The Fas-mediated apoptotic pathway in cardiac myxoma

Cell differentiation in cardiac myxomas: confocal microscopy and gene expression analysis after laser capture microdissection

Cardiac myxomas are rare tumors with a heterogeneous cell population including properly neoplastic (lepidic), endothelial and smooth muscle cells. The assessment of neoplastic (lepidic) cell differentiation pattern is rather difficult using conventional light microscopy immunohistochemistry and/or whole tissue extracts for mRNA analyses. In a preliminary study, we investigated 20 formalin-fixed and paraffin-embedded cardiac myxomas by means of conventional immunohistochemistry; in 10/20 cases, cell differentiation was also analyzed by real-time RT-PCR after laser capture microdissection of the neoplastic cells, whereas calretinin and endothelial antigen CD31 immunoreactivity was localized in 4/10 cases by double immunofluorescence confocal microscopy. Gene expression analyses of α-smooth muscle actin, endothelial CD31 antigen, alpha-cardiac actin, matrix metalloprotease-2 (MMP2) and tissue inhibitor of matrix metalloprotease-1 (TIMP1) was performed on cDNA obtained from either microdissected neoplastic cells or whole tumor sections. We found very little or absent CD31 and α-Smooth Muscle Actin expression in the microdissected cells as compared to the whole tumors, whereas TIMP1 and MMP2 genes were highly expressed in both ones, greater levels being found in patients with embolic phenomena. α-Cardiac Actin was not detected. Confocal microscopy disclosed two different signals corresponding to calretinin-positive myxoma cells and to endothelial CD31-positive cells, respectively. In conclusion, the neoplastic (lepidic) cells showed a distinct gene expression pattern and no consistent overlapping with endothelial and smooth muscle cells or cardiac myocytes; the expression of TIMP1 and MMP2 might be related to clinical presentation; larger series studies using also systematic transcriptome analysis might be useful to confirm the present results.

Cytotoxicity induced by nanobacteria and nanohydroxyapatites in human choriocarcinoma cells

We explored the cytotoxic effects of nanobacteria (NB) and nanohydroxyapatites (nHAPs) against human choriocarcinoma cells (JAR) and the mechanisms of action underlying their cytotoxicity. JAR cells were co-cultured with NB and nHAPs for 48 h, and ultrastructural changes were more readily induced by NB than nHAPs. Autophagy in the plasma of JAR cells were observed in the NB group. The rate of apoptosis induced by NB was higher than that for nHAPs. The expression of Bax and FasR proteins in the NB group was stronger than that for the nHAP group. NB probably resulted in autophagic formation. Apoptosis was possibly activated via FasL binding to the FasR signaling pathway.

Mipu1 protects H9c2 myogenic cells from hydrogen peroxide-induced apoptosis through inhibition of the expression of the death receptor Fas

Mipu1 (myocardial ischemic preconditioning upregulated protein 1), a novel rat gene recently identified in our lab, was expressed abundantly and predominantly in the brain and heart and upregulated in myocardium during myocardial ischemia/reperfusion in rats. In our previous study we found that Mipu1 was an evolutionarily conserved zinc finger-containing transcription factor. However, whether Mipu1 confers myocardial protection remains unknown. In this study, H9c2 myogenic cells were treated with hydrogen peroxide (H₂O₂) to simulate oxidative stress during myocardial ischemia-reperfusion injury. The expression of Mipu1 at mRNA and protein levels was detected by RT-PCR and Western blotting analysis. To study the effect of Mipu1 on apoptosis and expression of Fas induced by H₂O₂, full-length Mipu1 cDNA and Mipu1-RNAi plasmids were transiently transfected into H9c2 myogenic cells, and flow cytometry was used to quantitate the percentage of apoptotic cells. The expression of Fas was analyzed by Western blotting assay. The DNA binding and transcription activities of Mipu1 to the Fas promoter were detected by chromatin immunoprecipitation and luciferase reporter assays. The results showed that exposure of H9c2 myogenic cells to H₂O₂ resulted in a dose- and time-dependent increase in Mipu1 mRNA and protein levels; Mipu1 over-expression inhibited H₂O₂-induced apoptosis and upregulation of Fas induced by H₂O₂ in H9c2 myogenic cells; and knockdown of Mipu1 by RNAi promoted apoptosis and upregulation of Fas induced by H₂O₂. The chromatin immunoprecipition and reporter assays showed the DNA binding and transcription suppressor activities of Mipu1 to Fas promoter region. These results indicate that Mipu1 protected H9c2 myogenic cells from H₂O₂-induced apoptosis through inhibiting the expression of Fas.

[Effects of magnetic fluid hyperthermia induced by an alternative magnetic field on human carcinoma A549 cell in vitro]

背景与目的

磁流体热疗是将纳米技术和热疗相结合的一种新兴热疗方法，具有高度的靶向性和特异性，已成为目前研究的热点。本研究旨在探讨Fe₃O₄纳米磁流体热疗在体外对人肺癌A549细胞的影响。

方法

在体外将不同浓度的Fe₃O₄纳米磁流体和人肺癌A549细胞共培养，在交变磁场中作用30 min，采用MTT法细胞计数、流式细胞术、倒置显微镜、透射电镜等方法观察磁流体热疗对人肺癌A549细胞活细胞数的光密度值、杀伤率、细胞形态、细胞周期及凋亡情况的影响。

结果

磁流体热疗后人肺癌A549细胞增殖受到明显抑制，活细胞数的光密度值下降；杀伤率（cytotoxity index, CI）增加；细胞凋亡率逐渐增强；细胞周期停滞于S期，S期细胞和G₂期增加，与磁流体浓度呈明显依赖关系。电镜观察磁流体热疗后的肺癌细胞呈凋亡样改变，高温时呈坏死样改变。

结论

磁流体热疗能明显抑制人肺癌A549细胞的增殖，诱导凋亡，阻滞细胞于S期。