Discrete functions of GSK3α and GSK3β isoforms in prostate tumor growth and micrometastasis

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• The specific roles of glycogen synthase kinase-3 alpha (GSK3α) and glycogen synthase kinase-3 beta (GSK3β) isoforms in cancer remain unclear.
• Understanding isoform-specific functions is crucial for targeted cancer therapies.

Purpose of the Study:

• To elucidate the distinct roles of GSK3α and GSK3β in prostate cancer progression.
• To investigate the impact of GSK3 isoform silencing on cancer cell proliferation, survival, migration, and metastasis.

Main Methods:

• Utilized short hairpin RNA (shRNA) to silence GSK3α and GSK3β expression in prostate cancer cell lines (PC3, DU145, LNCaP).
• Assessed effects on cell proliferation, apoptosis, colony formation, migration, and invasion in vitro.
• Evaluated tumor growth and micrometastasis in PC3 xenograft models in athymic nude mice.
• Analyzed molecular mechanisms including apoptosis markers, β-catenin, and epithelial-to-mesenchymal transition (EMT) markers.

Main Results:

• Silencing GSK3α, but not GSK3β, significantly inhibited prostate cancer cell proliferation, survival, and tumor xenograft growth, while enhancing apoptosis.
• Both GSK3α and GSK3β silencing equally reduced prostate cancer cell migration, invasion, and in vivo lung micrometastasis.
• GSK3α silencing increased pro-apoptotic markers (cleaved caspase-3, cleaved caspase-9).
• GSK3β silencing inhibited cell scattering, promoted cell-cell contacts, increased β-catenin expression and membrane localization, and reduced EMT markers (Snail, MMP-9), indicating a role in EMT and invasiveness.

Conclusions:

• GSK3α and GSK3β exhibit distinct, isoform-specific functions in prostate cancer.
• GSK3α primarily influences proliferation, survival, and apoptosis.
• GSK3β plays a critical role in epithelial-to-mesenchymal transition, cell motility, and invasive potential, suggesting it as a potential therapeutic target for metastasis.