Complement Component 3 Adapts the Cerebrospinal Fluid for Leptomeningeal Metastasis

Area of Science:

• Oncology
• Immunology
• Neuroscience

Background:

• Leptomeningeal metastasis (cancer spread to cerebrospinal fluid) is a fatal complication of advanced cancers.
• The mechanisms driving leptomeningeal metastasis remain poorly understood.
• Cancer cells must adapt to the unique cerebrospinal fluid microenvironment.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying leptomeningeal metastasis.
• To identify key factors enabling cancer cell survival and growth in the cerebrospinal fluid.
• To explore therapeutic strategies targeting leptomeningeal metastasis.

Main Methods:

• Utilized lung and breast cancer cell lines with known ability to infiltrate the cerebrospinal fluid.
• Developed preclinical models of leptomeningeal metastasis.
• Quantified complement component 3 (C3) expression in cancer cells and cerebrospinal fluid.
• Investigated the role of C3 in disrupting the blood-cerebrospinal fluid barrier.
• Assessed the therapeutic efficacy of targeting C3 signaling.

Main Results:

• Complement component 3 (C3) was upregulated in leptomeningeal metastatic models and essential for cancer growth in the cerebrospinal fluid.
• Cancer cells within the cerebrospinal fluid produced C3, correlating with disease progression in patients.
• C3 expression in primary tumors predicted leptomeningeal relapse.
• Cancer-derived C3 activated the C3a receptor in the choroid plexus, disrupting the blood-cerebrospinal fluid barrier.
• This disruption allowed plasma-derived mitogens to enter the cerebrospinal fluid, promoting cancer cell proliferation.
• Pharmacologic inhibition of C3 signaling demonstrated therapeutic benefit in preclinical models.

Conclusions:

• Complement component 3 (C3) plays a critical role in facilitating leptomeningeal metastasis.
• C3-mediated disruption of the blood-cerebrospinal fluid barrier is a key mechanism enabling cancer growth in the cerebrospinal fluid.
• Targeting C3 signaling represents a promising therapeutic strategy for managing leptomeningeal metastasis.