OBJECTIVETo investigate the effects of arsenic trioxide (As(2)O(3)) on the apoptosis and P-glyco-protein (P-gp) expression of multidrug-resistant human leukemia K562/ADM cells, and the combined effects of As(2)O(3) with conventional chemotherapeutic agents.

METHODSMultidrug-resistant human leukemia cell line K562/ADM that overexpresses mdr-1 gene was used as the target cells. The cell proliferating activity was assessed with a MTT assay. Cell morphology was examined by light microscopy, confocal microscopy and electron-microscopy. P-gp expression, cell-cycle status were determined by flow cytometry.

RESULTSK562/ADM cells were highly resistant to adriamycin, and cross-resistant to daunorubicin and etoposide. As(2)O(3) at concentrations of 0.5 to 20 micromol/L inhibited the proliferation of K562/ADM cells, and K562/ADM cells were more sensitive to As(2)O(3) than their parent K562 cells did. As(2)O(3) induced marked apoptosis of K562/ADM cells showed by typical apoptotic morphological changes and the appearance of high sub-G(1) cell population. As(2)O(3) significantly inhibited the P-gp expression in K562/ADM cells, and exerted a synergistic effect on the enhancement of the cell sensitivity to adriamycin, daunorubicin and etoposide.

CONCLUSIONAs(2)O(3) induces growth-inhibition and apoptosis of multidrug-resistant K562/ADM cells, and augments synergistically the sensitivity of the cells to conventional chemotherapeutic agents via down-regulation of P-gp expression.

ATP-Binding Cassette, Sub-Family B, Member 1 ; biosynthesis ; drug effects ; Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Arsenicals ; pharmacology ; Daunorubicin ; pharmacology ; Doxorubicin ; pharmacology ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Drug Synergism ; Etoposide ; pharmacology ; Humans ; K562 Cells ; Oxides ; pharmacology

BACKGROUNDTo confirm if Puumala like viruses exist in China.

METHODSRNA was extracted from lungs of bank voles captured in the Northeast China, partial S segments genome of Puumala viruses were amplified and sequenced.

RESULTS926 bp cDNA of S segments of Puumala like virus was amplified and sequenced. The phylogenetic analysis revealed that the Puumala like viruses found in China were most close to that found in Far East region of Russia.

CONCLUSIONSPuumala like virus does exist in Northeast China, and the nucleotides sequence of the viruses have high homolog to Puumala viruses found in Russia.

Animals ; China ; DNA, Viral ; analysis ; Hemorrhagic Fever with Renal Syndrome ; virology ; Lung ; virology ; Mice ; Phylogeny ; Puumala virus ; isolation & purification ; Sequence Analysis, DNA ; Sequence Homology, Nucleic Acid