Organic photoelectrochemical transistor aptasensor for dual-mode detection of DEHP with CRISPR-Cas13a assisted signal amplification.

Emerging organic photoelectrochemical transistors (OPECTs) with inherent amplification capabilities, good biocompatibility and even self-powered operation have emerged as a promising detection tool, however, they are still not widely studied for pollutant detection. In this paper, a novel OPECT dual-mode aptasensor was constructed for the ultrasensitive detection of di(2-ethylhexyl) phthalate (DEHP). MXene/In2S3/In2O3 Z-scheme heterojunction was used as a light fuel for ion modulation in sensitive gated OPECT biosensing. A transistor system based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) converted biological events associated with photosensitive gate achieving nearly a thousand-fold higher current gain at zero bias voltage. This work quantified the target DEHP by aptamer-specific induction of CRISPR-Cas13a trans-cutting activity with target-dependent rolling circle amplification as the signal amplification unit, and incorporated the signal changes strategy of biocatalytic precipitation and TMB color development. Combining OPECT with the auxiliary validation of colorimetry (CM), high sensitivity and accurate detection of DEHP were achieved with a linear range of 0.1 pM to 200 pM and a minimum detection limit of 0.02 pM. This study not only provides a new method for the detection of DEHP, but also offers a promising prospect for the gating and application of the unique OPECT.

MXene-Enhanced Bi2S3/CdIn2S4 Heterojunction Photosensitive Gate for DEHP Detection in a Signal-On OPECT Aptamer Biosensor.

Organic electrochemical transistors with signal amplification and good stability are expected to play a more important role in the detection of environmental pollutants. However, the bias voltage at the gate may have an effect on the activity of vulnerable biomolecules. In this work, a novel organic photoelectrochemical transistor (OPECT) aptamer biosensor was developed for di(2-ethylhexyl) phthalate (DEHP) detection by combining photoelectrochemical analysis with an organic electrochemical transistor, where MXene/Bi2S3/CdIn2S4 was employed as a photoactive material, target-dependent DNA hybridization chain reaction was used as a signal amplification unit, and Ru(NH3)63+ was selected as a signal enhancement molecule. The poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based OPECT biosensor modulated by the MXene/Bi2S3/CdIn2S4 photosensitive material achieved a high current gain of nearly a thousand times at zero bias voltage. The developed signal-on OPECT sensing platform realized sensitive and specific detection of DEHP, with a detection range of 1-200 pM and a minimum detection limit of 0.24 pM under optimized experimental conditions, and its application to real water samples was also evaluated with satisfactory results. Hence, the construction of this OPECT biosensing platform not only provides a promising tool for the detection of DEHP but also reveals the great potential of the OPECT application for the detection of other environmental toxins.

Ascorbic Acid Induced the Improved Oxygen Vacancy Defects of Bi4O5Br2 and Its Application on Photoelectrochemical Detection of DNA Demethylase MBD2 with Improved Detection Sensitivity.

Oxygen vacancy defects (OVs) are one of the main strategies for nanomaterials modification to improve the photoactivity, but current methods for fabricating OVs are usually complicated and harsh. It is important to develop simple, rapid, safe, and mild methods to fabricate OVs. By studying the effects of different weak reducing agents, the concentration of the reducing agent and the reaction time on fabrication of OVs, it is found that L-ascorbic acid (AA) gently and rapidly induces the increase of OVs in Bi4O5Br2 at room temperature. The increased OVs not only improve the adsorption of visible light, but also enhance the photocurrent response. Based on this, the preparation of OVs in Bi4O5Br2 is employed to the development of a photoelectrochemical biosensor for the detection of DNA demethylase of methyl-CpG binding domain protein 2 (MBD2). The biosensor shows a wide linear range of 0.1-400 ng mL-1 and a detection limit as low as 0.03 ng mL-1 (3σ). In addition, the effect of plasticizers on MBD2 activity is evaluated using this sensor. This work not only provides a novel method to prepare OVs in bismuth rich materials, but also explores a new novel evaluation tool for studying the ecotoxicological effects of contaminants.

Clinical significance and correlation of compliance to thirst in maintenance hemodialysis patients.

BACKGROUND: The main treatment method for end-stage renal disease (ESRD) is maintenance hemodialysis (MHD). With the continuous improvement of dialysis technology, the survival period of MHD patients has been effectively prolonged, but dialysis technology still cannot completely replace renal function. OBJECTIVE: To study the dietary compliance and its correlation with thirst in MHD patients and to provide guidance for clinical development of corresponding intervention countermeasures. METHODS: A total of 90 patients who received MHD treatment from March 2021 to March 2022 were selected as objects. The Renal Adherence Attitudes Questionnaire (RAAQ) and the Renal Adherence Behaviour Questionnaire (RABQ) were used to analyze the dietary compliance and thirst status of patients. Pearson correlation analysis was used to analyze the correlation between diet compliance and thirst. RESULTS: Positive correlations were found between VAS and DTI, SXI and TDS (P< 0.05). Social restrictive attitude was positively correlated with VAS, DTI, SXI, TDS, acceptance attitude and compliance in facing difficulties (P< 0.05), and negatively correlated with self-care compliance (r=-0.35, P< 0.05). Health attitude was positively correlated with VAS, DTI and SXI (P< 0.05). Acceptance attitude was positively correlated with DTI, SXI and TDS (P< 0.05). High RAAQ was associated with high VAS (b= 0.11, 95% CI: 0.05, 0.18), DTI (b= 0.28, 95% CI: 0.17, 0.38), SXI (b= 0.24, 95% CI: 0.14, 0.34) and TDS (b= 0.26, 95% CI: 0.13, 0.4). CONCLUSION: The overall performance of dietary compliance in patients with MHD is at a moderate level, and dietary compliance is negatively correlated with disease perception.

NAD+ mediated photoelectrochemical biosensor for histone deacetylase Sirt1 detection based on CuO-BiVO4-AgNCs heterojunction and hybridization chain reaction amplification.

BACKGROUND: Histone deacetylate Sirt1 has been involved in many important biological processes and is closely related to the occurrence and development of many diseases. Therefore, the accurate detection of Sirt1 is of great significance for the diagnosis and treatment of diseases caused by Sirt1 and the development of related drugs. RESULTS: In this work, a photoelectrochemical biosensor was developed for Sirt1 detection based on the NAD + mediated Sirt1 recognition and E. Coli DNA ligase activity. CuO-BiVO4p-n heterojunction was employed as the photoactive material, rolling circle amplification (RCA), hybridization chain reaction (HCR) and AgNCs were used as triple signal amplifications. As a bifunctional cofactor, NAD+ played a crucial role for Sirt1 detection, where the peptide deacetylation catalyzed by Sirt1 consumed NAD+, and the decreased amount of NAD + inhibited the activity of E. Coli DNA ligase, leading to the failure on RCA reaction, and improving the HCR reaction. Finally, AgNCs were generated using C-rich DNA as carrier. The surface plasmon effect of AgNCs and its heterojunction with CuO and BiVO4 accelerated the transfer rate of photogenerated carriers and improved the photocurrent signal. When the detection range was 0.001-200 nM, the detection limit of the biosensor was 0.76 pM (S/N = 3). SIGNIFICANCE: The applicability of the method was evaluated by studying the effects of known inhibitors nicotinamide and environmental pollutant halogenated carbazole on Sirt1 enzyme activity. The results showed that this method can be used as a new platform for screening Sirt1 enzyme inhibitors, and also provided a new biomarker for evaluating the ecotoxicological effects of environmental pollutants.

Photoelectrochemical biosensor for DNA demethylase detection based on enzymatically induced double-stranded DNA digestion by endonuclease-exonuclease system and Bi4O5Br2-Au/CdS photoactive material.

A novel photoelectrochemical (PEC) biosensor for the detection of DNA demethylase MBD2 was developed based on Bi4O5Br2-Au/CdS photosensitive material. Bi4O5Br2 was firstly modified with gold nanoparticles (AuNPs), following with the modification onto the ITO electrode with CdS to realize the strong photocurrent response as a result of AuNPs had good conductibility and the matched energy between CdS and Bi4O5Br2. In the presence of MBD2, double-stranded DNA (dsDNA) on the electrode surface was demethylated, which triggered the digestion activity of endonuclease HpaII to cleave dsDNA and induced the further cleavage of the dsDNA fragment by exonuclease III (Exo III), causing the release of biotin labeled dsDNA and inhibiting the immobilization of streptavidin (SA) onto the electrode surface. As a results, the photocurrent was increased greatly. However, in the absence of MBD2, HpaII digestion activity was inhibited by DNA methylation modification, which further caused the failure in the release of biotin, leading to the successful immobilization of SA onto the electrode to realize a low photocurrent. The sensor had a detection of 0.3-200 ng/mL and a detection limit was 0.09 ng/mL (3σ). The applicability of this PEC strategy was assessed by studying the effect of environmental pollutants on MBD2 activity.

Antibody-free photoelectrochemical biosensor for DNA carboxylation detection based on SnS2@Ti3C2 heterojunction.

As an important epigenetic modification, 5-carboxycytosine (5caC) played an important role in gene regulation, cell differentiation and growth. 5caC existed in many cells and tissues, but it was highly similar to the structure of other cytosine derivatives and had less content in the genome. Therefore, it was urgent to develop a sensitive and highly selective trace biosensor to detect 5caC. A novel photoelectrochemical biosensor was fabricated for 5-carboxy-2'-deoxycytidine-5'-triphosphate (5cadCTP) detection, where SnS2@Ti3C2 nanocomposite was employed as photoactive material, polyethyleneimine was used as 5cadCTP recognition and capture reagent, and Ru(NH3)63+ was used as photosensitizer for signal amplification. Due the good conductivity of Ti3C2 MXene and the matched energy band between Ti3C2 MXene and SnS2, SnS2@Ti3C2 nanocomposite presented strong photoactivity, which was beneficial to the high detection sensitivity. For specific recognition of 5cadCTP, the covalent interaction of -NH2 in 5cadCTP with -COOH on the substrate electrode was used, which was beneficial to the high detection selectivity. A broad linear relationship between photocurrent and 5cadCTP concentration was observed ranging from 1 pM to 0.2 µM. The low detection limit of 260 fM was achieved. The developed method has high detection specificity and can even distinguish 5caC with its derivatives. In addition, the applicability was evaluated by detecting the content change of 5caC in the genomic DNA of rice seedlings after cultured with environmental pollutants. This work provides a novel platform for 5cadCTP detection, and it can also be applied to detect other cytosine derivatives with suitable recognition strategies.

Antibody-free photoelectrochemical strategy for simultaneous detection of methylated RNA, METTL3/METTL14 protein and MazF protein based on enhanced photoactivity of MoSe2-BiOI nanocomposite.

Taking advantages of the catalytic activity of METTL3/METTL14 protein towards adenine methylation in RNA sequence and the specific digestion activity of MazF protein towards unmethylated RNA sequence containing ACA bases, a novel photoelectrochemical biosensor was constructed for simultaneous detection of RNA methylation, METTL3/METTL14 protein and MazF protein. MoSe2-BiOI nanocomposite was prepared and considered as photoactive material, catalytic hairpin assembly strategy and in situ generation of electron donors catalyzed by polyaspartic acid-loaded alkaline phosphatase technique were employed as signal amplification. Under the optimum conditions, the detection ranges of methylated RNA, METTL3/METTL14 protein and MazF protein were 0.001-50 nM, 0.001-25 ng/µL, and 0.001-10 U/mL, respectively. The corresponding detection limits were 0.46 pM, 0.51 pg/µL and 0.42 U/µL with S/N = 3. In addition, the effect of drugs and composite pollutants on the activities of MazF proteins was assessed, proving the applicability of the developed method in the field of drug screening for MazF-related diseases. Moreover, the effects of pollutants on the activity of METTL3/METTL14 were also preliminarily explored, providing new information on pathogenic mechanism of pollutants.

Photoelectrochemical Biosensor for Histone Deacetylase Sirt1 Detection Based on Polyaspartic Acid-Engaged and Triggered Redox Cycling Amplification and Enhanced Photoactivity of BiVO4 by Gold Nanoparticles and SnS2.

A photoelectrochemical (PEC) biosensor was established for histone deacetylase Sirt1 detection based on the polyaspartic acid (PASP)-mediated redox cycling amplification and Sirt1 catalysis deacetylation-triggered recognition of the deacetylated substrate peptide, using PASP as the recognition reagent. After BiVO4 was composited with gold nanoparticles and SnS2, the photoactivity of the composite was greatly enhanced due to the matched energy band structure. Under the catalysis of Sirt1 enzyme, the acetylated substrate peptide was deacetylated to obtain a positive peptide, which was recognized by negative PASP. In addition to the recognition function, PASP also played other triple roles. First, PASP interacted with the positive peptide to form a double-stranded structure, which led to the electrode interface changing from irregular to regular, resulting in an improved PEC response. Second, PASP was involved into redox cycle amplification due to its reduction to dehydroascorbic acid. Further, it was used for repeated preparation of ascorbic acid to provide electron donors. This process enhanced the PEC response. Third, based on the matched energy band with BiVO4, PASP effectively improved the photoactivity of BiVO4. With multiplex signal amplification, the PEC biosensor showed a wide linear range (1.83-1830 pM) and high detection sensitivity with a low detection limit of 0.732 pM (S/N = 3). The applicability of this method was evaluated by studying the effects of a known inhibitor of nicotinamide and the heavy metal ions of Cd2+ and Pb2+ on Sirt1 enzyme activity, and the results showed that this method not only provided a new platform for screening Sirt1 enzyme inhibitors but also provided new biomarkers for evaluating the ecotoxicological effects of environmental pollutants.

MXene Enhanced Photoactivity of Bi2O3/Bi2S3 Heterojunction with G-wire Superstructure for Photoelectrochemical Detection of TET1 Protein.

Ten-eleven translocation 1 (TET1) protein has the potential to accelerate the oxygenation of 5-methylcytosine to 5-hydroxymethylcytosine (5hmC); then the -CH2OH of 5hmC can further covalently react with -SH catalyzed by M.HhaI methyltransferase. A brand-new photoelectrochemical (PEC) detection technique for the TET1 protein was created in light of this. For this objective, the Bi2O3/Bi2S3 heterojunction was first prepared by a one-pot hydrothermal method and served for photosensitive materials. For further enhancing the photoactivity, Bi2O3/Bi2S3 was blended with MXene to form an energy band-matched structure, thus improving the migration kinetics of photogenerated carriers. For achieving a high sensitivity of detection, a DNA Walker incorporated with the nicking endonuclease (Nb.BbvCI enzyme)-assisted signal amplification strategy was presented to output exponential G-quadruplex fragments. Self-assembly of the free G-quadruplex sequence into a G-wire superstructure with the assistance of Mg2+ provided more loading sites for MB and amplified the PEC signal. The linear range of the biosensor was 0.1-10 µg/mL with a detection limit of 0.024 µg/mL (S/N = 3) for TET1 protein under optimal experimental conditions. The suitability of the proposed method was evaluated by inhibitor screening experiments and the influence of environmental degradation on the activity of TET1 protein.

Investigation of the effect of antibiotics on 5-formylcytosine content in mazie seedling tissues based on photoelectrochemical biosensor.

Given the improved photoactivity of Bi2S3 by MXene, an article photoelectrochemical biosensor was designed for 5-formyl-2'-deoxycytidine (5fdCTP) detection, where Bi2S3: MXene was selected as photoactive material, polydopamine was used as solid electron donor and 5fdCTP capture reagent, calcined ZIF-8(C-ZIF-8) was chosen as the artificial enzyme. With the catalyzed by C-ZIF-8, 4-chloro-1-naphthol was allegro oxidized by H2O2 to form the insoluble benzo-4-chlorohexadienone, and then deposited on the surface of the electrode, Resulting in a decrease of the PEC response. Under the optimum conditions, the sensor has a linear range of 0.001-200 nM and a detection limit of 0.51 pM (3σ). The suitability of the developed method was appraised by investigating the effect of antibiotics on 5fdCTP content in the genomic DNA of the roots of maize seedlings. As a new detection platform, the application of this approach can be expanded to investigative the impact of other pollutants on the content of 5fdCTP in plant or animal tissues, explore the feasibility of 5fdCTP as a new indicator for the ecotoxicological effect of pollutants, and the photoelectrochemical method as a new assessment technique for the ecotoxicological effects of pollutants.

Engineering NK-92 Cell by Upregulating CXCR2 and IL-2 Via CRISPR-Cas9 Improves Its Antitumor Effects as Cellular Immunotherapy for Human Colon Cancer.

Natural killer (NK) cells have shown good application prospects in adoptive cellular immunotherapy against cancer. However, due to its insufficient infiltration and low activity, the therapeutic effect of infused NK cells has been limited in solid tumors, such as colorectal cancer. It has been proved that tumor-produced chemokines regulate the migration of NK cells expressing corresponding chemokine receptors, and cytokines could enhance the antitumor activity of NK cells. In this study, we innovatively upregulated the expression of chemokine receptor CXC chemokine receptor 2 (CXCR2) and cytokine interleukin (IL)-2 on NK-92 cells using CRISPR-Cas9 gene-editing technology. We demonstrated that overexpressing CXCR2 and IL-2 promotes NK-92 cells to increasingly transfer into tumor sites and achieve stronger cell-killing and proliferation activity. Moreover, the inhibitory effects of gene-edited NK-92 cells on the growth of human colon cancer in vivo were also improved. The tumor burden of tumor-bearing mice was reduced, and their survival time was significantly prolonged. Gene-editing modification NK cells are expected to become a novel and promising tumor treatment strategy.

Characterization of amino acid residues of T-cell receptors interacting with HLA-A*02-restricted antigen peptides.

BACKGROUND: The present study aimed to explore residues' properties interacting with HLA-A*02-restricted peptides on T-cell receptors (TCRs) and their effects on bond types of interaction and binding free energy. METHODS: We searched the crystal structures of HLA-A*02-restricted peptide-TCR complexes from the Protein Data Bank (PDB) database and subsequently collected relevant parameters. We then employed Schrodinger to analyze the bond types of interaction and Gromacs 2019 to evaluate the TCR-antigen peptide complex's molecular dynamics simulation. Finally, we compared the changes of bond types of interaction and binding free energy before and after residue substitution to ensure consistency of the conditions before and after residue substitution. RESULTS: The main sites on the antigen peptides that formed the intermolecular interaction [hydrogen bond (HB) and pi stack] with TCRs were P4, P8, P2, and P6. The hydrophobicity of the amino acids inside or outside the disulfide bond of TCRs may be related to the intermolecular interaction and binding free energy between TCRs and peptides. Residues located outside the disulfide bond of TCR α or ß chains and forming pi stack force played favorable roles in the complex intermolecular interaction and binding free energy. The residues of the TCR α or ß chains that interacted with peptides were replaced by alanine (Ala) or glycine (Gly), and their intermolecular binding free energy of the complex had been improved. However, it had nothing to do with the formation of HB. CONCLUSIONS: The findings of this study suggest that the hydrophobic nature of the amino acids inside or outside the disulfide bonds on the TCR may be associated with the intermolecular interaction and binding between the TCR and polypeptide. The residues located outside the TCR α or ß single-chain disulfide bond and forming the pi-stack force showed a beneficial effect on the intermolecular interaction and binding of the complex. In addition, the part of the residues on the TCR α or ß single chain that produced bond types of interaction with the polypeptide after being replaced by Ala or Gly, the intermolecular binding free energy of the complex was increased, regardless of whether HB was formed.

Transcriptional Factor Yin Yang 1 Promotes the Stemness of Breast Cancer Cells by Suppressing miR-873-5p Transcriptional Activity.

Transcription factor Yin Yang 1 (YY1) is upregulated in multiple tumors and plays essential roles in tumor proliferation and metastasis. However, the function of YY1 in breast cancer stemness remains unclear. Herein, we found that YY1 expression was negatively correlated with the overall survival and relapse-free survival of breast cancer patients and positively correlated with the expression of stemness markers in breast cancer. Overexpression of YY1 increased the expression of stemness markers, elevated CD44+CD24- cell sub-population, and enhanced the capacity of cell spheroid formation and tumor-initiation. In contrast, YY1 knockdown exhibited the opposite effects. Mechanistically, YY1 decreased microRNA-873-5p (miR-873-5p) level by recruiting histone deacetylase 4 (HDAC4) and HDAC9 to miR-873-5p promoter and thus increasing the deacetylation level of miR-873-5p promoter. Sequentially, YY1 activated the downstream PI3K/AKT and ERK1/2 pathways, which have been confirmed to be suppressed by miR-873-5p in our recent work. Moreover, the suppressed effect of YY1/miR-873-5p axis on the stemness of breast cancer cells was partially dependent on PI3K/AKT and ERK1/2 pathways. Finally, it was found that the YY1/miR-873-5p axis is involved in the chemoresistance of breast cancer cells. Our study defines a novel YY1/miR-873-5p axis responsible for the stemness of breast cancer cells.

Overexpressed CXCR4 and CCR7 on the surface of NK92 cell have improved migration and anti-tumor activity in human colon tumor model.

Successive infusion of natural killer cells is increasingly being explored as a treatment for cancer patients. The inadequate homing of natural killer cells into the tumor site resulted in the poor efficacy of natural killer cells on solid tumors. For the adoptive transfer of tumor-directed natural killer cell has been proved effective, it is hypothesized that there must be more association between the tumor-produced chemokines and the natural killer cells-expressed chemokine receptors. Increased CXCL12 and CCL21 could ameliorated colorectal cancer via generating an anti-tumor environment by preferentially attracting natural killer cells which expressed the chemokine receptor CXCR4 and CCR7. This study demonstrated that overexpressed CXCR4 and CCR7 on the surface of NK92 cell enhanced their migration to human colon cells. Moreover, the administration of such natural killer cells resulted in tumor shrinkage and a significantly increased survival of experimental mice when compared to ones undergoing the treatment of xenografts with natural killer cells expressing only the mock control. These suggested that chemokine receptor engineered natural killer cells could be a promising tool to improve adoptive tumor immunotherapy.

Correction to: Transcriptional factor six2 promotes the competitive endogenous RNA network between CYP4Z1 and pseudogene CYP4Z2P responsible for maintaining the stemness of breast cancer cells.

The original article [1] contained an error in Fig. 7c whereby the same flow image was accidentally misused for the second and fourth group.

Transcriptional factor six2 promotes the competitive endogenous RNA network between CYP4Z1 and pseudogene CYP4Z2P responsible for maintaining the stemness of breast cancer cells.

BACKGROUND: The expression of CYP4Z1 and the pseudogene CYP4Z2P has been shown to be specifically increased in breast cancer by our group and others. Additionally, we previously revealed the roles of the competitive endogenous RNA (ceRNA) network mediated by these genes (ceRNET_CC) in breast cancer angiogenesis, apoptosis, and tamoxifen resistance. However, the roles of ceRNET_CC in regulating the stemness of breast cancer cells and the mechanisms through which ceRNET_CC is regulated remain unclear. METHODS: Transcriptional factor six2, CYP4Z1-3'UTR, and CYP4Z2P-3'UTR were stably overexpressed or knocked down in breast cancer cells via lentivirus infection. ChIP-sequencing and RNA-sequencing analysis were performed to reveal the mechanism through which ceRNET_CC is regulated and the transcriptome change mediated by ceRNET_CC. Clinical samples were used to validate the correlation between six2 and ceRNET_CC. Finally, the effects of the six2/ceRNET_CC axis on the stemness of breast cancer cells and chemotherapy sensitivity were evaluated by in vitro and in vivo experiments. RESULTS: We revealed that ceRNET_CC promoted the stemness of breast cancer cells. Mechanistically, six2 activated ceRNET_CC by directly binding to their promoters, thus activating the downstream PI3K/Akt and ERK1/2 pathways. Finally, we demonstrated that the six2/ceRNET_CC axis was involved in chemoresistance. CONCLUSIONS: Our results uncover the mechanism through which ceRNET_CC is regulated, identify novel roles for the six2/ceRNET_CC axis in regulating the stemness of breast cancer cells, and propose the possibility of targeting the six2/ceRNET_CC axis to inhibit breast cancer stem cell (CSC) traits.

MiR-873/PD-L1 axis regulates the stemness of breast cancer cells.

BACKGROUND: Breast cancer stem cells have self-renewal capability and are resistant to conventional chemotherapy. PD-L1 could promote the expression of stemness markers (OCT4 and Nanog) in breast cancer stem cells. However, the mechanisms by which PD-L1 regulates the stemness of breast cancer cells and PD-L1 is regulated in breast cancer cells are still unclear. METHODS: Lentivirus infection was used to construct stable cell lines. The correlation between PD-L1 and stemness markers expression was evaluated in clinical samples. Additionally, luciferase reporter assay combined with RNA-Fluorescence in situ hybridization (RNA-FISH) and RNA-binding protein immunoprecipitation (RIP) assays were used to verify the direct binding of miR-873 on PD-L1. Furthermore, flow cytometry, mammosphere formation combined with nude mouse tumor xenograft model were carried out to examine the effects of miR-873/PD-L1 axis on the stemness of breast cancer cells. Finally, MTT assay was performed to determine the effects of miR-873/PD-L1 axis on drug resistance. FINDINGS: PD-L1 expression was positively correlated with the expression of stemness markers, and overexpression of PD-L1 contributed to chemoresistance and stemness-like properties in breast cancer cells via activating PI3K/Akt and ERK1/2 pathways. Mechanistically, miR-873 inhibited PD-L1 expression through directly binding to its 3'-untranslated region (UTR), and miR-873 attenuated the stemness and chemoresistance of breast cancer cells which was dependent on PD-L1 and the downstream PI3K/Akt and ERK1/2 signaling. Notably, the promotion of PD-L1 on the stemness and chemoresistance was enhanced by recombinant PD-1 (rPD-1), this effect was attenuated by PD-1/PD-L1 inhibitor. INTERPRETATION: miR-873/PD-L1 regulatory axis might serve as a therapeutic target to enhance the chemo-sensitivity and eliminate the stemness of breast cancer cells. FUND: This work was supported by the National Nature Science Foundation of China, No. 81702957, China Postdoctoral Science Foundation, No. 2017M620230, the Postdoctoral Research Funding Scheme of Jiangsu Province (2017), No. 1701197B, and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions.

STARD13-correlated ceRNA network-directed inhibition on YAP/TAZ activity suppresses stemness of breast cancer via co-regulating Hippo and Rho-GTPase/F-actin signaling.

BACKGROUND: Targeting cancer stem cells is critical for suppressing cancer progression and recurrence. Finding novel markers or related pathways could help eradicate or diagnose cancer in clinic. METHODS: By constructing STARD13-correlated ceRNA 3'UTR stable overexpression or knockdown breast cancer cells, we aimed to explore the effects of STARD13-correlated ceRNA network on breast cancer stemness in vitro and in vivo. Further RNA-sequencing was used to analyze transcriptome change in combination with functional studies on candidate signaling. Clinical samples obtained from The Cancer Genome Atlas data were used to validate the correlation between STARD13 and related pathways. Finally, in vitro and in vivo experiments were used to examine the effects of STARD13-correlated ceRNA network on chemotherapy sensitivity/resistance. RESULTS: Here, we revealed that this ceRNA network inhibited stemness of breast cancer. Mechanistically, we found that activation of STARD13-correlated ceRNA network was negatively correlated with YAP/TAZ activity in breast cancer. Specifically, this ceRNA network attenuated YAP/TAZ nuclear accumulation and transcriptional activity via collectively modulating Hippo and Rho-GTPase/F-actin signaling. Finally, we demonstrated that YAP/TAZ transcriptional activity regulated by this ceRNA network was involved in chemoresistance. CONCLUSIONS: Our results uncover a novel mechanism of YAP/TAZ activation in breast cancer and propose the possibility to drive STARD13-correlated ceRNA network to inhibit breast cancer stem cell traits.