Polyphenol tri-vanillic ester 13c inhibits P-JAK2V617F and Bcr–Abl oncokinase expression in correlation with STAT3/STAT5 inactivation and apoptosis induction in human leukemia cells Anne Trécul a , Franck Morceau a , Anthoula Gaigneaux a , Marion Orsini a , Sébastien Chateauvieux a , Cindy Grandjenette a , Mario Dicato a , Marc Diederich b,⇑ a Laboratoire de Biologie Moléculaire et Cellulaire du Cancer, Hôpital Kirchberg, 9, Rue Edward Steichen, 2540 Luxembourg, Luxembourg b Department of Pharmacy, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea article info Article history: Received 14 April 2013 Received in revised form 17 June 2013 Accepted 20 June 2013 Available online xxxx Keywords: Kinase JAK2 Bcr–Abl 13c Polyphenol STAT abstract Constitutive activity of kinases has been reported in many types of cancers, so that inhibition of ‘‘onco-kinases’’ became a validated anti-cancer strategy. We found that the polyphenol 13c, a tri-vanillate derivative, inhibited kinase phosphorylation in leukemia cells. P-JAK2, P-Src and P-PI3Kp85 inhibition occurred independently of phosphatase involvement in JAK2V617F expressing HEL cells while 13c inhibited Bcr–Abl expression without inhibition of phosphorylation in chronic myelogenous leukemia cell lines (K562, MEG-01). In correlation with kinase inhibition, 13c abolished constitutive P-STAT3/P-STAT5 expression, down-regulated Mcl-1 and c-Myc gene expression and induced apoptosis. Altogether, polyphenol 13c displays potential antitumor activities by affecting onco-kinases and STAT activities. Ó 2013 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Polyphenols are widely present in the vegetal kingdom as the products of the secondary metabolism of plants. Many studies have shown their potentialities as chemopreventive and antican- cer agents as well as for the treatment of cardiovascular, inflam- matory and neurodegenerative diseases [1]. Based on anticancer activities of vanillin, Lamoral-Theys et al. reported the cytostatic effect of a series of vanillate derivatives on several cancer cell lines in comparison to curcumin, a well known divanillate-based polyphenol for its anti-inflammatory and chemopreventive prop- erties [2]. Among 33 di- and trivanillate based polyphenol com- pounds studied, the authors reported that the tri-chloro derivative of trivanillic ester 13c, displayed one of the most po- tent in vitro antitumor activity. Besides cytostatic properties, 13c showed potent inhibitory activity of protein kinases in an in vitro kinase assay [3]. Many cancers express constitutively active kinases including Src (sarcoma viral oncogene homolog), JAK (Janus Kinase), Bcr– Abl (breakpoint cluster region-Abelson) and EGFR (epidermal growth factor receptor) [4,5]. Indeed, permanent activation of onco-kinases leads to upregulation of genes involved in cell cycle and survival including cyclins, c-Myc, Bcl-xL and Mcl-1 among oth- ers [5,6] through the constitutive activation of transcription factors including Signal Transducer and Activator of Transcription (STAT). Inhibition of constitutive activities and permanent phosphoryla- tion status of tyrosine kinases is a promising therapeutic pathway as revealed by Imatinib/Gleevec for example. Moreover, inactiva- tion of STAT3 in cancer cells is recognized as a promising strategy to be associated to anticancer therapies. Many synthetic and natu- ral P-STAT3 inhibitors have been described in vitro, while no clini- cal studies have been published to date [7]. In physiological conditions, JAK2 activation results from eryth- ropoietin (EPO)-, interleukine (IL)6-, IL10- or interferon (IFN)-gam- ma receptor stimulation. The mutated form of JAK2, namely JAK2V617F is observed in 95% of patients with Philadelphia chro- mosome-negative myeloproliferative neoplasms, polycythemia vera and essential thrombocythemia and myelofibrosis [8–11]. This mutation makes the kinase hypersensitive or independent of hematopoietic cytokines. The substitution V617F is located within the Jak homology 2 (JH2) domain of the protein, which is a pseudo- kinase. JH2 domain regulates associated receptor phosphorylation through auto-inhibitory properties, which are abolished in the mu- tated protein. Consequently, mutated JAK2 continuously activates signaling pathways including PI3K/AKT, ERK/MAPK pathways and 0304-3835/$ - see front matter Ó 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.canlet.2013.06.023 ⇑ Corresponding author. Tel.: +82 2 880 8919. E-mail address: marcdiederich@snu.ac.kr (M. Diederich). Cancer Letters xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Cancer Letters journal homepage: www.elsevier.com/locate/canlet Please cite this article in press as: A. Trécul et al., Polyphenol tri-vanillic ester 13c inhibits P-JAK2V617F and Bcr–Abl oncokinase expression in correlation with STAT3/STAT5 inactivation and apoptosis induction in human leukemia cells, Cancer Lett. (2013), http://dx.doi.org/10.1016/j.canlet.2013.06.023