Telomerase is constitutively overexpressed in the majority of human cancers and telomerase inhibition provides a promising broad-spectrum anticancer therapeutic strategy. BIBR 1532 is a well-known synthetic telomerase inhibitor that blocks the enzymatic activity of hTERT, the catalytic subunit of telomerase. However, water insolubility of BIBR 1532 leads to low cellular uptake and inadequate delivery and thus, limits its anti-tumor effects. Zeolitic imidazolate framework-8 (ZIF-8) is considered as an attractive drug delivery vehicle for improved transport, release and anti-tumor effects of BIBR 1532. Herein, ZIF-8 and BIBR[email protected]were synthesized, respectively, and the physicochemical characterizations confirmed the successful encapsulation of BIBR 1532 in ZIF-8 coupled with an improved stability of BIBR 1532. ZIF-8 could alter the permeability of lysosomal membrane probably by the imidazole ring-dependent protonation. Moreover, ZIF-8 encapsulation facilitated the cellular uptake and release of BIBR 1532 with more accumulation in the nucleus. BIBR 1532 encapsulation with ZIF-8 triggered a more obvious growth inhibition of cancer cells as compared with free BIBR 1532. A more potent inhibition on hTERT mRNA expression, aggravated G0/G1 arrest accompanied with an increased cellular senescence were detected in BIBR[email protected]cancer cells. Our work has provided preliminary information on improving the transport, release and efficacy of water-insoluble small molecule drugs by using ZIF-8 as a delivery vehicle.Keywords:ZIF-8;drug loading;transport;protonation effect;telomerase inhibitor
Lin Liu,Daohong Wu,Shuang Zhen,Kaiqing Lu,Xinyao Yi,Zhifang Sun
This work reports on a simple and sensitive electrochemical strategy for the detection of telomerase extracted from HeLa cells. It was based on the signal amplification of in-situ performed streptavidin-biotin-DNA-biotin (SA-biotin-DNA-biotin) networks. Specifically, the DNA primer immobilized on a gold electrode was elongated by telomerase. After the hybridization of biotin-DNA-biotin to the extended primer, the in-situ formation of SA-biotin-DNA-biotin networks was initiated on the electrode surface within 10 min through the SA-biotin interactions. The resulting networks created an insulating layer, thus hampering the electron transfer and causing the significant increase in the electrochemical impedance. Telomerase extracted from 2 HeLa cells can be readily measured. The method showed a linear relationship in the range of 50 ∼ 5000 cells/mL. The signal-amplified strategy can be applied to develop novel sensing platforms for the detection of different biomarkers.
The accurate evaluation of telomerase activity, a typical cancer biomarker, is vital for early cancer screening. In this study, we developed a dark-field microscopy (DFM) visual single-particle detection scheme to detect telomerase activity based on automatic counting gold nanoparticles (AuNPs). This method started with attaching the telomerase substrate (TS) primer to the magnetic beads (MBs) through streptavidin-biotin interaction. In the presence of telomerase and dNTPs, the TS primer was expanded with (TTAGGG) n repeat units to form the telomerase extension product (MBs-telomerase extension product), which could be hybridized with the complementary DNA (cDNA) modified with AuNPs through Au-S bonds (AuNPs-SH-cDNA). After magnetic separation and DNA double-strand unwinding, AuNPs were collected from the supernatant, and the telomerase activity was quantitatively measured by visually counting bright spots based on DFM. This strategy achieved a limit of detection as low as 1 HeLa cell and distinguished telomerase activity among different cell lines, thus verifying its excellent sensitivity and specificity. Further, two common telomerase inhibitors (BIBR1532 and curcumin) were screened with the consistent IC 50 values with other methods, respectively. It is worth mentioning that this strategy can clearly identify bladder cancer among various urinary diseases. Consequently, the visualized automatic particle counting strategy is potential as a powerful tool in early and noninvasive diagnosis of bladder cancer.
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