Identification of differentially expressed genes involved in multidrug resistance in K562/A02 by cDNA microarray / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the molecular mechanism underlying multidrug resistance (MDR) and identify unknown genes that might be involved in drug resistance development in K562/A02 cells.</p><p><b>METHODS</b>K562/A02 was induced by gradually increasing the ADM concentration in culture medium of K562 cells, the differential expression of associated genes between K562 and K562/A02 was determined with cDNA microarray. Overexpression of neurofilament protein NF-H gene in K562/A02 cells was confirmed with RT-PCR and immunocytochemistry. Anti-sense oligodeoxynucleotides were transfected into K562/A02 cells by lipofectamine in order to further analyze the role of NF-H in drug resistance.</p><p><b>RESULTS</b>Comparing with the expression profiles, we found upregulation of 5 transcripts and downregulation of 7 transcripts in response to MDR of K562/A02 cells. The overexpression of NF-H, one of the 5 upregulated genes, was confirmed. After being treated with antisense oligodeoxynucleotides of NF-H and mdr1, the cellular adriamycin concentration increased significantly, but antisense NF-H alone did not have significant effect on drug resistance phenotype.</p><p><b>CONCLUSION</b>The development of MDR in K562/A02 cells is multifactorial. NF-H may be involved in the drug resistance of K562/A02, which may provide a new marker of diagnosis and a new target of therapy.</p>

Effects of 3-substituted aryl oxindole(PH II-7) on cell cycle of tumor cells / 药学学报

<p><b>AIM</b>To study the antitumor mechanism of 3-substituted aryl oxindole (PH II-7) and determine its effects on cell cycle distribution of tumor cells.</p><p><b>METHODS</b>The cell cycle distributions were determined with FACS. The cell cycle regulation-related proteins of K562 lysates were analyzed with Western Blot. The inhibition of PH II-7 on DNA synthesis of tumor cells were estimated though 3H-thymidine incorporation and the tyrosine kinase activity of EGFR of A431 lysates was measured with ELISA.</p><p><b>RESULTS</b>PH II-7 effected cell cycle distribution of several tumor cells, including multidrug resistant tumor cell lines, and accumulation of cells in the G0-G1 stages was observed. The cell cycle regulation-related proteins CDK2, Rb and c-myc were inhibited by PH II-7 in a dose dependent manner, whereas the expression of CyclinE was increased after exposure to PH II-7. Furthermore, PH II-7 2.0 mg.L-1 was shown to inhibit the incorporation of 3H-thymidine into DNA, and 21.89%-41.29% of the PTK activity of EGFR in A431 lysates was inhibited by PH II-7 2-8 mg.L-1 in a dose-dependant manner.</p><p><b>CONCLUSION</b>PH II-7, a new anti-tumor agent, blocks the transition of cell cycle of tumor cells from G1 to S phase by inhibition CDK2.</p>

Preliminary studies on the mechanisms of a new anti-tumor agent PH II-7 with special preference to multidrug resistant tumor cells / 中国医学科学院学报

<p><b>OBJECTIVE</b>To determine the anti-tumor activity of PH II-7 in vitro and explore preliminarily its mechanisms.</p><p><b>METHODS</b>The anti-tumor activity was measured using colorimetric MTT assay. Apoptosis was determined with fluorescence-activated cell sorter (FACS), electron microscopy and agarose gel electrophoresis. The expressions of mdr1 and sorcin genes were determined by Northern blot assay.</p><p><b>RESULTS</b>PH II-7 inhibited the proliferation of various human tumor cells derived from different tumor cell lines. The IC50 values varied from 0.34-18.61 mumol/L. Especially, PH II-7 had strong inhibitory effect on multidrug resistant tumor cells, whereas adriamycin (ADR) was resistant. Apoptosis was induced in HL60 and HL60/ADR cells treated with 1 microgram/ml PH II-7, while PH II-7 inhibited the expressions of mdr1 and sorcin genes.</p><p><b>CONCLUSIONS</b>PH II-7 is a new potential agent which has strong inhibitory effect on both multidrug resistant cells and their parental cells. PH II-7 may increase the intracellular drug concentration in MDR cells by inhibiting the expressions of the MDR-related genes mdr1 and sorcin and induce the apoptosis of MDR cells and their parental tumor cells.</p>