Molecular differences in triple negative breast cancer between race/ethnicities

Abstract #2089

Background: A disparity in prognosis of triple negative (TN) breast cancer (BC) has been observed between African American (AA) and Caucasian (CAU) race/ethnicities afflicted with this aggressive and invasive BC subtype. Etiological understanding of these differences involves accounting for several factors associated with phenotype and genotype. Here, we address the latter using the Illumina DASL (cDNA mediated, Annealing, Selection, Extension, and Ligation) assay to quantify mRNA expression of 512 breast cancer related genes in a cohort of 24 CAU and 56 AA TN BC tissues sourced from formalin-fixed, paraffin-embedded (FFPE) blocks.
 Material and Methods: The DASL assay was used to measure mRNA expression levels from FFPE sourced tissues in both cohorts of self-identified patients. CAU BC patients were obtained from St. Mary's Hospital, Montreal, Quebec and AA BC patients were obtained from Grady Hospital, Atlanta, Georgia. RNA extraction used the RNA High Pure Kit (Roche) and was taken from archival FFPE tissues either 5µm tissue sections or cores. Differential mRNA regulation was identified by Significance Analysis of Microarrays (SAM) software using a false discover rate (FDR) less than 1% and a two fold-change criteria to determine differential regulation.
 Results: In all, 33 genes were found differentially expressed between AA and CAU TN BC tumor samples, 32 of which were upregulated in the AA cohort, only 1 of which was upregulated in the CAU group. The upregulated gene in CAU TN BC was TFF1. Upregulated genes in the AA cohort (order of statistical significance according to SAM software) were KIF20A, EP300, AURKB, FGF4, C14orf155, USP22, EPOR, ZNF668, SCNN1G, MAPT, FLNB, EP400, LTA, ACOT11, RBP3, CSF3, E2F2, TGFB1, CCNE1, L1CAM, NDP, VWF, RHOB, FEN1, BIN1, KRT17, CDC42EP4, SERPINF1, CHI3L2, NES, BCL2, and RERG.
 Discussion: TFF1 upregulated in the CAU population, has been indicated as biomarker of favorable prognosis in endocrine therapy in clinical studies which is consistent with race/ethnicity disparities. The remaining genes upregulated in the AA cohort include transcription factors E2F2 and RBP3/E2F1 both with cyclin binding domains which may interact with CCNE1, extracellular and adhesion related genes KRT17, L1CAM and FGF4, genes associated with cell cycle AURKB, EP400, and EP300 (activator of HIF-1A). Several RAS related genes were also found differentially expressed in the AA cohort including RHOB, RERG, BIN1, and EPOR. Moreover, it is worth mentioning that BCL2 which is expressed in the aggressive mammary cancer cell line MCF-7 was also found upregulated in the AA cohort. These initial findings suggest that several differentially regulated genes between AA and CAU race/ethnicities may account for the disparity in outcomes resultant in these populations. These initial data warrant further investigation which is currently ongoing.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2089.

The Leser-Trélat sign is associated with nasopharyngeal carcinoma: case report and review of cases reported in China

The sign of Leser-Trélat (LT) is defined as the sudden eruption of multiple seborrhoeic keratoses (SKs), or increase in the number and size of existing SKs, associated with an underlying malignancy. A 75-year-old man was admitted to our hospital with dyspnoea and multiple verrucous papules that had been developing gradually over the previous 30 years. During the 3 months before presentation, the number of SKs on his chest and back had increased rapidly. A diagnosis of nasopharyngeal carcinoma was made based on results of computed tomography, endoscopy and biopsy examinations. The patient is receiving radiotherapy at present. To our knowledge, this is the first case of the Leser-Trélat sign associated with nasopharyngeal carcinoma.

Apoptosis-inducing effect of cinobufacini, Bufo bufo gargarizans Cantor skin extract, on human hepatoma cell line BEL-7402

Cinobufacini, a water-soluble preparation of Chinese medicine, is extracted from the skin of Bufo bufo gargarizans Cantor. The present study sought to investigate the effects of Cinobufacini on apoptosis of the hepatocellular carcinoma cell line BEL-7402. Cell viability was measured by methyl thiazolyl tetrazolium assay. Cell morphology was observed by Hoechst 33258 staining. Western blotting analysis was used to detect Bax and Bcl-2 expression. Results indicated that Cinobufacini inhibited the proliferation of BEL-7402 cells in a dose and time-dependent manner. Marked morphological changes indicative of apoptosis were observed after treatment with different concentrations of Cinobufacini. Western blot analysis showed that Bcl-2 expression was down-regulated while Bax expression was upregulated. Thus, Cinobufacini may have a significant　apoptosis-inducing effect on BEL-7402 cells, and this could prove useful for further anti-cancer research.

Identification of osteo-adipo progenitor cells in fat tissue

OBJECTIVES

In this study, a group of cells that expressed both osteogenic and adipogenic characters was identified from murine adipose stromal cells.

MATERIALS AND METHODS

These cells could be enriched in the Sca-1-1 population and express both osteogenic and adipogenic genes. Osteogenic induction enhanced expression of osteogenic genes and inhibited expression of adipogenic genes, while adipogenic induction enhanced expression of adipogenic genes and inhibited expression of osteogenic genes. These cells have been called osteo-adipo progenitors (OAPs).

RESULTS

OAPs expressed transcription factor runt-related transcription factor 2 (RUNX2) and peroxisome proliferator-activated receptor-gamma (PPAR-gamma) proteins in cytoplasm. When OAPs were cultured in adipogenic medium, PPAR-gamma moved to the nucleus and the cells differentiated into adipocytes, while the RUNX2 remained in the cytoplasm. In contrast, when OAPs were cultured in osteogenic medium, RUNX2 moved to the nucleus and the cells differentiated to osteocytes, while the PPAR-gamma remained in the cytoplasm.

CONCLUSIONS

These experiments suggest that osteoblasts and adipocytes share a common predecessor, the OAP, in murine adipose stromal cells.

Effect of benzyl-N-acetyl-α-galactosaminide on KL-6 mucin expression and invasive properties of a human pancreatic carcinoma cell line

KL-6 mucin is a type of MUC1 mucin and its aberrant expression has been shown to be associated with aggressive metastasis and poor clinical outcome in tumors. The present study is to investigate the effects of benzyl-N-acetyl-α-galactosaminide (GalNAc-O-bn), an O-glycosylation inhibitor, on KL-6 mucin expression and invasive properties of a human pancreatic carcinoma cell line, Suit-2 cells. Expression profiles of KL-6 mucin in the cells pretreated with or without 5 mM GalNAc-O-bn for 48 h were examined by Western blotting and immunocytochemical staining and invasive properties were examined by transwell chamber assay. Western blotting and immunocytochemical staining showed that the expression profiles of KL-6 mucin changed significantly after GalNAc-O-bn treatment. Meanwhile, the invasive ability of Suit-2 cells decreased significantly after GalNAc-O-bn treatment (p < 0.05). These results suggest that glycosylation of KL-6 mucin may be closely related to aggressive behaviors of pancreatic cancer cells like metastasis and invasion.

Japan-China Joint Medical Workshop on Drug Discoveries and Therapeutics 2008: The need of Asian pharmaceutical researchers' cooperation

The Japan-China Joint Medical Workshop on Drug Discoveries and Therapeutics 2008 (JCMWDDT 2008) was held from September 29 to October 1, 2008 at The University of Tokyo, Tokyo, Japan. JCMWDDT is an international workshop that is mainly organized by Asian editorial members of Drug Discoveries & Therapeutics (<a href="http://www.ddtjournal.com/home" class="blue">http://www.ddtjournal.com/home</a>) for the purpose of promoting research exchanges in the field of drug discovery and therapeutic. This year's JCMWDDT is the second workshop and focused particularly on novel development and technological innovation of anti-influenza agents. The workshop began with an announcement by the Japanese Co-chairperson, Dr. Sekimizu (Department of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan; Editorin- Chief of Drug Discoveries & Therapeutics, DDT) followed by a speech by the Chinese Co-chairperson, Dr. Wenfang Xu (School of Pharmaceutical Sciences, Shandong University, Shandong, China; Editor in China Office of DDT), with additional speeches by Dr. Norio Matsuki (The University of Tokyo, Japan; Editor of DDT) and Dr. Guanhua Du (Chinese Academy of Medical Science, China; Editor of DDT). Fifty-nine titles were presented in 6 specialized sessions (Research Advances in Drug Discoveries and Therapeutics, Drug Synthesis/Clinical Therapeutics, Medicinal Chemistry/Natural Products, Anti-influenza Drugs, Anti-infection/antiviral Drugs, Biochemistry/Molecular Biology /Pharmacology) and a poster session (Drug Discov Ther 2008; 2, Suppl; available at <a href="http://www.ddtjournal.com/Announce/index.htm" class="blue">http://www.ddtjournal.com/Announce/index.htm</a>). An annual outbreak of avian influenza in Asian countries including China and Japan has sparked fears that the virus will mutate and then cause an epidemic in humans. Therefore, Asian researchers need to work together to control this infection. This year's JCMWDDT helped provide an opportunity to reiterate the crucial role of medicinal chemistry in conquering influenza and created an environment for cooperative research in Asian countries. (reported on October 1st, with grateful thanks to all participants) Main program Session I. Research Advances in Drug Discoveries and Therapeutics ● Design, synthesis and preliminary activity assay of influenza virus neuraminidase inhibitors by Wenfang Xu (Shandong University, China) ● Infection disease models with silkworms to evaluate the therapeutic effects of drug candidates by Kazuhisa Sekimizu (The University of Tokyo, Japan) ● Japan's governmental approaches to facilitate drug development process by Makoto Shimoaraiso (Ministry of Foreign Affairs of Japan, Japan) ● Effective detection of the epidermal growth factor receptor mutation by the peptide nucleic acid-locked nucleic acid PCR Clamp by Sakuo Hoshi (The University of Tokyo Hospital, Japan) ● Design and synthesis of p53-MDM2 binding inhibitors by Yongzhou Hu (Zhejiang University, China) Session II. Drug Synthesis/Clinical Therapeutics ● Pharmacogenomics-based clinical studies using a novel fully-automated genotyping system by Setsuo Hasegawa (Sekino Clinical Pharmacology Clinic, Japan) ● Synthesis and biological evaluation of pentacyclic triterpenes as anti-tumor agents by Hongbin Sun (China Pharmaceutical University, China) ● Drug discovery and therapeutics using silkworm as experimental animal by Yasuyuki Ogata (The University of Tokyo, Japan) ● Novel selective estrogen recetpor modulators (SERMs) with unusual structure and biological activities by Haibing Zhou (Wuhan University, China) Session III. Medicinal Chemistry/Natural Products ● Synthesis and properties of isonucleosides incorporated oligonucleotides by Zhenjun Yang (Peking University, China) ● Isolation of antiviral compounds from plant resources using silkworm bioassay by Yutaka Orihara (The University of Tokyo, Japan) ● Synthesis and structural modifcation of tasiamide and the effect of these modifications on in vitro anticancer activity by Yingxia Li (Ocean University of China, China) ● Spirohexalines A and B, novel undecaprenyl pyrophosphate inhibitors produced by Penicillium sp. FKI-3368 by Junji Inokoshi (Kitasato University, Japan) ● Nosokomycins, novel anti-MRSA antibiotics, produced by Streptomyces sp. K04-0144 by OR. Uchida (Kitasato University, Japan) ● In vivo screening for antimicrobial activity of Thai Herbal Medicines using silkworm model by Santad Chanprapaph (Chulalongkorn University, Thailand) ● Novel electrochemical sensor of nitric oxide for screening anti-aging Traditional Chinese Medicine by Zilin Chen (Wuhan University, China) ● Polysacchride from green tea purified by silkworm muscle contraction assay induces innate immunity by increasing the expression of various inflammatory cytokine mRNA in human leukocytes by Saphala Dhital (The University of Tokyo, Japan) Session IV. Anti-influenza Drugs ● Structure-activity relationship of flavonoids as influenza virus neuraminidase inhibitors and their in vitro anti-viral activities by Guanhua Du (Chinese Academy of Medical Sciences and Peking Union Medical College, China) ● Mechanisms and consequences of phagocytosis of influenza virus-infected cells by Yoshinobu Nakanishi (Kanazawa University, Japan) ● Nuclear export inhibitors; a possible target for novel anti-influenza viral drugs by Ken Watanabe (Nagasaki University, Japan) ● Catalytic asymmetric synthesis of oseltamivir phosphate directing toward its stable worldwide supply by Motomu Kanai (The University of Tokyo, Japan) ● Clinical effects of probiotic bifidobacterium in the prevention of influenza virus infections and allergic diseases by Jin-zhong Xiao (Morinaga Milk Industry Co., Ltd., Japan) ● Production of anti-influenza PR8-scFv using a phage display by Normaiza Zamri (Tokai University, Japan) Session V. Anti-infection/Antiviral Drugs ● Emerging infectious diseases and anti-viral drugs: Urgent need to develop effective drugs which cause less resistant virus by Nobuyuki Kobayashi (Nagasaki University, Japan) ● Design, synthesis and antiviral evaluation of novel heterocyclic compounds as HIV-1 NNRTIs by Xinyong Liu (Shandong University, China) ● Antiviral drug screening from microbial products by Eisaku Tsujii (Astellas Pharma Inc., Japan) ● Viral factors that determine the natural course of chronic hepatitis B viral infection by Hiroshi Yotsuyanagi (The University of Tokyo, Japan) ● Effect of andrographolide derivatives having α-glucosidase inhibition, on HBsAg, HBeAg secretion in HepG2 2.2.15 cells by Hongmin Liu (Zhengzhou University, China) ● Current and future antiviral therapy for influenza by Hideki Asanuma (Tokai University, Japan) ● Establishment of an HIV-based pseudotyping system as a safe model for screening inhibitors on bird flu H5N1 entry by Ying Guo (Peking Union Medical Collegee Chinese Academy of Medical Sciences, China) ● Strategy of discovery for novel antibiotics using silkworm infection model by Hiroshi Hamamoto (The University of Tokyo, Japan) ● Potent neuraminidase inhibitors and anti-inflammatory substances from Chaenomeles speciosa by Li Zhang (Chinese Academy of Medical Sciences and Peking Union Medical College, China) ● High-throughput screening assay for hepatitis C virus helicase inhibitors using fluorescence-quenching phenomenon by Hidenori Tani (Waseda University and National Institute of Advanced Industrial Science and Technology, Japan) Session VI. Biochemistry/Molecular Biology/Pharmacology ● A novel conjugate of low-molecular-weight heparin and Cu,Zn-superoxide dismutase: Study on its mechanism in preventing brain reperfusion injury after ischemia in gerbils by Fengshan Wang (Shandong University, China) ● A novel gene fudoh in SCCmec region regulates the colony spreading ability and virulence in Staphylococcus aureus by Chikara Kaito (The University of Tokyo, Japan) ● Water soluble fluorescent boronic acid sensors for tumor cell-surface saccharide by Hao Fang (Shandong Unviersity, China) ● Molecular characterization of the biosynthetic enzyme for the biotechnological production of tetrahydrocannabinol, the active constituent of marijuana by Futoshi Taura (Kyushu University, Japan) ● Galloyl cyclic-imide derivative CH1104I inhibits tumor invasion via suppressing matrix metalloproteinase activity by Xianjun Qu (Shandong University, China) ● Neuroprotection by inhibition of GAPDH-MAO B mediated cell death induced by ethanol by Xiao-Ming Ou (University of Mississippi Medical Center, USA).

Influence of different recombinant systems on the cooperativity exhibited by cytochrome P4503A4

1. The in vitro cooperativity exhibited by cytochrome P450 (CYP) 3A4 is influenced by the nature of the recombinant system in which the phenomenon is studied. Diclofenac, piroxicam and R-warfarin were used as model substrates, and quinidine was the effector. 2. The 5-, 5'- and 10-hydroxylation of diclofenac, piroxicam and R-warfarin, respectively, were enhanced five- to sevenfold by quinidine in human liver microsomal incubations. Whereas these cooperative drug interactions were apparent in incubations with CYP3A4 expressed in human lymphoblast cells, similar phenomena were not observed with the enzyme expressed in insect cells. 3. Insect cell microsomes were treated with a detergent and CYP3A4 was solubilized into a buffer medium. In incubations with CYP3A4 'freed' from its host membrane, the 5-hydroxylation of diclofenac increased with increasing quinidine concentrations, reaching a maximal eightfold elevation relative to controls. The metabolism of piroxicam and warfarin was similarly enhanced by quinidine. 4. Kinetically, enhancement by quinidine of the 5-hydroxylation of diclofenac in incubations with solubilized CYP3A4 was characterized by increases in the rate of metabolism with little change in the substrate-binding affinity. Conversely, the 3-hydroxylation of quinidine was not affected by diclofenac. 5. The data suggest that certain properties of CYP3A4 are masked by expression of the protein in insect cells and reinforce the concept that the enzyme possesses multiple binding domains. The absence of cooperative drug interactions with quinidine when CYP3A4 was expressed in insect cells might be due to an absence of enzyme conformation changes on quinidine binding, or the inability of quinidine to gain access to a putative effector-binding domain. 6. Caution should be exercised when comparing models for CYP3A4 cooperativity derived from different recombinant preparations of the enzyme.

Attenuating pregnane X receptor (PXR) activation: A molecular modelling approach

Recent studies have demonstrated that the pregnane X receptor (PXR) is a key regulator of cytochromes P450 3A (e.g. CYP3A4 in human) gene expression. As a result, activation of PXR may lead to CYP3A4 protein over-expression. Because induction of CYP3A4 could result in clinically important drug drug interactions, there has been a great interest in reducing the possibility of PXR activation by drug candidates in drug-discovery programmes. In order to provide structural insight for attenuating drug candidate-mediated PXR activation, we used a docking approach to study the structure activity relationship for PXR activators. Based on our docking models, it is proposed that introducing polar groups to the end of an activator should reduce its human PXR (hPXR) activity via destabilizing interactions in the hydrophobic areas of the PXR ligand-binding pocket. A number of analogues that incorporate these structural features then were designed and synthesized, and they exhibited significantly lower hPXR activation in a transactivation assay and decreased CYP3A4 induction in a human hepatocytes-based assay. In addition, an example in which attenuating hPXR activation was achieved by sterically destabilizing the helices 11 and 12 of the receptor is presented.

Polymorphism of HLA-DRB1, -DQB1 and -DPB1 genes in Bai ethnic group in southwestern China

In this work, polymorphism of human leukocyte antigen (HLA)-DRB1, -DQB1 and -DPB1 genes was detected using polymerase chain reaction-sequence-based typing method in 128 healthy unrelated volunteers from the Bai ethnic group of Yunnan province of southwest China. Among all the 28 alleles detected for the DRB1 gene, the most common allele was DRB1*120201 with a frequency of 16.41%, followed by DRB1*090102, DRB1*080302, DRB1*1404, DRB1*150101, DRB1*140101 and DRB1*160201, with frequencies of 10.16%, 9.77%, 9.38%, 8.98%, 8.59% and 8.21%, respectively. Among 19 DQB1 alleles detected, the most frequent allele was DQB1*030101/0309 (35.94%), followed by DQB1*050201 (11.33%), DQB1*060101/060103 (10.54%) and DQB1*0401 (10.16%). For the DPB1 locus, the most common alleles were DPB1*0501 (42.19%), DPB1*1301 (13.28%), DPB1*020102 (10.93%) and DPB1*040101 (9.77%). The comparison of HLA class II allele frequencies of Bais with those of other Chinese populations suggested that the Bai ethnic group belonged to the southern group of Chinese.

Effect of soft metal gasket contacts on contact resistance, energy deposition, and plasma expansion profile in a wire array Z pinch

Soft metal gaskets (indium and silver) were used to reduce contact resistance between the wire and the electrode in an aluminum wire Z pinch by more than an order of magnitude over the best weighted contact case. Clamping a gasket over a Z-pinch wire compresses the wire to the electrode with a greater normal force than possible with wire weights. Average contact resistance was reduced from the range of 100-3000 Omega (depending on wire weight mass) to 1-10 Omega with soft metal gaskets. Single wire experiments (13 microm Al 5056) on a 16 kA, 100 kV Marx bank showed an increase in light emission (97%) and emission volume (100%) of the plasma for the reduced contact resistance cases. The measured increases in plasma volume and light emission indicate greater energy deposition in the ablated wire. Additionally, dual-wire experiments showed plasma edge effects were significantly decreased in the soft metal gasket contact case. The average height of the edge effects was reduced by 51% and the width of the edge effects was increased by 40%, thus the gasket contact case provided greater axial uniformity in the plasma expansion profile of an individual wire.

Comparing Multiple Sensitivities and Specificities with Different Diagnostic Criteria: Applications to Sexual Abuse and Sexual Health Research

When comparing sensitivities and specificities from multiple diagnostic tests, particularly in biomedical research, the different test kits under study are applied to groups of subjects with the same disease status for a disease or medical condition under consideration. Although this process gives rise to clustered or correlated test outcomes, the associated inference issues are well recognized and have been widely discussed in the literature. In mental health and psychosocial research, sensitivity and specificity have also been widely used to study the reliability of instrument for diagnosing mental health and psychiatric conditions and assessing certain behavioral patterns. However, unlike biomedical applications, outcomes are often obtained under varying reference standards or different diagnostic criteria, precluding the application of existing methods for comparing multiple diagnostic tests to such a research setting. In this paper, we develop a new approach to address these problems (including that of missing data) by extending recent work on inference using inverse probability weighted estimates. The approach is illustrated with data from two studies in sexual abuse and health research as well as a limited simulation study, with the latter used to study the performance of the proposed procedure.

No association found between the promoter variants of TNF-alpha and diabetic retinopathy in Chinese patients with type 2 diabetes

PURPOSE

Necrosis tumor factor (TNF) is known to be associated with diabetic retinopathy (DR). The objective of this study was to examine the genetic variations of TNF-alpha and assess their possible relationship to DR in type 2 diabetic patients in the Chinese population.

MATERIALS AND METHODS

We conducted a case-control association study between the promoter variants of TNF-alpha and diabetic retinopathy in Chinese patients with type 2 diabetes. We selected three variants in the promoter region of TNF-alpha, namely rs1800629, rs1041981, and rs2857713.

RESULTS

No individual SNP nor any haplotype was found to be associated with DR in our study.

CONCLUSION

This is the first study to report TNF-alpha polymorphisms in patients with DR in the Chinese population. The results suggest that the variants among the promoter of TNF-alpha are unlikely to play a major role in the susceptibility to DR in Chinese patients with type 2 diabetes.

Effect of the anticoagulant ethylenediamine tetra-acetic acid (EDTA) on the estimation of pharmacokinetic parameters: A case study with tigecycline and ciprofloxacin

Tigecycline and ciprofloxacin were employed as the model compounds to study the effect of the anticoagulant ethylenediamine tetra-acetic acid (EDTA), which is used during plasma sample preparations, on the determination of pharmacokinetic parameters. The pharmacokinetic parameters were determined in rats following intravenous infusion with blood samples collected in serum separators, with either EDTA- or heparin-coated tubes. The blood-to-plasma (B:P) partition ratio and plasma protein binding were determined in vitro in rat or human blood collected in either EDTA- or heparin-coated tubes. Drug concentrations were quantified by liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) analysis. In tigecycline-treated rats drug concentrations were twofold lower in EDTA plasma, leading to a twofold lower area under plasma concentration-time curve (AUC) and twofold higher plasma clearance values as compared with those obtained from heparin plasma. No differences were noted in the pharmacokinetic parameters obtained from heparin-treated plasma versus serum. The B:P partition ratio and unbound fraction for tigecycline were significantly higher in EDTA-treated blood. When normalized to the B:P partition ratios, the tigecycline blood clearance values were identical between samples collected in EDTA- or heparin-coated tubes. Similar but smaller differences were observed for ciprofloxacin. It was concluded that EDTA might compete with tigecycline and ciprofloxacin for chelating metal ions and thus affect drug partition between blood and plasma compartments, leading to inaccurate measurement of pharmacokinetic parameters in plasma.

Recent advances in P-glycoprotein-mediated multidrug resistance reversal mechanisms

Expression of the multidrug resistance (MDR) phenotype is responsible for chemotherapy failure in numerous cancers. Overexpression of mdr1 gene-encoded permeability glycoprotein (P-gp) is known to play a pivotal role in the development of this phenotype. The role of P-gp has been proposed as an important goal in the design of chemotherapy strategies. However, modulation of P-gp activity by chemotherapy has limited possibilities because of toxicity and poor specificity. In this article, we review the latest advancements in different potential P-gp-mediated MDR reversal mechanisms as well as the methods of evaluating MDR reversal activity, which would be helpful in finding novel MDR reversal agents (or chemosensitizers).

Recent advances in P-glycoprotein-mediated multidrug resistance reversal mechanisms

Expression of the multidrug resistance (MDR) phenotype is responsible for chemotherapy failure in numerous cancers. Overexpression of mdr1 gene-encoded permeability glycoprotein (P-gp) is known to play a pivotal role in the development of this phenotype. The role of P-gp has been proposed as an important goal in the design of chemotherapy strategies. However, modulation of P-gp activity by chemotherapy has limited possibilities because of toxicity and poor specificity. In this article, we review the latest advancements in different potential P-gp-mediated MDR reversal mechanisms as well as the methods of evaluating MDR reversal activity, which would be helpful in finding novel MDR reversal agents (or chemosensitizers).

DH1, a LOB domain-like protein required for glume formation in rice

T-DNA tagging is a high throughput strategy for identifying and cloning functional genes in plants. In this study, we screened 4416 lab-created T(1) rice T-DNA tagged lines and identified a mutant, designated dh1 (degenerated hull1), with phenotype of degenerated hull and naked pistils and stamens. Approximately 60% florets on the dh1 panicle defected in forming normal palea and lemma. Instead, they formed degenerative velum-like or filamentous organs accompanying with the lack of lodicules, stamens and pistils at different degree. A 361 bp of genomic sequence flanking the T-DNA isolated using TAIL-PCR (Thermal asymmetric interlaced PCR) co-segregated with the mutation phenotype. Results of blastn and gene prediction revealed the T-DNA inserted into the promoter region of a function-predicted gene at 283 bp upstream of its transcription start site (TSS). The predicted gene encoded a LOB (Lateral Organ Boundaries) domain-like protein. RT-PCR analyses indicated the transcription level of target candidate gene, DH1, decreased significantly in dh1 mutant. RNAi aimed at DH1 in wild type plants could partially result in the mutation phenotype of dh1. DH1 could also rescue the mutation phenotype in the complement experiment. The result of transformation by a fused expression vector, pDH1::GFP, revealed that DH1 had the keen spatial and temporal characteristics of expressing at axillary bud, young panicle and floral organs but not at root, leaf, node and culm, and strongly expressing at young tissues but weakly at mature organs. The dh1 presented severer mutation phenotype under relatively longer daylight than under shorter daylight implied that shorter daylight induced the expression of gene(s) redundant to DH1 in function and partially compensated for the loss-of-function. It is the first time to report the LOB-domain gene participating in the development of floral organs in rice.

Photoprotection of bacterial-derived melanin against ultraviolet A-induced cell death and its potential application as an active sunscreen

BACKGROUND

The increase in the incidence of non-melanoma skin tumours, photoaging, and immunosuppression demand for more effective sunscreen on ultraviolet A (UVA) irradiation.

OBJECTIVES

The aim of the study is to evaluate the photoprotective effects of a bacterial-derived melanin against UVA-induced damages in vitro and in vivo. Methods Human fibroblasts were used to assess the role of the bacterial-derived melanin on cell viability against UVA. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and nuclear morphology were employed to evaluate the photoprotection at the cellular level. Fluorometric assays were performed to detect the formation of reactive oxygen species (ROS) in the cells. Evaluations of the bacterial-derived melanin as a sunscreen were measured by transmission test and persistent pigment darkening on human skin.

RESULTS

Bacterial-derived melanin efficiently scavenged ROS in the fibroblasts after UVA irradiation. The cell viability of xeroderma pigmentosum (XP) fibroblast treated with varied doses of melanin increased dramatically in comparison with untreated control and the treated XP fibroblasts became more resistant to UVA-induced apoptosis than normal fibroblasts. Although the relative transmission didn't change too much with different concentration of bacterial-derived melanin, this melanin could keep UVA-irradiated skin from pigment darkening and act as an active sunscreen on skin.

CONCLUSIONS

The bacterial-derived melanin provided significant protection to fibroblast cell and human skin against the UVA radiation. It has the potential to be developed as an active sunscreen for the patients with photosensitivity skin to sun exposure.