Overexpression of angiotensin II type 1 receptor in breast cancer cells induces epithelial-mesenchymal transition and promotes tumor growth and angiogenesis

The angiotensin II type I receptor (AGTR1) has been implicated in diverse aspects of human disease, from the regulation of blood pressure and cardiovascular homeostasis to cancer progression. We sought to investigate the role of AGTR1 in cell proliferation, epithelial-mesenchymal transition (EMT), migration, invasion, angiogenesis and tumor growth in the breast cancer cell line MCF7. Stable overexpression of AGTR1 was associated with accelerated cell proliferation, concomitant with increased expression of survival factors including poly(ADP-ribose) polymerase (PARP) and X-linked inhibitor of apoptosis (XIAP), as well as extracellular signal-regulated kinase (ERK) activation. AGTR1-overexpressing MCF7 cells were more aggressive than their parent line, with significantly increased activity in migration and invasion assays. These observations were associated with changes in EMT markers, including reduced E-cadherin expression and increased p-Smad3, Smad4 and Snail levels. Treatment with the AGTR1 antagonist losartan attenuated these effects. AGTR1 overexpression also accelerated tumor growth and increased Ki-67 expression in a xenograft model. This was associated with increased tumor angiogenesis, as evidenced by a significant increase in microvessels in the intratumoral and peritumoral areas, and enhanced tumor invasion, with the latter response associated with increased EMT marker expression and matrix metallopeptidase 9 (MMP-9) upregulation. In vivo administration of losartan significantly reduced both tumor growth and angiogenesis. Our findings suggest that AGTR1 plays a significant role in tumor aggressiveness, and its inhibition may have therapeutic implications.

A highly sensitive and selective impedimetric aptasensor for interleukin-17 receptor A

Interleukin-17 receptor A (IL-17RA) has been recognized as a valuable biomarker for diverse diseases, including autoimmune diseases. In this work, an electrochemical biosensor with great sensitivity and selectivity toward IL-17RA was fabricated using an IL-17RA aptamer (Kd=14.00nM) for the first time. The aptasensor was manufactured using electrodeposition of gold nanoparticles, and then quantitative detection of IL-17RA was performed based on impedimetry. The developed sensor exhibited a superior analytical performance for IL-17RA with a wide dynamic range of 10-10,000pg/mL in buffer and a detection limit of 2.13pg/mL, which is lower than that of commercially available ELISA kits. In addition, we validated the high specificity of the designed aptasensor to only IL-17RA, which showed good sensitivity even in human serum solution. Furthermore, the detection of the differentiated HL-60 cells expressing IL-17RA was successfully performed. Clinical applicability of the sensor was also demonstrated utilizing neutrophils separated from asthma patients. It is expected that the fabricated aptasensor will become an excellent diagnostic platform for IL-17RA-mediated diseases.

Electrochemical aptasensor of cardiac troponin I for the early diagnosis of acute myocardial infarction

Cardiac troponin I (cTnI) is well-known as a promising biomarker for the early diagnosis of acute myocardial infarction (AMI). In this work, single-stranded DNA aptamers against cTnI were identified by the Systematic Evolution of Ligands by Exponential enrichment (SELEX) method. The aptamer candidates exhibited a high selectivity and sensitivity toward both cTnI and the cardiac Troponin complex. The binding affinities of each aptamer were evaluated based on their dissociation constants (Kd) by surface plasma resonance. The Tro4 aptamer that had the highest binding capacity to cTnI showed a very low Kd value (270 pM) compared with that of a cTnI antibody (20.8 nM). Furthermore, we designed a new electrochemical aptasensor based on square wave voltammetry using ferrocene-modified silica nanoparticles. The developed aptasensor demonstrated an excellent analytical performance for cTnI with a wide linear range of 1-10 000 pM in a buffer and a detection limit of 1.0 pM (24 pg/mL; S/N = 3), which was noticeably lower than the cutoff values (70-400 pg/mL). The specificity of the aptamers was also examined using nontarget proteins, demonstrating that the proposed sensor responded to only cTnI. In addition, cTnI was successfully detected in a human serum albumin solution. On the basis of the calibration curve that was constructed, the concentrations of cTnI in a solution supplemented with human serum were effectively measured. The calculated values correlated well with the actual concentrations of cTnI. It is anticipated that the highly sensitive and selective aptasensor for cTnI could be readily applicable for the accurate diagnosis of AMI.

Dual aptamer-functionalized silica nanoparticles for the highly sensitive detection of breast cancer

In this study, we synthesized dual aptamer-modified silica nanoparticles that simultaneously target two types of breast cancer cells: the mucin 1 (MUC1)(+) and human epidermal growth factor receptor 2 (HER2)(+) cell lines. Dual aptamer system enables a broad diagnosis for breast cancer in comparison with the single aptamer system. The dye-doped silica nanoparticles offer great stability with respect to photobleaching and enable the accurate quantification of breast cancer cells. The morphological and spectroscopic characteristics of the designed Dual-SiNPs were demonstrated via diverse methods such as DLS, zeta potential measurements, UV-vis spectroscopy, and fluorescence spectroscopy. Negatively charged Dual-SiNPs with a homogeneous size distribution showed robust and strong fluorescence. In addition, Dual-SiNPs did not affect cell viability, implying that this probe might be readily available for use in an in vivo system. Through ratio optimization of the MUC1 and HER2 aptamers, the binding capacities of the Dual-SiNPs to both cell lines were maximized. Based on Dual-SiNPs, a highly sensitive quantification of breast cancer cells was performed, resulting in a detection limit of 1 cell/100 μL, which is significantly lower compared with those reported in other studies. Moreover, the developed detection platform displayed high selectivity for only the MUC1(+) and HER2(+) cell lines. It is expected that this valuable diagnostic probe will be a noteworthy platform for the diagnosis and prognosis of breast cancer.

Structural insights into Escherichia coli polymyxin B resistance protein D with X-ray crystallography and small-angle X-ray scattering

BACKGROUND

Polymyxin B resistance protein D (PmrD) plays a key role in the polymyxin B-resistance pathway, as it is the signaling protein that can act as a specific connecter between PmrA/PmrB and PhoP/PhoQ. We conducted structural analysis to characterize Escherichia coli (E. coli) PmrD, which exhibits different features compared with PmrD in other bacteria.

RESULTS

The X-ray crystal structure of E. coli PmrD was determined at a 2.00 Å resolution, revealing novel information such as the unambiguous secondary structures of the protein and the presence of a disulfide bond. Furthermore, various assays such as native gel electrophoresis, surface plasmon resonance (SPR), size-exclusion chromatography, dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS) measurements, were performed to elucidate the structural and functional role of the internal disulfide bond in E. coli PmrD.

CONCLUSIONS

The structural characteristics of E. coli PmrD were clearly identified via diverse techniques. The findings help explain the different protective mechanism of E. coli compared to other Gram-negative bacteria.

Ultra-effective photothermal therapy for prostate cancer cells using dual aptamer-modified gold nanostars

Although various studies related to nanoparticles-based photothermal therapy have been actively performed, an epoch-making photothermolysis therapy exhibiting both high selectivity and efficiency has yet not been discovered. For the first time, we have developed novel valuable therapeutic complexes, namely, dual aptamer-modified gold nanostars, for the targeting of prostate cancers, including PSMA(+) and PSMA(-) cells. The synthesized probes were characterized through several techniques, including UV-VIS spectral analysis, DLS analysis, zeta potential measurements, and TEM imaging, and were subsequently subjected to cytotoxicity tests, cell uptake confirmation, and in vitro photothermal therapy. The homogeneously well-fabricated nanostars presented high selectivity to prostate cancer cells and extremely high efficiency for therapy using an 808 nm laser under an irradiance of 0.3 W cm^-2, which is lower than the permitted value for skin exposure (0.329 W cm^-2). It is anticipated that this novel photothermal agent will become the general platform for targeted therapy.

Characterization of multi-functional properties and conformational analysis of MutS2 from Thermotoga maritima MSB8

The MutS2 homologues have received attention because of their unusual activities that differ from those of MutS. In this work, we report on the functional characteristics and conformational diversities of Thermotoga maritima MutS2 (TmMutS2). Various biochemical features of the protein were demonstrated via diverse techniques such as scanning probe microscopy (SPM), ATPase assays, analytical ultracentrifugation, DNA binding assays, size chromatography, and limited proteolytic analysis. Dimeric TmMutS2 showed the temperature-dependent ATPase activity. The non-specific nicking endonuclease activities of TmMutS2 were inactivated in the presence of nonhydrolytic ATP (ADPnP) and enhanced by the addition of TmMutL. In addition, TmMutS2 suppressed the TmRecA-mediated DNA strand exchange reaction in a TmMutL-dependent manner. We also demonstrated that small-angle X-ray scattering (SAXS) analysis of dimeric TmMutS2 exhibited nucleotide- and DNA-dependent conformational transitions. Particularly, TmMutS2-ADPnP showed the most compressed form rather than apo-TmMutS2 and the TmMutS2-ADP complex, in accordance with the results of biochemical assays. In the case of the DNA-binding complexes, the stretched conformation appeared in the TmMutS2-four-way junction (FWJ)-DNA complex. Convergences of biochemical- and SAXS analysis provided abundant information for TmMutS2 and clarified ambiguous experimental results.

A highly sensitive aptasensor towards Plasmodium lactate dehydrogenase for the diagnosis of malaria

Finding a highly sensitive diagnostic technique for malaria has challenged scientists for the last century. In the present study, we identified versatile single-strand DNA aptamers for Plasmodium lactate dehydrogenase (pLDH), a biomarker for malaria, via the Systematic Evolution of Ligands by EXponential enrichment (SELEX). The pLDH aptamers selectively bound to the target proteins with high sensitivity (K(d)=16.8-49.6 nM). The selected aptamers were characterized using an electrophoretic mobility shift assay, a quartz crystal microbalance, a fluorescence assay, and circular dichroism spectroscopy. We also designed a simple aptasensor using electrochemical impedance spectroscopy; both Plasmodium vivax LDH and Plasmodium falciparum LDH were selectively detected with a detection limit of 1 pM. Furthermore, the pLDH aptasensor clearly distinguished between malaria-positive blood samples of two major species (P. vivax and P. falciparum) and a negative control, indicating that it may be a useful tool for the diagnosis, monitoring, and surveillance of malaria.

A turn-on two-photon fluorescent probe for ATP and ADP

An acedan derivative containing Zn(II)-DPA has been developed as a two-photon probe for nucleoside phosphates, which shows enhanced fluorescence toward ATP and ADP at physiological pH 7.4 among other competing anions including AMP; the probe is permeable to cell membranes and thus can be directly used for two-photon imaging of ATP and ADP in live cells.

Gold nanoparticle-based colorimetric detection of kanamycin using a DNA aptamer

A selective kanamycin-binding single-strand DNA (ssDNA) aptamer (TGGGGGTTGAGGCTAAGCCGA) was discovered through in vitro selection using affinity chromatography with kanamycin-immobilized sepharose beads. The selected aptamer has a high affinity for kanamycin and also for kanamycin derivatives such as kanamycin B and tobramycin. The dissociation constants (K(d) [kanamycin]=78.8 nM, K(d) [kanamycin B]=84.5 nM, and K(d) [tobramycin]=103 nM) of the new aptamer were determined by fluorescence intensity analysis using 5'-fluorescein amidite (FAM) modification. Using this aptamer, kanamycin was detected down to 25 nM by the gold nanoparticle-based colorimetric method. Because the designed colorimetric method is simple, easy, and visible to the naked eye, it has advantages that make it useful for the detection of kanamycin. Furthermore, the selected new aptamer has many potential applications as a bioprobe for the detection of kanamycin, kanamycin B, and tobramycin in pharmaceutical preparations and food products.

Inorganic phosphate induces mammalian growth plate chondrocyte apoptosis in a mitochondrial pathway involving nitric oxide and JNK MAP kinase

Chondrocytes in the hypertrophic zone of the growth plate undergo apoptosis during endochondral bone development via mechanisms that involve inorganic phosphate (Pi) and nitric oxide (NO). Recent evidence suggests that Pi-dependent NO production plays a role in apoptosis of cells in the resting zone as well. This study examined the mechanism by which Pi induces NO production and the signaling pathways by which NO mediates its effects on apoptosis in these cells. Pi decreased the number of viable cells based on MTT activity; the number of TUNEL-positive cells and the level of DNA fragmentation were increased, indicating an increase in apoptosis. Blocking NO production using the NO synthase (NOS) inhibitor L: -NAME or cells from eNOS(-/-) mice blocked Pi-induced chondrocyte apoptosis, indicating that NO production is necessary. NO donors NOC-18 and SNOG both induced chondrocyte apoptosis. SNOG also upregulated p53 expression, the Bax/Bcl-2 expression ratio, and cytochrome c release from mitochondria, as well as caspase-3 activity, indicating that NO induces apoptosis via a mitochondrial pathway. Inhibition of JNK, but not of p38 or ERK1/2, MAP kinase was able to block NO-induced apoptosis, indicating that JNK is necessary in this pathway. Pi elevates NO production via eNOS in resting zone chondrocytes, which leads to a mitochondrial apoptosis pathway dependent on JNK.

Molecular characterization of the human ABO blood group orthologus system in pigs

The selection and use of animals with blood group 0 in the process of transplanting pig organs or tissues into humans can positively contribute to the control of acute immune rejection due to differences in blood groups. Exon-specific PCRs for the porcine blood group A transferase gene against genomic DNA from either blood group A or 0 animals resulted in the amplification failure of the A0 blood group gene exon 8 from blood group 0 animals. To characterize the genetic abnormality in the genome of blood group 0 animals, we screened bacterial artificial chromosome (BAC) clones from a Korean native pig BAC library which had the blood group 0 allele, and carried out shotgun sequencing. The analysis showed that the 0 allele has a large deletion between exon 7 of the A0 blood group gene and the neighbouring SURF6. We also showed that the ABO blood group antigens in humans and the A0 blood group antigens in pigs are coded by mutations within the orthologous glycosyltransferase gene. In addition, we developed a multiplex genotyping method for the porcine A0 blood group gene.

Assessment of referral patterns for CT KUB in a tertiary setting

The purpose of this study was to assess the referral patterns and the use of unenhanced renal tract CT (CT KUB) for investigating patients presenting with clinically suspected renal colic. We retrospectively reviewed 500 consecutive CT KUB studies requested for suspected renal colic carried out at a single institution between December 2006 and July 2007. Follow-up radiology reports and discharge summaries on the hospital clinical Intranet were also reviewed. Studies were analysed for characteristics including patient demographics, referring clinical team, time of referral, final diagnosis and requirement for further imaging. The majority of requests were from Emergency (ED) or Urology Departments (49%, 245 out of 500, and 37%, 186 out of 500, respectively). The positive rate for urolithiasis was 67% (337 out of 500), the negative rate was 25% (123 out of 500), and 8% (40 out of 500) of patients had alternative significant findings. Female patients were more likely to have a negative study than male patients (35 versus 20%, P < 0.0001) and more likely to have alternative significant pathology (12 versus 6%, P < 0.0001). Patients referred by specialities other than Urology and ED were more likely to be female and have a negative or alternative finding (P < 0.0001). CT KUB is a widely used first method of investigation for patients with suspected renal colic with a high positive predictive value allowing rapid diagnosis and intervention. However, given the high rate of negative or alternative findings on CT KUB in young women, especially those referred by specialities other than ED or Urology, ultrasound should be considered as an alternative imaging method to minimise unnecessary radiation exposure.

The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes

OBJECTIVE

To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes.

DESIGN

Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1beta. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1beta-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting.

RESULTS

The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100 micro M of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50 micro M. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10 micro M. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1beta, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50 micro M, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level.

CONCLUSIONS

Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100 micro M of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss.

Endothelial NOS-dependent activation of c-Jun NH(2)- terminal kinase by oxidized low-density lipoprotein

Oxidized low-density lipoprotein (oxLDL) is known to activate a number of signal transduction pathways in endothelial cells. Among these are the c-Jun NH(2)-terminal kinase (JNK), also known as stress-activated protein kinase, and extracellular signal-regulated kinase (ERK). These mitogen-activated protein kinases (MAP kinase) determine cell survival in response to environmental stress. Interestingly, JNK signaling involves redox-sensitive mechanisms and is activated by reactive oxygen and nitrogen species derived from both NADPH oxidases, nitric oxide synthases (NOS), peroxides, and oxidized low-density lipoprotein (oxLDL). The role of endothelial NOS (eNOS) in the activation of JNK in response to oxLDL has not been examined. Herein, we show that on exposure of endothelial cells to oxLDL, both ERK and JNK are activated through independent signal transduction pathways. A key role of eNOS activation through a phosphatidylinositol-3-kinase-dependent mechanism leading to phosphorylation of eNOS is demonstrated for oxLDL-dependent activation of JNK. Moreover, we show that activation of ERK by oxLDL is critical in protection against the cytotoxicity of oxLDL.