Xiaoxi Zeng

Role of p53 and p21 polymorphisms in the risk of cervical cancer among Chinese women

The objective of this study was to identify whether polymorphic variants of p53 at codon 72 and p21 at codon 31 were associated with increased risk for cervical cancer, either independently or jointly, among Chinese women from southern Han. We genotyped p53 codon 72 and p21 codon 31 polymorphisms of peripheral blood DNA from 104 cervical cancer patients and 160 controls. Genotyping was confirmed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct DNA sequencing. We observed an increased risk of cervical cancer associated with the p53 Arg/Arg (OR, 2.25; 95% CI, 1.11-4.54) or p21 Ser/Ser (OR, 2.09; 95% CI, 1.04-4.19) genotype, compared with the p53 Pro/Pro or p21 Arg/Arg genotype, respectively. In additional, interaction between these p53 and p21 polymorphisms increased the risk of cervical cancer in a multiplicative manner, with the OR being 3.96 (95% CI, 1.51-10.41) for subjects carrying both p53 Arg/Arg and p21 Ser/Ser genotypes. These findings suggest that there is a significant association between the genetic polymorphism of p53, p21, and the risk of cervical cancer among Chinese southern women, and there is a possible gene-gene interaction in the incidence of cervical cancer.

Association of TP53 codon 72 polymorphism with cervical cancer risk in Chinese women

Polymorphism at codon 72 of TP53, resulting in either the arginine (Arg) or proline (Pro) form of p53 (R72P), has been associated with the susceptibility to different cancers. To better understand the role of this polymorphism in cervical cancer etiology, we investigated the association between p53 R72P and cervical cancer risk in Chinese women from southern Han. Blood samples from 105 women with cervical cancer and from 140 female blood donors were collected. DNA from peripheral blood lymphocytes was extracted, and the exon 4 of TP53 was amplified by polymerase chain reaction and then digested by BstUI. We observed that the Arg/Arg genotype was significantly associated with an increased risk for cervical cancer [odds ratio (OR)=1.465, 95% confidence interval (95%CI)=1.04-2.138, P=0.02]. The relative frequency of each allele was 0.69 for Arg and 0.31 for Pro in patients with cervical cancer, and 0.60 for Arg and 0.40 for Pro in normal controls (P<0.05). Furthermore, we also found that the TP53 R72P polymorphism was not linked to tumor histologic type, histologic grade, lymph node metastases, and tumor size. These findings suggest that the TP53 codon 72 polymorphism may be implicated in cervical carcinogenesis, with the Arg/Arg genotype being associated with an increased susceptibility for this malignancy in the southern Chinese population.

Optimization for extracellular biosynthesis of silver nanoparticles by Penicillium aculeatum Su1 and their antimicrobial activity and cytotoxic effect compared with silver ions

The present study addresses an eco-friendly and energy-saving method for extracellular biosynthesis of silver nanoparticles (AgNPs) using a cell free filtrate of the fungus strain Penicillium aculeatum Su1 as a reducing agent. Parametric optimization of the biosynthesis process demonstrated different effects on the size, distribution, yield, and synthesis rate of biosynthesized AgNPs. The transmission electron microscopy (TEM) measurements demonstrated that AgNPs were spherical or approximately spherical, with a size between 4 and 55nm. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses indicated that AgNPs were nanocrystalline by nature, with the character of a face-centered cubic (fcc). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the existence of protein molecules that acted as a reducing agent and a capping agent during the biosynthesis process. Furthermore, the biosynthesized AgNPs exhibited higher antimicrobial activity than silver ions against Gram negative bacteria, Gram positive bacteria and fungi. Compared with silver ions, the biosynthesized AgNPs presented higher biocompatibility toward human bronchial epithelial (HBE) cells and high cytotoxicity in a dose-dependent manner with an IC50 of 48.73μg/mL toward A549 cells. These results demonstrate that Penicillium aculeatum Su1 is a potential bioresource that can be used to produce low-cost and eco-friendly AgNPs as efficient antimicrobial agent, drug delivery vehicle or anticancer drug for clinic treatment.

Association of Methylation of the RAR-β Gene with Cigarette Smoking in Non-Small Cell Lung Cancer with Southern-central Chinese Population

Pathogenesis of lung cancer is a complicated biological process including multiple genetic and epigenetic changes. Since cigarette smoking is confirmed as the most main risk factor of non-small cell lung cancer (NSCLC), the aim of this study was to determine whether tobacco exposure plays a role in gene methylation. Methylation of the RAR-β gene were detected using methylation-specific polymerase chain reaction in DNA from 167 newly diagnosed cases with NSCLC and corresponding 105 controls. A significant statistical association was found in the detection rate of the promoter methylation of RAR-β gene between NSCLC and controls (x2=166.01; p<0.01), and hypermethylation of the RAR-β gene was significantly associated with smoking status (p=0.038, p<0.05). No relationship was found between RAR-β gene methylation and pathologic staging including clinical stage, cell type, gender and drinking (p>0.05), and the methylation of RAR-β gene rate of NSCLC was slightly higher in stages III+IV (80.0%) than in I+II (70.8%). Similar results were obtained for methylation of the RAR-β gene between squamous cell carcinoma (77.9%) and other cell type lung cancer (73.9%). These results showed that the frequency of methylation increased gradually with the development of clinical stage in smoking-associated lung cancer patients, and tobacco smoke may be play a potential role in RAR-β gene methylation in the early pathogenesis and process in lung cancer, particularly squamous cell carcinoma. Aberrant promoter methylation is considered to be a promising marker of previous carcinogen exposure and cancer risk.

MDM2 Gene Promoter Polymorphism and Risk of Cervical Cancer in Chinese Population

Purpose: Mouse double minute 2 (MDM2) is a key negative regulator of the p53 activity. Recently, a polymorphism in the intronic promoter, SNP309, was shown to influence MDM2 expression and p53 activity. We examined whether the SNP309 was related to the risk of developing cervical cancer among Chinese populations. Experimental Design: We genotyped the MDM2 polymorphism SNP309 of peripheral blood DNA from 110 cervical cancer patients and from 160 controls. Genotyping were confirmed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct DNA sequencing. The logistic regression analysis was used to calculate adjusted odds ratio (OR) and 95% confidence interval (95%CI). Results: We observed that compared with the TT genotype, the GG genotype was associated with significant increased susceptibility to cervical cancer (OR =2.69, 95% CI =1.26-5.71, P=0.008). The relative frequency of each allele was 0.623 for G and 0.377 for T in patients with cervical cancer, and 0.50 for G and 0.50 for T in normal controls (P<0.05). Furthermore, we also found that the MDM2 SNP309 GG genotype was significantly associated with lymph node metastasis but not tumor histological type, tumor grade and size. Conclusions: Our findings show a significant association between functional polymorphism in MDM2 and increased risk of developing cervical cancer in Chinese population. In addition, the SNP309 GG genotype may be a risk factor for lymph node metastasis of cervical cancer.

Isolation, genetic identification and degradation characteristics of COD-degrading bacterial strain in slaughter wastewater

Contamination of water by meat production is an important and extensive environmental problem and even threat to human health. Biodegradation is a major mechanism which removes the pollutants from the environment. Therefore, the present study aimed to isolate and characterize a COD degrading bacteria which can effectively degrade slaughter wastewater. Six COD degrading bacteria were isolated from slaughtering waste water and sludge in Hunan a meat product Co., Ltd. And the COD degradation rate of each strain was determined by potassium permanganate method. Through observing morphologically and analyzing sequence to 16S rDNA, the highest COD degradation strain was Bacillus velezensis by preliminarily identified and classified, reaching 11.80%. The suitable conditions of the growth of Bacillus velezensis strain were 37 °C, pH 7.0, the peptone concentration 1.5%, and the yeast extract concentration 0.8%.

Extracellular Biosynthesis, Characterization and Cytotoxic Effect of Silver Nanoparticles by Streptomyces coelicoflavus KS-3

The present work aimed to investigate extracellular biosynthesis of silver nanoparticles (AgNPs) mediated by an actinomycete strain and their cytotoxic effects compared with silver ions. The selected strain was identified as Streptomyces coelicoflavus KS-3 by phenotypical characteristics and 16S rRNA analysis. The formation of biosynthesized AgNPs was proved by an absorption peak observed at 437 nm. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses revealed that the prepared AgNPs were spherical or approximately spherical followed by a small amount of truncated triangular, quadrangular and hexagonal with the particle diameters ranging from 2.33 to 91.3 nm. X-ray diffraction (XRD) pattern confirmed that the AgNPs presented a face-centered cubic (FCC) structure of crystalline silver. Energy dispersive of X-ray (EDX) spectrum and Fourier transform infrared spectroscopy (FTIR) analyses verified the existence of biomolecules, such as proteins, that participated in the formation and stabilization of AgNPs. Furthermore, the comparative study on cytotoxic effect of AgNPs indicated that the AgNPs exhibited higher biocompatibility towards human bronchial epithelial (HBE) cells than silver ions and exerted potent cytotoxic effect in a dose-dependent manner against human lung squamous cell carcinoma cells (HTB-182) and human lung adenocarcinoma cells (A549) with the concentrations ranging from 1 to 50 μg/mL.

The Design of a High Efficient DNA In-Situ Synthesis Apparatus Based on the Principle of Typography Technique

The paper describes a novel machine for in-situ synthesis of DNA Micro-arrays based on the use of typography technique. This apparatus was designed to incorporate platform for imprinting, precision printing stencil, one-way positioning device, manipulator, and liquid & gas delivery part and control part. The programmable logic controller was employed to control operation steps involving in biochip synthesis including locating and imprinting, and delivering the specific liquid. Finally, the control precision of system is measured using three coordinated instrument: the accuracy of location in X, Y axis is 5 µm, accuracy of printing template is 7 µm, and the repeated printing accuracy of whole machine is 16 µm. The result indicates that the design can completely meet the requirement of in situ synthesis of biochip based on the principle of typography printing.