Enhanced chemosensitivity of drug-resistant osteosarcoma cells by lentivirus-mediated Bcl-2 silencing.

The Bcl-2 gene is frequently overexpressed in malignancy and is responsible for the resistance induced by chemotherapeutic drugs. The aim of this study was to investigate whether the inhibition of Bcl-2 by lentivirus-mediated RNA interference would enhance doxorubicin cytotoxicity in the drug-resistant human osteosarcoma MG63 cells. Downregulation of Bcl-2 was confirmed by quantitative reverse transcription PCR and Western blotting. Moreover, the ratio of Bcl-2/Bax decreased due to the downregulation of Bcl-2 expression and the upregulation of Bax expression. Decreased cyclin D1 expression was also detected. Flow cytometry and MTT assays revealed that Bcl-2 knock-down increased cellular apoptosis and the MG63 cells became sensitive to doxorubicin. However, no detectable alterations in MDR1 or Bcl-xl expression were observed. Therefore, lentivirus-mediated Bcl-2 knock-down may sensitize these human osteosarcoma cells to doxorubicin and provide a potential therapeutic strategy for osteosarcoma.

[Memory monitoring in mild cognitive impairment].

OBJECTIVE: To explore the profile of changes of memory monitoring in patients with mild cognitive impairment (MCI). METHODS: Rey- auditory verbal learning test (AVLT) and feeling-of-knowing (FOK) test in episodic memory (EM) and semantic memory (SM) were conducted on 30 MCI patients, 17 males and 13 females, aged (66 +/- 9), and 30 age, education level, word fluency test, and digit span-matched healthy persons as healthy control (HC) group. RESULTS: The EM impairment of the MCI group was (13.7 +/- 2.8), significantly higher than that of the HC group [(8.1 +/- 2.0), P < 0.01], but the SM impairment of the MCI group was (5.4 +/- 1.4), not significantly different from that of the HC group [(5.0 +/- 1.4), P > 0.05]. The EM-FOK of the MCI patients with correct judgment and false recognition was (41.8 +/- 13.2)%, significantly higher than that of the HC group [(28.1 +/- 11.6)%, P < 0.01], however, the SM-FOK levels of the MCI patients with different judgment and recognition were all not significantly different from those of the HC group (all P > 0.05). CONCLUSION: The MCI patients overestimate their memory performance on episodic FOK, but their SM monitoring is not impaired. The deficit of memory monitoring in MCI may be the foundation of subjective memory complaints and is useful for diagnosis of MCI. EM and SM monitoring may depend on different neural mechanisms.

Effects of monocyte-endothelium interactions on the expression of type IV collagenases in monocytes.

The adhesion of monocytes to endothelial cells is one of the early stages in the development of atherosclerosis. The expression of type IV collagenases, which include matrix metalloproteinase (MMP)-2 and MMP-9, in monocytes is hypothesized to play an important role in monocyte infiltration and transformation into foam cells. The aim of the present study was to examine the effects of monocyte-endothelium interactions on the expression levels of type IV collagenases and their specific inhibitors in monocytes, and to investigate the roles of tumor necrosis factor (TNF)-α and interleukin (IL)-1ß in this process. Monocytes were single-cultured or co-cultured with endothelial cells. The expression of the type IV collagenases, MMP-2 and MMP-9, and their specific inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2, in monocytes was determined by immunohistochemistry followed by image analysis. The expression levels of MMP-2 and MMP-9 were found to be low in the single-culture monocytes, but increased significantly when the monocytes and endothelial cells were co-cultured. However, treatment with monoclonal TNF-α or IL-1ß antibodies partially inhibited the upregulated expression of MMP-2 and MMP-9 in the co-cultured monocytes. Expression of TIMP-1 and TIMP-2 was observed in the single monocyte culture, and a small increase in the expression levels was observed when the monocytes were co-cultured with endothelial cells. Therefore, monocyte-endothlium interactions were shown to increase the expression of type IV collagenases in monocytes, resulting in the loss of balance between MMP-2 and -9 with TIMP-1 and -2. In addition, TNF-α and IL-1ß were demonstrated to play important roles in this process.

PI3K/AKT signaling pathway plays a role in enhancement of eNOS activity by recombinant human angiotensin converting enzyme 2 in human umbilical vein endothelial cells.

The aim of this study was to investigate the effect of PI3K/AKT signaling pathway in the activity of recombinant human angiotensin converting enzyme 2 (rhACE2) promoted the activity of endothelial nitric oxide synthase (eNOS). The human umbilical vein endothelial cells (HUVEC) were cultured in vitro. Then treated with Ang II (1×10(-6) mol/L) for 24 h. The rhACE2 (100 µmol/L) was added and incubated for 5, 10, 15, 30, 60 min respectively which was based on Ang II intervention. The effect of rhACE2 on phosphorylation eNOS level was also observed in the presence of LY294002 (10 µmol/L) (PI3K/AKT inhibitors). Griess reagent method was applied to measure NO contents in cell culture supernatant, RT-PCR to detect the expression of eNOSmRNA in HUVEC, and Western blot to detect the expression of eNOS and phosphorylated eNOS. In Ang II intervention group, NO contents were significantly lower than control group (P < 0.05). Through rhACE2 treatment, the NO contents in cell culture medium and the expression level of phosphorylated eNOS were significantly higher than in Ang II intervention group (P < 0.05), but eNOSmRNA and non-phosphorylated eNOS protein expression level showed no significant difference (P > 0.05). After HUVEC was intervened by PI3K/AKT pathway inhibitor LY294002, the expression level of phosphorylated eNOS was significantly lower than that in the rhACE2 30 min treatment group (P < 0.05). rhACE2 may reduce the activity of Ang II inhibited endothelial cell eNOS, which can be blocked by PI3K/AKT pathway inhibitor LY294002, suggesting PI3K/AKT signaling pathway plays an important role in rhACE2's promotion of the activity of endothelial cell eNOS.