Enhancing the Release Efficiency of a Molecular Chemotherapeutic Prodrug by Photodynamic Therapy.

Tumor-specific, hypoxia-activated prodrugs have been developed to alleviate the side effects of chemotherapy drugs. However, the release efficiency of hypoxia-activated prodrugs is restricted by the degree of tumor hypoxia, which further leads to poor cancer treatment effects. On the other hand, oxygen is consumed gradually in photodynamic therapy (PDT), which aggravates hypoxia at the tumor site. In this study, we combined hypoxia-activated prodrugs with PDT agents to promote the prodrugs release, thereby improving their bioavailability and therapeutic effects. As a proof of concept, a mitochondria-targeted molecular prodrug, CS-P, was designed and synthesized. It can be selectively activated by tumor hypoxia to release chemotherapeutic drugs and photosensitizers, and then further discharge drugs after light irradiation. The design strategy proposed in this paper provides a new idea for enhancing hypoxia-activated prodrug release and real-time monitoring prodrug release.

A highly sensitive fluorescent probe for HClO and its application in live cell imaging.

A new rhodamine-based probe 1 was designed and synthesized as a new fluorescent molecular probe for HClO in PBS buffer at physiological condition. The free probe 1 almost nonfluorescence, however, a drastic enhancement of fluorescence intensity was observed in the presence of HClO. The new probe 1 exhibits good sensitivity and selectivity for HClO over other reactive oxygen and/or nitrogen species in PBS buffer, and the probe was successfully applied to image endogeneous HClO in the living cells.

A highly selective fluorescent probe for detection of biological samples thiol and its application in living cells.

Probe 1 was designed and synthesized as a new fluorescent molecular probe for thiols in PBS buffer at physiological condition. This fluorescent molecular probe consists of a thiol reaction moiety bound to a coumarin fluorophore. Its fluorescence quantum yield is low, but a drastic enhancement of fluorescence intensity was observed in the presence of thiols. Possible interference with other analytes was examined. Probe 1 displays a highly selective fluorescent enhancement with thiols, and the probe was successfully applied to thiols determination in intracellular, in human urine and blood samples.

FRET-based mitochondria-targetable dual-excitation ratiometric fluorescent probe for monitoring hydrogen sulfide in living cells.

Hydrogen sulfide (H2S) is connected with various physiological and pathological functions. However, understanding the important functions of H2S remains challenging, in part because of the lack of tools for detecting endogenous H2S. Herein, compounds Ratio-H2S 1/2 are the first FRET-based mitochondrial-targetable dual-excitation ratiometric fluorescent probes for H2S on the basis of H2S-promoted thiolysis of dinitrophenyl ether. With the enhancement of H2S concentration, the excitation peak at λ≈402 nm of the phenolate form of the hydroxycoumarin unit drastically increases, whereas the excitation band centered at λ≈570 nm from rhodamine stays constant and can serve as a reference signal. Thus, the ratios of fluorescence intensities at λ=402 and 570 nm (I402/I570) exhibit a drastic change from 0.048 in the absence of H2S to 0.36 in the presence of 180 µM H2S; this is a 7.5-fold variation in the excitation ratios. The favorable properties of the probe include the donor and acceptor excitation bands, which exhibit large excitation separations (up to 168 nm separation) and comparable excitation intensities, high sensitivity and selectivity, and function well at physiological pH. In addition, it is demonstrated that the probe can localize in the mitochondria and determine H2S in living cells. It is expected that this strategy will lead to the development of a wide range of mitochondria-targetable dual-excitation ratiometric probes for other analytes with outstanding spectral features, including large separations between the excitation wavelengths and comparable excitation intensities.

NF-kappaB p65 modulates the telomerase reverse transcriptase in the HepG2 hepatoma cell line.

Nuclear factor-kappa B (NF-kappaB) regulates the expression of various genes, several genes involved in inflammation and tumorigenesis, including those of the liver. A role for NF-kappaB has been implicated in the pathogenesis of hepatocellular carcinoma. This transcription factor can regulate hTERT gene transcription. Expression of hTERT was found to be at high levels in hepatocellular carcinoma. However, positive effects of NF-kappaB on hTERT protein synthesis in HepG(2) cells are unknown. In this study, we show that LPS (specific binding to TLR4 to activate NF-kappaB) was positive for NF-kappaB p65 mRNA expression and activation, and also up-regulated hTERT mRNA and protein expressions at 36h in a dose-dependent manner. In contrast, MG-132 (blocking the activity of 26S proteasome and thereby preventing nuclear translocation of NF-kappaB) significantly inhibited activation of NF-kappaB and mRNA expression. And also reduced the expression of hTERT at both mRNA and protein levels at 36h in a dose-dependent manner. Furthermore, dexamethasone inhibited LPS-induced activation of NF-kappaB and expression of the hTERT in HepG(2) cells. These findings suggest that NF-kappaB may modulate hTERT mRNA level, importantly, in protein level in HepG(2) cells and dexamethasone inhibits LPS-induced hTERT via blocking NF-kappaB.