Silencing HDAC3 Enhances Apoptosis of Acute B Lymphoblastic Leukemia Cells smurf2 Inducing By Inhibiting JAK/STAT3 Signal Pathway

Purpose Smad ubiquitin regulatory factor 2(Smurf2) as a member of ubiquitinated E3 ligase was certificated to regulate the ubiquitination level of target gene. In this study, smurf2 as tumor suppressor was studied in acute B lymphoblastic leukemia, Histone deacetylases 3(HDAC3) which was connected with smurf2 was related with poor prognosis. It is further proved that smurf2 and HDAC3 were expected to be therapeutic targets for B-ALL cells and improve the prognosis of patients with B-ALL.

Methods Realtime-PCR and westernblot were used to detect the expression of smurf2 and HDAC3 in healthy donors and B-ALL patients by us. Sup-B15 and CCRF-SB were treated with MG-132, small interfering RNA of smurf2 or HDAC3. Up-regulating smurf2 plasmid was also transfected to B-ALL cells by lipo3000. Flow cytometry and westernblot were used to validate the difference of apoptosis and cell cycle.

Results Smurf2 mRNA in B-ALL patients was significantly lower than that in healthy donors. HDAC3 was higher in B-ALL patients than that in healthy donors. Protein level of smurf2 and HDAC3 was consistent with mRNA level. Up-regulating smurf2 by plasmid or MG-132 and silencing smurf2 could influence HDAC3, which further depressed JAK/STAT3 signal pathway inducing apoptosis of B-ALL cells. Sup-B15 and CCRF-SB were treated with siHDAC3 and MG-132 for 24h, we discovered that silencing HDAC3 enhanced the apoptosis level of B-ALL cells MG-132 inducing by depressing JAK/STAT3 pathway. It was expected to become a therapeutic target for improving the clinical prognosis of B-ALL patients. On the other hand, we found that MG-132 caused G2/M phase arrest in B-ALL cells and successfully inhibited the JAK/STAT3 pathway leading to apoptosis.

Conclusions Silencing HDAC3 inhibited the JAK/STAT3 pathway and further enhanced apoptosis in B-ALL cells MG-132 inducing. HDAC3 and smurf2 were expected to become therapeutic targets for clinical treatment of acute B lymphocytic leukemia and improve survival rate of leukemia patients.

Key words Smurf2; HDAC3; Apoptosis; Prognosis;