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// Emily Capone 1, * , Francesco Giansanti 2, * , Sara Ponziani 2, 3 , Alessia Lamolinara 4 , Manuela Iezzi 4 , Annamaria Cimini 2, 5, 6 , Francesco Angelucci 2 , Rossana La Sorda 3 , Vincenzo De Laurenzi 1 , Pier Giorgio Natali 3 , Rodolfo Ippoliti 2 , Stefano Iacobelli 1, 3 and Gianluca Sala 1, 3 1 Department of Medical, Oral and Biotechnological Sciences, University of Chieti-Pescara, Chieti, Italy 2 Department of Life, Health and Environmental Sciences, University of L'Aquila, Coppito (AQ) Italy 3 MediaPharma s.r.l., Via della Colonnetta, Chieti, Italy 4 Department of Medicine and Aging Science, Center of Excellence on Aging and Translational Medicine (CeSi-Met), G. D’Annunzio University, Chieti-Pescara, Italy 5 Sbarro Institute for Cancer Research and Molecular Medicine and Center for Biotechnology Temple University, Philadelphia, USA 6 National Institute for Nuclear Physics (INFN), Gran Sasso National Laboratory (LNGS), Assergi, Italy * These authors have contributed equally to this work Correspondence to: Gianluca Sala, email: g.sala@unich.it Stefano Iacobelli, email: iacobell@unich.it Keywords: HER-3, antibody-drug conjugate, melanoma, saporin, target therapy Received: June 22, 2017 Accepted: August 08, 2017 Published: September 08, 2017 ABSTRACT Melanoma is the most biologically aggressive skin cancer of well established constitutive and induced resistance to pharmacological treatment. Despite the recent progresses in immunotherapies, many advanced metastatic melanoma patients still face a significant mortality risk. The aggressive nature of this disease sustains an urgent need for more successful, effective drugs. HER-3 - one of the four member of the tyrosin kinase epidermal growth factor receptors (EGFRs) family- is frequently overexpressed in solid tumors, including melanoma. Moreover, up-regulation of HER-3 and its ligand NRGβ-1 are associated with poor prognosis, thus suggesting this receptor as a suitable target for cancer therapy. Several monoclonal antibodies targeting HER-3 are currently available, but preliminary results from clinical testing of these agents reveal a modest efficacy. Thus, a substantial improvement over this immunotherapeutic approach could be offered by an anti-HER-3 based Antibody-Drug Conjugate (ADC). In the present paper, we describe the generation of an ADC obtained by coupling the HER-3 targeting antibody EV20 linked to the plant toxin Saporin (Sap). In vitro , this ADC displays a powerful, specific and target-dependent cytotoxic activity which correlates with the degree of expression and internalization of HER-3 on tumor cells. Furthermore, in a murine melanoma model, EV20-Sap treatment leads to a significant reduction of the number of pulmonary metastasis.

Trop-2 is overexpressed in most human cancers, suggesting selective pressure for a key, conserved function. Here we show that Trop-2 stimulates cancer cell growth through the activation of a constitutively expressed, yet otherwise dormant, growth-control module. We discovered that crosslinking of membrane Trop-2 with specific Abs leads to a cytoplasmic Ca2+ raise through interaction with the Na+/K+-ATPase α1 subunit and mobilization of the intracellular stores. This triggers a feed-forward loop through Trop-2-dependent activation and membrane recruitment of PKCα;, which in turn phosphorylates the Trop-2 cytoplasmic tail at two target sites, activating the molecule to stimulate its downstream signaling targets Akt and ERK. Our findings indicate that the Trop-2-triggered cell growth operates through binding and extensive crosstalk with CD9, CD81, CD82 and CD151 through PKCα. Detailed analysis of CD9 and CD81 indicates that they bind to the HIKE region of the Trop-2 intracellular tail. Correspondingly, we found that the HIKE region of Trop-2 mediates its anchoring to the β-actin cytoskeleton through direct interaction with the ERM protein ezrin. Consistently, the Trop-2-dependent dynamic remodeling of the cell cytoskeleton is discovered to occur through activation of myosin II and binding of annexins A1/A11, α-actinin and gelsolin. Systematic drug screening, gene expression silencing and site-directed mutagenesis revealed that cytoskeleton disassembly, HIKE deletion and CD9 inhibition revert the growth of Trop-2-expressing cancer cells to that of their Trop-2-null counterparts. On the other hand, these inhibitors have no effects on basal cell growth. This indicates that Trop-2-centered protein interactions and activations are an essential step for the Trop-2-dependent cancer growth. Tight co-expression of the key components of the Trop-2 growth-stimulatory complex is found in a large breast cancer case series, thus indicating strong clinical relevance. Hence, Trop-2 triggers a universal, but otherwise dormant, layer of cancer growth, that overrides basal cell growth regulatory mechanisms and sensitizes tumors to targeted anticancer therapies. Citation Format: Marco Trerotola, Valeria Relli, Romina Tripaldi, Andrea Sacchetti, Kristina Havas, Pasquale Simeone, Emanuela Guerra, Annalaura Aloisi, Rossana La Sorda, Rossano Lattanzio, Daniele Vergara, Isabelle Fournier, Michel Salzet, Mauro Piantelli, Saverio Alberti. Trop-2 activates a dormant Na+/K+-ATPase/PKCα/CD9/ezrin signaling axis to override the basal growth program of cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 367. doi:10.1158/1538-7445.AM2017-367

Accumulating evidence indicates that serum and tissue levels of lectin, galactoside-binding soluble 3 binding protein (LGALS3BP), a secreted glycoprotein, are elevated in human cancers. Recently, we have identified LGALS3BP as a factor capable of stimulating angiogenesis of microvascular endothelial cells in vitro as well as in vivo. However, the potential therapeutic implications of LGALS3BP function blockade have not been explored yet. Here, we tested the ability of an anti-LGALS3BP mouse monoclonal antibody, SP-2, to antagonize LGALS3BP-induced angiogenesis and tumor growth. The antibody was found to inhibit endothelial cell tubulogenesis induced by either conditioned medium of breast cancer and melanoma cells or human recombinant LGALS3BP. In addition, SP-2 inhibited phosphorylation of FAK and its recruitment to membrane sites as well as AKT and ERK phosphorylation promoted by LGALS3BP. When used in vivo, the antibody restrained LGALS3BP-stimulated angiogenesis and growth of tumor xenografts. Furthermore, the combination of SP-2 and low-dose bevacizumab was more effective than either agent alone. Taken together, these results lead to consideration of SP-2 as a promising candidate for LGALS3BP-targeted therapy. Mol Cancer Ther; 13(4); 916–25. ©2014 AACR.

Purpose: Inhibition of AKT is a key target area for personalized cancer medicine. However, predictive markers of response to AKT inhibitors are lacking. Correspondingly, the AKT-dependent chain of command for tumor growth, which will mediate AKT-dependent therapeutic responses, remains unclear. Experimental Design: Proteomic profiling was utilized to identify nodal hubs of the Trop-2 cancer growth–driving network. Kinase-specific inhibitors were used to dissect Trop-2–dependent from Trop-2–independent pathways. In vitro assays, in vivo preclinical models, and case series of primary human breast cancers were utilized to define the mechanisms of Trop-2–driven growth and the mode of action of Trop-2–predicted AKT inhibitors. Results: Trop-2 and AKT expression was shown to be tightly coordinated in human breast cancers, with virtual overlap with AKT activation profiles at T308 and S473, consistent with functional interaction in vivo. AKT allosteric inhibitors were shown to only block the growth of Trop-2–expressing tumor cells, both in vitro and in preclinical models, being ineffective on Trop-2–null cells. Consistently, AKT-targeted siRNA only impacted on Trop-2–expressing cells. Lentiviral downregulation of endogenous Trop-2 abolished tumor response to AKT blockade, indicating Trop-2 as a mandatory activator of AKT. Conclusions: Our findings indicate that the expression of Trop-2 is a stringent predictor of tumor response to AKT inhibitors. They also support the identification of target-activatory pathways, as efficient predictors of response in precision cancer therapy. Clin Cancer Res; 22(16); 4197–205. ©2016 AACR.

Elevated serum or tissue levels of lectin galactoside-binding soluble 3 binding protein (LGALS3BP) have been associated with short survival and development of metastasis in a variety of human cancers. However, the role of LGALS3BP, particularly in the context of tumor-host relationships, is still missing. Here, we show that LGALS3BP knockdown in MDA-MB-231 human breast cancer cells leads to a decreased adhesion to fibronectin, a reduced transendothelial migration and, more importantly, a reduced expression of vascular endothelial growth factor (VEGF). Production of VEGF, that was restored by exposure of silenced cells to recombinant LGALS3BP, required an intact PI3k/Akt signaling. Furthermore, we show that LGALS3BP was able to directly stimulate HUVEC tubulogenesis in a VEGF-independent, galectin-3-dependent manner. Immunohistochemical analysis of human breast cancer tissues revealed a correlation among LGALS3BP expression, VEGF expression, and blood vessel density. We propose that in addition to its prometastatic role, LGALS3BP secreted by breast cancer cells functions critically as a pro-angiogenic factor through a dual mechanism, i.e by induction of tumor VEGF and stimulation of endothelial cell tubulogenesis.

Congenital tufting enteropathy (CTE) is a life-threatening hereditary disease that is characterized by enteric mucosa tufting degeneration and early onset, severe diarrhea. Loss-of-function mutations of the human EPCAM gene (TROP1, TACSTD1) have been indicated as the cause of CTE. However, loss of mTrop1/Epcam in mice appeared to lead to death in utero, due to placental malformation. This and indications of residual Trop-1/EpCAM expression in cases of CTE cast doubt on the role of mTrop1/Epcam in this disease. The aim of this study was to determine the role of TROP1/EPCAM in CTE and to generate an animal model of this disease for molecular investigation and therapy development. Using a rigorous gene-trapping approach, we obtained mTrop1/Epcam -null (knockout) mice. These were born alive, but failed to thrive, and died soon after birth because of hemorrhagic diarrhea. The intestine from the mTrop1/Epcam knockout mice showed intestinal tufts, villous atrophy and colon crypt hyperplasia, as in human CTE. No structural defects were detected in other organs. These results are consistent with TROP1/EPCAM loss being the cause of CTE, thus providing a viable animal model for this disease, and a benchmark for its pathogenetic course. In the affected enteric mucosa, E-cadherin and β-catenin were shown to be dysregulated, leading to disorganized transition from crypts to villi, with progressive loss of membrane localization and increasing intracellular accumulation, thus unraveling an essential role for Trop-1/EpCAM in the maintenance of intestinal architecture and functionality. Supporting information is available for this article.

Flavonoids comprise a class of low molecular weight compounds displaying a variety of biological activities including inhibition of tumor growth and metastasis. To gain insight into the mechanisms underlying metastasis inhibition, we have employed the B16-BL6 murine melanoma metastasis model. B57BL/6N mice were injected i.v. with tumor cells and Apigenin, Quercetin, or Tamoxifen, each at 50 mg/kg given i.p., and lung tumor cell colonies counted 14-6 days thereafter. Three different injection schedules were used for each drug: (a) daily injection, starting 24 h before injection of the tumor cells; (b) single dose, 24 h preceding tumor challenge; (c) daily injection, starting 24 h after the injection of the tumor cells. All three compounds significantly reduced tumor lung deposits (Apigenin = Quercetin > Tamoxifen). However, when treatment was delayed by 24 h after tumor cells (schedule c), multiple daily doses of Apigenin or Quercetin were less effective that a single dose of the same compound given 24 h before tumor challenge (schedule b). Apigenin and Quercetin, but not Tamoxifen, were found to inhibit VCAM-1 expression in a dose-dependent manner in HUVEC and in murine pulmonary endothelial cells. In ex vivo experiments, the number of tumor cells adhering to lung vessels was significantly diminished in animals treated with a single dose of Apigenin and Quercetin. These findings indicate that the inhibition of tumor cell metastasis by Apigenin or Quercetin may significantly depend on the ability of these compounds to alter the host's microenvironment, further substantiating the role of the intravascular processes in the metastatic cascade.

Background: Accumulating evidence indicates that serum and tissue levels of the lectin galactoside-binding soluble 3 binding protein (LGALS3BP), a secreted glycoprotein, are elevated in human cancer. Recently, we have identified LGALS3BP as a factor capable of stimulating angiogenesis of microvascular endothelial cells in culture as well as in vivo. However, the potential therapeutic implications of LGALS3BP function blockade, has not been explored yet. Methods: Here we tested the ability of an anti-LGALS3BP monoclonal antibody, named SP-2, to antagonize LGALS3BP-induced angiogenesis and tumor growth. Results: SP-2 dose-dependently inhibited HUVEC tubulogenesis induced by either conditioned medium of breast cancer and melanoma cells or purified recombinant LGALS3BP. This was accompanied by inhibition of FAK, Akt and ERKs phosphorylation as well as FAK recruitment to membrane sites and actin remodeling. In vivo, SP-2 inhibited LGALS3BP-stimulated angiogenesis and restrained growth of different xenograft models of human cancer. Finally, the combination of SP-2 with low-dose Bevacizumab was more effective than either agent alone in suppressing angiogenesis and tumor growth. Conclusions: Targeting LGALS3BP with SP-2 could represent a promising therapeutic approach for LGALS3BP expressing tumors. Citation Format: Enza Piccolo, Sara Trani, Nicola Tinari, Cosmo Rossi, Rossana La Sorda, Rossano Lattanzio, Maurizia D'Egidio, Annalisa Di Risio, Antonino Grassadonia, Francesca Spinella, Anna Bagnato, Mauro Piantelli, Clara Natoli, Stefano Iacobelli. Inhibition of tumor growth and angiogenesis by SP-2, an anti-LGALS3BP antibody. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2684. doi:10.1158/1538-7445.AM2014-2684

Nectins are Ca(2+)-independent immunoglobulin-like cell adhesion molecules that compose a family of four members that regulate several cellular activities such as movement, proliferation, survival, differentiation, polarization, and the entry of viruses. Nectin-4 has recently emerged as a metastatis-associated protein in several cancers. Here, we have evaluated the association between the expression of Nectin-4 and the clinical outcome of patients with node-negative, T1/T2 breast cancers.The study group consisted of 197 patients presenting with primary unilateral breast carcinoma (T1/T2), with no evidence of nodal involvement and distant metastases. Nectin-4 protein expression was assessed by immunohistochemistry on tissue microarrays, and the results correlated with the clinical data using Kaplan-Meier curves and multivariate Cox regression analysis. Thirty-four out of 197 tumors (17.3%) exhibited Nectin-4 expression on cell membrane (m-Nectin-4) and 122 out of the 163m-Nectin-4 negative tumors (74.8%) showed high cytoplasmic expression of Nectin-4 (c-Nectin-4(High)). At Kaplan-Meier analysis, m-Nectin-4 positivity was significantly associated with a lower disease-free survival (DFS) and distant relapse-free survival (DRFS) rate in patients with a luminal-A phenotype (P=0.030 and P=0.002, respectively). Multivariate analysis showed that in luminal-A tumors m-Nectin-4 positivity is an independent prognostic factor for DFS (P=0.018) and DRFS (P=0.004), but not for local relapse-free survival (LRFS). On the other hand, c-Nectin-4(High) was significantly associated with higher rates of DFS and LRFS, but not DRFS, in the whole population (P=0.008 and P=0.004, respectively) and in patients with luminal-A tumors (P=0.022 and P=0.018, respectively). In patients with luminal-A tumors, multivariate analysis showed that the prognostic value of c-Nectin-4(Low/Negative) is limited to DFS (P=0.012) and LRFS (P=0.022). We suggest that Nectin-4 represents a prognostic factor and a therapeutic target in luminal-A early stage breast cancer.

Trop-2 is a calcium signal transducer that drives tumor growth. Anti-Trop-2 antibodies with selective reactivity versus Trop-2 maturation stages allowed to identify two different pools of Trop-2, one localized in the cell membrane and one in the cytoplasm. Of note, membrane-localized/functional Trop-2 was found to be differentially associated with determinants of tumor aggressiveness and distinct breast cancer subgroups. These findings candidated Trop-2 states to having an impact on cancer progression. We tested this model in breast cancer. A large, consecutive human breast cancer case series (702 cases; 8 years median follow-up) was analyzed by immunohistochemistry with anti-Trop-2 antibodies with selective reactivity for cytoplasmic-retained versus functional, membrane-associated Trop-2. We show that membrane localization of Trop-2 is an unfavorable prognostic factor for overall survival (1+ versus 0 for all deaths: hazard ratio, 1.63; P = 0.04), whereas intracellular Trop-2 has a favorable impact on prognosis, with an adjusted hazard ratio for all deaths of 0.48 (high versus low; P = 0.003). A corresponding impact of intracellular Trop-2 was found on disease relapse (high versus low: hazard ratio, 0.51; P = 0.004). Altogether, we demonstrate that the Trop-2 activation states are critical determinants of tumor progression and are powerful indicators of breast cancer patients survival.

BackgroundThe pathogenic road map leading to Alzheimer's disease (AD) is still not completely understood; however, a large body of studies in the last few years supports the idea that beside the classic hallmarks of the disease, namely the accumulation of amyloid-β (Aβ) and neurofibrillary tangles, other factors significantly contribute to the initiation and the progression of the disease. Among them, mitochondria failure, an unbalanced neuronal redox state, and the dyshomeostasis of endogenous metals like copper, iron, and zinc have all been reported to play an important role in exacerbating AD pathology. Given these factors, the endogenous peptide carnosine may be potentially beneficial in the treatment of AD because of its free-radical scavenger and metal chelating properties.MethodologyIn this study, we explored the effect of L-carnosine supplementation in the 3xTg-AD mouse, an animal model of AD that shows both Aβ- and tau-dependent pathology.Principal findingsWe found that carnosine supplementation in 3xTg-AD mice promotes a strong reduction in the hippocampal intraneuronal accumulation of Aβ and completely rescues AD and aging-related mitochondrial dysfunctions. No effects were found on tau pathology and we only observed a trend toward the amelioration of cognitive deficits.Conclusions and significanceOur data indicate that carnosine can be part of a combined therapeutic approach for the treatment of AD.

Background A previous report has shown that LGALS3BP (also known as 90K or Mac-2 BP) has antitumor activity in colorectal cancer (CRC) via suppression of Wnt signalling with a novel mechanism of ISGylation-dependent ubiquitination of β-catenin. The role of LGALS3BP in CRC prognosis was investigated. Methods The role of LGALS3BP on CRC progression and clinical prognosis was analyzed by combining cell cultures, in vitro assays, and immunohistochemistry. Results Silencing of LGALS3BP in HCT-116 human colon cancer cells resulted in enhanced β-catenin expression that was reversed by addition of human recombinant LGALS3BP. Moreover, intra-tumor delivery of LGALS3BP reduced tumor growth of xenografts originating from LGALS3BP-silenced HCT-116 cells. Finally, in a series of 196 CRC patients, LGALS3BP expression in tumor tissue associated with clinical outcome. Patients with high LGALS3BP expression had lower risk of relapse and a longer overall survival time than those with low LGALS3BP expression. Multivariate analyses confirmed LGALS3BP expression status as the only independent prognostic factor of survival. Conclusions These results provide evidence that low expression of LGALS3BP participates in malignant progression of CRC and implicates poor prognosis, highlighting its augmentation as a potential therapeutic approach.