Noscapine sensitizes chemoresistant ovarian cancer cells to cisplatin through inhibition of HIF-1α

Advance in vasculogenic mimicry in ovarian cancer (Review)

Ovarian cancer (OC) is a common and highly prevalent malignant tumor in women, associated with a high mortality rate, easy recurrence and easy metastasis, which is predominantly at an advanced stage when detected in patients. This renders the cancer more difficult to treat, and consequently it is also associated with a low survival rate, being the malignancy with the highest mortality rate among the various gynecological tumors. As an important factor affecting the development and metastasis of OC, understanding the underlying mechanism(s) through which it is formed and developed is crucial in terms of its treatment. At present, the therapeutic methods of angiogenic mimicry for OC remain in the preliminary stages of exploration and have not been applied in actual clinical practice. In the present review, various signaling pathways and factors affecting angiogenic mimicry in OC were described, and the chemical synthetic drugs, natural compound extracts, small-molecule protein antibodies and their associated targets, and so on, that target angiogenic mimicry in the treatment of OC, were discussed. The purpose of this review was to provide new research ideas and potential theoretical support for the discovery of novel therapeutic targets for OC that may be applied in the clinic, with the aim of effectively reducing its metastasis and recurrence rates.

Novel cancer treatment paradigm targeting hypoxia-induced factor in conjunction with current therapies to overcome resistance

Chemotherapy, radiotherapy, targeted therapy, and immunotherapy are established cancer treatment modalities that are widely used due to their demonstrated efficacy against tumors and favorable safety profiles or tolerability. Nevertheless, treatment resistance continues to be one of the most pressing unsolved conundrums in cancer treatment. Hypoxia-inducible factors (HIFs) are a family of transcription factors that regulate cellular responses to hypoxia by activating genes involved in various adaptations, including erythropoiesis, glucose metabolism, angiogenesis, cell proliferation, and apoptosis. Despite this critical function, overexpression of HIFs has been observed in numerous cancers, leading to resistance to therapy and disease progression. In recent years, much effort has been poured into developing innovative cancer treatments that target the HIF pathway. Combining HIF inhibitors with current cancer therapies to increase anti-tumor activity and diminish treatment resistance is one strategy for combating therapeutic resistance. This review focuses on how HIF inhibitors could be applied in conjunction with current cancer treatments, including those now being evaluated in clinical trials, to usher in a new era of cancer therapy.

Extracellular ATP promotes breast cancer chemoresistance via HIF-1α signaling

We have previously demonstrated that extracellular adenosine 5'-triphosphate (ATP) promotes breast cancer cell chemoresistance. However, the underlying mechanism remains unclear. Using a cDNA microarray, we demonstrated that extracellular ATP can stimulate hypoxia-inducible factor (HIF) signaling. In this study, we report that hypoxia-inducible factor 1α (HIF-1α) was upregulated after ATP treatment and mediated the ATP-driven chemoresistance process. We aimed to investigate the mechanisms and identify potential clinically relevant targets that are involved. Using mass spectrometry, we found that aldolase A (ALDOA) interacts with HIF-1α and increases HIF-1α expression. We then demonstrated that STAT3-ALDOA mediates ATP-HIF-1α signaling and upregulates the HIF-1 target genes adrenomedullin (ADM) and phosphoinositide-dependent kinase-1 (PDK1). Moreover, we show that PI3K/AKT acts upstream of HIF-1α in ATP signaling and contributes to chemoresistance in breast cancer cells. In addition, HIF-1α-knockdown or treatment with direct HIF inhibitors combined with the ATP hydrolase apyrase in MDA-MB-231 cells induced enhanced drug sensitivity in nude BALB/c mice. We then used in vitro spheroid formation assays to demonstrate the significance of ATP-HIF-1α in mediating chemoresistance. Furthermore, considering that indirect HIF inhibitors are effective in clinical cancer therapy, we treated tumor-bearing BALB/c mice with STAT3 and PI3K/AKT inhibitors and found that the dual-targeting strategy sensitized breast cancer to cisplatin. Finally, using breast cancer tissue microarrays, we found that ATP-HIF-1α signaling is associated with cancer progression, poor prognosis, and resistance to chemotherapy. Taken together, we suggest that HIF-1α signaling is vital in ATP-driven chemoresistance and may serve as a potential target for breast cancer therapies.

Noscapine, an Emerging Medication for Different Diseases: A Mechanistic Review

Noscapine is a benzylisoquinoline alkaloid isolated from poppy extract, used as an antitussive since the 1950s, and has no addictive or euphoric effects. Various studies have shown that noscapine has excellent anti-inflammatory effects and potentiates the antioxidant defences by inhibiting nitric oxide (NO) metabolites and reactive oxygen species (ROS) levels and increasing total glutathione (GSH). Furthermore, noscapine has indicated antiangiogenic and antimetastatic effects. Noscapine induces apoptosis in many cancerous cell types and provides favourable antitumour activities and inhibitory cell proliferation in solid tumours, even drug-resistant strains, via mitochondrial pathways. Moreover, this compound attenuates the dynamic properties of microtubules and arrests the cell cycle in the G2/M phase. Noscapine can reduce endothelial cell migration in the brain by inhibiting endothelial cell activator interleukin 8 (IL-8). In fact, this study aimed to elaborate on the possible mechanisms of noscapine against different disorders.

Biological and pharmacological activities of noscapine: Focusing on its receptors and mechanisms

Noscapine has been mentioned as one of the effective drugs with potential therapeutic applications. With few side effects and amazing capabilities, noscapine can be considered different from other opioids-like structure compounds. Since 1930, extensive studies have been conducted in the field of pharmacological treatments from against malaria to control cough and cancer treatment. Furthermore, recent studies have shown that noscapine and some analogues, like 9-bromonoscapine, amino noscapine, and 9-nitronoscapine, can be used to treat polycystic ovaries syndrome, stroke, and other diseases. Given the numerous results presented in this field and the role of different receptors in the therapeutic effects of noscapine, we aimed to review the properties, therapeutic effects, and the role of receptors in the treatment of noscapine.

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

Simple Summary

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

Abstract

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

The Chemosensitizing Role of Metformin in Anti-Cancer Therapy

Chemoresistance, which leads to the failure of chemotherapy and further tumor recurrence, presents the largest hurdle for the success of anti-cancer therapy. In recent years, metformin, a widely used first-line antidiabetic drug, has attracted increasing attention for its anti-cancer effects. A growing body of evidence indicates that metformin can sensitize tumor responses to different chemotherapeutic drugs, such as hormone modulating drugs, anti-metabolite drugs, antibiotics, and DNA-damaging drugs via selective targeting of Cancer Stem Cells (CSCs), improving the hypoxic microenvironment, and by suppressing tumor metastasis and inflammation. In addition, metformin may regulate metabolic programming, induce apoptosis, reverse Epithelial to Mesenchymal Transition (EMT), and Multidrug Resistance (MDR). In this review, we summarize the chemosensitization effects of metformin and focus primarily on its molecular mechanisms in enhancing the sensitivity of multiple chemotherapeutic drugs, through targeting of mTOR, ERK/P70S6K, NF-κB/HIF-1 α, and Mitogen- Activated Protein Kinase (MAPK) signaling pathways, as well as by down-regulating the expression of CSC genes and Pyruvate Kinase isoenzyme M2 (PKM2). Through a comprehensive understanding of the molecular mechanisms of chemosensitization provided in this review, the rationale for the use of metformin in clinical combination medications can be more systematically and thoroughly explored for wider adoption against numerous cancer types.>.

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

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

Effect of arsenic trioxide on cervical cancer and its mechanisms

Cervical cancer is one of the most common types of gynecological tumor, and thus identifying complementary or substitute treatment methods to treat cervical cancer is important. The present study aimed to evaluate the effect of arsenic trioxide (ATO), a traditional Chinese medicine, on cervical cancer cells and its underlying mechanism. MTT, colony formation and Transwell assays were performed to investigate the effects of different concentrations of ATO on cell proliferation and invasion, respectively. Western blotting and reverse transcription-quantitative PCR were applied to measure hypoxia-inducible factor-1α expression (HIF-1α) expression following ATO treatment. Finally, the effects of HIF-1α knockdown on cervical cancer cell proliferation, apoptosis and invasion were evaluated. The results demonstrated that ATO could inhibit cell proliferation and invasion. Moreover, ATO could induce reactive oxygen species production in a time- and dose-dependent manner. ATO could also promote the apoptosis of cervical cancer cells via HIF-1α. Therefore, the present study may provide a theoretical basis for identifying effective molecular targets for the prevention and treatment of cervical cancer.

A Combinational Approach Towards Treatment of Breast Cancer: an Analysis of Noscapine-Loaded Polymeric Nanoparticles and Doxorubicin

Our aim in this study was to clarify the combination anticancer effect of Noscapine (Nos) loaded in a polymeric nanocarrier with Doxorubicin (Dox) on breast cancer cells. Nanoprecipitation method was used to prepare methoxy polyethylene glycol (mPEG), poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) containing Nos. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to characterize the prepared Nos NPs. The anticancer activity of Nos NPs alone and in combination with Dox was assessed on 4T1 breast cancer cell line and in mice model. Spherical-shaped Nos NPs were prepared, with size of 101 ± 4.80 nm and zeta potential of - 15.40 ± 1 mV. Fourier transform infrared (FTIR) spectroscopy results demonstrated that Nos chemical structure was kept stable during preparation process. However, differential scanning calorimetric (DSC) thermogram proved that crystalline state of Nos changed to amorphous state in Nos NPs. The entrapment efficacy % (EE%) and drug loading % (DL%) of Nos NPs were about 87.20 ± 3.50% and 12.50 ± 2.30%, respectively. Synergistic anticancer effects of Nos both in free form (in hydrochloride form, Nos HCl) and Nos NPs form with Dox hydrochloride (Dox HCl) were observed on 4T1 cells. Combination of Nos NPs and Dox HCl inhibited tumor growth (68.50%) in mice more efficiently than Nos NPs (55.10%) and Dox HCl (32%) alone. Immunohistochemical (IHC) analysis of the tumor tissues confirmed antiangiogenic effect of Nos NPs. The findings highlighted efficacy of Nos NPs alone and in combination with Dox HCl on breast cancer tumors.

XPA: DNA Repair Protein of Significant Clinical Importance

The nucleotide excision repair (NER) pathway is activated in response to a broad spectrum of DNA lesions, including bulky lesions induced by platinum-based chemotherapeutic agents. Expression levels of NER factors and resistance to chemotherapy has been examined with some suggestion that NER plays a role in tumour resistance; however, there is a great degree of variability in these studies. Nevertheless, recent clinical studies have suggested Xeroderma Pigmentosum group A (XPA) protein, a key regulator of the NER pathway that is essential for the repair of DNA damage induced by platinum-based chemotherapeutics, as a potential prognostic and predictive biomarker for response to treatment. XPA functions in damage verification step in NER, as well as a molecular scaffold to assemble other NER core factors around the DNA damage site, mediated by protein–protein interactions. In this review, we focus on the interacting partners and mechanisms of regulation of the XPA protein. We summarize clinical oncology data related to this DNA repair factor, particularly its relationship with treatment outcome, and examine the potential of XPA as a target for small molecule inhibitors.

Mechanisms of Vasculogenic Mimicry in Ovarian Cancer

Solid tumors carry out the formation of new vessels providing blood supply for growth, tumor maintenance, and metastasis. Several processes take place during tumor vascularization. In angiogenesis, new vessels are derived from endothelial cells of pre-existing vessels; while in vasculogenesis, new vessels are formed de novo from endothelial progenitor cells, creating an abnormal, immature, and disorganized vascular network. Moreover, highly aggressive tumor cells form structures similar to vessels, providing a pathway for perfusion; this process is named vasculogenic mimicry (VM), where vessel-like channels mimic the function of vessels and transport plasma and blood cells. VM is developed by numerous types of aggressive tumors, including ovarian carcinoma which is the second most common cause of death among gynecological cancers. VM has been associated with poor patient outcome and survival in ovarian cancer, although the involved mechanisms are still under investigation. Several signaling molecules have an important role in VM in ovarian cancer, by regulating the expression of genes related to vascular, embryogenic, and hypoxic signaling pathways. In this review, we provide an overview of the current knowledge of the signaling molecules involved in the promotion and regulation of VM in ovarian cancer. The clinical implications and the potential benefit of identification and targeting of VM related molecules for ovarian cancer treatment are also discussed.

LncRNA ANRIL affects the sensitivity of ovarian cancer to cisplatin via regulation of let-7a/HMGA2 axis

This paper tried to explore ANRIL expression in ovarian cancer and how it affects cisplatin-sensitivity of ovarian cancer cells via regulation of let-7a/high-mobility group protein A2 (HMGA2) axis. qRT-PCR was used to detect ANRIL and let-7a levels in ovarian cancer tissues and cell lines (SKOV3 and SKOV3/DDP). Then cells were randomly assigned into Blank, negative control siRNA, ANRIL siRNA, let-7a inhibitor, and ANRIL siRNA+let-7a-inhibitor groups. CCK-8 assay was applied for assessing cell viability of cells treated with different concentrations of cisplatin. Flow cytometry was employed to test cell apoptosis rate. qRT-PCR and Western blot were performed for related molecules detection. Nude mice transplanted with SKOV3/DDP cells were used to confirm the effects of ANRIL siRNA on the cisplatin-sensitivity. Ovarian cancer tissues and cisplatin-resistant cells had increased ANRIL expression and decreased let-7a expression, and those patients with higher clinical stage and pathological grade showed higher ANRIL and lower let-7a. Dual-luciferase reporter-gene assay confirmed the targeting relationship between ANRIL and let-7a, and between let-7a and HMGA2. The cell viability and cisplatin IC₅₀ were decreased in ANRIL siRNA group exposed to different concentrations of cisplatin, with enhanced apoptosis, as well as elevated let-7a and declined HMGA2, which would be reversed by let-7a inhibitor. Meanwhile, ANRIL down-regulation enhanced the inhibitory effect of cisplatin on tumor growth of nude mice and reduced tumor weight. Silencing ANRIL expression reduced HMGA2 expression to promote the apoptosis and improve cisplatin-sensitivity of ovarian cancer cells via up-regulating let-7a expression.

Antiangiogenic Effect of Alkaloids

Alkaloids are among the natural phytochemicals contained in functional foods and nutraceuticals and have been suggested for the prevention and/or management of oxidative stress and inflammation-mediated diseases. In this review, we aimed to describe the effects of alkaloids in angiogenesis, the process playing a crucial role in tumor growth and invasion, whereby new vessels form. Antiangiogenic compounds including herbal ingredients, nonherbal alkaloids, and microRNAs can be used for the control and treatment of cancers. Several lines of evidence indicate that alkaloid-rich plants have several interesting features that effectively inhibit angiogenesis. In this review, we present valuable data on commonly used alkaloid substances as potential angiogenic inhibitors. Different herbal and nonherbal ingredients, introduced as antiangiogenesis agents, and their role in angiogenesis-dependent diseases are reviewed. Studies indicate that angiogenesis suppression is exerted through several mechanisms; however, further investigations are required to elucidate their precise molecular and cellular mechanisms, as well as potential side effects.

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

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

miR-205-5p Mediated Downregulation of PTEN Contributes to Cisplatin Resistance in C13K Human Ovarian Cancer Cells

Cisplatin resistance is a major cause of treatment failure in advanced ovarian cancer. The limited evidence shows the paradoxical regulation of miR-205 on chemotherapy resistance in cancer. Herein, we found that miR-205-5p was enormously increased in cisplatin-resistant C13K ovarian cancer cells compared with its cisplatin-sensitive OV2008 parental cells using miRNA microarrays, which was further verified by quantitative PCR. Furthermore, we confirmed that inhibition of miR-205-5p upregulated PTEN and subsequently attenuated its downstream target p-AKT, which inversed C13K cells from cisplatin resistance to sensitivity. Our data suggest that miR-205-5p contributes to cisplatin resistance in C13K ovarian cancer cells may via targeting PTEN/AKT pathway.

Bitter taste receptors are expressed in human epithelial ovarian and prostate cancers cells and noscapine stimulation impacts cell survival

Bitter taste receptors (Tas2Rs) are a subfamily of G-protein coupled receptors expressed not only in the oral cavity but also in several extra-oral tissues and disease states. Several natural bitter compounds from plants, such as bitter melon extract and noscapine, have displayed anti-cancer effects against various cancer types. In this study, we examined the prevalence of Tas2R subtype expression in several epithelial ovarian or prostate cancer cell lines, and the functionality of Tas2R14 was determined. qPCR analysis of five TAS2Rs demonstrated that mRNA expression often varies greatly in cancer cells in comparison to normal tissue. Using receptor-specific siRNAs, we also demonstrated that noscapine stimulation of ovarian cancer cells increased apoptosis in ovarian cancer cells in a receptor-dependent, but ROS-independent manner. This study furthers our understanding of the function of Tas2Rs in ovarian cancer by demonstrating that their activation has an impact on cell survival.

Melatonin Synergizes the Chemotherapeutic Effect of Cisplatin in Ovarian Cancer Cells Independently of MT1 Melatonin Receptors

BACKGROUND/AIM

Melatonin (MLT), through the interaction with membrane melatonin receptors MT1, can improve the effectiveness of cytostatic agents, including cisplatin (CP). The aim of this study was to examine the synergistic effect of MLT and CP in three cell lines: IOSE 364, SK-OV-3 and OVCAR-3, as well as to assess the role of MT1 receptors in this mechanism.

MATERIALS AND METHODS

Using the SRB assay we investigated the effect of different concentrations of CP and MLT on cell viability. Tests, using luzindole - MT1 inhibitor, allowed us to assess the potential involvement of MT1 in the mechanism of MLT action.

RESULTS

MLT at certain concentrations demonstrated a synergistic effect in combination with CP. The addition of luzindole did not affect the action of MLT in combination with CP.

CONCLUSION

In summary, the synergistic effect of MLT with CP seems to be independent of membrane MT1 receptors.

Reversal of drug-resistance by noscapine chemo-sensitization in docetaxel resistant triple negative breast cancer

Multidrug resistance (MDR) is a major impediment to cancer treatment. Here, for the first time, we investigated the chemo-sensitizing effect of Noscapine (Nos) at low concentrations in conjunction with docetaxel (DTX) to overcome drug resistance of triple negative breast cancer (TNBC). In vitro experiments showed that Nos significantly inhibited proliferation of TNBC wild type (p < 0.01) and drug resistant (p < 0.05) TNBC cells. Nos followed by DTX treatment notably increased the cell viability (~1.3 fold) markedly (p < 0.05) in 3D models compared to conventional 2D systems. In vivo oral administration of Nos (100 mg/kg) followed by intravenous DTX (5 mg/kg) liposome treatment revealed regression of xenograft tumors in both wild type (p < 0.001) and drug-resistant (p < 0.05) xenografts. In wild type xenografts, combination of Nos plus DTX group showed 5.49 and 3.25 fold reduction in tumor volume compared to Nos and DTX alone groups, respectively. In drug-resistant xenografts, tumor volume was decreased 2.33 and 1.41 fold in xenografts treated with Nos plus DTX significantly (p < 0.05) compared to Nos and DTX alone respectively and downregulated the expression of anti-apoptotic factors and multidrug resistance proteins. Collectively, chemo-sensitizing effect of Nos followed by DTX regime provide a promising chemotherapeutic strategy and its significant role for the treatment of drug-resistant TNBC.

Phytomedicine-Modulating oxidative stress and the tumor microenvironment for cancer therapy

In spite of the current advances and achievements in systems biology and translational medicinal research, the current strategies for cancer therapy, such as radiotherapy, targeted therapy, immunotherapy and chemotherapy remain palliative or unsatisfactory due to tumor metastasis or recurrence after surgery/therapy, drug resistance, adverse side effects, and so on. Oxidative stress (OS) plays a critical role in chronic/acute inflammation, carcinogenesis, tumor progression, and tumor invasion/metastasis which is also attributed to the dynamic and complex properties and activities in the tumor microenvironment (TME). Re-educating or reprogramming tumor-associated stromal or immune cells in the TME provides an approach for restoring immune surveillance impaired by disease in cancer patients to increase overall survival and reduce drug resistance. Herbal medicines or plant-derived natural products have historically been a major source of anti-cancer drugs. Delving into the lore of herbal medicine may uncover new leads for anti-cancer drugs. Phytomedicines have been widely documented to directly or indirectly target multiple signaling pathways and networks in cancer cells. A combination of anti-cancer drugs and polypharmacological plant-derived extracts or compounds may offer a significant advantage in sensitizing the efficacy of monotherapy and overcoming drug-induced resistance in cancer patients. This review introduces several phytochemicals and phytoextracts derived from medicinal plants or dietary vegetables that have been studied for their efficacy in preclinical cancer models. We address the underlying modes of action of induction of OS and deregulation of TME-associated stromal cells, mediators and signaling pathways, and reference the related clinical investigations that look at the single or combination use of phytochemicals and phytoextracts to sensitize anti-cancer drug effects and/or overcome drug resistance.

Metformin sensitizes the response of oral squamous cell carcinoma to cisplatin treatment through inhibition of NF-κB/HIF-1α signal axis

Resistance towards chemotherapy is a common complication in treatment of oral cancers, which leads to treatment failure and poor outcome. In recent years, a growing body of evidence has shown that tumour hypoxia significantly contributes to chemoresistance. Metformin, a widely used oral hypoglycaemic drug, can reportedly potentiate the efficacy of chemotherapeutic drugs in various cancers; however, the underlying mechanisms are intricate and have not been fully understood. In this study, we explored the role of metformin in chemosensitivity of oral squamous cell carcinoma cells (OSCC) to cisplatin both in vitro and in vivo, and attempted to elucidate its possible underlying mechanisms. Encouragingly, we found that metformin synergistically enhanced cisplatin cytotoxicity and reversed the chemoresistance to certain extent. This mechanism could likely be related with inhibition of the NF-κB/HIF-1α signal axis and lead to the downregulation of hypoxia-regulated genes products. Therefore, metformin could serve as a chemosensitiser for cisplatin-based regimens for OSCC, thereby providing a theoretical basis for future use in the treatment of oral cancers.

Vascular endothelial growth factor A as predictive marker for mTOR inhibition in relapsing high-grade serous ovarian cancer

Background

Development of resistance against first line drug therapy including cisplatin and paclitaxel in high-grade serous ovarian cancer (HGSOC) presents a major challenge. Identifying drug candidates breaking resistance, ideally combined with predictive biomarkers allowing precision use are needed for prolonging progression free survival of ovarian cancer patients.

Modeling of molecular processes driving drug resistance in tumor tissue further combined with mechanism of action of drugs provides a strategy for identification of candidate drugs and associated predictive biomarkers.

Results

Consolidation of transcriptomics profiles and biomedical literature mining results provides 1242 proteins linked with ovarian cancer drug resistance. Integrating this set on a protein interaction network followed by graph segmentation results in a molecular process model representation of drug resistant HGSOC embedding 409 proteins in 24 molecular processes. Utilizing independent transcriptomics profiles with follow-up data on progression free survival allows deriving molecular biomarker-based classifiers for predicting recurrence under first line therapy. Biomarkers of specific relevance are identified in a molecular process encapsulating TGF-beta, mTOR, Jak-STAT and Neurotrophin signaling. Mechanism of action molecular model representations of cisplatin and paclitaxel embed the very same signaling components, and specifically proteins afflicted with the activation status of the mTOR pathway become evident, including VEGFA. Analyzing mechanism of action interference of the mTOR inhibitor sirolimus shows specific impact on the drug resistance signature imposed by cisplatin and paclitaxel, further holding evidence for a synthetic lethal interaction to paclitaxel mechanism of action involving cyclin D1.

Conclusions

Stratifying drug resistant high grade serous ovarian cancer via VEGFA, and specifically treating with mTOR inhibitors in case of activation of the pathway may allow adding precision for overcoming resistance to first line therapy.

SENP1 desensitizes hypoxic ovarian cancer cells to cisplatin by up-regulating HIF-1α

Hypoxia-inducible factor 1 alpha (HIF-1α) is closely related to chemoresistance of ovarian cancers. Although it is reported that HIF-1α can be regulated by Sentrin/SUMO-specific protease 1 (SENP1), the effects of SENP1 on HIF-1α is still controversial. In this study, we identified that SENP1 positively regulated the expression of HIF-1α by deSUMOylation and weakened the sensitivity of hypoxic ovarian cancer cells to cisplatin. These results indicate that SENP1 is a positive regulator of HIF-1α and plays a negative role in ovarian cancer chemotherapy.

The Noscapine Chronicle: A Pharmaco-Historic Biography of the Opiate Alkaloid Family and its Clinical Applications

Given its manifold potential therapeutic applications and amenability to modification, noscapine is a veritable "Renaissance drug" worthy of commemoration. Perhaps the only facet of noscapine's profile more astounding than its versatility is its virtual lack of side effects and addictive properties, which distinguishes it from other denizens of Papaver somniferum. This review intimately chronicles the rich intellectual and pharmacological history behind the noscapine family of compounds, the length of whose arms was revealed over decades of patient scholarship and experimentation. We discuss the intriguing story of this family of nontoxic alkaloids, from noscapine's purification from opium at the turn of the 19th century in Paris to the recent torrent of rationally designed analogs with tremendous anticancer potential. In between, noscapine's unique pharmacology; impact on cellular signaling pathways, the mitotic spindle, and centrosome clustering; use as an antimalarial drug and cough suppressant; and exceptional potential as a treatment for polycystic ovarian syndrome, strokes, and diverse malignancies are catalogued. Seminal experiments involving some of its more promising analogs, such as amino-noscapine, 9-nitronoscapine, 9-bromonoscapine, and reduced bromonoscapine, are also detailed. Finally, the bright future of these oftentimes even more exceptional derivatives is described, rounding out a portrait of a truly remarkable family of compounds.

The anti-tumor efficacy of 2-deoxyglucose and D-allose are enhanced with p38 inhibition in pancreatic and ovarian cell lines

PURPOSE

The anti-tumor activity of glucose analogs 2-deoxy-glucose (2-DG) and D-allose was investigated alone or in combination with p38 mitogen-activated protein kinase (MAPK) inhibitor SB202190 or platinum analogs as a strategy to pharmacologically target glycolytic tumor phenotypes.

METHODS

Hypoxia inducible factor-1 alpha (HIF-1α) protein accumulation in pancreatic cell lines treated with SB202190 alone and in combination with glucose analogs was analyzed by Western blot. HIF-1α transcriptional activity was measured in MIA PaCa-2 cells stably transfected with a hypoxia response element luciferase reporter following treatment with glucose analogs alone, and in combination with SB202190. Induction of cleaved poly(ADP-ribose) polymerase (PARP) was measured by Western blot in the MIA PaCa-2 cells. In vitro anti-proliferative activity of 2-DG and D-allose alone, or in combination with oxaliplatin (pancreatic cell lines), cisplatin (ovarian cell lines), or with SB202190 were investigated using the MTT assay.

RESULTS

SB202190 decreased HIF-1α protein accumulation and transcriptional activity. 2-DG demonstrated greater anti-proliferative activity than D-allose. Pre-treatment with SB202190 enhanced activity of both 2-DG and D-allose in MIA PaCa-2, BxPC-3, ASPC-1, and SK-OV-3 cells. The combination of D-allose and platinum agents was additive to moderately synergistic in all but the OVCAR-3 and HEY cells. SB202190 pre-treatment further enhanced activity of D-allose and 2-DG with platinum agents in most cell lines investigated.

CONCLUSIONS

SB202190 induced sensitization of tumor cells to 2-DG and D-allose may be partially mediated by inhibition of HIF-1α activity. Combining glucose analogs and p38 MAPK inhibitors with chemotherapy may be an effective approach to target glycolytic tumor phenotypes.

The fate of chemoresistance in triple negative breast cancer (TNBC)

BACKGROUND

Treatment options for women presenting with triple negative breast cancer (TNBC) are limited due to the lack of a therapeutic target and as a result, are managed with standard chemotherapy such as paclitaxel (Taxol®). Following chemotherapy, the ideal tumour response is apoptotic cell death. Post-chemotherapy, cells can maintain viability by undergoing viable cellular responses such as cellular senescence, generating secretomes which can directly enhance the malignant phenotype.

SCOPE OF REVIEW

How tumour cells retain viability in response to chemotherapeutic engagement is discussed. In addition we discuss the implications of this retained tumour cell viability in the context of the development of recurrent and metastatic TNBC disease. Current adjuvant and neo-adjuvant treatments available and the novel potential therapies that are being researched are also reviewed.

MAJOR CONCLUSIONS

Cellular senescence and cytoprotective autophagy are potential mechanisms of chemoresistance in TNBC. These two non-apoptotic outcomes in response to chemotherapy are inextricably linked and are neglected outcomes of investigation in the chemotherapeutic arena. Cellular fate assessments may therefore have the potential to predict TNBC patient outcome.

GENERAL SIGNIFICANCE

Focusing on the fact that cancer cells can bypass the desired cellular apoptotic response to chemotherapy through cellular senescence and cytoprotective autophagy will highlight the importance of targeting non-apoptotic survival pathways to enhance chemotherapeutic efficacy.

Chiral differentiation of the noscapine and hydrastine stereoisomers by electrospray ionization tandem mass spectrometry

Energy-dependent collision-induced dissociation (CID) of the dimers [2 M + Cat](+) of the noscapine and hydrastine stereoisomers was studied where Cat stands for Li(+), Na(+), K(+) and Cs(+) ions. These dimers were generated 'in situ' from the electrosprayed solution. The survival yield (SY) method was used for distinguishing the noscapine and hydrastine dimers. Significant differences were found between the characteristic collision energies (CE50, i.e. the collision energy necessary to obtain 50% fragmentation) of the homo- (R,R; S,S) and heterochiral (R,S; S,R) stereoisomers. To distinguish the enantiomer pairs L-, D-tyrosine ([M + Tyr + Cat](+)) and L-, D-lysine ([M + Lys + Cat](+)) were used as chiral selectors. Furthermore, these heterodimers [M + amino acid + Cat](+) were also applied to determine the stereoisomeric composition. It was found that the characteristic collision energy (CE50) of the noscapine and hydrastine homodimers ([2 M + Cat](+)) was inversely proportional to the ionic radius of the cations. Furthermore, the structures of the dimers [2 M + Cat](+) were studied by high level quantum chemical calculations.

BAY 87-2243, a novel inhibitor of hypoxia-induced gene activation, improves local tumor control after fractionated irradiation in a schedule-dependent manner in head and neck human xenografts

Background

The transcription factor hypoxia-inducible factor-1 (HIF-1) pathway plays an important role in tumor response to cytotoxic treatments. We investigated the effects of a novel small molecule inhibitor of mitochondrial complex I and hypoxia-induced HIF-1 activity BAY-87-2243, on tumor microenvironment and response of human squamous cell carcinoma (hSCC) to clinically relevant fractionated radiotherapy (RT) with and without concomitant chemotherapy.

Methods

When UT-SCC-5 hSCC xenografts in nude mice reached 6 mm in diameter BAY-87-2243 or carrier was administered before and/or during RT or radiochemotherapy with concomitant cisplatin (RCT). Local tumor control was evaluated 150 days after irradiation and the doses to control 50% of tumors (TCD₅₀) were compared between treatment arms. Tumors were excised at different time points during BAY-87-2243 or carrier treatment for western blot and immunohistological investigations.

Results

BAY-87-2243 markedly decreased nuclear HIF-1α expression and pimonidazole hypoxic fraction already after 3 days of drug treatment. BAY-87-2243 prior to RT significantly reduced TCD₅₀ from 123 to 100 Gy (p=0.037). Additional BAY-87-2243 application during RT did not decrease TCD₅₀. BAY-87-2243 before and during radiochemotherapy did not improve local tumor control.

Conclusions

Pronounced reduction of tumor hypoxia by application of BAY-87-2243 prior to RT improved local tumor control. The results demonstrate that radiosensitizing effect importantly depends on treatment schedule. The data support further investigations of HIF-1 pathway inhibitors for radiotherapy and of predictive tests to select patients who will benefit from this combined treatment.

Fragmentation study of noscapine derivatives under electrospray conditions

RATIONALE

Noscapine is a biologically active molecule with anticancer activity among other things. Therefore, from an analytical point of view, knowledge of the mass spectrometric properties of noscapine and its derivatives is essential. The goal of the present study is to describe the collision-induced dissociation behavior of noscapine and its seven derivatives ionized by protons and lithium and sodium ions.

METHODS

Protonated noscapines were produced using electrospray ionization (ESI) mass spectrometry (MS). For the tandem mass spectrometry (MS/MS) experiments nitrogen was used as the collision gas and the collision energies were varied in the range of 1-53 eV (in the laboratory frame).

RESULTS

The ESI-MS/MS measurements showed that the MS/MS spectra of the protonated noscapines were more informative than the lithiated and sodiated ones. Based on the MS/MS studies, the main fragmentation channels of the protonated noscapines were found to be the loss of water and the loss of a meconine moiety from the precursor ion; furthermore, methyl transfer was also observed in the MS/MS spectra.

CONCLUSIONS

The MS/MS study of the protonated noscapines gives more structural information than that of lithiated and sodiated noscapines. However, the most important fragmentation channel, which leads to the formation of the most intensive product ion in the MS/MS spectra, is independent of the ionization agent.

Epithelial transport of noscapine across cell monolayer and influence of absorption enhancers on in vitro permeation and bioavailability: implications for intestinal absorption

The purpose of this study was to investigate the permeation of Noscapine (Nos) across the Caco-2 and Madin-Darby canine kidney (MDCK) cell monolayers and to evaluate the influence of absorption enhancers on in vitro and in vivo absorption of Nos. The bidirectional transport of Nos was studied in Caco-2 and MDCK cell monolayers at pH 5.0-7.8. The effect of 0.5% w/v chitosan (CH) or Captisol (CP) on Nos permeability was investigated at pH 5.0 and 5.8. The effect of 1-5% w/v of CP on oral bioavailability of Nos (150 mg/kg) was evaluated in Sprague-Dawley rats. The effective permeability coefficients (Peff) of Nos across Caco-2 and MDCK cell monolayers was found to be in the order of pH 5.0 > 5.8 > 6.8 > 7.8. The efflux ratios of Peff < 2 demonstrated that active efflux does not limit the absorption of Nos. The use of CH or CP have shown significant (***, p < 0.001) enhancement in Peff of Nos across cell monolayer compared with the control group. The CP (1-5% w/v) based Nos formulations resulted in significant (***, p < 0.001) increase in the bioavailability of Nos compared with Nos solution. The use of CP represents viable approach for enhancing the oral bioavailability of Nos and reducing the required dose.

HIF1α regulated expression of XPA contributes to cisplatin resistance in lung cancer

Factors regulating nucleotide excision repair probably contribute to the heterogenous response of advanced stage lung cancer patients to drugs such as cisplatin. Studies to identify the genes in the nucleotide excision repair pathway most closely associated with resistance to cisplatin have not been conclusive. We hypothesized that Xeroderma pigmentosum complementation group A (XPA), because of its dual role in sensing and recruiting other DNA repair proteins to the damaged template, would be critical in defining sensitivity to cisplatin. Studies were conducted to identify factors regulating transcription of XPA, to assess its role in modulating sensitivity to cisplatin and its expression in primary lung tumors. Hypoxia-inducible factor 1 alpha (HIF1α) subunit was found to bind with strong affinity to a hypoxia response element sequence in the promoter of XPA. Modulating expression of HIF1α by small interfering RNA or cobalt chloride markedly reduced or increased transcription of XPA in lung cancer cell lines, respectively. Protein levels of XPA were strongly correlated with sensitivity to cisplatin (r = 0.88; P < 0.001) in cell lines and sensitivity could be increased by small interfering RNA depletion of XPA. Expression of XPA determined in 54 primary lung tumors was elevated on average 5.2-fold when compared with normal bronchial epithelial cells and correlated with levels of HIF1α (r = 0.58; P < 0.01). Together, these studies identify XPA as a novel target for regulation by HIF1α whose modulation could impact lung cancer therapy.

Melatonin synergistically enhances cisplatin-induced apoptosis via the dephosphorylation of ERK/p90 ribosomal S6 kinase/heat shock protein 27 in SK-OV-3 cells

To evaluate melatonin's ability to enhance ovarian cancer cells to cisplatin treatment for ovarian cancer, this study was performed. Melatonin by itself had no significant cytotoxicity against SK-OV-3 cells, while cisplatin suppressed the cell viability in a dose-dependent manner. Combined treatment with cisplatin and melatonin synergistically inhibited the viability of SK-OV-3 cells with the synergism between two drugs (1 > combination index). In contrast, melatonin revealed the protective effect against cisplatin-induced cytotoxicity in OSEN normal ovarian epithelial cells. Cotreatment with cisplatin and melatonin increased the sub-G1 DNA contents and TdT-mediated dUTP nick end-labeling (TUNEL)-positive cells compared with cisplatin control in SK-OV-3 cells, suggesting that melatonin augments cisplatin-induced apoptosis. Consistently, combined treatment of cisplatin and melatonin increased the cleavage of caspase-3 and poly-(ADP-ribose) polymerase (PARP). Importantly, melatonin synergistically inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) along with dephosphorylation of 90-kDa ribosomal S6 kinase (p90RSK) and heat shock protein 27 (HSP27) induced by cisplatin. Furthermore, melatonin remarkably blocked the expression and colocalization of p90RSK and HSP27 by combination treatment with cisplatin. Taken together, our findings demonstrate that melatonin enhances cisplatin-induced apoptosis via the inactivation of ERK/p90RSK/HSP27 cascade in SK-OV-3 cells as a potent synergist to cisplatin treatment.

Modulation of hypoxia-inducible factors (HIF) from an integrative pharmacological perspective

Oxygen homeostasis determines the activity and expression of a multitude of cellular proteins and the interplay of pathways that affect crucial cellular processes for development, physiology, and pathophysiology. Hypoxia-inducible factors (HIFs) are transcription factors that respond to changes in available oxygen in the cellular environment and drives cellular adaptation to such conditions. Selective gene expression under hypoxic conditions is the result of an exquisite regulation of HIF, from the pre-transcriptional stage of the HIF gene to the final transcriptional activity of HIF protein. We provide a dissected analysis of HIF modulation with special focus on hypoxic conditions and HIF pharmacological interventions that can guide the application of any future HIF-mediated therapy.