Proporties of SV4O-transformed Human Cells

SV40 바이러스로 형질전환된 사람종양세포의 특성

A few SV4O-transformed human cells such as SV8O are potentially tumorigenic but rejected by athymic hosts. However, one cell line in this group (W118IVA-2) is known to be fully tumorigenic. Two clones were obtained after the injection of W118IVA-2, of which NW1SC1-1 was tumorigenic but NW18C1-2 was not in nude mice. As examined by Southern blot analysis, NW18C1-1 appears to contain more copy number of SV40 sequences than NW18C1-2 does. However, it was unable to demonstrate that this difference elicits the tumorigenicity in NW18C1-1 but not in NW18C1-2. Therefore, the latter clone was tested if it expresses SV40 early genes to produce large T as well as small t antigens using indirect immunofluorescent assay and immunoprecipitation. In addition, mouse NIH3T3 cells were transfected with the cellular DNA of NW1SC1-2 as well as that of NW18C1-1 to examine if the viral genomes in the clones can make the nontransformed cells to acquire malignant growth potential in vivo. The transformed cells expressed large T antigen and became tumorigenic. Thus, the transforming functions of NW1SC1-2 cell appers to be intact. These results clearly suggest that the inability of NW18C1-2 cell to form tumor in nude mice is not because they are inherently nontumorigenic. However, the possibility that the interaction of SV40 with its host differs in these clones can not he ruled out.

SV80와 같은 SV40로 형질전환된 사람세포는 종양을 일으킬 수 있는 능력을 가지고 있으나 면역기구인 흉선이 없는 누드마우스에서는 거부반응을 일으켜 종양을 일으키지 않는다. 그러나, 예외적으로 WI18/VA-2세포는 누드마우스에서 종양을 일으키며 이에서 얻는 두클론중 NW18C11은 종양을 일으키나 NW18C12는 종양을 일으키지 않는다. 본 실험에서는 이들 두 클론의 차이점들을 조사하였다. 실험결과, NW18C11은 NW18C12보다 더 많은수의 SV40 sequence를 포함하고 있음을 southern blot방법을 통해 확인하였으며 또한 immunofluoresce와 immunoprecipitation방법을 사용하여 두 클론 모두 정상크기의 SV40유전자산물인 large T와 small t 단백질을 생성함을 확인하였다. 한편 두 클론내에 포함되어 있는 바이러스유전자가 비형질전환새포로 하여금 생체내에서 악성종양 형성능력을 획득하도록 형질전환시킬수 있는지 확인하기 위해 두 클론의 DNA를 추출하여 마우스 NIH3T3세포에 주입시켜 형질전환된 세포를 선별하였다. 이 세포들은 모두 large T단백질을 생성하였으며 누드마우스에서 종양을 일으켰다. 이들 결과로써 NW18C12세포의 형질전환능은 완전하며, 이 세포가 누드마우스에서 거부반응에 기인하는 것으로 생각된다.