The mechanism of Astragalus membranaceus' effects on the proliferation of human basal-like breast cancer cell line MDA-MB-468 from p53/MDM2 pathway

Abstract #2116

Background: Based on the expression of ER,PR and Her2, breast cancer is classified into several subtypes. Thereinto, basal-like type ("triple-negative" phenotype) is associated with poor prognosis. Patients with this type are unlikely to benefit from currently available targeted therapy. And some researches revealed traditional Chinese medicine could play an important role in breast cancer treatment. p53 mutations can be found in most of basal-like breast cancer patients and this type's cell lines. In our study, we mainly focused on the mechanism of Astragalus membranaceus' effect on the proliferation of MDA-MB-468 cell from p53/MDM2 pathway.
 Material and Methods: The MDA-MB-468 cells were intervened by Astragalus membranaceus Injection (AMI) which contains 1g/ml crude drugs. The effect of AMI on the proliferation of the MDA-MB-468 cells was detected by MTT assay and its time-effect relationship was observed by cell counting kit-8 (CCK-8) assay. At two days after AMI intervention, the mRNA expression of some indicators were assessed by Real-time Quantitative PCR, including p53, MDM2, EGFR, PIP, PI3K, Akt1, Akt2 and PTEN. The anti-proliferation effect of AMI on the cells proliferation was detected by MTT assay after PTEN gene was knocked down by the small interfering RNA (SiRNA), and the protein expressions of EGFR, p-Akt, MDM2 and p53 were obtained by in-cell western assay.
 Results: According to MTT assay, AMI could obviously inhibit the proliferation of the MDA-MB-468 cells (p<0.05) and the effect was stronger when combined with Tarceva (p<0.01); When the PTEN gene was knocked down, AMI only combined with Tarceva could inhibit the cells' proliferation (p<0.005). CCK-8 assay showed that the anti-proliferation effect of AMI was positively correlated with the intervention duration. Real-time Quantitative PCR revealed that AMI could up-regulate the PTEN gene expression (p<0.001) and down-regulate the p53 (p<0.01), MDM2 (p<0.01), Akt2 (p<0.001) and PIP (p<0.001) gene expressions. In-cell western assay indicated that p53 protein was down-regulated at 15min(p<0.05) and 1h(p<0.001), and p-Akt protein expression showed significant down-regulation at 15min(p<0.01), 30min(p<0.001) and 2d(p<0.001) after AMI intervene; when AMI combined with Tarceva, the duration of the down-regulation effect to p53 and p-Akt were all prolonged, and EGFR and MDM2 expressions were down-regulated(p<0.05, p<0.005). After PTEN SiRNA intervene, AMI down-regulate p53 (p<0.001), p-Akt (p<0.005) and EGFR (p<0.05) protein expressions; and its down-regulation effect to p-Akt reduced, but increased to p53, and EGFR.
 Discussion: AMI can significantly inhibit the proliferation of MDA-MB-468 cells and present a time-dependent manner. The effect became stronger after combined with Tarceva. The main mechanism of its anti-proliferation effect may be to activate the positive feedback loop of the p53/ MDM2 pathway. It negatively regulates the PI3K by up-regulating the PTEN gene expression to promote the phosphorylation at D3 point of PIP3, so Akt's phosphorylation level is down-regulated and the cells proliferation was inhibited.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2116.

Molecular recognition of acute myeloid leukemia using aptamers

Cell surface proteins can play important roles in cancer pathogenesis. Comprehensive understanding of the surface protein expression patterns of tumor cells and, consequently, the pathogenesis of tumor cells, depends on molecular probes against these proteins. To be effectively used for tumor diagnosis, classification and therapy, such probes would be capable of specific binding to targeted tumor cells. Molecular aptamers, designer DNA/RNA probes, can address this challenge by recognizing proteins, peptides and other small molecules with high affinity and specificity. Through a process known as cell-SELEX, we used live acute myeloid leukemia (AML) cells to select a group of DNA aptamers that can recognize acute myeloid leukemia cells with dissociation constants (Kds) in the nanomolar range. Interestingly, one aptamer (KH1C12), compared with two control cell lines (K562 and NB4), showed significant selectivity to the target AML cell line (HL60) and could recognize the target cells within a complex mixture of normal bone marrow aspirates. The other two aptamers KK1B10 and KK1D04 recognize targets associated with monocytic differentiation. Our studies demonstrate that the selected aptamers can be used as a molecular tool for further understanding surface protein expression patterns on tumor cells and thus providing a foundation for effective molecular analysis of leukemia and its subcategories.

Magnetotransport properties in K(0.50)CoO(2) single crystals

We have measured susceptibility and angle-dependent magnetoresistance (AMR) on K(0.50)CoO(2) single crystals. A possible magnetic structure similar to that of Na(0.5)CoO(2), a G-type anti-ferromagnetic (AF) structure (both in-plane and inter-plane are AF), is proposed. At ∼20 K, a loop is observed between zero-field-cooled (ZFC) and field-cooled (FC) susceptibility. The absolute value of magnetoresistance (MR) at 20 K is much larger than other cases with H applied within the ab plane. This could arise from the magnetic field being applied in the ab plane, leading to spin-flop of the small magnetic moment of Co(3.5-δ) sites at 20 K to form in-plane ferromagnetic ordering, as observed in Na(0.52)CoO(2).

Ocular complications of heart transplantation in a Chinese population

The purpose of this study was to investigate ocular complications among a group of patients on long-term, high-dose immunosuppression and corticosteroids for the maintenance of orthotopic heart transplants. Additionally, we provided information pertinent for the early diagnosis and treatment of eye diseases. In this study, we retrospectively assessed the clinical data of 138 patients with orthotopic heart transplantations from May 2000 to October 2005, including assessment of ophthalmic symptoms and signs, as well as the general condition, treatment, and prognosis. Of 138 transplant recipients examined (276 eyes), 47 eyes (17.0%) showed ocular surface diseases. Sixty-four (23.2%) had a posterior subcapsular cataract, and 16 (5.8%) corticosteroid glaucoma. Fifteen (5.6%) had ocular fundus diseases. Various ocular complications related to immunosuppression and corticosteroids appear among heart transplant patients. Cardiac surgeons and ophthalmologists must closely evaluate ocular symptoms in the posttransplantation period.

Avian metapneumovirus subtype A in China and subtypes A and B in Nigeria

In order to detect and characterize avian metapneumovirus, organs or swabs were collected from 697 chicken and 110 turkeys from commercial farms in Southwestern Nigeria and from 107 chickens from live bird markets in Southeastern China. In Nigeria, 15% and 6% of the chicken and turkey samples, respectively, and 39% of the chicken samples from China, were positive for aMPV genome by PCR. The sequence of a 400 nt fragment of the attachment protein gene (G gene) revealed the presence of aMPV subtype A in both Nigeria and Southeastern China. Essentially identical subtype A viruses were found in both countries and were also previously reported from Brazil and the United Kingdom, suggesting a link between these countries or a common source of this subtype. In Nigeria, subtype B was also found, which may be a reflection of chicken importations from most major poultry-producing countries in Europe and Asia. In order to justify countermeasures, further studies are warranted to better understand the metapneumoviruses and their impact on poultry production.

Prevalence of infections in residential care homes for the elderly in Hong Kong

OBJECTIVES

To study the prevalence of commonly occurring infections among residents of residential care homes for the elderly and their associated risk factors.

DESIGN

Point prevalence survey.

SETTING

Residential care homes for the elderly in Hong Kong.

PARTICIPANTS

Residential care homes for the elderly were treated as a cluster and about 30% of the residents from each home were selected by systematic sampling with bed numbers ending with the digits of 2, 5, and 8. Selected residents were invited to participate.

RESULTS

Data from 1603 residents aged 60 years or older from 43 residential care homes for the elderly were analysed. Most (85%) of the residents had underlying medical problems and 55% had more than one problem. The overall prevalence of infection among these residents was 5.7% (95% confidence interval, 4.2-7.1%). The three most common infections were: common cold or pharyngitis (1.9%; 95% confidence interval, 0.9-3.0%), skin and soft-tissue infections (1.4%; 0.5-2.4%), and symptomatic urinary tract infections (0.6%; 0.2-0.9%). Being 'bed-ridden' was a significant risk factor for skin and soft-tissue infections (odds ratio=3.1; 95% confidence interval, 1.4-6.9). Presence of a urinary catheter was a significant risk factor for symptomatic urinary tract infections (odds ratio=62.8; 95% confidence interval, 18.2-217.0). Chronic obstructive pulmonary disease was a significant risk factor for lower respiratory tract infection (odds ratio=16.5; 95% confidence interval, 3.4-81.2).

CONCLUSIONS

This is the first territory-wide prevalence survey of infections among residents in residential care homes for the elderly in Hong Kong. The data retrieved enable us to target our infection control programme in residential care homes for the elderly to those with a high prevalence. So as to monitor seasonal and secular trends, targeted regular surveillance is needed for better profiling of the actual situation.

Correlation between adiponectin polymorphisms and non-alcoholic fatty liver disease with or without metabolic syndrome in Chinese population

BACKGROUND

To investigate the effect of single nucleotide polymorphisms (SNP) 45 and 276 of the adiponectin gene on non-alcoholic fatty liver disease (NAFLD) with or without metabolic syndrome.

METHODS

A total of 165 NAFLD, 83 NAFLD with metabolic syndrome and 160 healthy controls from Chinese population were genotyped for the adiponectin gene (+45T>G and +276G>T) by PCR-restriction fragment length polymorphism methods. Plasma adiponectin and insulin levels were determined by enzyme-linked immunosorbent assay and radioimmunoassay, respectively. Insulin resistance (IR) was evaluated by using homeostasis model assessment of IR (HOMA-IR).

RESULTS

NAFLD with metabolic syndrome had further extent of IR and hypoadiponectinemia. No association of SNP45 or SNP276 was found in NAFLD or NAFLD with metabolic syndrome. Subjects carrying the G allele of SNP45 showed higher levels of triglyceride (TG), fasting blood sugar (FBS), HOMA, body mass index (BMI), and alanine transaminase (ALT), as well as lower plasma adiponectin levels. In the normal-weight group of SNP276, subjects carrying the G allele showed higher HOMA and subjects carrying the T allele showed lower BMI.

CONCLUSIONS

Our study observed further hypoadiponectinemia and IR in NAFLD with metabolic syndrome. The T45G and G276T of the adiponectin gene may not be the important determinants of NAFLD in Chinese people, but some of them still influence serum ALT, BMI, IR, lipid, glucose metabolism and plasma adiponectin concentration.