OBJECTIVETo construct a eukaryotic expression vector containing aldehyde dehydrogenase-2 (ALDH2) gene and investigate the effects and its possible mechanisms of ALDH2 gene on cell proliferation and anti-oxidative damage in the K562 cells.

METHODSAn eukaryotic expression vector containing the ALDH2 gene cloned from human hepatocytes was constructed and transfected into K562 cells by liposome. RT-PCR and Western blot were used to evaluate the expression of ALDH2. MTT assay was used to check the cell proliferation and trypan blue exclusion to check K562 cells damage induced by hydrogen peroxide (H2O2). RT-PCR and fluorescence spectrophotometry were used to determine the expression of heme oxygenase-1 (HO-1) and the generation of intracellular reactive oxygen species (ROS) respectively.

RESULTSRT-PCR and Western blot analysis showed distinct higher ALDH2 protein expression in gene transfected group. The latter group had a higher cell proliferation (P < 0.05) and survival rate against H2O2 induced-oxidative damage, being increased by 7.8 times (IC(50) was 12.3 µmol/L and 1.4 µmol/L for K562-pcDNA3.1-ALDH2 and control cells, respectively, P < 0.01). The HO-1 mRNA expression and the generation of intracellular ROS were downregulated at a specific concentration of H2O2 in the ALDH2 gene transfected group.

CONCLUSIONALDH2 gene transfection can protect K562 cells against oxidative damage, and the downregulation of HO-1 expression and intracellular ROS may be involved in this process.

Aldehyde Dehydrogenase ; Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; Humans ; Hydrogen Peroxide ; K562 Cells ; RNA, Messenger ; genetics ; Transfection

OBJECTIVETo investigate the effect of heme oxygenase-1 (HO-1) expression on cell growth and apoptosis in imatinib resistant chronic myeloid leukemia (CML) cells (K562/A02-IM), and explore the relationship between HO-1 gene and CML.

METHODSThe expression of HO-1 in 20 drug-resistant CML patients was detected by RT-PCR. Different concentrations of hemin were used to induce HO-1 expression of K562/A02-IM, HO-1 expression at different time was detected by RT-PCR and Western blot analysis. Cell apoptosis was detected by Annexin V/PI staining, and MTT assay was used to detect viability of K562/A02-IM cells after induction or inhibition of HO-1 gene by hemin and zinc protoporphyrin (ZPP).

RESULTSRT-PCR showed that HO-1 was expressed in the bone marrow mononuclear cells (BMMNCs). When treated with hemin at different concentrations (0, 10, 20, 40 µmol/L) for 16 h, the expression of HO-1 in K562/A02-IM was increased in a dose-dependent manner, and peaked at 20 µmol/L of hemin for 16 h. The apoptosis rates were (17.61 ± 0.01)%, (12.13 ± 0.11)%, (7.94 ± 0.03)% and (4.62 ± 0.15)% at 0,10, 20 and 40 µmol/L of hemin respectively for 16 h and were (14.7 ± 0.05)%, (8.1 ± 0.07)% and (16.3 ± 0.13)% at 20 µmol/L of hemin treatment for 8,16, and 24 h respectively. Hemin induced apoptosis of K562/A02-IM cells in a dose-dependent manner. The expression of HO-1 was induced in K562/A02-IM cells in a dose-dependent manner, and the survival of K562/A02-IM cells was significantly increased as compared to that of control group. When HO-1 was inhibited by ZPP, the cells survival was sharply decreased compared to that of the control group (P < 0.05).

CONCLUSIONHO-1 was expressed in the BMMNCs. It is a kind of molecules whose expression can be induced and can promote the growth of drug-resistant cells. Inhibition of HO-1 expression probably be used for the treatment of drug-resistant CML.

Antineoplastic Agents ; pharmacology ; Benzamides ; Cell Cycle ; Cell Proliferation ; drug effects ; Drug Resistance, Neoplasm ; drug effects ; genetics ; Heme Oxygenase-1 ; genetics ; Humans ; Imatinib Mesylate ; K562 Cells ; Piperazines ; pharmacology ; Pyrimidines ; pharmacology

Objective To develop attenuated Salmonella which harboring enterovirus 71 (EV71) VPI gene. Methods The plasmid which expressed VP1 protein of EV71 was constructed by gene recombination. Cellular expression was assessed by Western Blot analysis. The recombinant plasmid was then transformed into attenuated Salmonella SL7207. Results EV71 VP1 gene sequence was inserted into a eukaryotic expression plasmid VR1012. VP1 protein was detected by Western Blot analysis in the culture supernatant. And the attenuated Salmonella harbored the plasmid stable. Conclusion The plasmid was constructed successfully and it can express effectively in vitro. The bacteria which harboring the plasmid were constructed successfully. This has provided a basis for further research of an oral EV71 vaccine.

Spontaneous remission (SR) of leukemia is a rare event in clinic, which possibly correlated with severe infection and sepsis, but its exact mechanism has not been confirmed. Plasmacytoid dendritic cells (pDC) and myeloid dendritic cells (mDC) play a key role in innate and adaptive immunity respectively. A patient with severe infection of staphylococcus aureus acquired completely spontaneous remission (SR), moreover a increased number of pDC were observed, suggesting that bacteria-activated pDC may play an important role in SR. This study was purposed to explore if the bacteria can stimulate pDC successfully and get a functional pDC. Both pDC and mDC were isolated from freshly collected, leukocyte-rich buffy coats from healthy blood donor and leukemic patient with SR by using MACS and FACS. The pDC were cultured in RPMI 1640 medium and were stimulated with different kinds of bacteria and the expression of CD40, CD86 and HLA-DR on the cell surface was analyzed by flow cytometry. The cytokine (IFN-α, IL-12, IFN-γ, IL-2, IL-4, IL-10) production was measured by using ELISA kits. The results showed that the stimulation with staphylococcus aureus and pseudomonas aeruginosa resulted in the maturation of pDC, which secrete a large number of IFN-α and promote the differentiation of naive CD4⁺ T cells to Th1 cells. The activated pDC expressed high level of CD40 and CD86 and showed higher T cell stimulatory capacities. It is concluded that staphylococcus aureus and pseudomonas aeruginosa can activate pDC, the activated pDC secrete high quantity of IFN-α. This result suggests that bacteria stimulated pDC may play a key role in SR of leukemia following severe infections.
CD4-Positive T-Lymphocytes ; Dendritic Cells ; immunology ; microbiology ; Humans ; Interferon-alpha ; Interleukin-10 ; Interleukin-12 ; Interleukin-2 ; Interleukin-4 ; Leukemia ; diagnosis ; immunology ; microbiology ; Remission, Spontaneous ; Staphylococcus aureus