LZ-106, a potent lysosomotropic agent, causing TFEB-dependent cytoplasmic vacuolization.

Cytoplasmic vacuolization usually occurs in cells treated with different agents and substances. We found that LZ-106, an analog of enoxacin, is a potent lysosomotropic agent, contributing to the formation of cytoplasmic vacuoles in cells. Studies of LZ-106-induced vacuolization in H460 cells showed acid environment inside these vacuoles. Further study demonstrated that markers in the late endosomes and lysosomes, like LAMP1 and RAB7, on the surface of the vacuoles, implying that these vacuoles might derive from endosomes and/or lysosomes. By studying the fluorescence intensity of LZ-106, we discovered that LZ-106 tended to locate in acid organelles, and Bafilomycin A1, a V-ATPase inhibitor, was able to suppress its acid organelles localization. Also, we noticed that LZ-106 could induce lysosome stress, involving pH increment and lysosomal membrane damage. Moreover, the expression levels of some lysosome-related proteins, like LAMP1, EEA1, and Cathepsin B, were also altered upon LZ-106 treatment. At last, we confirmed LZ-106 can activate TFEB, a key regulator of lysosomes. Knockdown of TFEB could also reverse LZ-106's effect on vacuolization in H460 cells. Taken together, due to LZ-106's lysosomotropic properties, it is able to accumulate in the acid organelles and induce lysosomal dysfunction in H460 cells, leading to TFEB activation and the following cytoplasmic vacuolization.

G1 phase cell cycle arrest in NSCLC in response to LZ-106, an analog of enoxacin, is orchestrated through ROS overproduction in a P53-dependent manner.

LZ-106, a newly synthetized analog of quinolone, has been shown to be highly effective in non-small cell lung cancer (NSCLC) in both cultured cells and xenograft mouse model with low toxicity, yet the molecular mechanisms still require exploration. Here, we substantiated the involvement of P53 activation in intracellular reactive oxygen species (ROS) generation upon LZ-106 treatment and related P53 to the ROS-induced viability inhibition and apoptosis, which was exhibited in the previous research. P53 was shown to play an indispensable role in the elevated levels of intracellular ROS in LZ-106-treated NSCLC cells through ROS detection. We further identified the anti-proliferation effect of LZ-106 in NSCLC cells through G1 phase cell cycle arrest by cell cycle analysis, with the expression analysis of the key proteins, and discovered that the cell cycle arrest effect is also mediated by induction of ROS in a P53-dependent manner. In addition, the tumor suppression effect exhibited in vivo was demonstrated to be similar to that in vitro, which requires the participation of P53. Thus, LZ-106 is a potent antitumor drug possessing potent proliferation inhibition and apoptosis induction ability through the P53-dependent ROS modulation both in vitro and in vivo.

Enoxacin and bis-enoxacin stimulate 4T1 murine breast cancer cells to release extracellular vesicles that inhibit osteoclastogenesis.

Enoxacin and its bone-seeking bisphosphonate derivative, bis-enoxacin, have recently captured attention as potential therapeutic agents for the treatment of cancer and bone disease. No differences in growth or survival of 4T1 murine breast cancer cells were detected at a concentration of 50 µM of enoxacin or bis-enoxacin. Growth was perturbed at higher concentrations. Both 50 µM enoxacin and bis-enoxacin stimulated increases in the number of GW/Processing bodies, but there were minimal changes in microRNA levels. Extracellular vesicles (EVs) released from 4T1 cells treated with 50 µM enoxacin or 50 µM bis-enoxacin stimulated proliferation of RAW 264.7 cells, and both significantly inhibited osteoclastogenesis in calcitriol-stimulated mouse marrow. EVs from 4T1 cells treated with enoxacin and bis-enoxacin displayed small reductions in the amount of microRNA (miR)-146a-5p and let-7b-5p. In marked contrast, miR-214-3p, which has been shown to regulate bone remodeling, was increased 22-fold and 30-fold respectively. We conclude that enoxacin and bis-enoxacin trigger the release of EVs from 4T1 cancer cells that inhibit osteoclastogenesis.

LZ-106, a novel analog of enoxacin, inducing apoptosis via activation of ROS-dependent DNA damage response in NSCLCs.

Lung cancer, especially non-small-cell lung cancer (NSCLC), plays the leading role in cancer which is closely related to a myriad of fatal results. Unfortunately, current molecular mechanisms and clinical treatment of NSCLC still remain to be explored despite the fact that intensive investigations have been carried out in the last two decades. Recently, growing attention to finding exploitable sources of anticancer agents is refocused on quinolone compounds, an antibiotic with a long period of clinic application, for their remarkable cell-killing activity against not only bacteria, but eukaryotes as well. In this study, we found LZ-106, an analog of enoxacin, exhibiting potent inhibitory effects on NSCLC in both cultured cells and xenograft mouse model. We identified apoptosis-inducing action of LZ-106 in NSCLC cells through the mitochondrial and endoplasmic reticulum (ER)-stress apoptotic pathways via Annexin-V/PI double-staining assay, membrane potential detection, calcium level detection and the expression analysis of the key apoptotic proteins. Through comet assay, reactive oxygen species (ROS) detection, the expression analysis of DNA damage response (DDR) marker γ-H2AX and other DDR-related proteins, we also demonstrated that LZ-106 notably induced ROS overproduction and DDR. Interestingly, additional evidence in our findings revealed that DDR and apoptosis could be alleviated in the presence of ROS scavenger N-acetyl-cysteine (NAC), indicating ROS-dependent DDR involvement in LZ-106-induced apoptosis. Thus our data not only offered a new therapeutic candidate for NSCLC, but also put new insights into the pharmacological research of quinolones.

Reversed-phase high-performance liquid chromatographic determination of enoxacin and 4-oxo-enoxacin in human plasma and prostatic tissue. Application to a pharmacokinetic study.

A simple high-performance liquid chromatographic method has been developed for the simultaneous determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue. The work-up procedure involves a liquid-liquid extraction step followed by isocratic chromatography on a reversed-phase analytical column, with ultraviolet absorbance detection (lambda = 340 nm). Using a mobile phase of 20.9% (v/v) acetonitrile buffer (pH 2.1), adequate retention time and separation among the analytes has been obtained using tetrabutylammonium hydroxide included in the eluent. Retention times are 5.2 min for enoxacin, 6.8 min for pefloxacin and 12 min for 4-oxo-enoxacin. For plasma and prostatic tissue, the precision of the assay was below 9%. The percent recovery from the nominal values for accuracy ranged from 94 to 108%. The limits of quantitation were 20 ng/ml for plasma and 50 ng/g for tissue (precision < 18%). The detection limits were 10 ng/ml and 25 ng/g, respectively. The calibration curves were linear from 20 to 1000 ng/ml for plasma and from 50 to 2500 ng/g for tissue. In plasma, the extraction recoveries averaged 52% for enoxacin and 63% for 4-oxo-enoxacin. In prostatic tissue, they were 57 and 76% for the two analytes, respectively. This method has been employed for the determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue samples from patients following repeated oral administration of enoxacin (400 mg twice a day for four days).