FRMD8 inhibits tumor metastasis in BRCA1-associated TNBC by negatively regulating tmTNF-α

Area of Science:

• Oncology
• Molecular Biology
• Cancer Metastasis Research

Background:

• Triple-negative breast cancer (TNBC) presents limited therapeutic options and poor prognosis, especially with metastasis.
• BRCA1-mutant breast cancer cells are a significant subtype of TNBC with high metastatic potential.
• Understanding the molecular mechanisms driving TNBC metastasis is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the role of FERM domain-containing protein 8 (FRMD8) in the metastatic potential of BRCA1-mutant TNBC.
• To elucidate the molecular pathways through which FRMD8 influences tumor cell metastasis.
• To identify potential therapeutic targets for inhibiting TNBC metastasis.

Main Methods:

• Library screening and in vivo animal experiments to identify key molecular players.
• Functional assays to determine the impact of FRMD8 expression on tumor cell behavior.
• Analysis of the interaction between FRMD8, transmembrane TNF-α (tmTNF-α), and inactive rhomboid protein 2 (iRHOM2) using molecular pathway analysis.

Main Results:

• Low expression of FRMD8 significantly enhances the metastatic potential of BRCA1-mutant TNBC cells.
• FRMD8 deficiency inhibits tmTNF-α cleavage and promotes surface expression of tmTNF-α.
• FRMD8 regulates tmTNF-α by inhibiting iRHOM2 degradation via the endocytic pathway.
• Combined low FRMD8 and iRHOM2 expression strongly facilitates in vivo TNBC metastasis.
• Paclitaxel and etanercept combination treatment reversed FRMD8 and iRHOM2 expression, inhibiting metastasis in vivo.

Conclusions:

• FRMD8 plays a critical role in regulating TNF-α processing and TNBC metastasis.
• The FRMD8/iRHOM2/tmTNF-α axis represents a novel molecular pathway involved in TNBC progression.
• Targeting the FRMD8/iRHOM2 pathway, potentially with combined therapies like paclitaxel and etanercept, shows promise for inhibiting TNBC metastasis.