Navitoclax Combined with Daunorubicin Promotes Apoptosis of Erythroleukemia Cell Lines K562, HEL and TF-1 / 中国实验血液学杂志

OBJECTIVE@#To study the effect of apoptotic drug Navitoclax (NTX) combined with chemotherapy drug Daunorubicin (DNR) on apoptosis of erythroleukemia cells.@*METHODS@#K562, HEL and TF-1 cells in logarithmic growth phase were treated with NTX, DNR and combination of the two drugs. CCK-8 test, Annexin V-DAPI double-staining flow cytometry, real-time RT-PCR were used to detect cell growth, cell apoptosis and expression of BAX, BAK, BCL-2, BCL-xl and BIM respectively. The effects of NTX, DNR and combination of the two drugs on apoptosis of K562, HEL and TF-1 cells were compared and analyzed.@*RESULTS@#NTX combined with DNR could significantly inhibit the growth of K562, HEL and TF-1 cells; Apoptosis detection results showed that the apoptotic rate of K562, HEL and TF-1 cells in combination group was significantly higher than that in NTX and DNR single group; the expression level of apoptosis-related genes BAK and BAX in K562 cells in combination group was significantly higher than that in two single drug groups, and the expression level of anti-apoptotic protein genes BCL-2 and BCL-xl was significantly lower than that in two single drug groups (P＜0.05); the expression level of BAK in HEL cells treated with combined drugs for 24 hours was higher than that in DNR group (P ＜ 0.05); the expression level of BCL-2 in TF-1 cells treated with combined drugs for 24 hours was lower than that in two single drugs groups while the expression level of BAK in 48 hours was the highest in combined drugs group, and the expression level of BCL-2 and BCL-xl in combined drugs group was lower than that in NTX group (P＜0.05).@*CONCLUSION@#NTX combined with DNR can significantly promote the apoptosis of erythroleukemia cell lines K562, HEL and TF-1, and induce the expression of apoptosis-related genes. This study provides a new scheme for the clinical treatment of erythroleukemia.

Clinical features and gene mutation spectrum in children with sideroblastic anemia / 中国当代儿科杂志

OBJECTIVE@#To study the clinical features and gene mutation spectrum of children with sideroblastic anemia (SA) and the clinical value of targeted next-generation sequencing in the molecular diagnosis of children with SA.@*METHODS@#Clinical data were collected from 36 children with SA. Targeted next-generation sequencing was used to detect mutations in SA-related pathogenic genes and genes associated with heme synthesis and mitochondrial iron metabolism. The association between genotype and clinical phenotype was analyzed.@*RESULTS@#Of the 36 patients, 32 had congenital sideroblastic anemia (CSA) and 4 had myelodysplastic syndrome with ring sideroblasts (MDS-RS). Mutations in CSA-related genes were detected in 19 children (19/36, 53%), among whom 9 (47%) had ALAS2 mutation, 4 (21%) had SLC25A38 mutation, and 6 (32%) had mitochondrial fragment deletion. No pathogenic gene mutation was detected in 4 children with MDS-RS. Among the 19 mutations, 89% (17/19) were known mutations and 11% (2/19) were novel mutations. The novel mutation of the ALAS2 gene c.1153A>T(p.I385F) was rated as "possibly pathogenic" and the novel mutation of the SLC25A38 gene c.175C>T(p.Q59X) was rated as "pathogenic".@*CONCLUSIONS@#ALAS2 and SLC25A38 gene mutations are commonly seen in children with CSA, but mitochondrial gene fragment deletion also accounts for a relatively high proportion. For children with hypoplastic anemia occurring in infancy, mitochondrial disease should be considered.

ADAR1 Knockout Inhibits Notch1-induced T-ALL in Mice / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the effect of ADAR1 on the occurrence and development of mouse T cell acute lymphoblastic leukemia (T-ALL).</p><p><b>METHODS</b>Lck-Cre; ADAR1lox/lox mice were generated through interbreeding. The lineage-cells of Lck-Cre; ADAR1lox/lox mice and the control were enriched respectively by the means of MACS, and the lin- cells were transfected with retrovirus carrying MSCV-ICN1-IRES-GFP fusion gene. Then the transfection efficiency was detected by the means of FACS, and the same number of GFP+ cells were transplanted into lethally irradiated recipient mice to observe the survival of mice in 2 recipient group after transplantation.</p><p><b>RESULTS</b>T cell-specific knockout ADAR1 mice were generated, and Notch1-induced T-ALL mouse model was established successfully. The leukemia with T-ALL characteristics occured in the mice of control group, but did not in the ADAR1 kmockout mice after transplantation.</p><p><b>CONCLUSIONS</b>ADAR1 plays a key role in the incidence and development of Notch1-induced T-ALL.</p>

Knockdown of Larp4b in Lin(-) cells does not affect the colony forming ability of mouse hematopoietic cells / 中国实验血液学杂志

Larp4b is a member of the LARP family, which can interact with RNA and generally stimulate the translation of mRNA. Abnormal expression of Larp4b can be found in leukemia patients in our previous study. This study was purposed to detect the relative expression of Larp4b mRNA in different subpopulations of mouse hematopoietic cells, to construct lentivirus vector containing shLarp4b targeting mouse gene Larp4b and to explore its effects on mouse Lin(-) cells infected with shLarp4b by lentivirus. SF-LV-shLarP4b-EGFP and control vectors were constructed and two-plasmid lentivirus packing system was used to transfect 293T cells. After 48 h and 72 h, lentivirus SF-LV-shLarp4b-EGFP was harvested and was used to infect Lin(-) cells. After 48 h, EGFP(+) cells was sorted by flow cytometry (FCM). Meanwhile, semi-quantitative real time-PCR, AnnexinV-PE/7-AAD staining, PI staining and colony forming cell assay (CFC) were performed to determine the expression of Larp4b and its effect on the proliferation of hematopoietic progenitor cells. The results showed that Larp4b was highly expressed in myeloid cells. SF-LV-shLarp4b-EGFP was successfully constructed according to the restriction endonuclease digestion assay. RT-PCR confirmed that Larp4b was efficiently knockdown in mouse Lin(-) cells. The low expression of Larp4b did not affect the colony forming number, the apoptosis and cell cycle of Lin(-) cells. It is concluded that knockdown of Larp4b in mouse Lin(-) cells do not contribute to the colony forming ability and the growth of Lin(-) cells in vitro. This useful knockdown system will be used to study in vivo Larp4b in future.

Recent studies on PI3K/AKT/mTOR signaling pathway in hematopoietic stem cells / 中国实验血液学杂志

PI3K/AKT/mTOR signaling pathway plays an essential role in the growth, proliferation and survival of various type of cells and also hematopoietic stem cells (HSC). Aberrant activation of PI3K/AKT/mTOR signaling pathway leads to exhaustion of HSC, while the inhibition of PI3K/AKT/mTOR signaling pathway results in blocking of B cell differentiation. This article reviews the latest advances on the role of key components involved in the PI3K/AKT/mTOR signaling pathway, including PI3K, AKT, mTOR, FoxO and GSK-3 in HSC.

Effects of Rheb overexpression in HL-60 and K562 leukemia cell lines / 中国实验血液学杂志

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.

Regulatory mechanisms of PI3K/AKT signaling pathway in acute leukemia / 中国实验血液学杂志

This study was aimed to analyze the expression profiles of PI3K/AKT signaling pathway genes from bone marrow samples of AML and ALL patients and normal samples. AML, ALL and normal bone marrow samples were collected from 6 AML, 6 ALL patients and 4 normal persons. The expression of PI3K/AKT signaling pathway genes including PTEN, CCND1, mTOR, RICTOR, FOXO1 were detected by real-time fluorescent quantification RT-PCR while GAPDH gene expression was used as an internal reference. The relative gene expression level was calculated by the method of the 2(-ΔΔCt). The results showed that the gene expression profiles were different between normal and leukemic groups. PTEN, mTOR and RICTOR expression levels were down-regulated, while FOXO1 and CCND1 levels were up-regulated in AML and ALL. PTEN was down-regulated in 10 out of the 12 samples; mTOR was down-regulated in 9 out of the 12 samples; RICTOR was down-regulated in 7 out of the 12 samples; FOXO1 was up-regulated in 9 out of the 12 samples and CCND1 was up-regulated in 7 out of the 12 samples. It is concluded that PI3K/AKT signal pathway is activated in both AML and ALL leukemic cells.