Objective To assess the genetic stability of doxorubicin resistant sarcoma 180 cell line(S 180R) after in
vivo passages. Methods Flow cytometry, Southern blot, Northern blot and RT PCR were used to examine genes and molecules related to drug
resistance. Results The drug efflux of S 180R was nearly 100 fold as high as that of the parental cells. The ratio of half peak width to peak height was 0.23 as compared to 0.56 measured two
years before when the S 180R cell line was
initially established. The mdr 1 gene was significantly amplified and transcribed while the transcription of topoisomerase Ⅱ α gene was
decreased. However there was no increase in mRNA
expression of the multidrug resistance associated protein(MRP). Conclusion Compared with the initially established S 180R, its resistance to doxorubicin is not only maintained but in fact has been increased since in vivo passage for 2 years. The major mechanism is amplification and over expression of mdr 1 gene, but decreased topoisomerase Ⅱ α also contributes. S 180R is an ideal experimental model for the study of doxorubicin resistance and its reversion.
More abstracts about the Molecular biological evidence for the genetic stability of in vivo passaged doxorubicin resistant ce