Multidrug resistance markers P-glycoprotein, multidrug resistance protein 1, and lung resistance protein in non-small cell lung cancer: prognostic implications

Characterization of a deazaflavin analog as a potent inhibitor of multidrug resistance-associated protein 1

Selective inhibition of overexpressed ATP binding cassette (ABC) transporters is an attractive approach to enhancing the efficacy of chemotherapeutics in multidrug resistant cancers. Previously, we reported that the cancer sensitizing effect of deazaflavin analogs, an important chemotype for developing combination treatments with topoisomerase II (TOP2) poisons, is associated with increased intracellular drug accumulation. Here we report the characterization of ZW-1226, a deazaflavin analog, as a potent inhibitor of multidrug resistance-associated protein 1 (MRP1). Specifically, ZW-1226 inhibited MRP1 with a 16-fold higher potency than the most widely used positive control MK-571 in vesicular transport assay and displayed excellent selectivity indices exceeding 100 over other major ABC transporters, including P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), MRP2 and MRP3. Mechanistically, we revealed that its MRP1 inhibitory action requires the participation of GSH. In chemo-sensitization test, ZW-1226 fully reversed the MRP1-mediated drug resistance to TOP2 poisons etoposide (ETP) and doxorubicin (DOX) in H69AR cells and conferred CC50s comparable to those in the sensitive parental NCI-H69 cells. The sensitization was associated with boosted intracellular accumulation of ETP and DOX and elevated endogenous GSH. Moreover, ZW-1226 showed potential to occupy the leukotriene C4 binding site in molecular docking with bovine MRP1, presumably with the help of GSH. Lastly, ZW-1226 exhibited high tissue to plasma partitions in mice but did not alter ETP distribution to normal tissues, suggesting it could be a viable lead with desirable pharmacokinetic properties to warrant further investigation.

Borneol-modified docetaxel plus tetrandrine micelles for treatment of drug-resistant brain glioma

OBJECTIVE

Glioma is the most common and deadly primary malignant tumor in adults. Treatment outcomes are ungratified due to the presence of blood-brain barrier (BBB), glioma stem cells (GSCs) and multidrug resistance (MDR). Docetaxel (DTX) is considered as a potential drug for the treatment of brain tumor, but its effectiveness is limited by its low bioavailability and drug resistance. Tetrandrine (TET) reverses the resistance of tumor cells to chemotherapy drugs. Borneol (BO) modified in micelles has been shown to promote DTX plus TET to cross the BBB, allowing the drug to better act on tumors. Therefore, we constructed BO-modified DTX plus TET micelles to inhibit chemotherapeutic drug resistance.

SIGNIFICANCE

Provide a new treatment method for drug-resistant brain gliomas.

METHODS

In this study, BO-modified DTX plus TET micelles were prepared by thin film dispersion method, their physicochemical properties were characterized. Its targeting ability was investigated. The therapeutic effect on GSCs was investigated by in vivo and in vitro experiments.

RESULTS

The BO-modified DTX plus TET micelles were successfully constructed by thin film dispersion method, and the micelles showed good stability. The results showed that targeting micelles increased bEnd.3 uptake and helped drugs cross the BBB in vitro. And we also found that targeting micelles could inhibit cell proliferation, promote cell apoptosis and inhibit the expression of drug-resistant protein, thus provide a new treatment method for GSCs in vitro and in vivo.

CONCLUSIONS

BO-modified DTX plus TET micelles may provide a new treatment method for drug-resistant brain gliomas.

Immunofluorescence-Based Assay for High-Throughput Analysis of Multidrug Resistance Markers in Non-Small Cell Lung Carcinoma Patient-Derived Cells

Lung cancer remains the leading cause of cancer death globally, with non-small cell lung cancer (NSCLC) accounting for the majority of cases. Multidrug resistance (MDR), often caused by ATP-binding cassette (ABC) transporters, represents a significant obstacle in the treatment of NSCLC. While genetic profiling has an important role in personalized therapy, functional assays that measure cellular responses to drugs are gaining in importance. We developed an automated microplate-based immunofluorescence assay for the evaluation of MDR markers ABCB1, ABCC1, and ABCG2 in cells obtained from NSCLC patients through high-content imaging and image analysis, as part of a functional diagnostic approach. This assay effectively discriminated cancer from non-cancer cells within mixed cultures, which is vital for accurate assessment of changes in MDR marker expression in different cell populations in response to anticancer drugs. Validation was performed using established drug-sensitive (NCI-H460) and drug-resistant (NCI-H460/R) NSCLC cell lines, demonstrating the assay's capacity to distinguish and evaluate different MDR profiles. The obtained results revealed wide-ranging effects of various chemotherapeutic agents on MDR marker expression in different patient-derived NSCLC cultures, emphasizing the need for MDR diagnostics in NSCLC. In addition to being a valuable tool for assessing drug effects on MDR markers in different cell populations, the assay can complement genetic profiling to optimize treatment. Further assay adaptations may extend its application to other cancer types, improving treatment efficacy while minimizing the development of resistance.

Therapeutic Role of Alkaloids and Alkaloid Derivatives in Cancer Management

Cancer is a neoplastic disease that remains a global challenge with a reported prevalence that is increasing annually. Though existing drugs can be applied as single or combined therapies for managing this pathology, their concomitant adverse effects in human applications have led to the need to continually screen natural products for effective and alternative anticancer bioactive principles. Alkaloids are chemical molecules that, due to their structural diversity, constitute a reserve for the discovery of lead compounds with interesting pharmacological activities. Several in vitro studies and a few in vivo findings have documented various cytotoxic and antiproliferative properties of alkaloids. This review describes chaetocochin J, neopapillarine, coclaurine, reflexin A, 3,10-dibromofascaplysin and neferine, which belong to different alkaloid classes with antineoplastic properties and have been identified recently from plants. Despite their low solubility and bioavailability, plant-derived alkaloids have viable prospects as sources of viable lead antitumor agents. This potential can be achieved if more research on these chemical compounds is directed toward investigating ways of improving their delivery in an active form close to target cells, preferably with no effect on neighboring normal tissues.

P-glycoprotein and cancer: what do we currently know?

Acquired resistance during cancer treatment is unfortunately a frequent event. There are several reasons for this, including the ability of the ATP-binding cassette transporters (ABC transporters), which are integral membrane proteins, to export chemotherapeutic molecules from the interior of the tumor cells. One important member of this family is the protein known as Permeability Glycoprotein (P-Glycoprotein, P-gp or ABCB1). Its clinical relevance relies mainly on the fact that the inhibition of P-gp and other ABC transporters could result in the reversal of the multidrug resistance (MDR) phenotype in some patients. Recently, other roles apart from being a key player in MDR, have emerged for P-gp. Therefore, this review discusses the relationship between P-gp and MDR, in addition to the possible role of this protein as a biomarker in cancer.

Nanomedicine Strategies for Management of Drug Resistance in Lung Cancer

Lung cancer (LC) is one of the leading causes of cancer occurrence and mortality worldwide. Treatment of patients with advanced and metastatic LC presents a significant challenge, as malignant cells use different mechanisms to resist chemotherapy. Drug resistance (DR) is a complex process that occurs due to a variety of genetic and acquired factors. Identifying the mechanisms underlying DR in LC patients and possible therapeutic alternatives for more efficient therapy is a central goal of LC research. Advances in nanotechnology resulted in the development of targeted and multifunctional nanoscale drug constructs. The possible modulation of the components of nanomedicine, their surface functionalization, and the encapsulation of various active therapeutics provide promising tools to bypass crucial biological barriers. These attributes enhance the delivery of multiple therapeutic agents directly to the tumor microenvironment (TME), resulting in reversal of LC resistance to anticancer treatment. This review provides a broad framework for understanding the different molecular mechanisms of DR in lung cancer, presents novel nanomedicine therapeutics aimed at improving the efficacy of treatment of various forms of resistant LC; outlines current challenges in using nanotechnology for reversing DR; and discusses the future directions for the clinical application of nanomedicine in the management of LC resistance.

Circular RNAcirc_0076305 Promotes Cisplatin (DDP) Resistance of Non-Small Cell Lung Cancer Cells by Regulating ABCC1 Through miR-186-5p

Background: Lung cancer is a social problem of increasing concern, and non-small cell lung cancer (NSCLC) accounts for 80%-85% incidence of lung cancer. Cisplatin (DDP) is reported as a first-line chemotherapy drug for NSCLC, but the resistance has became a main obstacle for NSCLC treatment. The high level of circular RNA circ_0076305 was related to the DDP resistance in NSCLC. However, the mechanism of circ_0076305 remains unclear in DDP resistance of NSCLC. Materials and Methods: Exosomes were detected by a transmission electron microscope and nanoparticle tracking analysis. The protein levels of CD63, CD81, P-glycoprotein (P-gp), Lung resistance-related protein, and ATP-binding cassette subfamily C member 1 (ABCC1) were examined by Western blot assay. Circ_0076305, microRNA-186-5p (miR-186-5p), and ABCC1 levels were tested by real-time quantitative polymerase chain reaction. DDP resistance was examined by 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide assay. The binding relationship between miR-186-5p and circ_0076305 or ABCC1 was predicted by circRNA interactome or starBase, and then verified by dual-luciferase reporter and RNA immunoprecipitation assays. The effect of circ_0076305 on DDP resistance in NSCLC was examined by xenograft tumor model in vivo. Results: Circ_0076305 was increased in NSCLC cell-derived exosomes, DDP-resistant NSCLC tissues and cells. Circ_0076305 knockdown elevated DDP sensitivity in vitro. Mechanically, circ_0076305 enhanced ABCC1 expression through sponging miR-186-5p, thus regulating DDP resistance of NSCLC. Furthermore, circ_0076305 silencing improved DDP sensitivity of NSCLC in vivo. Conclusion: The results from this study disclosed that circ_0076305 knockdown improved DDP sensitivity by the miR-186-5p/ABCC1 axis in NSCLC, hinting a potential circRNA-targeted therapy for NSCLC.

Clinical applications of nanomedicines in lung cancer treatment

Lung cancer is the leading cause of cancer mortality worldwide. Owing to a lack of early-stage diagnosis, most lung cancers are detected in advanced stages, limiting the available therapeutic options. Moreover, extensive systemic chemotherapy of lung tumors is often associated with severe off-target toxicity and drug resistance of cancer cells, thus diminishing the outcomes of chemotherapy modalities. In this light, nanomedicines have opened an alternative avenue to develop more efficacious therapeutic platforms while addressing several current challenges. Clinical findings have revealed that nanomedicines improve the pharmacokinetics and biodistribution of the therapeutic agents while decreasing their systemic toxicity. This review provides an update on nanomedicines that have been clinically approved or are undergoing clinical trials for treatment of lung cancer. By discussing the clinical findings of the current nanoformulations, this review provides prospects for the development of more efficacious nanomedicines to improve the clinical outcomes of lung cancer treatment.

Targeted drug therapy in non-small cell lung cancer: Clinical significance and possible solutions-Part I

INTRODUCTION

Non-small cell lung cancer (NSCLC) comprises of 84% of all lung cancer cases. The treatment options for NSCLC at advanced stages are chemotherapy and radiotherapy. Chemotherapy involves conventional nonspecific chemotherapeutics, and targeted-protein/receptor-specific small molecule inhibitors. Biologically targeted therapies such as an antibody-based immunotherapy have been approved in combination with conventional therapeutics. Approved targeted chemotherapy is directed against the kinase domains of mutated cellular receptors such as epidermal growth factor receptor (EGFR), anaplastic lymphoma kinases (ALK), neurotrophic receptor kinases (NTRK) and against downstream signaling molecules such as BRAF (v-raf murine sarcoma viral oncogene homolog B1). Approved biologically targeted therapy involves the use of anti-angiogenesis antibodies and antibodies against immune checkpoints.

AREAS COVERED

The rationale for the employment of targeted therapeutics and the resistance that may develop to therapy are discussed. Novel targeted therapeutics in clinical trials are also included.

EXPERT OPINION

Molecular and histological profiling of a given tumor specimen to determine the aberrant onco-driver is a must before deciding a targeted therapeutic regimen for the patient. Periodic monitoring of the patients response to a given therapeutic regimen is also mandatory so that any semblance of resistance to therapy can be deciphered and the regimen may be accordingly altered.

Low dose HSP90 inhibition with AUY922 blunts rapid evolution of metastatic and drug resistant phenotypes induced by TGF-β and paclitaxel in A549 cells

OBJECTIVES

Despite advances in cancer treatment, drug resistance and metastasis continue to contribute to treatment failure. Since drug resistance and metastasis in cancer are features that often occur toward the late stages in the disease after withstanding numerous selective pressures, they may rely on a shared adaptive mechanism in order to persist. The heat shock response is one of the most well conserved adaptive responses to cellular stress found in nature. A major player in the heat shock response is HSP90, with some studies suggesting that it can facilitate the molecular evolution of drug resistance and metastasis in cancer. Non-small cell lung cancers (NSCLCs) are strongly associated with drug resistance and metastasis either at the time of diagnosis or early in the treatment process.

MATERIALS AND METHODS

We explored the role of HSP90 in the evolution of metastatic and drug resistant features in NSCLC by treating A549 cells with AUY922, a clinically relevant HSP90 inhibitor, and inducing metastatic and drug resistant phenotypes via treatment with TGF-β and paclitaxel, respectively. We measured phenotypic plasticity in E-Cadherin, a marker for epithelial to mesenchymal transition and two ABC transporters associated with drug resistant lung cancers.

RESULTS

We found that metastatic and efflux dependent drug resistant features negatively correlated with AUY922 treatment. We followed our results with functional assays relevant to metastasis and ABC transporters to confirm our results. Specifically we found the expression of E-cadherin was significantly increased in A549 cultures pretreated with AUY922 prior to exposure to paclitaxel, while expression of the drug transporters ABCB1 and ABCC1 was significantly reduced under similar conditions.

CONCLUSION

Together our data indicates that HSP90 inhibition with AUY922 can limit the acquisition of metastatic and drug resistant phenotypes in A549 cells at low, clinically appropriate doses.

Characterization of the kinetic cycle of an ABC transporter by single-molecule and cryo-EM analyses

ATP-binding cassette (ABC) transporters are molecular pumps ubiquitous across all kingdoms of life. While their structures have been widely reported, the kinetics governing their transport cycles remain largely unexplored. Multidrug resistance protein 1 (MRP1) is an ABC exporter that extrudes a variety of chemotherapeutic agents and native substrates. Previously, the structures of MRP1 were determined in an inward-facing (IF) or outward-facing (OF) conformation. Here, we used single-molecule fluorescence spectroscopy to track the conformational changes of bovine MRP1 (bMRP1) in real time. We also determined the structure of bMRP1 under active turnover conditions. Our results show that substrate stimulates ATP hydrolysis by accelerating the IF-to-OF transition. The rate-limiting step of the transport cycle is the dissociation of the nucleotide-binding-domain dimer, while ATP hydrolysis per se does not reset MRP1 to the resting state. The combination of structural and kinetic data illustrates how different conformations of MRP1 are temporally linked and how substrate and ATP alter protein dynamics to achieve active transport.

Oligomeric proanthocyanidins (OPCs) from grape seed extract suppress the activity of ABC transporters in overcoming chemoresistance in colorectal cancer cells

Multidrug resistance is a major hindrance in managing cancer. By performing a series of experiments in chemoresistant colorectal cancer cell lines, we demonstrate that oligomeric proanthocyanidins (OPCs) from grape seed extracts can sensitize both acquired (HCT116-FOr cells) and innately chemoresistant (H716 cells) cancer cells to chemotherapeutic drugs, 5-fluorouracil (5FU) and oxaliplatin, by inhibiting adenosine triphosphate-binding cassette (ABC) transporter proteins. When combined with chemotherapeutic drugs, OPCs significantly inhibited growth of the chemoresistant cells (P < 0.05 to < 0.001) and decreased the expression of several key ABC transporters. Moreover, the activity of the ABC transporters was also significantly decreased by OPCs in the cell lines (P < 0.05). We further confirmed that co-treatment with OPCs sensitized the chemoresistant cells to 5FU and oxaliplatin, as observed by improvement in cell cycle arrest, double-strand breaks and p53 accumulation in these cells. In addition, we confirmed that co-administration of OPCs with chemotherapeutic drugs significantly decreased chemoresistant xenograft tumor growth in mice (P < 0.05). Together, our study illuminates the downregulation of multiple ABC transporters as a mechanism by which OPCs overcome chemoresistance in cancer cells and may serve as adjunctive treatments in patients with refractory colorectal cancer.

Ameliorated in vitro anticancer efficacy of methotrexate d-α-Tocopheryl polyethylene glycol 1000 succinate ester against breast cancer cells

Background

Methotrexate (MTX), a folate anti-metabolite, has been used widely in the treatment of plenty of malignancies. However, the clinical use is limited because of its poor water solubility (BCS class II drug), nonspecific distribution, drug resistance, short circulation half-life, and toxicity. The objective of the present research was to synthesize the ester prodrug of MTX with d-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS) and characterize for in vitro anticancer efficacy.

Results

The FTIR and NMR results revealed the successful synthesis of the prodrug. The assay and saturation solubility of the prodrug is found to be 23 ± 2.5% and 6.7 ± 1.3 mg/mL (MTX equivalent) respectively. The CMC of the prodrug in distilled water at room temperature is found to be 36.9 ± 2.6 μg/mL. The prepared prodrug micelles showed a mean particle size of 166 ± 10 nm (PDI, 0.325 ± 0.09). Further, the TEM results confirmed the self-assembling character of the prodrug into micelles with a nearly spherical shape. The prodrug caused the significantly (p < 0.01) less hemolysis (16.8 ± 1.5%) when compared to plain MTX solution and significantly higher (p < 0.01) in vitro cytotoxicity, cell cycle arresting, and apoptosis against human breast cancer cells (MCF-7 and MDA-MB-231).

Conclusion

Our study results revealed the remarkable in vitro anticancer activity of MTX following its esterification with TPGS. However, further, in vivo studies are needed to prove its efficacy against different cancers.

Tetrandrine Interaction with ABCB1 Reverses Multidrug Resistance in Cancer Cells Through Competition with Anti-Cancer Drugs Followed by Downregulation of ABCB1 Expression

The overexpression of ABC transporters induced by anticancer drugs has been found to be the main cause of multidrug resistance. It is actually also a strategy by which cancer cells escape being killed. Tetrandrine is a natural product extracted from the stem of Tinospora crispa. In this study, tetrandrine showed synergistic cytotoxic activity in combinational use with chemotherapeutic drugs, such as Doxorubicin, Vincristine, and Paclitaxel, in both drug-induced and MDR1 gene-transfected cancer cells that over-expressed ABCB1/P-glycoprotein. Tetrandrine stimulated P-glycoprotein ATPase activity, decreased the efflux of [³H]-Paclitaxel and increased the intracellular accumulation of [³H]-Paclitaxel in KB-C2 cells. Furthermore, SW620/Ad300 and KB-C2 cells pretreated with 1 μM tetrandrine for 72 h decreased P-glycoprotein expression without changing its cellular localization. This was demonstrated through Western blotting and immunofluorescence analysis. Interestingly, down-regulation of P-glycoprotein expression was not correlated with gene transcription, as the MDR1 mRNA level exhibited a slight fluctuation in SW620/Ad300 and KB-C2 cells at 0, 24, 48, and 72 h treatment time points. In addition, molecular docking analysis predicted that tetrandrine had inhibitory potential with the ABCB1 transporter. Our results suggested that tetrandrine can antagonize MDR in both drug-selected and MDR1 gene-transfected cancer cells by down regulating the expression of the ABCB1 transporter, followed by increasing the intracellular concentration of chemotherapeutic agents. The combinational therapy using tetrandrine and other anticancer drugs could promote the treatment efficiency of drugs that are substrates of ABCB1.

Sphingosine kinase-1 predicts overall survival outcomes in non-small cell lung cancer patients treated with carboplatin and navelbine

Sphingosine 1-phosphate (S1P) is a bioactive lipid metabolite associated with cancer cell proliferation, survival, migration and regulation of tumor angiogenesis in various cellular and animal models. Sphingosine kinase-1 (SphK1) and S1P lyase are the main enzymes that respectively control the synthesis and degradation of S1P. The present study analyzed the prognostic and predictive value of SphK1 and S1P lyase expression in patients with non-small cell lung cancer (NSCLC), treated with either surgery alone or in combination with adjuvant carboplatin and navelbine. Formalin-fixed, paraffin-embedded tissue samples from 176 patients with NSCLC were stained immunohistochemically using antibodies against SphK1 and S1P lyase, and their expression was correlated with all available clinicopathological factors. Increased expression of SphK1 was significantly associated with shorter overall and disease free survival in patients treated with adjuvant platinum-based chemotherapy. No prognostic relevance for S1P lyase expression was observed. Collectively, the results suggest that the immunohistochemical detection of SphK1 may be a promising predictive marker in NSCLC patients treated with adjuvant platinum-based chemotherapy.

ATP binding cassette subfamily B member 9 (ABCB9) is a prognostic indicator of overall survival in ovarian cancer

Ovarian cancer (OC) is one of the most common gynecological malignancies and owns the highest mortality rate among all gynecological malignant tumors. ATP binding cassette subfamily B member 9 (ABCB9) is an antigen processing-like (TAPL) transporter that has been found to be involved in the development and progression of various malignant tumors in accumulating reports. However, the potential role of ABCB9 in OC has never been reported.In this study, ABCB9 expression was evaluated in normal ovarian tissues and ovarian cancer tissues using The Cancer Genome Atlas (TCGA) database. And the associations between ABCB9 expression and clinical parameters of patients of OC were evaluated by Chi-square tests. Kaplan-Meier analysis and Cox regression analysis were performed to evaluate the prognostic significance of ABCB9. GSEA was performed to explore related signaling pathway.ABCB9 expression levels were significantly decreased in OC compared with normal ovarian tissues (P < .001). Low ABCB9 expression was associated with survival status (P = .0148) in OC. Kaplan-Meier analysis showed that low ABCB9 expression was associated with poor overall survival in OC (P = .0032). Multivariable Cox regression analysis indicated that low ABCB9 expression was an independent prognostic factor (HR 0.64; P = .01) in OC patients. Besides, epithelial mesenchymal transition, UV response, and TGF-β signaling were enriched in low ABCB9 expression phenotype, respectively, examined by gene set enrichment analysis.These results suggest that ABCB9 is an independent prognostic indicator in OC with certain clinical significance.

Proteins Regulating Microvesicle Biogenesis and Multidrug Resistance in Cancer

Microvesicles (MV) are emerging as important mediators of intercellular communication. While MVs are important signaling vectors for many physiological processes, they are also implicated in cancer pathology and progression. Cellular activation is perhaps the most widely reported initiator of MV biogenesis, however, the precise mechanism remains undefined. Uncovering the proteins involved in regulating MV biogenesis is of interest given their role in the dissemination of deleterious cancer traits. MVs shed from drug-resistant cancer cells transfer multidrug resistance (MDR) proteins to drug-sensitive cells and confer the MDR phenotype in a matter of hours. MDR is attributed to the overexpression of ABC transporters, primarily P-glycoprotein and MRP1. Their expression and functionality is dependent on a number of proteins. In particular, FERM domain proteins have been implicated in supporting the functionality of efflux transporters in drug-resistant cells and in recipient cells during intercellular transfer by vesicles. Herein, the most recent research on the proteins involved in MV biogenesis and in the dissemination of MV-mediated MDR are discussed. Attention is drawn to unanswered questions in the literature that may prove to be of benefit in ongoing efforts to improve clinical response to chemotherapy and circumventing MDR.

Overcoming multidrug resistance through inhalable siRNA nanoparticles-decorated porous microparticles based on supercritical fluid technology

BACKGROUND

In recent times, the co-delivery therapeutics have garnered enormous interest from researchers in the treatment of cancers with multidrug resistance (MDR) due to their efficient delivery of multiple agents, which result in synergistic effects and capable of overcoming all the obstacles of MDR in cancer. However, an efficient delivery platform is required for the conveyance of diverse agents that can successfully devastate MDR in cancer.

METHODS

Initially, short-interfering RNA-loaded chitosan (siRNA-CS) nanoparticles were synthesized using the ionic gelation method. Further, the siRNA-CS nanoparticles and doxorubicin hydrochloride (DOX) were co-loaded in poly-L-lactide porous microparticles (PLLA PMs) (nano-embedded porous microparticles, [NEPMs]) by the supercritical anti-solvent (SAS) process.

RESULTS AND DISCUSSION

The NEPM formulation exhibited an excellent aerodynamic performance and sustained release of DOX, which displayed higher anticancer efficacy in drug-resistant cells (human small cell lung cancer, H69AR cell line) than those treated with either free DOX and DOX-PLLA PMs due to the siRNA from CS nanoparticles silenced the MDR gene to DOX therapy.

CONCLUSION

This eco-friendly process provides a convenient way to fabricate such innovative NEPMs co-loaded with a chemotherapeutic agent and a gene, which can devastate MDR in cancer through the co-delivery system.

ATP-binding cassette transporters in progression and clinical outcome of pancreatic cancer: What is the way forward?

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive diseases and is characterized by high chemoresistance, leading to the lack of effective therapeutic approaches and grim prognosis. Despite increasing understanding of the mechanisms of chemoresistance in cancer and the role of ATP-binding cassette (ABC) transporters in this resistance, the therapeutic potential of their pharmacological inhibition has not been successfully exploited yet. In spite of the discovery of potent pharmacological modulators of ABC transporters, the results obtained in clinical trials have been so far disappointing, with high toxicity levels impairing their successful administration to the patients. Critically, although ABC transporters have been mostly studied for their involvement in development of multidrug resistance (MDR), in recent years the contribution of ABC transporters to cancer initiation and progression has emerged as an important area of research, the understanding of which could significantly influence the development of more specific and efficient therapies. In this review, we explore the role of ABC transporters in the development and progression of malignancies, with focus on PDAC. Their established involvement in development of MDR will be also presented. Moreover, an emerging role for ABC transporters as prognostic tools for patients' survival will be discussed, demonstrating the therapeutic potential of ABC transporters in cancer therapy.

"Keaping" a lid on lung cancer: the Keap1-Nrf2 pathway

Lung cancer remains one of the world's deadliest cancers, with effective targeted treatment options available for only a small subset of patients. The rapid expansion of cancer genomics in recent years has provided insight into the genetic landscape of all major lung cancer subtypes and led to new discoveries on the heterogeneous biology underlying lung tumorigenesis. Interestingly, these studies have revealed a high frequency of alterations in the Kelch-like ECG-associated protein 1 (KEAP1)-Nuclear factor erythoid-2-related factor 2 (NRF2) stress response pathway, for which no targeted treatments are currently available. In this review, we describe the molecular mechanisms underlying NRF2 pathway activation in lung cancer cells, with a focus on in vivo functional studies in genetically engineered mouse models. Importantly, potential avenues and implications for therapeutic targeting of KEAP1-NRF2 pathway vulnerabilities for lung cancer patients will be highlighted.

Prognostic role of multidrug resistance-associated protein 1 expression and platelet count in operable non-small cell lung cancer

The overall survival rate of patients with non-small cell lung cancer (NSCLC) following resection remains poor due to the high rates of recurrence and metastasis. The investigation of novel biomarkers is clinically necessary to improve treatment strategies. Multidrug resistance-associated protein 1 (MRP1) and platelet count are linked to a poor prognosis in various types of cancer. However, it is unknown whether MRP1 or platelet count is a suitable prognostic indicator of NSCLC. In the present study, 427 patients with operable NSCLC were enlisted. The association of MRP1 expression and platelet count with clinical pathological factors and patient outcome was evaluated. MRP1 expression was found to be significantly associated with sex, histological type and tumor differentiation, while platelet count was significantly associated with smoking behavior, histological type and clinical stage. Platelet count was significantly higher in patients with negative MRP1 expression than in those with positive MRP1 expression. Survival analysis indicated that there was no association between MRP1 expression and disease-free survival (DFS) or overall survival (OS) time. In the patients with no lymph node metastasis, the OS time was significantly longer in patients with positive MRP1 expression than in those with negative expression. However, in the patients with lymph node metastasis, the DFS time was significantly shorter in patients with positive MRP1 expression than in those with negative expression. There was an association between the platelet count and DFS and OS times, which were significantly longer in patients with a normal platelet count than in those with thrombocytosis. In conclusion, MRP1 expression and platelet count are valuable independent prognostic biomarkers for survival in operable NSCLC.

Acquired nintedanib resistance in FGFR1-driven small cell lung cancer: role of endothelin-A receptor-activated ABCB1 expression

Genomically amplified fibroblast growth factor receptor 1 (FGFR1) is an oncogenic driver in defined lung cancer subgroups and predicts sensibility against FGFR1 inhibitors in this patient cohort. The FGFR inhibitor nintedanib has recently been approved for treatment of lung adenocarcinoma and is currently evaluated for small cell lung cancer (SCLC). However, tumor recurrence due to development of nintedanib resistance might occur. Hence, we aimed at characterizing the molecular mechanisms underlying acquired nintedanib resistance in FGFR1-driven lung cancer. Chronic nintedanib exposure of the FGFR1-driven SCLC cell line DMS114 (DMS114/NIN) but not of two NSCLC cell lines induced massive overexpression of the multidrug-resistance transporter ABCB1. Indeed, we proved nintedanib to be both substrate and modulator of ABCB1-mediated efflux. Importantly, the oncogenic FGFR1 signaling axis remained active in DMS114/NIN cells while bioinformatic analyses suggested hyperactivation of the endothelin-A receptor (ET_AR) signaling axis. Indeed, ET_AR inhibition resensitized DMS114/NIN cells against nintedanib by downregulation of ABCB1 expression. PKC and downstream NFκB were identified as major downstream players in ET_AR-mediated ABCB1 hyperactivation. Summarizing, ABCB1 needs to be considered as a factor underlying nintedanib resistance. Combination approaches with ET_AR antagonists or switching to non-ABCB1 substrate FGFR inhibitors represent innovative strategies to manage nintedanib resistance in lung cancer.

Combining GRP78 suppression and MK2206-induced Akt inhibition decreases doxorubicin-induced P-glycoprotein expression and mitigates chemoresistance in human osteosarcoma

P-glycoprotein (P-gp) overexpression is associated with poor prognosis and drug-resistance in osteosarcoma (OS), but the underlying mechanisms remain incompletely understood. Here, we examined the regulation of P-gp, GRP78, and phospho-Akt in doxorubicin (DOX)-treated OS cells. DOX induced P-gp expression, which was associated with increased GRP78 levels and Akt activation in vitro and in vivo. Functional analysis showed that Akt induces P-gp and GRP78 expression, which contributes to the DOX-induced Akt activation. Examination of the relationship between Akt and GRP78 demonstrated that GRP78 suppression attenuates the Akt activity in OS parental sensitive and resistant cells, indicating that GRP78 is required for full Akt activity. Inhibition of Akt activity using MK2206 decreased GRP78 expression in OS cells, which enhanced the inhibitory effect of MK2206 on P-gp expression. GRP78 knockdown combined with MK2206 suppressed the development of DOX resistance in OS cells and inhibited the in vivo tumor growth in the presence of DOX. These results support the development of novel therapeutic strategies that target GRP78 and Akt to sensitize OS cells for chemotherapy.

Expression of MRP1, BCRP, LRP and ERCC1 as prognostic factors in non-small cell lung cancer patients receiving postoperative cisplatin-based chemotherapy

The development of resistance to chemotherapy is one of the major obstacles in the treatment of non-small cell lung cancer (NSCLC). The purpose of this study was to investigate the prognostic value of multidrug resistance protein 1 (MRP1), breast cancer resistance protein (BCRP), lung resistance-related protein (LRP), and excision repair cross-complementing 1 (ERCC1) in NSCLC patients receiving cisplatin-based adjuvant chemotherapy (cisplatin plus vinorelbine or gemcitabine) after tumor resection. We used semiquantitative reverse-transcription polymerase chain reaction to detect the expression of MRP1, BCRP, LRP and ERCC1 mRNA in surgical resection specimens of 60 patients with stage IB through IIIA NSCLC. The expression level of each gene was analyzed in relation to clinicopathological factors, tumor-free survival (TFS), and overall survival. The results showed that stage IIIA (p=0.011), N1 and N2 status (p=0.008), high expression of MRP1 (p=0.034) and LRP (p=0.018) were associated with shorter TFS. Stage IIIA (p=0.0105), N1 and N2 status (p=0.009), high expression of MRP1 (p=0.021) and ERCC1 (p=0.012) were related to a shorter overall survival. Cox multivariate analyses revealed that early stage (p=0.013 and p=0.024), negative lymph node status (p=0.006 and p=0.011), and low MRP1 expression (p=0.022 and p=0.035) were independent predictors of favorable TFS and overall survival, respectively. Additionally, ERCC1 (p=0.019) was an independent predictor of favorable overall survival.

ATP Binding Enables Substrate Release from Multidrug Resistance Protein 1

The multidrug resistance protein MRP1 is an ATP-driven pump that confers resistance to chemotherapy. Previously, we have shown that intracellular substrates are recruited to a bipartite binding site when the transporter rests in an inward-facing conformation. A key question remains: how are high-affinity substrates transferred across the membrane and released outside the cell? Using electron cryomicroscopy, we show here that ATP binding opens the transport pathway to the extracellular space and reconfigures the substrate-binding site such that it relinquishes its affinity for substrate. Thus, substrate is released prior to ATP hydrolysis. With this result, we now have a complete description of the conformational cycle that enables substrate transfer in a eukaryotic ABC exporter.

Schisandrin A reverses doxorubicin-resistant human breast cancer cell line by the inhibition of P65 and Stat3 phosphorylation

BACKGROUND

Multidrug resistance (MDR) in breast cancer therapy occurs frequently. Thus, anti-MDR agents from natural products or synthetic compounds were tested extensively. We have also explored the reverse effect and mechanism of Schisandrin A (Sch A), a natural product, on MCF-7 breast cancer doxorubicin (DOX)-resistant subline MCF-7/DOX.

METHODS

MTT assay was performed to measure the viability of MCF-7 cells to assess the reverse effect of Sch A. Western blot analysis was used to study the protein levels. Laser scanning confocal microscopy was performed to detect the intercellular DOX and Rhodamine 123 accumulation. The qRT-PCR was used to analysis the target gene expression. Dual-luciferase reporter assay was performed to test the transcriptional activity of P-glycoprotein (P-gp).

RESULTS

Sch A, at the concentration of 20 µM, showed selective reverse effect (better than the positive control, verapamil at 5 µM) on MCF-7/DOX cell line but not on BEL-7402/DOX, Hep G2/DOX, and K-562/DOX cells. In addition, Sch A enhanced DOX-induced cleavage of Caspase-9 and PARP levels by increasing intracellular DOX accumulation and inhibiting P-gp function. Furthermore, Sch A selectively suppressed P-gp at gene and protein levels in MCF-7/DOX cells which express high level of MDR1 but not MRP1, MRP3, or BCRP. Besides, Sch A showed inhibitory effect on P-gp transcriptional activity. Sch A significantly reduced p-IκB-α (Ser32) and p-Stat3 (Tyr705) levels which mediate P-gp expression. In addition, Stat3 knockdown enhanced the reverse effect of siP65. The combined effect of siStat3 and siP65 was better than Sch A single treatment in MCF-7/DOX cells.

CONCLUSION

Sch A specifically reverses P-gp-mediated DOX resistance in MCF-7/DOX cells by blocking P-gp, NF-κB, and Stat3 signaling. Inhibition of P65 and Stat3 shows potent anti-MDR effect on MCF-7/DOX cells.

MEK inhibitor enhances sensitivity to chemotherapeutic drugs in multidrug resistant hepatocellular carcinoma cells

The aim of the present study was to investigate the association between the mitogen-activated protein kinase (MAPK) signal transduction pathway and multidrug resistance in hepatocellular carcinoma cells. A Cell Counting Kit-8 assay was used to determine the drug sensitivity of HepG2 and HepG2/ADM hepatocellular carcinoma cell lines in combination with the MAPK/extracellular-signal-regulated kinase kinase (MEK) inhibitor U0126. Flow cytometry was used to analyze the rate of apoptosis. The reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to determine P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) mRNA expression following treatment with various concentrations of U0126. P-gp and MRP1 expression levels were measured using Western blot analysis. The half-maximal inhibitory concentration was markedly decreased in combination with U0126. RT-qPCR results demonstrated that the expression of multidrug resistance 1 (MDR1) and MRP1 in HepG2/ADM cells was increased 5.37- and 6-14-fold compared with that in HepG2 cells. Furthermore, the expression levels in HepG2/ADM cells were decreased following U0126 treatment in a dose-dependent manner. The expression of P-gp and MRP1 in HepG2/ADM cells was increased 2.68- and 2.76-fold compared with that in HepG2 cells. Furthermore, the expression levels in HepG/ADM cells were decreased following U0126 treatment in a dose-dependent manner. The results of the present study indicate that the MEK inhibitor U0126 enhances sensitivity to chemotherapeutic drugs by downregulating P-gp and MRP1 expression in resistant hepatocellular carcinoma cells. The combination of MEK inhibitor and conventional chemotherapeutic drugs may provide novel therapeutic prospects for the treatment of drug-resistant hepatocellular carcinoma.

Simultaneous delivery of Paclitaxel and Bcl-2 siRNA via pH-Sensitive liposomal nanocarrier for the synergistic treatment of melanoma

pH-sensitive drug carriers that are sensitive to the acidic (pH = ~6.5) microenvironments of tumor tissues have been primarily used as effective drug/gene/siRNA/microRNA carriers for releasing their payloads to tumor cells/tissues. Resistance to various drugs has become a big hurdle in systemic chemotherapy in cancer. Therefore delivery of chemotherapeutic agents and siRNA's targeting anti apoptotic genes possess advantages to overcome the efflux pump mediated and anti apoptosis-related drug resistance. Here, we report the development of nanocarrier system prepared from kojic acid backbone-based cationic amphiphile containing endosomal pH-sensitive imidazole ring. This pH-sensitive liposomal nanocarrier effectively delivers anti-cancer drug (Paclitaxel; PTX) and siRNA (Bcl-2), and significantly inhibits cell proliferation and reduces tumor growth. Tumor inhibition response attributes to the synergistic effect of PTX potency and MDR reversing ability of Bcl-2 siRNA in the tumor supporting that kojic acid based liposomal pH-sensitive nanocarrier as efficient vehicle for systemic co-delivery of drugs and siRNA.

Pharmacogenetic analysis of advanced non-small-cell lung cancer patients treated with first-line paclitaxel and carboplatin chemotherapy

BACKGROUND

Genetic polymorphisms contribute toward interindividual variations in drug response. We investigated the effects of genetic polymorphisms on the clinical outcome of advanced non-small-cell lung cancer patients with first-line paclitaxel and carboplatin.

MATERIALS AND METHODS

A total of 194 non-small-cell lung cancer patients were prospectively enrolled from January 2010 to January 2013. We genotyped 11 polymorphisms in seven genes involved in the glycolysis pathway and the related pharmacokinetic/pharmacodynamic pathway. Genetic associations with PET-SUV, survival outcome, and toxicity were analyzed, and in-vitro drug transport activity was measured in the oocyte system.

RESULTS

Patients with the c.334 T>G and c.699 G>A homozygous variant in SLCO1B3 showed a higher incidence of grade 3/4 anemia (P=0.002). Transport activities of oocyte that overexpress the SLCO1B3 c.699 G>A variant showed a significantly decreased uptake of paclitaxel compared with the wild-type expressing oocytes. In addition, patients with GG/GA/AA genotypes of ABCB1, c.2677 T>G/A locus showed inferior progression-free survival (hazard ratio=1.49, P=0.017) compared with other genotypes. The GA genotype of HIF1A, c.1834 G>A locus was associated with inferior progression-free survival compared with the GG genotype (hazard ratio=2.47, P=0.008).

CONCLUSION

This study showed that the SLCO1B3 c.699 G>A polymorphism may predict anemia and ABCB1, HIF1A polymorphism are highly predictive for worse survival in advanced NSCLC with first-line paclitaxel and carboplatin.

Secreted primary human malignant mesothelioma exosome signature reflects oncogenic cargo

Malignant mesothelioma (MM) is a highly-aggressive heterogeneous malignancy, typically diagnosed at advanced stage. An important area of mesothelioma biology and progression is understanding intercellular communication and the contribution of the secretome. Exosomes are secreted extracellular vesicles shown to shuttle cellular cargo and direct intercellular communication in the tumour microenvironment, facilitate immunoregulation and metastasis. In this study, quantitative proteomics was used to investigate MM-derived exosomes from distinct human models and identify select cargo protein networks associated with angiogenesis, metastasis, and immunoregulation. Utilising bioinformatics pathway/network analyses, and correlation with previous studies on tumour exosomes, we defined a select mesothelioma exosomal signature (mEXOS, 570 proteins) enriched in tumour antigens and various cancer-specific signalling (HPGD/ENO1/OSMR) and secreted modulators (FN1/ITLN1/MAMDC2/PDGFD/GBP1). Notably, such circulating cargo offers unique insights into mesothelioma progression and tumour microenvironment reprogramming. Functionally, we demonstrate that oncogenic exosomes facilitate the migratory capacity of fibroblast/endothelial cells, supporting the systematic model of MM progression associated with vascular remodelling and angiogenesis. We provide biophysical and proteomic characterisation of exosomes, define a unique oncogenic signature (mEXOS), and demonstrate the regulatory capacity of exosomes in cell migration/tube formation assays. These findings contribute to understanding tumour-stromal crosstalk in the context of MM, and potential new diagnostic and therapeutic extracellular targets.

Efficacy of tamoxifen in combination with docetaxel in patients with advanced non-small-cell lung cancer pretreated with platinum-based chemotherapy

The aim of this study was to evaluate the efficacy and safety of the combination of docetaxel (TXT) plus tamoxifen (TAM) in advanced non-small-cell lung cancer (NSCLC) patients who had received platinum-based first-line chemotherapy. A total of 120 advanced NSCLC patients pretreated with platinum-based chemotherapy were randomized into two treatment groups (the TXT and TXT+TAM groups) in a 1 : 1 ratio. Reversal of P-glycoprotein (P-gp) expression, tumor response, progression-free survival, overall survival, and safety were evaluated on an intention-to-treat basis. The median number of cycles of allocated chemotherapy was four in each treatment group (range: 2-6 cycles). The overall response rate and disease control rate in the TXT+TAM group were significantly higher than those in the TXT group (36.7 vs. 15.0% for overall response rate, P=0.007; 85.0 vs. 68.3% for disease control rate, P=0.031). The combination of TXT and TAM could effectively reverse P-gp expression in tumor tissues and provide a significant survival benefit for advanced NSCLC patients compared with TXT alone (11.6 vs. 9.1 months, P=0.030). In addition, in the TXT+TAM group, patients achieving P-gp reversal had a significantly greater median progression-free survival and overall survival than nonreversal patients. Furthermore, the combined therapy showed a safety profile comparable to that of TXT. The combination of TXT and TAM may be an effective and safe treatment option for advanced NSCLC patients who have already developed P-gp-mediated multidrug resistance.

Efficacy of Aidi Injection () on overexpression of P-glycoprotein induced by vinorelbine and cisplatin regimen in patients with non-small cell lung cancer

OBJECTIVE

To investigate the efficacy of Aidi Injection () on overexpression of P-glycoprotein (P-gp) induced by vinorelbine and cisplatin (NP) regimen in patients with non-small cell lung cancer (NSCLC), and study the difference between intravenous administration and targeting intratumor administration of Aidi Injection with thoracoscope.

METHODS

Totally 150 patients with NSCLC were randomly assigned to the control group, the intravenous group and the intratumor group by the random envelope method, 50 cases in each group. The patients were treated with NP regimen (2 cycles), NP regimen (2 cycles) plus Aidi intravenous injection, or NP regimen (2 cycles) plus Aidi intratumor injection with thoracoscope, respectively for 6 weeks. The clinical effificacy was observed based on Response Evaluation Criteria in Solid Tumors (RECIST) rules, the expression of P-gp in the tumor tissue was tested before, 3 and 6 weeks after treatment, the safety was evaluated by monitoring the toxicity in the process of treatment, and the progression-free survival (PFS) was measured.

RESULTS

Fifteen cases dropped out because of the irreconcilable conditions which had no relationship with the treatment, 4 in the control group, 5 in the intravenous group, and 6 in the intratumor group, respectively. Compared with the control group, the response rates (complete remission + partial response) and the disease control rates (complete remission + partial response + stable disease) were significantly higher, the P-gp expressions were significantly decreased after 3 and 6 weeks of treatment, and the Kaplan-Meier survival curves of PFS were significantly longer in the intravenous and intratumor groups (P<0.05 or P<0.01), and the intratumor group showed better effects than the intravenous group (P<0.05 or P<0.01). Compared with the control group, the occurrences of rash, nausea and leukocytopenia were signifificantly decreased in the intravenous and intratumor groups (P<0.05), but without signifificant difference between the intravenous and intratumor groups (P>0.05).

CONCLUSION

Aidi Injection not only improves the effificacy of NP regime, but also has the function of reducing adverse events and preventing against overexpression of P-gp induced by chemotherapy of NP regimen.

Regulation of Mucin 1 and multidrug resistance protein 1 by honokiol enhances the efficacy of doxorubicin-mediated growth suppression in mammary carcinoma cells

Understanding the link between chemoresistance and cancer progression may identify future targeted therapy for breast cancer. One of the mechanisms by which chemoresistance is attained in cancer cells is mediated through the expression of multidrug resistance proteins (MRPs). Acquiring drug resistance has been correlated to the emergence of metastasis, accounting for the progression of the disease. One of the diagnostic markers of metastatic progression is the overexpression of a transmembrane protein called Mucin 1 (MUC1) which has been implicated in reduced survival rate. The objective of this study was to understand the relationship between MUC1 and MRP1 using natural phenolic compound isolated from Magnolia grandiflora, honokiol, in mammary carcinoma cells. We provide evidence that honokiol suppresses the expression level of MUC1 and MRP1 in mammary carcinoma cells. In a time-dependent manner, honokiol-mediated reduction of MUC1 is followed by a reduction of MRP1 expression in the breast cancer cells. Additionally, silencing MUC1 suppresses the expression level of MRP1 and enhances the efficacy of doxorubicin, an MRP1 substrate. Taken together, these findings suggest MUC1 regulates the expression of MRP1 and provides a direct link between cancer progression and chemoresistance in mammary carcinoma cells.

In Vivo Biodistribution and Anti-Tumor Efficacy Evaluation of Doxorubicin and Paclitaxel-Loaded Pluronic Micelles Decorated with c(RGDyK) Peptide

The treatment of squamous carcinoma, especially multidrug resistance (MDR) tumors, represents one of the most formidable challenges in oncology. In this study, integrin-mediated Pluronic-based micellar system (c(RGDyK)-FP-DP) was proposed as a drug delivery system to enhance the in vivo anti-tumor efficacy in MDR human squamous carcinoma (KBv)-bearing. Following the recognition by integrin proteins express on the cell surface, cellular uptake and in vitro anti-tumor efficacy of c(RGDyK)-FP-DP were better than conventional PF-DP in KBv cells. The tumor homing specificity and further in vivo anticancer efficacy of c(RGDyK)-FP-DP were performed using subcutaneous KBv tumor-bearing mice model, respectively. Compared with PF-DP, c(RGDyK)-FP-DP demonstrated more drug accumulation in tumor and relatively less drug accumulation in heart, and an extended median survival time in the KBv tumor-bearing mice model. Furthermore, preliminary in vivo subacute toxicity evaluation was also conducted by the measurement of histopathology, blood cell counts and clinical biochemistry parameters. Results showed that no obvious toxicity was observed to the hematological system or heart after a series of intravenous administration of c(RGDyK)-FP-DP. In conclusion, our results suggested that c(RGDyK) peptide conjugated Pluronic micelles could be a promising vehicle for enhancing the treatment of MDR human squamous carcinoma.

Nuclear Multidrug Resistance-Related Protein 1 Is Highly Associated with Better Prognosis of Human Mucoepidermoid Carcinoma through the Suppression of Cell Proliferation, Migration and Invasion

Objectives

Multidrug resistance-related protein 1 (MRP1) overexpression is a well acknowledged predictor of poor response to chemotherapy, but MRP1 also correlated to better prognosis in some reports, especially for patients not pretreated with chemotherapy. In our previous study, we found nuclear translocation of MRP1 in mucoepidermoid carcinoma (MEC) for the first time. The purpose of this study was to further investigate the function of nuclear MRP1 in MEC.

Materials and Methods

Human MEC tissue samples of 125 patients were selected and stained using immunohistochemistry. The expression level of total MRP1/nuclear MRP1 of each sample was evaluated by expression index (EI) which was scored using both qualitative and quantitative analysis. The correlations between the clinicopathologic parameters and the EI of nuclear MRP1 were analyzed using Spearman’s rank correlation analysis, respectively. The effects of RNAi-mediated downregulation of nuclear MRP1 on MEC cells were assessed using flow cytometric analysis, MTT assay, plate colony formation assay, transwell invasion assay and monolayer wound healing assay.

Results

In this study, we found the EI of nuclear MRP1 was negatively correlated to the pathologic grading (r = -0.498, P<0.01) / clinical staging (r = -0.41, P<0.01) / tumor stage (r = -0.28, P = 0.02) / nodal stage (r = -0.29, P<0.01) of MEC patients. The RNAi-mediated downregulation of nuclear MRP1 further proved that the downregulation of nuclear MRP1 could increase the cell replication, growth speed, colony formation efficiency, migration and invasion ability of MEC cells.

Conclusion

Our results suggested that nuclear MRP1 is highly associated with better prognosis of human mucoepidermoid carcinoma and further study of its function mechanism would provide clues in developing new treatment modalities of MEC.

Alpinetin inhibits lung cancer progression and elevates sensitization drug-resistant lung cancer cells to cis-diammined dichloridoplatium

OBJECTIVE

Alpinetin is a novel flavonoid that has demonstrated potent antitumor activity in previous studies. However, the efficacy and mechanism of alpinetin in treating lung cancer have not been determined.

METHODS

We evaluated the impact of different doses and durations of alpinetin treatment on the cell proliferation, the apoptosis of lung cancer cells, as well as the drug-resistant lung cancer cells.

RESULTS

This study showed that the alpinetin inhibited the cell proliferation, enhanced the apoptosis, and inhibited the PI3K/Akt signaling in lung cancer cells. Moreover, alpinetin significantly increased the sensitivity of drug-resistant lung cancer cells to the chemotherapeutic effect of cis-diammined dichloridoplatium. Taken together, this study demonstrated that alpinetin significantly suppressed the development of human lung cancer possibly by influencing mitochondria and the PI3K/Akt signaling pathway and sensitized drug-resistant lung cancer cells.

CONCLUSION

Alpinetin may be used as a potential compound for combinatorial therapy or as a complement to other chemotherapeutic agents when multiple lines of treatments have failed to reduce lung cancer.

Prognostic implications of survivin and lung resistance protein in advanced non-small cell lung cancer treated with platinum-based chemotherapy

Platinum-based chemotherapy is the first-line treatment for non-small cell lung cancer (NSCLC), but the chemotherapy often results in the development of chemoresistance. The present study aimed to explore the prognostic implications of survivin and lung resistance protein (LRP) in advanced NSCLC treated with platinum-based chemotherapy. Tumor samples were collected from 61 hospitalized patients with stage IIIB-IV NSCLC that underwent platinum-based chemotherapy. All patient samples were collected in the Oncology Department of the Third Affiliated Hospital of Guangxi Medical University between January 2006 and January 2011. Cytoplasmic survivin and LRP expression were evaluated using immunohistochemistry. The expression of LRP and survivin reached 77% (47/61) and 76% (45/61), respectively. Positive expression of survivin was associated with a lower median progression-free survival (PFS) time (4 vs. 9 months; P=0.038) and a lower median overall survival (OS) time compared with the absence of survivin expression (9 vs. 16 months; P=0.039). Patients with LRP and survivin expression (n=41) demonstrated a median PFS time of 4 months. However, patients with either LRP or survivin expression (n=10) demonstrated a median PFS time of 8 months, which is similar to the median PFS time of the 10 patients with no expression of LRP and survivin (9 months; P=0.022). Either the expression of survivin or the combined expression of LRP and survivin is associated with a poor prognosis in advanced NSCLC treated with platinum-based chemotherapy.

MRP1 and its role in anticancer drug resistance

The phenomenon of multidrug resistance (MDR) in cancer is associated with the overexpression of the ATP-binding cassette (ABC) transporter proteins, including multidrug resistance-associated protein 1 (MRP1) and P-glycoprotein. MRP1 plays an active role in protecting cells by its ability to efflux a vast array of drugs to sub-lethal levels. There has been much effort in elucidating the mechanisms of action, structure and substrates and substrate binding sites of MRP1 in the last decade. In this review, we detail our current understanding of MRP1, its clinical relevance and highlight the current environment in the search for MRP1 inhibitors. We also look at the capacity for the rapid intercellular transfer of MRP1 phenotype from spontaneously shed membrane vesicles known as microparticles and discuss the clinical and therapeutic significance of this in the context of cancer MDR.

Inhibition of microvesiculation sensitizes prostate cancer cells to chemotherapy and reduces docetaxel dose required to limit tumor growth in vivo

Microvesicles shed from cells carry constituents of the cell cytoplasm, including, of importance in multidrug resistance to cancer chemotherapy, drugs that the tumor cell attempts to efflux. To see whether such drugs could be used at lower concentrations with the same efficacy, it was first shown that microvesiculation of prostate cancer (PCa) cells, PC3, could be inhibited pharmacologically with calpeptin (calpain inhibitor) and by siRNA (CAPNS1). In cells treated with docetaxel (DTX), this inhibition resulted in a third-fold increase in intracellular concentrations of DTX. As a result, 20-fold lower concentrations of DTX (5 nM) could be used, in the presence of calpeptin (20 μM) inducing the same degree of apoptosis after 48 h in PC3 cells, as 100 nM of DTX alone. Inhibition of microvesiculation similarly improved combination chemotherapy (DTX and methotrexate). In a mouse xenograft model of PCa, DTX (0.1 mg/kg) together with calpeptin (10 mg/kg), administered i.p., significantly reduced tumor volumes compared to DTX alone (0.1 mg/kg) and brought about the same reductions in tumor growth as 10 mg/kg of DTX alone. As well as further reducing vascularization, it also increased apoptosis and reduced proliferation of PC3 cells in tumor xenografts.

Adding vitamin E-TPGS to the formulation of Genexol-PM: specially mixed micelles improve drug-loading ability and cytotoxicity against multidrug-resistant tumors significantly

Genexol-PM, produced by Samyang Company (Korea) is an excellent preparation of paclitaxel (PTX) for clinical cancer treatment. However, it cannot resolve the issue of multidrug resistance (MDR)—a significant problem in the administration of PTX to cancer patients. To increase the efficacy of Genexol-PM against MDR tumors, a mixed micelle capable of serving as a vehicle for PTX was developed, and two substances were chosen as carrier materials: 1) Polyethylene glycol–polylactic acid (PEG-PLA), the original vehicle of Genexol-PM. 2) Vitamin E-TPGS, an inhibitor of P-glycoprotein (P-gp). P-gp has been proven to be the main cause of MDR. In vitro evaluation indicated that the mixed micelle was an ideal PTX delivery system for the treatment of MDR tumors; the mixed micelle also showed a significantly better drug-loading coefficient than Genexol-PM.

Bronchial-pulmonary adenocarcinoma subtyping relates with different molecular pathways

Lung cancer is one of the most common cancers in the world with a high mortality rate. We analyzed 45 surgical samples of the adenocarcinoma, 13 with lymph node metastasis. APC, BCL2, chromogranin A, CK 5/6/18 (LP34), CK20, CK7, cyclin D1, EGFR, ERCC1, HER2, Ki67, LRP, MRP, P53, RB and TTF1 expressions were evaluated by immunohistochemistry (IHC). Higher Ki67, APC, ERCC1 expressions and lower TTF1 expression were identified in advanced stages (IIA and IIIA) of adenocarcinomas, which reflect a more aggressive, less differentiated, possibly a non-TRU adenocarcinoma. Acinar, micropapillary and BA/lepidic adenocarcinoma patterns were the most similar patterns and papillary was the most different pattern followed by solid pattern, according to expression of these markers. Different adenocarcinoma patterns are engaged with different molecular pathways for carcinogenesis, based on the differences of expression. Acinar, BA/lepidic and micropapillary showed higher TTF1 expression (type TRU), and papillary and solid patterns revealed less TTF1 expression, exhibiting a non-TRU/bronchial phenotype. Solid pattern revealed lower HER2 and higher EGFR and ERCC1 (this compared to papillary) expression; papillary higher HER2 and lower ERCC1 expressions; micropapillary higher RB expression; and acinar lower ERCC1 and higher EGFR expressions. Ciclin D1 seems to have more importance in acinar and BA/lepidic patterns than in micropapillary. ERCC1 protein expression in micropapillary, solid and BA/lepidic patterns may indicate DNA repair activation. Inhibition of apoptosis could be explained by BCL2 overexpression, present in all adenocarcinoma patterns. MRP-1 and LRP were overexpressed in all patterns, which may have implications for drug resistance. Further studies are needed to interpret these data regarding to therapy response in advanced staged bronchial-pulmonary carcinomas.

Cellular communication via microparticles: role in transfer of multidrug resistance in cancer

Multidrug resistance (MDR) continues to be a major impediment to the successful treatment of cancer. The two efflux transporters, P-glycoprotein (P-gp) and MRP1 are major contributors to cancer MDR clinically. The upregulation of P-gp leading to MDR was initially understood to occur via pre- and post-transcriptional mechanisms only. However, we demonstrated that microparticles mediate the intercellular exchange and trafficking of bioactive material, including functional P-gp and selected modulatory miRNAs. This exchange of P-gp leads to the dissemination of MDR within a cancer cell population. These findings have significant implications in understanding the cellular basis governing the intercellular acquisition of deleterious traits in cancers, serving to substantially advance our understanding of the molecular basis of the emergence of MDR in cancer clinically.

Transcriptional regulation, stabilization, and subcellular redistribution of multidrug resistance-associated protein 1 (MRP1) by glycogen synthase kinase 3αβ: novel insights on modes of cadmium-induced cell death stimulated by MRP1

Cadmium (Cd) resistance is associated with the suppression of autophagy in H460 lung cancer cells, which is regulated by phospho(p)serine-glycogen synthase kinase (GSK) 3αβ. However, the involvement of multidrug resistance (MDR) in this signaling pathway and its underlying mechanisms remain to be elucidated. In this study, we used Cd-resistant cells (RH460), developed from H460 lung cancer cells, to demonstrate that the induction of MDR-associated protein (MRP1) in response to Cd is enhanced in H460 cells compared to RH460. Treating RH460 cells with Cd induced large cytoplasmic vacuoles, which was inhibited by the autophagy inhibitor 3-methyladenine. MRP1 was detected in the nuclear-rich membrane fractions and redistributed from the perinuclear to the cytoplasmic compartment following exposure to Cd. Cd-induced MRP1, p-Ser/p-Tyr GSK3αβ, and LC3-II were all suppressed by the GSK3 inhibitor SB216763, but increased by lithium. Furthermore, MRP1 was upregulated by the Ser/Thr phosphatase inhibitor okadaic acid and downregulated by the tyrosine phosphatase inhibitor vanadate, suggesting that MRP1 protein was stabilized by p-Ser GSK3αβ. In addition, co-immunoprecipitation and co-localization analyzes revealed a physical interaction between MRP1 and p-Ser GSK3αβ. Genetic knockdown of GSK3β decreased Cd-induced MRP1 mRNA and protein levels, whereas its overexpression upregulated MRP1 protein expression. MRP1 also co-localized with lysosomal membrane protein-2, which may cause lysosomal membrane permeabilization and the subsequent release of cathepsins into the cytosol. In mice chronically injected with Cd, MRP1 localized to the perinuclear region of bronchial and alveolar epithelial cells. Collectively, these data suggest that Cd toxicity is regulated by the transcriptional regulation, stabilization, and subcellular redistribution of MRP1 via the posttranslational modification of GSK3αβ. Therefore, the serine phosphorylation of GSK3αβ plays a critical role in MRP1-induced cell death.