skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Amplification and rearrangement of the Kirsten ras oncogene in virus-transformed BALB/c 3T3 cells during malignant tumor progression

Journal Article · · Proc. Natl. Acad. Sci. U.S.A.; (United States)

Analyses of the cellular and viral Kirsten ras genes (c-Ki-ras and v-Ki-ras, respectively) during malignant tumor progression were performed by using Kirsten murine sarcoma virus-transformed BALB/c 3T3 cells that harbor a replication-defective provirus. After injection into athymic nude mice by four different routes, primary tumors and secondary lung metastases were isolated, adapted to in vitro growth, and analyzed for DNA levels and mRNA expression of both genes for comparison with the originally injected transformed cells and untransformed 3T3 cells. For all tumors (primary or secondary), the v-Ki-ras gene was amplified and v-Ki-ras mRNA expression was highly elevated above that observed in the original transformed cell population. In two of five lung metastases from the i.v. and footpad injection routes, rearranged Ki-ras DNA sequences were observed. Micrometastases from the s.c. route of injection did not display these alterations. Injection of footpad lung tumor cells with rearrangements into a second group of animals led to multiple lung metastases with even further rearrangements correlating with more effective lung colonization/growth ability. However, reinjection of an i.v. lung tumor with rearranged Ki-ras led to no further rearrangements in the lung microfoci tumors isolated > 40 days after injection. These data suggest (i) the significance of amplification and elevated expression of v-Ki-ras in tumor formation, (ii) correlation of this amplification with more effective tumor progression, and (iii) the selective advantage that cells with Ki-ras DNA sequence additions have in the formation of overt lung tumors.

Research Organization:
Case Western Reserve Univ., Cleveland, OH (United States)
OSTI ID:
5172528
Journal Information:
Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 84:15
Country of Publication:
United States
Language:
English