Broad blocking of MDR efflux pumps by acetylshikonin and acetoxyisovalerylshikonin to generate hypersensitive phenotype of malignant carcinoma cells

Valproate modulates the activity of multidrug resistance efflux pumps, as a chemoresistance factor in gastric cancer cells

BACKGROUND

Drug resistance is one of the most critical problems in gastric cancer therapy. This study was performed to investigate the valproic acid effects on the proliferation of sensitive and resistant cell lines of human gastric cancer, and to explore the mechanism of the agent on multi drug resistance and apoptosis genes.

METHODS

The cytotoxicity effect of valproic acid on the EPG85.257 and EPG85.257RDB cells was assessed by the MTT assay, and the IC50 concentration was evaluated. Apoptosis, genotoxicity, and drug resistance pump activity were evaluated using comet assay, Real-time PCR, and flow cytometry, respectively. Cell proliferation was assayed using a scratch test.

RESULTS

Dose-dependent toxicity was recorded after treatment of cells with valproic acid. Valproic acid represented a significant growth inhibition on EPG85.257 cells with IC50 values of 5.84 µM and 4.78 µM after 48 h and 72 h treatment, respectively. In contrast, the drug-resistant counterpart represented 8.7 µM and 7.02 µM IC50 values after the same treatment time. Valproic acid induced PTEN, Bcl2, P53, Bax, P21, and caspase3 expression in EPG85.257 cells, whereas p21, p53, PTEN, and ABCB1 were overexpressed in EPG5.257RDB. Valproic acid hindered cell migration in both cell lines (P < 0.01). Valproate genotoxicity was significantly higher in the parent cells than in their resistant EPG85.257RDB counterparts. Valproate led to a 62% reduction in the daunorubicin efflux of the MDR1 pump activity.

CONCLUSIONS

Valproate can affect drug resistance in gastric cancer via a unique mechanism independent of MDR1 expression.

Acetylshikonin induces necroptosis via the RIPK1/RIPK3-dependent pathway in lung cancer

Despite advances in therapeutic strategies, lung cancer remains the leading cause of cancer-related death worldwide. Acetylshikonin is a derivative of the traditional Chinese medicine Zicao and presents a variety of anticancer properties. However, the effects of acetylshikonin on lung cancer have not been fully understood yet. This study explored the mechanisms underlying acetylshikonin-induced cell death in non-small cell lung cancer (NSCLC). Treating NSCLC cells with acetylshikonin significantly reduced cell viability, as evidenced by chromatin condensation and the appearance of cell debris. Acetylshikonin has also been shown to increase cell membrane permeability and induce cell swelling, leading to an increase in the population of necrotic cells. When investigating the mechanisms underlying acetylshikonin-induced cell death, we discovered that acetylshikonin promoted oxidative stress, decreased mitochondrial membrane potential, and promoted G2/M phase arrest in lung cancer cells. The damage to NSCLC cells induced by acetylshikonin resembled results involving alterations in the cell membrane and mitochondrial morphology. Our analysis of oxidative stress revealed that acetylshikonin induced lipid oxidation and down-regulated the expression of glutathione peroxidase 4 (GPX4), which has been associated with necroptosis. We also determined that acetylshikonin induces the phosphorylation of receptor-interacting serine/threonine-protein kinase 1 (RIPK1)/RIPK3 and mixed lineage kinase domain-like kinase (MLKL). Treatment with RIPK1 inhibitors (necrostatin-1 or 7-Cl-O-Nec-1) significantly reversed acetylshikonin-induced MLKL phosphorylation and NSCLC cell death. These results indicate that acetylshikonin activated the RIPK1/RIPK3/MLKL cascade, leading to necroptosis in NSCLC cells. Our findings indicate that acetylshikonin reduces lung cancer cells by promoting G2/M phase arrest and necroptosis.

Mechanism of multidrug resistance to chemotherapy mediated by P‑glycoprotein (Review)

Multidrug resistance (MDR) seriously limits the clinical application of chemotherapy. A mechanism underlying MDR is the overexpression of efflux transporters associated with chemotherapeutic drugs. P‑glycoprotein (P‑gp) is an ATP‑binding cassette (ABC) transporter, which promotes MDR by pumping out chemotherapeutic drugs and reducing their intracellular concentration. To date, overexpression of P‑gp has been detected in various types of chemoresistant cancer and inhibiting P‑gp‑related MDR has been suggested. The present review summarizes the mechanisms underlying MDR mediated by P‑gp in different tumors and evaluated the related signaling pathways, with the aim of improving understanding of the current status of P‑gp‑mediated chemotherapeutic resistance. This review focuses on the main mechanisms of inhibiting P‑gp‑mediated MDR, with the aim of providing a reference for the study of reversing P‑gp‑mediated MDR. The first mechanism involves decreasing the efflux activity of P‑gp by altering its conformation or hindering P‑gp‑chemotherapeutic drug binding. The second inhibitory mechanism involves inhibiting P‑gp expression to reduce efflux. The third inhibitory mechanism involves knocking out the ABCB1 gene. Potential strategies that can inhibit P‑gp include certain natural products, synthetic compounds and biological techniques. It is important to screen lead compounds or candidate techniques for P‑gp inhibition, and to identify inhibitors by targeting the relevant signaling pathways to overcome P‑gp‑mediated MDR.

Anticancer and chemosensitizing activities of stilbenoids from three orchid species

Recently, we have isolated and identified several bioactive flavonoids and stilbenoids with potential anticancer activity from Thai orchids. In this study, we further investigated the cytotoxic and chemosensitizing activities of these phytochemicals (namely, pinocembrin, cardamonin, isalpinin, galangin, pinosylvin monomethyl ether, 2,3'-dihydroxy-5'-methoxystilbene, (E)-2,5'-dihydroxy-2'-(4-hydroxybenzyl)-3'-methoxystilbene, 2,3-dihydroxy-3',5'-dimethoxystilbene, 2,3'-dihydroxy-5,5'-dimethoxystilbene, 3,4'-dihydroxy-5-methoxystilbene and batatasin III) against breast cancer MCF7 cells and its two multidrug resistant (MDR) sublines (MCF7/DOX and MCF7/MX). Cytotoxicity was determined with MTT assay for the estimation of the half maximal cytotoxic concentrations (IC₅₀). Effects of the test compounds on activities of efflux transporters (BCRP, P-gp, MRP1, and MRP2) were evaluated with substrate accumulation assays using fluorometry and flow cytometry analysis. Out of these 11 test compounds, the stilbene pinosylvin monomethyl ether displayed its cytotoxicity specifically toward MCF7 cells (IC₅₀ = 6.2 ± 1.2 μM, 72-h incubation) with 4.96 folds higher than normal fibroblast. Its potency decreased in MCF7/DOX and MCF7/MX cells by 3.94 and 7.38 folds, respectively. Our transporter assay indicated that this stilbene significantly reduced the activities of P-gp, MRP1, and MRP2, but not BCRP. After 48-h co-incubation, this stilbene (at 2 μM) synergistically increased doxorubicin- and mitoxantrone-mediated cytotoxicity in MCF7, MCF7/DOX, and MCF7/MX cells potentially by increasing the intracellular level of cytotoxic drug. Pinosylvin monomethyl ether could sensitize breast cancer cells to chemotherapy and overcome MDR, in part, via the inhibition of drug efflux transporters.

Natural products as chemo-radiation therapy sensitizers in cancers

Cancer is a devastating disease and is the second leading cause of death worldwide. Surgery, chemotherapy (CT), and/or radiation therapy (RT) are the treatment of choice for most advanced tumors. Unfortunately, treatment failure due to intrinsic and acquired resistance to the current CT and RT is a significant challenge associated with poor patient prognosis. There is an urgent need to develop and identify agents that can sensitize tumor cells to chemo-radiation therapy (CRT) with minimal cytotoxicity to the healthy tissues. While many recent studies have identified the underlying molecular mechanisms and therapeutic targets for CRT failure, using small molecule inhibitors to chemo/radio sensitize tumors is associated with high toxicity and increased morbidity. Natural products have long been used as chemopreventive agents in many cancers. Combining many of these compounds with the standard chemotherapeutic agents or with RT has shown synergistic effects on cancer cell death and overall improvement in patient survival. Based on the available data, there is strong evidence that natural products have a robust therapeutic potential along with CRT and their well-known chemopreventive effects in many solid tumors. This review article reports updated literature on different natural products used as CT or RT sensitizers in many solid tumors. This is the first review discussing CT and RT sensitizers together in cancer.

Advancements in redox-sensitive micelles as nanotheranostics: A new horizon in cancer management

World Health Organisation (WHO) delineated cancer as one of the foremost reasons for mortality with 10 million deaths in the year 2020. Early diagnosis and effective drug delivery are of utmost importance in cancer management. The entrapment of both bio-imaging dyes and drugs will open novel avenues in the area of tumor theranostics. Elevated levels of reactive oxygen species (ROS) and glutathione (GSH) are the characteristic features of the tumor microenvironment (TME). Researchers have taken advantage of these specific TME features in recent years to develop micelle-based theranostic nanosystems. This review focuses on the advantages of redox-sensitive micelles (RSMs) and supramolecular self-assemblies for tumor theranostics. Key chemical linkers employed for the tumor-specific release of the cargo have been discussed. In vitro characterisation techniques used for the characterization of RSMs have been deliberated. Potential bottlenecks that may present themselves in the bench-to-bedside translation of this technology and the regulatory considerations have been deliberated.

Inventory of ATP-binding cassette proteins in Lithospermum erythrorhizon as a model plant producing divergent secondary metabolites

ATP-binding cassette (ABC) proteins are the largest membrane transporter family in plants. In addition to transporting organic substances, these proteins function as ion channels and molecular switches. The development of multiple genes encoding ABC proteins has been associated with their various biological roles. Plants utilize many secondary metabolites to adapt to environmental stresses and to communicate with other organisms, with many ABC proteins thought to be involved in metabolite transport. Lithospermum erythrorhizon is regarded as a model plant for studying secondary metabolism, as cells in culture yielded high concentrations of meroterpenes and phenylpropanoids. Analysis of the genome and transcriptomes of L. erythrorhizon showed expression of genes encoding 118 ABC proteins, similar to other plant species. The number of expressed proteins in the half-size ABCA and full-size ABCB subfamilies was ca. 50% lower in L. erythrorhizon than in Arabidopsis, whereas there was no significant difference in the numbers of other expressed ABC proteins. Because many ABCG proteins are involved in the export of organic substances, members of this subfamily may play important roles in the transport of secondary metabolites that are secreted into apoplasts.

Single-Cell Image-Based Analysis Reveals Chromatin Changes during the Acquisition of Tamoxifen Drug Resistance

Cancer drug resistance is the leading cause of cancer related deaths. The development of drug resistance can be partially contributed to tumor heterogeneity and epigenetic plasticity. However, the detailed molecular mechanism underlying epigenetic modulated drug resistance remains elusive. In this work, we systematically analyzed epigenetic changes in tamoxifen (Tam) responsive and resistant breast cancer cell line MCF7, and adopted a data-driven approach to identify key epigenetic features distinguishing between these two cell types. Significantly, we revealed that DNA methylation and H3K9me3 marks that constitute the heterochromatin are distinctively different between Tam-resistant and -responsive cells. We then performed time-lapse imaging of 5mC and H3K9me3 features using engineered probes. After Tam treatment, we observed a slow transition of MCF7 cells from a drug-responsive to -resistant population based on DNA methylation features. A similar trend was not observed using H3K9me3 probes. Collectively, our results suggest that DNA methylation changes partake in the establishment of Tam-resistant breast cancer cell lines. Instead of global changes in the DNA methylation level, the distribution of DNA methylation features inside the nucleus can be one of the drivers that facilitates the establishment of a drug resistant phenotype in MCF7.

Predictive Value of MRP-1 in Localized High-Risk Soft Tissue Sarcomas: A Translational Research Associated to ISG-STS 1001 Randomized Phase III Trial

MRP-1 is implicated in multidrug resistance and was described as prognostic in high-risk patients with soft-tissue sarcoma (STS) in a previous study. The current research aimed to validate MRP-1 prognostic/predictive value in localized sarcomas treated with anthracyclines plus ifosfamide within the ISG-1001 phase III study. In addition, the inhibitory activity on MRP-1 was investigated in preclinical studies to identify new combinations able to increase the efficacy of standard chemotherapy in STS. MRP-1 expression was assessed by IHC in tissue microarrays from patients with STS and tested for correlation with disease-free survival (DFS) and overall survival (OS). In vitro studies tested the efficacy of MRP-1 inhibitors (nilotinib, ripretinib, selumetinib, and avapritinib) in sarcoma cell lines. The effect of combinations of the most active MRP-1 inhibitors and chemotherapy was measured on the basis of apoptosis. MRP-1 was evaluable in 231 of 264 cases who entered the study. MRP-1 expression (strong intensity) was independently associated with worse DFS [HR, 1.78; 95% confidence interval (CI), 1.11-2.83; P = 0.016], in the multivariate analysis, with a trend for a worse OS (HR, 1.78; 95% CI, 0.97-3.25; P = 0.062). In vitro studies showed that the addition of MRP-1 inhibitors (nilotinib or avapritinib) to doxorubicin plus palifosfamide, significantly increased cell death in SK-UT-1 and CP0024 cell lines. MRP-1 is an adverse predictive factor in localized high-risk patients with STS treated with neoadjuvant anthracyclines plus ifosfamide followed by surgery. In vitro findings support the clinical assessment of the combination of chemotherapy and MRP-1 inhibitors as a promising strategy to overcome the drug ceiling effect for chemotherapy.

Targeting Drug Chemo-Resistance in Cancer Using Natural Products

Cancer is one of the leading causes of death globally. The development of drug resistance is the main contributor to cancer-related mortality. Cancer cells exploit multiple mechanisms to reduce the therapeutic effects of anticancer drugs, thereby causing chemotherapy failure. Natural products are accessible, inexpensive, and less toxic sources of chemotherapeutic agents. Additionally, they have multiple mechanisms of action to inhibit various targets involved in the development of drug resistance. In this review, we have summarized the basic research and clinical applications of natural products as possible inhibitors for drug resistance in cancer. The molecular targets and the mechanisms of action of each natural product are also explained. Diverse drug resistance biomarkers were sensitive to natural products. P-glycoprotein and breast cancer resistance protein can be targeted by a large number of natural products. On the other hand, protein kinase C and topoisomerases were less sensitive to most of the studied natural products. The studies discussed in this review will provide a solid ground for scientists to explore the possible use of natural products in combination anticancer therapies to overcome drug resistance by targeting multiple drug resistance mechanisms.

Normalizing Tumor Vasculature to Reduce Hypoxia, Enhance Perfusion, and Optimize Therapy Uptake

Simple Summary

In order for solid tumors to grow, they need to develop new blood vessels in order to support their increasing metabolic requirements. To facilitate the novel vessel formation, the tumor initiates an aggressive pro-angiogenic program. As a result of the aggressive angiogenesis, blood vessels form very rapidly and are often malformed and dysfunctional. There is a reduction in perfusion to the tumor, and often the tumors exhibit significant areas of tumor hypoxia. This review paper discusses the pro-tumorigenic environment induced by tumor hypoxia and how this can be targeted through normalization of the tumor vasculature. Here, we review tumor angiogenesis, the development of a hypoxic phenotype, and how this contributes to sustained tumorigenesis and resistance to therapy. We further discuss the potential of vascular normalization to reduce tumor hypoxia and facilitate uptake and efficacy of a variety of therapies.

Abstract

A basic requirement of tumorigenesis is the development of a vascular network to support the metabolic requirements of tumor growth and metastasis. Tumor vascular formation is regulated by a balance between promoters and inhibitors of angiogenesis. Typically, the pro-angiogenic environment created by the tumor is extremely aggressive, resulting in the rapid vessel formation with abnormal, dysfunctional morphology. The altered morphology and function of tumor blood and lymphatic vessels has numerous implications including poor perfusion, tissue hypoxia, and reduced therapy uptake. Targeting tumor angiogenesis as a therapeutic approach has been pursued in a host of different cancers. Although some preclinical success was seen, there has been a general lack of clinical success with traditional anti-angiogenic therapeutics as single agents. Typically, following anti-angiogenic therapy, there is remodeling of the tumor microenvironment and widespread tumor hypoxia, which is associated with development of therapy resistance. A more comprehensive understanding of the biology of tumor angiogenesis and insights into new clinical approaches, including combinations with immunotherapy, are needed to advance vascular targeting as a therapeutic area.

Elucidating the mechanisms of Temozolomide resistance in gliomas and the strategies to overcome the resistance

Temozolomide (TMZ) is a first-choice alkylating agent inducted as a gold standard therapy for glioblastoma multiforme (GBM) and astrocytoma. A majority of patients do not respond to TMZ during the course of their treatment. Activation of DNA repair pathways is the principal mechanism for this phenomenon that detaches TMZ-induced O-6-methylguanine adducts and restores genomic integrity. Current understanding in the domain of oncology adds several other novel mechanisms of resistance such as the involvement of miRNAs, drug efflux transporters, gap junction's activity, the advent of glioma stem cells as well as upregulation of cell survival autophagy. This review describes a multifaceted account of different mechanisms responsible for the intrinsic and acquired TMZ-resistance. Here, we summarize different strategies that intensify the TMZ effect such as MGMT inhibition, development of novel imidazotetrazine analog, and combination therapy; with an aim to incorporate a successful treatment and increased overall survival in GBM patients.

Muscles proteome analysis; irisin administration mimics some molecular effects of exercise in quadriceps muscle

Because of health-promoting effects, the adaptation of skeletal muscles to exercise is considered a therapeutic strategy for metabolic complications and musculoskeletal disabilities. Myokines display many beneficial effects of different exercise modalities. Among them, irisin is known as a systemic effector that positively influences several organs. There are a few studies about the effects of irisin on skeletal muscles, and irisin prosperities need to be well-defined for being an exercise mimetic. To aim this purpose, we assessed the proteome profile of mouse skeletal muscle after eight weeks of irisin injection comparing to resistance and endurance exercise treated groups. In the current study, two-dimensional gel electrophoresis was used to evaluate the protein content of the quadriceps muscle. The results were analyzed with Image Master 2D Platinum V6 software. Differentially expressed proteins were characterized by mass spectrometry (MALDI TOF/TOF) and interpreted using protein data banks and co-expression network. Irisin increases cellular ATP content by driving its overproduction through glycolysis and oxidative phosphorylation similar to two exercise protocols and as a specific property, decreases ATP consumption through creatine kinase downregulation. It also improves the microstructural properties of quadriceps muscle by increasing fiber proteins and might induce cellular proliferation and differentiation. Network analysis of differentially expressed proteins also revealed the co-expression of Irisin precursor with structural and metabolic-related proteins. The protein alterations after irisin administration display the potential of this myokine to mimic some molecular effects of exercise, suggesting it a promising candidate to improve muscle metabolism and structure.

Assessment of Skin Photoallergy Risk in Cosmetics Containing Herbal Extract Ingredients

BACKGROUND/OBJECTIVE

In recent years, herbal extracts are becoming increasingly popular ingredients added in cosmetics; however, the assessment of their potential adverse effects on the skin remains unclear. As Coptis, Phellodendron amurense, curcumin, and shikonin are herbs currently used in cosmetic ingredients, the aim of this study was to assess their skin photoallergy (PA) potential and the concentrations at which they could safely be used.

METHODS

In the patch test, Coptis, P. amurense, curcumin, and shikonin with 5, 10, 25, and 50% concentration were applied on 33 healthy Chinese subjects using the T.R.U.E. TEST® patch test system for 48 h. Photopatch testing was performed on 206 Chinese subjects with predisposed photosensitivity history using the Scandinavian photopatch series, and subjects were irradiated by 50% UVA minimum erythema dose. Photopatch testing of herbal extracts was then performed on subjects diagnosed with PA.

RESULTS

Thirty-three subjects (14 with type III skin and 19 with type IV skin) completed contact patch testing of herbal extracts. Coptis induced a contact allergy (CA) reaction on 2 subjects at 25% concentration and on 2 subjects at 10% concentration. P. amurense induced a CA reaction on 1 subject at 10% concentration and on 1 subject at 5% concentration. Shikonin induced a stimulating reaction on 1 subject at 10% concentration. Curcumin induced a stimulating reaction on 1 subject at 10% concentration. Of the 206 Chinese subjects predisposed for photosensitivity, 10.19% had PA, 16.5% showed CA, and 1.45% had both PA + CA. PA-induced substances were promethazine hydrochloride (15%, n = 31), chlorpromazine hydrochloride (10.84%, n = 19), perfume mix (5.82%, n = 12), atranorin (3.39%, n = 7), 6-methyl coumarine (3.39%, n = 7), balsam Peru (1.94%, n = 4), fentichlor (1.94%, n = 4), 3,3',4',5-tetrachloro salicylanilide (0.97%, n = 2), hexachlorophene (0.97%, n = 2), chlorhexidine digluconate (0.97%, n = 2), and 4-aminobenzoic acid 2-hydroxy-4-methoxybenzophenone (0.97%, n = 2). Coptis at 25, 10, and 5% concentration and P. amurense, shikonin, and curcumin each at 10 and 5% concentration induced negative photopatch test results in all 10 photosensitive subjects.

CONCLUSION

We have shown that Coptis, shikonin, or curcumin at 5% concentration in cosmetics could be applied safely without inducing contact allergic and photosensitive reactions on the skin. These findings advance the understanding of herbal extract use in cosmetic ingredients as related to the fields of dermatopharmacology and dermatotoxicology.

Pharmacology, toxicity and pharmacokinetics of acetylshikonin: a review

CONTEXT

Acetylshikonin, a naphthoquinone derivative, is mainly extracted from some species of the family Boraginaceae, such as Lithospermum erythrorhizon Sieb. et Zucc., Arnebia euchroma (Royle) Johnst., and Arnebia guttata Bunge. As a bioactive compound, acetylshikonin has attracted much attention because of its broad pharmacological properties.

OBJECTIVE

This review provides a comprehensive summary of the pharmacology, toxicity, and pharmacokinetics of acetylshikonin focussing on its mechanisms on the basis of currently available literature.

METHODS

The information of acetylshikonin from 1977 to 2020 was collected using major databases including Elsevier, Scholar, PubMed, Springer, Web of Science, and CNKI. Acetylshikonin, pharmacology, toxicity, pharmacokinetics, and naphthoquinone derivative were used as key words.

RESULTS

According to emerging evidence, acetylshikonin exerts a wide spectrum of pharmacological effects such as anticancer, anti-inflammatory, lipid-regulatory, antidiabetic, antibacterial, antifungal, antioxidative, neuroprotective, and antiviral properties. However, only a few studies have reported the adverse effects of acetylshikonin, with respect to reproductive toxicity and genotoxicity. Pharmacokinetic studies demonstrate that acetylshikonin is associated with a wide distribution and poor absorption.

CONCLUSIONS

Although experimental data supports the beneficial effects of this compound, acetylshikonin cannot be considered as a therapy drug without further investigations, especially, on the toxicity and pharmacokinetics.

A High-Resolution Mass Spectrometry-Based Quantitative Metabolomic Workflow Highlights Defects in 5-Fluorouracil Metabolism in Cancer Cells with Acquired Chemoresistance

Currently, 5-fluorouracil (5-FU)-based combination chemotherapy is the mainstay in the treatment of metastatic colorectal cancer (CRC), which benefits approximately 50% of the patients. However, these tumors inevitably acquire chemoresistance resulting in treatment failure. The molecular mechanisms driving acquired chemotherapeutic drug resistance in CRC is fundamental for the development of novel strategies for circumventing resistance. However, the specific phenomenon that drives the cancer cells to acquire resistance is poorly understood. Understanding the molecular mechanisms that regulate chemoresistance will uncover new avenues for the treatment of CRC. Among the various mechanisms of acquired chemoresistance, defects in the drug metabolism pathways could play a major role. In the case of 5-FU, it gets converted into various active metabolites, which, directly or indirectly, interferes with the replication and transcription of dividing cells causing DNA and RNA damage. In this project, we developed a high-resolution mass spectrometry-based method to effectively extract and quantify levels of the 5-FU metabolites in cell lysates and media of parental and 5-FU resistant LIM1215 CRC cells. The analysis highlighted that the levels of 5-FU metabolites are significantly reduced in 5-FU resistant cells. Specifically, the level of the nucleotide fluorodeoxyuridine monophosphate (FdUMP) is reduced with treatment of 5-FU clarifying the compromised 5-FU metabolism in resistant cells. Corroborating the metabolomic analysis, treatment of the resistant cells with FdUMP, an active metabolite of 5-FU, resulted in effective killing of the resistant cells. Overall, in this study, an effective protocol was developed for comparative quantitation of polar metabolites and nucleotide analogues from the adherent cells efficiently. Furthermore, the utility of FdUMP as an alternative for CRC therapy is highlighted.

Reversal Effect of ALK Inhibitor NVP-TAE684 on ABCG2-Overexpressing Cancer Cells

Failure of cancer chemotherapy is mostly due to multidrug resistance (MDR). Overcoming MDR mediated by overexpression of ATP binding cassette (ABC) transporters in cancer cells remains a big challenge. In this study, we explore whether NVP-TAE684, a novel ALK inhibitor which has the potential to inhibit the function of ABC transport, could reverse ABC transporter-mediated MDR. MTT assay was carried out to determine cell viability and reversal effect of NVP-TAE684 in parental and drug resistant cells. Drug accumulation and efflux assay was performed to examine the effect of NVP-TAE684 on the cellular accumulation and efflux of chemotherapeutic drugs. The ATPase activity of ABCG2 transporter in the presence or absence of NVP-TAE684 was conducted to determine the impact of NVP-TAE684 on ATP hydrolysis. Western blot analysis and immunofluorescence assay were used to investigate protein molecules related to MDR. In addition, the interaction between NVP-TAE684 and ABCG2 transporter was investigated via in silico analysis. MTT assay showed that NVP-TAE684 significantly decreased MDR caused byABCG2-, but not ABCC1-transporter. Drug accumulation and efflux tests indicated that the effect of NVP-TAE684 in decreasing MDR was due to the inhibition of efflux function of ABCG2 transporter. However, NVP-TAE684 did not alter the expression or change the subcellular localization of ABCG2 protein. Furthermore, ATPase activity analysis indicated that NVP-TAE684 could stimulate ABCG2 ATPase activity. Molecular in silico analysis showed that NVP-TAE684 interacts with the substrate binding sites of the ABCG2 transporter. Taken together, our study indicates that NVP-TAE684 could reduce the resistance of MDR cells to chemotherapeutic agents, which provides a promising strategy to overcome MDR.

Overexpression of ABCB1 Transporter Confers Resistance to mTOR Inhibitor WYE-354 in Cancer Cells

The overexpressing ABCB1 transporter is one of the key factors leading to multidrug resistance (MDR). Thus, many ABCB1 inhibitors have been found to be able to overcome ABCB1-mediated MDR. However, some inhibitors also work as a substrate of ABCB1, which indicates that in order to achieve an effective reversal dosage, a higher concentration is needed to overcome the pumped function of ABCB1, which may concurrently increase the toxicity. WYE-354 is an effective and specific mTOR (mammalian target of rapamycin) inhibitor, which recently has been reported to reverse ABCB1-mediated MDR. In the current study, 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay was carried out to determine the cell viability and reversal effect of WYE-354 in parental and drug-resistant cells. Drug accumulation was performed to examine the effect of WYE-354 on the cellular accumulation of chemotherapeutic drugs. The ATPase (adenosine triphosphatase) activity of the ABCB1 transporter in the presence or absence of WYE-354 was conducted in order to determine the impact of WYE-354 on ATP hydrolysis. Western blot analysis and immunofluorescence assay were used to investigate the protein molecules related to MDR. In addition, the interaction between the WYE-354 and ABCB1 transporter was investigated via in silico analysis. We demonstrated that WYE-354 is a substrate of ABCB1, that the overexpression of the ABCB1 transporter decreases the efficacy of WYE-354, and that the resistant WYE-354 can be reversed by an ABCB1 inhibitor at a pharmacological achievable concentration. Furthermore, WYE-354 increased the intracellular accumulation of paclitaxel in the ABCB1-mediated MDR cell line, without affecting the corresponding parental cell line, which indicated that WYE-354 could compete with other chemotherapeutic drugs for the ABCB1 transporter substrate binding site. In addition, WYE-354 received a high score in the docking analysis, indicating a strong interaction between WYE-354 and the ABCB1 transporter. The results of the ATPase analysis showed that WYE-354 could stimulate ABCB1 ATPase activity. Treatment with WYE-354 did not affect the protein expression or subcellular localization of the ABCB1. This study provides evidence that WYE-354 is a substrate of the ABCB1 transporter, implicating that WYE-354 should be avoided for use in ABCB1-mediated MDR cancer.

Competitive glucose metabolism as a target to boost bladder cancer immunotherapy

Bladder cancer - the tenth most frequent cancer worldwide - has a heterogeneous natural history and clinical behaviour. The predominant histological subtype, urothelial bladder carcinoma, is characterized by high recurrence rates, progression and both primary and acquired resistance to platinum-based therapy, which impose a considerable economic burden on health-care systems and have substantial effects on the quality of life and the overall outcomes of patients with bladder cancer. The incidence of urothelial tumours is increasing owing to population growth and ageing, so novel therapeutic options are vital. Based on work by The Cancer Genome Atlas project, which has identified targetable vulnerabilities in bladder cancer, immune checkpoint inhibitors (ICIs) have arisen as an effective alternative for managing advanced disease. However, although ICIs have shown durable responses in a subset of patients with bladder cancer, the overall response rate is only ~15-25%, which increases the demand for biomarkers of response and therapeutic strategies that can overcome resistance to ICIs. In ICI non-responders, cancer cells use effective mechanisms to evade immune cell antitumour activity; the overlapping Warburg effect machinery of cancer and immune cells is a putative determinant of the immunosuppressive phenotype in bladder cancer. This energetic interplay between tumour and immune cells leads to metabolic competition in the tumour ecosystem, limiting nutrient availability and leading to microenvironmental acidosis, which hinders immune cell function. Thus, molecular hallmarks of cancer cell metabolism are potential therapeutic targets, not only to eliminate malignant cells but also to boost the efficacy of immunotherapy. In this sense, integrating the targeting of tumour metabolism into immunotherapy design seems a rational approach to improve the therapeutic efficacy of ICIs.

Effect of β-cyclodextrin encapsulation on cytotoxic activity of acetylshikonin against HCT-116 and MDA-MB-231 cancer cell lines

Acetylshikonin (AcSh), as a red colored pigment found in roots of the plants from family Boraginaceae, showed excellent cytotoxic activity. Due to its hydrophobic nature, and thus poor bioavailability, the aim of this study was to prepare acetylshikonin/β-cyclodextrin (AcSh/β-CD) inclusion complex by using coprecipitation method, characterize obtained system by using UV/VIS, IR and ¹H NMR spectroscopy, and determine cytotoxic activity. Phase solubility test indicated formation of A_L-type binary system (substrate/ligand ratio was 1:1 M/M), with stability constant Ks of 306.01 M⁻¹. Formation of noncovalent bonds between inner layer of the hole of β-CD and AcSh was observed using spectroscopic methods. Notable changes in chemical shifts of two protons (−0.020 ppm) from naphthoquinone moiety (C₆-H and C₇-H), as well as protons from hydroxyl groups (−0.013 and −0.009, respectively) attached to C₅ and C₈ carbons from naphthoquinone part indicate that the molecule of AcSh enters the β-CD cavity from the aromatic side. Cytotoxic activity against HCT-116 and MDA-MB-231 cell lines was measured by MTT test and clonogenic assay. Mechanisms of action of free AcSh and inclusion complex were assessed by flow cytometry. In comparison to free AcSh, AcSh/β-CD showed stronger short-term effect on HCT-116 cells and superior long-term effect on both cell lines. Inclusion complex induced more pronounced cell cycle arrest and autophagy inhibition, and induced increase in accumulation of intracellular ROS more effectively than free AcSh. In conclusion, AcSh/β-CD binary system showed better performances regarding cytotoxic activity against tested tumor cell lines.

Inflammatory pathway interactions and cancer multidrug resistance regulation

Multidrug resistances against chemotherapeutics are among the major challenges related to cancer treatment. Recent studies have demonstrated that different conditions may tune the expression and activity of MDR transporters. For instance, inflammation occurs through a complex cytological process and chemical reactions in the most tumor microenvironment; it can play a critical role in cancer development and is capable of altering the expression and function of MDR transporters. Cytokines, interleukins, and prostaglandins are potent inflammatory mediators that can modulate the expression of MDRs at transcriptional and post-transcriptional levels in the most human cancer cells and tissues and potentially contribute to balance bioavailability of chemotherapeutic agents. Since cancer cases are usually accompanied by inflammatory responses, glucocorticoids and NSAIDs are the primary useful combination chemotherapies in a variety of cancer treatment protocols. In addition to the anti-inflammatory activities of these agents, they exert diverse modulatory effects on MDR-mediated drug resistance via specific mechanisms. Several factors, including cell and MDR-protein types, pharmacokinetics, and pharmacogenetics, mainly influence the regulatory mechanisms. Uncovering the networks between inflammation and multidrug resistance will be clinically helpful in the treatment of malignant cancers and decreasing the cancer mortality rates.

The CK2 inhibitor CX4945 reverses cisplatin resistance in the A549/DDP human lung adenocarcinoma cell line

Lung cancer negatively impacts global health, and the incidence of non-small cell lung cancer (NSCLC) is highest among all forms of lung cancer. Chemotherapy failure mainly occurs due to drug resistance; however, the associated molecular mechanism remains unclear. Casein kinase II (CK2), which plays important roles in the occurrence, development and metastasis of many tumours, regulates Wnt signaling by modulating β-catenin expression. In the present study the effects of the CK2 inhibitor, CX4945 on cisplatin [or cis-diamminedichloroplatinum (II); (DDP)]-resistant A549 cells (A549/DDP) were investigated to elucidate the underlying molecular mechanism. A549/DDP cells were divided into four groups (blank control, CX4945, cisplatin and CX4945+cisplatin). Cisplatin resistance was 5.16-fold greater in A549/DDP cells compared with that in A549 cells, with an optimal cisplatin concentration of 5 µg/ml. Moreover, levels of CK2, dishevelled-2 (DVL-2) phosphorylated (p) at Ser143 (p-DVL-2^Ser143), and major Wnt-signaling proteins were significantly higher in A549/DDP cells compared with that in A549 cells (P<0.05), with these levels further increased following cisplatin treatment (P<0.05), whereas these levels significantly decreased in A549 cells after cisplatin treatment (P<0.05). Additionally, multidrug-resistance-associated protein 1 and lung resistance protein expression was significantly higher in A549/DDP cells compared with that in A549 cells (P<0.05), with these levels increasing further in A549/DDP (P<0.05) but not A549 cells upon cisplatin treatment (P>0.05). In addition, reduced expression of resistance proteins in A549/DDP cells was accompanied by a decline in the 50% growth inhibition after CX4945 pre-treatment. Furthermore, levels of p-DVL-2^Ser143 and major Wnt-signaling proteins decreased significantly after treatment of A549/DDP cells with CX4945+cisplatin, whereas DVL-2 and p-DVL-2^Thr224 levels remained unchanged. Additionally, significant elevations in apoptosis rates in the CX4945+cisplatin group relative to the control and cisplatin-only groups, was observed (P<0.001). These results suggested that inhibiting Wnt/β-catenin signaling with CX4945, which attenuates levels of drug-resistance-associated proteins and induces apoptosis, might reverse cisplatin resistance in NSCLC.

Strategies to target bioactive molecules to subcellular compartments. Focus on natural compounds

Many potential pharmacological targets are present in multiple subcellular compartments and have different pathophysiological roles depending on location. In these cases, selective targeting of a drug to the relevant subcellular domain(s) may help to sharpen its impact by providing topological specificity, thus limiting side effects, and to concentrate the compound where needed, thus increasing its effectiveness. We review here the state of the art in precision subcellular delivery. The major approaches confer "homing" properties to the active principle via permanent or reversible (in pro-drug fashion) modifications, or through the use of special-design nanoparticles or liposomes to ferry a drug(s) cargo to its desired destination. An assortment of peptides, substituents with delocalized positive charges, custom-blended lipid mixtures, pH- or enzyme-sensitive groups provide the main tools of the trade. Mitochondria, lysosomes and the cell membrane may be mentioned as the fronts on which the most significant advances have been made. Most of the examples presented here have to do with targeting natural compounds - in particular polyphenols, known as pleiotropic agents - to one or the other subcellular compartment.

Shikonin derivatives for cancer prevention and therapy

Phytochemicals gained considerable interest during the past years as source to develop new treatment options for chemoprevention and cancer therapy. Motivated by the fact that a majority of established anticancer drugs are derived in one way or another from natural resources, we focused on shikonin, a naphthoquinone with high potentials to be further developed as preventive or therapeutic drug to fight cancer. Shikonin is the major chemical component of Lithospermum erythrorhizon (Purple Cromwell) roots. Traditionally, the root extract has been applied to cure dermatitis, burns, and wounds. Over the past three decades, the anti-inflammatory and anticancer effects of root extracts, isolated shikonin as well as semi-synthetic and synthetic derivatives and nanoformulations have been described. In vitro and in vivo experiments were conducted to understand the effect of shikonin at cellular and molecular levels. Preliminary clinical trials indicate the potential of shikonin for translation into clinical oncology. Shikonin exerts additive and synergistic interactions in combination with established chemotherapeutics, immunotherapeutic approaches, radiotherapy and other treatment modalities, which further underscores the potential of this phytochemical to be integrated into standard treatment regimens.

Intelligent TAT-coupled anti-HER2 immunoliposomes knock downed MDR1 to produce chemosensitize phenotype of multidrug resistant carcinoma

Gene therapy using biocompatible cationic liposomes is amongst promising approaches that decreases death from cancers. Here an invasive multidrug resistant cell model has been developed by lentiviral transfection. In parallel phospholipids have been covalently conjugated to TAT, MMP2, and Herceptin. The functional lipids have been mixed to generate intelligent liposome harboring small interfering RNA (siRNA) with high efficiency. The final liposomal complex was uniformly monodisperse and particle dimension and zeta-potential were respectively around 200 nm and -42.21 mV. Minimal cytotoxic effects have been reported for nanocarriers due to good biocompatibility of the selected phospholipids. Flourescence-activated cell sorter (FACS) analyses have been represented that surface trastuzumab and TAT specifically promote cellular uptake of liposomes in the malignant tumor cells. Assessment of MDR1 transcript and protein expression has been exhibited maximum significant downregulation around of 128-fold and 50-fold, respectively after 48 hr of liposome exposure. As it has been concluded, targeted liposomes may become a potential tool in gene delivery for improving chemotherapeutic efficiency in cancer treatment.

Unlike Butylcycloheptylprodigiosin, Isolated Undecylprodigiosin from Streptomyces parvulus Is Not a MDR1 and BCRP Substrate in Multidrug-Resistant Cancers

The search for new chemotherapeutics unaffected by efflux pumps would significantly increase life expectancy in patients with malignant cancers. In this study, butylcycloheptylprodigiosin and undecylprodigiosin were HPLC-purified and verified, using nuclear magnetic resonance spectroscopy. Cell cytotoxicity and transportation kinetics on multiple-drug resistance (MDR) cells were evaluated. Daunorubicin and butylcycloheptylprodigiosin were less toxic in the MDR1 overexpressing line, but undecylprodigiosin revealed potent toxicity toward MDR1 and BCRP expressing malignant cells. There was no noticeable change in MDR1 and BCRP transcripts during 3 days of treatment with prodiginines. While daunorubicin and mitoxantrone uptake from the cell environment significantly decreased with increasing multidrug resistance up to 46% and 62%, respectively, the accumulation of undecylprodigiosin and to a lesser extent butylcycloheptylprodigiosin in the resistance cells occurred cell- and dose-dependently via a passive diffusion process and were almost equally sensitive to the parent lines. The efflux of xenobiotics commenced immediately with different kinetics in various cells. A greater amount of daunorubicin and mitoxantrone were rapidly thrown out of their corresponding MDR cells in the absence of the specific inhibitor (3.01 and 1.81 dF/min, respectively) and represented functional efflux pumps. MDR pumps did not apparently influence undecylprodigiosin efflux patterns; but butylcycloheptylprodigiosin was partially removed from EPG85.257RDB cells at the rate of 2.66 and 1.41 dF/min in the absence and presence of verapamil, respectively.