A Screen for Extracellular Signal-Regulated Kinase-Primed Glycogen Synthase Kinase 3 Substrates Identifies the p53...

Area of Science:

• Oncology
• Virology
• Molecular Biology

Background:

• Kaposi's sarcoma-associated herpesvirus (KSHV) drives malignancies like primary effusion lymphoma (PEL).
• The KSHV LANA protein promotes cancer cell growth and survival by modulating cellular kinases, including ERK and GSK-3.
• Understanding LANA's kinase interactions is crucial for developing targeted therapies against KSHV-driven cancers.

Purpose of the Study:

• To identify cellular proteins phosphorylated by ERK and GSK-3 in the context of KSHV infection.
• To investigate the role of identified substrates, specifically iASPP, in PEL cell survival and apoptosis.
• To evaluate iASPP inhibition as a potential therapeutic strategy for KSHV-associated malignancies.

Main Methods:

• Protein microarray screening to identify ERK-primed GSK-3 substrates.
• Mass spectrometry and cotransfection assays to validate iASPP as a substrate and assess its degradation.
• Treatment of PEL cells with an iASPP inhibitor, alone and in combination with Nutlin-3, to assess apoptosis induction.

Main Results:

• Identified 58 potential ERK-primed GSK-3 substrates, with iASPP confirmed as a target.
• GSK-3 mediates the degradation of iASPP, which normally inhibits p53-induced apoptosis.
• Inhibition of iASPP induced apoptosis in KSHV-infected PEL cells, an effect additive with Nutlin-3.

Conclusions:

• iASPP is a key mediator of KSHV-driven cell survival by antagonizing apoptosis.
• Targeting iASPP represents a promising therapeutic approach to sensitize KSHV-positive PEL cells to cell death.
• This study reveals a novel mechanism by which KSHV promotes oncogenesis and identifies a potential vulnerability.