The Utility Of β-hCG Expressing SiHa Cervical Cell Line On Quantifying Tumor Mass In Living Animal

[Background]: Animal model is an essential tool for cervical cancer research, esp in cancer therapic research. However, there are little convenient methods to quantifying tumor mass in living animal. Current method is introducing tumor cells subcutaneously. While this method works well for visually evaluating tumor growth in animals over time, it is not efficient for internally determining tumor growth, metastasis, or treatment effects at various time points.[Objectives]: This study was designed to transfect pCIneo-β hCG vectors into SiHa cells in order to establish a β-hCG expressing SiHa cell line for monitoring tumor mass in vivo by determination of urinary β hCG[Methods]: The constructed pCIneo-β hCG were amplified in DH5 α (E.coli) and extracted in alkaline lysis way. A mixture of 0.8 μg pCIneo-β hCG DNA and 2 μl of lipofectamine2000 was prepared for transfection of SiHa cells in 24-cell culture plate. After transfection, the cells were incubated at 37°C for 48 hours. Cells were then transfered into selection medium which contained 750μg/ml G418. Cells cultured continually for 7 days, and single-cell colonies were picked up and cultured in selection medium containing 200 μg/ml G418 for 20days, The stable transfected cell line was named SiHa-hCG.β hCG in culture medium was detected by Electrochemi-luminescence immunoassay method. MTT growth curve was observed and invasion ability was tested by animal experiment.We injected SiHa-hCG cells into 15 femal BALB/c mice through subcutaneously, 5×10⁶ cells each mouse. Urine were collected every other day. β hCG were measured and creatinine was also assayed for reference. Urinary βhCG/ creatinine was used to monitor tumor growth. On the 9^th,11^th,13^thand 15^th day,3 mice were killed each time and tumor weights were measured and correlated with Urinary βhCG/ creatinine of the right day. The last 3 mice were chemotherapied by cisplatin. 10mg/Kg each time on the 15th day and 18th day. Urinary β hCG/ creatinine were also determined every other day.We also injected SiHa cells into 3 mice, and collected Urine every other day and measured βhCG/ creatinine for comparison.[Result]: The concentration of β hCG of SiHa-hCG cell culture medium was much higher than that of SiHa cell. Growth curve test and invasion test both showed negative difference between SiHa-hCG cell and SiHa cell. After injection of βhCG expressing SiHa cells, the value of urinary β-hCG/creatinine was increased when there is no visual detection of tumor, urinary β-hCG/creatinine was increased continually while the comparative group which was inject with SiHa cells showed no increase . urinary β-hCG/creatinine in SiHa-hCG cell tumor mice had a positive linear correlation to tumor weight in (r=0.9829). After therapy by cisplatin, the value of urinary β-hCG/creatinine declined rapidly.[Conclusion]: We set up a new β-hCG expressing siha cervical cancer cell line for quantifying tumor mass in living animal. Urinary β-hCG/creatinine closely correlated with the tumor mass in vivo and can monitor tumor growth sensitively, conveniently and continously. This study provides a new cervical cancer model which can monitor tumor growth at " real time" and offers a new tool for cervical cancer research.