Paola Picardi

The endocannabinoid signaling system in cancer

Changes in lipid metabolism are intimately related to cancer. Several classes of bioactive lipids play roles in the regulation of signaling pathways involved in neoplastic transformation and tumor growth and progression. The endocannabinoid system, comprising lipid-derived endocannabinoids, their G-protein-coupled receptors (GPCRs), and the enzymes for their metabolism, is emerging as a promising therapeutic target in cancer. This report highlights the main signaling pathways for the antitumor effects of the endocannabinoid system in cancer and its basic role in cancer pathogenesis, and discusses the alternative view of cannabinoid receptors as tumor promoters. We focus on new players in the antitumor action of the endocannabinoid system and on emerging crosstalk among cannabinoid receptors and other membrane or nuclear receptors involved in cancer. We also discuss the enzyme MAGL, a key player in endocannabinoid metabolism that was recently recognized as a marker of tumor lipogenic phenotype.

Genetic and pharmacologic inactivation of cannabinoid CB1 receptor inhibits angiogenesis.

In this study we investigated the role of CB1 receptor signaling in angiogenesis and the therapeutic exploitation of CB1 inactivation as an antiangiogenic strategy. We started from the observation that CB1 receptor expression is induced during angiogenesis and that the endocannabinoid anandamide stimulated bFGF-induced angiogenesis in the nanomolar physiologic range. To define the functional involvement of CB1 receptor signaling during angiogenesis, 2 different strategies have been carried out: siRNA-mediated knockdown and pharmacologic antagonism of CB1 receptors. CB1 receptors inactivation resulted in the inhibition of bFGF-induced endothelial proliferation, migration, and capillary-like tube formation, through prosurvival and migratory pathways involving ERK, Akt, FAK, JNK, Rho, and MMP-2. To corroborate the potential therapeutic exploitation of CB1 blockade as an antiangiogenic strategy, we performed in vivo assays founding that CB1 blockade was able to inhibit bFGF-induced neovascular growth in the rabbit cornea assay. A relevant finding was the ability to reduce ocular pathologic neo-vascularization in mouse oxygen-induced retinopathy. These results demonstrate that CB1 signaling participates to the proliferative response elicited by proangiogenic growth factors in angiogenesis and that for this reason CB1 receptor could represent a novel target for the treatment of diseases where excessive neoangiogenesis is the underlying pathology.

Novel prospects of statins as therapeutic agents in cancer.

Statins are well known competitive inhibitors of hydroxymethylglutaryl-CoA reductase enzyme (HMG-CoA reductase), thus traditionally used as cholesterol-lowering agents. In recent years, more and more effects of statins have been revealed. Nowadays alterations of lipid metabolism have been increasingly recognized as a hallmark of cancer cells. Consequently, much attention has been directed toward the potential of statins as therapeutic agents in the oncological field. Accumulated in vitro and in vivo clinical evidence point out the role of statins in a variety of human malignancies, in regulating tumor cell growth and anti-tumor immune response. Herein, we summarize and discuss, in light of the most recent observations, the anti-tumor effects of statins, underpinning the detailed mode of action and looking for their true significance in cancer prevention and treatment, to determine if and in which case statin repositioning could be really justified for neoplastic diseases.

Bendamustine and rituximab combination is safe and effective as salvage regimen in Waldenström macroglobulinemia

According to the European Society for Medical Oncology and National Comprehensive Cancer Network guidelines on Waldenström macroglobulinemia, bendamustine (B) may be considered a suitable therapeutic option. To address the role of B in combination with rituximab (BR), we analyzed the outcome of 71 patients with relapsed/refractory disease, median age 72 years, treated with R 375 mg/m2 day 1 and B days 1 and 2 (dosage ranging from 50 to 90 mg/m2). Patients had previously received a median number of 2 lines of treatment (range 1–5). Overall and major response rates were 80.2% and 74.6%. Major toxicity was grade 3/4 neutropenia occurring in 13% of courses. There was no significant association between baseline features or patients’ characteristics and response achievement. Median progression-free survival was not reached after a median follow-up of 19 months (range 3–54). None of the patients developed aggressive lymphoma or secondary myelodysplastic syndrome/acute myeloid leukemia. BR was found to be an active and well-tolerated salvage regimen leading to rapid disease control.

Efficacy and safety of pegylated liposomal doxorubicin in primary cutaneous B-cell lymphomas and comparison with the commonly used therapies

Objectives:  The therapy of advanced, relapsed or refractory primary cutaneous lymphomas is often unsatisfactory. Recent data indicate a favourable pharmacokynetic, pharmacodynamic and toxicity profile of pegylated liposomal doxorubicin (Peg‐Doxo) in primary cutaneous T‐cell lymphomas, while in primary cutaneous B‐cell lymphomas (PCBCLs), the drug efficacy has never been assessed so far.

N6‐isopentenyladenosine, an endogenous isoprenoid end product, directly affects cytotoxic and regulatory functions of human NK cells through FDPS modulation

iPA is a naturally occurring nucleoside with an isopentenyl moiety derived from the mevalonate pathway and a well‐established anti‐tumor activity. In analogy to the unique specificity for phosphoantigens, such as IPP, shown by human Vγ9Vδ2 T cells, here, we report for the first time the ability of iPA to selectively expand and directly target human NK cells. Interestingly, submicromolar doses of iPA stimulate resting human NK cells and synergize with IL‐2 to induce a robust activation ex vivo with significant secretion of CCL5 and CCL3 and a large increase in TNF‐α and IFN‐γ production when compared with IL‐2 single cytokine treatment. Moreover, iPA promotes NK cell proliferation and up‐regulates the expression of specific NK cell‐activating receptors, as well as CD69 and CD107a expression. Accordingly, this phenotype correlates with significantly greater cytotoxicity against tumor targets. At the molecular level, iPA leads to a selective, potent activation of MAPK signaling intermediaries downstream of the IL‐2R. The effect results, at least in part, from the fine modulation of the FDPS activity, the same enzyme implicated in the stimulation of the human γδ T cells. The iPA‐driven modulation of FDPS can cause an enhancement of post‐translational prenylation essential for the biological activity of key proteins in NK signaling and effector functions, such as Ras. These unanticipated properties of iPA provide an additional piece of evidence of the immunoregulatory role of the intermediates of the mevalonate pathway and open novel therapeutic perspectives for this molecule as an immune‐modulatory drug.

Antiangiogenic effects of N6-isopentenyladenosine, an endogenous isoprenoid end product, mediated by AMPK activation

N6‐isopentenyladenosine (iPA), an end product of the mevalonate pathway with an isopentenyl chain, is already known to exert a suppressor effect against various tumors. In this work, we investigated whether iPA also directly interferes with the angiogenic process, which is fundamental to tumor growth and progression. To this end, using human umbilical vein endothelial cells (HUVECs) as a suitable in vitro model of angiogenesis, we evaluated their viability, proliferation, migration, invasion, tube formation in response to iPA, and molecular mechanisms involved. Data were corroborated in mice by using a gel plug assay. iPA dose‐ and time‐dependently inhibited all the neoangiogenesis stages, with an IC50 of 0.98 μM. We demonstrated for the first time, by liquid chromatography–coupled tandem mass spectrometry (LC‐MS/MS), that iPA was monophosphorylated into 5′‐iPA‐monophosphate (iPAMP) by the adenosine kinase (ADK) inside the cells. iPAMP is the active form that inhibits angiogenesis through the direct activation of AMP‐kinase (AMPK). Indeed, all effects were completely reversed by pretreatment with 5‐iodotubercidin (5‐Itu), an ADK inhibitor. The isoprenoid intermediate isopentenyl pyrophosphate (IPP), which shares the isopentenyl moiety with iPA, was ineffective in the inhibition of angiogenesis, thus showing that the iPA structure is specific for the observed effects. In conclusion, iPA is a novel AMPK activator and could represent a useful tool for the treatment of diseases where excessive neoangiogenesis is the underlying pathology.—Pisanti, S., Picardi, P., Ciaglia, E., Margarucci, L., Ronca, R., Giacomini, A., Malfitano, A. M., Casapullo, A., Laezza, C., Gazzerro, P., Bifulco, M. Antiangiogenic effects of N6‐isopentenyladenosine, an endogenous isoprenoid end‐product, mediated by AMPK activation. FASEB J. 28, 1132–1144 (2014). www.fasebj.org

N6-isopentenyladenosine affects cytotoxic activity and cytokines production by IL-2 activated NK cells and exerts topical anti-inflammatory activity in mice

N6-isopentenyladenosine (iPA) is a modified adenosine with an isopentenyl moiety derived from the mevalonate pathway which displays pleiotropic biological effects, including anti-tumor and anti-angiogenic activity. Previous evidence revealed a biphasic effect of iPA on phytohemagglutinin-stimulated lymphocytes, being pro-proliferative at low doses and anti-proliferative at high doses. Analogously, we have recently shown that low iPA concentrations (<1μM) increased the immune response of natural killer (NK) cells against cancer targets. In the present study, we evaluated the effect of iPA at high concentration (10μM) on IL-2-activated NK cells. iPA, inhibited NK cell proliferation and cytotoxicity against their conventional tumor target, human K562 cells. This inhibition was associated with decreased expression and functionality of NK cell activating receptors NKp44 and NKG2D as well as impaired cyto/chemokines secretion (RANTES, MIP-1α, TNF-α and IFN-γ). ERK/MAPK and STAT5 activation in IL-2-activated NK cells were inhibited by iPA. The results obtained in vitro were validated in vivo in the inflammatory murine model of croton oil-induced ear dermatitis. The topical application of iPA significantly reduced mouse ear oedema, thus suggesting anti-inflammatory properties of this molecule. These results show the ability of iPA to exert anti-inflammatory effects both in vitro and in vivo directly targeting NK cells, providing a novel pharmacological tool in those diseases characterized by a deregulated immune-response, such as cancer or inflammatory conditions.

High-dose therapy followed by stem cell transplantation in Hodgkin’s lymphoma: past and future

Hodgkin’s lymphoma (HL) has been a fascinating challenge for physicians and investigators since its recognition during the 19th century. However, many questions still remain unanswered. One issue regards high-dose therapy followed by autologous stem cell transplantation (ASCT), which has yet to find its place among several guidelines. Other topics are still controversial with respect to transplantation for HL, including its role for newly diagnosed patients with advanced stage disease, the optimal timing of transplantation, the best conditioning regimen and the role of allogeneic/haploidentical SCT. Moreover, the potential use of localized radiotherapy or immunologic methods to decrease post-transplant recurrence, the role of novel agents such as brentuximab vedotin and their positioning in the treatment algorithm of resistant/relapsed HL patients, either before transplant to boost salvage therapy or after transplant as consolidation/maintenance, are burning questions without an answer. In this review, the authors try to give an answer to some of these dilemmas.

Anandamide drives cell cycle progression through CB1 receptors in a rat model of synchronized liver regeneration.

The endocannabinoid system, through cannabinoid receptor signaling by endocannabinoids, is involved in a wide range of functions and physiopathological conditions. To date, very little is known concerning the role of the endocannabinoids in the control and regulation of cell proliferation. An anti‐proliferative action of CB1 signaling blockade in neurogenesis and angiogenesis argues in favor of proliferation‐promoting functions of endocannabinoids through CB1 receptors when pro‐growth signals are present. Furthermore, liver regeneration, a useful in vivo model of synchronized cell proliferation, is characterized by a peak of anandamide that elicits through CB1 receptor, the expression of critical mitosis genes. The aim of this study was to focus on the timing of endocannabinoid signaling changes during the different phases of the cell cycle, exploiting the rat liver regeneration model following partial hepatectomy, the most useful to study synchronized cell cycle in vivo. Hepatic regeneration led to increased levels of anandamide and endocannabinoid‐like molecules oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) in the G1 phase of the cell cycle, with a concomitant increase in CB1 mRNA levels, whose protein expression peaked later during the S phase. Blocking of CB1 receptor with a low dose of the selective antagonist/inverse agonist SR141716 (0.7 mg/kg/dose) affected cell cycle progression reducing the expression of PCNA, and through the inhibition of pERK and pSTAT3 pathways. These results support the notion that the signaling mediated by anandamide through CB1 receptor may be important for the entry and progression of cells into the cell cycle and hence for their proliferation under mitogenic signals. J. Cell. Physiol. 230: 2905–2914, 2015.