Reversing the Paradigm: Protein Kinase C as a Tumor Suppressor

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Protein kinase C (PKC) was long considered an oncoprotein due to its interaction with tumor promoters.
• Decades of clinical trials using PKC inhibitors in cancer have yielded poor results, sometimes with adverse effects.

Purpose of the Study:

• To re-evaluate the role of PKC in cancer based on recent genetic and clinical findings.
• To challenge the established dogma of PKC as an oncoprotein and explore its tumor-suppressive functions.

Main Methods:

• Analysis of cancer-associated mutations across the PKC family in various cancer types.
• Review of clinical trial outcomes for PKC inhibitor-based cancer therapies.
• Examination of germline loss-of-function mutations in PKC isozymes linked to lymphoproliferative disorders.

Main Results:

• PKC isozymes are frequently inactivated in cancer, indicating a tumor-suppressive role.
• Clinical trials inhibiting PKC have consistently failed and sometimes harmed patients.
• Germline loss-of-function mutations in PKC are associated with lymphoproliferative disorders.

Conclusions:

• PKC functions as a tumor suppressor, contrary to previous beliefs.
• Cancer treatment strategies should shift from inhibiting PKC to restoring its function.