Induction of human MDR1 gene expression by 2-acetylaminofluorene is mediated by effectors of the phosphoinositide 3-kinase pathway that activate NF-kappaB signaling

Intracellular TAS2Rs act as a gatekeeper for the excretion of harmful substances via ABCB1 in keratinocytes

Bitter taste receptors (TAS2Rs) are not only expressed in the oral cavity but also in skin. Extraoral TAS2Rs are thought to be involved in non-taste perception and tissue-specific functions. Keratinocytes that express TAS2Rs in the skin provide a first-line defense against external threats. However, the functional roles of these receptors in host defense remain unclear. Here, we demonstrated the sensory role of intracellularly located TAS2Rs against toxic substances in keratinocytes. Although many G protein-coupled receptors elicit signals from the surface, TAS2Rs were found to localize intracellularly, possibly to the ER, in human keratinocytes and HaCaT cells. TAS2R38, one of the TAS2R members, activated the Gα12/13/RhoA/ROCK/p38 MAP kinase/NF-κB pathway upon stimulation by phenylthiocarbamide (PTC), an agonist for this receptor, leading to the production of ABC transporters, such as ABCB1, in these cells. Notably, treatment with bitter compounds, such as PTC and saccharin, induced the upregulation of ABCB1 in HaCaT cells. Mechanistically, intracellular TAS2R38 and its downstream signaling Gα12/13/RhoA/ROCK/p38 MAP kinase/NF-κB pathway were identified to be responsible for the above effect. Pretreatment with PTC prevented the accumulation of rhodamine 123 because of its excretion via ABCB1. Furthermore, pretreatment with PTC or saccharin counteracted the effect of the toxic compound, diphenhydramine, and pretreated HaCaT cells were found to proliferate faster than untreated cells. This anti-toxic effect was suppressed by treatment with verapamil, an ABCB1 inhibitor, indicating that enhanced ABCB1 helps clear toxic substances. Altogether, harmless activators of TAS2Rs may be promising drugs that enhance the excretion of toxic substances from the human skin.

LAIR1 promotes hepatocellular carcinoma cell metastasis and induces M2-macrophage infiltration through activating AKT-IKKβ-p65 axis

LAIR1, a receptor found on immune cells, is capable of binding to collagen and is involved in immune-related diseases. However, the precise contribution of LAIR1 expressed on hepatocellular carcinoma (HCC) cells to tumor microenvironment is still unclear. In our study, bioinformatics analysis and immunofluorescence were employed to study the correlation between LAIR1 levels and clinical indicators. Transwell and scratch tests were used to evaluate how LAIR1 affected the migration and invasion of HCC cells. The chemotactic capacity and alternative activation of macrophages were investigated using RT-qPCR, transwell, and immunofluorescence. To investigate the molecular mechanisms, transcriptome sequencing analysis, Western blot, nucleus/cytoplasm fractionation, ELISA, and cytokine microarray were employed. We revealed a significant correlation between the presence of LAIR1 and an unfavorable outcome in HCC. We indicated that LAIR1 promoted migration and invasion of HCC cells through the AKT-IKKβ-p65 axis. Additionally, the alternative activation and infiltration of tumor-associated macrophages induced by LAIR1 were reliant on the upregulation of IL6 and CCL5 within this axis, respectively. In conclusion, blocking LAIR1 was found to be an effective approach in combating the cancerous advancement of HCC.

Impact of Combination Therapy with Chemical Drugs and Megavoltage X-ray Exposure on Breast Cancer Stem Cells' Viability and Proliferation of MCF-7 and MDA-MB-231 Cell Lines

BACKGROUND

Breast Cancer (BC) is a serious malignancy among women. However, chemotherapy is an important tool for cancer treatments, but the long-term use of chemotherapy drugs may lead to drug resistance and tumor recurrence. Since Breast Cancer Stem Cells (BCSCs) can be the main factor to induce BC treatment resistance and recurrence, investigation of BCSCs signaling pathways can be an effective modality to enhance cancer treatment efficiency.

OBJECTIVE

In this study, the effect of metformin, SB203580, and takinib alone or in combination with radiotherapy on MCF-7 and MDA-MB-231 breast cancer cell lines was evaluated.

METHODS

MCF-7 and MDA-MB-231 breast cancer cell lines were treated with metformin, SB203580, and takinib for 24 or 48 hours, followed by X-ray exposure. The MTT assay and flow cytometry analysis were performed to assess cell growth inhibition and cellular death, CXCr4 expression, and BCSCs, respectively.

RESULTS

The results showed the combination of takinib/SB203580 with radiotherapy to remarkably reduce the CXCR4 expression and BCSCs levels in the MCF-7 cell line. Also, the concurrent administration of takinib/metformin/radiotherapy significantly reduced BCSCs and CXCR4 metastatic markers in the MDA-MB- 231 cells. Since the MAPK signaling pathway has an important role in inducing drug resistance and cell proliferation, the use of SB203580 as an inhibitor of p38 MAPK can improve breast cancer treatment. Furthermore, metformin and ionizing radiation by suppression of the mTOR signaling pathway can control AMPK activation and cellular proliferation.

CONCLUSION

Anti-cancer and cytotoxic effects of metformin can be effective in this strategy. In conclusion, the combination of conventional chemotherapeutic drugs, including SB203580, metformin, and takinib with X-ray exposure can be a new approach to diminish the drug resistance of breast cancer.

Modulating multidrug resistance to drug-based antitumor therapies through NF-κB signaling pathway: mechanisms and perspectives

INTRODUCTION

Despite the advances made in cancer treatment in the past decades, therapeutic efficacy is still quite challenging, partially due to the emergence of multidrug resistance (MDR). It is crucial to decipher the underlying mechanisms of resistance in order to develop new therapeutic strategies for cancer patients. Previous studies have shown that activation of nuclear factor-κB (NF-κB) plays key roles in various cellular processes including proliferation, anti-apoptosis, metastasis, invasion, and chemoresistance.

AREAS COVERED

In this review, we conduct an integrated analysis of the evidence suggesting the vital roles of the NF-κB signaling pathway in MDR during chemotherapy, immunotherapy, endocrine, and targeted therapy. A literature search was performed on NF-κB and drug resistance in PubMed up to February 2023.

EXPERT OPINION

This review summarizes that the NF-κB signaling pathway exhibits a crucial role in enhancing drug resistance in chemotherapy, immunotherapy, endocrine, and targeted therapy. The application of combination therapy with existing antineoplastic drugs and a safe NF-κB inhibitor could become a promising strategy in cancer treatment. A better understanding of the pathway and mechanisms of drug resistance may help exploit safer and more effective NF-κB-targeting agents for clinical use in the future.

Fibrous stroma: Driver and passenger in cancer development

Cumulative evidence shows that fibrogenic stroma and stiff extracellular matrix (ECM) not only result from tumor growth but also play pivotal roles in cellular transformation and tumor initiation. This emerging concept may largely account for the increased cancer risk associated with environmental fibrogenic agents, such as asbestos and silica, and with chronic conditions that are fibrogenic, such as obesity and diabetes. It may also contribute to poor outcomes in patients treated with certain chemotherapeutics that can promote fibrosis, such as bleomycin and methotrexate. Although the mechanistic details of this phenomenon are still being unraveled, we provide an overview of the experimental evidence linking fibrogenic stroma and tumor initiation. In this Review, we will summarize the causes and consequences of fibrous stroma and how this stromal cue is transmitted to the nuclei of parenchymal cells through a physical continuum from the ECM to chromatin, as well as ECM-dependent biochemical signaling that contributes to cellular transformation.

Nek2 Kinase Signaling in Malaria, Bone, Immune and Kidney Disorders to Metastatic Cancers and Drug Resistance: Progress on Nek2 Inhibitor Development

Cell cycle kinases represent an important component of the cell machinery that controls signal transduction involved in cell proliferation, growth, and differentiation. Nek2 is a mitotic Ser/Thr kinase that localizes predominantly to centrosomes and kinetochores and orchestrates centrosome disjunction and faithful chromosomal segregation. Its activity is tightly regulated during the cell cycle with the help of other kinases and phosphatases and via proteasomal degradation. Increased levels of Nek2 kinase can promote centrosome amplification (CA), mitotic defects, chromosome instability (CIN), tumor growth, and cancer metastasis. While it remains a highly attractive target for the development of anti-cancer therapeutics, several new roles of the Nek2 enzyme have recently emerged: these include drug resistance, bone, ciliopathies, immune and kidney diseases, and parasitic diseases such as malaria. Therefore, Nek2 is at the interface of multiple cellular processes and can influence numerous cellular signaling networks. Herein, we provide a critical overview of Nek2 kinase biology and discuss the signaling roles it plays in both normal and diseased human physiology. While the majority of research efforts over the last two decades have focused on the roles of Nek2 kinase in tumor development and cancer metastasis, the signaling mechanisms involving the key players associated with several other notable human diseases are highlighted here. We summarize the efforts made so far to develop Nek2 inhibitory small molecules, illustrate their action modalities, and provide our opinion on the future of Nek2-targeted therapeutics. It is anticipated that the functional inhibition of Nek2 kinase will be a key strategy going forward in drug development, with applications across multiple human diseases.

Modulation of inflammation by phytochemicals to enhance efficacy and reduce toxicity of cancer chemotherapy

Treatment of cancer with chemotherapeutic drugs is associated with numerous adverse effects as well as the eventual development of resistance to chemotherapy. There is a great need for complementary therapies such as botanicals and nutritional supplements with little or no side effects that prevent resistance to chemotherapy and reduce its adverse effects. Inflammation plays a major role in the development of chemoresistance and the adverse effects of chemotherapy. Phytochemicals have well-established anti-inflammatory effects; thus, they could be used as complementary therapies along with chemotherapy to increase its efficacy and reduce its toxicity. Botanical compounds inhibit the NF-κB signaling pathway, which plays an important role in the generation of inflammation, chemotherapy resistance, and modulation of cell survival and apoptosis. Botanicals have previously been studied extensively for their cancer chemopreventive activities and are generally considered safe for human consumption. The present review focuses on the modulation of inflammation by phytochemicals and their role in increasing the efficacy and reducing the toxicity of cancer chemotherapy.

Design, synthesis, and biological evaluation of potent 1,2,3,4-tetrahydroisoquinoline derivatives as anticancer agents targeting NF-κB signaling pathway

The multifunctional transcription factor, nuclear factor-κB (NF-κB), is broadly involved in multiple human diseases, such as cancer and chronic inflammation, through abnormal modulations of the NF-κB signaling cascades. In patients with several types of cancer diseases, NF-κB is excessively activated, which could result in the stimulation of proliferation and/or suppression of apoptosis. Herein, we present a new series of 1,2,3,4-tetrahydroisoquinoline derivatives with good anticancer activities against various human cancer cell lines, which are rationally designed based on our novel NF-κB inhibitors. The SAR studies demonstrated that compound 5d with a methoxy group at the R₃ position exhibits the most anti-proliferative activity with GI₅₀ values, ranging 1.591 to 2.281 μM. Similar to KL-1156, the compound 5d (HSR1304) blocked NF-κB nuclear translocation step in LPS-stimulated MDA-MB-231 cells, probably leading to cytotoxic potency against tumor cells. Together with known potent NF-κB inhibitors containing diverse core heterocyclic moieties, the 1,2,3,4-tetrahydroisoquinoline derivatives can provide structural diversity, enhancing a potential for the development of a novel class of anticancer drugs.

Regulation of ABC Drug Efflux Transporters in Human T-Cells Exposed to an HIV Pseudotype

ATP-binding cassette (ABC) drug efflux transporters could contribute to low intracellular concentrations of antiretroviral drugs in HIV-1 cell reservoirs and sanctuary sites. Furthermore, the functional expression of these transporters could be induced in activated T-cells. Therefore, we investigated the expression of ABC drug efflux transporters in human T-cells exposed to an HIV pseudotype virus (pHIV_NL4-3), and further examined the potential involvement of the mammalian target of rapamycin (mTOR) signaling pathway in regulating their expression following exposure to pHIV_NL4-3. Additionally, we investigated the contribution of the drug efflux transporters to the inflammatory response following pHIV_NL4-3-induced T-cell activation. Human peripheral blood mononuclear cells (PBMCs) were exposed to HIV-1 envelope glycoprotein gp120_IIIB, pHIV_NL4-3 and/or mTOR inhibitors. The expression of ABC transporters, T-cell activation marker CD69, mTOR and pHIV_NL4-3 was assessed in CD4⁺ T-cells by Flow cytometry. mRNA and protein levels of proinflammatory cytokines (IL6, TNFα and INFγ) were examined in PBMCs by qPCR and ELISA analyses, respectively, following exposure to pHIV_NL4-3 with or without inhibitors of mTOR or ABC transporters. The expression of ABC transporters (P-glycoprotein, breast cancer resistance protein and multi-drug resistance associated protein-1) was significantly increased in CD4⁺ T-cells exposed to pHIV_NL4-3. Treatment with mTOR inhibitors attenuated pHIV_NL4-3-induced transporter expression, as well as mRNA and protein levels of IL6, TNFα and INFγ. Additionally, inhibition of P-gp or MRP1 activity resulted in lower concentrations of proinflammatory cytokines in supernatants of PBMC exposed to pHIV_NL4-3. Herein we present novel data demonstrating that upregulation of ABC drug efflux transporters could involve the mTOR signaling pathway in CD4⁺ T-cells exposed to an HIV pseudotype. These transporters could limit antiretroviral drug penetration in HIV target T-cells. Furthermore, ABC transporters could potentially contribute to HIV-associated proinflammatory cytokine secretion.

α-Mangostin Nanoparticles Cytotoxicity and Cell Death Modalities in Breast Cancer Cell Lines

α-Mangostin (AMG) is a potent anticancer xanthone that was discovered in mangosteen (Garcinia mangostana Linn.). AMG possesses the highest opportunity for chemopreventive and chemotherapeutic therapy. AMG inhibits every step in the process of carcinogenesis. AMG suppressed multiple breast cancer (BC) cell proliferation and apoptosis by decreasing the creation of cancerous compounds. Accumulating BC abnormalities and their associated molecular signaling pathways promotes novel treatment strategies. Chemotherapy is a commonly used treatment; due to the possibility of unpleasant side effects and multidrug resistance, there has been substantial progress in searching for alternative solutions, including the use of plant-derived natural chemicals. Due to the limitations of conventional cancer therapy, nanotechnology provides hope for effective and efficient cancer diagnosis and treatment. Nanotechnology enables the delivery of nanoparticles and increased solubility of drugs and drug targeting, resulting in increased cytotoxicity and cell death during BC treatment. This review summarizes the progress and development of AMG’s cytotoxicity and the mechanism of death BC cells. The combination of natural medicine and nanotechnology into a synergistic capital will provide various benefits. This information will aid in the development of AMG nanoparticle preparations and may open up new avenues for discovering an effective BC treatment.

Impact of Local Liver Irradiation Concurrent Versus Sequential with Lenvatinib on Pharmacokinetics and Biodistribution

Simple Summary

Lenvatinib is a systemic treatment for patients with advanced hepatocellular carcinoma (HCC). Stereotactic body radiation therapy (SBRT) is an advanced technique of hypofractionated external beam radiotherapy (EBRT) that can be applied in patients with HCC. The current study showed that the area under the concentration–time curve of lenvatinib concentration (AUC_lenvatinib) increased by 148.8% with radiotherapy (RT)_2Gy×3f’x (EBRT for the whole liver), and 68.9% with RT_9Gy×3f’× (SBRT targeting a 1.5 × 1.5 cm region in the center of the liver) in the sequential regimen compared to the concurrent regimen in rats. Additionally, the AUC_lenvatinib was decreased by 50% in the concurrent regimen of both RT techniques with lenvatinib compared to the control group. The biodistribution of lenvatinib in the organs at risk was markedly decreased in the concurrent regimens. The radiation–drug interactions were between lenvatinib and RT, and showed sequential preferably.

Abstract

Concurrent and sequential regimens involving radiotherapy (RT) and lenvatinib were designed with off-target or stereotactic body radiation therapy (SBRT) doses in a freely moving rat model to evaluate the effect of RT on the pharmacokinetics (PK) of lenvatinib. Liver RT concurrent with lenvatinib decreased the area under the concentration–time curve of lenvatinib concentration (AUC_lenvatinib) by 51.1% with three fractions of 2 Gy (RT_2Gy×3f’x, p = 0.03), and 48.9% with RT_9Gy×3f’x (p = 0.03). The AUC_lenvatinib increased by 148.8% (p = 0.008) with RT_2Gy×3f’x, and 68.9% (p = 0.009) with RT_9Gy×3f’x in the sequential regimen compared to the concurrent regimen. There were no differences in the AUC_lenvatinib between RT_2Gy×3f’x and RT_9Gy×3f’x in the concurrent or sequential regimen. Both the RT_2Gy×3f’x and RT_9Gy×3f’x concurrent regimens markedly decreased the biodistribution of lenvatinib in the heart, liver, lung, spleen, and kidneys, which ranged from 31% to 100% for RT_2Gy×3f’x, and 11% to 100% for RT_9Gy×3f’x, compared to the sham regimen. The PK and biodistribution of lenvatinib can be modulated by simultaneous off-target irradiation and SBRT doses. The timing of lenvatinib administration with respect to RT, impacted the PK and biodistribution of the drug. Additionally, off-target and SBRT doses had a similar ability to modulate the effect of systemic therapy.

Effect of Synchronous Versus Sequential Regimens on the Pharmacokinetics and Biodistribution of Regorafenib with Irradiation

This study was performed to evaluate the interaction between conventional or high-dose radiotherapy (RT) and the pharmacokinetics (PK) of regorafenib in concurrent or sequential regimens for the treatment of hepatocellular carcinoma. Concurrent and sequential in vitro and in vivo studies of irradiation and regorafenib were designed. The interactions of RT and regorafenib in vitro were examined in the human hepatoma Huh-7, HA22T and Hep G2 cell lines. The RT–PK phenomenon and biodistribution of regorafenib under RT were confirmed in a free-moving rat model. Regorafenib inhibited the viability of Huh-7 cells in a dose-dependent manner. Apoptosis in Huh-7 cells was enhanced by RT followed by regorafenib treatment. In the concurrent regimen, RT decreased the area under the concentration versus time curve (AUC)_regorafenib by 74% (p = 0.001) in the RT_{2 Gy × 3 fraction (f’x)} group and by 69% (p = 0.001) in the RT_{9 Gy × 3 f’x} group. The AUC_regorafenib was increased by 182.8% (p = 0.011) in the sequential RT_{2Gy × 1 f’x} group and by 213.2% (p = 0.016) in the sequential RT_{9Gy × 1 f’x} group. Both concurrent regimens, RT_{2Gy × 3 f’x} and RT_{9Gy × 3 f’x}, clearly decreased the biodistribution of regorafenib in the heart, liver, lung, spleen and kidneys, compared to the control (regorafenib _{× 3 d}) group. The concurrent regimens, both RT_{2Gy × 3 f’x} and RT_{9Gy × 3 f’x}, significantly decreased the biodistribution of regorafenib, compared with the control group. The PK of regorafenib can be modulated both by off-target irradiation and stereotactic body radiation therapy (SBRT).

Short-chain fatty acids exert opposite effects on the expression and function of p-glycoprotein and breast cancer resistance protein in rat intestine

P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are involved in intestinal barrier. Short-chain fatty acids (SCFAs) play important roles in maintaining intestinal barrier. In this study we explored how SCFAs affected the expression and function of intestinal P-gp and BCRP in rats. Rats received 150 mM acetate, propionate or butyrate in drinking water for 4 weeks. In SCFA-treated rats, the expression and function of intestinal P-gp were decreased, but those of intestinal BCRP were increased; intestinal p-p65 was also decreased, which was positively related to P-gp protein expression. Among the three SCFAs tested, butyrate exhibited the strongest induction or inhibitory effect, followed by propionate and acetate. Similar results were observed in mouse primary enterocytes and Caco-2 cells treated with acetate (5 mM), propionate (2 mM), or butyrate (1 mM). In Caco-2 cells, addition of butyrate, vorinostat, and valproate (two classic HDAC inhibitors), Bay117082 (selective inhibitor of NF-κB activation) or NF-κB p65 silencing significantly decreased the expression of P-gp and the level of phosphorylated p65 (p-p65). Furthermore, butyrate attenuated the expression of P-gp and p-p65 induced by TNF-α (NF-κB activator) and theophylline (HDAC activator). However, vorinostat, valproate, Bay117082, TNF-α or p65 silencing hardly affected BCRP protein expression. But GW9662 (selective PPARγ antagonist) or PPARγ silencing abolished BCRP induction by butyrate and troglitazone (PPARγ agonist). SCFAs-treated rats showed higher intestinal protein expression of PPARγ, which was positively related to BCRP protein expression. Butyrate increased plasma exposure of fexofenadine but decreased that of rosuvastatin following oral dose to rats. In conclusion, SCFAs exert opposite effects on the expression and function of intestinal P-gp and BCRP; butyrate downregulated P-gp expression and function possibly via inhibiting HDAC/NF-κB pathways; butyrate induced BCRP expression and function partly via PPARγ activation.

Differential sensitivity of renal carcinoma cells to doxorubicin and epigenetic therapeutics depends on the genetic background

Differential sensitivity to chemotherapeutics is a limitation in chemotherapy of kidney cancer patients. Role of genetic background in chemotherapy is not fully understood. Therefore, this study evaluated the influence of genetic/epigenetic background of renal cancer cells on the sensitivity to chemotherapeutics. Two renal cell carcinoma (RCC) cell lines, Caki-1 and 786-0, with different genetic makeup of p53 and VHL were treated with doxorubicin either alone or in combination with epigenetic therapeutics 5-aza-2-dc and TSA. Sensitivity of RCC cells to these drugs was evaluated by cell viability and cell cycle analysis and was further confirmed by analysis of selected genes expression. Cell viability data revealed that 786-0 cells were more sensitive than Caki-1 to doxorubicin. Combination of doxorubicin with 5-aza-2-dc or TSA was more effective to inhibit growth of Caki-1 cells but not the 786-0. Data of cell cycle analysis and expression of representative genes for tumor suppressor, cell cycle and survival, drug transporter and DNA repair further provided the molecular basis for differential sensitivity of Caki-1 and 786-0 cell lines to doxorubicin. Important findings of this study suggest that doxorubicin is more cytotoxic to primary renal cancer 786-0 cells with mutant VHL and p53 than the metastatic Caki-1 cells with wild-type VHL and p53, and this differential response was independent of p53 expression level. This study suggests that combination of doxorubicin with epigenetic therapeutics could potentially be beneficial in clinical treatment of renal cancer patients with wild-type VHL and p53 but not in patients with mutant VHL and p53.

Puerarin sensitized K562/ADR cells by inhibiting NF-κB pathway and inducing autophagy

Puerarin is an isoflavone isolated from Pueraria lobata (Willd.) Ohwi. In the present study, reversal effect and underlying mechanisms of puerarin on multidrug resistance (MDR) were investigated in K562/ADR cells. K562/ADR cells exhibited adriamycin (ADR) resistance and higher levels of MDR1 expression compared with K562 cells. Puerarin enhanced the chemosensitivity of K562/ADR cells and increased the ADR accumulation in K562/ADR cells. The expression levels of MDR1 were down-regulated by puerarin in K562/ADR cells. Luciferase reporter assay further demonstrated the inhibitory effect of puerarin on TNF-α-induced NF-κB activation. The phosphorylation of IκB-α was significantly suppressed by puerarin. In silico docking analyses suggested that puerarin well matched with the active sites of IκB-α. Moreover, a large number of autophagosomes were found in the cytoplasm of K562/ADR cells after puerarin treatment. The significant increase in LC3-II and beclin-1 was also observed, indicating autophagy induction by puerarin in K562/ADR cells. Puerarin induced cell cycle arrest and apoptosis in K562/ADR cells. Finally, puerarin inhibited phosphorylation of Akt and JNK. In conclusion, puerarin-sensitized K562/ADR cells by downregulating MDR1 expression via inhibition of NF-κB pathway and autophagy induction via Akt inhibition.

Possible Susceptibility Genes for Intervention against Chemotherapy-Induced Cardiotoxicity

Recent therapeutic advances have significantly improved the short- and long-term survival rates in patients with heart disease and cancer. Survival in cancer patients may, however, be accompanied by disadvantages, namely, increased rates of cardiovascular events. Chemotherapy-related cardiac dysfunction is an important side effect of anticancer therapy. While advances in cancer treatment have increased patient survival, treatments are associated with cardiovascular complications, including heart failure (HF), arrhythmias, cardiac ischemia, valve disease, pericarditis, and fibrosis of the pericardium and myocardium. The molecular mechanisms of cardiotoxicity caused by cancer treatment have not yet been elucidated, and they may be both varied and complex. By identifying the functional genetic variations responsible for this toxicity, we may be able to improve our understanding of the potential mechanisms and pathways of treatment, paving the way for the development of new therapies to target these toxicities. Data from studies on genetic defects and pharmacological interventions have suggested that many molecules, primarily those regulating oxidative stress, inflammation, autophagy, apoptosis, and metabolism, contribute to the pathogenesis of cardiotoxicity induced by cancer treatment. Here, we review the progress of genetic research in illuminating the molecular mechanisms of cancer treatment-mediated cardiotoxicity and provide insights for the research and development of new therapies to treat or even prevent cardiotoxicity in patients undergoing cancer treatment. The current evidence is not clear about the role of pharmacogenomic screening of susceptible genes. Further studies need to done in chemotherapy-induced cardiotoxicity.

Metformin Derivative HL156A Reverses Multidrug Resistance by Inhibiting HOXC6/ERK1/2 Signaling in Multidrug-Resistant Human Cancer Cells

Multidrug resistance is a significant clinical crisis in cancer treatment and has been linked to the cellular expression of multidrug efflux transporters. The aim of this study was to examine the effects and mechanisms of the metformin derivative HL156A on human multidrug resistance (MDR) cancer cells. Here, HL156A significantly suppressed cell growth and colony formation through G2/M phase cell cycle arrest in MDR cancer cells. HL156A also reduced the wound closure rate and cell migration and induced caspase-3-dependent apoptosis. We found that HL156A inhibited the expression of MDR1 by inhibiting the HOXC6-mediated ERK1/2 signaling pathway and increased the sensitivity to paclitaxel or doxorubicin in MDR cells. Furthermore, HL156A significantly inhibited angiogenesis in a chicken chorioallantoic membrane (CAM) assay. These results suggest the potential of the metformin derivative HL156A as a candidate therapeutic modality for the treatment of human multidrug-resistant cancers.

Citrus auraptene induces drug efflux transporter P-glycoprotein expression in human intestinal cells

P-glycoprotein (encoded by MDR1) is a membrane transport protein expressed in the intestine, liver, kidney, placenta, and blood-brain barrier. It excludes various clinically important drugs from cells, such as verapamil, digoxin, tacrolimus, and vinblastine. Therefore, human P-glycoprotein plays important roles in drug absorption, distribution, and excretion. We reported previously that auraptene, a natural compound occurring widely in citrus fruit (e.g., grapefruit), inhibited P-glycoprotein-mediated drug transport. In this study, we investigated the effects of auraptene and other phenylpropanoids on P-glycoprotein expression using human intestinal epithelial LS174T cells and a reporter plasmid expressing 10.2 kbp of the upstream regulatory region of MDR1. Auraptene (7-geranyloxycoumarin), a prenylated coumarin, and several phenylpropanoids, such as 3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans propenoic acid, derricidin [2'-hydroxy-4'-(prenyloxy)chalcone], and 3-(4'-geranyloxyphenyl)-propanoic acid, induced MDR1 promoter activity in LS174T cells. Overexpression of the nuclear receptor human pregnane X receptor gene (NR1I2) enhanced auraptene-induced MDR1 activation. Nuclear factor-kappaB inhibitors, Bay11-7082 and JSH-23, repressed MDR1 activation by auraptene. Western blot analyses showed the induction of P-glycoprotein expression in the auraptene-treated LS174T cells. The citrus phytochemical auraptene can induce the drug efflux transporter P-glycoprotein in human intestinal cells, and thus has the potential to cause food-drug interactions.

Effect of Mycobacterium tuberculosis Enhancement of Macrophage P-Glycoprotein Expression and Activity on Intracellular Survival During Antituberculosis Drug Treatment

BACKGROUND

Tuberculosis is caused by Mycobacterium tuberculosis. Recent emergence of multidrug-resistant (MDR) tuberculosis strains seriously threatens tuberculosis control and prevention. However, the role of macrophage multidrug resistance gene MDR1 on intracellular M. tuberculosis survival during antituberculosis drug treatment is not known.

METHODS

We used the human monocyte-derived macrophages to study the role of M. tuberculosis in regulation of MDR1 and drug resistance.

RESULTS

We discovered that M. tuberculosis infection increases the expression of macrophage MDR1 to extrude various chemical substances, including tuberculosis drugs, resulting in enhanced survival of intracellular M. tuberculosis. The pathway of regulation involves M. tuberculosis infection of macrophages and suppression of heat shock factor 1, a transcriptional regulator of MDR1 through the up-regulation of miR-431. Notably, nonpathogenic Mycobacterium smegmatis did not increase MDR1 expression, indicating active secretion of virulence factors in pathogenic M. tuberculosis contributing to this phenotype. Finally, inhibition of MDR1 improves antibiotic-mediated killing of M. tuberculosis.

CONCLUSION

We report a novel finding that M. tuberculosis up-regulates MDR1 during infection, which limits the exposure of M. tuberculosis to sublethal concentrations of antimicrobials. This condition promotes M. tuberculosis survival and potentially enhances the emergence of resistant variants.

FNDC5 promotes paclitaxel sensitivity of non-small cell lung cancers via inhibiting MDR1

Therapeutic benefits and clinical application of paclitaxel for treating non-small cell lung cancers (NSCLCs) are extremely hampered due to the chemoresistance. A recent study found that fibronectin type III domain-containing protein 5 (FNDC5) was downregulated in NSCLCs cells and negatively correlated with the clinicopathological characteristics in patients with NSCLCs. However, the role and potential molecular basis for FNDC5 in paclitaxel sensitivity of NSCLCs remain unclear. Paclitaxel-sensitive or resistant NSCLCs cell lines were exposed to small interfering RNA against FNDC5 (siFndc5) or recombinant irisin in the presence or absence of paclitaxel. NSCLCs cell lines have decreased FNDC5 expression compared with the normal human lung epithelial cells, which was further downregulated in paclitaxel-resistant cells. Irisin treatment suppressed, whereas Fndc5 silence promoted NSCLCs cells proliferation under basal conditions. Besides, we found that FNDC5 increased paclitaxel chemosensitivity in paclitaxel-sensitive or resistant NSCLCs cell lines via downregulating multidrug resistance protein 1 (MDR1). Further studies revealed that FNDC5 inhibited MDR1 expression via blocking nuclear factor-κB (NF-κB) activation. FNDC5 promotes paclitaxel sensitivity of NSCLCs cells via inhibiting NF-κB/MDR1 signaling, and FNDC5 might be a novel therapeutic target for the treatment of NSCLCs.

Association between ABCB1 (3435C>T) polymorphism and susceptibility of colorectal cancer: A meta-analysis

Studies on the relationship between ABCB1 3435C>T polymorphism (rs1045642) and colorectal cancer (CRC)susceptibility have yielded inconclusive results. To clarify this issue, we undertook a meta-analysis to investigate the relationship between rs1045642 and CRC risk.Three electronic scientific publication databases (Cochrane Library, Pubmed, Embase) were screened using specific search terms. Relevant literature was identified using literature traceability methods. Selected publications were evaluated according to the inclusion and exclusion criteria. Effect size information (odds ratio and the corresponding 95% confidence interval [CI]) was obtained following quality assessment and data extraction from the included publications, and a meta-analysis conducted. Statistical analysis was performed with the Stata sofz (Version 13.0) software.Overall, 17 case-control studies involving 7129 CRC patients and 7710 healthy control subjects satisfied the criteria for inclusion in the meta-analysis. There was no significant association between ABCB1 3435C>T polymorphism and CRC risk in any of the genetic models. In the CC versus CT model (I = 20.9%, Pheterogeneity = .276), CC versus CT + TT model (I = 45.6%, Pheterogeneity = .102) and CT versus CC + TT model (I = 17.8%, Pheterogeneity = .298) analyses, between-study heterogeneities were detected as significant in Asian populations. In the CT versus TT model (I = 24%, Pheterogeneity = .254) and CC + CT versus TT model (I = 0, Pheterogeneity = .55), between-study heterogeneities were found to be significant in groups of different populations.The meta-analysis described here suggests that the ABCB1 3435C>T polymorphism is not related to CRC susceptibility.

2,4,6-Tribromophenol Exposure Decreases P-Glycoprotein Transport at the Blood-Brain Barrier

2,4,6-Tribromophenol (TBP, CAS No. 118-79-6) is a brominated chemical used in the production of flame-retardant epoxy resins and as a wood preservative. In marine environments, TBP is incorporated into shellfish and consumed by predatory fish. Food processing and water treatment facilities produce TBP as a byproduct. 2,4,6-Tribromophenol has been detected in human blood and breast milk. Biologically, TBP interferes with estrogen and thyroid hormone signaling, which regulate important transporters of the blood-brain barrier (BBB). The BBB is a selectively permeable barrier characterized by brain microvessels which are composed of endothelial cells mortared by tight-junction proteins. ATP-binding cassette (ABC) efflux transporters on the luminal membrane facilitate the removal of unwanted endobiotics and xenobiotics from the brain. In this study, we examined the in vivo and ex vivo effects of TBP on two important transporters of the BBB: P-glycoprotein (P-gp, ABCB1) and Multidrug Resistance-associated Protein 2 (MRP2, ABCC2), using male and female rats and mice. 2,4,6-Tribromophenol exposure ex vivo resulted in a time- (1-3 h) and dose- (1-100 nM) dependent decrease in P-gp transport activity. MRP2 transport activity was unchanged under identical conditions. Immunofluorescence and western blotting measured decreases in P-gp expression after TBP treatment. ATPase assays indicate that TBP is not a substrate and does not directly interact with P-gp. In vivo dosing with TBP (0.4 µmol/kg) produced decreases in P-gp transport. Co-treatment with selective protein kinase C (PKC) inhibitors prevented the TBP-mediated decreases in P-gp transport activity.

Nek2B activates the wnt pathway and promotes triple-negative breast cancer chemothezrapy-resistance by stabilizing β-catenin

Background

The chemotherapy-resistance of triple-negative breast cancer (TNBC) remains a major challenge. The Nek2B kinase and β-catenin serve as crucial regulators of mitotic processes. The aim of this study was to test the correlation between Nek2B and TNBC chemotherapy sensitivity, and to determine the regulation of Nek2B on β-catenin and wnt/β-catenin signal pathway.

Methods

Gene Expression Omnibus(GEO) databases were used to gather gene exprsssion data of TNBC patients who undergoing chemotherapy. The co-expression of Nek2B and β-catenin in TNBC surgical sections and cells were analysed by immunohistochemistry, Q-RT-PCR, Western-blot and immunofluorescent staining. The impact of the expression of Nek2B and β-catenin in prognosis was also assessed using the Kaplan-Meier curves. CCK8 assay was used to detect the IC50 value of TNBC cell line. The endogenous binding capacity of Nek2B and β-catenin and phosphorylation of β-catenin by Nek2B were detected using co-immunoprecipitation (CO-IP). Chromatin immune-precipitation (ChIP) analysis and Luciferase Assays were used to evaluate the binding ability of the Nek2B, β-catenin and TCF4 complex with LEF-1 promoter. Nek2B-siRNA and Nek2B plasmid were injected into nude mice, and tumorigenesis was monitored.

Results

We found that overexpression of Nek2B and β-catenin in TNBC samples, was associated with patients poor prognosis. Patients with positive Nek2B expression were less sensitive to paclitaxel-containing neoadjuvant chemotherapy. Interestingly, in a panel of established TNBC cell line, Nek2B and β-catenin were highly expressed in cells exhibiting paclitaxel resistance. Our data also suggest that β-catenin binded to and was phosphorylated by Nek2B, and was in a complex with TCF4. Nek2B mainly regulates the expression of β-catenin in TNBC nucleus. Nek2B, β-catenin and TCF4 can be binded with the WRE functional area of LEF-1 promoter. Nek2B can activite wnt signaling pathway and wnt downstream target genes. The tumors treated by Nek2B siRNA associated with paclitaxel were the smallest in nude mouse, and Nek2B can regulate the expression of β-catenin and wnt downstream target genes in vivo.

Conclusion

Our study suggested that Nek2B can bind to β-catenin and the co-expression correlated with TNBC patients poor prognosis. It appears that Nek2B and β-catenin might synergize to promote chemotherapy resistance.

Optimal control nodes in disease-perturbed networks as targets for combination therapy

Most combination therapies are developed based on targets of existing drugs, which only represent a small portion of the human proteome. We introduce a network controllability-based method, OptiCon, for de novo identification of synergistic regulators as candidates for combination therapy. These regulators jointly exert maximal control over deregulated genes but minimal control over unperturbed genes in a disease. Using data from three cancer types, we show that 68% of predicted regulators are either known drug targets or have a critical role in cancer development. Predicted regulators are depleted for known proteins associated with side effects. Predicted synergy is supported by disease-specific and clinically relevant synthetic lethal interactions and experimental validation. A significant portion of genes regulated by synergistic regulators participate in dense interactions between co-regulated subnetworks and contribute to therapy resistance. OptiCon represents a general framework for systemic and de novo identification of synergistic regulators underlying a cellular state transition.

Synergistic interactions may arise between regulators in complex molecular networks. Here, the authors develop OptiCon, a computational method for de novo identification of synergistic key regulators and investigate their potential roles as candidate targets for combination therapy.

Acid ceramidase promotes drug resistance in acute myeloid leukemia through NF-κB-dependent P-glycoprotein upregulation

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. More than half of older AML patients fail to respond to cytotoxic chemotherapy, and most responders relapse with drug-resistant disease. Failure to achieve complete remission can be partly attributed to the drug resistance advantage of AML blasts that frequently express P-glycoprotein (P-gp), an ATP-binding cassette transporter. Our previous work showed that elevated acid ceramidase (AC) levels in AML contribute to blast survival. Here, we investigated P-gp expression levels in AML relative to AC. Using parental HL-60 cells and drug-resistant derivatives as our model, we found that P-gp expression and efflux activity were highly upregulated in resistant derivatives. AC overexpression in HL-60 conferred resistance to the AML chemotherapeutic drugs, cytarabine, mitoxantrone, and daunorubicin, and was linked to P-gp upregulation. Furthermore, targeting AC through pharmacologic or genetic approaches decreased P-gp levels and increased sensitivity to chemotherapeutic drugs. Mechanistically, AC overexpression increased NF-κB activation whereas NF-kB inhibitors reduced P-gp levels, indicating that the NF-kappaB pathway contributes to AC-mediated modulation of P-gp expression. Hence, our data support an important role for AC in drug resistance as well as survival and suggest that sphingolipid targeting approaches may also impact drug resistance in AML.

Obesity-Altered Adipose Stem Cells Promote ER⁺ Breast Cancer Metastasis through Estrogen Independent Pathways

Adipose stem cells (ASCs) play an essential role in tumor microenvironments. These cells are altered by obesity (obASCs) and previous studies have shown that obASCs secrete higher levels of leptin. Increased leptin, which upregulates estrogen receptor alpha (ERα) and aromatase, enhances estrogen bioavailability and signaling in estrogen receptor positive (ER⁺) breast cancer (BC) tumor growth and metastasis. In this study, we evaluate the effect of obASCs on ER⁺BC outside of the ERα signaling axis using breast cancer models with constitutively active ERα resulting from clinically relevant mutations (Y537S and D538G). We found that while obASCs promote tumor growth and proliferation, it occurs mostly through abrogated estrogen signaling when BC has constitutive ER activity. However, obASCs have a similar promotion of metastasis irrespective of ER status, demonstrating that obASC promotion of metastasis may not be completely estrogen dependent. We found that obASCs upregulate two genes in both ER wild type (WT) and ER mutant (MUT) BC: SERPINE1 and ABCB1. This study demonstrates that obASCs promote metastasis in ER WT and MUT xenografts and an ER MUT patient derived xenograft (PDX) model. However, obASCs promote tumor growth only in ER WT xenografts.

RPS15A promotes gastric cancer progression via activation of the Akt/IKK-β/NF-κB signalling pathway

This study aimed to investigate the clinical significance, potential biological function and underlying mechanism of RPS15A in gastric cancer (GC) progression. RPS15A expression was detected in 40 pairs of GC tissues and matched normal gastric mucosae (MNGM) using qRT‐PCR analysis. Immunohistochemistry assay was conducted using a tissue microarray including 186 primary GC samples to characterize the clinical significance of RPS15A. A series of in vitro and in vivo assays were performed to elucidate the biological function of RPS15A in GC development and underlying molecular mechanisms. The expression of RPS15A was significantly up‐regulated in GC samples compared to MNGM, and its expression was closely related to TNM stage, tumour size, differentiation, lymph node metastasis and poor patient survival. Ectopic expression of RPS15A markedly enhanced the proliferation and metastasis of GC cells both in vitro and in vivo. RPS15A overexpression also promoted the epithelial‐mesenchymal transition (EMT) phenotype formation of GC cells. Investigations of underlying mechanisms found that RPS15A activated the NF‐κB signalling pathway by inducing the nuclear translocation and phosphorylation of the p65 NF‐κB subunit, transactivation of NF‐κB reporter and up‐regulating target genes of this pathway. In addition, RPS15A overexpression activated, while RPS15A knockdown inhibited the Akt/IKK‐β signalling axis in GC cells. And both Akt inhibitor LY294002 and IKK inhibitor Bay117082 neutralized the p65 and p‐p65 nuclear translocation induced by RPS15A overexpression. Collectively, our findings suggest that RPS15A activates the NF‐κB pathway through Akt/IKK‐β signalling axis, and consequently promotes EMT and GC metastasis. This newly identified RPS15A/Akt/IKK‐β/NF‐κB signalling pathway may be a potential therapeutic target to prevent GC progression.

The regulation of drug-metabolizing enzymes and membrane transporters by inflammation: Evidences in inflammatory diseases and age-related disorders

Drug-metabolizing enzymes (DMEs) and membrane transporters play important roles in the absorption, distribution, metabolism, and excretion processes that determine the pharmacokinetics of drugs. Inflammation has been shown to regulate the expression and function of these drug-processing proteins. Given that inflammation is a common feature of many diseases, in this review, the general mechanisms for inflammation-mediated regulation of DMEs and transporters are described. Also, evidences regarding the aberrant expression of these drug-processing proteins in several inflammatory diseases and age-related disorders are provided.

Chloride channel-3 mediates multidrug resistance of cancer by upregulating P-glycoprotein expression

Chloride channel-3 (ClC-3), a member of the ClC family of voltage-gated Cl^- channels, is involved in the resistance of tumor cells to chemotherapeutic drugs. Here, we report a new mechanism for ClC-3 in mediating multidrug resistance (MDR). ClC-3 was highly expressed in the P-glycoprotein (P-gp)-dependent human lung adenocarcinoma cell line (A549)/paclitaxel (PTX) and the human breast carcinoma cell line (MCF-7)/doxorubicin (DOX) resistant cells. Changes in the ClC-3 expression resulted in the development of drug resistance in formerly drug-sensitive A549 or MCF-7 cells, and drug sensitivity in formerly drug-resistant A549/Taxol and MCF-7/DOX cells. Double transgenic MMTV-PyMT/CLCN3 mice with spontaneous mammary cancer and ClC-3 overexpression demonstrated drug resistance to PTX and DOX. ClC-3 expression upregulated the expression of MDR1 messenger RNA and P-gp by activating the nuclear factor-κB (NF-κB)-signaling pathway. These data suggest that ClC-3 expression in cancer cells induces MDR by upregulating NF-κB-signaling-dependent P-gp expression involving another new mechanism for ClC-3 in the development of drug resistance of cancers.

TIPE2 sensitizes osteosarcoma cells to cis-platin by down-regulating MDR1 via the TAK1- NF-κB and - AP-1 pathways

TIPE2 participates in multiple types of cancer development. However, its mechanism underlying chemoresistance in osteosarcoma has not been elucidated. Herein, we observed the expression of TIPE2 and MDR1 in cis-platin-resistant osteosarcoma tissues and cell lines. Compared to their matched sensitive cell lines and tissues, TIPE2 was downregulated while MDR1 expression was increased. Further investigation showed that overexpression of TIPE2 effectively inhibited MDR1 expression and greatly sensitized osteosarcoma cells to cis-platin, both in vivo and in vitro. Mechanistically, TIPE2 inhibited the transcription of the MDR1 promoter by interfering with the TAK1-NF-κB and -AP-1 pathways. Overall, our results elucidated for the first time that TIPE2 sensitizes osteosarcoma cells to cis-platin through downregulation of MDR1 and may be a novel target in osteosarcoma therapy.

An extracellular matrix (ECM) model at high malignant colorectal tumor increases chondroitin sulfate chains to promote epithelial-mesenchymal transition and chemoresistance acquisition

Chemoresistance is one of the major barriers for tumor chemotherapy. It is clinically known that chemoresistance increases during tumor progression. Additionally, the extracellular matrix (ECM) is also remodeled during tumor progression. However, it remains unclear how ECM remodeling contributes to chemoresistance acquisition. Recently, it has been reported that epithelial-mesenchymal transition (EMT) contributes to chemoresistance acquisition. Here, how ECM remodeling contributes to 5-fluorouracil (5-FU) resistance acquisition was investigated from the viewpoints of EMT using in vitro ECM models mimicking native ECM in colorectal tumor tissue at three different malignant levels. 5-FU partially induced EMT and increased ABCB1 in colorectal HT-29 cells via TGF-β signaling (an invasive tumor cell model). When HT-29 cells were cultured on an ECM model (high malignant matrices) mimicking native ECM in highly malignant tumor tissues, the cells facilitated TGF-β-induced EMT and increased ABCB1 upregulation compared with that of other ECM models mimicking the low malignant level and normal tissues. High malignant matrices contained more chondroitin sulfate (CS) chains than those of other ECM models. Finally, CS chain-reduced high malignant matrices could not facilitate ABCB1 upregulation and TGF-β-induced EMT. These results demonstrated that ECM remodeling during tumor progression increased CS chains to facilitate EMT and ABCB1 upregulation, contributing to chemoresistance acquisition.

Down-regulation of MDR1 by Ad-DKK3 via Akt/NFκB pathways augments the anti-tumor effect of temozolomide in glioblastoma cells and a murine xenograft model

BACKGROUND

Glioblastoma multiforme (GBM) is the most malignant of brain tumors. Acquired drug resistance is a major obstacle for successful treatment. Earlier studies reported that expression of the multiple drug resistance gene (MDR1) is regulated by YB-1 or NFκB via the JNK/c-Jun or Akt pathway. Over-expression of the Dickkopf (DKK) family member DKK3 by an adenovirus vector carrying DKK3 (Ad-DKK3) exerted anti-tumor effects and led to the activation of the JNK/c-Jun pathway. We investigated whether Ad-DKK3 augments the anti-tumor effect of temozolomide (TMZ) via the regulation of MDR1.

METHODS

GBM cells (U87MG and U251MG), primary TGB105 cells, and mice xenografted with U87MG cells were treated with Ad-DKK3 or TMZ alone or in combination.

RESULTS

Ad-DKK3 augmentation of the anti-tumor effects of TMZ was associated with reduced MDR1 expression in both in vivo and in vitro studies. The survival of Ad-DKK3-treated U87MG cells was inhibited and the expression of MDR1 was reduced. This was associated with the inhibition of Akt/NFκB but not of YB-1 via the JNK/c-Jun- or Akt pathway.

CONCLUSIONS

Our results suggest that Ad-DKK3 regulates the expression of MDR1 via Akt/NFκB pathways and that it augments the anti-tumor effects of TMZ in GBM cells.

Chemopreventive activity of celastrol in drug-resistant human colon carcinoma cell cultures

Celastrol (tripterine) a pentacyclic triterpenoid extracted from the roots of Tripterygium wilfordii Hook f., exhibits potent antioxidant and anti-inflammatory activity and also exerts important anti-cancer effects, as induction of apoptosis and lowering the level of drug resistance of several cancers. Increased level of cellular resistance to cytostatic drugs is typical for colorectal cancers, and largely determines the failure of chemotherapy for this tumor. The purpose of our research was to evaluate the chemopreventive effect of celastrol on cultures of colon cancer cells resistant to doxorubicin (LOVO/DX). With the use of flow cytometry we have shown that celastrol reduces the cell size of the SP (side population; subpopulation of cancer cells enriched with cancer stem cells), increases frequency of apoptosis and binds to Pgp protein in cell membranes inhibiting its transport function. The inhibition of the Pgp transport function has been shown to increase the accumulation of rhodamine-123 and standard cytostatic- doxorubicin in LOVO/DX cells. Our results prove that celastrol exhibits significant chemopreventive and chemosensitizing activities on drug resistant colon cancer cells. Celastrol appears to be a good candidate for adjuvant medicine that can improve the effectiveness of standard cytostatic therapy in humans.

Protective effects of curcumin against doxorubicin-induced toxicity and resistance: A review

Doxorubicin (DOX)-induced toxicity and resistance are major obstacles in chemotherapeutic approaches. Despite effective in the treatment of numerous malignancies, some clinicians have voiced concern that DOX has the potential to cause debilitating consequences in organ tissues, especially the heart. The mechanisms of toxicity and resistance are respectively related to induction of reactive oxygen species (ROS) and up-regulation of ATP-binding cassette (ABC) transporter. Curcumin (CUR) with several biological and pharmacological properties is expected to restore DOX-mediated impairments to tissues. This review is intended to address the current knowledge on DOX adverse effects and CUR protective actions in the heart, kidneys, liver, brain, and reproductive organs. Coadministration of CUR and DOX is capable of ameliorating DOX toxicity pertained to antioxidant, apoptosis, autophagy, and mitochondrial permeability.

Celecoxib enhances sensitivity to chemotherapy drugs of T-cell lymphoma

Celecoxib is a newly-identified nonsteroidal anti-inflammatory drug, which has been used to treat fever in clinical practice. Celecoxib has been demonstrated to suppress the viability of various human tumor cells. However, the effect of celecoxib on response of T-cell lymphoma to chemotherapy agents remains unclear. The aim of the present study was to investigate the effect of celecoxib on chemosensitivity of human T-cell lymphoma, and to address the underlying mechanism of action. The cytotoxicity of CDDP, epirubicin and VCR on Jurkat and Hut-78 cells treated with celecoxib was assessed by MTT assay, and the half-maximal inhibitory concentration (IC₅₀) value was calculated by Origin 75 software. The effect of celecoxib on apoptosis and intracellular concentration of Rhodamine-123 in Jurkat and Hut-78 cells was analyzed by flow cytometry. The expression of transcription factor p65 (p65), B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), multidrug resistance 1 (MDR1) and multidrug resistance-associated protein 1 (MRP1) at mRNA and protein levels were detected by reverse transcription quantitative polymerase chain reaction and western blotting, respectively. Proliferation suppression rates and apoptosis levels were significantly increased in Jurkat and Hut-78 cells combined with celecoxib compared with those without celecoxib, when treated with CDDP, epirubicin and VCR. The IC₅₀ values of the chemotherapy agents were lower in Jurkat and Hut-78 cells treated with celecoxib compared with those that were not. The apoptosis level, expression of Bax and the intracellular concentration of Rhodamine-123 were increased, whereas the expression of p65, Bcl-2, MDR1 and MRP1 were decreased, in celecoxib-treated Jurkat and Hut-78 cells compared with those without celecoxib treatment. These results indicated that celecoxib may enhance the sensitivity of T-cell lymphoma to chemotherapy drugs by inhibiting the expression of multidrug resistance (MDR)-associated proteins via downregulating the activity of the nuclear factor-κB signaling pathway, suggesting that celecoxib may improve the curative effect of chemotherapy drugs in T-cell lymphoma.

Visfatin mediates doxorubicin resistance in human colorectal cancer cells via up regulation of multidrug resistance 1 (MDR1)

Colorectal cancer (CRC) is one of the prevalent and deadly cancers worldwide. Chemotherapy resistance is one of the most challenging problems for CRC and other cancer treatments. Recent studies indicated that increasing levels of visfatin are correlated with worse clinical prognosis of CRC patients, while the effects and mechanisms of visfatin on progression of CRC remain unclear. Our present study established doxorubicin (Dox)-resistant CRC HCT-116 and SW480 cells (named HCT-116 Dox/R and SW480 Dox/R). The expression of visfatin, while not IL-6, IL-8, or TGF-β, in CRC Dox-resistant cells was significantly greater than that in their parental cells, while knockdown of visfatin by its specific siRNAs can elevate Dox sensitivity of CRC-resistant cells. In addition, si-visfatin can significantly down regulate the expression of multidrug resistance 1 (MDR1), while not multidrug resistance-associated protein 1 or lung resistance-related protein, in both HCT-116 Dox/R and SW480 Dox/R cells. Visfatin can regulate the transcription of MDR1 via modulating its promoter activities. Si-visfatin can also decrease the activation and nuclear localization of p65, one of the most important transcription factors for the expression of MDR1. Chromatin immunoprecipitation (ChIP) indicated that si-visfatin can suppress the binding between p65 and MDR1 promoter. Collectively, our present study revealed that visfatin mediates the Dox resistance of CRC cells via up regulation of MDR1. It indicated that targeted inhibition of visfatin might be helpful for overcoming Dox resistance of CRC therapy.

Silencing of Y-box binding protein-1 by RNA interference inhibits proliferation, invasion, and metastasis, and enhances sensitivity to cisplatin through NF-κB signaling pathway in human neuroblastoma SH-SY5Y cells

Y-box binding protein-1 (YB-1), a member of Y-box protein family binding DNA and RNA, has been proposed as a novel marker in multiple malignant tumors and found to be associated with tumor malignancy. Neuroblastoma is an embryonal tumor arising from neuroblast cells of the autonomic nervous system, which is the most common cancer diagnosed in infants. It has been reported that YB-1 is highly expressing in various human tumors including nasopharynx, thyroid, lung, breast, colon, ovary, and prostate cancers. This study aimed to investigate the functional role of YB-1 in neuroblastoma by silencing YB-1 using RNA interference (shRNA) in neuroblastoma SH-SY5Y cells. We found that silencing of YB-1 decreased the proliferation, migration, and invasion of SH-SY5Y cells. At molecular level, inhibition of YB-1 decreased the expression level of PCNA as well as MMP-2 in neuroblastoma SH-SY5Y cells. Also, we discovered that YB-1 silencing sensitized SH-SY5Y cells to cisplatin and promoted the apoptosis induced by cisplatin due to down-regulation of multidrug resistance (MDR) 1 protein via NF-κB signaling pathway. Therefore, we consider that targeting YB-1 is promising for neuroblastoma treatment and for overcoming its cisplatin resistance in the development of new neuroblastoma therapeutic strategies.

Combination of intensity modulated radiotherapy followed treatment with p38 MAPK activation inhibitor inhibits the proliferation of MCF-7 breast cancer cells

The present study was aimed to investigate the effect of intensity modulated radiotherapy (IMRT) followed by treatment with inhibitor for p38 MAPK, SB203580 on the rate of proliferation in drug resistant MCF-7 breast cancer cells. Interestingly, the results from immuno histochemistry and western blot assays revealed higher level of distribution of activated p38 MAPK in the drug resistant breast cancer tissues compared to the primary tissues. Treatment of the drug resistant MCF-7 cells with SB203580 led to a significant decrease in the phosphorylation of p38 MAPK. Exposure to IMRT caused a significant decrease in the rate of proliferation in drug resistant MCF-7breast cancer cells (P < 0.05). MCF-7 cells were subjected to IMRT for 45 min followed by treatment with SB203580 for 12 h. The results from MTT assay revealed inhibition in the rate of proliferation of MCF-7 cells more efficiently compared to the IMRT or SB203580 when used separately (P < 0.02). The effect of IMRT and SB203580 on inhibition of MCF-7 cell proliferation showed synergistic relation. Since MAPK signaling pathway plays an important role in the development of drug resistance, therefore, inhibition of p38 MAPK activation by the combination of IMRT followed by treatment with inhibitor for p38 MAPK can be a promising strategy for breast cancer treatment. Thus combination of IMRT exposure and treatment with SB203580 can be used for the inhibition of drug resistant breast cancer.

Low dose of arsenic trioxide inhibits multidrug resistant-related P-glycoprotein expression in human neuroblastoma cell line

This study investigated arsenic trioxide (As2O3), cisplatin (DDP) and etoposide (Vp16) on the anticancer effects and P-glycoprotein (P-gp) expression in neuroblastoma (NB) SK-N-SH cells. The potential influence of As2O3, DDP and Vp16 currently included in NB routine treatment protocols on cytotoxicity in SK-N-SH cells was measured by flow cytometry and drug half-maximal inhibitory concentration (IC50) was established. Moreover, chemotherapeutic agent-mediated changes of cellular expression levels of resistant-related P-gp, was monitored using western blotting. The data showed that As2O3, DDP and Vp16 significantly inhibited the growth and survival of the SK-N-SH cells at different concentration. Notably, the levels of apoptosis were upregulated in SK-N-SH cells with an acceleration of the exposure time and the concentration of As2O3, DDP and Vp16. As2O3, DDP and Vp16 were observed with their IC50 values on SK-N-SH cells being 3 µM, 8 and 100 µg/ml, respectively. Flow cytometry analysis showed that As2O3 at low concentrations in SK-N-SH cells led to enhanced accumulation of cell populations in G2/M phase with increasing the exposure time, and increased levels of apoptosis. In contrast, we observed that SK-N-SH cell populations arrested in S phase by DDP and Vp16. In vitro examination revealed that following pretreatment of SK-N-SH cells with As2O3, the expression of P-gp was not increased. The expression of P-gp downregulation were noted following the group treated by As2O3 at 2 and 3 µM. Exposed to As2O3 at 3 µM for 72 h, SK-N-SH cells exhibited lower expression of P-gp than 2 µM As2O3 for 72 h. In contrast, the expression of P-gp was upregulated by DDP and VP16. In summary, SK-N-SH cells were responsive to chemotherapeutic agent-induced apoptosis in a dose-dependent and time-dependent manner. In particular, ours findings showed that low dose of As2O3 markedly reduced the P-gp expression and increased apoptotic cell death in human NB cell line.

Decellularized matrices as in vitro models of extracellular matrix in tumor tissues at different malignant levels: Mechanism of 5-fluorouracil resistance in colorectal tumor cells

Chemoresistance is a major barrier for tumor chemotherapy. It is well-known that chemoresistance increases with tumor progression. Chemoresistance is altered by both genetic mutations and the alteration of extracellular microenvironment. Particularly, the extracellular matrix (ECM) is remodeled during tumor progression. Therefore, ECM remodeling is expected to cause the acquisition of chemoresistance in highly malignant tumor tissue. Here, we prepared cultured cell-derived decellularized matrices that mimic native ECM in tumor tissues at different stages of malignancy, and 5-fluorouracil (5-FU) resistance was compared among these matrices. 5-FU resistance of colorectal tumor cells increased on the matrices derived from highly malignant tumor HT-29 cells, although the resistance did not increase on the matrices derived from low malignant tumor SW480 cells and normal CCD-841-CoN cells. The resistance on HT-29 cell-derived matrices increased through the activation of Akt and the upregulation of ABCB1 and ABCC1 without cell growth promotion, suggesting that ECM remodeling plays important roles in the acquisition of chemoresistance during tumor progression. It is expected that our decellularized matrices, or "staged tumorigenesis-mimicking matrices", will become preferred cell culture substrates for in vitro analysis of comprehensive ECM roles in chemoresistance and the screening and pharmacokinetic analysis of anti-cancer drugs.

Calpain Genetic Disruption and HSP90 Inhibition Combine To Attenuate Mammary Tumorigenesis

Calpain is an intracellular Ca(2+)-regulated protease system whose substrates include proteins involved in proliferation, survival, migration, invasion, and sensitivity to therapeutic drugs. Genetic disruption of calpain attenuated the tumorigenic potential of breast cancer cells and hypersensitized cells to 17AAG, an inhibitor of the molecular chaperone HSP90. Calpain-1 or -2 overexpression rendered cells resistant to 17AAG, whereas downregulation or inhibition of calpain-1/2 led to increased cell death in multiple breast cancer cell lines, including models of HER2(+) (SKBR3) and triple-negative basal-cell-like (MDA-MB-231) breast cancer. In an MDA-MB-231 orthotopic xenograft model, calpain knockdown or 17AAG treatment independently attenuated tumor growth and metastasis, while the combination was most effective. Calpain knockdown was associated with increased 17AAG-induced degradation of the HSP90 clients cyclin D1 and AKT and multidrug resistance protein 2, which correlated with increased expression of antimitogenic p27(KIP1) and proapoptotic BIM proteins. Like other therapeutics, 17AAG can be effluxed by specific ABC transporters. Calpain expression positively correlated with the expression of P glycoprotein in mouse embryonic fibroblasts. Importantly, we show that calpain affects ABC transporter function and efflux of clinically relevant doxorubicin. These observations provide a compelling rationale for exploring the combination of calpain inhibition with new or existing cancer therapeutics.