Targeting the protein kinase C family: are we there yet?

Area of Science:

• Molecular Biology
• Cancer Research
• Pharmacology

Background:

• Protein kinase C (PKC) is a family of serine/threonine kinases crucial for cell signaling pathways, including proliferation, differentiation, apoptosis, and angiogenesis.
• Dysregulation of PKC signaling is frequently observed in tumorigenesis and contributes to cancer drug resistance.
• The diverse roles of individual PKC isozymes within different cellular contexts and tumor types create complexity in therapeutic strategies.

Approach:

• Reviewing the complex roles of individual PKC isozymes in cancer development and drug resistance.
• Analyzing reasons for the failure of early clinical trials involving PKC inhibitors, including those combined with cytotoxic drugs.
• Evaluating recent negative Phase III trial outcomes for PKC inhibitors in non-small-cell lung cancer.

Key Points:

• PKC isozymes have distinct functions, making broad inhibition strategies problematic.
• Early clinical trials of PKC inhibitors showed limited efficacy and significant toxicity.
• Recent large-scale trials in non-small-cell lung cancer have also failed to demonstrate clinical benefit.

Conclusions:

• The complexity of PKC isozyme function necessitates a more nuanced approach to therapeutic targeting.
• Understanding the specific roles of each isozyme in different cancers is critical for developing effective treatments.
• Further research is needed to identify predictive biomarkers and optimize therapeutic strategies for targeting PKC in cancer.