关键词: 耐药性, 不稳定遗传, 可逆突变, 雷帕霉素

Abstract:

Reversible alterations at DNA sequence or epigenetic levels can result in phenotypes that are unstably inherited. The reversibility of these inheritable changes might be uniquely beneficial for adaption to possible fluctuations in environment. However, in traditional studies, especially in the cause of drug resistance, unstable changes are always ignored for the genetic instability. In this study, we conduct a specific genetic screen in fission yeast using rapamycin (+caffeine) and obtain 173 resistant isolates. In contrast to the common strategy of isolating stable genetic mutants, we passage the cell culture with rapamycin resistance on drug free condition and test the resistance of offspring every five days, and obtained 14 strains that exhibit unstable resistance to rapamycin (the drug resistance is lost randomly among the cell progenies without drug selection pressure). Further studies show that the unstable genetic resistance of some strains is regulated by reversible DNA sequence alterationat the ssp1 gene locus. This study provide new insights and relevant scientific basis for the regulatory mechanism of unstable drug resistance in the process of rapamycin as a clinical anti-tumor drug, and a new possible target for solving the problem of drug resistance.