[Role of NF-κB inhibitor in Acute Myeloid Leukemia].

OBJECTIVE: To investigate the role of NF-κB inhibitor in occurence and development of AML. METHODS: AML and normal bone marrow samples were collected from 8 AML patients and 8 normal persons. The expression of NF-κB signaling pathway genes was detected by NF-κB PCR array. Then, AML mouse model was constructed to test the role of NF-κB inhibitor in AML. RESULTS: The NF-κB signal pathway was activated in AML patients. The up-regulated genes, EDARADD, TNFSF14, could activate the NF-κB signal pathway, IL6 could regulate the inflammatory signal. The down-regulated genes, TNFRSF 10B, TNFRSF1A, could lead to cell apoptosis. the AML mouse model was constructed successfully. Then administration of NF-κB inhibitor reduced the inhibition of leukemia niche to the normal hematopoietic stem cells (HSCs), promoted the HSC to enter into cell cycle. CONCLUSION: The NF-κB signal pathway is activated in AML cells. AML mouse model is constructed successfully. NF-κB inhibitor has a potential to treat AML and promotes the HSC to enrter into cell cycle.

[Role of Rheb in Human Acute Myeloid Leukemia].

OBJECTIVE: To investigate the role of Rheb (mTOR activator) in AML development by measuring Rheb expression in bone marrow of adult AML patients and in AML cell line HL-60. METHODS: Real-time PCR assay was used to measure the Rheb mRNA expression in 27 AML patients and 29 ITP patients as control. The relationship between Rheb mRNA expression and age, AML subtype, fusion gene, splenomegaly, hepatomegaly and survival of AML patients was analyzed and compared. In addition, HL-60 cell line over-expressing Rheb was established, and the HL-60 cells and HL-60 cells with overexpression of Rheb were treated with Ara-C of different concentrations, the proliferation level was detected by CCK-8 method, and the IC50 was calculated. RESULTS: The mRNA level of Rheb in AML patients was similar to that in ITP patients (control). Interestingly, higher expression of Rheb was associated with better survival and was sensitive to Ara-C treatment. However, the expression level of Rheb was not associated with age, AML subtype, fusion gene, and hepatomegaly of patients. Lower expression level of Rheb was associated with splenomegaly. In vitro analysis of HL-60 line indicated that overexpression of Rheb could increased the cell sensitivity to Ara-C treatment (IC50=0.54 µmol/L) and caused HL-60 cell apoptosis. CONCLUSION: The lower Rheb expression is a poor prognostic indicator for AML patients, which is associated with AML splenomegaly, the patients and HL-60 cells with low expression of Rheb are insensitive to Ara-C treatment.

[Effect of TEB-415, a Derivative of Imatinib, on Multiple Myeloma].

OBJECTIVE: To investigate the growth inhibitory effect of Imatinib derivative TEB-415 on various multiple myeloma (MM) cell lines, such as U226, H929, RPMI8226, MM1R and MM1S. METHODS: TEB-415, a derivative of Imatinib was synthesized by modifying the chemical structure of Imatinib. MM cell lines (U226, H929, RPMI8226, MM1R and MM1S) were treated with TEB-415, Imatini and Bortezomib of various concentrations. Cells were grown for 72 hours and the growth rate was measured by CCK-8 method, cell morphology was observed and the IC50 was calculated. RESULTS: TEB-415 could inhibit H929 and RPMI8226 growth significantly. When the concentration of TEB-415 was <0.1 nmol/L, >50% H929 cells died. The IC50 of Imatinib was 0.123 mol/L while the IC50 of Bortezomib was 0.03 nmol/L. In RPMI8226 cell line, when the concentration of TEB-415 was 11.9 mol/L, more than 50% of cells died. In contrast, when RPMI8266 were treated with Imatinib of the concentration of 12.8 mol/L, cells grew normally. CONCLUSION: In comparison to Imatinib, TEB-415, a derivative of Imatinib, can kill H929 MM cells much effectively, its effecacy is only inferior to Bortezomib. RPMI8226, an MM cell line is insensitive to Imatinib, but still sensitive to TEB-415 and its growth can be inhibited by TEB-415.

[Effects of Rheb overexpression in HL-60 and K562 leukemia cell lines].

mTOR (mammalian target of rapamycin) is the center for cellular activities. It controls many cell activities via inhibiting apoptosis and promoting cell growth. Rheb can activate mTOR signaling pathway and participate in genesis and development of multiple cancers. This study was purposed to explore the underlying role of Rheb in human myeloid leukemia by using the myeloid leukemia cell lines. Two myeloid leukemia cell lines HL-60 and K562 overexpressing Rheb were established with retrovirus containing Rheb. The mRNA and protein expressions of Rheb were determined by Real-Time PCR and Western blot respectively. Cell proliferation rate was examined by CCK-8 assay and apoptosis rate was analyzed using Annexin V and 7-AAD double-staining. The results showed that Rheb was overexpressed in both HL-60 and K562 cell lines. The Rheb overexpression cell lines were successfully established. It is found that overexpression of Rheb could promote cell growth. Furthermore, the overexpression of Rheb could accelerate cells entering into G2/M phase (P < 0.01), while did not affect the apoptosis. It is concluded that Rheb overexpression promotes myeloid leukemia cell proliferation through accelerating cell cycle progression.