Effects of Vinblastine and Vincristine on the function of chronic myeloid leukemic cells through expression of A20 and CYLD.

Chronic myelogenous leukemia (CML) is characterised by the translocation of regions of the BCR and ABL genes, leading to the fusion gene BCR-ABL forming the Philadelphia (Ph) chromosome. Vinblastine (Vinb) and Vincristine (Vinc) are Vinca alkaloids and frequently used in combination chemotherapy in leukemias and lymphomas. Deubiquitinating enzyme (DUB) genes such as A20, Otubain 1 and CYLD are known as inhibitors of functional activation of immune cells mediated through the NF-κB/STAT pathway. Little is known about the regulatory role of Vinb/Vinc on the function of CML cells and the contribution of the DUBs to those effects. In the end, the gene expression profile was determined by quantitative RT-PCR, physiological properties of CML cells by flow cytometry and cytokine production by ELISA. As a result, inactivated expression of the DUBs A20, CYLD, Otubain 1 and Cezanne and enhanced activation of CD11b+ and CD4T cells were observed in CML patients. Importantly, Vinc enhanced the expression of A20 and CYLD and inhibited the proliferation and survival of CML (K562) cells. The effects were abolished in the presence of A20 siRNA, while cell proliferation only depended on the presence of CYLD. In conclusion, the up-regulation of A20 by Vinc could involve inhibitory effects on the proliferation and survival of K562 cells. The events might contribute to the anticancer effect of Vinc on A20-sensitive CML cells.

CYLD stimulates macrophage phagocytosis of leukemic cells through STAT1 signalling in acute myeloid leukemia.

Acute myeloid leukemia (AML) is the most aggressive hematopoietic malignancy characterized by uncontrolled proliferation of myeloid progenitor cells within the bone marrow. Tumor suppressor cylindromatosis (CYLD) is a deubiquitinating enzyme, which suppresses inflammatory response in macrophages. Macrophages have a central role in the defense against foreign substances and circulating cancer cells by their professional phagocytic capacity. Little is known about contributions of CYLD to changes in biological properties of human macrophages and its involvement in AML. The present study, therefore, explored whether macrophage functions in healthy individuals and AML patients are influenced by CYLD. To this end, ninety-two newly diagnosed AML patients and 80 healthy controls were recruited. The mRNA expression levels of inflammation-related genes were evaluated by real-time PCR, cell maturation, phagocytosis and apoptosis assays by flow cytometry and secretion of inflammatory cytokines by ELISA. As a result, AML patients with the low CYLD expression were significantly higher in M4/M5 than other subtypes according to the FAB type. The low CYLD expression was also closely associated with older patients and enhanced level of LDH in AML. Moreover, treatment of normal macrophages with CYLD siRNA enhanced activation of STAT-1, leading to increases in expressions of maturation markers and IL-6 production as well as suppression in cell apoptosis and phagocytosis, while macrophage phagocytosis from AML M4/M5b was higher than that from healthy controls upon CYLD siRNA transfection through STAT1 signalling. In conclusion, the inhibitory effects of CYLD on macrophage functions are expected to affect the immune response in AML.