Indirect correlation between gene dosage and increased mRNA level in multidrugresistance cancer cells

ABSTRACT

The human lymphoblasts CCRF-CEM cells selected in Vinblastine, Actinomycin-D, Adriamycin and Vincristine is associated with amplification of mdrl gene. This amplification is accompanied by increase levels of mdrl mRNA and gene dosage. The level of mdrl mRNA appears to correlate proportionally with the levels of drug resistance. No each observation was found with regard to the genomic DNA. It seems that once gene amplification occures in a given drug Concentration, it remains at the same level of amplification even higher concentration despite of the parallel correlation between the drug concentration and the level of mdrl mRNA