[Expression and significance of c-fos in resistant cell line TU177/VCR of larynx squamous cell carcinoma]

Objective: To explore the effect of c-fos on multidrug resistance of laryngeal cancer TU177 cells. Method: Increasing drug concentration gradient is adopted to establish the stability of the laryngeal cancer drug resistance in cell line; RT-PCR and Western blot were used to detect difference of the c-fos between TU177 and TU177/VCR cells; plasmids with human c-fos knockdown or over expression were transfected into TU177/VCR and TU177 cells respectively, and the effects of different treatment on cell proliferation were investigated with MTT. Results: The drug resistance of TU177/VCR cells was 26.25-fold in vincristine (VCR), 7.33-fold in Paclitaxel (TAX), 2.41 in cisplatin (DDP), and 5.50 in 5-fluorouracil (5-FU), comparing with TU177( P<0.05). The TU177/VCR cells had significantly higher c-fos expression compared to TU177 cells( P<0.05). The results showed that the IC(50) values of 5-FU for the NC group and c-fos shRNA group were (306.2±6.3)μmol/L and (81.3±3.9)μmol/L, respectively, which was decreased by 73% in the c-fos shRNA group compared to that in the NC group (P<0.05). Similarly, the results showed that the IC(50) values for 5-FU were (55.3±9.4) μmol/L in NC group and (288.1±7.3)μmol/L in c-fos WT group, which was increased 5.21-fold in c-fos WT cells. Conclusion: C-fos plays important role in multidrug resistance of larynx cancer cell TU177/VCR, and might become a new molecular target for laryngeal cancer treatment.

[FAT1 inhibits cell proliferation of esophageal squamous cell carcinoma through regulating the expression of CDK4/CDK6/CCND1 complex]

Objective: To explore the expression of FAT1 in esophageal squamous cell carcinoma (ESCC) tissues, and its effect on cell proliferation. Methods: The expression levels of FAT1 protein in human ESCC tissues and matched adjacent normal tissues were determined by immunohistochemistry (IHC). Lentivirus based knockdown of FAT1 was carried out in YSE2 and Colo680N cell lines and 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H tetrazolium bromide (MTT) assays was performed to examine the effect of FAT1 on the proliferation of these ESCC cells. Colony formation assay was used to detect the colony formation ability. Flow cytometry was performed to analyze the cell cycle and apoptosis. The expression levels of cell cycle markers in FAT1 knock out ESCC cell lines were detected by real-time quantitative reverse transcription polymerase chain reaction(qRT-PCR) and Western blot. Results: The relative expression of FAT1 in ESCC tissues was 66.97±21.53, significantly lower than 78.13±16.76 of adjacent normal tissues(P<0.05). Knockdown of FAT1 promoted cell proliferation and colony formation. In YSE2 cell, the division time in negative control (NC) group was (1 570±51) min, significantly longer than (1 356±31) min in shFAT1 group. In Colo680N cell, division time in NC group was (1 532±53) min, significantly longer than (1 290±30) min in shFAT1 group (P<0.05). Knockdown of FAT1 promoted G1-to S-phase transition and resulted in the upregulation of CDK4/CDK6/CCND1. Conclusion: FAT1 inhibits the proliferation and G1-to S-phase transition of ESCC cells through regulating the protein expression of CDK4/CDK6/CCND1 complex.

[Photodegradation assay method of nifedipine and its application to studies on percutaneous absorption]

A new method of analysis for low concentrations nifedipine was developed according to the principle of a photodegradation analytical method that has been reported by the authors previously, and was used to study percutaneous absorption. The absorbance of sample solution was measured before and after light irradiation at 237 nm for 2 h. In this method, calibration graph was linear in the range of 1-20 micrograms/ml for delta A237. The average recovery for nifedipine was 98.80%. No interference from propylene glycol, azone, m-nifedipine, nitrendipine, verapamil and propranolol was observed. It is shown that azone can promote markedly percutaneous absorption of nifedipine.

[Determination of m-nifedipine and its pharmacokinetic study in rabbits by high-pressure liquid chromatography]

A high-pressure liquid chromatographic method was developed for determination of m-nifedipine in plasma using a chemical bonded C-18 phase column (YWG-C18 10 microns, made in China) with nitrendipine as internal standard. To increase life of the YWG-C18 column a mixture of methanol and 5 mmol.L-1 phosphate buffer (70:30 vol/vol) was selected as mobile phase with a flow rate of 0.8 ml.min-1. The method was sensitive to m-nifedipine 3 ng.ml-1 plasma and the standard curve was linear from 10 to 1000 ng.ml-1 with correlation coefficient of 0.99. The within-day and day-to-day precisions (CV) of this method were 4.5% and 7.0%, respectively, with recoveries of 95-102% (10-1000 ng.ml-1). There was no interference with nifedipine, amiodarone, propranol, and verapamil. A pharmacokinetic study on m-nifedipine was carried out in 8 rabbits. A better computer fitted to a two-compartment model was observed using 3P87 program. The parameters obtained were as follow: Vc 6.3 L.kg-1, Cl 0.021 L.kg-1.min-1, T1/2 alpha 30 min, T1/2 beta 230 min, AUC 102 micrograms.min.ml-1.