Organogenesis and angiogenin

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Angiogenesis, the formation of new blood vessels, is crucial for tumor growth.
• Human colon adenocarcinoma cells (HT-29) conditioned medium was screened for angiogenesis-inducing factors.
• The 'organizer' hypothesis inspired the search for these factors.

Purpose of the Study:

• To isolate and characterize an angiogenesis-inducing factor from HT-29 cell conditioned medium.
• To investigate the properties, structure-function relationship, and therapeutic potential of the isolated factor, named angiogenin.
• To explore angiogenin inhibition as a strategy for cancer treatment.

Main Methods:

• Isolation of angiogenin from conditioned medium.
• Biochemical and structural analysis of angiogenin, comparing it to ribonuclease A (RNase A).
• In vitro and in vivo studies using angiogenin inhibitors (monoclonal antibody, actin) to assess their effect on angiogenesis and tumor growth.

Main Results:

• Angiogenin, a 14 kD protein homologous to RNase A, was isolated as a potent angiogenesis stimulator.
• Angiogenin exhibits low enzymatic activity but possesses a critical cell binding site essential for angiogenesis.
• Inhibitors of angiogenin, including a monoclonal antibody and actin, effectively blocked angiogenesis in vitro and suppressed tumor growth in vivo.
• Tumor growth inhibition was observed in HT-29 xenografts and tumors derived from other human cell lines.

Conclusions:

• Angiogenin is a key mediator of angiogenesis with therapeutic potential for cancer treatment.
• Inhibition of angiogenin's activity presents a viable strategy for combating malignant diseases.
• Non-cytotoxic inhibitors like actin demonstrate significant anti-tumor effects without observable toxicity.