High glucose concentration up-regulates the expression of matrix metalloproteinase-9 and -13 in tendon cells

Background

Diabetes mellitus is associated with tendinopathy or tendon injuries. However, the mechanism underlying diabetic tendinopathy is unclear. The purpose of this study was to examine the effects of high glucose concentrations on the activity and expression of matrix metalloproteinases, type I collagen, and type III collagen in tendon cells.

Methods

Tendon cells from rat Achilles tendons were treated with 6 mM, 12 mM, and 25 mM glucose, and then cell proliferation was evaluated by the 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Messenger RNA (mRNA) expression of MMP-2, MMP-8, MMP-9, and MMP-13 and type I and type III collagen was assessed by quantitative real-time polymerase chain reaction (PCR). The enzymatic activity of MMP-2 and MMP-9 was measured by gelatin zymography.

Results

The MTT assay results showed that the glucose concentration did not affect tendon cell proliferation. The results of the real-time PCR assay revealed that the mRNA expression of MMP-9 and MMP-13 was up-regulated by treatment with 25 mM glucose, whereas the mRNA expression of type I and III collagen was not affected. Gelatin zymography showed that 25 mM glucose increased the enzymatic activity of MMP-9.

Conclusions

High glucose concentration up-regulates the expression of MMP-9 and MMP-13 in tendon cells, which may account for the molecular mechanisms underlying diabetic tendinopathy.

Catalytic solid substrate room temperature phosphorimetry for the determination of trace rhamnose based on its condensation reaction with calcein

Calcein (R) could not only emit strong and stable room temperature phosphorescence (RTP) on filter paper using I(-) as perturber, but also could be oxidized by H(2)O(2) to form a non-phosphorescence compound (R'), resulting in the quenching of RTP signal of R. Moreover, the ortho-hydrogen of phenolic hydroxyl in R took condensation reaction with rhamnose (Rha) to produce non-phosphorescence compound (R-Rha) causing the RTP signal of R to further quench, and R-Rha was oxidized by H(2)O(2) to form R' and Rha, bringing about the sharp RTP signal quenching of R. Thus, a new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace Rha based on its strong catalytic effect on H(2)O(2) oxidizing R has been established, with the detection limit (LD) of 7.8zgspot(-1) (corresponding concentration: 2.0×10(-17) gm l(-1), sample volume: 0.40 μl spot(-1)). This method has been applied to determine trace Rha in cigarettes and jujubes, with the results coinciding well with those determined by a high performance liquid chromatography (HPLC). The component of R-Rha also was analyzed by means of HPLC, mass spectrometer and nuclear magnetic resonance (NMR) measurements. The mechanism of catalytic SSRTP for the determination of trace Rha was discussed.

Catalytic solid substrate-room-temperature phosphorimetry detection for trace cadmium with Cd2+ -3.5-generation polyamidoamine dendrimer-Tween-80 complex

3.5-Generation polyamidoamine dendrimers (3.5-G-D) emitted strong and stable room-temperature phosphorescence (RTP) on filter paper when Pb2+ was used as a heavy atom perturber. The RTP signal of 3.5-G-D was sharply enhanced upon the formation of 3.5-G-D-Tween-80 micelle compound. The complex Cd2+ -3.5-G-D-Tween-80, generated in the coordination reaction between Cd2+ and the tertiary amidocyanogen on the outer layer of 3.5-G-D in 3.5-G-D-Tween-80 micelle compound, could catalyze KBrO3 to oxidize 3.5-G-D in 3.5-G-D-Tween-80, which caused the sharp quenching of the RTP signal of the system. The phosphorescence intensity change (ΔI(p) ) of the system had a linear relationship with the content of Cd2+. Thus a new catalytic solid substrate-room-temperature phosphorimetry (SS-RTP) for the determination of trace cadmium has been established. This highly selective and sensitive method has been applied to determine trace cadmium in biological samples with a limit of detection (LD) of 1.2 ag per spot (when the sample volume was 0.4 μL per spot, the corresponding concentration was 3.0 × 10(-15)  g mL(-1) ), the results agreeing with those obtained by atomic absorption spectrometry. The mechanism of catalytic SS-RTP for the determination of trace cadmium was also discussed.

MFTZ-1 reduces constitutive and inducible HIF-1α accumulation and VEGF secretion independent of its topoisomerase II inhibition

The macrolide compound MFTZ-1 has been identified as a novel topoisomerase II (Top2) inhibitor with potent in vitro and in vivo anti-tumour activities. In this study, we further examined the effects of MFTZ-1 on hypoxia-inducible factor-1α (HIF-1α) accumulation, vascular endothelial growth factor (VEGF) secretion and angiogenesis. MFTZ-1 reduced HIF-1α accumulation driven by hypoxia or growth factors in human cancer cells. Mechanistic studies revealed that MFTZ-1 did not affect the degradation of HIF-1α protein or the level of HIF-1α mRNA. By contrast, MFTZ-1 apparently inhibited constitutive and inducible activation of both phosphatidylinositol-3-kinase (PI3K)-Akt and p42/p44 mitogen-activated protein kinase (MAPK) pathways. Further studies revealed that MFTZ-1 abrogated the HIF-1α-driven increase in VEGF mRNA and protein secretion. MFTZ-1 also lowered the basal level of VEGF secretion. The results reveal an important feature that MFTZ-1 can reduce constitutive, HIF-1α-independent VEGF secretion and concurrently antagonize inducible, HIF-1α-dependent VEGF secretion. Moreover, MFTZ-1 disrupted tube formation of human umbilical vein endothelial cells (HUVECs) stimulated by hypoxia with low-concentration serum or by serum at normoxia, and inhibited HUVECs migration at normoxia. MFTZ-1 also prevented microvessel outgrowth from rat aortic ring. These data reflect the potent anti-angiogenesis of MFTZ-1 under different conditions. Furthermore, using specific small interfering RNA targeting Top2α or Top2-defective HL60/MX2 cells, we showed that MFTZ-1 affected HIF-1α accumulation and HUVECs tube formation irrelevant to its Top2 inhibition. Taken together, our data collectively reveal that MFTZ-1 reduces constitutive and inducible HIF-1α accumulation and VEGF secretion possibly via PI3K-Akt and MAPK pathways, eliciting anti-angiogenesis independently of its Top2 inhibition.

Analysis application in biological field and prediction of human diseases with dual luminescence molecular of 3.5-generations polyamidoamine dendrimers-porphyrin

A new phosphorescence-labelling reagent (3.5-G-D-P labelling reagent) was developed, based on 3.5-generation polyamidoamine dendrimers (3.5-G-D) as internal acceptor to capture porphyrin (P) molecular. In the disturber of heavy atom, 3.5-G-D-P could emit room temperature phosphorescence (RTP) of 3.5-G-D and P on the surface of polyamide membrane (PAM), respectively. Products (3.5-G-D-P-WGA) of 3.5-G-D-P labelling triticum vulgaris lectin (WGA) could emit strong and stable RTP signal on the surface of PAM, and it also could take specific affinity adsorption reaction (AA) with alkaline phosphatase (ALP). The product of the AA reaction (3.5-G-D-P-WGA-ALP) could keep the RTP characteristics of 3.5-G-D-P very well, and the DeltaI(p) of the system was linear correlation to the content of ALP. The DeltaI(p) of the system with Tween-80 was once for P and twice for 3.5-G-D more than that without Tween-80. Thus, the affinity adsorption solid substrate-room temperature phosphorimetry (AA-SS-RTP) for the determination of trace ALP has been established using Tween-80-3.5-G-D-P to label WGA. The detection limit (LD) of this method was 0.12fgspot(-1) for 3.5-G-D and 0.18fgspot(-1) for P with direct method, 0.14fgspot(-1) for 3.5-G-D and 0.17fgspot(-1) for P with sandwich method, respectively, and the sensitivity was obviously high. This research showed that either using 3.5-G-D or P excitation/emission wavelength to determine the content of ALP in human serum, the results were coincided with ELISA, and the flexibility of AA-SS-RTP was obviously improved and the applicability was wider. Meanwhile, the reaction mechanism of determining ALP by direct method AA-SS-RTP was discussed.

Determination of trace alkaline phosphatase by affinity adsorption solid substrate room temperature phosphorimetry based on wheat germ agglutinin labeled with 8-quinolineboronic acid phosphorescent molecular switch and prediction of diseases

The 8-quinolineboronic acid phosphorescent molecular switch (abbreviated as PMS-8-QBA. Thereinto, 8-QBA is 8-quinolineboronic acid, and PMS is phosphorescent molecular switch) was found for the first time. PMS-8-QBA, which was in the "off" state, could only emit weak room temperature phosphorescence (RTP) on the acetyl cellulose membrane (ACM). However, PMS-8-QBA turned "on" automatically for its changed structure, causing that the RTP of 8-QBA in the system increased, after PMS-8-QBA-WGA (WGA is wheat germ agglutinin) was formed by reaction between -OH of PMS-8-QBA and -COOH of WGA. More interesting is that the -NH(2) of PMS-8-QBA-WGA could react with the -COOH of alkaline phosphatase (AP) to form the affinity adsorption (AA) product WGA-AP-WGA-8-QBA-PMS (containing -NH-CO- bond), which caused RTP of the system to greatly increase. Thus, affinity adsorption solid substrate room temperature phosphorimetry using PMS-8-QBA as labelling reagent (PMS-8-QBA-AA-SSRTP) for the determination of trace AP was established. The method had many advantages, such as high sensitivity (the detection limit (LD) was 2.5zgspot(-1). For sample volume of 0.40mulspot(-1), corresponding concentration was 6.2x10(-18)gml(-1)), good selectivity (the allowed concentration of coexisting material was higher, when the relative error was +/-5%), high accuracy (applied to detection of AP content in serum samples, the result was coincided with those obtained by enzyme-linked immunoassay), which was suitable for the detection of trace AP content in serum samples and the forecast of human diseases. Meanwhile, the mechanism of PMS-8-QBA-AASSRTP was discussed. The new field of analytical application and clinic diagnosis technique of molecule switch are exploited, based on the phosphorescence characteristic of PMS-8-QBA, the AA reaction between WGA and AP, as well as the relation between AP content and human diseases. The research results promote the development and interpenetrate among molecule switch technique, lectin science and SSRTP.

Determination of trace deoxyribonucleic acid by using fluorescein isothiocyanate-phenosafranine as a double-luminescent phosphorescence probe

Using Pb(2+) as ion perturber, phenosafranine (PF) and fluorescein isothiocyanate (FITC) could emit strong and stable room temperature phosphorescence (RTP) signal on the filter paper, respectively. When they were mixed, the phenomenon that the RTP signal of PF and FITC enhanced significantly was found. And 1.12 ag DNA spot(-1) (sample volume was 0.40 μL, corresponding concentration was 2.8 × 10(-15) g mL(-1)) could cause the RTP signal of both PF and FITC to enhance sharply. The content of DNA was proportional to the ΔI(p) of PF and FITC in the system at 634 and 659 nm. Thus, a new solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace DNA was established by using FITC-PF as double-luminescent phosphorescence probe. The detection limit (LD) of this method calculated by 3S(b)/k was 14 zg DNA spot(-1) for PF and 18 zg DNA spot(-1) for FITC, respectively, showing high sensitivity. It has been applied to the determination of trace DNA in practical samples and the analysis results were in accordance with those of fluorescence probe. The reaction mechanism of SSRTP for the determination of trace DNA was also discussed.

Dihydroartemisinin accelerates c-MYC oncoprotein degradation and induces apoptosis in c-MYC-overexpressing tumor cells

Artemisinin and its derivatives (ARTs) are effective antimalarial drugs and also possess profound anticancer activity. However, the mechanism accounted for its distinctive activity in tumor cells remains unelucidated. We computed Pair wise Pearson correlation coefficients to identify genes that show significant correlation with ARTs activity in NCI-55 cell lines using data obtained from studies with HG-U133A Affymetrix chip. We found c-myc is one of the genes that showed the highest positive correlation coefficients among the probe sets analyzed (r=0.585, P<0.001). Dihydroartemisinin (DHA), the main active metabolite of ARTs, induced significant apoptosis in HL-60 and HCT116 cells that express high levels of c-MYC. Stable knockdown of c-myc abrogated DHA-induced apoptosis in HCT116 cells. Conversely, forced expression of c-myc in NIH3T3 cells sensitized these cells to DHA-induced apoptosis. Interestingly, DHA irreversibly down-regulated the protein level of c-MYC in DHA-sensitive HCT116 cells, which is consistent to persistent G1 phase arrest induced by DHA. Further studies demonstrated that DHA accelerated the degradation of c-MYC protein and this process was blocked by pretreatment with the proteasome inhibitor MG-132 or GSK 3beta inhibitor LiCl in HCT116 cells. Taken together, ARTs might be useful in the treatment of c-MYC-overexpressing tumors. We also suggest that c-MYC may potentially be a biomarker candidate for prediction of the antitumor efficacies of ARTs.

BB, a new EGFR inhibitor, exhibits prominent anti-angiogenesis and antitumor activities

Aberrant activation of the epidermal growth factor receptor (EGFR) is closely associated with malignant progression of tumors. EGFR inhibitors have been used successfully in clinic in the treatment of solid tumors. In the present study, we revealed that BB, a new synthetic quinonazoline derivative, was a potent EGFR inhibitor. BB selectively inhibited EGFR with a IC(50) value of 50 +/- 37 nM, at least 32-fold more potent than suppressed all other ten tested receptor tyrosine kinases including the same family member ErbB2 (IC(50) = 5.6 +/- 3.2 microM). BB effectively abrogated autophosphorylation of the EGF-stimulated EGFR and phosphorylation of its key downstream signaling molecules ERK and AKT in A549 cells. BB was shown to suppress EGF-stimulated proliferation of A549 cells with an apparently lower IC(50) value (0.33 +/- 0.07 microM) than that (2.7 +/- 0.4 microM) for the serum-stimulated cells. BB also inhibited the EGF-independent proliferation of a panel of tumor cells. In addition, BB exhibited anti-angiogenesis activity, as evidenced by antagonizing EGF-induced HMEC-1 migration in vitro, blocking HMEC-1 tube formation, and inhibiting microvessel sprouting from rat aortic rings. Most importantly, BB prominently inhibited in vivo tumorigenesis of NIH3T3 cells specifically driven by the activation-mutated EGFR genes. As reported, normal NIH3T3 cells lack tumorigenicity in nude mice. NIH3T3 cells transfected with the EGFR gene with activating mutation (A750P or L858R) produced rapidly growing xenografts in nude mice. BB, when given orally at 100 mg/kg consecutively for 2 w, prominently inhibited the growth of the xenografts and reduced the number of microvessels. Taken together, the data indicate that BB is a new selective EGFR inhibitor with potent antitumor activity, revealing its potential as a promising anticancer candidate.

Anti-angiogenic and vascular disrupting effects of C9, a new microtubule-depolymerizing agent

BACKGROUND AND PURPOSE

The critical role of blood supply in the growth of solid tumours makes blood vessels an ideal target for anti-tumour drug discovery. The anti-angiogenic and vascular disrupting activities of C9, a newly synthesized microtubule-depolymerizing agent, were investigated with several in vitro and in vivo models. Possible mechanisms involved in its activity were also assessed.

EXPERIMENTAL APPROACH

Microtubule-depolymerizing actions were assessed by surface plasmon resonance binding, competitive inhibition and cytoskeleton immunofluorescence. Anti-angiogenic and vascular disrupting activities were tested on proliferation, migration, tube formation with human umbilical vein endothelial cells, and in rat aortic ring, chick chorioallantoic membrane and Matrigel plug assays. Western blots and Rho activation assays were employed to examine the role of Raf-MEK-ERK (mitogen-activated ERK kinase, extracellular signal-regulated kinase) and Rho/Rho kinase signalling.

KEY RESULTS

C9 inhibited proliferation, migration and tube formation of endothelial cells and inhibited angiogenesis in aortic ring and chick chorioallantoic membrane assays. C9 induced disassembly of microtubules in endothelial cells and down-regulated Raf-MEK-ERK signalling activated by pro-angiogenic factors. In addition, C9 disrupted capillary-like networks and newly formed vessels in vitro and rapidly decreased perfusion of neovasculature in vivo. Endothelial cell contraction and membrane blebbing induced by C9 in neovasculature was dependent on the Rho/Rho kinase pathway.

CONCLUSIONS AND IMPLICATIONS

Anti-angiogenic and vascular disruption by C9 was associated with changes in morphology and function of endothelial cells, involving the Raf-MEK-ERK and Rho/Rho kinase signalling pathways. These findings strongly suggest that C9 is a new microtubule-binding agent that could effectively target tumour vasculature.

Salvicine triggers DNA double-strand breaks and apoptosis by GSH-depletion-driven H2O2 generation and topoisomerase II inhibition

Glutathione (GSH), as the major small-molecule antioxidant in cells, has been implicated in the regulation of cell proliferation and apoptosis. Salvicine (SAL), a novel diterpenoid quinone compound, exhibits potent antitumor activities both in vitro and in vivo by poisoning topoisomerase II (Topo II) and has entered Phase II clinical trials for cancer therapy. Herein, we provide further evidence that SAL-induced DNA double-strand breaks (DSBs) and apoptosis by GSH depletion drives H2O2 generation and Topo II inhibition. Our data reveal that treatment with SAL results in a pronounced increase in intracellular H2O2 and is accompanied by the occurrence of DNA DSBs and apoptosis in epithelial HeLa cells. Furthermore, SAL was also noted to trigger a dramatic depletion of intracellular GSH via its direct reaction with GSH. Importantly, the introduction of GSH and overexpression of catalase antagonized SAL-mediated DNA DSBs and apoptosis, and the GSH synthesis inhibitor dl-buthionine-[S,R]-sulfoximine reduced SAL-mediated H2O2 generation, indicating that SAL-mediated H2O2 generation is derived from intracellular GSH depletion. Notably, SAL-mediated Topo II inhibition was also concentration-dependently reversed by GSH. Furthermore, we found that Topo II-defective HL-60/MX2 cells were almost completely resistant to SAL-induced DNA DSBs, suggesting that, in addition to its direct inhibitory effect on Topo II, SAL-mediated H2O2 generation may also trigger DNA DSBs via poisoning of Topo II. All these findings together suggest that GSH-depletion-driven H2O2 generation and Topo II inhibition are both critical for SAL-induced DNA DSBs and apoptosis.

Naturally occurring homoisoflavonoids function as potent protein tyrosine kinase inhibitors by c-Src-based high-throughput screening

Protein tyrosine kinase (PTK) inhibitors represent emerging therapeutics for cancer chemoprevention. In our study, hematoxylin (26) was identified as one of the most remarkable c-Src inhibitors in an orthogonal compound-mixing library (32200 compounds) by using an ELISA-based automated high-throughput screening (HTS) strategy. Interestingly, hematoxylin was found to be an ATP competitive broad-spectrum PTK inhibitor in vitro, with IC50 values ranging from nanomolar to micromolar level. Further studies showed that such inhibition was associated with the PTK phosphorylation and subsequent downstream signaling pathways. The structure-activity relationship assessment of the PTK inhibitory potency of hematoxylin analogues isolated from Heamatoxylon campechianum was in good agreement with the result of concurrent molecular docking simulation: the catechol moiety in ring A and the hematoxylin-like three-dimensional structure were essential for c-Src-targeted activities. Hematoxylin and its natural analogues were substantially validated to function as a new class of PTK inhibitors.

Cytotoxic sesquiterpenoids from Vernonia bockiana

Two new sesquiterpenoids, vernobockolides A (1) and B (2), along with five known ones, piptocarphin C (3), piptocarphin F (4), piptocarphin A (5), hirsutolide (6), and beta-d-glucopyranosyl taraxinic ester (7), were isolated from the aerial part of Vernonia bockiana. Their structures were determined by spectroscopic analysis, especially 2D NMR. Among them, compounds 2-6 showed strong cytotoxic activities against mouse lymphoid tumor cell line P388 with the IC(50) values of 1.81, 1.32, 0.77, and 0.73 microM, respectively.

ADAM15 suppresses cell motility by driving integrin alpha5beta1 cell surface expression via Erk inactivation

Human ADAM15 is unique among the A disintegrin and metalloprotease domain (ADAM) family because of the integrin binding motif Arg-Gly-Asp (RGD) within its disintegrin domain. Integrin alpha5beta1 has been reported to bind to ADAM15 in an RGD-dependent manner, but the biological significance of the interaction between ADAM15 and alpha5beta1 is unknown. To characterize the effects of ADAM15 on alpha5beta1-mediated cell adhesion and migration and elucidate the potential mechanism, CHO cells which express endogenous integrin alpha5beta1 were transfected with human ADAM15 cDNA. ADAM15 overexpression led to enhanced cell adhesion and decreased migration on fibronectin, which were suppressed by down-regulation of integrin alpha5. Overexpression of ADAM15 not only increased the cell surface expression of integrin alpha5 but also resulted in a more clustered staining of alpha5 on cell surface, while the beta1 subunit remained unchanged. Unexpectedly, results from immunoprecipitation and immunofluorescence indicated that ADAM15 and alpha5beta1 integrin did not interact directly in CHO cells. We found that ADAM15 expression decreased the phosphorylation of Erk1/2. Consistently, down-regulation of Erk1/2 phosphorylation by MEK inhibitor PD98059 or siRNA against Erk1/2 enhanced the expression of alpha5 on cell surface. By using a B16F10 pulmonary metastasis model, we revealed that overexpression of ADAM15 significantly reduced the number of metastatic nodules on the lung. Taken together, this study reveals for the first time that ADAM15 could drive alpha5 integrin expression on cell surface via down-regulation of phosphorylated Erk1/2. This presents a novel mechanism by which ADAM15 regulates cell-matrix adhesion and migration.

Cytotoxic triterpenoid saponins from Vaccaria segetalis

By the guidance of bioassay, one new cytotoxic triterpenoid saponin, 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl] quillaic acid 28-O-beta-D-glucopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-fucopyranosyl-(1-->4)]-beta-D-fucopyranoside (1), and five known cytotoxic triterpenoid saponins, vaccaroside E (2), vaccaroside G (3), vaccaroside B (4), segetoside H (5) and segetoside I (6), were isolated from Vaccaria segetalis. Their structures were established on the basis of ESI-MS, IR, extensive NMR ((1)H NMR, (13)C NMR, TOCSY, (1)H-(1)H COSY, DEPT, HMQC, HMBC and ROESY) analyses, chemical degradation, and by comparing with previously reported data. Compounds 1-6 showed moderate cytotoxic activities against LNcap, P-388 and A-549 cell lines with IC(50) values in the range 0.1-12.9 microM.