p53 and its downstream proteins as molecular targets of cancer

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genetics

Background:

• The p53 tumor suppressor gene is vital for preventing tumor formation via transcriptional regulation, inducing growth arrest and apoptosis.
• Mutations in the p53 gene occur in over 50% of human cancers, leading to therapy resistance by hindering p53-mediated apoptosis.
• Strategies to target p53 include restoring its wild-type conformation, disrupting Mdm2-p53 binding, inhibiting Mdm2 ligase activity, and identifying novel drug targets within p53 signaling pathways.

Purpose of the Study:

• To identify novel therapeutic targets within the p53 signaling pathway that modulate p53-induced apoptosis.
• To characterize genes regulated by p53 in a lung cancer model to find potential drug targets.

Main Methods:

• Gene expression profiling of a p53 temperature-sensitive lung cancer cell model using Affymetrix human HG-U133 GeneChip.
• Identification of thousands of genes induced or repressed by p53-induced apoptosis.
• Characterization of SAK (Snk/Plk-akin kinase), a p53-repressed gene, using small interfering RNA (siRNA) for silencing and overexpression studies.

Main Results:

• Thousands of unique genes were identified as either induced or repressed in response to p53-induced apoptosis.
• SAK (Snk/Plk-akin kinase), a polo-like kinase family member, was identified as a p53-repressed gene.
• SAK silencing using siRNA induced apoptosis, while SAK overexpression attenuated p53-induced apoptosis, confirming SAK repression by p53 contributes to apoptosis.

Conclusions:

• SAK repression by p53 is a key mechanism contributing to p53-induced apoptosis.
• SAK represents a promising cancer drug target for developing novel apoptosis-inducing anticancer therapies.
• Future research will focus on normal cell responses to SAK silencing to establish a therapeutic window for potential SAK inhibitors.