Objective To explore the role of chromokinesin KIF4A in gastric cancer cell invasion using gastric cancer cells SGC-7901 and chromokinesin KIF4A deficient gastric cancer cells (SGC-shKIF4A).Methods Expression levels of KIF4A in controlling gastric cancer cells (SGC-shNC) and SGC-shKIF4A cells were determined by Western Blot.Invasion of gastric cancer cells were assessed using Transwell invasion assay and the number of cells passing through the matrigel was counted.Changing numbers of cortactin in SGC-7901,SGC-shNC,and SGC-shKIF4A cells were analyzed by immunofluorescence staining.Results Compared to the SGC-shNC cells,invasion ability of SGC-shKIF4A cells was increased.Compared to other cells,the numbers of cortactin in SGC-shKlF4A cells was also increased suggesting invadopodia in these cells was increased(P＜0.01).Conclusions Chromokinesin KIF4A acts as a tumor suppressor by inhibiting gastric cancer cells invasion and the results provides strong evidences for KIF4A serving as one of potent targets for gastric cancer prognostics and treatment in clinic.

Objective To purify pre-ribosome and ribosome of mammalian ceils using continuous sucrose density gradient ultracentrifugation.Methods Continuous sucrose density gradient was established by ultracentrifugation,and the continuous sucrose density gradient of 10％-30％ and 10％-45％ were used to extract the pre-ribosome and ribosome in mammalian cells,respectively.The mammalian cell lysis buffer was added to the established continuous sucrose density gradient.Pre-ribosome and ribosome with different sedimentation coefficients were collected and the A260 absorbance of each sample was measured.Proteins of each sample were extracted to detect the large subunit protein,RPL15 by Western Blot.Results Large subunit ribosomal protein RPL15 exists on 60S of the pre-ribosome,and also on 60S,80S and polyribosome of mature ribosome.Conclusions The continuous sucrose density gradient,which is established by the swing-out rotor,can be used to isolate the pre-ribosome and ribosome of mammalian cells rapidly.This method has the advantages of good separation effect and simple operation,which provides a good method for rapid and large amount preparation and separation of various kinds of ribosomes.

Objective To investigate the process that chromosome kinesin KIF4A promote cisplatin resistance in lung cancer cells.Methods Reverse transcription PCR (RT-PCR) and Western Blot experiments were performed to analyze the expression of KIF4A in lung cancer cells A549 and cisplatin (DDP) resistant cells A549/ DDP.Cell transfection, RNA interference (RNAi) experiments and thiazolyl blue tetrazolium bromide (MTT) assays were carried out to examine cell proliferation of A549 cells with overexpression of exogenous KIF4A and A549/DDP cells with depletion of endogenous KIF4A after cisplatin treatment.Results Expression of KIF4A in A549/DDP cells was higher than that in A549 cells.With overexpression of exogenous KIF4A, A549 cells displayed drug resistance to cisplatin.On the contrary, depletion of endogenous KIF4A in A549/DDP cells resulted in cisplatin sensitivity.Conclusions Chromosome kinesin KIF4A involves in the regulation of cisplatin resistance in lung cancer cells and KIF4A may be a potential and effective new biological target for treatment of lung cancer cisplatin resistance.