Contents lists available at ScienceDirect Phytomedicine journal homepage: www.elsevier.com/locate/phymed Indicaxanthin from Opuntia Ficus Indica (L. Mill) impairs melanoma cell proliferation, invasiveness, and tumor progression Mario Allegra a , Paola De Cicco b , Giuseppe Ercolano b , Alessandro Attanzio a , Rosalia Busà a , Giuseppe Cirino b , Luisa Tesoriere a , Maria A. Livrea a , Angela Ianaro a, ⁎ a Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche, Università di Palermo, Via Archirafi 28, 90123 Palermo, Italy b Dipartimento di Farmacia, Scuola di Medicina, Università di Napoli Federico II, Via Montesano 49, 80131 Napoli, Italy ARTICLE INFO Keywords: Opuntia Ficus Indica (L.Mill) Indicaxanthin Melanoma Apoptosis Inflammation Phytochemical List of Abbrevations: AxV-FITC, annexin V- fluorescein isothiocyanate Bcl-2, B cell lymphoma gene-2 (Bcl-2) c-FLIP, FLICE-inhibitory protein CXCL1, chemokine (C-X-C motif) ligand 1 MTT, 3-[4,5-dimethyltiazol-2-yl]-2,5-diphenyl tetrazolium bromide NHEM, normal human epidermal melanocytes NF-κB, nuclear factor kappa B PhC, phytochemicals PI, propidium iodide PI ABSTRACT Background: A strong, reciprocal crosstalk between inflammation and melanoma has rigorously been demon- strated in recent years, showing how crucial is a pro-inflammatory microenvironment to drive therapy resistance and metastasis. Purpose: We investigated on the effects of Indicaxanthin, a novel, anti-inflammatory and bioa- vailable phytochemical from Opuntia Ficus Indica fruits, against human melanoma both in vitro and in vivo. Study Design and Methods: The effects of indicaxanthin were evaluated against the proliferation of A375 human mel- anoma cell line and in a mice model of cutaneous melanoma. Cell proliferation was assessed by MTT assay, apoptosis by Annexin V-Fluorescein Isothiocyanate/Propidium Iodide staining, protein expression by western blotting, melanoma lesions were subcutaneously injected in mice with B16/F10 cells, chemokine release was quantified by ELISA. Results: Data herein presented demonstrate that indicaxanthin effectively inhibits the proliferation of the highly metastatic and invasive A375 cells as shown by growth inhibition, apoptosis induction and cell invasiveness reduction. More interestingly, in vitro data were paralleled by those in vivo showing that indicaxanthin significantly reduced tumor development when orally administered to mice. The results of our study also clarify the molecular mechanisms underlying the antiproliferative effect of indicaxanthin, in- dividuating the inhibition of NF-κB pathway as predominant. Conclusion: In conclusion, we demonstrated that indicaxanthin represents a novel phytochemical able to significantly inhibit human melanoma cell proliferation in vitro and to impair tumor progression in vivo. When considering the resistance of melanoma to the current therapeutical approach and the very limited number of phytochemicals able to partially counteract it, our findings may be of interest to explore indicaxanthin potential in further and more complex melanoma studies in combo therapy, i.e. where different check points of melanoma development are targeted. Introduction Cancer is a growing health problem around the world and according to estimates from the International Agency for Research on Cancer (IARC), 14.1 million new cancer cases and 8.2 million cancer deaths worldwide have been reported in 2012 (Ferlay et al., 2015). By 2030, the global burden is expected to grow to 21.7 million new cancer cases and 13 million cancer deaths simply due to the growth and aging of the population. It has been estimated that more than two-thirds of human cancers could be prevented through modification of the lifestyle, with special attention to diet. The link between cancer risk and nutritional factors has clearly emerged in the past few years (Biesbroek et al., 2017; Bradbury et al., 2014). Specifically, both epidemiologic and basic science studies showed promising results on the effects of phytochem- icals (PhC) in the chemoprevention of melanoma (Caini et al., 2017; Strickland et al., 2015; Tong and Young, 2014). Along these lines, the investigation of new molecules able to counteract the onset and/or the development of this very aggressive cancer is rapidly growing (Strickland et al., 2015). Indicaxanthin ((2S)-2,3-dihydro-4-[2-[(2S)-2a-carboxypyrrolidin-1- yl]ethenyl]pyridine-2a,6-dicarboxylic acid), a betalain pigment from cactus pear fruit, has been the object of sound experimental work over the latest years. As many phytochemicals, indicaxanthin is a redox-ac- tive compound and has been shown to act as antioxidant in a number of in vitro studies (Allegra et al., 2005; Turco Liveri et al., 2009). Inter- estingly, thanks to its charged portions, ionizable groups and lipophilic moieties, it is amphiphilic at physiological pH (Turco Liveri et al., https://doi.org/10.1016/j.phymed.2018.09.171 Received 7 May 2018; Received in revised form 13 July 2018; Accepted 17 September 2018 ⁎ Corresponding author. E-mail address: ianaro@unina.it (A. Ianaro). Phytomedicine 50 (2018) 19–24 0944-7113/ © 2018 Elsevier GmbH. All rights reserved. T