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

BackgroundHeparin 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.MethodsA 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.ResultsUsing 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 miceConclusionsOur 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.

Implications of pleiotrophin in human PC3 prostate cancer cell growth in vivo

“…Overexpression of PTN that lacks its carboxy‐terminal domain acts as a dominant negative form of PTN and inhibits prostate cancer cell growth in vitro . Similarly, a peptide that corresponds to the carboxy‐terminal domain of PTN and binds to RPTPβ/ζ, inhibits prostate cancer cell response to PTN in vitro and PC3 tumor growth in vivo , although in the latter case it has not been shown whether its effect was solely due to endogenous PTN inhibition through RPTPβ/ζ and not interference with other implicated pathways. We have previously shown that a similar peptide inhibits the stimulatory effect of PTN on endothelial cell migration through inhibition of PTN interaction with α ν β 3 integrin .…”

Pleiotrophin Exerts Its Migration and Invasion Effect through the Neuropilin-1 Pathway

“…PTN expression is limited in adults, except at such sites as mammary gland and uterus, which are associated with reproductive angiogenesis [3] , [4] . Studies of the pathological involvement of PTN indicate that this molecule may be considered a proto-oncogene [3] , [5] overexpressed in various malignant human tumors and tumor cell lines, such as breast, prostate, colon, and skin, as well as being involved in tumor angiogenesis and metastasis [2] , [6] , [7] , [8] .…”

Angiogenesis biomarkers and their targeting ligands as potential targets for tumor angiogenesis

“…NCL has many roles including ribosome assembly (Allain, Gilbert, Bouvet, & Feigon, ; Bouvet, Diaz, Kindbeiter, Madjar, & Amalric, ), regulation of cell cycle and transcription (Ugrinova et al, ; Yang et al, ; Ying et al, ), regulation of apoptosis (Otake et al, ), viral attachment and entry to the host cell (Nisole, Krust, & Hovanessian, ; Tayyari et al, ), and many other physiological and pathological conditions (Caudle, Kitsou, Li, Bradner, & Zhang, ; Dranovsky et al, ). Many reports indicated that NCL is expressed on the surface of cells including angiogenic endothelial cells (Christian et al, ; Huang et al, ), and many types of cancer cells (Destouches et al, ; Hamma‐Kourbali et al, ; Joo et al, ; Krust, El Khoury, Soundaramourty, Nondier, & Hovanessian, ; Mi et al, ; Qiu et al, ). Table shows some ligands which target cell surface nucleolin and promising results in dual targeting of both tumor angiogenesis and tumor growth have been obtained (Bates, Laber, Miller, Thomas, & Trent, ; El Khoury et al, ).…”