H-ras expression, genetic instability, and acquisition of metastatic ability by rat prostatic cancer cells following v-H-ras oncogene transfection.
To study the relationship between metastatic ability, mutated H-ras expression, and genetic instability, a cloned, nonmetastatic rat prostatic cancer cell line (AT2.1) was transfected with the v-H-ras oncogene. The parental AT2.1 clone, 4 control transfectants (Neo/Only), and 9 v-H-ras transfectants (Neo/Ras) were characterized with regard to their H-ras content by using Southern, Northern, and Western blot analysis and their biological behavior in vivo. Following s.c. inoculation in syngeneic rats, all transfectants produced tumors. All 4 (Neo/Only) transfectants like the parental untransfected cell were non-metastatic. Six of 9 Neo/Ras transfectants were metastatic to the lungs and lymph nodes, while the other 3 Neo/Ras transfectants were not metastatic. There was no simple dose-response relationship between the level of v-H-ras integration, mRNA or p21 protein expression, and the development of metastatic ability by the Neo/Ras transfectants. Cytogenetic analysis demonstrated that the frequency of additional structural and/or additional numerical chromosomal changes among the Neo/Ras transfectants was significantly higher than that in the Neo/Only transfectants (P less than 0.05). Loss of chromosome 10 was observed in all of the Neo/Ras transfectants, whereas that was observed in only one of the 4 Neo/Only transfectants (P less than 0.05). There were no specific chromosomal changes, however, which were statistically correlated with the development of metastases in the Neo/Ras transfectants. These results demonstrate that development of the metastatic ability in AT2.1 cells is not a single-step reaction regulated by the level of H-ras expression alone, but rather a complex process requiring additional events. One of the additional events appears to be an increase in genetic instability and cytogenetic changes following v-H-ras transfection.
Ichikawa
T
T
Department of Urology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Schalken
J A
JA
Ichikawa
Y
Y
Steinberg
G D
GD
Isaacs
J T
JT
D000818:Animals; D002460:Cell Line; D015321:Gene Rearrangement; D011905:Genes, ras; D007621:Karyotyping; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D009362:Neoplasm Metastasis / Q000235:genetics*; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology; D051381:Rats; D011919:Rats, Inbred Strains; D014162:Transfection