The Pseudomonas aeruginosa quorum-sensing signal N-(3-oxododecanoyl) homoserine lactone can accelerate cutaneous wound healing through myofibroblast differentiation in rats

Quorum sensing is a cell density-dependent gene regulation system in bacteria. N-(3-oxododecanoyl) homoserine lactone (3-oxo-C12-HSL) is used in the las quorum-sensing system in Pseudomonas aeruginosa, which is an opportunistic pathogen that causes many human diseases. Although many studies have investigated the sole effects of quorum sensing on several types of mammalian cells, including lung cells, little is known about the effects of quorum sensing on the cells associated with wound healing. To better understand the mechanism of bacterial wound infection, we investigated the effects of 3-oxo-C12-HSL on cells using a rat full-thickness wound-healing model. We found that the wound contraction was significantly increased at 24 h after the administration of 3-oxo-C12-HSL to the surface of granulation tissue. Differentiation of fibroblasts to myofibroblasts was induced in the in vivo wound-healing model and was confirmed in vitro using the rat fibroblastic cell line Rat-1. Cyclooxygenase (Cox)-2 expression was also induced in Rat-1 cells by 3-oxo-C12-HSL. This finding suggested that Cox-2 upregulation may be related to the inflammatory findings in the histological examinations, in which infiltrating polymorphonuclear neutrophils were observed at the wound site. Taken together, these results imply that mammals have a potential defense system against invading pathogens by responding to the presence of 3-oxo-C12-HSL and inducing the differentiation of fibroblasts to myofibroblasts as well as inflammation for accelerating wound healing.

Aging-like skin changes induced by ultraviolet irradiation in an animal model of metabolic syndrome

Both physiological skin aging and pathologic photo-aging caused by ultraviolet (UV) irradiation are mediated by latent inflammation and oxidative stress. Although numerous animal skin-aging models have used UV irradiation, most require massive doses or long-term irradiation. To establish a more refined skin-aging model, we focused on an animal model of metabolic syndrome (MS) because MS involves damage to various organs via oxidative stress or inflammation, similar to the changes associated with aging. We hypothesized that MS skin might exhibit more aging-like changes after milder, shorter-term UV irradiation than would normal animal skin under similar conditions, thus providing a useful model for skin aging. The authors therefore examined the skin from Tsumura Suzuki obese diabetic (TSOD) mice (MS model) and control Tsumura Suzuki non-obese (TSNO) mice before and after UV irradiation. Skin from TSOD mice had a thinner epidermis and dermis, a thicker fatty layer, reduced density and convolution of the fragmented collagen fibers, and upregulated expression of tumor necrosis factor (TNF)-α, a dual marker for inflammation and aging, compared to the skin from TSNO mice. UV irradiation affected TSOD skin more severely than TSNO skin, resulting in various changes resembling those in aged human skin, including damage to the dermis and subcutaneous fatty tissue, infiltration of inflammatory cells, and further upregulation of TNF-α expression. These results suggest that UV-irradiated TSOD mice may provide a new model of skin aging and imply that skin from humans with MS is more susceptible to UV- or aging-related damage than normal human skin.

Visible Electroluminescence from Pn Junction Type μc-Sic/ Porous Si / c-Si Structures

We have fabricated two kinds of n-type microcrystalline silicon carbon (μc-SiC) / porous silicon (PS) / p-type crystalline silicon (c-Si) pn junctions and demonstrated a visible light emission from them. We have observed three types of visible light emission; an uniform red light emission at a forward current above 12mA/cm2 for the pn junction using a 0.2–0.4 Qcm c-Si substrate, and a very weak white light emission at a forward current of about 90 mA/mm2 and a strong orange-red light emission at a forward current from 200 to 619 mA/mm2for the pn junction using a 3.5–4.5 Ωcm c-Si substrate.

A possible animal model for critical colonisation

OBJECTIVE

To develop a critical colonisation model in rats that will facilitate investigation of its pathophysiology and the development of new and effective diagnosis and treatment protocols.

METHOD

Three groups of rats were given full-thickness dorsal wounds: a control group received phosphate-buffered saline; an experimental group was inoculated with Pseudomonas aeruginosa; an infection group with streptozotocin-induced diabetes was also inoculated with P. aeruginosa. All groups were assessed on a number of parameters at days 1, 3, 5 and 7 following wounding. Parameters included gross observations, histopathological observations, quantification of redness and swelling, serum C-reactive protein (CRP) measurement and tissue bacterial counts.

RESULTS

Healing was delayed in the experimental group when compared with the control group, with no signs of inflammation. Although the numbers of bacteria were similar in the experimental and infection groups, polymorphonuclear neutrophil (PMN) infiltration was localised to granulation tissue in the experimental group, whereas it extended to muscular tissue in the experimental group. CRP levels remained low in the experimental group.

CONCLUSION

These findings suggest that the inoculation of bacteria provides a possible model of critical colonisation in rats. We believe this will contribute to a better understanding of critical colonisation.

High-efficiency genetic transformation of maize by a mixture of pollen and exogenous DNA

High-efficiency genetic transformation was induced in a genetic stock of maize, Zea mays Linnaeus, by self-pollination of the recipient plants along with DNA of the donor. The highest frequency of transformed endosperm per ear was 9.29%. DNA was applied onto silks in a pollen/DNA pasty mixture. The exogenous DNA transferred into endosperm expressed itself in endosperm formation. It is not known, however, whether the exogenous DNA segment in endosperm had been incorporated or whether it was present in the nucleus additionally, fragmentally, or in some other state. It was revealed that all of four possible cases had occurred as follows: exogenous DNA was transferred into (i) both embryo and endosperm of the same kernel, (ii) embryo only, (iii) endosperm only, and (iv) neither embryo nor endosperm. It was also revealed that exogenous DNA that had entered into the embryo had been maintained through embryo formation, germination, vegetative growth and differentiation, and reproductive growth, and finally was manifested in embryo and/or endosperm of the following generation and acted in endosperm formation. The frequency of transformed endosperm in this generation, however, was rather low. It may be that exogenous DNA taken into the embryo was unstable.

Development of a method to control the water evaporation of hatching eggs during incubation

Three experiments were conducted to develop methods to control the amount of water loss and to evaluate the metabolic effects of water condition in the White Leghorn breeder eggs during incubation. One hundred twenty, 54, and 90 Julia strain White Leghorn breeder eggs were incubated at 37.8 degrees C, 60% RH in experiments 1, 2, and 3. In experiment 1, eggs were drilled with various bore diameters of 0, 0.5, 1, 2, 3, 4, and 5 mm on the blunt end of the eggshell. In experiment 2, 4 x 4 mm(2) windows were cut into the eggs or the eggs were drilled with 5 holes of bore diameter 2 mm on the blunt end of eggshell. In experiment 3, eggs were drilled with 1, 3, 5, and 7 holes of diameter 2 mm on the blunt end of eggshell. Eggs were treated on d 3 of each experiment and the amount of water loss was recorded on d 19 of incubation. Embryo growth was evaluated in experiments 2 and 3. In addition, the livers of embryos were collected in the 0-, 1-, 3-, and 5-hole treatment groups after weighing eggs to determine 3-hydroxy acyl coenzyme A dehydrogenase activity. In experiment 1, although higher water loss was observed in all windowed eggs than in control, there were no differences in amount of water loss among all bore diameters. Accordingly, that was not successful to control amount of water loss. In experiment 2, higher water loss was observed in drilled eggs at the same levels in windowed eggs as in control. Drilling holes was a more useful treatment to control amount of water loss on incubated eggs than windowing. In experiment 3, amount of water loss increased linearly with increasing number of holes on the blunt end of eggshell. Hepatic 3-hydroxy acyl coenzyme A dehydrogenase activity increased with increasing the number of drilled holes.

Repeated recurrence of gastric mucosal lesions in rats after a single treatment with compound 48/80, a mast cell degranulator

We examined the recurrence of gastric mucosal lesions in rats after a single treatment with compound 48/80 (C48/80), a mast cell degranulator. During the period of 0.5 h to 24 h after treatment with C 48/80 (0.75 mg/kg, i.p.), an apparent recurrence of gastric mucosal lesions was found 18 and 24 h after the lesion formation, progression, and recovery occurred during the period of 12 h. Gastric mucosal blood flow showed the maximum reduction at 0.5, 16, and 22 h after treatment followed by the maximum recovery of the decrease at 12, 20, and 24 h, respectively. Gastric mucosal myeloperoxide and xanthine oxidase activities and lipid peroxide content showed the maximum increase at 3, 18, and 24 h after treatment. Gastric mucosal superoxide dismutase activity unchanged after treatment and gastric mucosal catalase activity decreased only at 24 h. Gastric mucosal Se-glutathione peroxidase activity and vitamin E, ascorbic acid, and hexosamine contents showed their maximum decrease at 3, 18, and 24 h after treatment. Gastric mucosal non-protein SH content showed the maximum decrease at 0.5, 16, and 22 h after treatment. Serum histamine and serotonin concentrations increased rapidly after treatment but the increases in serum histamine and serotonin concentrations diminished completely until 12 and 14 h, respectively. These results indicate that lesions recur repeatedly accompanied with an ischemia-reperfusion-like change in blood flow, inflammation, and disruption of antioxidant defense systems in the gastric mucosa of rats in no relation to released histamine and serotonin after a single C48/80 treatment.

Potential contributions of heat shock proteins to temperature-dependent sex determination in the American alligator

Sex determination in the American alligator depends on the incubation temperature experienced during a thermo-sensitive period (TSP), although sex determination can be 'reversed' by embryonic exposure to an estrogenic compound. Thus, temperature and estrogenic signals play essential roles during temperature-dependent sex determination (TSD). The genetic basis for TSD is poorly understood, although previous studies observed that many of the genes associated with genetic sex determination (GSD) are expressed in species with TSD. Heat shock proteins (HSPs), good candidates because of their temperature-sensitive expression, have not been examined in regard to TSD but HSPs have the ability to modify steroid receptor function. A number of HSP cDNAs (HSP27, DNAJ, HSP40, HSP47, HSP60, HSP70A, HSP70B, HSP70C, HSP75, HSP90alpha, HSP90beta, and HSP108) as well as cold-inducible RNA binding protein (CIRBP) and HSP-binding protein (HSPBP) were cloned, and expression of their mRNA in the gonadal-adrenal-mesonephros complex (GAM) was investigated. Embryonic and neonatal GAMs exhibited mRNA for all of the HSPs examined during and after the TSP. One-month-old GAMs were separated into 3 portions (gonad, adrenal gland, and mesonephros), and sexual dimorphism in the mRNA expression of gonadal HSP27 (male > female), gonadal HSP70A (male < female), and adrenal HSP90 alpha (male > female) was observed. These findings provide new insights on TSD and suggest that further studies examining the role of HSPs during gonadal development are needed.

Increased insulin demand promotes while pioglitazone prevents pancreatic beta cell apoptosis in Wfs1 knockout mice

AIMS/HYPOTHESIS

The WFS1 gene encodes an endoplasmic reticulum (ER) membrane-embedded protein called Wolfram syndrome 1 protein, homozygous mutations of which cause selective beta cell loss in humans. The function(s) of this protein and the mechanism by which the mutations of this gene cause beta cell death are still not fully understood. We hypothesised that increased insulin demand as a result of obesity/insulin resistance causes ER stress in pancreatic beta cells, thereby promoting beta cell death.

METHODS

We studied the effect of breeding Wfs1 ( -/- ) mice on a C57BL/6J background with mild obesity and insulin resistance, by introducing the agouti lethal yellow mutation (A ( y ) /a). We also treated the mice with pioglitazone.

RESULTS

Wfs1 ( -/- ) mice bred on a C57BL/6J background rarely develop overt diabetes by 24 weeks of age, showing only mild beta cell loss. However, Wfs1 ( -/- ) A ( y ) /a mice developed selective beta cell loss and severe insulin-deficient diabetes as early as 8 weeks. This beta cell loss was due to apoptosis. In Wfs1 ( +/+ ) A ( y ) /a islets, levels of ER chaperone immunoglobulin-binding protein (BiP)/78 kDa glucose-regulated protein (GRP78) and phosphorylation of eukaryotic translation initiation factor 2, subunit alpha (eIF2alpha) apparently increased. Levels of both were further increased in Wfs1 ( -/- ) A ( y ) /a murine islets. Electron micrography revealed markedly dilated ERs in Wfs1 (-/-) A ( y ) /a murine beta cells. Interestingly, pioglitazone treatment protected beta cells from apoptosis and almost completely prevented diabetes development.

CONCLUSIONS/INTERPRETATION

Wfs1-deficient beta cells are susceptible to ER stress. Increased insulin demand prompts apoptosis in such cells in vivo. Pioglitazone, remarkably, suppresses this process and prevents diabetes. As common WFS1 gene variants have recently been shown to confer a risk of type 2 diabetes, our findings may be relevant to the gradual but progressive loss of beta cells in type 2 diabetes.

HER2 and HER3 cooperatively regulate tumor cell growth and determine sensitivity to the HER kinase inhibitor TAK-285

Abstract #3155

Background: The HER (ErbB) receptor family plays a major role in the proliferation of tumor cells. Overexpression of these receptors occurs in breast and a variety of cancers and correlates with poor prognosis. We have identified TAK-285, a potent, selective and orally bioavailable small molecule inhibitor of HER kinases. TAK-285, which is currently in clinical trials for the treatment of solid tumors, inhibits EGFR (also known as ErbB1 or HER1) and HER2 (also known as ErbB2) and exerts clear anti-proliferative activity in in vitro and in vivo tumor models. Here, we elucidated the determinants of TAK-285 anti-tumor activity in vitro in a panel of human cancer cell lines.&#x2028; Methods: Cell growth inhibition assay was performed using sulforodamine B staining method or CellTiter-GloTM assay (Promega). Candidate gene expressions were measured by quantitative PCR. Associations between the IC50 values and the candidate gene expressions were statistically analysed.&#x2028; Results: TAK-285 exerted anti-proliferative effects in all of cell lines tested in a dose dependent manner but the effects ranged widely (IC50: 0.011-over 10 µmol/L). Statistical analysis showed an inverse correlation between sensitivity to TAK-285 (IC50 values) and HER2 or HER3 (also known as ErbB3) gene expression. PTEN or IGF-1R gene expression, reported to be involved in trastuzumab resistance, was not correlated with TAK-285 sensitivity. Immunoblot analysis revealed that HER2 and HER3 are coexpressed in most TAK-285 sensitive cells and TAK-285 inhibited phosphorylation of HER3. Because HER3 does not possess kinase activity, this suggests that HER3 is trans-phosphorylated by HER2. Knockdown of HER3 using siRNA inhibited tumor cell growth in TAK-285 sensitive cells but not in TAK-285 insensitive cells.&#x2028; Conclusion: These results suggest that HER2 and HER3 mainly regulate tumor cell growth in TAK-285 sensitive cells and could be used as a molecular marker to select patients who are likely to respond to TAK-285.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3155.

A novel HER2 inhibitor TAK-285 overcomes trastuzumab resistance of HER2-over-expressing breast cancer

Abstract #3143

Background: The anti-HER2 antibody trastuzumab has been proven highly effective in the treatment of HER2-expressing breast cancers clinically. However, the continuous administration often leads to drug resistance, the mechanism of which is not well understood. Here we present a new mechanism for trastuzumab-resistance. We also show TAK-285, a novel small molecule HER2/EGFR kinase inhibitor under clinical evaluation, overcomes the resistance to trastuzumab.&#x2028; Methods: A trastuzumab-resistant sub-clone (BT-474TR) of the HER2-positive human breast cancer line, BT-474, was established in house by serial passage in the presence of 5 μg/mL trastuzumab for over 5 months. Gene expression profiles of the clones were assessed using Affymetrix HG-U133 plus 2.0 human gene arrays and confirmed by real-time PCR. Target genes were depleted by siRNA-mediated knockdown and confirmed by real time-PCR and immunoblot. Effects on cell growth were assessed by the CellTiter-Glo luminescent cell viability assay (Promega).&#x2028; Results: BT-474TR cells exhibited modified expression of several genes including cofilin, compared to the parental BT-474 cells. Although immunoblotting using anti-cofilin antibody revealed no clear change in protein level, BT-474TR displayed significant increase in phosphorylation of cofilin. Gene-specific knockdown of cofilin-1 led to re-sensitization of BT-474TR to trastuzumab, though the cofilin-2 knockdown did not. Likewise, knockdown of either LIMK1 or PAK1, known to regulate cofilin-phosphorylation, resulted in similar re-sensitization of BT-474TR to trastuzumab. BT-474TR also exhibited increase in phosphorylation of both LIMK1 and PAK1. TAK-285 showed almost equivalent inhibitory activity against both BT-474 and BT-474TR proliferation in cell culture and in xenograft study, while trastuzumab did not affect the proliferation of BT-474TR in either condition&#x2028; Conclusions: These data suggest that activation of cofilin signaling pathway is a probable mechanism of trastuzumab resistance. PAK1/LIMK1/cofilin-1 inhibitors might therefore be useful in preventing or reversing trastuzumab resistance. The phosphorylation status of PAK1/LIMK1/cofilin might also serve as a biomarker of Trastuzumab-sensitivity. Moreover a novel HER2 inhibitor, TAK-285, might show benefit in the treatment of trastuzumab-resistant HER2-expressing breast cancers.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3143.