Pleiotrophin (PTN) is a 136-amino acid secreted heparinbinding protein that is considered as a rate-limiting growth and an angiogenic factor in the onset, invasion, and metastatic process of many tumors. Its mitogenic and tumorigenic activities are mediated by the COOH-terminal residues 111 to 136 of PTN, allowing it to bind to cell surface tyrosine kinase-linked receptors. We investigated a new strategy consisting in evaluating the antitumor effect of a truncated PTN, lacking the COOH-terminal 111 to 136 portion of the molecule (PTN#111-136), which may act as a dominant-negative effector for its mitogenic, angiogenic, and tumorigenic activities by heterodimerizing with the wild-type protein. In vitro studies showed that PTN#111-136 selectively inhibited a PTN-dependent MDA-MB-231 breast tumor and endothelial cell proliferation and that, in MDA-MB-231 cells expressing PTN#111-136, the vascular endothelial growth factor-A and hypoxia-inducible factor-1A mRNA levels were significantly decreased by 59% and 71%, respectively, compared with levels in wild-type cells. In vivo, intramuscular electrotransfer of a plasmid encoding a secretable form of PTN#111-136 was shown to inhibit MDA-MB-231 tumor growth by 81%. This antitumor effect was associated with the detection of the PTN#111-136 molecule in the muscle and tumor extracts, the suppression of neovascularization within the tumors, and a decline in the Ki-67 proliferative index. Because PTN is rarely found in normal tissue, our data show that targeted PTN may represent an attractive and new therapeutic approach to the fight against cancer.

Brain tumors can present with various psychiatric symptoms, with or without neurological symptoms, an aspect that complicates the clinical picture. However, no systematic description of symptoms that should prompt a neurological investigation has been provided. This review aims to summarize available case reports describing patients with brain tumors showing psychiatric symptoms before brain tumor diagnosis, in order to provide a comprehensive description of these symptoms as well as their potential relationship with delay in the diagnosis. A systematic literature review on case reports of brain tumors and psychiatric symptoms from 1970 to 2020 was conducted on PubMed, Ovid, Psych Info, and MEDLINE. Exclusion criteria comprised tumors not included in the World Health Organization (WHO) Classification 4th edition and cases in which psychiatric symptoms were absent or followed the diagnosis. A total of 165 case reports were analyzed. In a subset of patients with brain tumors, psychiatric symptoms can be the only manifestation or precede focal neurological signs by months or even years. The appearance of focal or generalized neurological symptoms after, rather than along with, psychiatric symptoms was associated with a significant delay in the diagnosis in adults. A timely assessment of psychiatric symptoms might help to improve early diagnosis of brain tumors.

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Glioblastoma is the most common primary brain tumor in human adults. Since existing treatments are not effective enough, novel therapeutic targets must be sought. The heparin-binding growth factor, heparin affin regulatory peptide (HARP), also known as pleiotrophin (PTN), could potentially represent such a target. We have previously shown that a mutant protein, HARPD111-136, which lacks HARP's C-terminal 26 amino acids, acts as a dominant negative HARP effector by heterodimerizing with the wild-type growth factor. The aim of our study was to evaluate the potential inhibitory activity of HARPD111-136 on the U87 MG human glioblastoma cell line. By overexpressing the truncated form of HARP in stably established clones of U87 MG cells, we observed an inhibition of proliferation under both anchorage-dependent and anchorage-independent conditions. We confirmed these results in an in vivo subcutaneous tumor xenograft model. In addition, we found that HARPD111-136 inhibited cell proliferation in a paracrine manner. Analysis of key cellular pathways revealed a decrease of cell adhesion in U87 MG cells that overexpressed the mutant protein, which could explain this inhibitory effect. A replication-defective adenovirus model that encoded HARPD111-136 supported a putative antiproliferative role for the truncated protein in vitro and in vivo. Interestingly, HARPD111-136 was also able to abolish angiogenic activity in HUVEC proliferation and in a Matrigel plug assay. These results demonstrate that considering its antiproliferative and angiostatic effects, HARPD111-136 could be of great interest when used in conjunction with standard treatments.Glioblastoma is the most common primary brain tumor in adult humans, with a median survival time of 12 months from the time of diagnosis, despite using standard therapeutic approaches (surgery, radiation and chemotherapy). A proper understanding of the principal pathways implicated in glioblastoma progression is needed to identify potential therapeutic targets. The heparin-binding growth factor, heparin affin regulatory peptide (HARP), also known as pleiotrophin (PTN) and heparin-binding growth-associated molecule (HB-GAM), could represent 1 such potential target.HARP is a 136-amino acid secreted polypeptide that forms with the protein midkine (MK), a 2-member family of heparin-binding growth factors. HARP is a developmentally regulated cytokine that is highly expressed in the embryonic nervous system, but its expression drops markedly after the perinatal phase and during adulthood. However, HARP expression may be deregulated, and HARP has been shown to be overexpressed in various tumor cell lines and primary human tumors, 1-3 including glioblastomas. In vitro, HARP displays a variety of biological activities including mitogenesis, angiogenesis, neurite outgrowth and cell migration. 4 Transforming activity has also been demonstrated for HARP when it is overexpressed in nontumor cell lines, such as NIH 3T3. 5Two transmembrane proteins with intracellular catalytic domains have been descri...

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.