STAT3/LINC00671 axis regulates papillary thyroid tumor growth and metastasis via LDHA-mediated glycolysis

Lactate dehydrogenase A (LDHA), a critical component of the glycolytic pathway, relates to the development of various cancers, including thyroid cancer. However, the regulatory mechanism of LDHA inhibition and the physiological significance of the LDHA inhibitors in papillary thyroid cancer (PTC) are unknown. Long non-coding RNA (lncRNA) plays a vital role in tumor growth and progression. Here, we identified a novel lncRNA LINC00671 negatively correlated with LDHA, downregulating LDHA expression and predicting good clinical outcome in thyroid cancer. Moreover, hypoxia inhibits LINC00671 expression and activates LDHA expression largely through transcriptional factor STAT3. STAT3/LINC00671/LDHA axis regulates thyroid cancer glycolysis, growth, and lung metastasis both in vitro and in vivo. In thyroid cancer patients, LINC00671 expression is negatively correlated with LDHA and STAT3 expression. Our work established STAT3/LINC00671/LDHA as a critical axis to regulate PTC growth and progression. Inhibition of LDHA or STAT3 or supplement of LINC00671 could be potential therapeutic strategies in thyroid cancer.

Biomimetic Molecular Clamp Nanopores for Simultaneous Quantifications of NAD+ and NADH

NADH/NAD⁺ is pivotal to fundamental biochemistry research and molecular diagnosis, but recognition and detection for them are a big challenge at the single-molecule level. Inspired by the biological system, here, we designed and synthesized a biomimetic NAD⁺/NADH molecular clamp (MC), octakis-(6-amino-6-deoxy)-γ-cyclomaltooctaose, and harbored in the engineered α-HL(M113R)₇ nanopore, forming a novel single-molecule biosensor. The single-molecule measurement possesses high selectivity and a high signal-to-noise ratio, allowing to simultaneously recognize and detect for sensing NADH/NAD⁺ and their transformations.

Crowding-Induced DNA Translocation through a Protein Nanopore

A crowded cellular environment is highly associated with many significant biological processes. However, the effect of molecular crowding on the translocation behavior of DNA through a pore has not been explored. Here, we use nanopore single-molecule analytical technique to quantify the thermodynamics and kinetics of DNA transport under heterogeneous cosolute PEGs. The results demonstrate that the frequency of the translocation event exhibits a nonmonotonic dependence on the crowding agent size, while both the event frequency and translocation time increase monotonically with increasing crowder concentration. In the presence of PEGs, the rate of DNA capture into the nanopore elevates 118.27-fold, and at the same time the translocation velocity decreases from 20 to 120 μs/base. Interestingly, the impact of PEG 4k on the DNA-nanopore interaction is the most notable, with up to ΔΔG = 16.27 kJ mol^-1 change in free energy and 764.50-fold increase in the binding constant at concentration of 40% (w/v). The molecular crowding effect will has broad applications in nanopore biosensing and nanopore DNA sequencing in which the strategy to capture analyte and to control the transport is urgently required.

Nanopore biphasic-pulse biosensor

Nanopores as artificial biomimetic nanodevices are of great importance for their applications in biosensing, nanomedicine and bioelectronics. However, it remains a challenge to detect small biomolecules especially small-sized proteins with high sensitivity and selectivity. In the article, we report a simple and efficient method for small-sized protein detection by constructing biphasic-pulse nanopore biosensor. Unlike the traditional resistive pulse sensing, the biphasic-pulse event can provide unique and abundant fingerprint information. Although the nanopore biphasic-pulse electrical signal is originated from both the molecular exclusion electrical resistance and the surface-charged effect of confined molecule, its frequency and amplitude of the waveform can be adjusted by pH, applied potential and salt concentration. Based on the frequency of the biphasic pulse, nanomolar concentration of proteins could be specifically detected and the limit of detection is 1.2 nM. In addition, the biphasic-pulse nanopore shows well discrimination in similar-sized protein detection and its signal generation is highly reproducible. The nanopore biphasic-pulse biosensor should have broad applications as a new generation of powerful single-molecule device.

Simultaneous High-Resolution Detection of Bioenergetic Molecules using Biomimetic-Receptor Nanopore

A novel artificial receptor, heptakis-[6-deoxy-6-(2-hydroxy-3-trimethylammonion-propyl) amino]-beta-cyclomaltoheptaose, with similar functions of mitochondrial ADP/ATP carrier protein, was synthesized and harbored in the engineered α-HL (M113R)₇ nanopore, forming a single-molecule biosensor for sensing bioenergetic molecules and their transformations. The strategy significantly elevates both selectivity and signal-to-noise, which enables simultaneous recognition and detection of ATP, ADP, and AMP by real-time single-molecule measurement.

Target-controlled liposome amplification for versatile nanopore analysis

We have reported a versatile nanopore method based on the combination of analyte-controlled liposome signal amplification and the nanopore detection of a reporter molecule, which largely extends the nanopore application range, and easily elevates the nanopore sensitivity to the fM level from the μM level.

Single-molecule porphyrin-metal ion interaction and sensing application

It remains a significant challenge to study the interactions between metal ions and porphyrin molecules at single ion level. Here, we constructed a nanopore-based sensing for label-free and real-time analysis of the interaction between Cu²⁺ and 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TPPS). The results demonstrate that emerging electronic signatures of the Cu²⁺-TPPS complex that is completely different form the original free TPPS were observed in the α-hemolysin (α-HL) nanopore. Based on the distinctive electronic signal patterns between TPPS and Cu²⁺-TPPS complex, the unique nanopore sensor can achieve a highly sensitive detection of Cu²⁺ in aqueous media. The frequency of signature events showed a linear response toward the concentration of Cu²⁺ in the range of 0.03 µM - 1.0 μM, with a detection limit of 16 nM (S/N = 3). The sensing system also exhibited high selectivity against other metal ions, and the feasibility of this approach for practical applications was demonstrated with the determination of Cu²⁺ in running water.

Fast and precise detection of DNA methylation with tetramethylammonium-filled nanopore

The tremendous demand for detecting methylated DNA has stimulated intensive studies on developing fast single-molecule techniques with excellent sensitivity, reliability, and selectivity. However, most of these methods cannot directly detect DNA methylation at single-molecule level, which need either special recognizing elements or chemical modification of DNA. Here, we report a tetramethylammonium-based nanopore (termed TMA-NP) sensor that can quickly and accurately detect locus-specific DNA methylation, without bisulfite conversion, chemical modification or enzyme amplification. In the TMA-NP sensor, TMA-Cl is utilized as a nanopore-filling electrolyte to record the ion current change in a single nanopore triggered by methylated DNA translocation through the pore. Because of its methyl-philic nature, TMA can insert into the methylcytosine-guanine (mC-G) bond and then effectively unfasten and reduce the mC-G strength by 2.24 times. Simultaneously, TMA can increase the stability of A-T to the same level as C-G. The abilities of TMA (removing the base pair composition dependence of DNA strands, yet highly sensing for methylated base sites) endow the TMA-NP sensor with high selectivity and high precision. Using nanopore to detect dsDNA stability, the methylated and unmethylated bases are easily distinguished. This simple single-molecule technique should be applicable to the rapid analysis in epigenetic research.

Stochastic detection of enantiomers

The rapid quantification of the enantiomers of small chiral molecules is very important, notably in pharmacology. Here, we show that the enantiomers of drug molecules can be distinguished by stochastic sensing, a single-molecule detection technique. The sensing element is an engineered alpha-hemolysin protein pore, fitted with a beta-cyclodextrin adapter. By using the approach, the enantiomeric composition of samples of ibuprofen and thalidomide can be determined in less than 1 s.