Huiping Sun

Eriocalyxin B induces apoptosis of t(8;21) leukemia cells through NF-|[kappa]|B and MAPK signaling pathways and triggers degradation of AML1-ETO oncoprotein in a caspase-3-dependent manner

Diterpenoids isolated from Labiatae family herbs have strong antitumor activities with low toxicity. In this study, Eriocalyxin B (EriB), a diterpenoid extracted from Isodon eriocalyx, was tested on human leukemia/lymphoma cells and murine leukemia models. Acute myeloid leukemia cell line Kasumi-1 was most sensitive to EriB. Significant apoptosis was observed, concomitant with Bcl-2/Bcl-XL downregulation, mitochondrial instability and caspase-3 activation. AML1-ETO oncoprotein was degraded in parallel to caspase-3 activation. EriB-mediated apoptosis was associated with NF-κB inactivation by preventing NF-κB nuclear translocation and inducing IκBα cleavage, and disturbance of MAPK pathway by downregulating ERK1/2 phosphorylation and activating AP-1. Without affecting normal hematopoietic progenitor cells proliferation, EriB was effective on primary t(8;21) leukemia blasts and caused AML1-ETO degradation. In murine t(8;21) leukemia models, EriB remarkably prolonged the survival time or decreased the xenograft tumor size. Together, EriB might be a potential treatment for t(8;21) leukemia by targeting AML1-ETO oncoprotein and activating apoptosis pathways.

The 12-year follow-up of survival, chronic adverse effects, and retention of arsenic in patients with acute promyelocytic leukemia

To the editor: Arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) have demonstrated notable success in the treatment of acute promyelocytic leukemia (APL).[1][1][⇓][2]-[3][3] However, few studies have reported the adverse effects (AEs), long-term toxicity, and secondary carcinogenesis of

All-trans retinoic acid and arsenic combination therapy benefits low-to-intermediate-risk patients with newly diagnosed acute promyelocytic leukaemia: a long-term follow-up based on multivariate analysis

All-trans retinoic acid (ATRA) and chemotherapy have enabled great improvements in the treatment of acute promyelocytic leukaemia (APL). High initial white blood cell (WBC) and low platelet counts are generally considered as independent risk factors for APL (Sanz et al, 2000). However, the relapse rate has been reported to be as high as 5–30% (Tallman, 2007). In 2001, a pilot clinical trial was held at Shanghai Institute of Haematology to treat APL with ATRA and arsenic combination therapy (Shen et al, 2004), and the 5-year follow-up (Hu et al, 2009) showed high efficacy. Since then, this approach has been shown not to be inferior to or even better than ATRA and chemotherapy. In the present study, we updated the follow-up to clarify the long-term survival and the risk factors in APL patients when using the ATRA and arsenic combination therapy. Between February 2001 and July 2010, 217 newly diagnosed APL patients were included in this study. Informed consent was obtained in all patients. The criteria for diagnosis, cytogenetic analysis and molecular tests for PML-RARA transcripts were performed as previously described (Shen et al, 2004), together with the treatment protocol (Table SI). Briefly, for induction therapy, all patients received ATRA and arsenic until documented complete remission (CR). Idarubicin (IDA) was given in case of high-risk patients. Three courses of consolidation therapy followed induction. The maintenance therapy consisted of 5 cycles of sequential use of ATRA, arsenic and low-dose chemotherapy (6-mercaptop-

Treatment of Acute Promyelocytic Leukemia with Arsenic Trioxide

Fifty three cases of acute promyelocytic leukemia (APL) patients, including 43 relapsed and 10 primary cases, were evaluated as to the effectiveness of As203 treatment. Clinical complete remission (CR) was obtained in 40 out of 43 (93%) patients in the relapsed group. Two of the three non-responders studied showed clonal evolution at relapse. In a follow-up of 33 cases for 1 to 42 months, the estimated disease-free survival (DFS) rates for 1- and 2- years were 62.4% and 36.7%, respectively and the actual median DFS was 11 months. Patients presenting white blood cells (WBC) count below 10X109/L at relapse showed better survival than those with WBC count over 10X109/L (p=0.044). Clinical outcome was related to post-remission therapy, since there was only 2 relapse out of 11 cases in combination therapy group, compared to 11 out of 18 with As203 treatment alone (p=0.01). Meanwhile, eight out of 10 (80%) primary cases achieved clinical CR. However, six out of 10 primary patients had elevated plasma liver transaminase levels and two died with severe hepatic toxicity, in contrast to the mild liver dysfunction in one fourth of the patients with relapsed APL. RT-PCR analysis in both relapsed and de novo groups showed that induction using As203 over short period of time was not sufficient to eliminate minimal residual disease. Long-term use of the drug could, nevertheless, lead to a molecular remission at least in some patients. We thus recommend that ATRA should be used as first line remission induction in de novo APL, while As203 can be either used as a rescue for relapsed cases, or included into multi-drug consolidation/maintenance clinical trials.

Inactivation of PBX3 and HOXA9 by down-regulating H3K79 methylation represses NPM1-mutated leukemic cell survival

Acute myeloid leukemia (AML) with an NPM1 mutation (NPMc+) has a distinct gene expression signature and displays molecular abnormalities similar to mixed lineage leukemia (MLL), including aberrant expression of the PBX3 and HOXA gene cluster. However, it is unclear if the aberrant expression of PBX3 and HOXA is essential for the survival of NPM1-mutated leukemic cells. Methods: Using the gene expression profiling of TCGA and E-MTAB-3444 datasets, we screened for high co-expression of PBX3 and HOXA9 in NPMc+ leukemia patients. We performed NPMc+ depletion and overexpression experiments to examine aberrant H3K79 methylation through epigenetic regulation. Through RNA interference technology and small-molecule inhibitor treatment, we evaluated the effect of methyl-modified H3K79 on cell survival and explored the possible underlying mechanism. Results: We showed that NPMc+ increased the expression of PBX3 and HOXA9, which are both poor prognosis indicators in AML. High PBX3 and HOXA9 expression was accompanied by increased dimethylated and trimethylated H3K79 in transgenic murine Lin-Sca-1+c-Kit+ cells and human NPMc+ leukemia cells. Using chromatin immunoprecipitation sequencing (ChIP-seq) assays of NPMc+ cells, we determined that hypermethylated H3K79 was present at the expressed HOXA9 gene but not the PBX3 gene. PBX3 expression was positively regulated by HOXA9, and a reduction in either PBX3 or HOXA9 resulted in NPMc+ cell apoptosis. Importantly, an inhibitor of DOT1L, EPZ5676, effectively and selectively promoted NPMc+ human leukemic cell apoptosis by reducing HOXA9 and PBX3 expression. Conclusion: Our data indicate that NPMc+ leukemic cell survival requires upregulation of PBX3 and HOXA9, and this action can be largely attenuated by a DOT1L inhibitor.