Circadian rhythm response and its effect on photosynthetic characteristics of the Lhcb family genes in tea plant.

BACKGROUND: The circadian clock, also known as the circadian rhythm, is responsible for predicting daily and seasonal changes in the environment, and adjusting various physiological and developmental processes to the appropriate times during plant growth and development. The circadian clock controls the expression of the Lhcb gene, which encodes the chlorophyll a/b binding protein. However, the roles of the Lhcb gene in tea plant remain unclear. RESULTS: In this study, a total of 16 CsLhcb genes were identified based on the tea plant genome, which were distributed on 8 chromosomes of the tea plant. The promoter regions of CsLhcb genes have a variety of cis-acting elements including hormonal, abiotic stress responses and light response elements. The CsLhcb family genes are involved in the light response process in tea plant. The photosynthetic parameter of tea leaves showed rhythmic changes during the two photoperiod periods (48 h). Stomata are basically open during the day and closed at night. Real-time quantitative PCR results showed that most of the CsLhcb family genes were highly expressed during the day, but were less expressed at night. CONCLUSIONS: Results indicated that CsLhcb genes were involved in the circadian clock process of tea plant, it also provided potential references for further understanding of the function of CsLhcb gene family in tea plant.

Double pyramid stacked CoO nano-crystals induced by graphene at low temperatures as highly efficient Fenton-like catalysts.

Transition metal oxides are widely used as Fenton-like catalysts in the treatment of organic pollutants, but their synthesis usually requires a high temperature. Herein, an all-solid-state synthesis method controlled by graphene was used to prepare a double pyramid stacked CoO nano-crystal at a low temperature. The preparation temperature decreased by 200 °C (over 30% reduction) due to the introduction of graphene, largely reducing the reaction energy barrier. Interestingly, the corresponding degradation rate constants (kobs) of this graphene-supported pyramid CoO nano-crystals for organic molecules after their adsorption were over 2.5 and 35 times higher than that before adsorption and that of free CoO, respectively. This high catalytic efficiency is attributed to the adsorption of pollutants at the surface by supporting graphene layers, while free radicals activated by CoO can directly and rapidly contact and degrade them. These findings provide a new strategy to prepare low carbon-consuming transition metal oxides for highly efficient Fenton-like catalysts.

Differential Response of MYB Transcription Factor Gene Transcripts to Circadian Rhythm in Tea Plants (Camellia sinensis).

The circadian clock refers to the formation of a certain rule in the long-term evolution of an organism, which is an invisible 'clock' in the body of an organism. As one of the largest TF families in higher plants, the MYB transcription factor is involved in plant growth and development. MYB is also inextricably correlated with the circadian rhythm. In this study, the transcriptome data of the tea plant 'Baiyeyihao' were measured at a photoperiod interval of 4 h (24 h). A total of 25,306 unigenes were obtained, including 14,615 unigenes that were annotated across 20 functional categories within the GO classification. Additionally, 10,443 single-gene clusters were annotated to 11 sublevels of metabolic pathways using KEGG. Based on the results of gene annotation and differential gene transcript analysis, 22 genes encoding MYB transcription factors were identified. The G10 group in the phylogenetic tree had 13 members, of which 5 were related to the circadian rhythm, accounting for 39%. The G1, G2, G8, G9, G15, G16, G18, G19, G20, G21 and G23 groups had no members associated with the circadian rhythm. Among the 22 differentially expressed MYB transcription factors, 3 members of LHY, RVE1 and RVE8 were core circadian rhythm genes belonging to the G10, G12 and G10 groups, respectively. Real-time fluorescence quantitative PCR was used to detect and validate the expression of the gene transcripts encoding MYB transcription factors associated with the circadian rhythm.

Utilizing single- and double-transfected cell models expressing human organic anion transporter 1 and human cytochrome P450 1A2 to investigate the interactions with ingredients of herbal medicines.

1. Cell models expressing human drug transporters and enzymes are useful tools to understand the process of drug disposition in vitro. However, no study on transfected cells stably co-expressing human organic anion transporter 1 (hOAT1) and/or human cytochrome P450 1A2 (hCYP1A2) is available. In this study, cell models stably expressing hOAT1 and/or hCYP1A2 were established, and were used to investigate the interactions of ingredients of herbal medicines (IHMs) with hOAT1 and/or hCYP1A2. 2. The MDCK cells were stable transfected with recombinant plasmids expressing hOAT1 and/or hCYP1A2. Cellular uptake assay and CYP450 activity assay showed that the transfected cells were available. A marked high expression of hOAT1 and hCYP1A2 mRNA was also validated by quantitative RT-PCR. Totally 6 IHMs which significantly inhibited the activity of hOAT1 were screened out by employing hOAT1 expressing cells. The contribution of hOAT1 and hCYP1A2 to the toxicity of aristolochic acid I (AAI) was further determined. Compared to mock cells, all transfected cells showed a decrease in viability after being treated with AAI. 3. A method to establish transfected cell expressing drug metabolism enzymes and/or transporters was provided in our study. Three IHMs (dihydrotanshinone I, cryptotanshinone, and tanshinone I) were confirmed as novel inhibitors of hOAT1. Furthermore, a synergistic effect of hOAT1 and hCYP1A2 on AAI-induced toxicity was also observed in this investigation.

Coherence evolution of partially coherent beams carrying optical vortices propagating in non-Kolmogorov turbulence.

Based on partially coherent Bessel-Gaussian beams (BGBs), the coherence evolution of the partially coherent beams carrying optical vortices in non-Kolmogorov turbulence is investigated in detail. The analytical formulas for the spatial coherence length of partially coherent BGBs with optical vortices in non-Kolmogorov turbulence have been derived by using the combination of a coherence superposition approximation of decentered Gaussian beams and the extended Huygens-Fresnel principle. The influences of beam and turbulence parameters on spatial coherence are investigated by numerical examples. Numerical results reveal that the coherence of the partially coherent laser beam with vortices is independent of the optical vortices, and the spatial correlation length of the beams does not decrease monotonically during propagation in non-Kolmogorov turbulence. Within a certain propagation distance, the coherence of the partially coherent beam will improve, and the improvement of the coherence of the partially coherent beams is closely related to the beam and turbulence parameters.

Nonlinear optical phonon spectroscopy revealing polaronic signatures of the LaAlO3/SrTiO3 interface.

We report the direct observation of lattice phonons confined at LaAlO3/SrTiO3 (LAO/STO) interfaces and STO surfaces using the sum-frequency phonon spectroscopy. This interface-specific nonlinear optical technique unveiled phonon modes localized within a few monolayers at the interface, with inherent sensitivity to the coupling between lattice and charge degrees of freedom. Spectral evolution across the insulator-to-metal transition at LAO/STO interface revealed an electronic reconstruction at the subcritical LAO thickness, as well as strong polaronic signatures upon formation of the two-dimensional electron gas. We further discovered a characteristic lattice mode from interfacial oxygen vacancies, enabling us to probe such important structural defects in situ. Our study provides a unique perspective on many-body interactions at the correlated oxide interfaces.

Tumor-Derived Small Extracellular Vesicles Inhibit the Efficacy of CAR T Cells against Solid Tumors.

Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable success in the treatment of hematologic malignancies. Unfortunately, it has limited efficacy against solid tumors, even when the targeted antigens are well expressed. A better understanding of the underlying mechanisms of CAR T-cell therapy resistance in solid tumors is necessary to develop strategies to improve efficacy. Here we report that solid tumors release small extracellular vesicles (sEV) that carry both targeted tumor antigens and the immune checkpoint protein PD-L1. These sEVs acted as cell-free functional units to preferentially interact with cognate CAR T cells and efficiently inhibited their proliferation, migration, and function. In syngeneic mouse tumor models, blocking tumor sEV secretion not only boosted the infiltration and antitumor activity of CAR T cells but also improved endogenous antitumor immunity. These results suggest that solid tumors use sEVs as an active defense mechanism to resist CAR T cells and implicate tumor sEVs as a potential therapeutic target to optimize CAR T-cell therapy against solid tumors. SIGNIFICANCE: Small extracellular vesicles secreted by solid tumors inhibit CAR T cells, which provide a molecular explanation for CAR T-cell resistance and suggests that strategies targeting exosome secretion may enhance CAR T-cell efficacy. See related commentary by Ortiz-Espinosa and Srivastava, p. 2637.

HRS mediates tumor immune evasion by regulating proteostasis-associated interferon pathway activation.

By sorting receptor tyrosine kinases into endolysosomes, the endosomal sorting complexes required for transport (ESCRTs) are thought to attenuate oncogenic signaling in tumor cells. Paradoxically, ESCRT members are upregulated in tumors. Here, we show that disruption of hepatocyte growth factor-regulated tyrosine kinase substrate (HRS), a pivotal ESCRT component, inhibited tumor growth by promoting CD8+ T cell infiltration in melanoma and colon cancer mouse models. HRS ablation led to misfolded protein accumulation and triggered endoplasmic reticulum (ER) stress, resulting in the activation of the type I interferon pathway in an inositol-requiring enzyme-1α (IRE1α)/X-box binding protein 1 (XBP1)-dependent manner. HRS was upregulated in tumor cells with high tumor mutational burden (TMB). HRS expression associates with the response to PD-L1/PD-1 blockade therapy in melanoma patients with high TMB tumors. HRS ablation sensitized anti-PD-1 treatment in mouse melanoma models. Our study shows a mechanism by which tumor cells with high TMB evade immune surveillance and suggests HRS as a promising target to improve immunotherapy.

Upregulation of exosome secretion from tumor-associated macrophages plays a key role in the suppression of anti-tumor immunity.

Macrophages play a pivotal role in tumor immunity. We report that reprogramming of macrophages to tumor-associated macrophages (TAMs) promotes the secretion of exosomes. Mechanistically, increased exosome secretion is driven by MADD, which is phosphorylated by Akt upon TAM induction and activates Rab27a. TAM exosomes carry high levels of programmed death-ligand 1 (PD-L1) and potently suppress the proliferation and function of CD8+ T cells. Analysis of patient melanoma tissues indicates that TAM exosomes contribute significantly to CD8+ T cell suppression. Single-cell RNA sequencing analysis showed that exosome-related genes are highly expressed in macrophages in melanoma; TAM-specific RAB27A expression inversely correlates with CD8+ T cell infiltration. In a murine melanoma model, lipid nanoparticle delivery of small interfering RNAs (siRNAs) targeting macrophage RAB27A led to better T cell activation and sensitized tumors to anti-programmed cell death protein 1 (PD-1) treatment. Our study demonstrates tumors use TAM exosomes to combat CD8 T cells and suggests targeting TAM exosomes as a potential strategy to improve immunotherapies.

Ultrahigh Resolution Pixelated Top-Emitting Quantum-Dot Light-Emitting Diodes Enabled by Color-Converting Cavities.

Realizing pixelated quantum-dot light-emitting diodes for high-resolution displays remains a challenging task because of the difficulty of fine patterning the quantum-dots. In this study, instead of patterning the quantum-dots, the color-converting cavities for realizing high-resolution pixelated emission are developed. By defining the thicknesses of the transparent electrodes (phase tuning layers) through a photolithographic process, the resultant cavities can selectively convert the unpatterned quantum-dot white emission as saturated red, green, and blue emission with a brightness of 22170, 51930, and 3064 cd m-2 at 5.5 V, respectively. The developed method enables the realization of ultrahigh density red, green, and blue emission for a display with a resolution of ≈1700 pixel-per-inch and a color gamut of 111% National Television System Committee; together with the advantages of quantum-dot patterning-free, color-filter-free and high brightness, the demonstrated architecture could find potential applications in various displays ranging from cell phone to emerging virtual reality and augmented reality displays.

Risk Factors Identification of Unsafe Acts in Deep Coal Mine Workers Based on Grounded Theory and HFACS.

The risk factors affecting workers' unsafe acts were comprehensively identified by Human Factors Analysis and Classification System (HFACS) and grounded theory based on interview data and accident reports from deep coal mines. Firstly, we collected accident case and field interview data from deep coal mines issued by authoritative institutions. Then, the data were coded according to grounded theory to obtain relevant concepts and types. The HFACS model was used to classify the concepts and categories. Finally, the relationship between core and secondary categories was sorted out by applying a story plot. The results show that risk factors of unsafe acts of deep coal mine workers include environmental factors, organizational influence, unsafe supervision and unsafe state of miners, and the main manifestations of unsafe acts are errors and violations. Among them, the unsafe state of miners is the intermediate variable, and other factors indirectly affect risky actions of coal miners through unsafe sates. Resource management, organizational processes and failure to correct problems are the top three risk factors that occur more frequently in unsafe acts. The three most common types of unsafe act are unreasonable labor organization, failure to enforce rules, and inadequate technical specifications. By combining grounded theory and the HFACS framework to analyze data, risk factors for deep coal miners can be quickly identified, and more precise and comprehensive conceptual models of risk factors in unsafe acts of deep coal miners can be obtained.

Influencing Factors, Formation Mechanism, and Pre-control Methods of Coal Miners' Unsafe Behavior: A Systematic Literature Review.

Coal mine accidents are mainly caused by the unsafe behavior of workers. Studying workers' unsafe behaviors can help in regulating such behaviors and reducing the incidence of accidents. However, there is a dearth of systematic literature review in this area, which has hindered mine managers from fully understanding the unsafe behavior of workers. This study aims to address this research gap based on the literature retrieved from the Web of Science. First, a descriptive statistical analysis is conducted on the year, quantity, publications, and keywords of the literature. Second, the influencing factors, formation mechanism, and pre-control methods of coal miners' unsafe behavior are determined and discussed, and the research framework and future research directions of this study are proposed. The study results will help mine safety managers fully understand the influencing factors, formation mechanism, and pre-control methods of workers' unsafe behavior, and lay a theoretical foundation for the future research direction in this field.

Comprehensive Evaluation of Deep Coal Miners' Unsafe Behavior Based on HFACS-CM-SEM-SD.

The unsafe behavior of miners seriously affects the safety of deep mining. A comprehensive evaluation of miners' unsafe behavior in deep coal mines can prevent coal mine accidents. This study combines HFACS-CM, SEM, and SD models to evaluate miners' unsafe behaviors in deep coal mining. First, the HFACS-CM model identifies the risk factors affecting miners' unsafe behavior in deep coal mines. Second, SEM was used to analyze the interaction between risk factors and miners' unsafe behavior. Finally, the SD model was used to simulate the sensitivity of each risk factor to miners' unsafe behavior to explore the best prevention and control strategies for unsafe behavior. The results showed that (1) environmental factors, organizational influence, unsafe supervision, and unsafe state of miners are the four main risk factors affecting the unsafe behavior of miners in deep coal mines. Among them, the unsafe state of miners is the most critical risk factor. (2) Environmental factors, organizational influence, unsafe supervision, and the unsafe state of miners have both direct and indirect impacts on unsafe behaviors, and their immediate effects are far more significant than their indirect influence. (3) Environmental factors, organizational influence, and unsafe supervision positively impact miners' unsafe behavior through the mediating effect of miners' unsafe states. (4) Mental state, physiological state, business abilities, resource management, and organizational climate were the top five risk factors affecting miners' unsafe behaviors. Taking measures to improve the adverse environmental factors, strengthening the organization's supervision and management, and improving the unsafe state of miners can effectively reduce the risk of miners' unsafe behavior in deep coal mines. This study provides a new idea and method for preventing and controlling the unsafe behavior of miners in deep coal mines.

Effects of Online Learning on College Students in Eastern China: A Structural Equation Model.

With the spread of COVID-19 worldwide, online education is rapidly catching on, even in some underdeveloped countries and regions. Based on Bandura's ternary learning theory and literature review, this paper takes online learning of college students as the research object and conducts an empirical survey on 6,000 college students in East China. Based on literature review and factor analysis and structural equation model, this paper discusses the relationship among learning cognition, learning behavior, and learning environment in online learning of college students. The learning behavior includes interactive communication, self-discipline mechanism, classroom learning, and study after class. The learning environment includes teaching ability, knowledge system, platform support, process control, and result evaluation; learning cognition includes learning motivation, information perception, and adaptability. It is found that the learning environment has a significant positive impact on learning behavior, and learning cognition has a significant positive impact on learning behavior. It is uncertain whether the learning environment significantly impacts learning cognition. At the learning environment level, the teaching ability (0.59) has the most significant impact on the learning environment, followed by result evaluation (0.42), platform support (0.40), process control (0.33), and knowledge system (0.13). In terms of the influence on learning behavior, classroom learning has the most significant impact (0.79), followed by self-discipline mechanism (0.65), study after class (0.54), and interactive communication (0.44). In terms of learning cognition, information perception (0.62) has the most significant influence, followed by learning motivation (0.50) and adaptability (0.41). This paper suggests strengthening the construction of platforms and digital resources to create a more competitive learning environment. Improve process management and personalized online services, constantly stimulate students' enthusiasm for independent online learning, and cultivate students' online independent learning ability to promote the sustainable and healthy development of online education.

Research on the Construction of a Comprehensive Evaluation Model of Psychological Factors in Coal Mine Workers' Safety: Investigation and Analysis of 1,500 Miners in East China.

With China's economic and social development entering a new era, the improvement of miners' living standards and safety production conditions in coal mine are bound to have a new impact on the safety needs of miners. In order to explore the structural changes of miners' safety demands in the new era, this research adopts the second-order confirmatory factor analysis method to investigate miners from six coal mining enterprises based on Koffka's cognitive psychology theory. Firstly, according to the interaction between the behavioral environment and the self-regulation of coal miners, six potential variables affecting miners' safety psychology, such as material satisfaction, non-skill internal causes, professionalism, emotional attribution, safety atmosphere, and organizational management, are selected. Then, each potential variable is subdivided into 3 observation variables, for a total of 18 observation variables, and a 3-tier comprehensive structural model of miners' safety psychology is constructed that takes into account both evaluation and path integration. The results showed that, affected by the interaction of various potential variables, the degree and intensity of the influence of each factor on miners' safety psychology were different. Among them, emotional attribution was the most significant factor affecting miners' safety psychology, while the influence of organizational management was slightly less important than emotional attribution. Organizational management had a positive impact on material satisfaction and non-skill internal factors. Occupational literacy, material satisfaction, and safety atmosphere had strong impacts on miners' safety psychology. But the impact of non-skill factors on miners' safety psychology was lower than other factors, which is different to previous studies on this aspect.

ICAM-1-mediated adhesion is a prerequisite for exosome-induced T cell suppression.

Tumor-derived extracellular vesicles (TEVs) suppress the proliferation and cytotoxicity of CD8+ T cells, thereby contributing to tumor immune evasion. Here, we report that the adhesion molecule intercellular adhesion molecule 1 (ICAM-1) co-localizes with programmed death ligand 1 (PD-L1) on the exosomes; both ICAM-1 and PD-L1 are upregulated by interferon-γ. Exosomal ICAM-1 interacts with LFA-1, which is upregulated in activated T cells. Blocking ICAM-1 on TEVs reduces the interaction of TEVs with CD8+ T cells and attenuates PD-L1-mediated suppressive effects of TEVs. During this study, we have established an extracellular vesicle-target cell interaction detection through SorTagging (ETIDS) system to assess the interaction between a TEV ligand and its target cell receptor. Using this system, we demonstrate that the interaction of TEV PD-L1 with programmed cell death 1 (PD-1) on T cells is significantly reduced in the absence of ICAM-1. Our study demonstrates that ICAM-1-LFA-1-mediated adhesion between TEVs and T cells is a prerequisite for exosomal PD-L1-mediated immune suppression.

The role of non-coding RNAs in ABC transporters regulation and their clinical implications of multidrug resistance in cancer.

INTRODUCTION: Multi-drug resistance (MDR) is a hindrance toward the successful treatment of cancers. The primary mechanism that gives rise to acquired chemoresistance is the overexpression of adenosine triphosphate-binding cassette (ABC) transporters. The dysregulation of non-coding RNAs (ncRNAs) is a widely concerned reason contributing to this phenotype. AREAS COVERED: In this review, we describe the role of intracellular and exosomal ncRNAs including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in ABC transporters-induced tumor MDR. Meanwhile, we will introduce the potential therapeutic strategies which reverse MDR in terms of reducing the expression of ABC transporters via targeting ncRNAs, like nucleic acid delivery with nanoparticles as well as miRNAs-targeted small molecular compounds. EXPERT OPINION: The dysregulated ncRNAs-mediated overexpression of ABC transporters in chemo-resistant cancer is not negligible. Finding out the underlying mechanism may provide a theoretical basis for clinical therapy of cancer MDR, and the emergence of new approaches for gene therapy targeting ncRNAs to suppress ABC transporters makes reversing cancer MDR possible despite its clinical application requires further investigations. Also, the discovered ncRNAs regulating ABC transporters in chemo-resistant cancers are just a tip of the iceberg of the genetic transcripts, especially for circRNAs, which justify more concern.Abbreviations: MDR, multi-drug resistance; ABC, adenosine triphosphate-binding cassette; NcRNAs, non-coding RNAs; MiRNAs, microRNAs; LncRNAs, long non-coding RNAs; CircRNAs, circular RNAs; CeRNAs, competing endogenous RNAs; 3'UTR, 3'-untranslated regions; SLC, solute carrier; ABCB1/MDR1, ABC subfamily B member 1; ABCG2/BCRP, ABC subfamily G member 2; ABCCs/MRPs, ABC subfamily C 1 to 12; DLL1: Delta-like protein 1; DTX, docetaxel; DOX/ADM/ADR, doxorubicin/adriamycin; PTX, paclitaxel; VBL, vinblastine; VCR, vincristine; MTX, methotrexate; CDDP/DDP, cisplatin/cis-diaminedichloroplatinum; OXA/L-OHP, oxaliplatin; TMZ, temozolomide; 5-FU, 5-fluorouracil; MTA, pemetrexed; NSCLC, non-small cell lung carcinoma; HCC, hepatocellular carcinoma; CRC, colorectal carcinoma; RB, retinoblastoma; RCC, renal cell carcinoma; OS, osteosarcoma; PDAC, pancreatic ductal adenocarcinoma; TNBC, triple-negative breast cancer.

LncRNA regulation: New frontiers in epigenetic solutions to drug chemoresistance.

Long-noncoding RNAs (lncRNAs) have been shown to participate in sensitizing or de-sensitizing cancer cells to chemical drugs during cancer therapeutics. Notably, a plethora of lncRNAs have been confirmed to be associated with epigenetic controllers and regulate histone protein modification or DNA methylation states in the process of gene transcription. This correlation between lncRNAs and epigenetic regulators can induce the expression of core genes to trigger drug resistance. In addition, epigenetic signatures are considered to be effective and attractive biomarkers for monitoring drug therapeutic effects because they are inheritable, dynamic, and reversible. Therefore, the regulatory mechanism between lncRNAs and epigenetic machinery can serve as a novel indicator and target to overcome or reverse drug resistance in cancer therapy. In this review, we also presented a curated selection of computational tools (including online databases and network analysis) in the area of epigenetics. A classic workflow for lncRNA expression network analysis is presented, providing guidance for non-bioinformaticians to identify significant correlation between lncRNAs and other biomolecules.

miR-224-5p Contained in Urinary Extracellular Vesicles Regulates PD-L1 Expression by Inhibiting Cyclin D1 in Renal Cell Carcinoma Cells.

The abundant miRNAs in urinary extracellular vesicles (EVs) represent ideal reservoirs for biomarker discovery, especially in renal cell carcinoma (RCC). However, the content and biological functions of microRNAs contained in urinary EVs in RCC remain ambiguous. In this study, urinary EVs were isolated and characterized from RCC patients and healthy volunteers. Differentially expressed microRNAs in urinary EVs were screened by small RNA sequencing. The target gene and biological functions of selected microRNAs were investigated through multifaceted methods. Results indicated that miR-224-5p was significantly upregulated in urinary EVs of RCC patients compared to healthy volunteers. The overexpression of miR-224-5p inhibited RCC cell proliferation and induced cell cycle arrest. The gene CCND1 encoding cyclin D1 was identified as a direct target of miR-224-5p via prediction and validation. Moreover, the invasive and metastatic abilities of RCC cells were enhanced by miR-224-5p. Interestingly, miR-224-5p also increased the stability of PD-L1 protein by inhibiting CCND1. This effect could be transmitted via EVs and further promoted the resistance of RCC cells to T cell-dependent toxicity. In summary, urinary EVs containing miR-224-5p were identified as a potential biomarker in RCC. Regulation of PD-L1 protein expression by miR-224-5p through suppressing CCND1 elucidates new roles of miR-224-5p in RCC progression.

Regulation of MRP4 Expression by circHIPK3 via Sponging miR-124-3p/miR-4524-5p in Hepatocellular Carcinoma.

Multidrug resistance-associated protein 4 (MRP4), a member of the adenosine triphosphate (ATP) binding cassette transporter family, pumps various molecules out of the cell and is involved in cell communication and drug distribution. Several studies have reported the role of miRNAs in downregulating the expression of MRP4. However, regulation of MRP4 by circular RNA (circRNA) is yet to be elucidated. In this study, MRP4 was significantly upregulated in hepatocellular carcinoma (HCC) tissues compared to the adjacent noncancerous tissues. Computational prediction, luciferase reporter assay and miRNA transfection were used to investigate the interaction between miRNAs and MRP4. miR-124-3p and miR-4524-5p reduced the expression of MRP4 at the protein but not mRNA level. Circular RNA in vivo precipitation and luciferase reporter assays demonstrated that circHIPK3, as a competitive endogenous RNA, binds with miR-124-3p and miR-4524-5p. Further, knockdown of circHIPK3 resulted in downregulation of MRP4 protein, whereas cotransfection of circHIPK3-siRNA and miR-124-3p or miR-4524-5p inhibitors restored its expression. In conclusion, we report that miR-4524-5p downregulates the expression of MRP4 and circHIPK3 regulates MRP4 expression by sponging miR-124-3p and miR-4524-5p for the first time. Our results may provide novel insights into the prevention of MRP4-related proliferation and multiple drug resistance in HCC.