v-Src Oncogene Induces Trop2 Proteolytic Activation via Cyclin D1

Area of Science:

• Oncology
• Molecular Biology
• Biochemistry

Background:

• Castration-resistant prostate cancer (CRPC) shows enriched Src tyrosine kinase activity in most patients.
• Src signaling influences cyclin D1, a key regulator of poor prognosis in prostate cancer.
• Tumor-associated calcium signal transducer 2 (Trop2) promotes prostate cancer stem cell renewal via proteolytic activation.

Purpose of the Study:

• To investigate the role of Src tyrosine kinase in prostate cancer stem cell (CSC) generation.
• To elucidate the mechanism by which Src induces Trop2 intracellular domain (Trop2 ICD) accumulation.
• To determine the clinical significance of Trop2 ICD and cyclin D1 in prostate cancer progression.

Main Methods:

• v-Src transformation of primary murine prostate epithelial cells.
• Analysis of CSC markers, gene expression, and prostatosphere formation.
• Assessment of Trop2 ICD nuclear localization, proteolytic complex components (PS2, TACE, Numb), and patient survival data.

Main Results:

• v-Src transformation increased CSC proportion, correlating with gene expression and prostatosphere formation.
• Src-induced Trop2 ICD nuclear accumulation was dependent on cyclin D1.
• Cyclin D1 upregulated Trop2 activation components (PS2, TACE) and downregulated Numb, a Trop2 inhibitor.
• Elevated nuclear Trop2 ICD and cyclin D1, with reduced Numb, predicted significantly worse recurrence-free survival in patients (HR=4.35).

Conclusions:

• Cyclin D1 acts as a crucial mediator, linking v-Src activity to Trop2 ICD induction in prostate cancer.
• The Src-cyclin D1-Trop2 axis promotes prostate cancer stemness and predicts poor clinical outcomes.
• Targeting this pathway may offer therapeutic strategies for advanced prostate cancer.