Binding to protein by isothiocyanates: a potential mechanism for apoptosis induction in human non small lung cancer...

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Isothiocyanates (ITCs) are known to induce apoptosis, a process often linked to reactive oxygen species (ROS) generation and glutathione depletion.
• The precise molecular mechanisms by which ITCs trigger apoptosis remain incompletely understood.
• Potential mechanisms include binding to macromolecules like DNA and proteins.

Purpose of the Study:

• To investigate the upstream molecular events leading to apoptosis induction by ITCs.
• To determine whether DNA damage or oxidative stress are primary triggers for ITC-induced apoptosis.
• To identify specific protein targets of ITCs and assess their role in apoptosis.

Main Methods:

• Comparative analysis of apoptosis induction, ROS generation, and oxidative damage by Phenethyl isothiocyanate (PEITC) and sulforaphane (SFN) in A549 lung cells.
• Proteomics approach to identify intracellular protein targets of ITCs.
• Assessment of tubulin binding affinity of ITCs and its correlation with apoptosis induction.

Main Results:

• DNA damage was not found to be an early event in ITC-induced apoptosis.
• Sulforaphane (SFN) induced more ROS and oxidative damage than Phenethyl isothiocyanate (PEITC), suggesting oxidative stress is not the primary trigger.
• PEITC showed higher binding affinity to intracellular proteins, with tubulin identified as a key target. ITC binding affinity to tubulin correlated with their potency in inhibiting cell growth and inducing apoptosis.

Conclusions:

• The covalent binding of ITCs to protein targets, particularly tubulin, is a critical event in the induction of apoptosis in human lung A549 cells.
• Apoptosis induction by ITCs is likely mediated by direct protein interactions rather than solely through ROS generation or DNA damage.
• Identifying tubulin as a target provides a specific molecular mechanism for ITC-mediated cytotoxicity.