STUDIO DEI MECCANISMI DI MORTE CELLULARI INDOTTI DAL CANNABINOIDE SINTETICO WIN IN CELLULE TUMORALI IN COLTURA

Per lungo tempo, i cannabinoidi sono stati considerati come farmaci lenitivi ma non curativi della patologia cancerosa. Tuttavia, negli scorsi anni, è stata suggerita una potenziale applicazione dei cannabinoidi come droghe antitumorali, anche se il loro meccanismo d’azione non è ancora ben conosciuto. Gli obiettivi di questo studio sono stati: - la valutazione degli effetti del cannabinoide sintetico WIN55,212-2 (WIN) su differenti linee di cellule tumorali in coltura (cellule di carcinoma colorettale HT29 e cellule di osteosarcoma umano MG63) e – la valutazione dei meccanismi molecolari indotti dal trattamento con il cannabinoide. I risultati riportati indicano che in entrambe le linee cellulari il WIN è in grado di indurre stress del reticolo endoplasmatico e autofagia, ma gli effetti del trattamento sulla vitalità cellulare sono differenti. In particolare, in cellule di carcinoma colorettale il WIN attiva il pathway apoptotico, mentre in cellule di osteosarcoma gli effetti del WIN non sono associati al meccanismo apoptotico classico e, soltanto l’aggiunta di TRAIL è in grado di indurre a morte le cellule. L’analisi dei meccanismi molecolari attivati dal trattamento con il WIN nei due modelli sperimentali ha mostrato che il percorso autofagico innescato dal WIN ha significato opposto: nelle cellule di carcinoma colorettale rappresenta un tentativo della cellula di opporsi all’azione del WIN, mentre in osteosarcoma l’autofagia facilita il realizzarsi dell’apoptosi. Ciò potrebbe essere legato al coinvolgimento di differenti “attori molecolari” nei due modelli sperimentali

WIN-induced vesiculation cooperates to the inhibition of osteosarcoma cell migration

Introduction. Animal cells release vesicles that mediate the secretion of a variety of factors in the surrounding environment affecting neighboring cells. There is increasing evidence that secreted vesicles play an important role as vehicle of intercellular communication in different biological systems and are able to influence both physiological and pathological processes. Recently, we have reported that the synthetic cannabinoid WIN55,512 is able to induce osteosarcoma MG63 cell death and negatively affect cell migration. Here, we study the effects of WIN on the induction of vesicle secretion and their possible role in WIN-dependent reduction of osteosarcoma cell migratory ability. Methods. Vesicles from MG63 cells were obtained by ultracentrifuging at 140,000g media derived from cell cultures untreated and treated for 24 h with 5 uM WIN. Purified vesicles were quantified by cytofluorimetry and by detecting acetilcholinesterase activity according to established criteria. Scratch wound healing assay was employed to monitor cell migration toward the center of a gap created in a cell monolayer. Zymographic analysis was used to evaluate metalloproteinase activities in the vesicles. Results. WIN treatment induced a significant increase (about 4-fold) in the number of vesicles released by osteosarcoma cells. Wound healing assay showed that in the presence of vesicles from WIN-treated cultures, cells only partially filled the gap with respect to those conditioned with vesicles isolated from control cells which closed the gap within about 24 h. Furthermore, zymography assay showed a reduced activity of MMP-2 and MMP-9 in the vesicles obtained from WIN-treated cells. Conclusion. Data indicate that the increase in the number of vesicles released after WIN treatment and/or their probable different composition can be responsible for the relevant inhibition of MG63 cell migration induced by the cannabinoid

The Histone Deacetylase Inhibitor ITF2357 (Givinostat) Targets Oncogenic BRAF in Melanoma Cells and Promotes a Switch from Pro-Survival Autophagy to Apoptosis

Histone deacetylase inhibitors (HDACI) are epigenetic compounds that have been widely considered very promising antitumor agents. Here, we focus on the effects of the pan-HDAC inhibitor ITF2357 (Givinostat) in comparison with SAHA (Vorinostat) in melanoma cells bearing BRAF V600E oncogenic mutation. Our results indicate both ITF2357 and SAHA dose-dependently reduce the viability of BRAF-mutated SK-MEL-28 and A375 melanoma cells. The comparison of IC50 values revealed that ITF2357 was much more effective than SAHA. Interestingly, both inhibitors markedly decreased oncogenic BRAF protein expression levels, ITF2357 being the most effective compound. Moreover, the BRAF decrease induced by ITF2357 was accompanied by a decrease in the level of phospho-ERK1/2. The inhibitor of upstream MEK activity, U0126, reduced ERK1/2 phosphorylation and dramatically potentiated the antitumor effect of ITF2357, exacerbating the reduction in the BRAF level. ITF2357 stimulated an early pro-survival autophagic response, which was followed by apoptosis, as indicated by apoptotic markers evaluation and the protective effects exerted by the pan-caspase inhibitor z-VADfmk. Overall, our data indicate for the first time that ITF2357 targets oncogenic BRAF in melanoma cells and induces a switch from autophagy to classic apoptosis, thus representing a possible candidate in melanoma targeted therapy

Involvement of PAR-4 in Cannabinoid-Dependent Sensitization of Osteosarcoma Cells to TRAIL-Induced Apoptosis

The synthetic cannabinoid WIN 55,212-2 is a potent cannabinoid receptor agonist with anticancer potential. Experiments were performed to determine the effects of WIN on proliferation, cell cycle distribution, and programmed cell death in human osteosarcoma MG63 and Saos-2 cells. Results show that WIN induced G2/M cell cycle arrest, which was associated with the induction of the main markers of ER stress (GRP78, CHOP and TRB3). In treated cells we also observed the conversion of the cytosolic form of the autophagosome marker LC3-I into LC3-II (the lipidated form located on the autophagosome membrane) and the enhanced incorporation of monodansylcadaverine and acridine orange, two markers of the autophagic compartments such as autolysosomes. WIN also induced morphological effects in MG63 cells consisting in an increase in cell size and a marked cytoplasmic vacuolization. However, WIN effects were not associated with a canonical apoptotic pathway, as demonstrated by the absence of specific features, and only the addition of TRAIL to WIN-treated cells led to apoptotic death probably mediated by up-regulation of the tumor suppressor factor PAR-4, whose levels increased after WIN treatment, and by the translocation of GRP78 on cell surface

Autophagic cell death induced by Litchi fruit extracts in human colon cancer cells.

Litchi chinensis is a tropical fruit which cultivation has been recently introduced in Sicily. Some findings have shown that Litchi extracts display antitumor effects but the underlying mechanisms have not been elucidated. This study focuses on the effects of Litchi hydro-alcoholic extracts in colorectal cancer cells. The results indicated that Litchi exocarp (peel), mesocarp (pulp) and endocarp (seeds) extracts reduce the viability of HT-29 colon cancer cells in a dose dependent manner. This effect was accompanied with G2/M arrest of the cell cycle followed by cell death. Interestingly, exocarp and endocarp extracts triggered an autophagic response in the first phase of treatment (16-24h) with increase in the protein levels of ATG1/ Ulk kinase, p62 and LC3-II accumulation. In particular, time point evaluation indicated that with exocarp extracts the autophagic form LC3II appeared at 16h treatment whereas with endocarp extracts accumulated at 48h. ATG1/Ulk and p62 increased early at 16 h treatment in both cases and p62 remained elevated until 48h. On the other hand, autophagic effects were not observed with Litchi mesocarp extracts which directly induced caspase 3-dependent apoptosis. Polyphenol colorimetric assay showed that the Litchi extracts contain significant amounts of these compounds, particularly in exocarp and endocarp. Accordingly, treatment of cells with gallic acid, one bioactive component of polyphenols, mimicked the effects of the Litchi extracts. Taken together, these preliminary results provides in vitro evidence that litchi extracts activate the autophagic process preceding cell death and can thus be considered as potential chemopreventive agents for colorectal cancer

Oncogenic BRAF and p53 Interplay in Melanoma Cells and the Effects of the HDAC Inhibitor ITF2357 (Givinostat)

Oncogenic BRAF mutations have been widely described in melanomas and promote tumour progression and chemoresistance. We previously provided evidence that the HDAC inhibitor ITF2357 (Givinostat) targets oncogenic BRAF in SK-MEL-28 and A375 melanoma cells. Here, we show that oncogenic BRAF localises to the nucleus of these cells, and the compound decreases BRAF levels in both the nuclear and cytosolic compartments. Although mutations in the tumour suppressor p53 gene are not equally frequent in melanomas compared to BRAF, the functional impairment of the p53 pathway may also contribute to melanoma development and aggressiveness. To understand whether oncogenic BRAF and p53 may cooperate, a possible interplay was considered in the two cell lines displaying a different p53 status, being p53 mutated into an oncogenic form in SK-MEL-28 and wild-type in A375 cells. Immunoprecipitation revealed that BRAF seems to preferentially interact with oncogenic p53. Interestingly, ITF2357 not only reduced BRAF levels but also oncogenic p53 levels in SK-MEL-28 cells. ITF2357 also targeted BRAF in A375 cells but not wild-type p53, which increased, most likely favouring apoptosis. Silencing experiments confirmed that the response to ITF2357 in BRAF-mutated cells depends on p53 status, thus providing a rationale for melanoma-targeted therapy

Parthenolide and Its Soluble Analogues: Multitasking Compounds with Antitumor Properties

Due to its chemical properties and multiple molecular effects on different tumor cell types, the sesquiterpene lactone parthenolide (PN) can be considered an effective drug with significant potential in cancer therapy. PN has been shown to induce either classic apoptosis or alternative caspase-independent forms of cell death in many tumor models. The therapeutical potential of PN has been increased by chemical design and synthesis of more soluble analogues including dimethylaminoparthenolide (DMAPT). This review focuses on the molecular mechanisms of both PN and analogues action in tumor models, highlighting their effects on gene expression, signal transduction and execution of different types of cell death. Recent findings indicate that these compounds not only inhibit prosurvival transcriptional factors such as NF-κB and STATs but can also determine the activation of specific death pathways, increasing intracellular reactive oxygen species (ROS) production and modifications of Bcl-2 family members. An intriguing property of these compounds is its specific targeting of cancer stem cells. The unusual actions of PN and its analogues make these agents good candidates for molecular targeted cancer therapy

Hypertrophy and ER Stress Induced by Palmitate Are Counteracted by Mango Peel and Seed Extracts in 3T3-L1 Adipocytes

A diet rich in saturated fatty acids (FAs) has been correlated with metabolic dysfunction and ROS increase in the adipose tissue of obese subjects. Thus, reducing hypertrophy and oxidative stress in adipose tissue can represent a strategy to counteract obesity and obesity-related diseases. In this context, the present study showed how the peel and seed extracts of mango (Mangifera indica L.) reduced lipotoxicity induced by high doses of sodium palmitate (PA) in differentiated 3T3-L1 adipocytes. Mango peel (MPE) and mango seed (MSE) extracts significantly lowered PA-induced fat accumulation by reducing lipid droplet (LDs) and triacylglycerol (TAGs) content in adipocytes. We showed that MPE and MSE activated hormone-sensitive lipase, the key enzyme of TAG degradation. In addition, mango extracts down-regulated the adipogenic transcription factor PPARγ as well as activated AMPK with the consequent inhibition of acetyl-CoA-carboxylase (ACC). Notably, PA increased endoplasmic reticulum (ER) stress markers GRP78, PERK and CHOP, as well as enhanced the reactive oxygen species (ROS) content in adipocytes. These effects were accompanied by a reduction in cell viability and the induction of apoptosis. Interestingly, MPE and MSE counteracted PA-induced lipotoxicity by reducing ER stress markers and ROS production. In addition, MPE and MSE increased the level of the anti-oxidant transcription factor Nrf2 and its targets MnSOD and HO-1. Collectively, these results suggest that the intake of mango extract-enriched foods in association with a correct lifestyle could exert beneficial effects to counteract obesity

Foodomics-Based Approaches Shed Light on the Potential Protective Effects of Polyphenols in Inflammatory Bowel Disease

nflammatory bowel disease (IBD) is a chronic and progressive inflammatory disorder affecting the gastrointestinal tract (GT) caused by a wide range of genetic, microbial, and environ- mental factors. IBD is characterized by chronic inflammation and decreased gut microbial diversity, dysbiosis, with a lower number of beneficial bacteria and a concomitant increase in pathogenic species. It is well known that dysbiosis is closely related to the induction of inflammation and oxidative stress, the latter caused by an imbalance between reactive oxygen species (ROS) production and cellular antioxidant capacity, leading to cellular ROS accumulation. ROS are responsible for intestinal epithelium oxidative damage and the increased intestinal permeability found in IBD patients, and their reduction could represent a potential therapeutic strategy to limit IBD progression and alleviate its symptoms. Recent evidence has highlighted that dietary polyphenols, the natural antioxidants, can maintain redox equilibrium in the GT, preventing gut dysbiosis, intestinal epithelium damage, and radical inflammatory responses. Here, we suggest that the relatively new foodomics approaches, together with new technologies for promoting the antioxidative properties of dietary polyphenols, including novel delivery systems, chemical modifications, and combination strategies, may provide critical insights to determine the clinical value of polyphenols for IBD therapy and a comprehensive perspective for implementing natural antioxidants as potential IBD candidate treatment

The Antitumor Potential of Sicilian Grape Pomace Extract: A Balance between ROS-Mediated Autophagy and Apoptosis

From the perspective of circular economy, it is extremely useful to recycle waste products for human health applications. Among the health-beneficial properties of bioactive phyto-compounds, grape pomace represents a precious source of bioactive molecules with potential antitumor properties. Here, we describe the effects of a Sicilian grape pomace hydroalcoholic extract (HE) in colon and breast cancer cells. The characterization of HE composition revealed the predominance of anthoxanthins and phenolic acids. HE treatment was more effective in reducing the viability of colon cancer cells, while breast cancer cells appeared more resistant. Indeed, while colon cancer cells underwent apoptosis, as shown by DNA fragmentation, caspase-3 activation, and PARP1 degradation, breast cancer cells seemed to not undergo apoptosis. To elucidate the underlying mechanisms, reactive oxygen species (ROS) were evaluated. Interestingly, ROS increased in both cell lines but, while in colon cancer, cells' ROS rapidly increased and progressively diminished over time, in breast cancer, cells' ROS increase was persistent up to 24 h. This effect was correlated with the induction of pro-survival autophagy, demonstrated by autophagosomes formation, autophagic markers increase, and protection by the antioxidant NAC. The autophagy inhibitor bafilomycin A1 significantly increased the HE effects in breast cancer cells but not in colon cancer cells. Overall, our data provide evidence that HE efficacy in tumor cells depends on a balance between ROS-mediated autophagy and apoptosis. Therefore, inhibiting pro-survival autophagy may be a tool to target those cells that appear more resistant to the effect of HE