OBJECTIVESTo investigate whether hepatitis B virus X gene alone is sufficient to transform the non-transformed immortalized human liver cell line QSG7701 and induce hepatocellular carcinoma in vivo.

METHODSpCMVX/QSG7701 cells were transplanted into subcutaneous tissue of nude mice. pRcCMV2/QSG7701 and QSG7701 cells were used as control. Tumor formation was checked within 5 weeks after transplantation. The activity and food intake of the nude mice were recorded. The texture, volume and metastasis of transplantation tumor were observed grossly, and the HE stained transplantation tumor tissues were observed under optical microscope.

RESULTSThe transplantation tumor occurred in all of the six nude mice inoculated with pCMVX/QSG7701 cells at the second week after inoculation. No metastatic tumor was found in other organs. Transplant tumor was not formed in all of the negative control groups. The activity, eating and drinking of the nude mice transplanted with pCMVX/QSG7701 cells were normal, while their weights were increased gradually in the first 3 weeks. Since the 4th week after transplantation with pCMVX/QSG7701 cells, the activity of the mice was decreased and their body weight was no longer increased. It is interesting that the mental state and eating of those nude mice inoculated with pRcCMV2/QSG7701and QSG7701 cells were normal, and the weight was increasing all the time after inoculation. HE staining analysis confirmed that the transplanted tumor was hepatocellular carcinoma.

CONCLUSIONHBx alone is sufficient to transform the non-transformed immortalized human liver cell line QSG7701 and induce hepatocellular carcinoma in vivo.