Shasha Zhao

On the Mechanism of Plasma Inducing Cell Apoptosis

In recent years, atmospheric pressure nonequilibrium plasmas (APNPs) have been used in many biomedical applications such as bacteria, yeasts, fungi and algae inactivation, surface treatment for cell sheet engineering to controlled cell cultivation, promote blood coagulation and root canal of teeth sterilization. The APNPs can operate at room temperature and APNPs can form numerous short-lived but highly active chemical particles, such as reactive oxygen species, hydroxyl radical (OH), and other excited species. These active chemical particles are essential for various biological processes in cells and human body, reactive oxygen species are involved in initiation, progression and metastasis of cancers and nitric oxide (NO) can induce apoptosis, necrosis or protect cells from death, depending on the cell type and the amount, duration, and site of NO production. Therefore, it is important to study the impact of plasma on cancer cells.

Atmospheric Pressure Room Temperature Plasma Jets Facilitate Oxidative and Nitrative Stress and Lead to Endoplasmic Reticulum Stress Dependent Apoptosis in HepG2 Cells

Atmospheric pressure room temperature plasma jets (APRTP-Js) that can emit a mixture of different active species have recently found entry in various medical applications. Apoptosis is a key event in APRTP-Js-induced cellular toxicity, but the exact biological mechanisms underlying remain elusive. Here, we explored the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in APRTP-Js-induced apoptosis using in vitro model of HepG2 cells. We found that APRTP-Js facilitated the accumulation of ROS and RNS in cells, which resulted in the compromised cellular antioxidant defense system, as evidenced by the inactivation of cellular antioxidants including glutathione (GSH), superoxide dismutase (SOD) and catalase. Nitrotyrosine and protein carbonyl content analysis indicated that APRTP-Js treatment caused nitrative and oxidative injury of cells. Meanwhile, intracellular calcium homeostasis was disturbed along with the alteration in the expressions of GRP78, CHOP and pro-caspase12. These effects accumulated and eventually culminated into the cellular dysfunction and endoplasmic reticulum stress (ER stress)-mediated apoptosis. The apoptosis could be markedly attenuated by N-acetylcysteine (NAC, a free radical scavenger), which confirmed the involvement of oxidative and nitrative stress in the process leading to HepG2 cell apoptosis by APRTP-Js treatment.

Anti-tumor effect of germacrone on human hepatoma cell lines through inducing G2/M cell cycle arrest and promoting apoptosis.

Germacrone is one of the main bioactive components in the traditional Chinese medicine Rhizoma curcuma. In this study, the anti-proliferative effect of germacrone on the human hepatoma cell lines and the molecular mechanism underlying the cytotoxicity of germacrone were investigated. Treatment of human hepatoma cell lines HepG2 and Bel7402 with germacrone resulted in cell cycle arrest and apoptosis in a dose-dependent manner as measured by MTT assay, flow cytometric and fluorescent microscopy analysis, while much lower effect on normal human liver cell L02 was observed. Flow cytometric analysis revealed that germacrone induced G2/M arrest in the cell cycle progression that was associated with an obvious decrease in the protein expression of cyclin B1 and its activating partner CDK1 with concomitant inductions of p21. Hoechst 33258 and Annexin V/PI staining results showed that the total cell number in apoptosis associated with a dose-dependent up-regulation of Bax and down-regulation of Bcl-2/Bcl-xl was increased. In the meantime, the up-regulation of p53 and reactive oxygen species increase were observed, which suggested that germacrone might be a new potent chemopreventive drug candidate for liver cancer via regulating the expression of proteins related to G2/M cell cycle and apoptosis, and p53 and oxidative damage may play important roles in the inhibition of human hepatoma cells growth by germacrone.

Single-cell-precision microplasma-induced cancer cell apoptosis.

The issue of single-cell control has recently attracted enormous interest. However, in spite of the presently achievable intracellular-level physiological probing through bio-photonics, nano-probe-based, and some other techniques, the issue of inducing selective, single-cell-precision apoptosis, without affecting neighbouring cells remains essentially open. Here we resolve this issue and report on the effective single-cell-precision cancer cell treatment using the reactive chemistry of the localized corona-type plasma discharge around a needle-like electrode with the spot size ∼1 µm. When the electrode is positioned with the micrometer precision against a selected cell, a focused and highly-localized micro-plasma discharge induces apoptosis in the selected individual HepG2 and HeLa cancer cells only, without affecting any surrounding cells, even in small cell clusters. This is confirmed by the real-time monitoring of the morphological and structural changes at the cellular and cell nucleus levels after the plasma exposure.

The Interactive Effects of Transgenically Overexpressed 1Ax1 with Various HMW-GS Combinations on Dough Quality by Introgression of Exogenous Subunits into an Elite Chinese Wheat Variety

Seed storage proteins in wheat endosperm, particularly high-molecular-weight glutenin subunits (HMW-GS), are primary determinants of dough properties, and affect both end-use quality and grain utilization of wheat (Triticum aestivum L). In order to investigate the interactive effects between the transgenically overexpressed 1Ax1 subunit with different HMW-GS on dough quality traits, we developed a set of 8 introgression lines (ILs) overexpressing the transgenic HMW-glutenin subunit 1Ax1 by introgression of this transgene from transgenic line B102-1-2/1 into an elite Chinese wheat variety Chuanmai107 (C107), using conventional crossing and backcrossing breeding technique. The donor C107 strain lacks 1Ax1 but contains the HMW-GS pairs 1Dx2+1Dy12 and 1Bx7+1By9. The resultant ILs showed robust and stable expression of 1Ax1 even after five generations of self-pollination, and crossing/backcrossing three times. In addition, overexpression of 1Ax1 was compensated by the endogenous gluten proteins. All ILs exhibited superior agronomic performance when compared to the transgenic parent line, B102-1-2/1. Mixograph results demonstrated that overexpressed 1Ax1 significantly improved dough strength, resistance to extension and over-mixing tolerance, in the targeted wheat cultivar C107. Further, comparisons among the ILs showed the interactive effects of endogenous subunits on dough properties when 1Ax1 was overexpressed: subunit pair 17+18 contributed to increased over-mixing tolerance of the dough; expression of the Glu-D1 allele maintained an appropriate balance between x-type and y-type subunits and thereby improved dough quality. It is consistent with ILs C4 (HMW-GS are 1, 17+18, 2+12) had the highest gluten index and Zeleny sedimentation value. This study demonstrates that wheat quality could be improved by using transgenic wheat overexpressing HMW-GS and the feasibility of using such transgenic lines in wheat quality breeding programs.

Combined Effect of N-Acetylcysteine (NAC) and Plasma on Proliferation of HepG2 Cells

It is found that proliferation of HepG2 cells is promoted in the N-acetylcysteine (NAC) and plasma cotreatment group while the group without NAC undergoes cell apoptosis or cell death after plasma treatment. Further investigation found that NAC and plasma cotreatment accelerates the G1 to S phase transition of HepG2 cells and cyclinD1, which responds for the proliferation, is shown to be significantly up-regulated in the NAC and plasma cotreatment group. This finding provides a rationale for developing a proliferation-promotion approach and sheds new sights on the potential application of cold plasmas such as large-scale culture of stem cells in vitro for stem cell transplantation, enhancing transplanted tissue incorporation.

Fucoidan induces Apoptosis in MDA-MB-231 Cells by Activating Caspase Cascade and Down-regulating XIAP

Amal M. Banafa, Sadia Roshan, Yunyi Liu (柳昀熠), Shasha Zhao(赵沙沙), Guangxiao Yang (杨广笑) , Guangyuan He (何光源) , Mingjie Chen (陈明洁: 通讯作者)# The Genetic Engineering International Cooperation Base of Ministry of Science and Technology, Key Laboratory of Molecular Biophysics of Chinese Ministry of Education, College of Life Science and Technology, Huazhong University of Science & Technology (HUST), Luoyu Road 1037, Wuhan, Hubei, 430074, P.R. China

Cell apoptosis induced by atmospheric pressure plasma

Reports show that atmospheric pressure cold plasma could induce cancer cell apoptosis in several minutes. However, up to now, only little has been known about the mechanism of plasma inducing cancer cell apoptosis. In this paper, an atmospheric pressure plasma plume is used to treat human hepatocellular carcinoma (HepG2) cell. Experimental results show that plasma can modulate the intracellular reactive oxygen species (ROS), and nitric oxide (NO) concentration. The relationship between the cell apoptosis and the concentrations of ROS, and NO is analysis. The results indicate that, firstly, the plasma generates NO, which increase the NO concentration of the cells outer environment. Secondly, the intracellular NO concentration is increased due to the NO diffusion from the medium. Thirdly, the intracellular ROS concentration is increased due to the increase of the intracellular NO concentration. Finally, the increase of the intracellular NO, and ROS concentrations result in the HepG2 cell apoptosis.