Synergistic interactions between differentiation-inducing agents in inhibiting the proliferation of HL-60 human myeloid leukaemia cells in clonogenic micro assays

Abstract

All-trans-retinoic acid, hexamethylene bisacetamide and 5-azacytidine are inducers of granulocytic differentiation of HL-60 human myeloid leukaemic cells, which eventually leads to inhibition of cell proliferation. The effect of graded concentrations of all-trans-retinoic acid (RA) (1 nM-1 microM), hexamethylene bisacetamide (HMBA) (0.5-4 mM) and/or 5-azacytidine (5azaC) (1 nM-1 mM), alone and in combination with each other on colony formation and growth of HL-60 cells was studied in agar capillary clonogenic micro assays in order to identify new potential therapeutic regimens for elderly patients with acute myeloid leukaemia. ED90 concentrations, inducing 90% inhibition of colony formation for RA, HMBA and 5azaC, were 128 nM, 2.7 mM and 40 microM, respectively. The drug interactions between these differentiating agents were analysed by Berenbaum's general algebraic solution. The combinations: RA + HMBA, 5azaC + HMBA and RA + 5azaC were significantly synergistic in inhibiting HL-60 colony formation. Their interaction indices were 0.62, 0.83, and 0.97, respectively, at a specific effect level of 15%. The addition of 1 mM HMBA to 100 nM 5azaC- and 1 nM RA-treated cultures significantly increased the colony-formation inhibition from only 2.6% and 7.0% to 46.4%, and 43.1%, respectively. Also, HMBA showed marked synergism with RA and 5azaC in inhibiting colony growth. The interaction indices (I) of HMBA + RA and HMBA + 5azaC were 0.013 and 0.009, respectively, at the same specific level of 15%. Moreover, the triple combination of RA + HMBA + 5azaC showed synergism in inhibiting both the colony formation (I = 0.7) and colony growth (I = 0.4) at the same specific level of 15%. Since RA, HMBA and 5azaC were effective when administered alone in phase I clinical trials of myeloid leukaemic patients, their synergistic combinations could provide shorter and less toxic courses of treatment in elderly myeloid leukaemic patients. I is less than 1, = 1 or greater than 1 in synergistic, additive or antagonistic interactions, respectively.

Enthalpic Interaction Coefficients of N,N′-Hexamethylenebisacetamide in Aqueous Glucose and Sucrose Solutions at 298.15 K

“…6,7 Also, HMBA is usually used to cooperate with other antitumor drugs to get a better effect on differentiation. 8,9 However, so far the induced differentiation mechanism of HMBA is not demonstrated clearly. On the other hand, glucose and sucrose are important biological substances in the bodies of animals and plants, and hence the drug getting into living body most probably interacts with the sugars.…”

“…To humans, cancer is the second killer in all types of diseases. Research on various cancers and antitumor drugs has been ongoing for years. − Among various antitumor drugs, N , N ′-hexamethylenebisacetamide (HMBA), a small polar molecule compound, cannot only induce differentiation of leukemia cells but also could lead to a variety of tumor cells to normal differentiation. , At the present, people have done a series of research on the function of HMBA to Burkitt lymphoma Raji cells, malignant pleural mesothelioma, and so forth. , Also, HMBA is usually used to cooperate with other antitumor drugs to get a better effect on differentiation. , However, so far the induced differentiation mechanism of HMBA is not demonstrated clearly. On the other hand, glucose and sucrose are important biological substances in the bodies of animals and plants, and hence the drug getting into living body most probably interacts with the sugars.…”

5-aza-2′-deoxycytidine promotes migration of acute monocytic leukemia cells via activation of CCL2-CCR2-ERK signaling pathway

“…In the current study, the level of differentiation of 5-Aza-induced THP-1 cells was determined by microscopy and by assessing the expression levels of CD14. The results indicated that 5-Aza produces a similar biological effect on cell differentiation in THP-1 cells to different types of AML cell lines (12,20). 5-Aza is hypothesized to induce differentiation by inhibiting DNA methylation and upregulating the expression of transcription factors associated with differentiation.…”

“…Several studies have reported that 5-Aza exerts a number of effects in different leukemia cell lines, including inhibition of cell proliferation and induction of differentiation (6,12). THP-1, a monocytic leukemia cell line driven by the MLL-AF9 fusion gene, was employed for the purposes of the present study.…”

“…A previous study demonstrated that 5-Aza induces differentiation and growth inhibition of HL60 human promyelocytic leukemia cells (12). THP-1 cells, which are driven by the mixed-lineage leukemia (MLL)-ALL1-fused gene from chromosome 9 (AF9) fusion gene, are derived from the M5 subtype of AML, and are different to HL60 cells in a number of respects, including the regulation of gene expression, signaling pathway involvement and pathogenesis.…”