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RepSox slows decay of CD34+ acute myeloid leukemia cells and decreases T cell immunoglobulin mucin-3 expression.

ABSTRACT: Despite initial response to therapy, most acute myeloid leukemia (AML) patients relapse. To eliminate relapse-causing leukemic stem/progenitor cells (LPCs), patient-specific immune therapies may be required. In vitro cellular engineering may require increasing the "stemness" or immunogenicity of tumor cells and activating or restoring cancer-impaired immune-effector and antigen-presenting cells. Leukapheresis samples provide the cells needed to engineer therapies: LPCs to be targeted, normal hematopoietic stem cells to be spared, and cancer-impaired immune cells to be repaired and activated. This study sought to advance development of LPC-targeted therapies by exploring nongenetic ways to slow the decay and to increase the immunogenicity of primary CD34(+) AML cells. CD34(+) AML cells generally displayed more colony-forming and aldehyde dehydrogenase activity than CD34(-) AML cells. Along with exposure to bone marrow stromal cells and low (1%-5%) oxygen, culture with RepSox (a reprogramming tool and inhibitor of transforming growth factor-β receptor 1) consistently slowed decline of CD34(+) AML and myelodysplastic syndrome (MDS) cells. RepSox-treated AML cells displayed higher CD34, CXCL12, and MYC mRNA levels than dimethyl sulfoxide-treated controls. RepSox also accelerated loss of T cell immunoglobulin mucin-3 (Tim-3), an immune checkpoint receptor that impairs antitumor immunity, from the surface of AML and MDS cells. Our results suggest RepSox may reduce Tim-3 expression by inhibiting transforming growth factor-β signaling and slow decay of CD34(+) AML cells by increasing CXCL12 and MYC, two factors that inhibit AML cell differentiation. By prolonging survival of CD34(+) AML cells and reducing Tim-3, RepSox may promote in vitro immune cell activation and advance development of LPC-targeted therapies.

SUBMITTER: Jajosky AN

PROVIDER: S-EPMC4073822 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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RepSox slows decay of CD34+ acute myeloid leukemia cells and decreases T cell immunoglobulin mucin-3 expression.

Jajosky Audrey N AN Coad James E JE Vos Jeffrey A JA Martin Karen H KH Senft Jamie R JR Wenger Sharon L SL Gibson Laura F LF

Stem cells translational medicine 20140522 7

Despite initial response to therapy, most acute myeloid leukemia (AML) patients relapse. To eliminate relapse-causing leukemic stem/progenitor cells (LPCs), patient-specific immune therapies may be required. In vitro cellular engineering may require increasing the "stemness" or immunogenicity of tumor cells and activating or restoring cancer-impaired immune-effector and antigen-presenting cells. Leukapheresis samples provide the cells needed to engineer therapies: LPCs to be targeted, normal hem ...[more]

PMID: 24855276

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Project description:BackgroundAcute myeloid leukemia (AML) is an immunophenotypically heterogeneous malignant disease, in which CD34 positivity is associated with poor prognosis. CD34+ AML cells are 10-15-fold more resistant to daunorubicin (DNR) than CD34- AML cells. Curcumin is a major component of turmeric that has shown cytotoxic activity in multiple cancers; however, its anti-cancer activity has not been well studied in DNR-insensitive CD34+ AML cells. The aim of this study was to therefore to explore curcumin-induced cytotoxicity in DNR-insensitive CD34+ AML cell lines (KG1a, Kasumi-1), DNR-sensitive U937 AML cells, and primary CD34+ AML bone-marrow-derived cells.MethodsPrimary human CD34+ cells were isolated from peripheral blood mononuclear cells or bone marrow mononuclear cells using a CD34 MicroBead kit. The growth inhibitory effects of curcumin were evaluated by MTT and colony-formation assays. Cell cycle distribution was examined by propidium iodide (PI) assay. Apoptosis was analyzed by Wright-Giemsa, Hoechst 33342 and Annexin-V/PI staining assays. The change in mitochondrial membrane potential (MMP) was examined by JC-1 staining and flow cytometry. Expression of apoptosis-related proteins was determined by reverse transcription-polymerase chain reaction and Western blotting. Short interfering RNA (siRNA) against Bcl-2 was used in CD34+ KG1a and Kasumi-1 cells incubated with/without DNR.ResultsCurcumin inhibited proliferation and induced apoptosis and G1/S arrest in both DNR-insensitive KG1a, Kasumi-1 and DNR-sensitive U937 cells. Curcumin-induced apoptosis was associated with reduced expression of both Bcl-2 mRNA and protein, subsequent loss of MMP, and activation of caspase-3 followed by PARP degradation. Curcumin synergistically enhanced the cytotoxic effect of DNR in DNR-insensitive KG1a and Kasumi-1 cells, consistent with decreased Bcl-2 expression. Accordingly, siRNA against Bcl-2 increased the susceptibility of KG1a and Kasumi-1 cells to DNR-induced apoptosis. More importantly, curcumin suppressed Bcl-2 expression, selectively inhibited proliferation and synergistically enhanced the cytotoxicity of DNR in primary CD34+ AML cells, while showing limited lethality in normal CD34+ hematopoietic progenitors.ConclusionCurcumin down-regulates Bcl-2 and induces apoptosis in DNR-insensitive CD34+ AML cell lines and primary CD34+ AML cells.

Dataset Information

RepSox slows decay of CD34+ acute myeloid leukemia cells and decreases T cell immunoglobulin mucin-3 expression.

Publications

RepSox slows decay of CD34+ acute myeloid leukemia cells and decreases T cell immunoglobulin mucin-3 expression.

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