Multidrug resistance transporters P-gp and BCRP limit the efficacy of ATR inhibitor ceralasertib in cancer cells.

The therapeutic effect of chemotherapy and targeted therapy are known to be limited by drug resistance. Substantial evidence has shown that ATP-binding cassette (ABC) transporters P-gp and BCRP are significant contributors to multidrug resistance (MDR) in cancer cells. In this study, we demonstrated that a clinical-staged ATR inhibitor ceralasertib is susceptible to P-gp and BCRP-mediated MDR. The drug resistant cancer cells were less sensitive to ceralasertib compared to the parental cells. Moreover, ceralasertib resistance can be reversed by inhibiting the drug efflux activity of P-gp and BCRP. Interestingly, ceralasertib was able to downregulate the level of P-gp but not BCRP, suggesting a potential regulation between ATR signaling and P-gp expression. Furthermore, computational docking analysis predicted high affinities between ceralasertib and the drug-binding sites of P-gp and BCRP. In summary, overexpression of P-gp and BCRP are sufficient to confer cancer cells resistance to ceralasertib, underscoring their role as biomarkers for therapeutic efficacy.

N/O Co-doped hierarchical nanoporous biochar derived from waste polypropylene nonwoven for high-performance supercapacitors.

How to efficiently treat municipal solid waste (MSW) has become one of the critical solutions in response to the call for "carbon neutrality". Here, the waste polypropylene nonwoven fabric of waste diapers was converted into hierarchical nanoporous biochar (HPBC) through pre-carbonization and activation processes as an ideal precursor for supercapacitors (SCs) with excellent performance. The prepared HPBC-750-4 with an ultrahigh specific surface area (3838.04 m2 g-1) and abundant heteroatomic oxygen (13.25%) and nitrogen (1.16%) codoped porous biochar structure. Given its structural advantages, HPBC-750-4 achieved a specific capacitance of 340.9 F g-1 at a current density of 1 A g-1 in a three-electrode system. Its capacitance retention rate was above 99.2% after 10 000 cycles at a current density of 10 A g-1, which indicated an excellent rate capability and long-term cycling stability. Furthermore, the HPBC-750-4//HPBC-750-4 symmetric SC exhibited a superb energy density of 10.02 W h kg-1 with a power density of 96.15 W kg-1 in a 6 M KOH electrolyte. This work not only demonstrates the enormous potential of waste polypropylene nonwoven fabric in the SC industry but also provides an economically feasible means of managing MSW.

Heterogeneous treatment effects of coronary artery bypass grafting in ischemic cardiomyopathy: A machine learning causal forest analysis.

OBJECTIVES: We aim to evaluate the heterogeneous treatment effects of coronary artery bypass grafting in patients with ischemic cardiomyopathy and to identify a group of patients to have greater benefits from coronary artery bypass grafting compared with medical therapy alone. METHODS: Machine learning causal forest modeling was performed to identify the heterogeneous treatment effects of coronary artery bypass grafting in patients with ischemic cardiomyopathy from the Surgical Treatment for Ischemic Heart Failure trial. The risks of death from any cause and death from cardiovascular causes between coronary artery bypass grafting and medical therapy alone were assessed in the identified subgroups. RESULTS: Among 1212 patients enrolled in the Surgical Treatment for Ischemic Heart Failure trial, left ventricular end-systolic volume index, serum creatinine, and age were identified by the machine learning algorithm to distinguish patients with heterogeneous treatment effects. Among patients with left ventricular end-systolic volume index greater than 84 mL/m2 and age 60.27 years or less, coronary artery bypass grafting was associated with a significantly lower risk of death from any cause (adjusted hazard ratio, 0.61; 95% CI, 0.45-0.84) and death from cardiovascular causes (adjusted hazard ratio, 0.63; 95% CI, 0.45-0.89). By contrast, the survival benefits of coronary artery bypass grafting no longer exist in patients with left ventricular end-systolic volume index 84 mL/m2 or less and serum creatinine 1.04 mg/dL or less, or patients with left ventricular end-systolic volume index greater than 84 mL/m2 and age more than 60.27 years. CONCLUSIONS: The current post hoc analysis of the Surgical Treatment for Ischemic Heart Failure trial identified heterogeneous treatment effects of coronary artery bypass grafting in patients with ischemic cardiomyopathy. Younger patients with severe left ventricular enlargement were more likely to derive greater survival benefits from coronary artery bypass grafting.

Epigenome-wide DNA methylation analysis of myasthenia gravis.

Myasthenia gravis (MG) is a common neuromuscular junction disorder and autoimmune disease mediated by several antibodies. Several studies have shown that genetic factors play an important role in MG pathogenesis. To gain insight into the epigenetic factors affecting MG, we report here genome-scale DNA methylation profiles of MG. DNA was extracted from eight MG patients and four healthy controls for genome-wide DNA methylation analysis using the Illumina HumanMethylation 850K BeadChip. Verification of pyrosequencing was conducted based on differential methylation positions. Subsequently, C2C12 and HT22 cell lines (derived from mouse) were treated with demethylation drugs. Transcribed mRNA of the screened differential genes was detected using quantitative real-time PCR. The control and MG group were compared, and two key probe positions were selected. The corresponding genes were CAMK1D and CREB5 (P < 0.05). Similarly, the myasthenic crisis (MC) and non-MC group were compared and four key probe positions were selected. The corresponding genes were SAV1, STK3, YAP1, and WWTR1 (P < 0.05). Subsequently, pyrosequencing was performed for verification, revealing that hypomethylation of CAMK1D was significantly different between the MG and control group (P < 0.001). Moreover, transcription of CREB5, PKD, YAP1, and STK3 genes in the C2C12 cells was downregulated (P < 0.05) after drug treatment, but only YAP1 mRNA was downregulated in HT22 cells (P < 0.05). This is the first study to investigate genome-scale DNA methylation profiles of MG using 850 K BeadChip. The identified molecular markers of methylation may aid in the prevention, diagnosis, treatment, and prognosis of MG.

Case report: A longitudinal study of an unusual rapidly progressive dementia case.

It is daunting to determine the etiology of rapidly progressive dementia (RPD), which includes metabolic, neoplastic, infectious, autoimmune, neurodegenerative and other conditions. Herein, we illustrate an unusual case of a patient primarily exhibiting RPD, overlapping sleep dysfunction, psychosis and abnormal movement, which was finally defined as anti-IgLON5 disease, a novel and rare autoimmune encephalopathy. Furthermore, we longitudinally described his cognitive and psychological performance in detail, and determined that early initiation of immunotherapy in this patient did not result in a good outcome. These data highlight anti-IgLON5 disease as a possible differential diagnosis in patients with RPD.

Association of lung-intestinal microecology and lung cancer therapy.

In recent years, the incidence of lung cancer is increasing. Lung cancer has become one of the most malignant tumors with the highest incidence in the world, which seriously affects people's health. The most important cause of death of lung cancer is metastasis. Therefore, it is crucial to understand the mechanism of lung cancer progression and metastasis. This review article discusses the physiological functions, pathological states and disorders of the lung and intestine based on the concepts of traditional Chinese medicine (TCM), and analyzes the etiology and mechanisms of lung cancer formation from the perspective of TCM. From the theory of "the exterior and interior of the lung and gastrointestinal tract", the theory of "the lung-intestinal axis" and the progression and metastasis of lung cancer, we proposed e "lung-gut co-treatment" therapy for lung cancer. This study provides ideas for studying the mechanism of lung cancer and the comprehensive alternative treatment for lung cancer patients.

Protective Effects of Resveratrol Against Adenomyosis in a Mouse Model.

Adenomyosis is a uterine condition in which endometrial glands and stroma are commonly pathologically observed in the myometrium. In this study, we sought to determine the effect of resveratrol on the progression of adenomyosis. Adenomyosis was induced in mice given tamoxifen neonatally. All mice were subjected to body weight measurement and hotplate testing every four weeks beginning four weeks after birth. All mice with adenomyosis were randomly separated into 3 groups at 16 weeks: untreated, low-dose resveratrol (25 mg/kg), and high-dose resveratrol (50 mg/kg). After 3 weeks of treatment, final hotplate test and body weight measurement were performed, and the uterine horn blood samples were collected. Adenomyosis in mice caused body weight loss and uterine weight gain, reduced hotplate latency, and progression of endometrial fibrosis. The underlying biological process could be coupled with the overexpression of many cells' proliferation and immune-regulation-related genes. Resveratrol treatment could slow the progression of adenomyosis by enhancing hotplate latency, lowering endometrial fibrosis, and restoring cell proliferation- and immune-regulation-associated gene expression levels in endometrium and plasma. However, resveratrol treatment also reduced the body weight and uterine weight. In conclusion, Resveratrol might be a potential compound for treating patients with adenomyosis.

CAR T cells: engineered immune cells to treat brain cancers and beyond.

Malignant brain tumors rank among the most challenging type of malignancies to manage. The current treatment protocol commonly entails surgery followed by radiotherapy and/or chemotherapy, however, the median patient survival rate is poor. Recent developments in immunotherapy for a variety of tumor types spark optimism that immunological strategies may help patients with brain cancer. Chimeric antigen receptor (CAR) T cells exploit the tumor-targeting specificity of antibodies or receptor ligands to direct the cytolytic capacity of T cells. Several molecules have been discovered as potential targets for immunotherapy-based targeting, including but not limited to EGFRvIII, IL13Rα2, and HER2. The outstanding clinical responses to CAR T cell-based treatments in patients with hematological malignancies have generated interest in using this approach to treat solid tumors. Research results to date support the astounding clinical response rates of CD19-targeted CAR T cells, early clinical experiences in brain tumors demonstrating safety and evidence for disease-modifying activity, and the promise for further advances to ultimately assist patients clinically. However, several variable factors seem to slow down the progress rate regarding treating brain cancers utilizing CAR T cells. The current study offers a thorough analysis of CAR T cells' promise in treating brain cancer, including design and delivery considerations, current strides in clinical and preclinical research, issues encountered, and potential solutions.

Nivolumab and relatlimab for the treatment of melanoma.

Melanoma is a highly lethal type of skin cancer. Although an early diagnosis, in combination with surgery for nonmetastatic melanomas, significantly increases the probability of survival, there are no efficacious treatments for metastatic melanoma. Nivolumab and relatlimab are monoclonal antibodies that selectively interact with and block the proteins programmed cell death protein 1 (PD-1) and lymphocyte activation protein 3 (LAG-3), respectively, and thus, their activation by their cognate ligands. The combination of these immunotherapy drugs was approved in 2022 by the United States Food and Drug Administration (FDA) for the treatment of melanoma. Data from clinical trials indicated that, compared to nivolumab monotherapy, nivolumab and relatlimab produced more than a 2-fold median increase in progression-free survival (PFS) and a higher response rate in melanoma patients. This is an important finding as the response of patients to immunotherapies is limited due to dose-limiting toxicities and secondary drug resistance. This review article will discuss the pathogenesis of melanoma and the pharmacology of nivolumab and relatlimab. In addition, we will provide i) a summary of the anticancer drugs that inhibit LAG-3 and PD-1 in cancer patients and ii) our perspective about the use of nivolumab in combination with relatlimab to treat melanoma.

METTL1 promotes neuroblastoma development through m7G tRNA modification and selective oncogenic gene translation.

BACKGROUND: Neuroblastoma (NBL) is the most common extra-cranial solid tumour in childhood, with prognosis ranging from spontaneous remission to high risk for rapid and fatal progression. Despite existing therapy approaches, the 5-year event-free survival (EFS) for patients with advanced NBL remains below 30%, emphasizing urgent necessary for novel therapeutic strategies. Studies have shown that epigenetic disorders play an essential role in the pathogenesis of NBL. However, the function and mechanism of N7-methylguanosine (m7G) methyltransferase in NBL remains unknown. METHODS: The expression levels of m7G tRNA methyltransferase Methyltransferase-like 1 (METTL1) were analyzed by querying the Gene Expression Omnibus (GEO) database and further confirmed by immunohistochemistry (IHC) assay. Kaplan-Meier, univariate and multivariate cox hazard analysis were performed to reveal the prognostic role of METTL1. Cell function assays were performed to evaluate how METTL1 works in proliferation, apoptosis and migration in cell lines and xenograft mouse models. The role of METTL1 on mRNA translation activity of NBL cells was measured using puromycin intake assay and polysome profiling assay. The m7G modified tRNAs were identified by tRNA reduction and cleavage sequencing (TRAC-seq). Ribosome nascent-chain complex-bound mRNA sequencing (RNC-seq) was utilized to identify the variation of gene translation efficiency (TE). Analyzed the codon frequency decoded by m7G tRNA to clarify the translation regulation and mechanism of m7G modification in NBL. RESULTS: This study found that METTL1 were significantly up-regulated in advanced NBL, which acted as an independent risk factor and predicted poor prognosis. Further in NBL cell lines and BALB/c-nu female mice, we found METTL1 played a crucial role in promoting NBL progression. Furthermore, m7G profiling and translation analysis revealed downregulation of METTL1 would inhibit puromycin intake efficiency of NBL cells, indicating that METTL1 did count crucially in regulation of NBL cell translation. With all tRNAs with m7G modification identified in NBL cells, knockdown of METTL1 would significantly reduce the levels of both m7G modification and m7G tRNAs expressions. Result of RNC-seq shew there were 339 overlapped genes with impaired translation in NBL cells upon METTL1 knockdown. Further analysis revealed these genes contained higher frequency of codons decoded by m7G-modified tRNAs and were enriched in oncogenic pathways. CONCLUSION: This study revealed the critical role and mechanism of METTL1-mediated tRNA m7G modification in regulating NBL progression, providing new insights for developing therapeutic approaches for NBL patients.

Objectification and ambiguity of body image in women with Polycystic Ovary Syndrome: A mixed-method study.

BACKGROUND: The manifestations of Polycystic Ovary Syndrome (PCOS), including acne, hirsutism, obesity, uncertain fertility, etc., can make women anxious, worried, or even depressed with their appearance and body. However, little relevant research has been conducted in the Chinese context. This mixed-method study aimed to understand how women with PCOS in China perceive their bodies and to examine the association between body image and depression. METHODS: First, 101 PCOS patients participated in a survey using the Body Surveillance subscale of the Objectified Body Consciousness Scale, the Short-form Mishel Uncertainty in Illness Scale, the Appearance Anxiety Scale, and the Beck Depression Inventory-II, which measured participants' self-objectification, illness ambiguity, appearance anxiety, and depression, respectively. Second, fifteen women joined face-to-face semi-structured in-depth interviews, investigating their illness ambiguity, objectified experience, and behaviors to pursue beauty. RESULTS: Results indicated a high level of self-objectification, illness ambiguity, appearance anxiety, and depression among women with PCOS in China and supported the significant associations among the outcomes. Qualitative findings presented a body image of the precarious body, indiscernible identity, and distraught mind. LIMITATIONS: A convenient sampling method was used. The generalization of the study results needs further validation. Future longitudinal studies are necessary to clarify the causal relationships among outcomes. CONCLUSIONS: This study presented women's body image with PCOS and found the negative impact of body image on their depression levels. This study was of both theoretical and practical significance. Appropriate mind-body therapies were suggested for them.

Microbiota in health and diseases.

The role of microbiota in health and diseases is being highlighted by numerous studies since its discovery. Depending on the localized regions, microbiota can be classified into gut, oral, respiratory, and skin microbiota. The microbial communities are in symbiosis with the host, contributing to homeostasis and regulating immune function. However, microbiota dysbiosis can lead to dysregulation of bodily functions and diseases including cardiovascular diseases (CVDs), cancers, respiratory diseases, etc. In this review, we discuss the current knowledge of how microbiota links to host health or pathogenesis. We first summarize the research of microbiota in healthy conditions, including the gut-brain axis, colonization resistance and immune modulation. Then, we highlight the pathogenesis of microbiota dysbiosis in disease development and progression, primarily associated with dysregulation of community composition, modulation of host immune response, and induction of chronic inflammation. Finally, we introduce the clinical approaches that utilize microbiota for disease treatment, such as microbiota modulation and fecal microbial transplantation.

Chinese Medicine Formula Siwu-Yin Inhibits Esophageal Precancerous Lesions by Improving Intestinal Flora and Macrophage Polarization.

Siwu-Yin (SWY), a traditional Chinese medicinal formula, can replenish blood and nourish Yin. It was recorded in ancient Chinese medicine books in treating esophageal dysphagia, which has similar symptoms and prognosis with esophageal precancerous lesions and esophageal cancer. However, its effect has not been established in vivo. This study explores the antiesophageal cancer effect of SWY on rats with esophageal precancerous lesions. By performing 16S rRNA gene sequencing and metabolomics, it was suggested that SWY may improve the composition of intestinal flora of rats by regulating the synthesis and secretion of bile acids. In addition, flow cytometry results showed that SWY treatment modified tumor microenvironment by improving macrophage polarization and therefore inhibiting the occurrence of esophageal precancerous lesions.

Intrauterine administration of G-CSF for promoting endometrial growth after hysteroscopic adhesiolysis: a randomized controlled trial.

STUDY QUESTION: Does intrauterine infusion of granulocyte colony-stimulating factor (G-CSF) prevent adhesion reformation and promote endometrial growth after hysteroscopic adhesiolysis? SUMMARY ANSWER: Intrauterine perfusion of G-CSF can increase endometrial thickness but does not prevent the recurrence of intrauterine adhesions (IUAs) in patients with Asherman syndrome (AS) after surgery. WHAT IS KNOWN ALREADY: Intrauterine infusion of G-CSF has been used in attempts to treat patients with recurrent miscarriage and an idiopathic thin endometrium for either fresh or frozen-thawed embryo transfer cycles but without uniform efficacy. There have been no reports on the effect of G-CSF on the recurrence of IUAs, endometrial regrowth or pregnancy results in specific populations with AS. STUDY DESIGN, SIZE, DURATION: This two-center prospective double-blind randomized controlled trial ran between April 2016 and August 2021. In it, 245 patients with moderate to severe AS were randomized to G-CSF and control groups at a 1:1 ratio; 229 women were included in the adhesion recurrence analysis; and 164 patients were analyzed for pregnancy outcomes. PARTICIPANTS/MATERIALS, SETTING, METHODS: All eligible patients received the first hysteroscopic adhesion separation and balloon placement procedure. Patients who met our inclusion and exclusion criteria were randomized after surgery. These patients returned for balloon removal and underwent intrauterine perfusion with 300 µg (1.8 ml) G-CSF or 1.8 ml normal saline according to randomization at 7 days after surgery. A second-look hysteroscopy was carried out 1-2 months later. The primary outcome was the rate of formation of new adhesions at the second hysteroscopy. The secondary outcomes included endometrial thickness in the periovulatory period after surgery, as well as the clinical pregnancy and live birth rates. MAIN RESULTS AND THE ROLE OF CHANCE: Age, menstrual cycle characteristics, pregnancy history and IUA score before surgery were similar between groups. There were no statistically significant differences in the adhesion reformation rate or median adhesion score reduction. However, G-CSF perfusion significantly improved endometrial thickness (7.91 ± 2.12 mm vs 7.22 ± 2.04 mm; P = 0.019, 95% CI for difference: -1.26 to -0.12), as well as cumulative pregnancy and live birth rate over time (P = 0.017 and P = 0.042). Furthermore, multivariate logistic regression analysis showed that postoperative endometrial thickness was an independent prognostic factor for pregnancy and live birth rates. LIMITATIONS, REASONS FOR CAUTION: These results cannot be extended to older patients or those without AS, as our subjects had moderate or severe AS and were aged <40 years. The low number of patients included in the fertility analysis could lead to biased results. WIDER IMPLICATIONS OF THE FINDINGS: Intrauterine perfusion of G-CSF could be an effective adjuvant therapy for patients with AS to increase endometrial thickness. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by grants from the National Key Research and Development Program of China (2018YFC1004800), the National Natural Science Foundation of China (82001624 and 81871209), the Natural Science Foundation of Zhejiang Province (LQ20H040004) and the provincial and ministerial construction project of Zhejiang Province (2017 WKJ-ZJ-1721). The authors declare that they have no conflicts of interest regarding this work. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT02855632). TRIAL REGISTRATION DATE: 4 March 2016. DATE OF FIRST PATIENT'S ENROLMENT: 13 April 2016.

Neuronal reprogramming in treating spinal cord injury.

Spinal cord injury represents a devastating central nervous system injury that could impair the mobility and sensory function of afflicted patients. The hallmarks of spinal cord injury include neuroinflammation, axonal degeneration, neuronal loss, and reactive gliosis. Furthermore, the formation of a glial scar at the injury site elicits an inhibitory environment for potential neuroregeneration. Besides axonal regeneration, a significant challenge in treating spinal cord injury is to replenish the neurons lost during the pathological process. However, despite decades of research efforts, current strategies including stem cell transplantation have not resulted in a successful clinical therapy. Furthermore, stem cell transplantation faces serious hurdles such as immunorejection of the transplanted cells and ethical issues. In vivo neuronal reprogramming is a recently developed technology and leading a major breakthrough in regenerative medicine. This innovative technology converts endogenous glial cells into functional neurons for injury repair in the central nervous system. The feasibility of in vivo neuronal reprogramming has been demonstrated successfully in models of different neurological disorders including spinal cord injury by numerous laboratories. Several reprogramming factors, mainly the pro-neural transcription factors, have been utilized to reprogram endogenous glial cells into functional neurons with distinct phenotypes. So far, the literature on in vivo neuronal reprogramming in the model of spinal cord injury is still small. In this review, we summarize a limited number of such reports and discuss several questions that we think are important for applying in vivo neuronal reprogramming in the research field of spinal cord injury as well as other central nervous system disorders.

Overexpression of ABCC1 Confers Drug Resistance to Betulin.

Betulin is a lupane-type pentacyclic triterpene, which is isolated from birch bark. It has a broad spectrum of biological and pharmacological properties, such as anti-inflammatory, anti-tumor, anti-viral, and anti-bacterial activity. Herein, we explored the factors that may result in betulin resistance, especially with respect to its interaction with ATP-binding cassette subfamily C member 1 (ABCC1). ABCC1 is an important member of the ATP-binding cassette (ABC) transporter family, which is central to mediating multidrug resistance (MDR) in naturally derived anticancer agents. An MTT-based cell viability assay showed that ABCC1 overexpression has the ability to desensitize both cancer cell line and gene-transfected cell line to betulin and that this betulin-induced resistance can be antagonized by a known ABCC1 inhibitor MK571 at 25 µM. Additionally, betulin upregulates the ABCC1 protein expression level in both concentration-dependent and time-dependent manners, also blocks the transport function mediated by ABCC1. Subsequently, a high affinity score of betulin was achieved in a computational docking analysis, demonstrating a strong interaction of betulin with ABCC1.

LINC00649 promotes bladder cancer malignant progression by regulating the miR­15a­5p/HMGA1 axis.

The aim of the present study was to explore the effects of LINC00649 on the proliferation, migration and invasion of bladder cancer (BC) and identify possible mechanisms. Through TCGA database analysis of LINC00649 expression in bladder cancer and the association of LINC00649 with the BC patient prognosis, RT­qPCR was employed for detecting LINC00649 expression in 60 clinical tissue specimens and cell lines of bladder cancer. The lentivirus stable transfection or small interfering RNA was used to increase or decrease the LINC00649 expression level in T24 and UM­UC­3 cells. CCK8 and clone formation assay were utilized to observe the effects of LINC00649 on the proliferation and colony formation of BC cells. Transwell experiment was performed to detect the effects of LINC00649 on the migration and invasion of bladder cancer. Bioinformatics database was used to identify the possible downstream targets of LINC00649 while RT­qPCR, western blot analysis and dual luciferase reporter gene experiments were carried out to verify the possible molecular mechanism. The TCGA database analysis revealed a significantly high expression of LINC00649 in bladder cancer and an association of LINC00649 expression with overall survival rate of BC patients. As shown by RT­qPCR detection, LINC00649 expression was notably upregulated in BC tissues and BC cell lines. In addition, statistical analyses unveiled that highly expressed LINC00649 was clearly associated with poor overall survival of bladder cancer. Based on the in vitro cell experiment, upregulated LINC00649 considerately enhanced the proliferation, migration and invasion of BC cells, as opposed to those in T24 and UM­UC­3 cells by suppressing LINC00649. Mechanically, LINC00649 may promote the malignant progression of bladder cancer by regulating miR­15a­5p to promote the HMGA1 expression axis. Overall, LINC00649 upregulates HMGA1 expression by binding to miR­15a­5p to enhance the proliferation, migration and invasion of BC cells. Thus, LINC00649 is a potential biomarker and therapeutic target for bladder cancer.

Natural Product as Substrates of ABC Transporters: A Review.

BACKGROUND: To date, many compounds extracted from natural products have anti-tumor activity, such as citronellol, ellagitannin-containing pomegranate extract, etc. Evidence from clinical context shows that multidrug resistance is an obstacle that impedes the effectiveness of natural products, such as chemotherapeutic agents, paclitaxel and vincristine. Overexpression of ATP- Binding Cassette (ABC) transporters is the leading cause of MDR. Therefore, it is crucial to investigate whether these natural products are substrates of MDR-associated ABC transporters, which may benefit the development of their clinical usage. OBJECTIVE: This review summarizes the latest insight on natural products possessing substrate profile and analyzes some possible directions for future drug discovery. CONCLUSION: The anti-tumor effects of natural products are constantly being explored, but the drug resistance issues cannot be ignored, which limits their prospects as anti-tumor drugs to a certain extent. At the same time, some natural products are taken as a daily diet, and their possible role in increasing the drug resistance of the substrate should arouse the attention of clinical cancer patients.

NVP-CGM097, an HDM2 Inhibitor, Antagonizes ATP-Binding Cassette Subfamily B Member 1-Mediated Drug Resistance.

Multidrug resistance (MDR) is a major challenge in the treatment of tumors. It refers to cancer cells become resistant to not only the therapeutic drug, but also cross-resistant to multiple drugs with distinct structures and mechanisms of action when they are exposed to a drug for a period of time. An essential mechanism of MDR is the aberrant expression and function of ATP-binding cassette (ABC) transporters. Therefore, blocking the function of ABC transporters has the therapeutic potential in reversing MDR. The hdm2 oncogene product, HDM2 (also known as MDM2), is an important negative regulator of the p53 tumor suppressor. NVP-CGM097 is an HDM2 inhibitor that can inhibit the proliferation of tumor cells and is currently under clinical trials. In this study, we evaluate whether NVP-CGM097 could reverse ABCB1-mediated MDR. The results of reversal experiment showed that NVP-CGM097 remarkably reversed ABCB1-mediated MDR but not ABCG2-mediated MDR. The results of Western blot and immunofluorescence suggested that the level of expression and subcellular localization of ABCB1 protein were not significantly altered by NVP-CGM097. Mechanism studies indicated that NVP-CGM097 could reverse ABCB1-mediated MDR by directly blocking the ABCB1-mediated drug efflux and raising the accumulation of chemotherapeutic drugs in cancer cells. ATPase analysis showed that low concentration NVP-CGM097 activates ABCB1 ATPase activity while high concentration NVP-CGM097 inhibited ABCB1-associated ATPase. Docking study indicated that NVP-CGM097 tended to bind to the inhibitory site, which led to slight but critical conformational changes in the transporter and reduced the ATPase activity. Overall, our study demonstrates that NVP-CGM097 can be used in conjunction with chemotherapeutic drugs to counteract MDR and improve the antitumor responses.

Erdafitinib Antagonizes ABCB1-Mediated Multidrug Resistance in Cancer Cells.

ABCB1 overexpression is known to contribute to multidrug resistance (MDR) in cancers. Therefore, it is critical to find effective drugs to target ABCB1 and overcome MDR. Erdafitinib is a tyrosine kinase inhibitor (TKI) of fibroblast growth factor receptor (FGFR) that is approved by the FDA to treat urothelial carcinoma. Previous studies have demonstrated that some TKIs exhibit MDR reversal effect. In this work, we examined whether erdafitinib could reverse MDR mediated by ABCB1. The results of reversal experiments showed that erdafitinib remarkably reversed ABCB1-mediated MDR without affecting ABCG2-mediated MDR. The results of immunofluorescence and Western blot analysis demonstrated that erdafitinib did not affect the expression of ABCB1 or its cellular localization. Further study revealed that erdafitinib inhibited ABCB1 efflux function leading to increasing intracellular drug accumulation, thereby reversing MDR. Furthermore, ATPase assay indicated that erdafitinib activated the ABCB1 ATPase activity. Docking study suggested that erdafitinib interacted with ABCB1 on the drug-binding sites. In summary, this study demonstrated that erdafitinib can reverse MDR mediated by ABCB1, suggesting that combination of erdafitinib and ABCB1-substrate conventional chemotherapeutic drugs could potentially be used to overcome MDR mediated by ABCB1.