[ ABSTRACT] AIM:To investigate the effect of microRNA-375 ( miR-375) on the viability, cell cycle and apop-tosis of HCT116 cells.METHODS: The expression of miR-375 in different colorectal cancer cell lines was detected by real-time PCR.The miR-375 mimics was transfected into HCT116 cells by LipofectamineTM 2000.The mRNA expression of miR-375 and AEG-1 was detected by real-time PCR.The HCT116 cell viability was detected by MTT assay.The changes of apoptosis and cell cycle distribution were analyzed by flow cytometry.RESULTS:Real-time PCR showed that miR-375 expression was the lowest in HCT116 among 4 colorectal cancer cell lines.The expression level of miR-375 significantly in-creased in miR-375 mimics group compared with that in the negative control group.The high expression level of miR-375 significantly inhibited the mRNA expression of AEG-1.After transfection with miR-375 mimics, the cell viability was in-hibited, the apoptotic rate was increased, the proportion of G1-stage cells was increased, and the proportion of S-stage cells was decreased.CONCLUSION:miR-375 inhibits the viability, mediates the cell cycle arrest and promotes the apoptosis of colon cancer HCT116 cells.miR-375 may act as a tumor suppressor in colorectal cancer by inhibiting AEG-1.

BACKGROUND: Human keratinocyte growth factor-2 (hKGF-2) has extensive physiological functions, which plays an important role in embryonic development, tissue-repairing, nervous regeneration, vascularization and development of tumor.OBJECTIVE: To clone hKGF-2 gene, obtain the expression of hKGF-2 in Escherichia coli(E.coli) and determine its bioactivity, so as to provide experimental basis for further investigation.DESIGN: Open experiment.SETTING: Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention.MATERIALS: The experiment was conducted in State Key Laboratory of Viral Genetic Engineering, Institute for Viral Disease Control and Prevention of Chinese Center for Disease Control and Prevention. The temperature control expression vector pBV220 was constructed by State Key Laboratory of Viral Genetic Engineering; EcoR Ⅰ , BamH Ⅰ , T4 DNA ligase (Promega Co., Ltd.); The specific polymerase chain reaction (PCR) of hKGF-2 (Manufactured by Shanghai Boya Biotechnology Co., Ltd.); Heparin-Sepharose CL-6B (Pharmacia Company); PCR rapid purification kit,Trizol kits for total RNA extract, Kits for RT-PCR (GIBCO Co., Ltd.); Kits for rapid extraction of plasmid DNA (Boda Company); BL-21-codon plus compent cells (Stratagene Co., Ltd.).METHODS: High-expression strain BL-21 codon plus competent cells was used to express and purify initially recombinant hKGF-2 protein, and its activity was detected. RT-PCR was adopted to obtain hKGF-2 cDNA from lung tissues of naturally aborted fetus and clone it into pBV220 carri er plasmid. The hKGF-2 protein expressed in BL-21 codon plus competent cells of E.coli. Affinity chromatography and ion exchange chromatography were applied in isolation and purification, and the bioactivity of expression protein was determined in cell proliferation test.MAIN OUTCOME MEASURES: The length and sequence of cDNA segment in hKGF-2, the expression of hKGF-2 gene inE.coli and the purification of hKGF-2 activity.RESULTS: The segment of hKGF-2 cNDA was about 500 bp, and hKGF-2 protein highly expressed in BL-21, which had soluble expression in the supernatant. SDS-PAGE showed that the relative molecular mass was about 20000, and hKGF-2 protein could significantly promote the mitotic activity of NIH3T3 cells. The A value (490 nm) of hKGF-2 in the 1 μg/L, 5 μg/L and 10 μg/L groupswere higher than that in the blank control group, and the differences were significant (which were 0.174±0.022,0.220±0.029,0.306±0.050,0.066±0.004 respectively,P ＜ 0.001).CONCLUSION: hKGF-2 gene is successfully cloned, which highly expresses in BL-21 of the E.coli. Purified hKGF-2 protein can stimulate the proliferation of NIH3T3 cells and significantly promote its mitotic activity.

Objective To establisha multiplex STR genotyping m ethod for autosom al STR and Y-STR loci in forensic biological practice. Methods W idely used autosom al STR loci and Y-STR loci w ere se-lected. A set of PC R prim ers w as designed, and a 5-dye fluorescent labeled STR multiplex PC R reagent kit w as developed. Results A kit w as developed w hich can sim ultaneously detect 15 autosom al STR loci, 10 Y-STR loci, and an Amelogenin. Conclusion The 15 autosom al STR plus 10 Y-STR kit in com bination w ith capillary electrophoresis m ethod w as used to STR genotyping w ith accurate and reli-able results. The new one-step testing kit can potentially be w idely used in forensic cases and D N A databank in the future.