[Effect of ultraviolet irradiation on the proliferation of acute promyelocytic leukemia cells under hypoxic conditions and related mechanisms]

OBJECTIVE

To study the effect of 280 nm-LED ultraviolet irradiation on the proliferation of acute promyelocytic leukemia (APL) HL-60 cells under hypoxic conditions and related mechanism.

METHODS

HL-60 cells in the logarithmic growth phase were selected and divided into control, hypoxia, ultraviolet and hypoxia+ultraviolet groups. The cells in the hypoxia group were treated with cobalt chloride (with a final concentration of 150 μmol/L), those in the ultraviolet group were irradiated by 280 nm-LED ultraviolet with an energy intensity of 30 J/m2, and those in the hypoxia+ultraviolet group were treated with cobalt chloride and then irradiated by 280 nm-LED ultraviolet. After 48 hours of treatment, the cells were placed under an invert microscope to observe cell morphology. CCK-8 assay was used to measure the inhibition rate of cell proliferation. Annexin V-FITC/PI double staining flow cytometry was used to evaluate cell apoptosis. Quantitative real-time PCR was used to measure the mRNA expression of Bcl-2. Each experiment above was repeated three times independently.

RESULTS

Compared with the control group, the experimental groups showed shrinkage, decreased brightness, and disordered arrangement of cells, and the number of cells decreased over the time of culture. There were significant differences in the inhibition rate of cell proliferation and cell apoptosis rate among the groups (P<0.01), and the hypoxia+ultraviolet group showed the strongest inhibition of cell proliferation and induction of cell apoptosis, followed by the ultraviolet group and the hypoxia group. Compared with the control group, the other three groups had a gradual reduction in the mRNA expression of Bcl-2, and the hypoxia+ultraviolet group had a significantly greater reduction than the hypoxia and ultraviolet groups (P<0.01).

CONCLUSIONS

Both hypoxia and ultraviolet irradiation can inhibit the proliferation of HL-60 cells and induce cell apoptosis, and ultraviolet irradiation has a better effect on proliferation inhibition and cell apoptosis under hypoxic conditions than under normoxic conditions, possibly by downregulating the mRNA expression of Bcl-2.

[Effect of ultraviolet irradiation on the proliferation of acute promyelocytic leukemia cells under hypoxic conditions and related mechanisms]

OBJECTIVE

To study the effect of 280 nm-LED ultraviolet irradiation on the proliferation of acute promyelocytic leukemia (APL) HL-60 cells under hypoxic conditions and related mechanism.

METHODS

HL-60 cells in the logarithmic growth phase were selected and divided into control, hypoxia, ultraviolet and hypoxia+ultraviolet groups. The cells in the hypoxia group were treated with cobalt chloride (with a final concentration of 150 μmol/L), those in the ultraviolet group were irradiated by 280 nm-LED ultraviolet with an energy intensity of 30 J/m², and those in the hypoxia+ultraviolet group were treated with cobalt chloride and then irradiated by 280 nm-LED ultraviolet. After 48 hours of treatment, the cells were placed under an invert microscope to observe cell morphology. CCK-8 assay was used to measure the inhibition rate of cell proliferation. Annexin V-FITC/PI double staining flow cytometry was used to evaluate cell apoptosis. Quantitative real-time PCR was used to measure the mRNA expression of Bcl-2. Each experiment above was repeated three times independently.

RESULTS

Compared with the control group, the experimental groups showed shrinkage, decreased brightness, and disordered arrangement of cells, and the number of cells decreased over the time of culture. There were significant differences in the inhibition rate of cell proliferation and cell apoptosis rate among the groups (P<0.01), and the hypoxia+ultraviolet group showed the strongest inhibition of cell proliferation and induction of cell apoptosis, followed by the ultraviolet group and the hypoxia group. Compared with the control group, the other three groups had a gradual reduction in the mRNA expression of Bcl-2, and the hypoxia+ultraviolet group had a significantly greater reduction than the hypoxia and ultraviolet groups (P<0.01).

CONCLUSIONS

Both hypoxia and ultraviolet irradiation can inhibit the proliferation of HL-60 cells and induce cell apoptosis, and ultraviolet irradiation has a better effect on proliferation inhibition and cell apoptosis under hypoxic conditions than under normoxic conditions, possibly by downregulating the mRNA expression of Bcl-2.

[Progress in clinical studies of chimeric antigen receptor engineered T cells for treatment of childhood cancer]

Nowadays, the 5-year survival rate of childhood cancer patients can be more than 80%, but some patients with relapse and refractory cancers have shown no good response to traditional strategies. Chimeric antigen receptor engineered T (CAR-T) cell therapy is promising for these patients. CAR-T cells recognize the tumor-associated antigens in a non-major histocompatibility complex-restricted manner, so their anti-tumor ability is enhanced. There are four generations of CAR-T cells now. The complete remission rate of pediatric patients with relapse and refractory acute lymphoblastic leukemia can be as high as 90% when treated with CD19-targeting CAR-T cells. Furthermore, CAR-T cell therapy can also be used to bridge to transplantation and donor CAR-T cell infusion can be a strategy to prevent relapse after hematopoietic stem cell transplantation. As to solid tumors, only patients with neuroblastoma present good response to the GD2-targeting CAR-T cell therapy. The toxic or side effects of CAR-T cell therapy include cytokine release syndrome, off-tumor effect, tumor lysis syndrome, and insertion mutation. Although the CD19-targeting CAR-T cell therapy for childhood cancer can result in a high remission rate, the relapse rate is high, including CD19⁺ and CD19^- relapse. The mechanisms for relapse merit further investigatio.

[Effects of DNA methylation on ABO gene expression in leukemia]

Objective: To investigate the impact of promoter CpG island methylation on ABO mRNA expression in leukemia. Methods: 25 cases of leukemia and 20 cases of normal control were studied, and the leukemia cell lines K562、HL-60 and Jurkat were treated with different concentrations of decitabine. PCR-SSP was used to identify ABO genotype, RQ-PCR for ABO mRNA expression and bisulfite sequencing PCR for DNA methylation status. Results: ① The methylation of ABO promoter in acute myeloid leukemia patients (10 cases) and acute lymphoblastic leukemia patients (10 cases) were 53.85% and 18.22% respectively, which were obviously higher than those in control (20 cases, 2.33%) and chronic myeloid leukemia patients (5 cases, 2.12% ). ② ABO genotype of K562 was O1O1, which has changed little before and after decitabine treatment. ABO genotype of HL-60 and Jurkat could not been identify before treatment, but showed as O1A1 and A1O2 after treatment. ③ABO mRNA expression of K562 was 1 275.67 ± 35.86, which was obviously higher than that in HL-60 (0.54 ± 0.07, P<0.05) and Jurkat (0.82±0.16, P<0.05). ④The methylation of ABO promoter in K562, HL-60 and Jurkat were 0, 58.14%, and 96.74%. As concentration of decitabine increased, the methylation of ABO promoter were decreased and the expressions of ABO mRNA were increased in HL-60 and Jurkat, which had significant differences compared with that before treatment (P<0.05). Conclusion: The methylation of ABO promoter shows a negative correlation with ABO mRNA expression. DNA methylation was an important aspect of ABO antigens decrease in acute leukemia.

[Clinical features and risk factors for infections in adult acute leukemia after chemotherapy]

OBJECTIVE

To observe the clinical characteristics of infections in adult acute leukemia （AL）patients during chemotherapy in hospital, and identify the risk factors for infections.

METHODS

A retrospective study of patients with AL who underwent chemotherapy between July 2010 and Dec 2014 in the First Affiliated Hospital of Xiamen University was conducted. Clinical features and risk factors for infections were analyzed.

RESULTS

191 patients with AL received a total of 728 courses of chemotherapies. During these admissions, 385（52.9%) infections episodes occurred. The common infections sites were lower respiratory tract infection（36.3%，153/374）, bloodstream infection（17.1%, 64/374）, oral infection（13.6%，51/374）, and perianal infection（13.4%, 50/374）. 164 strains of pathogenic bacteria were detected. Gram- negative bacteria were recorded in 59.1% of documented pathogens, and Gram- positive bacteria were responsible for 32.9% of infections. Multivariate unconditioned logistic analysis of factors identified consistent independent risk factors for no completely remission（OR=0.142, P< 0.001）, duration of neutropenia longer than 7 days（OR=12.764, P<0.001）, general wards（OR=1.821, P< 0.001）, and hospitalization interval longer than 10 days（OR=0.720, P=0.039）.

CONCLUSION

Infections after chemotherapy for AL continues to be common. AL patients with induction chemotherapy or severe neutropenia faced an increased risk of infections by multivariate analysis. And patients with short-term stay or laminar flow wards seem to be less susceptible to infections.

Clinical Collaborative Group of Fujian Medical Association Hematological Branch. [Incidence of newly diagnosed adult acute leukemia in Fujian province from 2011 to 2012]

OBJECTIVE

To investigate the incidence of adult (≥14-year-old) acute leukemia (AL) in Fujian Province from 2011 to 2012, based on the survey in 2010.

METHODS

All newly diagnosed adult AL cases were collected during 2011 and 2012 retrospectively, which were registered identically by the clinical collaborative group of Fujian Medical Association Hematological Branch. The group included all the hospitals that could diagnose leukemia.

RESULTS

①We registered 1 551 new adult AL cases totally during 2011 and 2012. The average annual incidence was 2.479/10⁵. 777 new adult AL cases were diagnosed among the whole adult population in Fujian Province in 2011.The crude incidence rate (CIR) was 2.498/105, and age- standardized incidence rate (ASR) was 2.504/10⁵. 774 new adult AL cases were diagnosed in 2012 with 2.460/10⁵ of CIR and 2.455/10⁵ of ASR. No significant changes of the adult AL incidence were found over time during 2011 and 2012. ② During 2011 and 2012, 938 cases of acute myeloid leukemia (AML, non-M) were diagnosed,with 1.499/10⁵ of CIR. 393 cases of acute myeloid leukemia (ALL) with 0.628/10⁵ of CIR, 199 cases of acute promyelocytic leukemia (APL) with 0.318/10⁵ of CIR, 21 cases of the special type with 0.034/10⁵ of CIR. The incidence of AML (non-M) was highest (accounting for 60.48%）, followed by ALL (25.34%）, APL (12.83%）. The special type (1.35%) was the lowest. ③ The survey revealed differences in gender, age, region and season of incidence in Fujian province. The male gender bias of AML and ALL were also observed. The incidence of adult AL increased with age, and reached to the peak in group aged 75-79 (7.081/10⁵）.

CONCLUSION

The incidence of adult AL in Fujian province is in average level in China from 2011 to 2012, according to the leukemia incidence data of International Agency for Research on Cancer (IARC). Compared with the previous national leukemia incidence during 1986 and 1988, the incidence in Fujian is slightly higher. We find no significant changes of the incidence from 2011 to 2012. The constituent ratios of various types of adult AL in Fujian are similar to the previous studies of national incidence rate during 1986-1988.