Realgar quantum dots induce apoptosis and necrosis in HepG2 cells through endoplasmic reticulum stress

Abstract

Abstract. Realgar (As 4 S 4 ) has been used in traditional Chinese medicines for treatment of malignancies. However, the poor water solubility of realgar limits its clinical application. To overcome this problem, realgar quantum dots (RQDs; 5.48±1.09 nm) were prepared by a photoluminescence method. The mean particle size was characterized by high-resolution transmission electron microscopy and scanning electron microscopy. Our recent studies revealed that the RQDs were effective against tumor growth in tumor-bearing mice without producing apparent toxicity. The present study investigated their anticancer effects and mechanisms in human hepatocellular carcinoma (HepG2) cells. The HepG2 cells and human normal liver (L02) cells were used to determine the cytotoxicity of RQDs. The portion of apoptotic and dead cells were measured by flow cytometry with Annexin V-fluorescein isothiocyanate/propidium iodide double staining. Apoptosis-related proteins and genes were examined by western blot analysis and reverse transcription-quantitative polymerase chain reaction, and the mitochondrial membrane potential was assayed by confocal microscope with JC-1 as a probe. RQDs exhibited cytotoxicity in a concentration-dependent manner and HepG2 cells were more sensitive compared with normal L02 cells. At 15 µg/ml, 20% of the cells were apoptotic, while 60% of the cells were necrotic at 30 µg/ml. The anti-apoptosis protein Bcl-2 was dose-dependently decreased, while pro-apoptotic protein Bax was increased. There was a loss of mitochondrial membrane potential and expression of the stress genes C/EBP-homologous protein 10 and glucose-regulated protein 78 was increased by RQDs. RQDs were effective in the inhibition of HepG2 cell proliferation and this effect was due to induction of apoptosis and necrosis through endoplasmic reticulum stress. IntroductionThe use of arsenic in China can be traced back thousands of years. Arsenic and arsenic salts, including orpiment, realgar and arsenolite, were fundamental ingredients in certain cancer treatments (1). The Fowler's solution (1% potassium arsenite) was used in the treatment of malignant diseases, such as leukemia and Hodgkin's disease, by numerous physicians in the 19-20th centuries (1). Arsenic trioxide (As 2 O 3 ) has emerged as the first-line therapy in the treatment of acute promyelocytic leukemia (APL); however, the toxicity hinders its clinical applications (2,3).Realgar contains >90% arsenic sulfide and is widely used externally and internally in a number of traditional medicine recipes in China (4). For example, realgar in combination with Indigo naturalis and Salvia miltiorrhiza is effective against APL (5), and targets RING-type E3 ligase c-CBL to induce degradation of BCR-Abl in chronic myelogenous leukemia (6). Realgar also enhances the antitumor effects of imatinib (7). Results from multicenter clinical trials using oral realgar formulations plus intravenous As 2 O 3 against hematological malignancy are promising (8).However, realgar is insoluble in water, resulting in poor ...

Caveolin-1 contributes to realgar nanoparticle therapy in human chronic myelogenous leukemia K562 cells

“…30 Recently, several types of realgar NPs have been developed, and more effective results have been achieved compared with crude realgar in antitumor studies. 13,31,32 It has been reported that realgar NP suspension prepared by "solvent relay" strategy induces both apoptosis and necrosis in leukemia cell lines K562 and HL-60. 33 In the present study, realgar NP suspension prepared by using high-energy ball milling was used, as reported in a previous study.…”

Nickel oxide nanoparticles induce hepatocyte apoptosis via activating endoplasmic reticulum stress pathways in rats

“…The cellular response to ER stress is critical for cell survival, and its disruption can lead to apoptosis . Realgar quantum dots (5.48 ± 1.09 nm) can inhibit hepatocyte proliferation, due to ER stress‐mediated apoptosis . GRP78, as a general ER stress marker, binds to URP with its peptide‐binding domain, and possesses an ATPase domain for folding activity .…”

Review of toxicological effect of quantum dots on the liver

“…Unfortunately, it is still unclear what role ER stress plays in the induction of hepatotoxicity by QDs and little research has been reported. The Qin et al study reveals that Realgar QD‐induced ER stress markers GRP78 and CHOP were significantly increased ( P < .05) in HepG2 cells (Qin, Wang, Liu, Liu, & Wu, ). However, it does not get an in‐depth exploration into the role of ER stress‐induced apoptosis in the HepG2 cells by QDs.…”

“…Paesano et al, 2016 Realgar QDs: 5.48 nm HepG2 cells 0-80 μg ml −1 Cell death and MMP decreased in a dose-dependent manner, IC 50 for HepG2 after 6 h was 23 μg ml −1 ;Bcl-2 showed dose-dependent decrease and Bax was increased at the level of gene and protein;ER stress gene GRP78 and CHOP increased by 30-and 10-fold, respectively. Qin et al, 2015 GSH, reduced glutathione; GSSG, oxidised glutathione; MMP, matrix metalloproteinase; PHL, primary human liver (cells); QDs, quantum dots; ROS, reactive oxygen species; SOD, superoxide dismustase; TNF, tumor necrosis factor. , observed 3 h QDs were mainly deposited in the liver sinusoids and selectively taken up by sinusoidal cells (Kupffer cells and liver sinusoidal endothelial cells) instead of by hepatocytes within 3 h. Liang et al, 2015 CdSe QDs: 4 nm Male Kunming mice Intraperitoneal injection 20 and 200 nm for 48 h, 5 and 10 nm for 6 weeks, observed 48 h and 6 weeks QDs were mainly deposited in the liver via both the acute and chronic exposure; QDs caused morphological alternation to the hepatic lobules and increased oxidative stress.…”