising incidence rates among younger women posing a significant public health challenge. Human papillomavirus (HPV) infection is the primary cause, driving carcinogenesis by promoting abnormal proliferation of tumor cells. Ferroptosis is a form of regulated necrosis that is caused by an iron-dependent accumulation of lipid peroxides with rupture of the plasma membrane. Targeting ferroptosis-related molecules and pathways can selectively induce cervical cancer cell death, while alterations in the expression of ferroptosis-related genes provide promising biomarkers for prognostic assessment. Advances in research on biomarkers and molecular targets are improving predictions of therapeutic outcomes, overcoming drug resistance, and optimizing immunotherapy strategies, thereby opening new avenues for precision medicine. This review focuses on the molecular mechanisms underlying ferroptosis in cervical cancer, discusses its potential applications in early diagnosis and prognosis evaluation, and summarizes the latest advancements in targeted therapy, aiming to provide a novel perspective for the clinical management of cervical cancer.

The recent advancements of ferroptosis of gynecological cancer

Ovarian, endometrial, and cervical cancer are the most common types of gynecologic tumor in women. Surgery, combined with radiotherapy and chemotherapy, is commonly used to treat these tumors. Unfortunately, difficulties in early diagnosis and acquired drug resistance have resulted in poor outcomes for most patients. Ferroptosis is a form of regulated cell death that depends on iron and is characterized by iron accumulation, reactive oxygen species production, and lipid peroxidation. The strong association between ferroptosis and many diseases, especially tumor diseases, has been confirmed by numerous studies. Many studies have demonstrated that ferroptosis is involved in initiating, progressing and metastasizing gynecologic tumors. This review summarizes the pathogenesis of ferroptosis and its association with the development, treatment, and prognosis of gynecologic tumors, and further explore the potential utility of ferroptosis in treating gynecologic tumors.

HTRA1 interacts with SLC7A11 to modulate colorectal cancer chemosensitivity by inhibiting ferroptosis

Chemotherapy is an important therapuetic strategy for colorectal cancer (CRC), but chemoresistance severely affects its efficacy, and the underlying mechanism has not been fully elucidated. Increasing evidence suggests that lipid peroxidation imbalance-mediated ferroptosis is closely associated with chemoresistance. Hence, targeting ferroptosis pathways or modulating the tolerance to oxidative stress might be an effective strategy to reverse tumor chemoresistance. HtrA serine protease 1 (HTRA1) was screened out as a CRC progression- and chemoresistance-related gene. It is highly expressed in CRC cells and negatively correlated with the prognosis of CRC patients. Gain- and loss-of-function analyses demonstrated a stimulatory role of HTRA1 on the proliferation of CRC cells. The enrichment analysis of HTRA1-interacting proteins indicated the involvement of ferroptosis in the HTRA1-mediated chemoresistance. Moreover, electron microscope analysis, as well as the ROS and MDA levels in CRC cells also confirmed the effect of HTRA1 on ferroptosis. We also verified that HTRA1 could interact with SLC7A11 through its Kazal structural domain and up-regulate the expression of SLC7A11, which in turn inhibited the ferroptosis and leaded to the chemoresistance of CRC cells to 5-FU/L-OHP. Hence, we propose that HTRA1 may be a potential therapeutic target and a prognostic indicator in CRC.

In vitro siRNA-mediated GPX4 and AKT1 silencing in oxaliplatin resistance cancer cells induces ferroptosis and apoptosis

Oxaliplatin is a member of platinum-based chemotherapy drugs frequently used in colorectal cancer (CRC). However, resistance to oxaliplatin causes tumor progression and metastasis. Akt1 and Gpx4 are essential regulator genes of apoptosis and ferroptosis pathways. Inhibition of these genes might eradicate oxaliplatin resistance in resistant CRC cells. We compared two cell death strategies to reverse drug resistance in Caco-2 and HT-29 oxaliplatin-resistant cell lines. We used the AKT1-specific siRNA to induce apoptosis. Also, GPX4-specific siRNA and FIN56 were utilized to generate ferroptosis. The effect of these treatments was assessed by reactive oxygen species (ROS) formation, cell viability, and protein expression level assays. Besides, the expression of GPX4, CoQ10, and NRF2 was assessed in both cell lines after treatments. Correctly measuring the expression of these responsible genes and proteins confirms the occurrence of different types of cell death. In addition, the ability of Akt1/ GPX4 siRNA in resensitizing HT-29 and Caco-2 oxaliplatin resistance cells was evaluated. Our finding showed that the upregulation of GPX4/siRNA caused a reduction in GPX4 and CoQ10 expressions in both cell lines. However, the expression level of NRF2 showed the same level in our cell lines, so we observed a downregulation of NRF2 in resistant CRC cell lines. Cell viability assay indicated that induction of ferroptosis by GPX4/siRNA or FIN56 and apoptosis by Akt1/siRNA in resistant cell lines could reverse the oxaliplatin resistance. We concluded that downregulation of Akt1 or Gpx4 could increase the efficacy of oxaliplatin to overcome the resistance compared to FIN56.

Immunogenic cell death in cancer immunotherapy

Cancer immunotherapy has been acknowledged as a new paradigm for cancer treatment, with notable therapeutic effects on certain cancer types. Despite their significant potential, clinical studies over the past decade have revealed that cancer immunotherapy has low response rates in the majority of solid tumors. One of the key causes for poor responses is known to be the relatively low immunogenicity of solid tumors. Because most solid tumors are immune desert 'cold tumors' with antitumor immunity blocked from the onset of innate immunity, combination therapies that combine validated T-based therapies with approaches that can increase tumor-immunogenicity are being considered as relevant therapeutic options. This review paper focuses on immunogenic cell death (ICD) as a way of enhancing immunogenicity in tumor tissues. We will thoroughly review how ICDs such as necroptosis, pyroptosis, and ferroptosis can improve anti-tumor immunity and outline clinical trials targeting ICD. Finally, we will discuss the potential of ICD inducers. as an adjuvant for cancer immunotherapy.[BMB Reports 2023; 56(5): 275-286].

Immunogenic cell death in cancer immunotherapy

Cancer immunotherapy has been acknowledged as a new paradigm for cancer treatment, with notable therapeutic effects on certain cancer types. Despite their significant potential, clinical studies over the past decade have revealed that cancer immunotherapy has low response rates in the majority of solid tumors. One of the key causes for poor responses is known to be the relatively low immunogenicity of solid tumors. Because most solid tumors are immune desert 'cold tumors' with antitumor immunity blocked from the onset of innate immunity, combination therapies that combine validated T-based therapies with approaches that can increase tumor-immunogenicity are being considered as relevant therapeutic options. This review paper focuses on immunogenic cell death (ICD) as a way of enhancing immunogenicity in tumor tissues. We will thoroughly review how ICDs such as necroptosis, pyroptosis, and ferroptosis can improve anti-tumor immunity and outline clinical trials targeting ICD. Finally, we will discuss the potential of ICD inducers. as an adjuvant for cancer immunotherapy.[BMB Reports 2023; 56(5): 275-286].

Iron Deficiency Increases Phosphorylation of SP1 to Upregulate SPNS2 Expression in Hepatocellular Carcinoma

The sphingosine-1-phosphate (S1P) transporter spinster homolog 2 (SPNS2) promotes tumor progression by modulating tumor immunity and enhancing tumor cells migration and invasion. Previously we found that iron deficiency in hepatocellular carcinoma upregulated SPNS2 expression to increase tumor metastasis. The present study aimed to identify the underlying mechanism of SPNS2 upregulation. Since the mRNA of SPNS2 was significantly increased, we used a transcription factor activity microarray to find the transcription factor responsible for this. The results showed that iron deprivation in hepatoma cells increased the transcriptional activities of 14 transcription factors while only 2 were decreased. Among these, 3 transcription factors, HIF1α, SP1, and YY1, were predicted to bind with the transcription promoter region of SPNS2. But only HIF1α and SP1 transcriptional activities on SPNS2 were increased by iron deficiency, and the increase of SP1 transcriptional activity was stronger than HIF1α. The protein level of HIF1α was increased by iron deficiency, while SP1 was not changed at the protein level but the phosphorylation level was increased. The inhibitor of HIF1α, PX478, and the inhibitor of SP1, Mithramycin A, reversed the increased mRNA and protein expressions of SPNS2 by iron deficiency, with a more significant effect by Mithramycin A. These results provided a comprehensive view of changes in transcriptional activities by iron deficiency and identified that SP1 was the main regulator of iron deficiency-inducing SPNS2 expression in hepatoma cells.

Ferroptosis: Mechanism and potential applications in cervical cancer

Ferroptosis is a distinct form of cell death mechanism different from the traditional ones. Ferroptosis is characterized biochemically by lipid peroxidation, iron accumulation, and glutathione deficiency. It has already demonstrated significant promise in antitumor therapy. Cervical cancer (CC) progression is closely linked to iron regulation and oxidative stress. Existing research has investigated the role of ferroptosis in CC. Ferroptosis could open up a new avenue of research for treating CC. This review will describe the factors and pathways and the research basis of ferroptosis, which is closely related to CC. Furthermore, the review may provide potential future directions for CC research, and we believe that more studies concerning the therapeutic implications of ferroptosis in CC will come to notice.

The critical role of ferritinophagy in human disease

Ferritinophagy is a type of autophagy mediated by nuclear receptor activator 4 (NCOA4), which plays a role in inducing ferroptosis by regulating iron homeostasis and producing reactive oxygen species in cells. Under physiological conditions, ferritinophagy maintains the stability of intracellular iron by regulating the release of free iron. Studies have demonstrated that ferritinophagy is necessary to induce ferroptosis; however, under pathological conditions, excessive ferritinophagy results in the release of free iron in large quantities, which leads to lipid peroxidation and iron-dependent cell death, known as ferroptosis. Ferritinophagy has become an area of interest in recent years. We here in review the mechanism of ferritinophagy and its association with ferroptosis and various diseases to provide a reference for future clinical and scientific studies.

Ferroptosis and Tumor Drug Resistance: Current Status and Major Challenges

Ferroptosis is a novel type of regulated cell death, whose unique metabolic characteristics are commonly used to evaluate the conditions of various diseases especially in tumors. Accumulating evidence supports that ferroptosis can regulate tumor development, metastasis, and therapeutic responses. Considering to the important role of chemotherapy in tumor treatment, drug resistance has become the most serious challenge. Revealing the molecular mechanism of ferroptosis is expected to solve tumor drug resistance and find new therapies to treat cancers. In this review, we discuss the relationship between ferroptosis and tumor drug resistance, summarize the abnormal ferroptosis in tissues of different cancer types and current research progress and challenges in overcoming treatment resistance, and explore the concept of targeting ferroptosis to improve tumor treatment outcomes.

An iron chelation-based combinatorial anticancer therapy comprising deferoxamine and a lactate excretion inhibitor inhibits the proliferation of cancer cells

BACKGROUND

Although iron chelation has garnered attention as a novel therapeutic strategy for cancer, higher levels of efficacy need to be achieved. In the present study, we examined the combinatorial effect of deferoxamine (DFO), an iron chelator, and α-cyano-4-hydroxy cinnamate (CHC), a suppressor of lactate excretion, on the proliferation of cancer cell lines.

METHODS

We established a deferoxamine (DFO)-resistant cell line by culturing HeLa cells in media containing increasing concentrations of DFO. Metabolome and gene expression analyses were performed on these cells. Synergistic effect of the drugs on the cells was determined using an in vitro proliferation assay, and the combination index was estimated.

RESULTS

DFO-resistant HeLa cells exhibited enhanced glycolysis, salvage cycle, and de novo nucleic acid synthesis and reduced mitochondrial metabolism. As DFO triggered a metabolic shift toward glycolysis and increased lactate production in cells, we treated the cancer cell lines with a combination of CHC and DFO. A synergistic effect of DFO and CHC was observed in HeLa cells; however, the same was not observed in the human liver cancer cell line Huh7. We hypothesized that the efficacy of the combination therapy in cancer cells depends on the degree of increase in lactate concentration upon DFO treatment.

CONCLUSION

Combination therapy involving administration of DFO and CHC is effective in cancer cells wherein DFO treatment results in an elevation in lactate levels. Our findings illustrate that the DFO-induced enhanced glycolysis provides specific targets for developing an efficient anticancer combinatorial therapy involving DFO. These findings will be beneficial for the development of novel cancer chemotherapeutics.

Effects of trans-(±)-kusunokinin on chemosensitive and chemoresistant ovarian cancer cells

Ovarian cancer ranks eighth in cancer incidence and mortality among women worldwide. Cisplatin-based chemotherapy is commonly used for patients with ovarian cancer. However, the clinical efficacy of cisplatin is limited due to the occurrence of adverse side effects and development of cancer chemoresistance during treatment. Trans-(±)-kusunokinin has been previously reported to inhibit cell proliferation and induce cell apoptosis in various cancer cell types, including breast, colon and cholangiocarcinoma. However, the potential effects of (±)-kusunokinin on ovarian cancer remains unknown. In the present study, chemosensitive ovarian cancer cell line A2780 and chemoresistant ovarian cancer cell lines A2780cis, SKOV-3 and OVCAR-3 were treated with trans-(±)-kusunokinin to investigate its potential effects. MTT, colony formation, apoptosis and multi-caspase assays were used to determine cytotoxicity, the ability of single cells to form colonies, induction of apoptosis and multi-caspase activity, respectively. Moreover, western blot analysis was performed to determine the proteins level of topoisomerase II, cyclin D1, CDK1, Bax and p53-upregulated modulator of apoptosis (PUMA). The results demonstrated that trans-(±)-kusunokinin exhibited the strongest cytotoxicity against A2780cis cells with an IC50 value of 3.4 µM whilst also reducing the colony formation of A2780 and A2780cis cells. Trans-(±)-kusunokinin also induced the cells to undergo apoptosis and increased multi-caspase activity in A2780 and A2780cis cells. This compound significantly downregulated topoisomerase II, cyclin D1 and CDK1 expression, but upregulated Bax and PUMA expression in both A2780 and A2780cis cells. In conclusion, trans-(±)-kusunokinin suppressed ovarian cancer cells through the inhibition of colony formation, cell proliferation and the induction of apoptosis. This pure compound could be a potential targeted therapy for ovarian cancer treatment in the future. However, studies in an animal model and clinical trial need to be performed to support the efficacy and safety of this new treatment.

Exploring the clinical value of tumor microenvironment in platinum-resistant ovarian cancer

Platinum resistance in epithelial ovarian cancer (OvCa) is rising at an alarming rate, with recurrence of chemo-resistant high grade serous OvCa (HGSC) in roughly 75 % of all patients. Additionally, HGSC has an abysmal five-year survival rate, standing at 39 % and 17 % for FIGO stages III and IV, respectively. Herein we review the crucial cellular interactions between HGSC cells and the cellular and non-cellular components of the unique peritoneal tumor microenvironment (TME). We highlight the role of the extracellular matrix (ECM), ascitic fluid as well as the mesothelial cells, tumor associated macrophages, neutrophils, adipocytes and fibroblasts in platinum-resistance. Moreover, we underscore the importance of other immune-cell players in conferring resistance, including natural killer cells, myeloid-derived suppressive cells (MDSCs) and T-regulatory cells. We show the clinical relevance of the key platinum-resistant markers and their correlation with the major pathways perturbed in OvCa. In parallel, we discuss the effect of immunotherapies in re-sensitizing platinum-resistant patients to platinum-based drugs. Through detailed analysis of platinum-resistance in HGSC, we hope to advance the development of more effective therapy options for this aggressive disease.

Integrated analysis identifies TfR1 as a prognostic biomarker which correlates with immune infiltration in breast cancer

Breast cancer (BC) is the most common malignancy with high morbidity and mortality in females worldwide. Emerging evidence indicates that transferrin receptor 1 (TfR1) plays vital roles in regulating cellular iron import. However, the distinct role of TfR1 in BC remains elusive. TfR1 expression was investigated using the TCGA, GEO, TIMER, UALCAN and Oncomine databases. The prognostic potential of TfR1 was evaluated by Kaplan-Meier (KM) plotter and univariate and multivariate Cox regression analyses. Moreover, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA) were used to explore the molecular mechanism of TfR1. The potential link between TfR1 expression and infiltrating abundances of immune cells was examined through the TIMER and CIBERSORT algorithm. The expression of TfR1 was dramatically upregulated in BC tissues. Increased TfR1 expression and decreased methylation levels of TfR1 were strongly correlated with multiple clinicopathological parameters. Elevated TfR1 expression was associated with a poor survival rate in BC patients. The nomogram model further confirmed that TfR1 could act as an independent prognostic biomarker in BC. The results of GO, KEGG and GSEA revealed that TfR1 was closely correlated with multiple signaling pathways and immune responses. Additionally, TfR1 was positively associated with the infiltration abundances of six major immune cells, including CD4+ T cells, CD8+ T cells, B cells, neutrophils, macrophages, and dendritic cells in BC. Interestingly, TfR1 influenced prognosis partially through immune infiltration. These comprehensive bioinformatics analyses suggest that TfR1 is a new independent prognostic biomarker and a potential target for immunotherapy in BC.

Curcumin-cisplatin chemotherapy: A novel strategy in promoting chemotherapy efficacy and reducing side effects

The efficacy of chemotherapy in cancer therapy is limited due to resistance, treatment selectivity, and severe adverse effects. Immunotherapy, chemotherapy, targeted therapy, radiation, and surgery are the most common therapeutic strategies for treatment, with chemotherapy being the most successful. Nonetheless, these treatments exhibit poor effectiveness due to toxicity and resistance. Therefore, combination therapies of natural products may be used as an effective and novel strategy to overcome such barriers. Cisplatin is a platinum-based chemotherapy agent, and when administered alone, it can lead to severe adverse effects and resistance mechanism resulting in therapeutic failure. Curcumin is a polyphenolic compound extracted from turmeric (Curcuma longa) exhibiting anticancer potential with minimal adverse effects. The combination therapy of curcumin and cisplatin is a novel strategy to mitigate/attenuate cisplatin-related adverse effects and improve the barrier of resistance reducing unwanted effects. However, there are uncertainties on the efficacy of curcumin, and more in depth and high-quality studies are needed. This review aims to explain the adverse effects related to individual cisplatin delivery, the positive outcome of individual curcumin delivery, and the combination therapy of curcumin and cisplatin from nano platform as a novel strategy for cancer therapy.

Targeting iron metabolism in cancer therapy

Iron is a critical component of many cellular functions including DNA replication and repair, and it is essential for cell vitality. As an essential element, iron is critical for maintaining human health. However, excess iron can be highly toxic, resulting in oxidative DNA damage. Many studies have observed significant associations between iron and cancer, and the association appears to be more than just coincidental. The chief characteristic of cancers, hyper-proliferation, makes them even more dependent on iron than normal cells. Cancer therapeutics are becoming as diverse as the disease itself. Targeting iron metabolism in cancer cells is an emerging, formidable field of therapeutics. It is a strategy that is highly diverse with regard to specific targets and the various ways to reach them. This review will discuss the importance of iron metabolism in cancer and highlight the ways in which it is being explored as the medicine of tomorrow.

Iron Metabolism in the Tumor Microenvironment: Contributions of Innate Immune Cells

Cells of the innate immune system are a major component of the tumor microenvironment. They play complex and multifaceted roles in the regulation of cancer initiation, growth, metastasis and responses to therapeutics. Innate immune cells like neutrophils and macrophages are recruited to cancerous tissues by chemotactic molecules released by cancer cells and cancer-associated stromal cells. Once they reach the tumor, they can be instructed by a network of proteins, nucleic acids and metabolites to exert protumoral or antitumoral functions. Altered iron metabolism is a feature of cancer. Epidemiological studies suggest that increased presence of iron and/or iron binding proteins is associated with increased risks of cancer development. It has been shown that iron metabolism is involved in shaping the immune landscapes in inflammatory/infectious diseases and cancer-associated inflammation. In this article, we will dissect the contribution of macrophages and neutrophils to dysregulated iron metabolism in malignant cells and its impact on cancer growth and metastasis. The mechanisms involved in regulating the actions of macrophages and neutrophils will also be discussed. Moreover, we will examine the effects of iron metabolism on the phenotypes of innate immune cells. Both iron chelating and overloading agents are being explored in cancer treatment. This review highlights alternative strategies for management of iron content in cancer cells by targeting the iron donation and modulation properties of macrophages and neutrophils in the tumor microenvironment.

New Insights into Mechanisms of Cisplatin Resistance: From Tumor Cell to Microenvironment

Although cisplatin has been a pivotal chemotherapy drug in treating patients with various types of cancer for decades, drug resistance has been a major clinical impediment. In general, cisplatin exerts cytotoxic effects in tumor cells mainly through the generation of DNA-platinum adducts and subsequent DNA damage response. Accordingly, considerable effort has been devoted to clarify the resistance mechanisms inside tumor cells, such as decreased drug accumulation, enhanced detoxification activity, promotion of DNA repair capacity, and inactivated cell death signaling. However, recent advances in high-throughput techniques, cell culture platforms, animal models, and analytic methods have also demonstrated that the tumor microenvironment plays a key role in the development of cisplatin resistance. Recent clinical successes in combination treatments with cisplatin and novel agents targeting components in the tumor microenvironment, such as angiogenesis and immune cells, have also supported the therapeutic value of these components in cisplatin resistance. In this review, we summarize resistance mechanisms with respect to a single tumor cell and crucial components in the tumor microenvironment, particularly focusing on favorable results from clinical studies. By compiling emerging evidence from preclinical and clinical studies, this review may provide insights into the development of a novel approach to overcome cisplatin resistance.

IGF1R predicts better survival in high-grade serous epithelial ovarian cancer patients and correlates with hCtr1 levels

Aim: To evaluate the potential of IGF1R as a prognostic marker for high-grade serous ovarian cancer (HGSOC) patients. Patients & methods: The expression levels of IGF1R and drug transporters (ABCB1, hCtr1) were measured longitudinally in chemo-naive and chemo-treated tumor samples from 19 HGSOC patients, and their correlation with the clinical outcome was examined. Results: IGF1R expression was significantly upregulated in treated tumor samples, which positively correlated with hCtr1 levels. Patients with metastatic tumors with IGF1R expression higher than median showed better overall survival (median not reached) and disease-free survival (26.7 months) than those with less than median expression (overall survival: 27.5 months [p = 0.029]; disease-free survival: 11.9 months [p = 0.014]). Conclusion: IGF1R prognosticates prolonged survival in HGSOC patients, possibly due to its positive correlation with hCtr1.

Ionophores: Potential Use as Anticancer Drugs and Chemosensitizers

Ion homeostasis is extremely important for the survival of both normal as well as neoplastic cells. The altered ion homeostasis found in cancer cells prompted the investigation of several ionophores as potential anticancer agents. Few ionophores, such as Salinomycin, Nigericin and Obatoclax, have demonstrated potent anticancer activities against cancer stem-like cells that are considered highly resistant to chemotherapy and responsible for tumor relapse. The preclinical success of these compounds in in vitro and in vivo models have not been translated into clinical trials. At present, phase I/II clinical trials demonstrated limited benefit of Obatoclax alone or in combination with other anticancer drugs. However, future development in targeted drug delivery may be useful to improve the efficacy of these compounds. Alternatively, these compounds may be used as leading molecules for the development of less toxic derivatives.

Modulating Chemosensitivity of Tumors to Platinum-Based Antitumor Drugs by Transcriptional Regulation of Copper Homeostasis

Platinum (Pt)-based antitumor agents have been effective in treating many human malignancies. Drug importing, intracellular shuffling, and exporting—carried out by the high-affinity copper (Cu) transporter (hCtr1), Cu chaperone (Ato x1), and Cu exporters (ATP7A and ATP7B), respectively—cumulatively contribute to the chemosensitivity of Pt drugs including cisplatin and carboplatin, but not oxaliplatin. This entire system can also handle Pt drugs via interactions between Pt and the thiol-containing amino acid residues in these proteins; the interactions are strongly influenced by cellular redox regulators such as glutathione. hCtr1 expression is induced by acute Cu deprivation, and the induction is regulated by the transcription factor specific protein 1 (Sp1) which by itself is also regulated by Cu concentration variations. Copper displaces zinc (Zn) coordination at the zinc finger (ZF) domains of Sp1 and inactivates its DNA binding, whereas Cu deprivation enhances Sp1-DNA interactions and increases Sp1 expression, which in turn upregulates hCtr1. Because of the shared transport system, chemosensitivity of Pt drugs can be modulated by targeting Cu transporters. A Cu-lowering agent (trientine) in combination with a Pt drug (carboplatin) has been used in clinical studies for overcoming Pt-resistance. Future research should aim at further developing effective Pt drug retention strategies for improving the treatment efficacy.

Rapid diagnosis of cisplatin-sensitive and resistant cervical squamous cell carcinomas by reverse transcription loop-mediated isothermal amplification

Cisplatin is a widely used platinum anticancer drug in cervical cancer chemotherapy; however, its use is limited by the development of drug resistance, which is often rationalized via effects on cellular uptake. Human copper transporter 1 (hCTR1) was proven as crucial regulator for cellular platinum uptake in cancer cells and improving effect of cisplatin treatment. Thus, methods to detect expression of hCTR1 in patients in biopsy specimens with certain rapidity and accuracy are essential to evaluate platinum drug sensitivity and perform further individualized treatment. In this study, a total of 46 normal cervical and primary cervical squamous cell carcinoma tissues were collected and tested by reverse transcription loop-mediated isothermal amplification (RT-LAMP) analysis targeted hCTR1 mRNA. Sensitivity and specificity of RT-LAMP results were calculated and compared to immunohistochemical (IHC) examination. Overexpression of hCTR1 RNA was detected in 12 samples using RT-LAMP within 45 minutes reaction, which indicated positivity with cisplatin resistance. This new technique is suggested to be alternative for rapid diagnosis of cisplatin sensitive patients whose hCTR1 is prevalent.

Nrf2 induces cisplatin resistance via suppressing the iron export related gene SLC40A1 in ovarian cancer cells

Induction of Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) has been demonstrated to be involved in cisplatin resistance in ovarian cancer. Solute carrier family 40 member 1 (SLC40A1) is an iron exporter, which possesses many putative Nrf2 binding sites. Here we hypothesize that it may be a possible downstream gene of Nrf2. Elevated level of Nrf2 and reduced level of SLC40A1 were found in cisplatin–resistant ovarian cancer cells as compared with cisplatin-sensitive ovarian cancer cells. Exogenous knockdown of Nrf2 leaded to increased expression of SLC40A1. While overexpression of Nrf2 resulted in decreased expression of SLC40A1. Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assay revealed that Nrf2 inhibited the transcription of SLC40A1. Overexpression of SLC40A1 was able to reverse cisplatin resistance induced by Nrf2, while knockdown of SLC40A1 restored cisplatin resistance and increased iron concentration. Desferal, an iron chelator, was found to overcome cisplatin resistance through iron deprivation. Its function was boosted when combined with brusatol, an Nrf2 inhibitor. Taken together, this study first demonstrated that Nrf2 could transcriptionally suppress the expression of SLC40A1. Iron overload induced by SLC40A1 resulted in cisplatin resistance in ovarian cancer. Targeting iron metabolism may be a new therapeutic strategy to reverse drug resistance in ovarian cancer treatment.