Identification of amino acids essential for the antiangiogenic activity of tumstatin and its use in combination antitumor activity

Abstract

Tumstatin is an angiogenesis inhibitor that binds to ␣v␤3 integrin and suppresses tumor growth. Previous deletion mutagenesis studies identified a 25-aa fragment of tumstatin (tumstatin peptide) with in vitro antiangiogenic activity. Here, we demonstrate that systemic administration of this tumstatin peptide inhibits tumor growth and angiogenesis. Site-directed mutagenesis identified amino acids L, V, and D as essential for the antiangiogenic activity of tumstatin. The tumstatin peptide binds to ␣v␤3 integrin on proliferating endothelial cells and localizes to select tumor endothelium in vivo. Using 3D molecular modeling, we identify a putative interaction interface for tumstatin peptide on ␣v␤3 integrin. The antitumor activity of the tumstatin peptide, in combination with bevacizumab (anti-VEGF antibody), displays significant improvement in efficacy against human renal cell carcinoma xenografts when compared with the single-agent use. Collectively, our results demonstrate that tumstatin peptide binds specifically to the tumor endothelium, and its antiangiogenic action is mediated by ␣v␤3 integrin, and, in combination with an anti-VEGF antibody it exhibits enhanced tumor suppression of renal cell carcinoma.angiogenesis ͉ ␣v␤3 integrin ͉ bevacizumab ͉ tumstatin peptide

Tylophorine, a phenanthraindolizidine alkaloid isolated from Tylophora indica exerts antiangiogenic and antitumor activity by targeting vascular endothelial growth factor receptor 2–mediated angiogenesis

“…Angiogenesis, the formation of new blood vessels by sprouting from pre-existing endothelium [1], one of the characteristic of malignant neoplasia development [2]. Angiogenesis blockade has been shown to be an effective strategy in inhibiting tumor growth and metastasis [3].…”

Novel Peptide-Specific Quantitative Structure–Activity Relationship (QSAR) Analysis Applied to Collagen IV Peptides with Antiangiogenic Activity

“…These results are consistent with a previous study on the tumstatin peptide by Eikesdal et al . 35 They found that the mutations to the NINN region resulted in a significant change in EC proliferation inhibition. These results also indicate that truncations to the 20-mer peptide with the exception of the phenylalanine in the 20 th position would be detrimental to the activity of the collagen IV derived peptides.…”

Inhibition of angiogenesis by a synthetic fusion protein VTF derived from vasostatin and tumstatin

“…Similarly, studies in a number of human tumor models have shown that the combination of two distinct angiogenesis inhibitors, vasostatin and interleukin-12, mediates stronger antitumor activity than individual treatment [11]. It has also been reported that the combination of SU5416, VEGFR2 tyrosine kinase inhibitor and low-dose endostatin [12], or anti-VEGF antibody bevacizumab (Avastin) with tumstatin [13], provided enhanced efficacy for suppression of tumor growth than monotherapy alone. Cocktail therapy has been proved to be highly effective in the treatment of malignant diseases such as cancer and AIDS [14].…”