Studies on HOXB4 expression during differentiation of human cytomegalovirus-infected hematopoietic stem cells into lymphocyte and erythrocyte progenitor cells

HOXA5 inhibits adipocytes proliferation through transcriptional regulation of Ccne1 and blocking JAK2/STAT3 signaling pathway in mice

The highly regulated proliferation of adipocytes plays a momentous role in fat development and obesity. Hoxa5 is an important member of Hox family, its encoded protein is an important transcription factor related to development. And its differential expression in different adipose tissues seems to indicate that Hoxa5 may be involved in the regulation of adipocyte proliferation. In order to evaluate the regulation mechanism of Hoxa5 on adipocyte proliferation, we constructed a variety of Hoxa5 expression vectors in vivo and in vitro to explore its mechanism on adipocyte proliferation and its potential impact on obesity. We have observed that the overexpression of Hoxa5 strongly reduces cell counts, and Hoxa5 can inhibit cell proliferation and block cell cycle progression by regulating the expression of genes such as Cyclin E, Cycling D1 and p53. Most importantly, we demonstrated that Hoxa5 exerts its effect by regulating the signaling pathway of Janus kinase 2 (JAK2) signal transduction and transcription 3 (STAT3) activator, as well as binding to the promoter region of Ccne1 and inhibiting the transcription of Ccne1.This study provides an in-depth understanding of the potential molecular mechanism of Hoxa5 inhibiting adipocyte proliferation. Our results suggest the importance of Hoxa5 in the treatment of obesity.

HOXB4 promotes the malignant progression of ovarian cancer via DHDDS

Background

Homeobox B4 (HOXB4) is correlated with poor prognosis of various cancer types. However, how HOXB4 promotes ovarian cancer (OV) progression remains unclear.

Methods

The Cancer Genome Atlas (TCGA) database indicated that a high level of HOXB4 in OV was correlated with poor prognosis. The biological functions of HOXB4 were confirmed by colony formation, migration, and invasion assays. The effect of HOXB4 on the expression of EMT cell markers was determined. The transcriptional target of HOXB4 was DHDDS, which was detected by a ChIP assay. A xenograft tumor model was generated in nude mice to detect the role of HOXB4 in tumor proliferation and metastasis.

Results

The results showed that HOXB4 protein levels were higher in OV tissues than in normal tissues and correlated with poor prognosis of OV. HOXB4 reduction inhibited the proliferation and invasion ability of OV cells in vitro. Conversely, these effects were enhanced by the upregulation of HOXB4 in OV cells. The binding of HOXB4 to two DNA motifs regulated DHDDS expression and contributed to the malignant progression of OV. The role of HOXB4 in contributing to tumor development in vivo was verified in mice. Further results indicated that HOXB4 induced Snail and Zeb1 expression.

Conclusion

Overall, HOXB4 overexpression was remarkably correlated with poor prognosis of OV. Mechanistically, HOXB4 enhances the proliferation and invasion of tumor cells by activating DHDDS, thereby promoting the malignant progression of OV.

Effect of ATRA on the expression of HOXA5 gene in K562 cells and its relationship with cell cycle and apoptosis

Leukemia is the most common malignant disease in children with high incidence and mortality rates, and a poor treatment effect. The aim of the present study was to examine the changes in the expression of homeobox (Hox) A5 gene and its relationship with cell cycle and apoptosis through the intervention of human K562 myeloid leukemia cell line by all-trans retinoic acid (ATRA), to analyze the role of HOXA5 in the pathogenesis and development process of myeloid leukemia. The optimal concentration of ATRA to be used with K562 cells was determined using a cell counting kit-8 (CCK-8). After 24, 72 and 48 h following treatment of K562 cells with 10 µmol/l ATRA, cell cycle events and apoptosis were measured using flow cytometry. HOXA5 mRNA and protein expression in K562 cells was assessed by RT-PCR and western blot analysis, and the relationship between HOXA5 expression and cell cycle and apoptosis was analyzed. The HOXA5 mRNA and protein expression levels were increased following treatment with ATRA in K562 cells. Apoptosis was increased significantly. The cell cycle was inhibited in G0/G1 phase. Cell proliferation was also inhibited. HOXA5 mRNA and protein expression rates positively correlated with cell apoptosis and the increased percentage and cell cycle of the G0/G1 phase. However, HOXA5 negatively correlated with the reduced percentage of S stage. In conclusion, the expression of HOXA5 in cells was increased following treatment with ATRA in K562 cells, in a time-dependent manner. Additionally, ATRA may inhibit the proliferation of K562 cells and promote apoptosis by upregulating the HOXA5 mRNA and protein expression.

Effect of silencing HOXA5 gene expression using RNA interference on cell cycle and apoptosis in Jurkat cells

Acute lymphocytic leukemia (ALL) is a common malignant tumor with a high morbidity rate among children, accounting for approximately 80% of leukemia cases. Although there have been improvements in the treatment of patients frequent relapse lead to a poor prognosis. The aim of the present study was to determine whether HOXA5 may be used as a target for gene therapy in leukemia in order to provide a new treatment. Mononuclear cells were extracted from the bone marrow according to the clinical research aims. After testing for ALL in the acute stage, the relative mRNA and protein expression of HOXA5 was detected in the ALL remission groups (n=25 cases per group) and the control group [n=20 cases, immune thrombocytopenia (ITP)]. Gene silencing by RNA interference (RNAi) was used to investigate the effect of silencing HOXA5 after small interfering RNA (siRNA) transfection to Jurkat cells. The HOXA5-specific siRNA was transfected to Jurkat cells using lipofectamine. The experiment was divided into the experimental group (liposomal transfection of HOXA5 targeting siRNA), the negative control group (liposomal transfection of cells with negative control siRNA) and the control group (plus an equal amount of cells and culture media only). Western blotting and quantitative fluorescent polymerase chain reaction (QF‑PCR) were used to detect the relative HOXA5 mRNA expression and protein distribution in each cell group. Cell distribution in the cell cycle and the rate of cells undergoing apoptosis were determined using flow cytometry. The expression of HOXA5 at the mRNA and protein levels in the acute phase of ALL was significantly higher than that in ALL in the remission and control groups. In cells transfected with HOXA5-specific siRNA, the expression of HOXA5 at the mRNA and protein levels decreased significantly (P<0.05). The distribution of cells in the cell cycle was also altered. Specifically, more cells were present in the G0/G1 phase compared to the S phase (P<0.05). In addition, the apoptotic rate was significantly higher in cells transfected with HOXA5‑specific siRNA (P<0.05). In conclusion, high expression levels of HOXA5 mRNA and protein in children with ALL indicate that HOXA5 is closely associated with childhood ALL. In addition, HOXA5-specific siRNA effectively silences HOXA5 gene expression and induces apoptosis and cell-cycle arrest in Jurkat cells, thus inhibiting cell proliferation.