ABSTRACT
BRAF is one of the most important pro-oncogenes, which is mutated in approximately 8% of human tumors. The most common BRAF mutation is a valine-to-glutamate transition (V600E) that is expressed primarily in melanoma, colorectal cancer and thyroid carcinoma. MEK/ERK is constitutively activated in the cells expressing BRAFV600E, leading to tumor development, invasion, and metastasis. Therefore, BRAFV600E is a therapeutic target for melanoma and some other BRAFV600E tumors. Vemurafenib, a BRAFV600E inhibitor, which was approved by FDA for the treatment of late-stage melanoma in 2011, produces improved rates of overall and progression-free survival in patients with the BRAFV600E mutation, making a dramatic breakthrough in melanoma treatment. Vemurafenib is also an individual target drug based on genetic diagnosis. However, its therapeutic success is limited by the emergence of drug resistance. Therefore, it is important to explore the mechanisms underlying the resistance for developing new inhibitor drugs and for preventing or delaying the resistance evolution to BRAF inhibitor drugs. In this review, we described the role of BRAFV600E as an anti-tumor drug target and the development of BRAF inhibitors. We also discussed the mechanisms leading to resistance of BRAFV600E inhibitors. Furthermore, therapeutic strategies that might be employed to overcome acquired resistance were proposed.
ABSTRACT
Objective: To observe the effects of Tangnaikang (TNK), a compound traditional Chinese herbal medicine, on glucose metabolism and insulin resistance in obese Zucker rats. Methods: Twelve male obese Zucker rats, 6 weeks old, were randomly divided into control group and TNK group (3.24 g/kg) after being fed for 2 weeks. All rats received high-fat diet and 4-week treatment. Body weight and blood glucose were tested every week. Oral glucose tolerance test (OGTT) was performed and fasting insulin level was tested on days 0, 14 and 28. Triglyceride, cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and free fatty acids (FFA) were tested on day 28. Glucose infusion rate (GIR) was tested by hyperinsulinemic-euglycemic clamp from day 29. The protein expressions of protein kinase B (Akt), phospho-Akt (p-Akt) (Thr308) and glucose transporter protein 4 (GLUT4) in skeletal muscle and GLUT4 in adipose tissue were measured after hyperinsulinemic-euglycemic clamp test. Results: Compared with the control group, the fed blood glucose level and glucose level of OGTT at 120 min had a significant decline in TNK group on day 28, and TNK caused no alteration of the fasting serum insulin, and the GIR increased significantly in hyperinsulinemic-euglycemic clamp study. Furthermore, TNK increased Akt and p-Akt (Thr308) protein expressions in skeletal muscle and decreased the protein expression of GLUT4 in white adipose tissue. Body weight, and triglyceride, cholesterol, LDL-C and FFA contents were slightly decreased in the TNK group, but there were no statistically significant effects. Conclusion: TNK increases the protein expressions of Akt and p-Akt (Thr308) of the signal transduction pathway to influence the translocation of GLUT4 in skeletal muscle and improves glucose metabolism by reducing insulin resistance.
ABSTRACT
Objective To determine the content of cholesterol in Gekko Gecko.Methods High performance liquid chromatography was performed on Hypersil ODS2 (4.6 mm?150 mm,5 ?m).The chromatorgraphic conditions were as follows:methanol as mobile phase,flow rate being 1.0 mL/min and detecting wavelength at 208 nm.The column temperature was 40 ℃.Results A good linearity of cholesterol was shown in range of 0.885～14.000 ?g (r=0.999 5),the average recovery was 99.65%,RSD=3.45% (n=6).Conclusions This method is simple,rapid and accurate,and may provide a reliable way for the quantification of cholesterol in Gekko Gecko.