The synthetic peptide P111-136 derived from the C-terminal domain of heparin affin regulatory peptide inhibits tumour growth of prostate cancer PC-3 cells.

Abstract

BACKGROUND:

Heparin affin regulatory peptide (HARP), also called pleiotrophin, is a heparin-binding, secreted factor that is overexpressed in several tumours and associated to tumour growth, angiogenesis and metastasis. The C-terminus part of HARP composed of amino acids 111 to 136 is particularly involved in its biological activities and we previously established that a synthetic peptide composed of the same amino acids (P111-136) was capable of inhibiting the biological activities of HARP. Here we evaluate the ability of P111-136 to inhibit in vitro and in vivo the growth of a human tumour cell line PC-3 which possess an HARP autocrine loop.

METHODS:

A total lysate of PC-3 cells was incubated with biotinylated P111-136 and pulled down for the presence of the HARP receptors in Western blot. In vitro, the P111-136 effect on HARP autocrine loop in PC-3 cells was determined by colony formation in soft agar. In vivo, PC-3 cells were inoculated in the flank of athymic nude mice. Animals were treated with P111-136 (5 mg/kg/day) for 25 days. Tumour volume was evaluated during the treatment. After the animal sacrifice, the tumour apoptosis and associated angiogenesis were evaluated by immunohistochemistry. In vivo anti-angiogenic effect was confirmed using a mouse Matrigel™ plug assay.

RESULTS:

Using pull down experiments, we identified the HARP receptors RPTPβ/ζ, ALK and nucleolin as P111-136 binding proteins. In vitro, P111-136 inhibits dose-dependently PC-3 cell colony formation. Treatment with P111-136 inhibits significantly the PC-3 tumour growth in the xenograft model as well as tumour angiogenesis. The angiostatic effect of P111-136 on HARP was also confirmed using an in vivo Matrigel™ plug assay in mice

CONCLUSIONS:

Our results demonstrate that P111-136 strongly inhibits the mitogenic effect of HARP on in vitro and in vivo growth of PC-3 cells. This inhibition could be linked to a direct or indirect binding of this peptide to the HARP receptors (ALK, RPTPβ/ζ, nucleolin). In vivo, the P111-136 treatment significantly inhibits both the PC-3 tumour growth and the associated angiogenesis. Thus, P111-136 may be considered as an interesting pharmacological tool to interfere with tumour growth that has now to be evaluated in other cancer types.

• Authors: Yamina Hamma-Kourbali, Oya Bermek, Isabelle Bernard-Pierrot, Racha Karaky, Dominique Martel-Renoir, Sophie Frechault, José Courty, Jean Delbé
• Journal: BMC cancer (BMC Cancer) Vol. 11 Pg. 212 (May 30 2011) ISSN: 1471-2407 [Electronic] England
• PMID: 21624116 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carrier Proteins
• Cytokines
• Peptides
• pleiotrophin

Topics

• Adenocarcinoma (metabolism, pathology)
• Animals
• Apoptosis (drug effects)
• Carrier Proteins (chemistry, pharmacology)
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cytokines (chemistry, pharmacology)
• Female
• Humans
• Male
• Mice
• Mice, Nude
• Neovascularization, Pathologic (pathology)
• Peptides (chemical synthesis, pharmacology)
• Prostatic Neoplasms (metabolism, pathology)
• Protein Binding (drug effects)
• Xenograft Model Antitumor Assays