Targeting c-Jun Is a Potential Therapy for Luminal Breast Cancer Bone Metastasis

Area of Science:

• Oncology
• Molecular Biology
• Cancer Metastasis

Background:

• Luminal breast cancer frequently metastasizes to bone, but mechanisms remain unclear due to limited models.
• Previous development of MCF7-derived bone metastatic cell lines (MCF7-BM) provides a platform for investigation.

Purpose of the Study:

• To characterize MCF7-BM cell lines and identify novel markers for luminal breast cancer bone metastasis.
• To elucidate the role of identified markers in the bone metastatic process and therapeutic potential.

Main Methods:

• Characterization of MCF7-BM cell lines.
• Assessment of c-Jun protein levels and functional impact on cell migration, transformation, and osteolytic activity.
• In vivo studies using dominant-negative c-Jun.
• Analysis of c-Jun expression in bone metastatic lesions.
• Investigation of c-Jun's role in the crosstalk between tumor cells and osteoclasts.
• Pharmacological inhibition of c-Jun using JNK-IN-8.
• Correlation of c-Jun downstream signals with patient prognosis.

Main Results:

• c-Jun protein is upregulated in MCF7-BM cells and promotes tumor cell migration, transformation, and osteolytic ability.
• Inhibition of c-Jun reduced bone metastatic lesions and frequency in vivo.
• c-Jun overexpression creates a vicious cycle with osteoclasts via enhanced calcium-induced migration and BMP5 release.
• JNK inhibitor JNK-IN-8 suppressed tumorigenesis and bone metastasis.
• c-Jun downstream signals correlate with clinical prognosis in luminal breast cancer patients.

Conclusions:

• c-Jun is a novel marker and key mediator of bone metastasis in luminal breast cancer.
• Targeting c-Jun or its signaling pathway presents a potential therapeutic strategy for preventing bone metastasis in this specific breast cancer subtype.