Lkb1 deletion in periosteal mesenchymal progenitors induces osteogenic tumors through mTORC1 activation

Area of Science:

• Oncology
• Cell Biology
• Biochemistry

Background:

• Osteogenic sarcoma, a bone cancer, has a poor prognosis due to undefined cell of origin and signaling pathways.
• Understanding these factors is crucial for developing effective therapeutic strategies.

Purpose of the Study:

• To identify the cell of origin for osteogenic sarcoma.
• To investigate the role of the LKB1-mTORC1 signaling pathway in osteosarcoma development.
• To evaluate potential therapeutic targets for osteogenic sarcoma.

Main Methods:

• Generated a conditional knockout mouse model by deleting liver kinase b1 (Lkb1) in Cathepsin K (Ctsk)-Cre expressing cells.
• Utilized lineage tracing to identify Ctsk-Cre labeled periosteal cells as mesenchymal progenitors.
• Employed Raptor genetic mouse models and mTORC1 inhibitor treatment to modulate mTORC1 activity.
• Developed xenograft mouse models using human osteosarcoma cell lines.

Main Results:

• LKB1 deficiency in Ctsk+ periosteal cells increased proliferation and osteoblast differentiation.
• Downregulation of mTORC1 activity ameliorated tumor progression in Ctsk-Cre Lkb1fllfl mice.
• LKB1 deficiency promoted tumor formation in human osteosarcoma xenograft models.
• mTORC1 inhibition suppressed xenograft tumor growth.

Conclusions:

• Identified periosteum-derived Ctsk-Cre expressing cells as the cell of origin for osteogenic tumors.
• The LKB1-mTORC1 signaling pathway is implicated in osteosarcoma development.
• Targeting the LKB1-mTORC1 pathway represents a promising therapeutic strategy for osteogenic sarcoma.