Developmental pathways associated with cancer metastasis: Notch, Wnt, and Hedgehog

Master developmental pathways, such as Notch, Wnt, and Hedgehog, are signaling systems that control proliferation, cell death, motility, migration, and stemness. These systems are not only commonly activated in many solid tumors, where they drive or contribute to cancer initiation, but also in primary and metastatic tumor development. The reactivation of developmental pathways in cancer stroma favors the development of cancer stem cells and allows their maintenance, indicating these signaling pathways as particularly attractive targets for efficient anticancer therapies, especially in advanced primary tumors and metastatic cancers. Metastasis is the worst feature of cancer development. This feature results from a cascade of events emerging from the hijacking of epithelial-mesenchymal transition, angiogenesis, migration, and invasion by transforming cells and is associated with poor survival, drug resistance, and tumor relapse. In the present review, we summarize and discuss experimental data suggesting pivotal roles for developmental pathways in cancer development and metastasis, considering the therapeutic potential. Emerging targeted antimetastatic therapies based on Notch, Wnt, and Hedgehog pathways are also discussed

SLEEP AND WAKE ALTERATIONS IN AFRICAN TRYPANOSOMIASIS: FUNCTIONAL AND HISTOPATHOLOGICAL STUDY

La tripanosomiasi umana africana (human African trypanosomiasis o HAT), denominata anche malattia del sonno, è una grave malattia infiammatoria causata dal parassita Trypanosoma brucei (T.b.). Questa patologia, che è una tipica malattia “negletta”, è caratterizzata da alterazioni della struttura del sonno e dell’alternanza sonno-veglia. Il primo stadio, emolinfatico, della malattia, evolve nel secondo stadio, meningoencefalitico, quando il parassita T.b. attraversa la barriera emato-encefalica (BEE) ed invade il paraenchima cerebrale. I meccanismi patogenetici delle alterazioni neurologiche causate dall’infezione, così come la diagnosi di stadio quando il paziente si presenta all’osservazione e l’evoluzione della malattia rivestono alte valenze traslazionali poiché hanno importanti implicazioni diagnostiche e terapeutiche. Gli studi sulla tripanosomiasi africana che vengono presentati in questa tesi si articolano in 4 parti. Il primo studio sperimentale si è focalizzato, in ratti e topi infettati sperimentalmente con T.b. brucei, sull’orexina, un neuropeptide che svolge un ruolo chiave nel mantenimento dello stato di veglia e nelle transizioni sonno-veglia, e su un altro peptide, il melanin-concentrating hormone (MCH), implicato nella regolazione del sonno. Lo studio immunocitochimico ha rivelato una diminuzione, in una fase avanzata dell’infezione, sia delle cellule ipotalamiche che esprimono orexina che di quelle che esprimono MCH. L’indagine del livello di orexina nel liquor dei ratti infetti non ha, tuttavia, documentato alterazioni significative di tale parametro nel corso dell’infezione, indicando quindi che la concentrazione di orexina nel liquor non è un parametro atto a fornire un biomarcatore della malattia. Di particolare interesse patogenetico è il dato, rivelato da questo stesso studio, di un’alterata regolazione dell’attività dei neuroni orexinergici (valutata mediante l’oscillazione spontanea, nelle 24h, dell’espressione di Fos in tali cellule) durante il giorno e la notte. Il progetto si è poi rivolto alla ricerca, nell’infezione sperimentale nel ratto, di alterazioni funzionali che possano riflettere (e quindi consentire di svelare) il passaggio del T.b. attraverso la BEE. L’evoluzione temporale dell’infiltrazione di parassiti e linfociti nel parenchima encefalico è stata indagata mediante marcature immunoistochimiche multiple. Questa sperimentazione ha rivelato che l’ingresso del parassita e delle cellule T si verifica prevalentemente attraverso l’ipotalamo posteriore. Tale dato suggerisce differenze regionali di permeabilità della BEE dovute a segnali infiammatori nel corso dell’infezione, così come una potenziale vulnerabilità a questi eventi di gruppi neuronali implicati nella regolazione del sonno e della veglia. Gli stati di sonno e veglia ed i cicli della temperatura corporea e attività-riposo nelle 24h sono stati quindi monitorati di continuo, in ratti infetti, mediante registrazione telemetrica e paragonati con gli stessi parametri in condizioni basali prima dell’infezione. Analisi dettagliate di questa messe di dati hanno rivelato che alterazioni della struttura del sonno iniziano precocemente dopo l’infezione e precedono la neuroinvasione del parassita. Tali dati hanno svelato, inoltre, i parametri temporali dell’insorgenza e della progressione di alterazioni del sonno e della veglia, così come dei ritmi della temperatura corporea e attività-riposo, e le loro caratteristiche nel corso dell’infezione. Le analisi degli ipnogrammi ed actogrammi degli animali infetti hanno dimostrato che le alterazioni del ritmo attività-riposo possono fornire misurazioni attendibili delle alterazioni di sonno e veglia nel corso dell’infezione. Questo studio ha aperto la strada all’ultima parte del progetto, attuata in collaborazione con l’Università di Yaoundé 1 (Cameroon), nella quale sono state analizzate registrazioni actigrafiche e polisonnografiche di pazienti affetti da HAT. E’ stato così determinato che l’actigrafia può fornire, in questa patologia, un utile strumento di indagine atto a monitorare la gravità della malattia, aprendo così nuove prospettive per la valutazione clinica dei pazienti.Human African trypanosomiasis (HAT), also called sleeping sickness, is a neglected, severe neuroinflammatory disease caused by the protozoan Trypanosoma brucei (T.b.), and is characterized by alterations of the sleep pattern and sleep-wake cycle. The first, hemolymphatic stage of the disease evolves into the second, meningoencephalitic stage when T.b. cross the blood-brain barrier (BBB) and invade the brain parenchyma. Pathogenetic mechanisms of brain dysfunction caused by the infection, as well as knowledge of disease stage timing and evolution, are of high relevance also from the translational point of view given their diagnostic and therapeutic implications. The present doctoral studies on African trypanosomiasis have been articulated in 4 steps. The first investigation focused on orexin, a neuropeptide which plays a key role in wakefulness and in stabilizing sleep-wake transitions, as well as melanin concentrating hormone (MCH), which plays a role in sleep regulation, in rats and mice infected with T.b. brucei. Immunocytochemical study of orexin and MCH revealed a decrease, at an advanced stage of infection, of hypothalamic cells expressing either peptides; orexin level in the cerebrospinal fluid was not, however, significantly affected, and thus cannot provide a disease biomarker. Interestingly, day/night activity (as shown by Fos expression) of orexin-containing neurons was found to be deregulated in infected animals. Further steps of the project focused on search for functional changes which could reflect T.b. passage across the BBB, and these were investigated in the above rat model. The timing of parasite neuroinvasion and T-cell recruitment in the brain parenchyma was determined in multiple labeling immunocytochemical investigations. This part of the study revealed a prevalence of both parasite and T-cell entry through the posterior hypothalamus, suggesting regional differences in BBB permeability due to inflammatory signaling during the infection, and a potential vulnerability of hypothalamic sleep-wake regulatory cell groups to these events. Sleep-wake stages, core body temperature and rest-activity during 24 h were then continuously monitored in infected rats with telemetric recording and compared to baseline data. Extensive analyses of such data revealed that sleep structure alterations start early after the infection and precede parasite neuroinvasion, and showed then the onset and progression of distinct changes of wake and sleep states, as well as of body temperature and rest-activity rhythms. Furthermore, analyses of the hypnograms and actograms of the infected animals showed that rest-activity changes can provide reliable measurements of sleep-wake alterations. This paved the way to the last part of the project, pursued in collaboration with the University of Yaoundé 1 (Cameroon), in which hypnograms and actigraphic recordings of HAT patients have been analyzed. It has thus been determined that actigraphy can provides a useful tool for disease severity monitoring, opening novel perspectives for the clinical evaluation of patients with a non-invasive technique

Effect of inflammatory challenge on hypothalamic neurons expressing orexinergic and melanin-concentrating hormone

Neurons containing the hypothalamic peptides orexin-A (hypocretin 1) and melanin-concentrating hormone (MCH) have been reported numerous roles in the regulation of the sleep-wake cycle, energy balance and feeding behavior. We investigated the response of these cells to repeated administration of low doses of endotoxin lipopolysaccharide (LPS) in mice. Adult male C57/6J mice where intraperitoneally (i.p.) injected with either LPS or phosphate-buffered saline (PBS) weekly for either 4 or 8 weeks, and afterwards were sacrificed at different time intervals from last injection. A significant drop in orexin-containing neuron number, but not in numbers of MCH or neuronal nuclear antigen (NeuN)-immunoreactive neurons, was observed after 8 weeks of LPS treatment, as compared to PBS treatment. Orexin expression entirely returned to control levels 30 days after the last LPS injection in mice treated for 8 weeks. These data strongly suggest the occurrence of selective alterations of orexinergic system, reversible over time, following repeated and intermittent systemic inflammatory challenge in mice

Mesenchymal stromal cells’ role in tumor microenvironment: involvement of signaling pathways

International audienceMesenchymal stromal cells (MSCs) are adult multipotent stem cells residing as pericytes in various tissues and organs where they can differentiate into specialized cells to replace dying cells and damaged tissues. These cells are commonly found at injury sites and in tumors that are known to behave like " wounds that do not heal." In this article, we discuss the mechanisms of MSCs in migrating, homing, and repairing injured tissues. We also review a number of reports showing that tumor microenvironment triggers plasticity mechanisms in MSCs to induce malignant neoplastic tissue formation, maintenance, and chemoresistance, as well as tumor growth. The antitumor properties and therapeutic potential of MSCs are also discussed

Sleep and rhythm changes at the time of Trypanosoma brucei invasion of the brain parenchyma in the rat.

Human African trypanosomiasis (HAT), or sleeping sickness, is a severe disease caused by Trypanosoma brucei (T.b.). The disease hallmark is sleep alterations. Brain involvement in HAT is a crucial pathogenetic step for disease diagnosis and therapy. In this study, a rat model of African trypanosomiasis was used to assess changes of sleep-wake, rest-activity, and body temperature rhythms in the time window previously shown as crucial for brain parenchyma invasion by T.b. to determine potential biomarkers of this event. Chronic radiotelemetric monitoring in Sprague-Dawley rats was used to continuously record electroencephalogram, electromyogram, rest-activity, and body temperature in the same animals before (baseline recording) and after infection. Rats were infected with T.b. brucei. Data were acquired from 1 to 20 d after infection (parasite neuroinvasion initiates at 11-13 d post-infection in this model), and were compared to baseline values. Sleep parameters were manually scored from electroencephalographic-electromyographic tracings. Circadian rhythms of sleep time, slow-wave activity, rest-activity, and body temperature were studied using cosinor rhythmometry. Results revealed alterations of most of the analyzed parameters. In particular, sleep pattern and sleep-wake organization plus rest-activity and body temperature rhythms exhibited early quantitative and qualitative alterations, which became marked around the time interval crucial for parasite neuroinvasion or shortly after. Data derived from actigrams showed close correspondence with those from hypnograms, suggesting that rest-activity could be useful to monitor sleep-wake alterations in African trypanosomiasis

Stromal control of chronic lymphocytic leukemia cells

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Signaling pathways in breast cancer: Therapeutic targeting of the microenvironment

Breast cancer is the most common cancer in women worldwide. Understanding the biology of this malignant disease is a prerequisite for selecting an appropriate treatment. Cell cycle alterations are seen in many cancers, including breast cancer. Newly popular targeted agents in breast cancer include cyclin dependent kinase inhibitors (CDKIs) which are agents inhibiting the function of cyclin dependent kinases (CDKs) and agents targeting proto-oncogenic signaling pathways like Notch, Wnt, and SHH (Sonic hedgehog). CDKIs are categorized as selective and non-selective inhibitors of CDK. CDKIs have been tried as monotherapy and combination therapy. The CDKI Palbocyclib is now a promising therapeutic in breast cancer. This drug recently entered phase III trial for estrogen receptor (ER) positive breast cancer after showing encouraging results in progression free survival in a phase II trials. The tumor microenvironment is now recognized as a significant factor in cancer treatment response. The tumor microenvironment is increasingly considered as a target for combination therapy of breast cancer. Recent findings in the signaling pathways in breast cancer are herein summarized and discussed. Furthermore, the therapeutic targeting of the microenvironment in breast cancer is also considered