Effect of metformin on apoptosis of renal cell carcinoma cells in vitro and its mechanisms / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of metformin on the apoptosis of renal cell carcinoma (RCC) cells in vitro and its mechanisms.</p><p><b>METHODS</b>Fluorescent microscopy and flow cytometry were used to examine the changes in the apoptosis of 786-O cells after metformin treatment. The possible signaling molecules involved in this process were analyzed by immunoblot analysis of AMP-activated protein kinase (AMPK) signaling and caspase 9.</p><p><b>RESULTS</b>Metformin induced apoptosis and caspase 9 activation in 786-O cells in low-serum medium but not in normal-serum medium. Metformin also induced AMPK activation in 786-O cells, but this activation was not associated with the cell proliferation inhibition or apoptosis-inducing effect of metformin.</p><p><b>CONCLUSION</b>Metformin can induce apoptosis of RCC cells in vitro, suggesting its potential as a therapeutic agent for RCC.</p>

Protein kinase D3 is involved in negative regulation of MMP-7 in prostate cancer cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the role of protein kinase D3 (PKD3) in the regulation of matrix metalloproteinases 7 (MMP-7) expression in prostate cancer cells.</p><p><b>METHODS</b>PC-3 cells were either stimulated with 100 nmol/L PMA to activate PKD3 kinase activity, or transiently transfected with PKD3 siRNA, and the relative expression level of MMP-7 mRNA were analyzed by real-time PCR using 2(-delta delta Ct) method. MMP-7 mRNA levels were also analyzed and quantified in HEK293 cells with over-expression of wild-type PKD3, PKD3 knockdown (using PKD3 siRNA), or over-expression of wild-type PKD3 followed by PKD3 knockdown.</p><p><b>RESULTS</b>MMP-7 mRNA expression in PC3 cells was significantly decreased after PMA-induced PKD3 kinase activation. In contrast, PKD3 knockdown by siRNA transfection markedly increased MMP-7 mRNA level (P<0.01). MMP-7 mRNA level in HEK293 cells was significantly decreased by PKD3 over-expression, whereas obviously increased by PKD3 knockdown. Down-regulation of MMP-7 mRNA level in HEK293 induced by PKD3 over-expression was rescued by PKD3 knockdown.</p><p><b>CONCLUSION</b>PKD3 may contribute to the malignant progression of prostate cancer cells through negative regulation of MMP-7 expression.</p>

PKD3 contributes to up-regulation of prostate-specific antigen in prostate cancer cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of PKD3 in prostate-specific antigen (PSA) expression regulation in androgen-dependent prostate cancer cells and explore the mechanism.</p><p><b>METHODS</b>LNCaP cells containing low level of PKD3 were transfected with pEGFP-C2 or pEGFP-PKD3 plasmid followed by dihydrotestosterone (DHT) treatment, and PSA mRNA level was analyzed by RT-QPCR using 2(-delta delta Ct) method. Wild-type or kinase-dead PKD3 plasmids, human androgen receptor plasmid pSVAR0, pMMTV-luc of AR luciferase reporter and renilla luciferase reporter pRL-SV40 were cotransfected into HEK293 cells, and after treatment with DHT for 24 h, the cells were harvested and AR transcriptional activity were determined by dual-luciferase reporter assay. The subcellular localization of endogenous PKD3 and AR and their colocalization induced by DHT were observed by confocal microscopy.</p><p><b>RESULTS</b>PSA mRNA level triggered by DHT was significantly increased by overexpression of pEGFP-PKD3 in LNCaP cells compared with that in pEGFP-C2 control cells (P<0.001). AR transcription in response to DHT treatment was also significantly up-regulated by wild type PKD3 expression (P<0.001), but partially down-regulated by kinase-dead PKD3 mutant (P<0.01). Endogenous PKD3 and AR in LNCaP cells not only translocated from the cytoplasm to the nucleus, but also colocalized with each other after DHT stimulation.</p><p><b>CONCLUSION</b>Elevated AR transcriptional activity and enhanced expression of PSA induced by PKD3 in response to DHT treatment suggest that PKD3 contributes to the proliferation and malignant growth of androgen-dependent prostate cancer cells.</p>

Antitumour effects on human colorectal carcinomas cells by stable silencing of phospholipase C-gamma 1 with lentivirus-delivered siRNA / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>In most colorectal carcinomas, the level of phospholipase C (PLC)-gamma 1 expression is greatly elevated. Increased expression of PLC-gamma 1 may play an important role in colon carcinogenesis, but the mechanism is not well known. The aim of this study was to evaluate the role of PLC-gamma 1 in colon carcinogenesis by using recombinant lentivirus that stably suppressed the PLC-gamma 1 expression in human colorectal carcinoma LoVo cells.</p><p><b>METHODS</b>Recombinant lentivirus producing PLC-gamma 1 siRNA were prepared. After LoVo cells were transduced by each lentivirus, stably transduced cells were selected by Blasticidin. The protein and mRNA expression of PLC-gamma 1 were examined by Western-blot and reverse transcription-polymerase chain reaction (RT-PCR) analysis, and the effects of the lentivirus on the cell adhesion, migration and apoptosis were analyzed.</p><p><b>RESULTS</b>Stable LoVo cell line deficient in PLC-gamma 1, was established. Notably, PLC-gamma 1 was silenced without affecting the levels of other subtypes of PLC so that the role of PLC-gamma 1 in colon carcinogenesis could be examined. Silencing of endogenous PLC-gamma 1 resulted in efficient inhibition of the adhesion and migration of LoVo cells in vitro and a great increase of 5-fluorouracil induced apoptosis (30%-40%) of LoVo cells.</p><p><b>CONCLUSIONS</b>PLC-gamma 1 may play an important role in metastasis and anti-apoptosis in human colorectal carcinomas.</p>

Phosphoprotein affinity profiling--a novel method for screening regulators of lipopolysaccharide signaling pathway / 南方医科大学学报

<p><b>OBJECTIVE</b>To To establish a method of phosphoprotein affinity profiling for identifying phosphoproteomic differences between Thp-1 cells with or without lipopolysaccharide (LPS) stimulation, aiming to screen potential regulators involved in LPS pathway.</p><p><b>METHODS</b>Thp-1 cells were stimulated with 100 ng/ml PMA for 48 h to induce differentiation into mature macrophages, which, after culture for another 48 h in the absence of PMA, were either treated with 100 ng/ml LPS for 30 min or left untreated. After desalting procedure with ultrafiltration, the phosphoproteins enriched by phosphoprotein metal affinity column (PMAC) of both groups were run on 2-D electrophoresis to find the spots with different phosphorylation status. Finally, some of these spots were identified by mass spectrometry (MS) and subsequent bioinformatic analysis.</p><p><b>RESULTS</b>Compared to untreated Thp-1 cells, LPS stimulated Thp-1 cells showed 29 spots with reproducible alterations on the 2-D map, including 8 representing up-regulated spots, 7 new spots, 10 down-regulated spots, and 4 absent spots. The newly emerged and absent protein spots were subjected to MS analysis, and 4 of them were identified to be involved in various cellular processes such as proteolysis, signal transduction and protein folding. Among these, phosphorylation of proteasome C2 subunit was dramatically up-regulated in LPS-stimulated cells, as was consistent with previous reports; the phosphorylation of Z-DNA-binding protein 1 has not been reported so far and needs further confirmation.</p><p><b>CONCLUSION</b>Phosphoprotein affinity profiling is an attractive method for screening novel regulators involved in LPS signaling pathways and can be widely used in systemic study of signal transduction.</p>

Effects of pentobarbital sodium on rhythmical respiration of neonatal rat medullary preparations / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the effects of pentobarbital sodium in generation and modulation of rhythmical respiration in neonatal rats.</p><p><b>METHODS</b>The effects of pentobarbital sodium were examined on hypoglossal nerve (XII) rootlets and inspiratory neurons in the medullary preparations including the medial region of the nucleus retrofacialis, pre-Bötzinger complex and the dorsal respiratory group of neonatal rats aged 0-3 days. The electrical activity of XII nerve rootlets and inspiratory neurons were recorded. Different doses of pentobarbital sodium (20, 40, 60, 80 micromol/L) were added into modified Krebs solution to observe changes in the discharge activity of XII nerve and inspiratory neurons. Bicuculline was used to further investigate the mechanisms that pentobarbital sodium suppresses respiration.</p><p><b>RESULTS</b>The discharge activity inhibition of XII nerve was increased as pentobarbital sodium doses increased from 20 to 60 micromol/L, but no significant difference was observed between the doses of 60 and 80 micromol/L. Bicuculline can partly restore the rhythmical respiration discharge activity.</p><p><b>CONCLUSION</b>Pentobarbital sodium can suppress respiration partly via GABAA receptors.</p>

Changes of the proportion and mortality of pulmonary thromboembolism in hospitalized patients from 1974 to 2005 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pulmonary thromboembolism (PTE) has become a common disease that severely endangers people's health. This study analysed the changes in proportion and mortality of PTE in hospitalized patients to provide data for prevention and management of the disease.</p><p><b>METHODS</b>The data of 763 hospitalized patients with PTE from 1974 to 2005 in Fuwai Hospital were analysed.</p><p><b>RESULTS</b>During the 1970s, 0.27% of patients in a cardiovascular hospital had PTE (< 5 cases per year); while so far this century the proportion is 0.94% (48 to 113 per year). The mortality of hospitalized PTE patients fell from 20.00% in the 1970s to 4.10% this century. Prior to 1990, the mortality of hospitalized PTE patients was 12.50%, and in the years after 1990 only 3.40%. The difference was statistically significant (P < 0.005). People with this disease were mostly between the ages of 30 and 69 years. Men were most susceptible between the ages of 30 and 69 years, while women between the ages of 40 and 69 years. Men contracted PTE 10 years earlier than women. The mortality of male PTE patients was 4.70%, not significantly different from female patients, 5.06% (0.50 < P < 0.75). There were not any significant differences between the mortality of patients in the different age groups overall (< or = 39, 40 - 49, 50 - 59, and > or = 60 years, P > 0.1). More people contracted the disease in winter than in other seasons (P < 0.05). There was no obvious difference between the mortality in different seasons overall (0.75 < P < 0.90).</p><p><b>CONCLUSION</b>PTE is an increasingly significant disease and deserves adequate attention.</p>