Single-Cell Transcriptomic Analysis Identifies Senescent Osteocytes That Trigger Bone Destruction in Breast Cancer...

Area of Science:

• Oncology
• Cell Biology
• Bone Biology

Background:

• Breast cancer bone metastases are a significant cause of morbidity, increasing fracture risk and mortality.
• Tumor cell colonization of the bone microenvironment disrupts the osteoblast-osteoclast balance, leading to bone lesions.

Purpose of the Study:

• To investigate the role of osteocytes in the bone microenvironment during breast cancer metastasis.
• To understand the cellular mechanisms underlying bone destruction in breast cancer bone metastases.

Main Methods:

• Single-cell RNA sequencing of osteocytes from mice with bone metastases.
• Multiplex in situ hybridization and AI-assisted analysis in mice and human patients.
• In vitro and ex vivo organ cultures to assess breast cancer cell-induced osteocyte senescence.
• Treatment with senolytics to clear senescent cells.

Main Results:

• Osteocytes in established breast cancer bone metastases exhibit premature senescence and a senescence-associated secretory phenotype (SASP).
• Senescent osteocytes express pro-osteoclastogenic genes, favoring bone resorption.
• Breast cancer cells induce osteocyte senescence and enhance their osteoclastogenic potential.
• Senolytic treatment reduced bone resorption and preserved bone mass in preclinical models.

Conclusions:

• Breast cancer cells reprogram osteocytes, inducing pathological senescence and a SASP that drives bone destruction.
• Osteocyte senescence is an initiating event in the development of lytic bone disease associated with breast cancer metastases.
• Targeting senescent osteocytes with senolytics offers a potential therapeutic strategy to mitigate bone loss in metastatic breast cancer.