Cascaded Electrochemiluminescence Signal Amplifier for the Detection of Telomerase Activity from Tumor Cells and Tissues

A target-triggered fluorescence-SERS dual-signal nano-system for real-time imaging of intracellular telomerase activity

Telomerase (TE) is a promising diagnostic and prognostic biomarker for many cancers. Quantification of TE activity in living cells is of great significance in biomedical and clinical research. Conventional fluorescence-based sensors for quantification of intracellular TE may suffer from problems of fast photobleaching and auto-fluorescence of some endogenous molecules, and hence are liable to produce false negative or positive results. To address this issue, a fluorescence-SERS dual-signal nano-system for real-time imaging of intracellular TE was designed by functionalizing a bimetallic Au@Ag nanostructure with 4-p-mercaptobenzoic acid (internal standard SERS tag) and a DNA hybrid complex consisted of a telomerase primer strand and its partially complimentary strand modified with Rhodamine 6G. The bimetallic Au@Ag nanostructure serves as an excellent SERS-enhancing and fluorescence-quenching substrate. Intracellular TE will trigger the extension of the primer strand and cause the shedding of Rhodamine 6G-modified complimentary strand from the nano-system through intramolecular DNA strand displacement, resulting in the recovery of the fluorescence of Rhodamine 6G and decrease in its SERS signal. Both the fluorescence of R6G and the ratio between the SERS signals of 4-p-mercaptobenzoic acid and Rhodamine 6G can be used for in situ imaging of intracellular TE. Experimental results showed that the proposed nano-system was featured with low background, excellent cell internalization efficiency, good biocompatibility, high sensitivity, good selectivity, and robustness to false positive results. It can be used to distinguish cancer cells from normal ones, identify different types of cancer cells, as well as perform absolute quantification of intracellular TE, which endows it with great potential in clinical diagnosis, target therapy and prognosis of cancer patients.

Recent advances in optical biosensing and imaging of telomerase activity and relevant signal amplification strategies

Telomerase as a new valuable biomarker for early diagnosis and prognosis evaluation of cancer has attracted much interest in the field of biosensors, cell imaging, and drug screening. In this review, we mainly focus on different optical techniques and various signal amplification strategies for telomerase activity determination. Fluorometric, colorimetry, chemiluminescence, surface-enhanced Raman scattering (SERS), and dual-mode techniques for telomerase sensing and imaging are summarized. Signal amplification strategies include two categories: one is nucleic acid-based amplification, such as rolling circle amplification (RCA), the hybridization chain reaction (HCR), and catalytic hairpin assembly (CHA); the other is nanomaterial-assisted amplification, including metal nanoclusters, quantum dots, transition metal compounds, graphene oxide, and DNA nanomaterials. Challenges and prospects are also discussed to provide new insights for future development of multifunctional strategies and techniques for in situ and in vivo analysis of biomarkers for accurate cancer diagnosis.

BIBR1532 inhibits proliferation and enhances apoptosis in multiple myeloma cells by reducing telomerase activity

Background

Multiple myeloma (MM) is a rare haematological disorder with few therapeutic options. BIBR1532, a telomerase inhibitor, is widely used in cancer treatment and has promising outcomes. In this study, we investigated the efficacy and mechanism of action of BIBR1532 in MM.

Methods

K562 and MEG-01 cells were cultured with BIBR1532 at different concentrations. After 24 and 48 h, cell survival was analyzed. Next, these cells were cultured with 25 and 50 µM BIBR1532 for 48 h, then, cell proliferation, apoptosis, and the expression of the telomerase activity related markers were tested by 5-Ethynyl-2'-deoxyuridine (EdU) staining, flow cytometric analysis, western blot and quantitative real-time PCR (qRT-PCR), respectively. Expression of Bcl-xL, Bad, Survivin, phosphorylation of PI3K, AKT, mTOR, ERK1/2, and MAPK were tested via western blotting. Further experiments were conducted to evaluate the synergistic effects of BIBR1532 and doxorubicin (Dox) or bortezomib (Bor).

Results

BIBR1532 inhibited K562 and MEG-01 cell survival in a dose- and time-dependent manner. In addition, BIBR1532 hindered cell proliferation while promoting apoptosis, and this effect was enhanced by increasing the BIBR1532 concentration. Moreover, BIBR1532 inhibited TERT and c-MYC expression, PI3K, AKT, mTOR phosphorylation, and facilitated ERK1/2 and MAPK phosphorylation. Additionally, BIBR1532 combined with Dox or Bor showed synergistic effects in MM treatment.

Conclusion

BIBR1532 inhibits proliferation and promotes apoptosis in MM cells by inhibiting telomerase activity. Additionally, BIBR1532 combined with Dox or Bor exhibited synergistic effects, indicating that BIBR1532 may be a novel medicine for the treatment of MM.

Trace Analysis of Emerging Virus: An Ultrasensitive ECL-Scan Imaging System for Viral Infectious Disease

Emerging infectious diseases have brought a huge impact on human society in recent years. The outbreak of Zika virus (ZIKV) in the Americas resulted in a large number of babies born with microcephaly. More seriously, the Coronavirus Disease 2019 (COVID-19) was globally spread and caused immeasurable damages. Thus, the monitoring of highly pathogenic viruses is important to prevent and control emerging infectious diseases. Herein, a dendritic polymer probe-amplified ECL-scan imaging system was constructed to realize trace analysis of viral emerging infectious diseases. A dendritic polymer probe was employed as the efficient signal emitter component that could generate an amplified ECL signal on the integrated chip, and the signal was detected by a single-photon level charge coupled device-based ECL-scan imaging system. With this strategy, the ZIKV in a complex system of blood, urine, and saliva was detected. The results indicated that a high sensitivity of 50 copies and superior specificity were achieved. Furthermore, this strategy realized highly sensitive detection (10 copies) of the S and N protein gene sequence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-Cov2) and spiked pseudovirus samples. Thus, the dendritic polymer probe-amplified ECL-scan imaging system suitably met the strict clinical requirements for trace analysis of an emerging virus, and thus has the potential to serve as a paradigm for monitoring emerging infectious diseases.

Recent advances of functional nucleic acids-based electrochemiluminescent sensing

Electroluminescence (ECL) has been used in extensive applications ranging from bioanalysis to clinical diagnosis owing to its simple device requirement, low background, high sensitivity, and wide dynamic range. Nucleic acid is a significant theme in ECL bioanalysis. The inherent versatile selective molecular recognition of nucleic acids and their programmable self-assembly make it desirable for the robust construction of nanostructures. Benefiting from their unique structures and physiochemical properties, ECL biosensing based on nucleic acids has experienced rapid growth. This review focuses on recent applications of nucleic acids in ECL sensing systems, particularly concerning the employment of nucleic acids as molecular recognition elements, signal amplification units, and sensing interface schemes. In the end, an outlook of nucleic acid-based ECL biosensing will be provided for future developments and directions. We envision that nucleic acids, which act as an essential component for both bioanalysis and clinical diagnosis, will provide a new thinking model and driving force for developing next-generation sensing systems.

Quantitative Detection and Imaging of Multiple Biological Molecules in Living Cells for Cell Screening

Because of insufficient information, a single biomarker is not sufficient for early diagnosis of cancer, whereas sensitive and selective detection of multiple biomolecules can significantly reduce analysis time, sample size, and accurately perform cell screening in early cancer. Therefore, the development of a noninvasive strategy that can simultaneously quantify multiple biomarkers (i.e., nucleic acids, proteins, and small molecules) in a single cell is particularly important. Herein, a universal sensing system (functional DNA@mesoporous silica nanoparticles (MSN)-Black Hole Quencher-rhodamine 6G (RhB), FDSBR), which is based on the combination of functionalized DNA and smart responsive nanomaterial, was successfully constructed. After incubation with the cells, different types of targets trigger the strand displacement reaction to release the fluorophore-labeled nucleic acids as the output signals to reflect the intracellular level of the telomerase and adenosine triphosphate (ATP), respectively. Simultaneously, intracellular miR-21 can be clearly indicated by the restored fluorescence of RhB when the caged double-stranded DNA was substituted into single-stranded DNA to open the pore. The concentrations of intracellular telomerase, miR-21, and ATP were identified successfully in three cell lines at the single-cell level. The results show that the contents of three biomolecules have significant differences in the three model cell lines and provide a promising route for developing innovative early disease diagnosis and cell screening assay.