Functional screening for miRNAs targeting Smad4 identified miR-199a as a negative regulator of TGF-ß signalling pathway.

The transforming growth factor-ß (TGF-ß) signalling pathway participates in various biological processes. Dysregulation of Smad4, a central cellular transducer of TGF-ß signalling, is implicated in a wide range of human diseases and developmental disorders. However, the mechanisms underlying Smad4 dysregulation are not fully understood. Using a functional screening approach based on luciferase reporter assays, we identified 39 microRNAs (miRNAs) as potential regulators of Smad4 from an expression library of 388 human miRNAs. The screening was supported by bioinformatic analysis, as 24 of 39 identified miRNAs were also predicted to target Smad4. MiR-199a, one of the identified miRNAs, was inversely correlated with Smad4 expression in various human cancer cell lines and gastric cancer tissues, and repressed Smad4 expression and blocked canonical TGF-ß transcriptional responses in cell lines. These effects were dependent on the presence of a conserved, but not perfect seed paired, miR-199a-binding site in the Smad4 3'-untranslated region (UTR). Overexpression of miR-199a significantly inhibited the ability of TGF-ß to induce gastric cancer cell growth arrest and apoptosis in vitro, and promoted anchorage-independent growth in soft agar, suggesting that miR-199a plays an oncogenic role in human gastric tumourigenesis. In conclusion, our functional screening uncovers multiple miRNAs that regulate the cellular responsiveness to TGF-ß signalling and reveals important roles of miR-199a in gastric cancer by directly targeting Smad4.

Novel sinomenine derivative 1032 improves immune suppression in experimental autoimmune encephalomyelitis.

Sinomenine (SIN) is an alkaloid isolated from the Chinese medicinal plant Sinomenium acutum. It is widely used as an immunosuppressive drug for treating autoimmune diseases. Due to its poor efficiency, the large-dose treatment presents some side effects and limits its further applications. In this study, we used chemical modification to improve the therapeutic effect of SIN in vitro and in vivo. A new derivative of sinomenine, named 1032, demonstrates significantly improved immunosuppressive activity over that of its parent natural compound (SIN). In an experimental autoimmune encephalomyelitis (EAE) model, 1032 significantly reduced encephalitogenic T cell responses and induced amelioration of EAE, which outcome was related to its selective inhibitory effect on the production of IL-17. By contrast, SIN treatment only led to a moderate alleviation of EAE severity and the expression level of IL-17 was not significantly reduced. Furthermore, 1032 exhibited suppression of Th17, but not Treg, cell differentiation, a result probably related to its inhibitory effect on IkappaB-alpha degradation as well as on IL-6 and TNF-alpha secretion in BMDCs. We speculate that 1032 as a novel anti-inflammatory agent may target DC to block IL-6 production, which in turn would terminate Th17 cell development. Thus, SIN derivative 1032 presents considerable potential in new drug development for treating autoimmune and inflammatory disease.

[The relationship between the parotid glands function and the dose-volume effect in nasopharyngeal carcinoma patients with intensity-modulated radiation therapy].

OBJECTIVE: To study the preservation of parotid glands function and relationship between parotid glands function and dose-volume histogram (DVH) in nasopharyngeal carcinoma (NPC) patients treated by intensity modulated radiation therapy (IMRT). METHODS: From August 2002 to December 2004, the excretion index (EI) and uptake index (UI) of parotids in 48 NPC patients underwent radical IMRT was examined by ECT at the beginning, the end of and the 3 months after radiotherapy. The relationship between parotid function (EI and UI) and DVH were analyzed. RESULTS: The mean doses to the contralateral parotid and ipsilateral parotid were 22.8 +/- 4.5 Gy and 31.9 +/- 4.1 Gy, respectively. The symptom of xerostomia was mild at the end of radiotherapy. ECT showed EI of contralateral parotid were 0.35 +/- 0.25, 0.31 +/- 0.24 and 0.33 +/- 0.22 at the beginning, the end of and 3 months after radiotherapy (RT), respectively. UI were 7.12 +/- 3.56, 5.81 +/- 2.25 and 5.72 +/- 2.81 at the same intervals. This shows no statistical difference. The EI and UI of ipsilateral parotid at the completion of radiotherapy declined significantly (0.21 +/- 0.16 and 4.87 +/- 2.45, respectively) compared with those of pre-treatment (0.36 +/- 0.27 and 8.02 +/- 3.89, respectively) (P < 0.05). DVH showed: at the end of RT, the EI was significant difference between mean dose < 26 Gy and > or = 26 Gy group (P = 0.009) and decreased significantly in the group of V25 (the percentages of parotid volume irradiated with < 25 Gy) > or = 50% compared with the group of V25 < 50% (P < 0.01). The UIs were no significant difference in two groups (P > 0.05). CONCLUSION: 26 Gy is a threshold dose for the preservation of parotid glands function. There is also a threshold volume irradiated for the preservation of the parotid glands function. Based on the precondition of assuring significant dose to the target volume (PTV), we should reduce the irradiated volume and dose to parotid glands as possible as we can so as to preserve its function.

[Investigation of emission characteristics for light duty vehicles with a portable emission measurement system].

Emission from 7 typical light-duty vehicles under actual driving conditions was monitored using a portable emission measurement system to gather data for characterization of the real world vehicle emission in Shenzhen, including the effects of driving modes on vehicle emission, comparison of fuel consumption based emission factors (g x L(-1) with mileage based emission factors (g x km(-1)), and the average emission factors of the monitored vehicles. The acceleration and deceleration modes accounted for 66.7% of total travel time, 80.3% of traveling distance and 74.6%-79.2% of vehicle emission; the acceleration mode contributed more than other driving modes. The fuel based emission factors were less dependent on the driving speed; they may be utilized in building macro-scale vehicle emission inventory with smaller sensitivity to the vehicle driving conditions. The effect of vehicle technology on vehicle emission was significant; the emission factors of CO, HC and NO(x) of carbureted vehicles were 19.9-20.5, 5.6-26.1 and 1.8-2.0 times the more advanced vehicles of Euro II, respectively. Using the ECE + EUDC driving cycle would not produce the desired real-world emission rates of light duty vehicles in a typical Chinese city.