In order to study the enhancement of immune functions and autologous tumor-killing (ATX) activity by kappa-selenocarrageenan (KSC) in mice bearing sarcoma 180, the effects of KSC and/or Cyclophosphamide (Cy) on natural killer(NK) activity, lymphokine activated killer(LAK) activity, the production of interleukin-2 (IL-2), ATK activity and the growth of sarcoma 180 (S180) were observed. The results showed that KSC promoted NK activity, LAK activity and ATK activity in vivo, increased IL-2 production at 40mg/kg ?d x 9d. It also enhanced the antitumor action of Cy (20mg/kg?d x 9d) and offsetted the inhibition of Cy on immunocompetent cells. The ATK activity in splenocytes of SI80-bearing mice could be induced and augmented by recombinant interleukin-2 (rIL-2) in vitro. In conclution, KSC had a up-regulating effect on immune functions and ATK activity in tumor-bearing mice, therefore, can be used as a biological response modifier (BRM) in cancer biotherapy.

Object To study the augmentation of the T activated killer (T AK) cell proliferating and tumor killing activities of the polysaccharide fraction from Rhodiola kirilowii (Regel) Regel, Lycium barbarum L., Hedysarum polybotrys Hand. Mazz., Glehnia littoralis F. Schmidt ex Miq., Rehmannia glutinosa (Gaert.) Libosch. ex Fisch. et Mey. and Aloe barbadensis Mill. in vitro. Methods The T AK cells were induced by anti CD 3 antibody (CD 3McAb) and rIL 2 from human peripheral blood mononuclear cells (PBMC). The effects of the above six plant polysaccharides (1～100 ?g/mL) on the proliferation of T AK cell, the cytotoxicity to Raji cells and L 1210 cells, and the IL 2 receptor (IL 2R) expression in T AK cells were determined. Results The six polysaccharides alone had no obvious effect on the proliferation of T AK cells. In the presence of rIL 2 and CD 3McAb, they could reinforce the proliferation of T AK cells and its tumor killing activities against Raji cells and L 1210 cells at a different extent, and a 21%～68% increase of IL 2R expression in T AK cells was observed. Conclusion The plant polysaccharides significantly enhance the proliferation and the tumoricidal activities of T AK cells and the enhancing actions related to the increase of IL 2R expression.

Background and purpose:Drug-resistance is the main obstacle in terms of efficacy of chemotherapy for leukemia, RNA interference(RNAi) strategy possesses the characteristics of specilization, high-efficiency and low-toxicity, and can effectively and specifically inhibit the overexpression of given gene. This study was designed to investigate the effect of small interfering RNA (siRNA) on expression of mdr1 gene and drug-resistance in multidrug-resistant human leukemia K562/ADM cell.Methods:Human multidrug-resistant leukemia cell line K562/ADM over-expressing mdr1 gene was used as the target cells, Two siRNAs (si-mdr1-1 and si-mdr1-2) targeted mdr1 gene were chemically synthesized and transfected into K562/ADM cells. Expression of mdr1 mRNA was determined by RT-PCR, P-glycoprotein (P-gp) expression was measured using flow cytometry (FCM), and the sensitivity of K562/ADM cells to adriamycin was assessed with a MTT colorimetric assay.Results:Two siRNAs (si-mdr1-1 and si-mdr1-2) specially designed in this study could markedly down-regulate the expression of mdr1 mRNA and its product P-gp in K562/ADM cells. After cells transfected with si-mdr1-1 or si-mdr1-2 for 24h and 48h, the inhibition of mdr1 mRNA expression in the cells for si-mdr1-1 was 55.5% and 22.5%; and for si-mdr1-2, 16.0% and 57.6%, respectively. Treated with siRNA for 72h, the expression intensity of P-gp in the two transfected cell lines decreased 74% and 85%, respectively. Both si-mdr1-1 and si-mdr1-2 significantly enhanced the sensitivity of K562/ADM cells to adriamycin and reversed their drug-resistance, the reversal efficiency was 2.52-folds and 1.96-folds, respectively.Conclusions:The siRNA could effectively and specifically silence the expression of mdr1 gene and overcome the drug-resistance mediated by P-gp in K562/ADM cells.

Aim To investigate the effect of 2-deoxy-D-glucose(2-DG)on the sensitivity of leukemia multi-drug resistant K562/ADMcells to adriamycin by inhib-iting glycolytic pathway as well as its molecular mecha-nisms.Methods The leukemia drug-resistant K562/ADM cells and parental K562 cells were used as the target cell models.The cell proliferating activity was assessed with an MTT colorimetric assay,and the gly-colysis including glucose consumption,lactate export, and hexokinase activity was determined by glucose, lactic acid and hexokinase (HK)testing kits.The ex-pression and phosphorylation of mammalian target of rapamycin(mTOR)and glucose transporter-4 (GLUT-4)expression were analyzed by western blot.Results K562/ADM drug-resistant cells possessed higher HK activity,GLUT-4 expression level and aerobic glycolic ability than K562 sensitive cells. 2-DG treatment markedly inhibited HK activity,glucose consumption, and lactate export both in K562 cells and K562/ADM cells,and suppressed the proliferation of the two cells in a time-and concentration-dependent manner.Low concentration of 2-DG or adriamycin could increase the expression and phosphorylation of mTOR.However, the co-administration of 2-DG and adriamycin markedly counteracted adriamycin-mediated enhancement of mTOR expression and phosphorylation and down-regu-lated GLUT-4 expression in K562/ADM cells,and 2-DG dramatically improved the sensitivity of K562/ADM cells to cytotoxicity.Conclusion 2-DG inhibits the proliferation of drug-resistant K562/ADM cells and en-hances the sensitivity to adriamycin by blocking aerobic glycolysis pathway through inhibiting hexokinase activi-ty,counteracting adriamycin-stimulated increased ex-pression and phosphorylation of mTOR and downregu-lating GLUT-4 expression.

OBJECTIVETo investigate the effects of arsenic trioxide (As(2)O(3)) on the apoptosis and p-glycoprotein (P-gp) expression of multidrug-resistant human leukemia cells.

METHODSHuman multidrug-resistant leukemia cell line K562/ADM overexpressing the MDR1 gene, was used as the target cells. The cell proliferating activity was assessed using the MTT colorimetric assay. Cytomorphology was investigated under light, confocal and electron microscopes. DNA fragmentation was examined using agarose gel electrophoresis, while p-gp expression, cell cycle status and sub-G1 cells were determined using flow cytometry.

RESULTSZero point five to 20 micromol/L As(2)O(3) inhibited the proliferation of K562/ADM cells, and K562/ADM cells were more sensitive to As(2)O(3) than the parental K562 cells. As(2)O(3)-induced apoptosis of K562/ADM cells was determined by the observance of typical morphological changes and the appearance of DNA ladder and sub-G1 cell populations. As(2)O(3) significantly inhibited the P-gp expression of K562/ADM cells, and synergistically enhanced the sensitivity of the drug-resistant cells to adriamycin.

CONCLUSIONSAs(2)O(3) induces growth-inhibition and apoptosis, down-regulates P-gp expression and exerts a synergistic effect in combination with adriamycin in multidrug-resistant leukemia cells.

ATP-Binding Cassette, Sub-Family B, Member 1 ; analysis ; Apoptosis ; drug effects ; Arsenicals ; pharmacology ; Drug Resistance, Multiple ; Gene Expression ; Genes, MDR ; Humans ; Leukemia ; genetics ; metabolism ; Oxides ; pharmacology