Objective To establish a mouse model of prostate cancer expressing human PSCA for the development of new anti-tumor drugs or vaccines. Methods The total RNA of DU145 cells,a human prostate cancer cell line,was isolated by using TRIzol reagent according to the (RT-PCR),the first-strand cDNA was synthesized using the SuperScript First-Strand synthesis system. The human PSCA gene was amplified with the primers and cloned into the plasmid pcDNA3.1 to generate pcDNA-PSCA. DNA sequencing was used to confirm the constructs. The mouse prostate tumor cell line RM-1 cells,syngeneic to C57BL/6,were transfected with pcDNA-PSCA plasmids followed by selection using G418. RT-PCR analysis was performed to examine the validity of the constructs. Expression of PSCA on the cell surface was determined by staining with anti-PSCA antibody,and the anti-PSCA antibody was detected using an FITC-conjugated goat anti-rabbit IgG antibody,and analyzed by flow cytometry. 4-6-week-old male C57BL/6 mice purchased from the Laboratory Animals Center were inoculated with different amounts of RM-PSCA cells to search for suitable cell population which can form tumor in mouse,and the mice were monitored twice a week. The growth and the survival time of mice were measured,respectively. The tumor volume was measured by vernier caliper according to the formula:V=0.5a×b~2,where a and b are the long and short diameters of the tumor,respectively. Results The plasmid pcDNA-PSCA was successfully constructed and the PSCA was successfully expressed in RM-PSCA 7~# and RM-PSCA 28~# cells by RT-PCR and confirmed by flow cytometry. 1×10~5 RM-PSCA cells were sufficient to get tumor growth in 100% of inoculated mice. The tumor grew quickly and the volume of the tumor reached 12000 mm~3 within 34 days. All the mice died within 40 days and their mean survival time was 37 days. Conclusion A PSCA-expressing tumor model in mice has been successfully established. It can be used to evaluate the activities of drugs or vaccines.

Objective To study the role of protective antigen(PA)and N-terminal segment of lethal factor (LFn)in the entrance of EGFP(enhanced green fluorescent protein)into HeLa cells. Methods The DNA fragments encoding LFn and EGFP were amplified,respectively,and cloned into the plasmid pET-21 a(+)one after another to construct a recombinant plasmid pET-LFn-EGFP. The plasmid was txansformed into BL21 cells to express LFn-EGFP protein under the induction of IPTG. The protein was purified by Ni chelating chromatography. After incubation with LFn-EGFP in the presence of PA or not, the HeLa cells were analyzed by flow cytometry or laser confocal microscopy. Results The fusion protein LFn-EGFP was purified by over 90% homogeneity and retained the ability of LF to bind with PA when incubated with J774A.1 macrophage cells,and could get into HeLa cells. Conclusion The LFn-EGFP could enter the HeLa cells in a PA independent pathway. But PA could help more LFn-EGFP molecules enter into HeLa cells.