Mechanism of the mesenchymal-epithelial transition and its relationship with metastatic tumor formation

Cancer metastasis consists of a sequential series of events, and the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are recognized as critical events for metastasis of carcinomas. A current area of focus is the histopathological similarity between primary and metastatic tumors, and MET at sites of metastases has been postulated to be part of the process of metastatic tumor formation. Here, we summarize accumulating evidence from experimental studies that directly supports the role of MET in cancer metastasis, and we analyze the main mechanisms that regulate MET or reverse EMT in carcinomas. Given the critical role of MET in metastatic tumor formation, the potential to effectively target the MET process at sites of metastasis offers new hope for inhibiting metastatic tumor formation.     

Metastatic spread: mechanisms and therapies

Although metastatic spread is the most frequent cause of deaths in cancer patients, there are very few drugs specifically targeting this process. Bases for a new antimetastatic drug discovery strategy are weak because a great number of unknowns characterizes the whole understanding of the metastatic cascade mechanisms. Moreover, the current experimental models are too simplistic and do not account for the complexity of the phenomenon. Some targets have been identified but too few are validated. Among them, metastasis suppressor genes seem to be the most promising. In spite of this, during the last years, a dozen of molecules which fulfill the definition of a specific metastatic drug, namely that inhibit metastases without altering growth of the primary tumor (which can be eradicated by surgery), have been identified and tried out to assess the proof of the concept. The continuation of this effort would be more efficient if the objectives were defined more precisely. It is particularly important to distinguish molecules aimed at preventing metastic cell spreading at the primary tumour early stage and molecules which have to induce a regression of established metastases or to inhibit the transition from disseminated occult tumour cells to dormant micrometastasis. This second goal is a priori more relevant in the current clinical setting where detection of the early metastatic spread is very difficult, and therefore it should focus a greater effort of the scientific community.     

Changes in the Na, K-ATPase of neuronal membranes in penicillin-induced epileptic foci in the cerebral cortex of the rat]

The relationship between electrophysiological changes and Na, K-ATPase activity of neuronal membranes in sodium penicillin-induced epileptic foci was studied. Na,K-ATPase activity is inhibited both in the primary focus and in homotopic contralateral area during latent period and in the stage of forming epileptic activity. In the stage of marked convulsive activity Na, K-ATPase is inhibited only in the primary focus. It is shown that penicillin at a concentration range of 2 x 10(-6)--2 x 10(-3) M does not influence Na,K-ATPase activity of crude synaptosomes of the rat brain cortex. It is suggested that Na,K-ATPase inactivation may serve as a pathogenetic factor in the development of convulsive process.     

Type IV pilus retraction enables sustained bacteremia and plays a key role in the outcome of meningococcal sepsis in a humanized mouse model

Neisseria meningitidis (the meningococcus) remains a major cause of bacterial meningitis and fatal sepsis. This commensal bacterium of the human nasopharynx can cause invasive diseases when it leaves its niche and reaches the bloodstream. Blood-borne meningococci have the ability to adhere to human endothelial cells and rapidly colonize microvessels. This crucial step enables dissemination into tissues and promotes deregulated inflammation and coagulation, leading to extensive necrotic purpura in the most severe cases. Adhesion to blood vessels relies on type IV pili (TFP). These long filamentous structures are highly dynamic as they can rapidly elongate and retract by the antagonistic action of two ATPases, PilF and PilT. However, the consequences of TFP dynamics on the pathophysiology and the outcome of meningococcal sepsis in vivo have been poorly studied. Here, we show that human graft microvessels are replicative niches for meningococci, that seed the bloodstream and promote sustained bacteremia and lethality in a humanized mouse model. Intriguingly, although pilus-retraction deficient N. meningitidis strain (ΔpilT) efficiently colonizes human graft tissue, this mutant did not promote sustained bacteremia nor induce mouse lethality. This effect was not due to a decreased inflammatory response, nor defects in bacterial clearance by the innate immune system. Rather, TFP-retraction was necessary to promote the release of TFP-dependent contacts between bacteria and, in turn, the detachment from colonized microvessels. The resulting sustained bacteremia was directly correlated with lethality. Altogether, these results demonstrate that pilus retraction plays a key role in the occurrence and outcome of meningococcal sepsis by supporting sustained bacteremia. These findings open new perspectives on the role of circulating bacteria in the pathological alterations leading to lethal sepsis.     

The mechanisms of the porphyrin conformation of normal blood hemoglobin and in pathology]

The spectra of resonance Raman scattering of blood in norm and under pathology (myocardial infarction and sepsis), as well after artificial hemotransfusion or UV photomodification have been studied. It has been shown that under heart pathology the structure of hemoglobin porphyrin macrocycle of erythrocytes changes, the size of porphyrin "nucleus" increases. The opposite conditions are observed at blood sepsis. It has been found that the traditional methods in tissue restoration, hemotransfusion and UV photomodification of blood don't result in complete restoration of hemoporphyrin molecule.     

Role of platelets and breast cancer stem cells in metastasis

The high mortality rate of breast cancer is mainly caused by the metastatic ability of cancer cells, resistance to chemotherapy and radiotherapy, and tumor regression capacity. In recent years, it has been shown that the presence of breast cancer stem cells is closely associated with the migration and metastatic ability of cancer cells, as well as with their resistance to chemotherapy and radiotherapy. The tumor microenvironment is one of the main molecular factors involved in cancer and metastatic processes development, in this sense it is interesting to study the role of platelets, one of the main communicator cells in the human body which are activated by the signals they receive from the microenvironment and can generate more than one response. Platelets can ingest and release RNA, proteins, cytokines and growth factors. After the platelets interact with the tumor microenvironment, they are called "tumor-educated platelets." Tumor-educated platelets transport material from the tumor microenvironment to sites adjacent to the tumor, thus helping to create microenvironments conducive for the development of primary and metastatic tumors. It has been observed that the clone capable of carrying out the metastatic process is a cancer cell with stem cell characteristics. Cancer stem cells go through a series of processes, including epithelial-mesenchymal transition, intravasation into blood vessels, movement through blood vessels, extravasation at the site of the establishment of a metastatic focus, and site colonization. Tumor-educated platelets support all these processes.     

Molecular mechanisms of Streptococcus dysgalactiae subsp equisimilis enabling intravascular persistence

Streptococcus dysgalactiae subsp. equisimilis (SDSE) can cause recurrent bacteremic infection. We have characterized novel virulence properties of an SDSE isolate of type stG485.0 that caused severe sepsis three times in a patient despite that he had opsonizing antibodies to the isolate. An infected aortic aneurysm was suspected to be the focus for the persisting bacteria. For the first time we show that this SDSE isolate, as well as other invasive SDSE isolates, aggregate human platelets and efficiently internalize into human endothelial cells. These properties may aid SDSE to persist and could explain the tendency of SDSE to cause recurrent bacteremia.     

Model systems: modeling human staphylococcal arthritis and sepsis in the mouse.

The staphylococci have been recognized as serious pathogens for over a century and are the etiological agent of a variety of diseases ranging from mild cutaneous infections to often fatal forms of septic arthritis, endocarditis, toxic shock syndrome and sepsis. Despite intensive efforts to halt their spread, they remain the most common cause of community- and nosocomially acquired bacteremia. Murine models of Staphylocococus aureus-mediated arthritis and sepsis exist and are being used to gain a better understanding of the host-bacterium relationship as well to develop better methods of prevention and treatment.     

EphrinB reverse signaling in cell-cell adhesion

Cell-cell adhesion is a critical process for the formation and maintenance of tissue patterns during development, as well as invasion and metastasis of cancer cells. Although great strides have been made regarding our understanding of the processes that play a role in cell-cell adhesion, the precise mechanisms by which diverse signaling events regulate cell and tissue architecture is poorly understood. In this commentary we will focus on the Eph/ephrin signaling system, and specifically how the ephrinB1 transmembrane ligand for Eph receptor tyrosine kinases sends signals affecting cell-cell junctions. In a recent study using the epithelial cells of early stage Xenopus embryos, we have shown that loss- or gain-of function of ephrinB1 can disrupt cell-cell contacts and tight junctions. This study reveals a mechanism where ephrinB1 competes with active Cdc42 for binding to Par-6, a scaffold protein central to the Par polarity complex (Par-3/Par-6/Cdc42/aPKC) and disrupts the localization of tight junction-associated proteins (ZO-1, Cingulin) at tight junctions. This competition reduces aPKC activity critical to maintaining and/or forming tight junctions. Finally, phosphorylation of ephrinB1 on specific tyrosine residues can block the interaction between ephrinB1 and Par-6 at tight junctions, and restore tight junction formation. Recent evidence indicates that de-regulation of forward signaling through EphB receptors may play a role in metastatic progression in colon cancer. In light of the new data showing an effect of ephrinB reverse signaling on tight junctions, an additional mechanism can be hypothesized where de-regulation of ephrinB1 expression or phosphorylation may also impact metastatic progression.     

The phenomenon of HLA antigen modification in meningococcal infection

212 patients with the generalized forms of meningococcal infection have been examined. The intensity and quality of lymphocytotoxic reaction in the acute phase and the convalescence period of the disease have been analyzed and the blank calculation has been made at different clinical forms of meningococcal infection. The formation of modified tissue antigens at the acute stage of the disease in the presence of intoxication is shown and the probable role of the intensity of bacteremia in this formation is discussed.     

GTPase activating protein function of p85 facilitates uptake and recycling of the β1 integrin

β1-containing adhesions at the plasma membrane function as dynamic complexes to provide bidirectional communication between the cell and its environment, yet commonly are used by pathogens to gain host cell entry. Recently, the cholesterol-lowering drug simvastatin was found to inhibit host invasion through β1-containing adhesion complexes. To better understand the regulatory mechanisms controlling adhesion formation and uptake and the use of these complexes by Staphylococcus aureus, the primary etiologic agent in sepsis, bacteremia and endocarditis, we investigated the mechanism of inhibition by simvastatin. In response to simvastatin, adhesion complexes diminished as well as β1 trafficking to the plasma membrane required to initiate adhesion formation. Simvastatin stimulated CDC42 activation and coupling to p85, a small-guanosine triphosphatase (GTPase) activating protein (GAP), yet sequestered CDC42 coupled to p85 within the cytosol. Loss of p85 GAP activity through use of genetic strategies decreased host cell invasion as well as β1 trafficking. From these findings, we propose a mechanism whereby p85 GAP activity localized within membrane compartments facilitates β1 trafficking. By sequestering p85 within the cytosol, simvastatin restricts the availability and uptake of the receptor used by pathogenic strains to gain host cell entry.     

Regulation of microRNAs in cancer metastasis

Metastasis is a phenomenon of crucial importance in defining prognosis in patients with cancer and is often responsible for cancer-related mortality. It is known that several steps are necessary for clonal cells to disseminate from their primary tumor site and colonize distant tissues, thus originating metastatic lesions. Therefore, investigating the molecular actors regulating this process may provide helpful insights in the development of efficient therapeutic responses. Recent evidences have indicated the role of microRNAs (miRNAs) in modulating the metastatic process in solid tumors. miRNAs are small regulatory non-coding RNAs that bind to specific target mRNAs, leading to translational repression. miRNAs are known to act as negative regulators of gene expression and are involved in the regulation of biological processes, including cell growth, differentiation and apoptosis, both in physiological conditions and during diseases, such as tumors. In the specific field of tumorigenesis, miRNAs play an important role in mediating oncogenesis and favoring tumor progression, as a result of their ability to modulate epithelial-to-mesenchymal transition (EMT) and other series of events facilitating the formation of metastasis. The role of miRNAs in cancer development has been widely studied and has helped elucidate events such as the change in expression of oncogenes, tumor-suppressors and cancer-related proteins. This review focuses on the mechanisms underlying the role of miRNAs as part of the metastatic process.     

Increased interleukin-10 levels correlate with bacteremia and sepsis in febrile neutropenia pediatric oncology patients

BackgroundEarly diagnosis of bacteremia and sepsis in pediatric oncology patients with febrile neutropenia still remains unresolved task due to lack of sensitive and specific laboratory markers particularly at the beginning of the infectious process. The objective of our study was to assess the potentiality of interleukin-10 (IL-10) to predict or exclude bacteremia or sepsis at the beginning of febrile episode in childhood oncology patients.MethodsA total of 36 febrile neutropenic episodes in 24 children were studied. Serum samples were collected after confirmation of febrile neutropenia and analyzed using automated random access analyzer.ResultsThe sensitivity of IL-10 was 73% and specificity – 92% (cut-off = 18 pg/ml, area under the curve – 0.87, 95% CI for sensitivity 39–94%, 95% CI for specificity 74–99%) with negative predictive value (NPV) – 83%.ConclusionsIL-10 evaluation might be used as an additional diagnostic tool for clinicians in excluding bacteremia or clinical sepsis in oncology patients with febrile neutropenia because of high NPV and specificity.     

Novel structurally designed vaccine for S. aureus α-hemolysin: protection against bacteremia and pneumonia

Staphylococcus aureus (S. aureus) is a human pathogen associated with skin and soft tissue infections (SSTI) and life threatening sepsis and pneumonia. Efforts to develop effective vaccines against S. aureus have been largely unsuccessful, in part due to the variety of virulence factors produced by this organism. S. aureus alpha-hemolysin (Hla) is a pore-forming toxin expressed by most S. aureus strains and reported to play a key role in the pathogenesis of SSTI and pneumonia. Here we report a novel recombinant subunit vaccine candidate for Hla, rationally designed based on the heptameric crystal structure. This vaccine candidate, denoted AT-62aa, was tested in pneumonia and bacteremia infection models using S. aureus strain Newman and the pandemic strain USA300 (LAC). Significant protection from lethal bacteremia/sepsis and pneumonia was observed upon vaccination with AT-62aa along with a Glucopyranosyl Lipid Adjuvant-Stable Emulsion (GLA-SE) that is currently in clinical trials. Passive transfer of rabbit immunoglobulin against AT-62aa (AT62-IgG) protected mice against intraperitoneal and intranasal challenge with USA300 and produced significant reduction in bacterial burden in blood, spleen, kidney, and lungs. Our Hla-based vaccine is the first to be reported to reduce bacterial dissemination and to provide protection in a sepsis model of S. aureus infection. AT62-IgG and sera from vaccinated mice effectively neutralized the toxin in vitro and AT62-IgG inhibited the formation of Hla heptamers, suggesting antibody-mediated neutralization as the primary mechanism of action. This remarkable efficacy makes this Hla-based vaccine a prime candidate for inclusion in future multivalent S. aureus vaccine. Furthermore, identification of protective epitopes within AT-62aa could lead to novel immunotherapy for S. aureus infection.     

The key role of extracellular vesicles in the metastatic process

Extracellular vesicles (EVs), including exosomes, have a key role in the paracrine communication between organs and compartments. EVs shuttle virtually all types of biomolecules such as proteins, lipids, nucleic acids, metabolites and even pharmacological compounds. Their ability to transfer their biomolecular cargo into target cells enables EVs to play a key role in intercellular communication that can regulate cellular functions such as proliferation, apoptosis and migration. This has led to the emergence of EVs as a key player in tumor growth and metastasis through the formation of “tumor niches” in target organs. Recent data have also been shown that EVs may transform the microenvironment of primary tumors thus favoring the selection of cancer cells with a metastatic behavior. The release of EVs from resident non-malignant cells may contribute to the metastatic processes as well. However, cancer EVs may induce malignant transformation in resident mesenchymal stem cells, suggesting that the metastatic process is not exclusively due to circulating tumor cells. In this review, we outline and discuss evidence-based roles of EVs in actively regulating multiple steps of the metastatic process and how we can leverage EVs to impair metastasis.     

Sputum cytology of metastatic carcinoma of the lung.

The cytopathology of 47 cases of metastatic carcinoma of the lung and of 28 cases of recurrent or metastatic bronchogenic carcinoma is reviewed. The diagnostic yield was better for recurrent than for metastatic carcinoma but overall was comparable to that of primary bronchogenic carcinomas. The metastatic tumors were located in all areas of the lung and included single as well as multiple lesions. The positive yield did not differ significantly in relation to any of the pathologic features but was somewhat higher if the metastases were large and centrally located. A definite differentiation of the metastatic tumors, usually adenocarcinomas, from new primary bronchogenic carcinomas is often possible particularly if the cytopathology can be compared with that of the primary lesion. Specific cytologic features include the relative lack of cohesion and the formation of columns in metastatic breast carcinomas, the formation of larger cohesive well circumscribed nodules composed of tall columnar cells in metastatic colon carcinomas, clear cell features in some metastatic adenocarcinomas of the kidney, and the small cell size and uniform, regular nuclear features in the often cytologically well differentiated metastatic carcinomas of the prostate.     

生物喋呤的生物学效应及其在脓毒症中的意义

研究表明,一氧化氮（ＮＯ）的过度产生可能是诱发脓毒性休克的最后共同通路,而生物喋呤为一氧化氮合酶（ＮＯＳ）重要的辅因子。多种免疫刺激因子均可诱导细胞内ＢＨ４合成显著增加,其可瑟ＮＯＳ紧密结合,调控ＮＯ的合成与释放。本文讨论了ＢＨ４的生物学效应,调控机制及其在脓毒症中的作用,并简要介绍其合成抑制剂在脓毒症防治中的潜在意义。     

Growth and metastasis of Lewis' lung carcinoma in mice under the pharmacological action on metabolism and the effects of kinins

In experiments on C57 Bl mice the effects of growth and metastatic proliferation of Lewis lung carcinoma inoculated intramuscularly on metabolism and kinin activity have been studied during the application of pharmacologic agents (parmidin, cellulose sulphate, unithiol). Causing a weak inhibition of the primary tumour growth, parmidin if administered repeatedly in given doses, inhibits partially metastatic process, which is manifested in an essential decrease of the quantity, size and weight of lung metastases. Parmidin also inhibits an adverse effect of cellulose sulphate and unithiol on metastatic process. It is believed that the action of parmidin is of an indirect character and is mainly associated with the elimination of the kinin component of microcirculatory disorders in the lungs.