lncRNA BORG:TRIM28 Complexes Drive Metastatic Progression by Inducing α6 Integrin/CD49f Expression in Breast Cancer...

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Triple-negative breast cancer (TNBC) is the most aggressive subtype, characterized by resistance to chemotherapy, metastasis, and recurrence.
• Breast cancer stem cells (BCSCs) drive tumor initiation and aggressive phenotypes through self-renewal and differentiation.
• Understanding the molecular mechanisms governing BCSC tumorigenicity in TNBC is crucial for developing effective therapies.

Purpose of the Study:

• To identify novel molecular regulators of BCSC phenotypes in TNBC.
• To elucidate the role of the long noncoding RNA BORG in TNBC progression.
• To investigate the mechanistic link between BORG, TRIM28, and BCSC-driven tumorigenesis.

Main Methods:

• Correlation analysis of BORG expression with stem cell markers (Nanog, Aldh1a3, Itga6).
• In vitro assays using murine and human TNBC cells to assess BORG's effect on stem cell phenotypes.
• In vivo studies in mice to evaluate BORG's role in TNBC tumor initiation and metastasis.
• Co-immunoprecipitation and chromatin immunoprecipitation assays to determine BORG-TRIM28 interaction and TRIM28 binding at the Itga6 promoter.

Main Results:

• BORG expression positively correlated with stem cell markers Nanog, Aldh1a3, and Itga6.
• BORG enhanced stem cell phenotypes and promoted TNBC tumor initiation in vivo.
• BORG physically interacted with the E3 SUMO ligase TRIM28, promoting BCSC phenotypes.
• TRIM28 binding at the Itga6 promoter was essential for BORG:TRIM28-mediated BCSC self-renewal, expansion, and metastasis.

Conclusions:

• The lncRNA BORG acts as a critical driver of BCSC phenotypes in TNBC.
• BORG promotes aggressive TNBC behaviors, including self-renewal, expansion, and metastasis, via the BORG:TRIM28 complex.
• Targeting the BORG:TRIM28 interaction or downstream effectors like α6 integrin represents a potential therapeutic strategy for TNBC.