Cyclooxygenase 2 mediates the antiangiogenic effect of rapamycin in Ewing sarcoma

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Rapamycin demonstrates anti-tumor and anti-angiogenic properties in various cancers.
• Cyclooxygenase 2 (COX-2) plays a role in tumor angiogenesis.
• The study investigates if rapamycin's anti-angiogenic effects are mediated by COX-2 suppression.

Purpose of the Study:

• To evaluate the efficacy of rapamycin in inhibiting tumor growth and angiogenesis in Ewing sarcoma (ES).
• To determine the effect of rapamycin on Cyclooxygenase 2 (COX-2) expression in ES.
• To explore the potential mechanism of rapamycin's anti-angiogenic action in ES.

Main Methods:

• Ewing sarcoma xenografts were established in mice and treated with rapamycin.
• Tumor vascularity was assessed using lectin perfusion angiography and immunohistochemistry.
• COX-2 protein and messenger RNA (mRNA) levels were quantified, alongside Western blot analysis for specific pathway proteins.

Main Results:

• Rapamycin treatment significantly reduced tumor weight and blunted tumor vascularity.
• While p70s6k and Akt phosphorylation remained unaffected, COX-2 protein and mRNA levels were suppressed.
• Tumor growth inhibition and reduced angiogenesis were observed in rapamycin-treated xenografts.

Conclusions:

• Low-dose rapamycin effectively inhibits tumor growth and angiogenesis in human Ewing sarcoma.
• The anti-angiogenic effect of rapamycin in ES may be mediated by the suppression of Cyclooxygenase 2 (COX-2).
• Rapamycin's mechanism in ES does not appear to involve the inhibition of p70s6k and Akt phosphorylation.