The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ + sulphadoxine (S) + pyrimethamine (P), MQ alone and MQ + ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of [3H] hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the IC50 values of CQ and QN, as well as between the IC50 values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.
Animals ; Antimalarials/*pharmacology/therapeutic use ; Artemisinins/pharmacology/therapeutic use ; Chloroquine/pharmacology/therapeutic use ; *Drug Resistance ; Humans ; Malaria/drug therapy/*parasitology ; Mefloquine/pharmacology/therapeutic use ; Parasitic Sensitivity Tests/methods ; Plasmodium falciparum/*drug effects/isolation & purification ; Quinine/pharmacology/therapeutic use ; Thailand

OBJECTIVE: To explore the combined pro-apoptosis effect of HSP90 inhibitor BIIB021 and chloroquine (CQ) in chronic myeloid leukemia (CML) cells bearing T315I mutation and its mechanism. METHODS: The p210-T315I cells were divided into 4 groups by different treatment: control, BIIB021, CQ, and BIIB021 + CQ. After treated with BIIB021 or/and CQ for 24 hours, Annexin V/PI binding assay was used to detect apoptosis rates of CML cells. DAPI staining was used to observe nuclear fragmentation, and Western blot was used to detect the expression of caspase 3, PARP (apoptosis related proteins) and p62, LC3-I/II (autophagy related proteins). P210-T315I cells were inoculated subcutaneously into mice and CML mouse models were established. The mice in treatment groups were injected with BIIB021 and/or CQ while mice in control group were treated with PBS and normal saline. The tumor volume of mice was measured every 4 days, and protein level of cleaved-caspase 3 and LC3-II in tumor tissue were detected by immunohistochemistry. RESULTS: The results showed that BIIB021 induced apoptosis of CML cells in a dose-dependent manner ( r=0.91). CQ could enhance the apoptosis-inducing effect of BIIB021. Flow cytometry analysis results showed that the apoptosis rate of p210-T315I cells in combination group was higher than that in BIIB021 or CQ only group (P<0.05). DAPI staining showed nuclear fragmentation in combination group could be observed more obviously. Western blot analysis showed that BIIB021 could induce LC3-I to convert to LC3-II and decrease p62 protein levels (P<0.05). Moreover, the combination group had higher expression of LC3-II, p62 (P<0.05), activated PARP and activated caspase 3 than BIIB021 only group (P<0.05). Besides, experiment in vivo showed the mean tumor volume in co-treatment group was lower than that in single drug group (P<0.01). Immunohistochemistry of tumor tissue also showed the protein level of cleaved-caspase 3 and LC3-II in combined group was higher than that in BIIB021 only group. CONCLUSION HSP90 inhibitor BIIB021 induced significant apoptosis of CML cells bearing T315I both in vivo and in vitro. CQ can enhance this effect probably by autophagy inhibition.
Adenine/analogs & derivatives* ; Animals ; Apoptosis ; Autophagy ; Caspase 3/metabolism* ; Cell Line, Tumor ; Chloroquine/therapeutic use* ; Fusion Proteins, bcr-abl/pharmacology* ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy* ; Mice ; Mutation ; Poly(ADP-ribose) Polymerase Inhibitors/therapeutic use* ; Pyridines