Influence of multidrug resistance and drug transport proteins on chemotherapy drug metabolism

New insights into the interaction between m6A modification and lncRNA in cancer drug resistance

Drug resistance is perhaps the greatest obstacle in improving outcomes for cancer patients, leading to recurrence, progression and metastasis of various cancers. Exploring the underlying mechanism worth further study. N6-methyladenosine (m6A) is the most common RNA modification found in eukaryotes, playing a vital role in RNA translation, transportation, stability, degradation, splicing and processing. Long noncoding RNA (lncRNA) refers to a group of transcripts that are longer than 200 nucleotides (nt) and typically lack the ability to code for proteins. LncRNA has been identified to play a significant role in regulating multiple aspects of tumour development and progression, including proliferation, metastasis, metabolism, and resistance to treatment. In recent years, a growing body of evidence has emerged, highlighting the crucial role of the interplay between m6A modification and lncRNA in determining the sensitivity of cancer cells to chemotherapeutic agents. In this review, we focus on the recent advancements in the interaction between m6A modification and lncRNA in the modulation of cancer drug resistance. Additionally, we aim to explore the underlying mechanisms involved in this process. The objective of this review is to provide valuable insights and suggest potential future directions for the reversal of chemoresistance in cancer.

Molecular panorama of therapy resistance in prostate cancer: a pre-clinical and bioinformatics analysis for clinical translation

Prostate cancer (PCa) is a malignant disorder of prostate gland being asymptomatic in early stages and high metastatic potential in advanced stages. The chemotherapy and surgical resection have provided favourable prognosis of PCa patients, but advanced and aggressive forms of PCa including CRPC and AVPC lack response to therapy properly, and therefore, prognosis of patients is deteriorated. At the advanced stages, PCa cells do not respond to chemotherapy and radiotherapy in a satisfactory level, and therefore, therapy resistance is emerged. Molecular profile analysis of PCa cells reveals the apoptosis suppression, pro-survival autophagy induction, and EMT induction as factors in escalating malignant of cancer cells and development of therapy resistance. The dysregulation in molecular profile of PCa including upregulation of STAT3 and PI3K/Akt, downregulation of STAT3, and aberrant expression of non-coding RNAs are determining factor for response of cancer cells to chemotherapy. Because of prevalence of drug resistance in PCa, combination therapy including co-utilization of anti-cancer drugs and nanotherapeutic approaches has been suggested in PCa therapy. As a result of increase in DNA damage repair, PCa cells induce radioresistance and RelB overexpression prevents irradiation-mediated cell death. Similar to chemotherapy, nanomaterials are promising for promoting radiosensitivity through delivery of cargo, improving accumulation in PCa cells, and targeting survival-related pathways. In respect to emergence of immunotherapy as a new tool in PCa suppression, tumour cells are able to increase PD-L1 expression and inactivate NK cells in mediating immune evasion. The bioinformatics analysis for evaluation of drug resistance-related genes has been performed.

Overcoming drug resistance with specific nano scales to targeted therapy: Focused on metastatic cancers

Metastatic cancer, which accounts for the majority of cancer fatalities, is a difficult illness to treat. Currently used cancer treatments include radiation therapy, chemotherapy, surgery, and targeted treatment (immune, gene, and hormonal). The disadvantages of these treatments include a high risk of tumor recurrence and surgical complications that may result in permanent deformities. On the other hand, most chemotherapy drugs are small molecules, which usually have unfavorable side effects, low absorption, poor selectivity, and multi-drug resistance. Anticancer drugs can be delivered precisely to the cancer spot by encapsulating them to reduce side effects. Stimuli-responsive nanocarriers can be used for drug release at cancer sites and provide target-specific delivery. As previously stated, metastasis is the primary cause of cancer-related mortality. We have evaluated the usage of nano-medications in the treatment of some metastatic tumors.

The Role of Cytokines in Activation of Tumour-promoting Pathways and Emergence of Cancer Drug Resistance

Scientists are constantly researching and launching potential chemotherapeutic agents as an irreplaceable weapon to fight the battle against cancer. Despite remarkable advancement over the past several decades to wipe out cancer through early diagnosis, proper prevention, and timely treatment, cancer is not ready to give up and leave the battleground. It continuously tries to find some other way to give a tough fight for its survival, either by escaping from the effect of chemotherapeutic drugs or utilising its own chemical messengers like cytokines to ensure resistance. Cytokines play a significant role in cancer cell growth and progression, and the present article highlights their substantial contribution to mechanisms of resistance toward therapeutic drugs. Multiple clinical studies have even described the importance of specific cytokines released from cancer cells as well as stromal cells in conferring resistance. Herein, we discuss the different mechanism behind drug resistance and the crosstalk between tumor development and cytokines release and their contribution to showing resistance towards chemotherapeutics. As a part of this review, different approaches to cytokines profile have been identified and employed to successfully target new evolving mechanisms of resistance and their possible treatment options.

The role of Extracellular Vesicles in glycolytic and lipid metabolic reprogramming of cancer cells: Consequences for drug resistance

In order to adapt to a higher proliferative rate and an increased demand for energy sources, cancer cells rewire their metabolic pathways, a process currently recognized as a hallmark of cancer. Even though the metabolism of glucose is perhaps the most discussed metabolic shift in cancer, lipid metabolic alterations have been recently recognized as relevant players in the growth and proliferation of cancer cells. Importantly, some of these metabolic alterations are reported to induce a drug resistant phenotype in cancer cells. The acquisition of drug resistance traits severely hinders cancer treatment, being currently considered one of the major challenges of the oncological field. Evidence suggests that Extracellular Vesicles (EVs), which play a crucial role in intercellular communication, may act as facilitators of tumour progression, survival and drug resistance by modulating several aspects involved in the metabolism of cancer cells. This review aims to gather and discuss relevant data regarding metabolic reprograming in cancer, particularly involving the glycolytic and lipid alterations, focusing on its influence on drug resistance and highlighting the relevance of EVs as intercellular mediators of this process.

Soft Tissue Ewing Sarcoma Cell Drug Resistance Revisited: A Systems Biology Approach

Ewing sarcoma is a rare type of cancer that develops in the bones and soft tissues. Drug therapy represents an extensively used modality for the treatment of sarcomas. However, cancer cells tend to develop resistance to antineoplastic agents, thereby posing a major barrier in treatment effectiveness. Thus, there is a need to uncover the molecular mechanisms underlying chemoresistance in sarcomas and, hence, to enhance the anticancer treatment outcome. In this study, a differential gene expression analysis was conducted on high-throughput transcriptomic data of chemoresistant versus chemoresponsive Ewing sarcoma cells. By applying functional enrichment analysis and protein-protein interactions on the differentially expressed genes and their corresponding products, we uncovered genes with a hub role in drug resistance. Granted that non-coding RNA epigenetic regulators play a pivotal role in chemotherapy by targeting genes associated with drug response, we investigated the non-coding RNA molecules that potentially regulate the expression of the detected chemoresistance genes. Of particular importance, some chemoresistance-relevant genes were associated with the autonomic nervous system, suggesting the involvement of the latter in the drug response. The findings of this study could be taken into consideration in the clinical setting for the accurate assessment of drug response in sarcoma patients and the application of tailored therapeutic strategies.

Modulation of redox homeostasis: A strategy to overcome cancer drug resistance

Cancer treatment is hampered by resistance to conventional therapeutic strategies, including chemotherapy, immunotherapy, and targeted therapy. Redox homeostasis manipulation is one of the most effective innovative treatment techniques for overcoming drug resistance. Reactive oxygen species (ROS), previously considered intracellular byproducts of aerobic metabolism, are now known to regulate multiple signaling pathways as second messengers. Cancer cells cope with elevated amounts of ROS during therapy by upregulating the antioxidant system, enabling tumor therapeutic resistance via a variety of mechanisms. In this review, we aim to shed light on redox modification and signaling pathways that may contribute to therapeutic resistance. We summarized the molecular mechanisms by which redox signaling-regulated drug resistance, including altered drug efflux, action targets and metabolism, enhanced DNA damage repair, maintained stemness, and reshaped tumor microenvironment. A comprehensive understanding of these interrelationships should improve treatment efficacy from a fundamental and clinical research point of view.

Cancer-Associated Fibroblast Heterogeneity, Activation and Function: Implications for Prostate Cancer

The continuous remodeling of the tumor microenvironment (TME) during prostate tumorigenesis is emerging as a critical event that facilitates cancer growth, progression and drug-resistance. Recent advances have identified extensive communication networks that enable tumor-stroma cross-talk, and emphasized the functional importance of diverse, heterogeneous stromal fibroblast populations during malignant growth. Cancer-associated fibroblasts (CAFs) are a vital component of the TME, which mediate key oncogenic events including angiogenesis, immunosuppression, metastatic progression and therapeutic resistance, thus presenting an attractive therapeutic target. Nevertheless, how fibroblast heterogeneity, recruitment, cell-of-origin and differential functions contribute to prostate cancer remains to be fully delineated. Developing our molecular understanding of these processes is fundamental to developing new therapies and biomarkers that can ultimately improve clinical outcomes. In this review, we explore the current challenges surrounding fibroblast identification, discuss new mechanistic insights into fibroblast functions during normal prostate tissue homeostasis and tumorigenesis, and illustrate the diverse nature of fibroblast recruitment and CAF generation. We also highlight the promise of CAF-targeted therapies for the treatment of prostate cancer.

A network pharmacological approach to reveal the multidrug resistance reversal and associated mechanisms of acetogenins against colorectal cancer

Multidrug Resistance (MDR) in tumors is caused by the over-expression of ATP Binding Cassette transporter proteins such as Multidrug Resistance Protein 1 and Breast Cancer Resistance Protein 1. This in silico study focuses on identifying a MDR inhibitor among acetogenins (AGEs) of Annona muricata and also aims at predicting colorectal cancer (CRC) core targets of AGEs through a network pharmacological approach. Twenty-four AGEs were initially screened for their ADME properties. Molecular interaction studies were performed with the two proteins MRP1 and BCRP1. As the structure of MRP1 was not available, an inward-facing conformation of MRP1 was modeled. A Protein-protein interaction network was constructed for the correlating targets of CRC. KEGG pathway and Gene Ontology analysis were performed for the predicted CRC targets. We identified four lead AGEs: Muricatocin B, Annonacinone, Annonacin A and Annomuricin E having a higher binding affinity towards MDR proteins. MD simulation studies performed with the three lead AGEs and the MDR proteins showed that MRP1(DBD): Annomuricin E complex was stable throughout the simulation. Our analysis revealed ABCG2, ERBB2, STAT3, AR, SRC and ABCC1 as CRC targets of the lead molecules. The top 10 signaling pathways and functions of correlative CRC targets were also predicted. We conclude that the identified lead molecules might act as competitive inhibitors for reversing MDR in CRC. Additionally, network pharmacological studies established the correlative CRC targets and their mechanisms of action. Further experimental studies are needed to validate our findings. Communicated by Ramaswamy H. Sarma.

Biological and pharmacological roles of m6A modifications in cancer drug resistance

Cancer drug resistance represents the main obstacle in cancer treatment. Drug-resistant cancers exhibit complex molecular mechanisms to hit back therapy under pharmacological pressure. As a reversible epigenetic modification, N⁶-methyladenosine (m⁶A) RNA modification was regarded to be the most common epigenetic RNA modification. RNA methyltransferases (writers), demethylases (erasers), and m⁶A-binding proteins (readers) are frequently disordered in several tumors, thus regulating the expression of oncoproteins, enhancing tumorigenesis, cancer proliferation, development, and metastasis. The review elucidated the underlying role of m⁶A in therapy resistance. Alteration of the m⁶A modification affected drug efficacy by restructuring multidrug efflux transporters, drug-metabolizing enzymes, and anticancer drug targets. Furthermore, the variation resulted in resistance by regulating DNA damage repair, downstream adaptive response (apoptosis, autophagy, and oncogenic bypass signaling), cell stemness, tumor immune microenvironment, and exosomal non-coding RNA. It is highlighted that several small molecules targeting m⁶A regulators have shown significant potential for overcoming drug resistance in different cancer categories. Further inhibitors and activators of RNA m⁶A-modified proteins are expected to provide novel anticancer drugs, delivering the therapeutic potential for addressing the challenge of resistance in clinical resistance.

Mutual regulation between N6-methyladenosine (m6A) modification and circular RNAs in cancer: impacts on therapeutic resistance

The resistance of tumor cells to therapy severely impairs the efficacy of treatment, leading to recurrence and metastasis of various cancers. Clarifying the underlying mechanisms of therapeutic resistance may provide new strategies for overcoming cancer resistance. N6-methyladenosine (m6A) is the most prevalent RNA modification in eukaryotes, and is involved in the regulation of RNA splicing, translation, transport, degradation, stability and processing, thus affecting several physiological processes and cancer progression. As a novel type of multifunctional non-coding RNAs (ncRNAs), circular RNAs (circRNAs) have been demonstrated to play vital roles in anticancer therapy. Currently, accumulating studies have revealed the mutual regulation of m6A modification and circRNAs, and their interaction can further influence the sensitivity of cancer treatment. In this review, we mainly summarized the recent advances of m6A modification and circRNAs in the modulation of cancer therapeutic resistance, as well as their interplay and potential mechanisms, providing promising insights and future directions in reversal of therapeutic resistance in cancer.

Advances in the Study of CircRNAs in Tumor Drug Resistance

Recent studies have revealed that circRNAs can affect tumor DNA damage and repair, apoptosis, proliferation, and invasion and influence the transport of intratumor substances by acting as miRNA sponges and transcriptional regulators and binding to proteins in a variety of ways. However, research on the role of circRNAs in cancer radiotherapy and chemoresistance is still in its early stages. Chemotherapy is a common approach to oncology treatment, but the development of tumor resistance limits the overall clinical efficacy of chemotherapy for cancer patients. The current study suggests that circRNAs have a facilitative or inhibitory effect on the development of resistance to conventional chemotherapy in a variety of tumors, suggesting that circRNAs may serve as a new direction for the study of antitumor drug resistance. In this review, we will briefly discuss the biological features of circRNAs and summarize the recent progression of the involvement of circRNAs in the development and pathogenesis of cancer chemoresistance.

The Role of m6A Epigenetic Modification in the Treatment of Colorectal Cancer Immune Checkpoint Inhibitors

Tumor immunotherapy, one of the efficient therapies in cancers, has been called to the scientific community's increasing attention lately. Among them, immune checkpoint inhibitors, providing entirely new modalities to treat cancer by leveraging the patient's immune system. They are first-line treatments for varieties of advanced malignancy, such as melanoma, gastrointestinal tumor, esophageal cancer. Although immune checkpoint inhibitors (ICIs) treatment has been successful in different cancers, drug resistance and relapses are common, such as in colorectal cancer. Therefore, it is necessary to improve the efficacy of immune checkpoint therapy for cancer patients who do not respond or lowly response to current treatments. N6-methyladenosine (m6A), as a critical regulator of transcript expression, is the most frequently internal modification of mRNA in the human body. Recently, it has been proposed that m6A epigenetic modification is a potential driver of tumor drug resistance. In this report, we will briefly outline the relevant mechanisms, general treatment status of immune checkpoint inhibitors in colorectal cancer, how m6A epigenetic modifications regulate the response of ICIs in CRC and provide new strategies for overcoming the resistance of ICIs in CRC.

Comparison of Anticancer Drug Toxicities: Paradigm Shift in Adverse Effect Profile

The inception of cancer treatment with chemotherapeutics began in the 1940s with nitrogen mustards that were initially employed as weapons in World War II. Since then, treatment options for different malignancies have evolved over the period of last seventy years. Until the late 1990s, all the chemotherapeutic agents were small molecule chemicals with a highly nonspecific and severe toxicity spectrum. With the landmark approval of rituximab in 1997, a new horizon has opened up for numerous therapeutic antibodies in solid and hematological cancers. Although this transition to large molecules improved the survival and quality of life of cancer patients, this has also coincided with the change in adverse effect patterns. Typically, the anticancer agents are fraught with multifarious adverse effects that negatively impact different organs of cancer patients, which ultimately aggravate their sufferings. In contrast to the small molecules, anticancer antibodies are more targeted toward cancer signaling pathways and exhibit fewer side effects than traditional small molecule chemotherapy treatments. Nevertheless, the interference with the immune system triggers serious inflammation- and infection-related adverse effects. The differences in drug disposition and interaction with human basal pathways contribute to this paradigm shift in adverse effect profile. It is critical that healthcare team members gain a thorough insight of the adverse effect differences between the agents discovered during the last twenty-five years and before. In this review, we summarized the general mechanisms and adverse effects of small and large molecule anticancer drugs that would further our understanding on the toxicity patterns of chemotherapeutic regimens.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

Identification of proteins related with pemetrexed resistance by iTRAQ and PRM-based comparative proteomic analysis and exploration of IGF2BP2 and FOLR1 functions in non-small cell lung cancer cells

Pemetrexed (PEM), a multi-target folate antagonist, has been extensively used for the treatment of non-small cell lung cancer (NSCLC). However, the therapeutic efficacy of PEM is limited by tumor resistance. In this project, iTRAQ and parallel reaction monitoring (PRM)-based LC-MS/MS comparative proteomic analysis was performed to identify protein determinants of PEM resistance in A549/PEM cells versus A549 parental cells. A total of 567 differentially expressed proteins (DEPs) were identified by iTRAQ analysis. The function and classification of DEPs were analyzed through GO and KEGG Pathway databases. Moreover, PRM analysis further validated the expression changes of 14 DEPs identified by iTRAQ analysis. Moreover, insulin-like growth factor (IGF) 2 mRNA-binding protein 2 (IGF2BP2) or folate receptor alpha (FOLR1) knockdown weakened PEM resistance, reduced cell viability and promoted cell apoptosis in A549/PEM cells. IGF2BP2 depletion inhibited cell migration, invasion and epithelial-mesenchymal transition (EMT), while FOLR1 loss had no much effect on cell migration, invasion and EMT in A549/PEM cells. Our study can provide a deep insight into molecular mechanisms of PEM resistance in NSCLC and contribute to the development of more effective therapeutic schedules. SIGNIFICANCE: Our study can provide deeper insight into molecular mechanisms of PEM resistance in NSCLC and contribute to the development of more effective therapeutic schedules.

Effect of vitamin D on malignant behavior of non-small cell lung cancer cells

OBJECTIVE

To investigate the effects of vitamin D on the malignant behavior of A549 and NCI-H1975 tumor cells (proliferation, apoptosis, invasion, metastasis and drug resistance-related proteins) and the activation of the PI3K/AKT/mTOR signaling pathway, in order to evaluate the effect of vitamin D on the therapeutic action of cisplatin.

METHOD

In vitro cell experiments, CCK-8, flow cytometry, transwell, scratches, MTT and Western blot were used to reveal the effect of vitamin D on non-small cell lung cancer (NSCLC), and the expression of PI3K/AKT/mTOR signaling pathway was also detected. In vivo animal experiments, the nude mice were divided into four groups: control group, vitamin D treatment group, cisplatin treatment group and vitamin D + cisplatin combined treatment group. After tumor formation in vitro, tumor volume changes were calculated and tumor growth curves were drawn, collected tumor tissues for pathological sections. Western blot was used to detect the expression changes of drug-resistance related proteins in tumor tissues. Meanwhile, protein expression changes of PI3K/AKT/mTOR signaling pathway in tumor tissues were detected.

RESULT

In vitro experiments confirm Vitamin D can inhibit the proliferation, invasion and metastasis of non-small cell lung cancer cells A549 and NCI-H1975, promoting cell apoptosis, up-regulate the sensitivity of chemotherapy drugs. These effects of vitamin D may be correlated with the PI3K/AKT/mTOR signaling pathway. In vivo animal experiments, the changes in tumor volume, tumor inflammatory infiltration range, expression of drug-resistant related proteins and signaling pathway related proteins in mice were as follows: The vitamin D and cisplatin combined treatment group was significantly smaller than the control group.

CONCLUSION

Vitamin D can inhibit the proliferation, invasion and metastasis of non-small cell lung cancer (NSCLC) cells A549 and NCI-H1975 and promote apoptosis, up-regulate the sensitivity of chemotherapy drugs. The effect of vitamin D on NSCLC cells A549 and NCI-H1975 was correlated with the PI3K/AKT/mTOR signaling pathway. Vitamin D also promotes the therapeutic effect of CDDP.

Cancer stem cells and nanomedicine: new opportunities to combat multidrug resistance?

'Multidrug resistance' (MDR) is a difficult challenge for cancer treatment. The combined role of cytochrome P450 enzymes (CYPs) and active efflux transporters (AETs) in cancer cells appears relevant in inducing MDR. Chemotherapeutic drugs can be substrates of both CYPs and AETs and CYP inducers or inhibitors can produce the same effects on AETs. In addition, a small subpopulation of cancer stem-like cells (CSCs) appears to survive conventional chemotherapy, leading to recurrent disease. Natural products appear efficacious against CSCs; their combinational treatments with standard chemotherapy are promising for cancer eradication, in particular when supported by nanotechnologies.

Challenges and Opportunities in Cancer Drug Resistance

There has been huge progress in the discovery of targeted cancer therapies in recent years. However, even for the most successful and impactful cancer drugs which have been approved, both innate and acquired mechanisms of resistance are commonplace. These emerging mechanisms of resistance have been studied intensively, which has enabled drug discovery scientists to learn how it may be possible to overcome such resistance in subsequent generations of treatments. In some cases, novel drug candidates have been able to supersede previously approved agents; in other cases they have been used sequentially or in combinations with existing treatments. This review summarizes the current field in terms of the challenges and opportunities that cancer resistance presents to drug discovery scientists, with a focus on small molecule therapeutics. As part of this review, common themes and approaches have been identified which have been utilized to successfully target emerging mechanisms of resistance. This includes the increase in target potency and selectivity, alternative chemical scaffolds, change of mechanism of action (covalents, PROTACs), increases in blood-brain barrier permeability (BBBP), and the targeting of allosteric pockets. Finally, wider approaches are covered such as monoclonal antibodies (mAbs), bispecific antibodies, antibody drug conjugates (ADCs), and combination therapies.

The Role of Specific ATP-Binding Cassette Transporters in the Acquired Resistance to Pyrrolobenzodiazepine Dimer-Containing Antibody-Drug Conjugates

Antibody-drug conjugates (ADC) containing pyrrolobenzodiazepine (PBD) dimers are being evaluated clinically in both hematologic and solid tumors. These include ADCT-301 (camidanlumab tesirine) and ADCT-402 (loncastuximab tesirine) in pivotal phase II trials that contain the payload tesirine, which releases the PBD dimer warhead SG3199. An important consideration in future clinical development is acquired resistance. The aim was to generate and characterize PBD acquired resistant cell lines in both hematologic and solid tumor settings. Human Karpas-299 (ALCL) and NCI-N87 (gastric cancer) cells were incubated with increasing IC₅₀ doses of ADC (targeting CD25 and HER2, respectively) or SG3199 in a pulsed manner until stable acquired resistance was established. The level of resistance achieved was approximately 3,000-fold for ADCT-301 and 3-fold for SG3199 in Karpas-299, and 8-fold for ADCT-502 and 4-fold for SG3199 in NCI-N87. Cross-resistance between ADC and SG3199, and with an alternative PBD-containing ADC or PBD dimer was observed. The acquired resistant lines produced fewer DNA interstrand cross-links, indicating an upstream mechanism of resistance. Loss of antibody binding or internalization was not observed. A human drug transporter PCR Array revealed several genes upregulated in all the resistant cell lines, including ABCG2 and ABCC2, but not ABCB1(MDR1). These findings were confirmed by RT-PCR and Western blot, and inhibitors and siRNA knockdown of ABCG2 and ABCC2 recovered drug sensitivity. These data show that acquired resistance to PBD-ADCs and SG3199 can involve specific ATP-binding cassette drug transporters. This has clinical implications as potential biomarkers of resistance and for the rational design of drug combinations.

The Exploitation of Liposomes in the Inhibition of Autophagy to Defeat Drug Resistance

Autophagy is a mechanism involved in many human diseases and in cancers can have a cytotoxic/cytostatic or protective action, being in the latter case involved in multidrug resistance. Understanding which of these roles autophagy has in cancer is thus fundamental for therapeutical decisions because it permits to optimize the therapeutical approach by activating or inhibiting autophagy according to the progression of the disease. However, a serious drawback of cancer treatment is often the scarce availability of drugs and autophagy modulators at the sites of interest. In the recent years, several nanocarriers have been developed and investigated to improve the solubility, bioavailability, controlled release of therapeutics and increase their cytotoxic effect on cancer cell. Here we have reviewed only liposomes as carriers of chemotherapeutics and autophagy inhibitors because they have low toxicity and immunogenicity and they are biodegradable and versatile. In this review after the analysis of the dual role of autophagy, of the main autophagic pathways, and of the role of autophagy in multidrug resistance, we will focus on the most effective liposomal formulations, thus highlighting the great potential of these targeting systems to defeat cancer diseases.

Functions and mechanisms of circular RNAs in cancer radiotherapy and chemotherapy resistance

Circular RNAs (circRNAs), one type of non-coding RNA, were initially misinterpreted as nonfunctional products of pre-mRNA mis-splicing. Currently, circRNAs have been proven to manipulate the functions of diverse molecules, including non-coding RNAs, mRNAs, DNAs and proteins, to regulate cell activities in physiology and pathology. Accumulating evidence indicates that circRNAs play critical roles in tumor genesis, development, and sensitivity to radiation and chemotherapy. Radiotherapy and chemotherapy are two primary types of intervention for most cancers, but their therapeutic efficacies are usually retarded by intrinsic and acquired resistance. Thus, it is urgent to develop new strategies to improve therapeutic responses. To achieve this, clarification of the underlying mechanisms affecting therapeutic responses in cancer is needed. This review summarizes recent progress and mechanisms of circRNAs in cancer resistance to radiation and chemotherapy, and it discusses the limitations of available knowledge and potential future directions.

New genetic variations discovered in KRAS wild-type cetuximab resistant chinese colorectal cancer patients

To perform a comprehensive genomic analysis of colorectal cancer (CRC) tumor to detect genetic variants and identify novel resistant mutations associated with cetuximab-resistance in CRC patients. A retrospective study was performed using whole exome sequencing (WES) to identify common genetic factors from 22 cetuximab-sensitive and 10 cetuximab-resistant patients. In all 10 cetuximab-resistant patients, we discovered there are 37 significantly mutated genes (SMGs). CYP4A11 was the most frequently mutated gene in cetuximab-resistant patients. BCAS1 and GOLGA6L1 were found to be among the second group of frequently mutated genes with a frequency of 60%. After cosine similarity analysis, three mutational signatures (signature a, b, and c) were found in all CRC tumors, similar to signature 1, 5, and 6 in COSMIC, respectively. Gene ontology analysis was performed on SMGs and found 12 enriched GO terms. Four genes are enriched in six specific Kyoto Encyclopedia of Genes and Genomes pathway groups, including the metabolism of xenobiotics by cytochrome P450, steroid hormone biosynthesis, retinol metabolism, and drug metabolism. Our data supports a network composed of SMGs and cellular signaling pathways that have been positively linked to the mechanisms of cetuximab resistance. These involve DNA damage repair, angiogenesis, invasion, drug metabolism, and the CRC tumor microenvironment. There is a SMG, OR9G1 correlated with survival rates of KRAS wild-type colon adenocarcinoma patients. These findings support further investigation using WES in a prospective clinical study of cetuximab resistance CRC, to further identify, confirm, and extend the clinical significance of these and other potentially important new candidate predictive biomarkers of cetuximab response.

Cisplatin resistance in gastric cancer cells is involved with GPR30-mediated epithelial-mesenchymal transition

Cisplatin is the major chemotherapeutic drug in gastric cancer, particularly in treating advanced gastric cancer. Tumour cells often develop resistance to chemotherapeutic drugs, which seriously affects the efficacy of chemotherapy. GPR30 is a novel oestrogen receptor that is involved in the invasion, metastasis and drug resistance of many tumours. Targeting GPR30 has been shown to increase the drug sensitivity of breast cancer cells. However, few studies have investigated the role of GPR30 in gastric cancer. Epithelial‐mesenchymal transition (EMT) has been shown to be associated with the development of chemotherapeutic drug resistance. In this study, we demonstrated that GPR30 is involved in cisplatin resistance by promoting EMT in gastric cancer. GPR30 knockdown resulted in increased sensitivity of different gastric cancer (GC) cells to cisplatin and alterations in the epithelial/mesenchymal markers. Furthermore, G15 significantly enhanced the cisplatin sensitivity of GC cells while G1 inhibited this phenomenon. In addition, EMT occurred when AGS and BGC‐823 were treated with cisplatin. Down‐regulation of GPR30 with G15 inhibited this transformation, while G1 promoted it. Taken together, these results revealed the role of GPR30 in the formation of cisplatin resistance, suggesting that targeting GPR30 signalling may be a potential strategy for improving the efficacy of chemotherapy in gastric cancer.

Characterisation and proteomic profiling of continuously exposed Cu-resistant variants of the Caco-2 cell line

Studies in hepatic systems identify multiple factors involved in the generation of copper resistance. As the intestine is the route of exposure to dietary copper, we wanted to understand how intestinal cells overcome the toxic effects of high copper and what mechanisms of resistance develop. Using the intestinal cell line Caco-2, resistance was developed by serial subculture in 50 μM copper in inorganic (CuSO₄) or organic (Cu proteinate) forms. Caco-2 variants exhibited resistance to copper and retained the non-monotonic dose response while displaying stable phenotypes following repeated subculture in the absence of copper. Phenotypic changes on exposure to copper in parental Caco-2 cells included significantly increased total protein yield, ROS, SOD, metallothionein expression, GSH and total glutathione. These phenotypic changes were not replicated in resistant variants on a per cell basis. Quantitative label-free LC-MS/MS proteomic analysis identified 1113 differentially expressed proteins (DEPs) between parental Caco-2 and resistant cells. With some exceptions, most of the DEPs were overexpressed to a low level around 2-fold suggesting resistance was supported by multiple small changes in protein expression. These variants may be a useful tool in studying the toxicity of stress responses in further Cu-related studies.

Mebendazole as a Candidate for Drug Repurposing in Oncology: An Extensive Review of Current Literature

Anticancer treatment efficacy is limited by the development of refractory tumor cells characterized by increased expression and activity of mechanisms promoting survival, proliferation, and metastatic spread. The present review summarizes the current literature regarding the use of the anthelmintic mebendazole (MBZ) as a repurposed drug in oncology with a focus on cells resistant to approved therapies, including so called “cancer stem cells”. Mebendazole meets many of the characteristics desirable for a repurposed drug: good and proven toxicity profile, pharmacokinetics allowing to reach therapeutic concentrations at disease site, ease of administration and low price. Several in vitro studies suggest that MBZ inhibits a wide range of factors involved in tumor progression such as tubulin polymerization, angiogenesis, pro-survival pathways, matrix metalloproteinases, and multi-drug resistance protein transporters. Mebendazole not only exhibits direct cytotoxic activity, but also synergizes with ionizing radiations and different chemotherapeutic agents and stimulates antitumoral immune response. In vivo, MBZ treatment as a single agent or in combination with chemotherapy led to the reduction or complete arrest of tumor growth, marked decrease of metastatic spread, and improvement of survival. Further investigations are warranted to confirm the clinical anti-neoplastic activity of MBZ and its safety in combination with other drugs in a clinical setting.

Emerging strategies in cancer therapy combining chemotherapy with immunotherapy

Cancer immunotherapy holds great potential to battle cancer by exerting a durable immunity effect. However, this process might be limited by various constraints existing in the tumor microenvironment (TME), such as the lack of available neoantigen, insufficient T cells from the naive repertoire, or immunosuppressive networks in which immunogenic tissue is protected from immune attacks. Certain chemotherapeutic drugs could elicit immune-potentiating effects by either inducing immunogenicity or relieving tumor-induced immunosuppression. Some also leave tumors directly susceptible to cytotoxic T cell attacks. Mounting evidence accumulated from preclinical and clinical studies suggests that these two treatment modalities might be mutually reinforcing as an effective "chemo-immunotherapy" strategy. Herein, we reviewed the latest advances in cancer immunotherapy and related mechanisms involved in chemotherapeutic-mediated immune activation. The emerging combination strategies and synergistic effects in response to chemo-immunotherapy are highlighted. We also discuss the challenges and critical considerations in its future development.

Rising horizon in circumventing multidrug resistance in chemotherapy with nanotechnology

Multidrug resistance (MDR) is one of the key barriers in chemotherapy, leading to the generation of insensitive cancer cells towards administered therapy. Genetic and epigenetic alterations of the cells are the consequences of MDR, resulted in drug resistivity, which reflects in impaired delivery of cytotoxic agents to the cancer site. Nanotechnology-based nanocarriers have shown immense shreds of evidence in overcoming these problems, where these promising tools handle desired dosage load of hydrophobic chemotherapeutics to facilitate designing of safe, controlled and effective delivery to specifically at tumor microenvironment. Therefore, encapsulating drugs within the nano-architecture have shown to enhance solubility, bioavailability, drug targeting, where co-administered P-gp inhibitors have additionally combat against developed MDR. Moreover, recent advancement in the stimuli-sensitive delivery of nanocarriers facilitates a tumor-targeted release of the chemotherapeutics to reduce the associated toxicities of chemotherapeutic agents in normal cells. The present article is focused on MDR development strategies in the cancer cell and different nanocarrier-based approaches in circumventing this hurdle to establish an effective therapy against deadliest cancer disease.

SKA1 induces de novo MTX-resistance in osteosarcoma through inhibiting FPGS transcription

De novo methotrexate (MTX)-resistance, whose underlying mechanism remains largely unknown, usually leads to very poor prognosis in patients with osteosarcoma (OS). In this study, we established the de novo MTX-resistant OS cell line SF-86 and identified the candidate gene spindle and kinetochore associated complex subunit 1 (SKA1) as potentially related to de novo MTX-resistance. Analysis of a cohort of 95 OS patients demonstrated that SKA1 overexpression significantly correlated with de novo MTX-resistance and poor 5-year survival. Mechanistically, SKA1 overexpression lead to a downregulation of folylpoly-γ-glutamate synthetase (FPGS), a key enzyme that converts MTX into its active form, MTX-PG. We further demonstrated that SKA1 interacts with DNA-directed RNA polymerase II subunit RPB3. ChIP analysis revealed that RPB3 binds the promoter region of the FPGS gene and triggers FPGS transcription upon MTX treatment in SW1353, a MTX-sensitive OS cell line lacking endogenous SKA1 expression. On the contrary, this process is blocked in SF-86 cells due to the formation of an inhibitory SKA1-RPB3 complex. Furthermore, downregulation of SKA1 levels restores MTX sensitivity in SF-86. Collectively, our study has established the de novo MTX-resistant cell line SF-86 and identified SKA1 as a novel regulator of FPGS, playing a key role in the development of de novo MTX-resistance in OS.

Recent Progress in Macromolecule-Anchored Hybrid Gold Nanomaterials for Biomedical Applications

Gold nanoparticles (AuNPs), with elegant thermal, optical, or chemical properties due to quantum size effects, may serve as unique species for therapeutic or diagnostic applications. It is worth mentioning that their small size also results in high surface activity, leading to significantly impaired stability, which greatly hinders their biomedical utilizations. To overcome this problem, various types of macromolecular materials are utilized to anchor AuNPs so as to achieve advanced synergistic effect by dispersing, protecting, and stabilizing the AuNPs in polymeric-Au hybrid self-assemblies. In this review, the most recent development of polymer-AuNP hybrid systems, including AuNPs@polymeric nanoparticles, AuNPs@polymeric micelle, AuNPs@polymeric film, and AuNPs@polymeric hydrogel are discussed with respect to their different synthetic strategies. These sophisticated materials with diverse functions, oriented toward biomedical applications, are further summarized into several active domains in the areas of drug delivery, gene delivery, photothermal therapy, antibacterials, bioimaging, etc. Finally, the possible approaches for future design of multifunctional polymer-AuNP hybrids by combining hybrid chemistry with biological interface science are proposed.

Organoselenium Compounds as Novel Adjuvants of Chemotherapy Drugs-A Promising Approach to Fight Cancer Drug Resistance

Malignant diseases present a serious public health burden and their treatment with traditional chemotherapy cannot be considered an all-round solution, due to toxic side effects. Selenium compounds (Se-compounds) have received substantial attention in medicinal chemistry, especially in experimental chemotherapy, both as cytotoxic agents and adjuvants in chemotherapy. A checkerboard microplate method was applied to study the drug interactions of Se-compounds and clinically relevant chemotherapeutic drugs against the multidrug-resistant (MDR) subtype of mouse t-lymphoma cells overexpressing the ABCB1 transporter. Se-compounds showed synergistic interactions with chemotherapeutic agents targeting the topoisomerase enzymes or the microtubule apparatus. The ketone-containing selenoesters showed synergism at lower concentrations (1.25 µM). Most of the tested compounds interacted antagonistically with alkylating agents and verapamil. A thiophene-containing Se-compound showed synergism with all tested drugs, except cisplatin. While the exact mechanism of drug interactions is yet unknown, the potency of the selenocompounds as efflux pump inhibitors or the potentiation of their efficacy as reactive oxygen species modulators may play a role in their complementary activity against the tested MDR lymphoma cell line.

A step-wise synthetic approach is necessary to access γ-conjugates of folate: folate-conjugated prodigiosenes

Despite the vast literature that describes reacting folic acid with a pharmacophore, this route is ineffective in providing the correct regioisomer of the resulting conjugate. We herein present a step-wise route to the preparation of nine folate conjugates of the tripyrrolic prodigiosene skeleton. The strict requirement for step-wise construction of the folate core is demonstrated, so as to achieve conjugation at only the desired γ-carboxylic acid and thus maintain the α-carboxylic site for folate receptor (FRα) recognition. Linkages via ethylenediamine, polyethylene glycol and glutathione are demonstrated.

Despite the vast literature that describes reacting folic acid with a pharmacophore, this route is ineffective in providing the correct regioisomer of the resulting conjugate.

Dose adjustment in orphan disease populations: the quest to fulfill the requirements of physiologically based pharmacokinetics

INTRODUCTION

While the media is engaged and fascinated by the idea of 'Precision Medicine', the nuances related to 'Precision Dosing' seem to be largely ignored. Assuming the 'right drug' is selected, clinicians still need to decide on the 'right dose' for individuals. Ideally, optimal dosing should be studied in clinical trials; however, many drugs on the market lack evidence-based dosing recommendations, and small groups of patients (orphan disease populations) are dependent on local guidance and clinician experience to determine drug dosage adjustments. Areas Covered: This report explores the current understanding of dosing adjustment in special populations and examines the requirements for developing 'in silico' models for pediatric, elderly and pregnant patients. The report also highlights current use of modeling to provide evidence-based recommendations for drug labeling in the absence of complete clinical trials in orphan disease populations. Expert Opinion: Physiologically based pharmacokinetics (PBPK) is an attractive prospect for determining the best drug dosage adjustments in special populations. However, it is not sufficient for individualized, or even stratified dosing, unless the systems (drug-independent) data required to build robust PBPK models are obtained. Such models are not a substitute for clinical trials, but they are an alternative to undocumented and inconsistent guesswork.

Systematic identification of non-coding pharmacogenomic landscape in cancer

Emerging evidence has shown long non-coding RNAs (lncRNAs) play important roles in cancer drug response. Here we report a lncRNA pharmacogenomic landscape by integrating multi-dimensional genomic data of 1005 cancer cell lines and drug response data of 265 anti-cancer compounds. Using Elastic Net (EN) regression, our analysis identifies 27,341 lncRNA-drug predictive pairs. We validate the robustness of the lncRNA EN-models using two independent cancer pharmacogenomic datasets. By applying lncRNA EN-models of 49 FDA approved drugs to the 5605 tumor samples from 21 cancer types, we show that cancer cell line based lncRNA EN-models can predict therapeutic outcome in cancer patients. Further lncRNA-pathway co-expression analysis suggests lncRNAs may regulate drug response through drug-metabolism or drug-target pathways. Finally, we experimentally validate that EPIC1, the top predictive lncRNA for the Bromodomain and Extra-Terminal motif (BET) inhibitors, strongly promotes iBET762 and JQ-1 resistance through activating MYC transcriptional activity.

Effects of quercetin on the pharmacokinetics of losartan and its metabolite EXP3174 in rats

1. This study investigates the influence of quercetin on the pharmacokinetics of losartan and its metabolite EXP3174 in rats. 2. The pharmacokinetic profiles of losartan and EXP3174 of orally administered losartan (10 mg/kg) with or without pretreatment with quercetin (20 mg/kg/day for 7 days) were investigated. Additionally, Caco-2 cell transwell model and rat liver microsome incubation experiments were also conducted to investigate its potential mechanism. 3. The results showed that when the rats were pretreated with quercetin, the C_max (2.16 ± 0.40 vs. 1.33 ± 0.21 mg/L) and the AUC_(0-t) (13.89 ± 1.22 vs. 7.34 ± 0.75 mg·h/L) of losartan increased significantly (p < .05), and while the C_max (0.76 ± 0.09 vs. 1.14 ± 0.18 mg/L) of EXP3174 decreased significantly compared to the control (p < .05). The t_1/2 of losartan was prolonged from 3.27 ± 0.45 h to 4.74 ± 0.51 h (p < .05). The results also indicated that quercetin could increase losartan absorption rate by inhibiting the activity of P-gp and decrease its metabolic stability by inhibiting the activity of CYP450 enzyme. 4. These results indicated that the herb-drug interaction between quercetin and losartan might occur when they are co-administered in rats, quercetin could increase the systemic exposure of losartan and decrease the plasma concentration of EXP3174, possibly by inhibiting the activity of P-gp or CYP450 enzyme.

Molecular dissection of the valproic acid effects on glioma cells

Many glioblastoma patients suffer from seizures why they are treated with antiepileptic agents. Valproic acid (VPA) is a histone deacetylase inhibitor that apart from its anticonvulsive effects in some retrospective studies has been suggested to lead to a superior outcome of glioblastoma patients. However, the exact molecular effects of VPA treatment on glioblastoma cells have not yet been deciphered. We treated glioblastoma cells with VPA, recorded the functional effects of this treatment and performed a global and unbiased next generation sequencing study on the chromatin (ChIP) and RNA level. 1) VPA treatment clearly sensitized glioma cells to temozolomide: A protruding VPA-induced molecular feature in this context was the transcriptional upregulation/reexpression of numerous solute carrier (SLC) transporters that was also reflected by euchromatinization on the histone level and a reexpression of SLC transporters in human biopsy samples after VPA treatment. DNA repair genes were adversely reduced. 2) VPA treatment, however, also reduced cell proliferation in temozolomide-naive cells: On the molecular level in this context we observed a transcriptional upregulation/reexpression and euchromatinization of several glioblastoma relevant tumor suppressor genes and a reduction of stemness markers, while transcriptional subtype classification (mesenchymal/proneural) remained unaltered. Taken together, these findings argue for both temozolomide-dependent and -independent effects of VPA. VPA might increase the uptake of temozolomide and simultaneously lead to a less malignant glioblastoma phenotype. From a mere molecular perspective these findings might indicate a surplus value of VPA in glioblastoma therapy and could therefore contribute an additional ratio for clinical decision making.

Different growth and metastatic phenotypes associated with a cell-intrinsic change of Met in metastatic melanoma

A dynamic phenotypic change contributes to the metastatic progression and drug resistance in malignant melanoma. Nevertheless, mechanisms for a phenotypic change have remained to be addressed. Here, we show that Met receptor expression changes in a cell-autonomous manner and can distinguish phenotypical differences in growth, as well as in metastatic and drug-resistant characteristics. In metastatic melanoma, the cells are composed of Met-low and Met-high populations. Met-low populations have stem-like gene expression profiles, are resistant to chemotherapeutic agents, and have shown abundant angiogenesis and rapid tumor growth in subcutaneous inoculation. Met-high populations have a differentiated phenotype, are relatively resistant to B-RAF inhibitor, and are highly metastatic to the lungs. Met plays a definitive role in lung metastasis because the lung metastasis of Met-high cells requires Met, and treatment of mice with the Met-containing exosomes from Met-high cells facilitates lung metastasis by Met-low cells. Clonal cell fate analysis showed the hierarchical phenotypical changes from Met-low to Met-high populations. Met-low cells either showed self-renewal or changed into Met-high cells, whereas Met-high cells remained Met-high. Clonal transition from Met-low to Met-high cells accompanied changes in the gene expression profile, in tumor growth, and in metastasis that were similar to those in Met-high cells. These findings indicate that malignant melanoma has the ability to undergo phenotypic change by a cell-intrinsic/autonomous mechanism that can be characterized by Met expression.

Mycoplasma-associated multidrug resistance of hepatocarcinoma cells requires the interaction of P37 and Annexin A2

Mycoplasma infection has been reported to be associated with cancer migration, invasion, epithelial-mesenchymal transition as well as the resistance to nucleoside analogues chemotherapeutic drugs. In this study, we found that the sensitivity of hepatocarcinoma cells to Cisplatin, Gemcitabine and Mitoxantrone was increased by mycoplasma elimination. Similar to the effect of anti-mycoplasma agent, interrupting the interaction between Mycoplasma hyorhinis membrane protein P37 and Annexin A2 of host cells using the N-terminal of ANXA2 polypeptide enhanced the sensitivity of HCC97L cells to Gemcitabine and Mitoxantrone. Meanwhile, we did not observe any changes in expression or distribution of multidrug resistance associated transporters, ATP-Binding Cassette protein B1, C1 and G2, on the removal of mycoplasma. These results suggest that mycoplasma induces a resistance to multiple drugs in hepatocarcinoma cells which required the interaction of P37 and Annexin A2. The pathway downstream this interaction needs to be explored.

Recent advances in protein engineering and biotechnological applications of glutathione transferases

Glutathione transferases (GSTs, EC 2.5.1.18) are a widespread family of enzymes that play a central role in the detoxification, metabolism, and transport or sequestration of endogenous or xenobiotic compounds. During the last two decades, delineation of the important structural and catalytic features of GSTs has laid the groundwork for engineering GSTs, involving both rational and random approaches, aiming to create new variants with new or altered properties. These approaches have expanded the usefulness of native GSTs, not only for understanding the fundamentals of molecular detoxification mechanisms, but also for the development medical, analytical, environmental, and agricultural applications. This review article attempts to summarize successful examples and current developments on GST engineering, highlighting in parallel the recent knowledge gained on their phylogenetic relationships, structural/catalytic features, and biotechnological applications.

Lysosome-associated protein transmembrane4β is involved in multidrug resistance processes of colorectal cancer

Colorectal cancer (CRC) is one of the most common reasons for cancer-associated mortality worldwide. The present study aimed to investigate the drug resistance mechanism of the oxaliplatin (OXA)-resistant HT-29 cell line (HT-29/L-OHP) and examine the expression of lysosome-associated protein transmembrane 4β (LAPTM4β), a drug resistance-associated gene. In the present study, a drug concentration gradient method was used to establish the drug-resistant HT-29/L-OHP cell line. Cell apoptosis was analyzed by flow cytometry. LAPTM4β mRNA expression was examined by reverse transcription-quantitative polymerase chain reaction analysis and LAPTM4β-35 expression was examined by western blot analysis. Cell morphology of the HT-29/L-OHP drug-resistant cell line was examined. The results indicated that the intercellular space among HT-29 cells was small, with aggregative growth while the intercellular space among HT-29/L-OHP cells was large, with scattered growth. The apoptotic rate in HT-29/L-OHP cells (11.7%) was significantly lower compared with that in HT-29 cells (17.7%) (P<0.05). LAPTM4β mRNA expression in HT-29/L-OHP cells was significantly increased compared with that in HT-29 cells (P<0.05). The relative expression of LAPTM4β-35 protein in HT-29/L-OHP cells was significantly higher compared with that inHT-29 cells (P<0.05). In conclusion, LAPTM4β may be involved in the multidrug resistance processes of CRC. Therefore, LAPTM4β may serve as a novel biomarker for drug resistance of CRC.

Shikonin enhances Adriamycin antitumor effects by inhibiting efflux pumps in A549 cells

Shikonin (SHK) is a natural naphthoquinone pigment isolated from Lithospermum erythrorhizon, that has been reported to suppress the growth of a number of cancer cell types. Adriamycin (AD) is typically used as an effective anticancer agent; however, it has the propensity to induce drug resistance. The aim of the present study was to investigate the effects of SHK alone and in combination with AD on lung adenocarcinoma cells and the underlying molecular mechanisms of their effects. Colony formation, MTT and propidium iodide staining assays demonstrated that the co-treatment of A549 cells with SHK and AD significantly decreased cell viability and potently induced apoptosis. The mitochondrial membrane potential was assessed using 5,5', 6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazolylcarbocyanine iodide staining and fluorescence microscopy. Cells co-treated with SHK and AD exhibited marked mitochondrial membrane damage. In addition, co-treatment with SHK and AD significantly reduced ATP levels in A549 cells compared with the control. Western blot analysis revealed that SHK enhanced the antitumor effects of AD by inhibiting the expression of ATP-binding cassette transporters. These results suggest that the inhibition of glycolysis could be an effective approach for lung cancer treatment. Therefore, SHK has the potential to be used as an anticancer agent in the treatment of lung adenocarcinoma, and thus warrants further investigation and development.

Human cancer-associated fibroblasts enhance glutathione levels and antagonize drug-induced prostate cancer cell death

Drug resistance is a major problem in cancer therapy. A growing body of evidence demonstrates that the tumor microenvironment, including cancer-associated fibroblasts (CAFs), can modulate drug sensitivity in tumor cells. We examined the effect of primary human CAFs on p53 induction and cell viability in prostate cancer cells on treatment with chemotherapeutic drugs. Co-culture with prostate CAFs or CAF-conditioned medium attenuated DNA damage and the p53 response to chemotherapeutic drugs and enhanced prostate cancer cell survival. CAF-conditioned medium inhibited the accumulation of doxorubicin, but not taxol, in prostate cancer cells in a manner that was associated with increased cancer cell glutathione levels. A low molecular weight fraction (<3 kDa) of CAF-conditioned medium had the same effect. CAF-conditioned medium also inhibited induction of reactive oxygen species (ROS) in both doxorubicin- and taxol-treated cancer cells. Our findings suggest that CAFs can enhance drug resistance in cancer cells by inhibiting drug accumulation and counteracting drug-induced oxidative stress. This protective mechanism may represent a novel therapeutic target in cancer.

The TLR3 Agonist Inhibit Drug Efflux and Sequentially Consolidates Low-Dose Cisplatin-Based Chemoimmunotherapy while Reducing Side Effects

The traditional maximum dose density chemotherapy renders the tumor patients not only the tumor remission but the chemotherapy resistance and more adverse side effects. According to the widely positive expression of Toll-like receptor (TLR)-3 in oral squamous cell carcinoma (OSCC) patients (n = 166), we here provided an alternative strategy involved the orderly treatment of TLR3 agonist polyinosine-polycytidylic acid (PIC) and low-dose cisplatin. The optimal dose of cisplatin, the novel role of PIC and the side effects of the combined chemotherapy were determined in vitro and in distinct human tumor models in vivo The results in vitro indicated that preculture with PIC downregulated drug transporters (e.g., P-gp and MRP-1) and increased the cytoplasmic residence of cisplatin, and dramatically strengthened the low-dose cisplatin-induced cell death in TLR3- and caspase-3-dependent manner. Meanwhile, the spleen immunocytes were activated but the immunosuppressive cancer-associated fibroblasts (CAF) were dampened. These findings were confirmed in human tumor models in vivo Pretreatment with PIC promoted the low-dose cisplatin residence for tumor regression with decreased myeloid-suppressive cells (MDSC), tumor-associated macrophages (TAM) and CAFs, and alleviated adverse side effects in the OSCC model, which was further enhanced by the Cetuximab safely. This strategy also repressed the progression of melanoma and lymphoma. Moreover, TLR3 negatively manipulated the inflammation-related long noncoding RNA lnc-IL7R, which was upregulated during this chemotherapy. Knockdown of lnc-IL7R improved the chemotherapy sensitivity. Overall, this study provided preclinically new instructions for the PIC/cisplatin utilization to target tumor microenvironment and strengthen the low-dose cisplatin-based chemotherapy with reduced side effects. Mol Cancer Ther; 16(6); 1068-79. ©2017 AACR.

Breast tumor stroma: A driving force in the development of resistance to therapies

Breast cancer is the most common cancer and the second leading cause of cancer-related death in women worldwide. In spite of huge advancements in early detection and ever-increasing knowledge of breast cancer biology, approximately 30% of patients with early-stage breast cancer experience disease recurrence. Most patients are chemosensitive and cancer free immediately after the treatment. About 50% to 70% of breast cancer patients, however, will relapse within 1 year. Such a relapse is usually concomitant with adenocarcinoma cells acquiring a chemoresistant phenotype. Both de novo and acquired chemoresistance are poorly understood and present a major burden in the treatment of breast cancer. Although, previously, chemoresistance was largely linked to genetic alterations within the cancer cells, recent investigations are indicating that chemoresistance can also be associated with the tumor microenvironment. Nowadays, it is widely believed that tumor microenvironment is a key player in tumor progression and response to treatment. In this study, we will review the interactions of breast tumor cells with their microenvironment, present the latest research on the resistance mediated by the stromal component in breast cancer, and discuss the potential therapeutic strategies that can be exploited to treat breast cancers by targeting tumor microenvironment.

Effects of berberine on the pharmacokinetics of losartan and its metabolite EXP3174 in rats and its mechanism

CONTEXT

Losartan and berberine (BBR) are often simultaneously used for the treatment of senile diabetic nephropathy in clinics. However, the potential herb-drug interaction between losartan and BBR is unknown.

OBJECTIVE

This study investigates the influence of BBR on the pharmacokinetics of losartan and EXP3174, and investigates the effects of BBR on the metabolic stability of losartan.

MATERIALS AND METHODS

The pharmacokinetic profiles losartan and EXP3174 of orally administered losartan (10 mg/kg) with and without pretreatment with BBR (20 mg/kg) within 24 h were determined in Sprague-Dawley rats. The inhibitory effects of BBR on the metabolic stability of losartan were investigated using rat liver microsomes.

RESULTS

The C_max (1.26 ± 0.37 versus 1.96 ± 0.45 mg/L) and the AUC_(0-t) (8.25 ± 0.89 versus 12.70 ± 1.42 mg h/L) of losartan were significantly (p < 0.05) increased by BBR compared to the control, while the C_max (0.97 ± 0.15 versus 0.77 ± 0.06 mg/L) of EXP3174 was significantly decreased compared to the control (p < 0.05). The T_max of losartan was prolonged from 0.41 ± 0.12 to 0.52 ± 0.18 h, but the difference was not significant. However, the T_max of EXP3174 was decreased significantly (p < 0.05) from 8.14 ± 0.36 to 3.33 ± 0.28 h. The metabolic stability of losartan was increased from 37.4 to 59.6 min.

DISCUSSION AND CONCLUSION

We infer that BBR might increase the plasma concentration of losartan and decrease the concentration of EXP3174 through inhibiting the activity of CYP3A4 or CYP2C9.

SLCO1B1*5 polymorphism (rs4149056) is associated with chemotherapy-induced amenorrhea in premenopausal women with breast cancer: a prospective cohort study

Background

Because inheritance is recognized as playing a role in age at menarche and natural menopause, the development of chemotherapy-induced amenorrhea (CIA) might depend on inherited genetic factors; however, studies that explore such a correlation are few and have received scant attention. Given the importance of this topic we conducted a comprehensive genotype study in young women (≤45 years) with early-stage breast cancer.

Methods

Our approach tested the effect of variant polymorphisms in drug metabolism enzymes (DMEs) using a predesigned pharmacogenomics panel (TaqMan® OpenArray®, Life Technologies GmbH, Darmstadt, Germany) in premenopausal women (n = 50). Patients received contemporary chemotherapy; in all cases a cyclophosphamide-based regimen with a dose of at least 500 mg/m² for six cycles. CIA was considered to be present in women with no resumption of menstrual bleeding within 12 months after completion of chemotherapy or goserelin.

Results

Twenty-six patients (52 %) showed CIA during follow-up whereas 24 women (48 %) remained premenopausal. Of all the DMEs studied, only the SLCO1B1*5 (rs4149056) genotype was associated with the development of CIA (P = 0.017). Of the 26 patients who were homozygous for the T/T allele SLCO1B1*5, 18 (69.2 %) developed CIA compared with 8 (30.8 %) of the 22 patients who were heterozygous (C/T allele). The association of heterozygous SLCO1B1*5 allele (OR 0.038; 95%CI: 0.05–0.92) with a lower risk of developing CIA remained significant in a binary logistic regression analysis that include age, SLCO1B1*5 allele variants, and goserelin therapy.

Conclusions

Patient age and SLCO1B1*5 allele variants predict the likelihood of young women with breast cancer developing CIA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2373-3) contains supplementary material, which is available to authorized users.

The role of glucuronidation in drug resistance

The final therapeutic effect of a drug candidate, which is directed to a specific molecular target strongly depends on its absorption, distribution, metabolism and excretion (ADME). The disruption of at least one element of ADME may result in serious drug resistance. In this work we described the role of one element of this resistance: phase II metabolism with UDP-glucuronosyltransferases (UGTs). UGT function is the transformation of their substrates into more polar metabolites, which are better substrates for the ABC transporters, MDR1, MRP and BCRP, than the native drug. UGT-mediated drug resistance can be associated with (i) inherent overexpression of the enzyme, named intrinsic drug resistance or (ii) induced expression of the enzyme, named acquired drug resistance observed when enzyme expression is induced by the drug or other factors, as food-derived compounds. Very often this induction occurs via ligand binding receptors including AhR (aryl hydrocarbon receptor) PXR (pregnane X receptor), or other transcription factors. The effect of UGT dependent resistance is strengthened by coordinate action and also a coordinate regulation of the expression of UGTs and ABC transporters. This coupling of UGT and multidrug resistance proteins has been intensively studied, particularly in the case of antitumor treatment, when this resistance is "improved" by differences in UGT expression between tumor and healthy tissue. Multidrug resistance coordinated with glucuronidation has also been described here for drugs used in the management of epilepsy, psychiatric diseases, HIV infections, hypertension and hypercholesterolemia. Proposals to reverse UGT-mediated drug resistance should consider the endogenous functions of UGT.