  As a cheap and safe antimalarial agent, chloroquine (CQ) has been used in the
battle against malaria for more than half century. However, the mechanism of CQ
action and resistance in Plasmodium falciparum remains elusive. Based on
further analysis of our published experimental results, we propose that the
mechanism of CQ action and resistance might be closely linked with
cell-cycle-associated amplified genomic-DNA fragments (CAGFs, singular form =
CAGF) as CQ induces CAGF production in P. falciparum, which could affect
multiple biological processes of the parasite, and thus might contribute to
parasite death and CQ resistance. Recently, we found that CQ induced one of
CAGFs, UB1- CAGF, might downregulate a probable P. falciparum cystine
transporter (Pfct) gene expression, which could be used to understand the
mechanism of CQ action and resistance in P. falciparum.
