Wnt4 and LAP2alpha as pacemakers of Thymic Epithelial Senescence

Age-associated thymic involution has considerable physiological impact by inhibiting de novo T-cell selection. This impaired T-cell production leads to weakened immune responses. Yet the molecular mechanisms of thymic stromal adipose involution are not clear. Age-related alterations also occur in the murine thymus providing an excellent model system. In the present work structural and molecular changes of the murine thymic stroma were investigated during aging. We show that thymic epithelial senescence correlates with significant destruction of epithelial network followed by adipose involution. We also show in purified thymic epithelial cells the age-related down-regulation of Wnt4 (and subsequently FoxN1), and the prominent increase in LAP2α expression. These senescence-related changes of gene expression are strikingly similar to those observed during mesenchymal to pre-adipocyte differentiation of fibroblast cells suggesting similar molecular background in epithelial cells. For molecular level proof-of-principle stable LAP2α and Wnt4-over-expressing thymic epithelial cell lines were established. LAP2α over-expression provoked a surge of PPARγ expression, a transcription factor expressed in pre-adipocytes. In contrast, additional Wnt4 decreased the mRNA level of ADRP, a target gene of PPARγ. Murine embryonic thymic lobes have also been transfected with LAP2α- or Wnt4-encoding lentiviral vectors. As expected LAP2α over-expression increased, while additional Wnt4 secretion suppressed PPARγ expression. Based on these pioneer experiments we propose that decreased Wnt activity and increased LAP2α expression provide the molecular basis during thymic senescence. We suggest that these molecular changes trigger thymic epithelial senescence accompanied by adipose involution. This process may either occur directly where epithelium can trans-differentiate into pre-adipocytes; or indirectly where first epithelial to mesenchymal transition (EMT) occurs followed by subsequent pre-adipocyte differentiation. The latter version fits better with literature data and is supported by the observed histological and molecular level changes

AMPLITUDE DEPENDENT BETATRON OSCILLATION CENTER SHIFT BY NON-LINEARITY AND BEAM INSTABILITY INTERLOCK

Abstract As a result of the even symmetry of the Sextupole field, it creates the horizontal shift of the averaged position of horizontal and vertical betatron oscillation and the amount of the shift depends on its oscillation amplitude. This shift can be observed with usual slow orbit beam position monitor. At the SPring-8 storage ring, this shift is used to detect the excitation of the betatron oscillation for the interlock system for the protection of the vacuum components from strong radiation of insertion devices. AMPLITUDE DEPENDENT BETATRON OSCILLATION CENTER SHIFT The transverse beam instability drives a horizontal or vertical betatron oscillation, and if this occurs in light sources, the strong synchrotron radiation from insertion devices also oscillates as the beam and cause heat damages on beam pipe components if the radiation continuously hit them. The even symmetry of the sextupole field produces the horizontal shift of the time averaged horizontal position if the horizontal and vertical betatron oscillation exists. Here we call it an amplitude dependent betatron oscillation center shift (ADCS). The ADCS on the sextupole strength can be derived by a canonical perturbation theory as the first order effect by sextupole field [1] as where the symbols with overline are the time averaged values, J z and φ z ( z = x, y ) are the action and the phase, respectively, and related to the position and beta function β z s The sextupole strength is expressed as for the magnetic field

Challenge and promise: the role of miRNA for pathogenesis and progression of malignant melanoma

microRNAs are endogenous noncoding RNAs that are implicated in gene regulation. More recently, miRNAs have been shown to play a pivotal role in multiple cellular processes that interfere with tumorigenesis. Here we summarize the essential role of microRNAs for human cancer with special focus on malignant melanoma and the promising perspectives for cancer therapies

Slug expression is an independent prognostic parameter for poor survival in colorectal carcinoma patients

Slug, a member of the Snail family of transcription factors, plays a crucial role in the regulation of epithelial-mesenchymal transition (EMT) by suppressing several epithelial markers and adhesion molecules including E-cadherin. Recently, several studies have reported Slug to be expressed in breast carcinoma, oesophageal carcinoma accompanied with shorter survival. In this study, we first investigated expression of Slug mRNA in five colorectal carcinoma cell lines by reverse transcription–polymerase chain reaction. Furthermore, we investigated Slug and E-cadherin expression by immunohistochemistry in 138 patients with colorectal carcinoma. Slug mRNA was clearly expressed in four out of five colorectal carcinoma cell lines. Positive expression of Slug and E-cadherin was observed in 37 and 58% of cases, respectively. The positive expression of Slug was significantly associated with Dukes stage and distant metastasis (P=0.0027 and 0.0007), and the positive expression of Slug had a significant impact on patient overall survival (P<0.0001, log-rank test). Moreover, patients with positive expression of Slug and reduced expression of E-cadherin showed the worst prognosis (P<0.0001, log-rank test). Multivariate analysis indicated that Slug expression was an independent prognostic factor. These results suggest that positive Slug expression in colorectal carcinoma patients may become a significant parameter of poor prognosis

Interaction between lung cancer cells and astrocytes via specific inflammatory cytokines in the microenvironment of brain metastasis

The incidence of brain metastasis is increasing, however, little is known about molecular mechanism responsible for lung cancer-derived brain metastasis and their development in the brain. In the present study, brain pathology was examined in an experimental model system of brain metastasis as well as in human brain with lung cancer metastasis. In an experimental model, after 3–6 weeks of intracardiac inoculation of human lung cancer-derived (HARA-B) cells in nude mice, wide range of brain metastases were observed. The brain sections showed significant increase in glial fibrillary acidic protein (GFAP)-positive astrocytes around metastatic lesions. To elucidate the role of astrocytes in lung cancer proliferation, the interaction between primary cultured mouse astrocytes and HARA-B cells was analyzed in vitro. Co-cultures and insert-cultures demonstrated that astrocytes were activated by tumor cell-oriented factors; macrophage migration inhibitory factor (MIF), interleukin-8 (IL-8) and plasminogen activator inhibitor-1 (PAI-1). Activated astrocytes produced interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-1 β (IL-1β), which in turn promoted tumor cell proliferation. Semi-quantitative immunocytochemistry showed that increased expression of receptors for IL-6 and its subunits gp130 on HARA-B cells. Receptors for TNF-α and IL-1β were also detected on HARA-B cells but down-regulated after co-culture with astrocytes. Insert-culture with astrocytes also stimulated the proliferation of other lung cancer-derived cell lines (PC-9, QG56, and EBC-1). These results suggest that tumor cells and astrocytes stimulate each other and these mutual relationships may be important to understand how lung cancer cells metastasize and develop in the brain

Gefitinib (IRESSA) sensitive lung cancer cell lines show phosphorylation of Akt without ligand stimulation

BACKGROUND: Phase III trials evaluating the efficacy of gefitinib (IRESSA) in non-small cell lung cancer (NSCLC) lend support to the need for improved patient selection in terms of gefitinib use. Mutation of the epidermal growth factor receptor (EGFR) gene is reported to be associated with clinical responsiveness to gefitinib. However, gefitinib-sensitive and prolonged stable-disease-defined tumors without EGFR gene mutation have also been reported. METHODS: To identify other key factors involved in gefitinib sensitivity, we analyzed the protein expression of molecules within the EGFR family, PI3K-Akt and Ras/MEK/Erk pathways and examined the sensitivity to gefitinib using the MTT cell proliferation assay in 23 lung cancer cell lines. RESULTS: We identified one highly sensitive cell line (PC9), eight cell lines displaying intermediate-sensitivity, and 14 resistant cell lines. Only PC9 and PC14 (intermediate-sensitivity) displayed an EGFR gene mutation including amplification. Eight out of the nine cell lines showing sensitivity had Akt phosphorylation without ligand stimulation, while only three out of the 14 resistant lines displayed this characteristic (P = 0.0059). Furthermore, the ratio of phosphor-Akt/total Akt in sensitive cells was higher than that observed in resistant cells (P = 0.0016). Akt phosphorylation was partially inhibited by gefitinib in all sensitive cell lines. CONCLUSION: These results suggest that Akt phosphorylation without ligand stimulation may play a key signaling role in gefitinib sensitivity, especially intermediate-sensitivity. In addition, expression analyses of the EGFR family, EGFR gene mutation, and FISH (fluorescence in situ hybridization) analyses showed that the phosphorylated state of EGFR and Akt might be a useful clinical marker of Akt activation without ligand stimulation, in addition to EGFR gene mutation and amplification, particularly in adenocarcinomas

High tie versus low tie of the inferior mesenteric artery: a protocol for a systematic review

In anterior resection of rectum, the section level of inferior mesenteric artery is still subject of controversy between the advocates of high and low tie. The low tie is the division and ligation to the branching of the left colic artery and the high tie is the division and ligation at its origin at the aorta. We intend to assess current scientific evidence in literature and to establish the differences comparing technique, anatomy and physiology. The aim of this protocol is to achieve a meta-analysis that tests safety and feasibility of the two procedures with several types of outcome measures