Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown MnBi2Te4 thin films.

The intrinsic magnetic topological insulator MnBi2Te4 provides a feasible pathway to the high-temperature quantum anomalous Hall (QAH) effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4 thin flakes, it remains a big challenge to achieve molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4 thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4 and to find a way out of the big difficulty in obtaining MnBi2Te4 samples showing quantized transport properties.

Circulating fibrocytes are involved in inflammation and leukocyte trafficking in neonates with necrotizing enterocolitis.

Fibrocytes, ahematopoietic stem cell source of fibroblasts/myofibroblasts, were previously implicated to infiltrate into the intestinal and enhance inflammation.The aims of the present study were to elucidate the role of fibrocytes in necrotizing enterocolitis (NEC) pathogenesis and to explore the mechanisms by which fibrocytes contributed to the inflammatory responses.We investigated circulating and intestinal local fibrocytes from 32 patients with NEC, 8 patients with noninflammatory conditions of the gastrointestinal tract and 12 normal subjects.Significantly higher numbers of circulating fibrocytes were found in the peripheral blood from NEC patients than the controls (P < .01). Numerous fibrocytes were found infiltrating the NEC intestinal mucous membranes. The percentage of fibrocytes to total leukocytes in the NEC inflammatory lesions was significantly increased compared with the percentage in the noninflammatory gastrointestinal tract. The fibrocyte attractant chemokine C-X-C motif chemokine ligand 12 (CXCL12) was significantly increased in the plasma and was detectable in 80% of the peritoneal lavage fluid from NEC patients but not the controls. Furthermore, chemokine expression was increased in fibrocytes infiltrating and trafficking to leukocyte sites. In culture, lipopolysaccharide (LPS) induced a significant increase in the expression of the Toll-like receptor (TLR4) signal, with the upregulation of p38 in both the isolated fibrocytes and macrophages. Similarly, interleukin (IL)-1ß induced increased the upregulation of the IL-6, tumor necrosis factor (TNF)-α, and intercellular cell adhesion molecule-1 mRNAs but downregulated ColI in fibrocytes isolated from NEC patients compared with the controls.These findings indicate that circulating fibrocytes are increased in NEC patients and may be recruited to the inflammatory intestinal track, most likely through the CXCR4/CXCL12 axis. These cells may contribute to intestinal inflammation through TLR4 signaling by producing the TNF-α and IL-6 cytokines.

Fecal microbiota transplantation (FMT) could reverse the severity of experimental necrotizing enterocolitis (NEC) via oxidative stress modulation.

Fecal microbiota transplantation (FMT) has been used successfully to treat a variety of gastroenterological diseases. The alterations of microbiota in mouse models of necrotizing enterocolitis (NEC) as well as in patients suggested the possibility of treating NEC with FMT. Here we show that FMT caused an improvement in the histopathology and symptoms of NEC in WT mice, but not Grx1-/- mice. FMT eliminated O2•- production and promoted NO production in experimental NEC mice though the modulation of S-glutathionylation of eNOS (eNOS-SSG). FMT decreased the extent of TLR4-mediated proinflammatory signaling though TLR9 in the intestinal mucosa tissue. FMT also suppressed intestinal apoptosis and bacterial translocation across the intestinal barrier, which was accompanied by decreased inflammatory cytokine levels, altered bacterial microbiota, and regulated lymphocyte proportions. FMT is effective in a mouse model of NEC through the modulation of oxidative stress and reduced colon inflammation.

Mitochondrial ATF2 translocation contributes to apoptosis induction and BRAF inhibitor resistance in melanoma through the interaction of Bim with VDAC1.

BACKGROUND: The mitochondrial accumulation of ATF2 is involved in tumor suppressor activities via cytochrome c release in melanoma cells. However, the signaling pathways that connect mitochondrial ATF2 accumulation and cytochrome c release are not well documented. METHODS: Several melanoma cell lines, B16F10, K1735M2, A375 and A375-R1, were treated with paclitaxel and vemurafenib to test the function of mitochondrial ATF2 and its connection to Bim and voltage-dependent anion channel 1 (VDAC1). Immunoprecipitation analysis was performed to investigate the functional interaction between the involved proteins. VDAC1 oligomerization was evaluated using an EGS-based crosslinking assay. RESULTS: The expression and migration of ATF2 to the mitochondria accounted for paclitaxel stimuli and acquired resistance to BRAF inhibitors. Mitochondrial ATF2 facilitated Bim stabilization through the inhibition of its degradation by the proteasome, thereby promoting cytochrome c release and inducing apoptosis in B16F10 and A375 cells. Studies using B16F10 and A375 cells genetically modified for ATF2 indicated that mitochondrial ATF2 was able to dissociate Bim from the Mcl-1/Bim complex to trigger VDAC1 oligomerization. Immunoprecipitation analysis revealed that Bim interacts with VDAC1, and this interaction was remarkably enhanced during apoptosis. CONCLUSION: These results reveal that mitochondrial ATF2 is associated with the induction of apoptosis and BRAF inhibitor resistance through Bim activation, which might suggest potential novel therapies for the targeted induction of apoptosis in melanoma therapy.

[The role of thyroid transcription factor-1 DNA binding activity in lung cancer.].

BACKGROUND: TTF-1 is a homeodomain transcriptional regulator of both structural organization of the lung and differentiation of highly specialized epithelial cell types such as alveolar typeII cells. This study is to investigate the Thyroid transcription factor-1 (TTF-1) DNA binding activity in lung cancer tissue and its significance with lung cancer pathologic type and differentiation level. METHODS: The TTF-1 DNA binding activity was detected in lung cancer tissue by Electrophoretic mobility shift assay (EMSA), autoradiography and photo densitometry. RESULTS: The optical density of TTF-1 DNA binding activity in adenocarcinoma tissue was 172+/-23.2 and it was remarkably higher than that in other pathological types, including 141+/-16.3 of small cell carcinomas and 122+/-13.6 of squamous carcinoma (P <0.05). The optical density of TTF-1 DNA binding activity in highly differentiated lung cancer tissues was significantly higher than that in poor-differentiated lung cancer (P <0.05). Overall survival and disease-free survival rates were better among patients with low TTF-1 DNA binding activity levels than those in patients with high levels. CONCLUSIONS: TTF-1 DNA binding activity is a potential predictor of lung cancer metastasis and survival.

Potential biomarkers involving IKK/RelA signal in early stage non-small cell lung cancer.

The clinical relevance of nuclear factor kappaB (NF-kappaB) and its regulatory molecules on prognosis of patient with early stages of non-small cell lung cancer (NSCLC), remains unclear. Therefore, we conducted biomarker analyses with survival in patients with stages I and II NSCLC. Tumor samples were collected from 88 patients with early-stage NSCLC (stages I, II). A minimum follow-up period of 5 years was required. RelA, phosphorylated I kappaB (pI kappaB alpha), pIKK alpha/beta were detected by immunostaining. NF-kappaB DNA binding activity was assessed by electrophoretic mobility shift assay. Association of clinical and pathologic variables (e.g. sex, age, pathologic stage) with relevant molecules was determined by Pearson's chi(2) test or Fisher's exact test. Survival analysis based on single expression of RelA, pI kappaB alpha, pIKK alpha/beta as well as composite expressions were evaluated using Cox proportional hazards regression models, and log rank test followed Kaplan-Meier estimates. RelA, pI kappaB alpha, pIKK alpha/beta were observed as increased expression in NSCLC tissues compared with adjacent normal tissues and normal lung tissues. These molecules were associated with tumor-node-metastasis stages, T stages and histological status, respectively. Among the molecules analyzed, RelA and pI kappaB alpha-positive were statistically significant predictors of patient death in the entire patient population adjusted by age, gender and smoking status; furthermore both RelA and pI kappaB alpha-positive was the strongest prognostic indicators of poor prognosis by univariate and multivariate analyses. Borderline positive correlations were observed between RelA and pI kappaB alpha or pIKK alpha/beta expression. In this cohort of early-stage NSCLC patients, molecular markers, especially composite application of multiple biomarkers (both nuclear RelA and cytoplasmic pI kappaB-alpha expression) that independently predict overall survival have been identified.

Combined prognostic value of both RelA and IkappaB-alpha expression in human non-small cell lung cancer.

BACKGROUND: We sought to investigate the prognostic significance of nuclear factor (NF)-kappaB activity, especially nuclear RelA and IkappaB-alpha expression patterns, in non-small cell lung cancer (NSCLC). METHODS: A total of 116 patients with pathologically confirmed stage I to II NSCLC were included. Immunohistochemical analysis and electrophoretic mobility shift assays of NF-kappaB were performed to determine RelA and phosphorylated IkappaB-alpha staining, and DNA binding activity of NF-kappaB in human NSCLC. Downstream genes, including VEGF and IL-8, were also assessed. The prognostic significance of a single expression of RelA, phosphorylated IkappaB-alpha, and b-composite expressions was evaluated by Cox proportional hazard regression models and by Kaplan-Meier survival analyses. Correlation between RelA/IkappaB-alpha expression status and clinicopathological features of NSCLC was also analyzed. RESULTS: NF-kappaB DNA binding activity, VEGF, and IL-8 showed correlation with nuclear RelA and cytoplasmic pIkappaB-alpha expression. Expression of nuclear RelA/NF-kappaB showed an increase in NSCLC tissue compared with adjacent normal tissue and normal lung tissue. There was a positive correlation between NF-kappaB activation (nuclear translocation of RelA) and tumor clinicopathological features such as tumor grade, including T stages, N stages, and tumor, node, metastasis system stages, smoking status, and age. Positive correlation was observed between nuclear RelA and cytoplasmic pIkappaB-alpha. Both nuclear RelA and cytoplasmic pIkappaB-alpha were associated with poor prognosis by univariate and multivariate analyses. CONCLUSIONS: Nuclear RelA and cytoplasmic pIkappaB-alpha expression are associated with a poorer prognosis in NSCLC patients. In particular, composite application of these two biomarkers might be of greater value than application of a single marker to identify patients at high risk, even at an early clinical stage.

[DNA binding activity of nuclear factor-kappa B in human astrocytoma].

BACKGROUND & OBJECTIVE: Transcription factors of human cancer cells can regulate the expression of many malignancy-related gene products,relate to poor differentiation,and high metastasis of cancer cells,and also inhibit apoptosis of cancer cells. This study was designed to investigate the nuclear factor-kappa B (NF-kappaB)DNA binding activity in human astrocytoma tissue,and its significance with human astrocytoma development. METHODS: The NF-kappaB DNA binding activities of 12 cases of normal brain tissue, and 37 cases of human astrocytoma tissue were detected by electrophoretic mobility shift assay (EMSA), and photo densitometry. RESULTS: The absorbency of NF-kappaB DNA binding activity in human astrocytoma tissue was 134.2+/-24.1, higher than that in normal brain tissue (97.5+/-1.9)(P< 0.05). The NF-kappaB DNA binding activity in multiform glioblastoma tissue was highest (106.8+/-7.4), that in anaplasia Astrocytoma was 123.2+/-10.1, in astroblastoma was 139.3+/-16.8,and in astrocytoma was 160.2+/-18.6 (P< 0.05). CONCLUSION: The NF-kappaB DNA binding activity correlates with malignancy degree of human astrocytoma.