Stanniocalcin 1 is overexpressed in multipotent mesenchymal stromal cells from acute myeloid leukemia patients.

Objectives: Multipotent mesenchymal stromal cells (MSC) play a pivotal role in the bone marrow (BM) niche. Stanniocalcin 1 (STC1) secreted by MSC has been demonstrated to promote the survival of neoplastic cells and was suggested a marker for minimal residual disease of acute myeloid leukemia (AML). Therefore, we evaluated the expression of STC1 in MSC from AML patients (MSCAML) compared to MSC from healthy donors (MSCHD).Methods: Liquid culture assays of MSCAML and MSCHD were performed to compare expansion capacity. Gene expression profiles of MSCAML vs. MSCHD were established. Secretion of STC1 was tested by ELISA in MSCAML vs. MSCHD and expression of STC1 in AML- vs. HD-BM by immunohistochemistry. In addition, co-cultures of AML cells on MSC were initiated and ultrastructural intercellular communication patterns were investigated. Finally, the effect of blocking STC1 on AML cells was evaluated.Results: MSCAML showed significant decreased expansion capacity compared to MSCHD. Gene analysis revealed marked overexpression of STC1 in MSCAML. ELISA and immunohistochemical findings confirmed this observation. Electron microscopy analysis showed reciprocal stimulation between AML cells and MSC. Blockade of STC1 did not significantly affect AML cell proliferation and apoptosis.Discussion: Characteristics of MSC differ depending on whether they originate from AML patients or from HD. STC1 was mostly overexpressed in MSCAML compared to MSCHD. In vitro blockade of STC1, however, was not associated with AML cell proliferation and apoptosis.Conclusion: Differences in expression levels of glycoproteins from MSCAML compared to MSCHD not necessarily assume that these molecules are niche-relevant in leukemic disease.

A new exon 12 mutation in the EPAS1 gene possibly associated with erythrocytosis.

In secondary erythrocytosis, the elevated red cell count is powered by factors outside the erythroid compartment, for instance by raised erythropoietin (EPO) synthesis based on congenital defects of the oxygen-sensing pathway. The principal transcriptional regulator of EPO synthesis is endothelial PAS domain-containing protein 1 (EPAS 1). We present here the first report of a patient with erythrocytosis involving a mutation of amino acid 525 in EPAS1. The p.Asp525His mutation affects a residue that is farthermost from primary functional site Pro-531 of any of the erythrocytosis-related mutations that have been identified up to now.

Low-dose trofosfamide plus rituximab is an effective and safe treatment for diffuse large B-cell lymphoma of the elderly: a single center experience.

BACKGROUND: Rituximab plus combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) is broadly accepted as standard for the treatment of diffuse large B-cell lymphoma (DLBCL). Nevertheless, there is sparsely data concerning the management of elderly patients. METHODS: We performed a retrospective study of treatment with rituximab and low-dose trofosfamide in elderly patients (≥ 75 years) with DLBCL who were not suitable for R-CHOP or R-CHOP-like regimens or who did not consent to aggressive treatment. The choice regarding the qualification for R-CHOP or R-CHOP-like regimen was left to the estimation of the treating physicians. RESULTS: Eleven patients with a median age of 83 years (range, 75-90 years) were included. The age-adjusted international prognostic index was low risk in one patient, low-intermediate in four patients, high-intermediate in three patients, and high risk in 3 patients. All patients were evaluable for response. Five patients (45%) achieved a complete response, three (27%) a partial response, one (9%) stable disease, and two (18%) progressive disease. The estimated 1-yr overall survival was 54.5%, and the estimated 1-yr progression-free survival 45.5%, however, three patients (27%) were alive without evidence of disease at 16-20 months from start of treatment. Main toxicity was leukopenia (36% grade III or IV), whereas grade III/IV non-hematological adverse events did not occur. CONCLUSIONS: Due to its potency and low toxicity, trofosfamide/rituximab might represent an alternative therapy for DLBCL of elderly patients not suitable for R-CHOP. This observation, however, should be confirmed in a larger patient population within a prospective clinical trial.

TGF-ß1 and CXCL12 modulate proliferation and chemotherapy sensitivity of acute myeloid leukemia cells co-cultured with multipotent mesenchymal stromal cells.

OBJECTIVES: Multipotent mesenchymal stromal cells (MSCs) play a central role within the bone marrow (BM) niche, supporting hematopoiesis via soluble factors like cytokines and chemokines. In our study, we sought to investigate the effect of blocking transforming growth factor beta 1 (TGF-ß1) and C-X-C motif chemokine 12 (CXCL12) receptor CXCR4 on acute myeloid leukemia (AML) cells in an MSC co-culture system. METHODS: Human MSCs were obtained by BM aspirates and their phenotype and functional properties were confirmed in vitro. Co-cultures of AML cells on MSCs were initiated and compared to those on mouse fibroblasts (MS-5) and liquid cultures. Additionally, the effect of blocking CXCR4 and TGF-ß1 on AML cells was tested with and without the addition of cytarabine. RESULTS: MSCs from BM showed a typical phenotype and differentiation pattern. Co-culture of AML cells on MSCs resulted in a significantly higher proliferation capacity than on MS-5 or liquid culture. Blockade of TGF-ß1 increased AML cell proliferation and chemosensibility, while the CXCR4 antagonist plerixafor showed anti-proliferative effects and did not change cytarabine-induced cell death compared to control. DISCUSSION: Human MSCs are potent feeder cells, able to maintain AML cells in long-term culture. This favorable co-existence seems to be due in part to molecules important for communication within the niche. Blockade of TGF-ß1 and CXCL12 was associated with different effects on AML cell proliferation and chemotherapy resistance. CONCLUSION: These findings suggest a strong supporting affinity between MSCs and AML cells within the leukemic niche, where TGF-ß1 and CXCL12 pathways play an important role.