Exploiting frequent and specific expression of PRL3 in pediatric solid tumors for first-in-child use of PRL3-zumab humanized antibody.

Phosphatase of regenerating liver 3 (PRL3) is a specific tumor antigen overexpressed in a broad range of adult cancer types. However, its physiological expression in pediatric embryonal and mesenchymal tumors and its association with clinical outcomes in children is unknown. We sought to profile the expression of PRL3 in pediatric tumors in relation to survival outcomes, expression of angiogenesis markers, and G-protein-coupled receptor (GPCR)-mitogen-activated protein kinase (MAPK) signaling targets. PRL3-zumab, a first-in-class humanized antibody, was administered in a dose escalation schedule in a first-in-child clinical trial to study toxicity, pharmacokinetics, and clinical outcomes. Among 64 pediatric tumors, PRL3 was most frequently expressed in neuroblastoma (100%), rhabdomyosarcoma and non-rhabdomyosarcoma soft tissue sarcomas (71%), and renal sarcomas (60%) but absent in paired normal tissues. PRL3 was expressed in 75% of relapsed tumors and associated with shorter median event-free survival. Microarray profiling of PRL3-positive tumors showed elevation of angiogenin, TIMP1 and TIMP2, and GPCR-MAPK signaling proteins that commonly interacted with PRL3. The first use of PRL3-zumab in a pediatric patient saw no adverse events. A 28.6% reduction in maximum target lesion diameter was achieved when PRL3-zumab was administered concurrently with hypofractionated radiation. These findings support wider exploration of PRL3 expression in embryonal and mesenchymal tumors and further clinical application of PRL3-zumab in pediatric patients.

PRL3 as a therapeutic target for novel cancer immunotherapy in multiple cancer types.

Phosphatase of Regenerating Liver-3 (PRL3) was discovered in 1998 and was subsequently found to be correlated with cancer progression and metastasis in 2001. Extensive research in the past two decades has produced significant findings on PRL3-mediated cancer signaling and functions, as well as its clinical relevance in diverse types of cancer. PRL3 has been established to play a role in many cancer-related functions, including but not limited to metastasis, proliferation, and angiogenesis. Importantly, the tumor-specific expression of PRL3 protein in multiple cancer types has made it an attractive therapeutic target. Much effort has been made in developing PRL3-targeted therapy with small chemical inhibitors against intracellular PRL3, and notably, the development of PRL3-zumab as a novel cancer immunotherapy against PRL3. In this review, we summarize the current understanding of the role of PRL3 in cancer-related cellular functions, its prognostic value, as well as perspectives on PRL3 as a target for unconventional immunotherapy in the clinic with PRL3-zumab.

ELTD1 is present in extracellular vesicles derived from endothelial cells as a cleaved extracellular domain which induces in vivo angiogenesis.

ELTD1/ADGRL4 is an adhesion GPCR with an important role in angiogenesis. We recently identified a role for ELTD1 in wound repair and inflammation. Activation of ELTD1 in endothelial cells results in a type II EMT to myofibroblast-like cells that have enhanced angiogenic ability. Furthermore, expression of Eltd1 in murine breast cancer cells increases tumour growth by increasing blood vessel size and perfusion and by creating an immunosuppressive microenvironment. As extracellular vesicles (EVs) are known to be involved in vascular development, growth and maturation we investigated the composition and functional effects of the EVs isolated from ELTD1 expressing cells to elucidate their role in these processes. A highly glycosylated form of the extracellular domain (ECD) of ELTD1 is readily incorporated into EVs. Using mass spectrometry-based proteomics we identified proteins that are enriched in ELTD1-EVs and are involved in haemostasis and immune responses. ELTD1 enriched EVs were pro-angiogenic in vivo and in vitro and the presence of the ECD alone induced endothelial sprouting. In endothelial cells experiencing laminar flow, ELTD1 levels were reduced in the EVs when they are quiescent, showing a relationship between ELTD1 and the activation state of the endothelium. Using FACS, we detected a significant increase in vesicular ELTD1 in the plasma of patients with preeclampsia, a condition characterized by endothelial dysfunction. These data confirm a role for ELTD1 in wound repair and inflammation and reveal its potential as a biomarker of vessel dysfunction.

PRL3 induces polypoid giant cancer cells eliminated by PRL3-zumab to reduce tumor relapse.

PRL3, a unique oncotarget, is specifically overexpressed in 80.6% of cancers. In 2003, we reported that PRL3 promotes cell migration, invasion, and metastasis. Herein, firstly, we show that PRL3 induces Polyploid Giant Cancer Cells (PGCCs) formation. PGCCs constitute stem cell-like pools to facilitate cell survival, chemo-resistance, and tumor relapse. The correlations between PRL3 overexpression and PGCCs attributes raised possibilities that PRL3 could be involved in PGCCs formation. Secondly, we show that PRL3+ PGCCs co-express the embryonic stem cell markers SOX2 and OCT4 and arise mainly due to incomplete cytokinesis despite extensive DNA damage. Thirdly, we reveal that PRL3+ PGCCs tolerate prolonged chemotherapy-induced genotoxic stress via suppression of the pro-apoptotic ATM DNA damage-signaling pathway. Fourthly, we demonstrated PRL3-zumab, a First-in-Class humanized antibody drug against PRL3 oncotarget, could reduce tumor relapse in 'tumor removal' animal model. Finally, we confirmed that PGCCs were enriched in relapse tumors versus primary tumors. PRL3-zumab has been approved for Phase 2 clinical trials in Singapore, US, and China to block all solid tumors. This study further showed PRL3-zumab could potentially serve an 'Adjuvant Immunotherapy' after tumor removal surgery to eliminate PRL3+ PGCC stem-like cells, preventing metastasis and relapse.

Immunostimulating and Gram-negative-specific antibacterial cyclotides from the butterfly pea (Clitoria ternatea).

UNLABELLED: Cyclotides are plant-derived, cyclic miniproteins with three interlocking disulfide bonds that have attracted great interests because of their excellent stability and potential as peptide therapeutics. In this study, we characterize the cyclotides of the medicinal plant Clitoria ternatea (butterfly pea) and investigate their biological activities. Using a combined proteomic and transcriptomic method, we identified 41 novel cyclotide sequences, which we named cliotides, making C. ternatea one of the richest cyclotide-producing plants to date. Selected members of the cationic cliotides display potent antibacterial activity specifically against Gram-negative bacteria with minimal inhibitory concentrations as low as 0.5 µm. Remarkably, they also possess prominent immunostimulating activity. At a concentration of 1 µm, cationic cliotides are capable of augmenting the secretion of various cytokines and chemokines in human monocytes at both resting and lipopolysaccharide-stimulated states. Chemokines such as macrophage inflammatory proteins 1α and 1ß, interferon γ-induced protein 10, interleukin 8 and tumor necrosis factor α were among the most upregulated with up to 129-fold increase in secretion level. These findings suggest cyclotides can serve as potential candidates for novel immunomodulating therapeutics. DATABASE: The protein sequences reported in this paper (cT13-cT21) are available in the UniProt Knowledgebase under the accession numbers C0HJS0, C0HJS1, C0HJS2, C0HJS3, C0HJS4, C0HJS5, C0HJS6, C0HJS7 and C0HJS8, respectively. The transcriptome data in this paper are available at the Sequence Read Archive database (NCBI) under accession number SRR1613316. The protein precursors reported in this paper (ctc13, ctc15, ctc17-ctc19, ctc21-ctc53) are available at GenBank under the accession numbers KT732712, KT732713, KT732714, KT732715, KT732716, KT732717, KT732718, KT732719, KT732720, KT732721, KT732722, KT732723, KT732724, KT732725, KT732726, KT732727, KT732728, KT732729, KT732730, KT732731, KT732732, KT732733, KT732734, KT732735, KT732736, KT732737, KT732738, KT732739, KT732740, KT732741, KT732742, KT732743, KT732744, KT732745, KT732746, KT732747, KT732748 and KT732749, respectively.