LAUSR

BACKGROUND Kaurane-type diterpenoids, obtained from various natural sources, have shown many biological activities, including anti-inflammatory and antitumor effects. Caracasine (Fig 1), an ent-kaurane diterpenoid isolated from the flowers of Croton micans, was shown to induce apoptosis in leukaemia cell lines. OBJECTIVE The present study aimed to ascertain the compound's mechanism of cell death induction using two leukaemia cell lines, Jurkat E6.1 (T cell) and HL-60 (promyeloblast cells). METHODS Cell death in Jurkat and HL60 cells was evaluated by flow cytometry for apoptosis with annexin-V/PI, mitochondrial membrane potential disturbance, changes in cell cycle, CD95 expression, caspase activation, Nuclear Factor kappa B inhibition, and differentiation into a neutrophil-like cell (dHL60). RESULTS Caracasine (10 µM) increased the G0/G1 phase in Jurkat and arrested the cell cycle in the S phase in HL60. Caracasine increased CD95 expression (p<0.01 in Jurkat and p<0.05 in HL60) and caspase-8 activation (p <0.001 in Jurkat and p<0.05 in HL60). Caspase-9 was activated in both cell lines (p<0.001) along with the decline in mitochondrial ΔΨm (p<0.05 in Jurkat and p<0.001 in HL60). In HL60 cells, the kaurane induced neutrophil differentiation, assessed by CD40 expression and reactive oxygen species production. In Jurkat cells, caracasine inhibited the NF-κB pathway in cells pretreated with PHA to activate the NF-κB pathway, suggesting a possible role in inflammatory diseases. CONCLUSION Caracasine induced apoptosis through the intrinsic and extrinsic pathway in both cell lines evaluated and may be an important leader structure for new anti-leukemic and anti-inflammatory drugs.