ICB3E induces iNOS expression by ROS-dependent JNK and ERK activation for apoptosis of leukemic cells

Area of Science:

• Molecular Biology
• Cell Biology
• Pharmacology

Background:

• c-Jun N-terminal Kinase (JNK) and extracellular signal-regulated kinase (ERK) are involved in cellular stress responses and apoptosis.
• Hydroxychavicol (HCH), derived from Piper betle, induces apoptosis.
• ICB3E, a synthetic HCH analogue, demonstrated anti-chronic myeloid leukemia (CML) activity previously.

Purpose of the Study:

• To elucidate the mechanism of action of ICB3E in inducing apoptosis in leukemic cells.
• To compare the potency of ICB3E and HCH in inducing apoptosis.
• To investigate the specific signaling pathways involved in ICB3E-mediated cell death.

Main Methods:

• Treatment of K562 leukemic cells with ICB3E and HCH.
• Measurement of reactive oxygen species (ROS) accumulation.
• Analysis of JNK, ERK, iNOS, caspase 9, caspase 3, and PARP activation.
• Assessment of nitric oxide (NO) generation.
• Investigation of apoptosis pathways (intrinsic vs. extrinsic) using specific antibodies and blocking agents.

Main Results:

• ICB3E is 3-4 times more potent than HCH in inducing apoptosis of leukemic cells, with minimal effects on normal cells.
• ICB3E treatment leads to early accumulation of mitochondria-derived ROS in K562 cells.
• ICB3E induces ROS-dependent activation of JNK and ERK, upregulates iNOS, and generates NO.
• This pathway results in caspase 9, caspase 3, and PARP cleavage, indicating intrinsic pathway-mediated apoptosis.
• Extrinsic pathway markers (caspase 8, DR5, Fas) were not involved.

Conclusions:

• ICB3E triggers leukemic cell apoptosis through a novel reactive oxygen species (ROS)-dependent pathway.
• This pathway involves the activation of JNK/ERK, subsequent iNOS induction, and nitric oxide (NO)-mediated cell death.
• ICB3E represents a promising therapeutic agent for CML, acting via the intrinsic apoptotic pathway.