Role of NF-kappaB in p53-mediated programmed cell death

Area of Science:

• Molecular Biology
• Cancer Research
• Cellular Signaling

Background:

• The p53 tumor suppressor is critical for inhibiting cell growth via cell-cycle arrest and apoptosis.
• Mutations in p53 or defects in its induction are common in many cancers.
• Nuclear factor-kappa B (NF-kappaB) is a key transcription factor modulating apoptotic responses.

Purpose of the Study:

• To investigate the relationship between p53 induction and NF-kappaB activation in the context of apoptosis.
• To determine the role of NF-kappaB in p53-mediated cell death.
• To elucidate the signaling pathway involved in p53-induced NF-kappaB activation.

Main Methods:

• Induction of p53 in cancer cells.
• Assessment of NF-kappaB activation.
• Inhibition of NF-kappaB activity and MEK1.
• Analysis of apoptosis induction.

Main Results:

• p53 induction activated NF-kappaB, correlating with apoptosis.
• NF-kappaB is essential for p53-induced apoptosis; its inhibition abrogated cell death.
• p53-mediated NF-kappaB activation involved MEK1 and pp90rsk, distinct from TNF-alpha.
• MEK1 inhibition blocked NF-kappaB activation and p53-induced cell death.

Conclusions:

• NF-kappaB is essential for p53-mediated apoptosis.
• The pathway involves MEK1 and pp90rsk.
• Inhibiting NF-kappaB in wild-type p53 tumors might decrease therapeutic response.