Brain tumor stem cell dancing

Background. Issues regarding cancer stem cell (CSC) movement are important in neu-rosphere biology as cell-cell or cell-environment interactions may have significant impacts on CSC differentiation and contribute to the heterogeneity of the neurosphere. Aims. Despite the growing body of literature data on the biology of brain tumor stem  cells, floating CSC-derived neurospheres have been scarcely characterized from a morphological and ultrastructural point of view. Results. Here we report a morphological and ultrastructural characterization performed  by  live  imaging  and  scanning  electron  microscopy.  Glioblastoma  multiforme  (GBM)  CSC-derived neurospheres are heterogeneous and are constituted by cells, morphologically different, capable of forming highly dynamic structures. These dynamic structures  are regulated by not serendipitous cell-cell interactions, and they synchronously pulsate  following a cyclic course made of “fast” and “slow” alternate phases. Autocrine/paracrine  non  canonical  Wnt  signalling  appears  to  be  correlated  with  the  association  status  of  neurospheres. Conclusions. The results obtained suggest that GBM CSCs can behave both as independents cells and as “social” cells, highly interactive with other members of its species,  giving rise to a sort of “multicellular organism”.   

The multidrug transporter P-glycoprotein: A mediator of melanoma invasion?

Malignant melanoma shows high levels of intrinsic drug resistance associated with a highly invasive phenotype. In this study, we investigated the role of the drug transporter P-glycoprotein (Pgp) in the invasion potential of drug-sensitive (M14 WT, Pgp-negative) and drug-resistant (M14 ADR, Pgp-positive) human melanoma cells. Coimmunoprecipitation experiments assessed the association of Pgp with the adhesion molecule CD44 in multidrug resistant (MDR) melanoma cells, compared with parental ones. In MDR cells, the two proteins colocalized in the plasma membrane as visualized by confocal microscopy and immunoelectron microscopy on ultrathin cryosections. MDR melanoma cells displayed a more invasive phenotype compared with parental cells, as demonstrated by quantitative transwell chamber invasion assay. This was accomplished by a different migration strategy adopted by resistant cells ("chain collective") previously described in tumor cells with high metastatic capacity. The Pgp molecule, after stimulation with specific antibodies, appeared to cooperate with CD44, through the activation of ERK1/2 and p38 mitogen-activated protein kinase (MAPK) proteins. This activation led to an increase of metalloproteinase (MMP-2, MMP-3, and MMP-9) mRNAs, and proteolytic activities, which are associated with an increased invasive behavior. RNA interference experiments further demonstrated Pgp involvement in migration and invasion of resistant melanoma cells. A link was identified between MDR transporter Pgp, and MAPK signaling and invasion. © 2007 The Society for Investigative Dermatology

The Reverse Transcription Inhibitor Abacavir Shows Anticancer Activity in Prostate Cancer Cell Lines

Background: Transposable Elements (TEs) comprise nearly 45% of the entire genome and are part of sophisticated regulatory network systems that control developmental processes in normal and pathological conditions. The retroviral/ retrotransposon gene machinery consists mainly of Long Interspersed Nuclear Elements (LINEs-1) and Human Endogenous Retroviruses (HERVs) that code for their own endogenous reverse transcriptase (RT). Interestingly, RT is typically expressed at high levels in cancer cells. Recent studies report that RT inhibition by non-nucleoside reverse transcriptase inhibitors (NNRTIs) induces growth arrest and cell differentiation in vitro and antagonizes growth of human tumors in animal model. In the present study we analyze the anticancer activity of Abacavir (ABC), a nucleoside reverse transcription inhibitor (NRTI), on PC3 and LNCaP prostate cancer cell lines. Principal Findings: ABC significantly reduces cell growth, migration and invasion processes, considerably slows S phase progression, induces senescence and cell death in prostate cancer cells. Consistent with these observations, microarray analysis on PC3 cells shows that ABC induces specific and dose-dependent changes in gene expression, involving multiple cellular pathways. Notably, by quantitative Real-Time PCR we found that LINE-1 ORF1 and ORF2 mRNA levels were significantly up-regulated by ABC treatment. Conclusions: Our results demonstrate the potential of ABC as anticancer agent able to induce antiproliferative activity and trigger senescence in prostate cancer cells. Noteworthy, we show that ABC elicits up-regulation of LINE-1 expression, suggesting the involvement of these elements in the observed cellular modifications

Characterization of biofilms in drug-sensitive and drug-resistant strains of Candida albicans

In this study, we investigated the biofilm formation in strains of Candida albicans susceptible (CO23) or resistant to fluconazole (CO23RFLC) or micafungin (CO23RFK). The effect of drug resistance on biofilm formation was investigated through the cell surface hydrophobicity and the mannan content. Moreover, biofilm formation was evaluated after 24, 48 and 72 hours with crystal violet assay, dry weight, as well as scanning electron microscopy. Our results showed an increase in hydrophobicity, polysaccharides content, metabolic activity and dry weight. Observation of sensitive and resistant strains confirmed the differences in cell morphology. Finally, the expression of genes involved in biofilm formation, such as HWP1 and EFG1, evaluated with relative real-time RT-PCR. Resistant strains proved to up- regulate the expression of HWP1. These results demonstrated the existence of important differences between drug-susceptible and drug-resistant strains biofilm of C. albicans

Meccanismo di azione e proprietà terapeutiche dell’olio essenziale di Melaleuca alternifolia su ceppi farmacosensibili e farmacoresistenti di Candida albicans

Le malattie infettive sono causate da microrganismi che interagiscono in modo complesso con l’ospite. La scoperta degli antibiotici e il loro impiego sono risultati molto efficaci nel trattamento delle infezioni batteriche e fungine, ma il loro uso indiscriminato ha purtroppo causato lo sviluppo di ceppi patogeni resistenti. Infatti, negli ultimi anni le terapie anticancro (chemio e radio-terapia) e l’AIDS hanno pesantemente contribuito all’aggravarsi dell’immunocompromissione dei pazienti che vivono a lungo in questo stato. Difatti, in questi pazienti sono ricorrenti le infezioni fungine localizzate e sistemiche e per prevenire l’evolversi di tali patologie viene incrementato l’uso di farmaci antimicotici anche per la profilassi. Purtroppo, con l’uso eccessivo di questi farmaci si è registrato anche un significativo incremento dei fenomeni di resistenza agli antimicotici (1). Storicamente la resistenza clinica è stata definita come persistenza o progressione di un’infezione nonostante la terapia antimicrobica appropriata. Una successiva risposta clinica alla terapia antimicrobica, tipicamente, non solo dipende dalla suscettibilità dell’organismo patogeno, ma molto dal suo sistema immunitario, dalla penetrazione e distribuzione del farmaco e da complicanze nel paziente. La resistenza in vitro di un isolato può essere descritta come primaria o secondaria. Un organismo che risulta resistente ad un farmaco prima dell’esposizione presenta resistenza primaria intrinseca. La resistenza secondaria si sviluppa in risposta all’esposizione ad agenti antimicotici (2). Una correlazione di suscettibilità rivelata in vitro con quella riscontrata in vivo, è stata osservata per infezioni mucosali di Candida in pazienti HIV positivi (3). Candida albicans (C. albicans) è un fungo diploide che vive solitamente come colonizzatore innocuo e commensale del tratto gastrointestinale e genitale dell’uomo, oppure come patogeno opportunista in presenza di uno o più fattori predisponenti (4). La sua patogenicità è dovuta alla capacità di invadere tessuti e organi e di dar luogo a difficili, talvolta intrattabili, infezioni superficiali. Anche l’abilità di C. albicans nel formare biofilm sulle superfici (cellule endoteliali e cateteri) è considerata responsabile della “resistenza clinica”. È noto infatti, che la formazione dei biofilms può conferire protezione al microrganismo all’interno degli strati, portando al fallimento della terapia antimicotica (5)

Increase of Virulence and Its Phenotypic Traits in Drug-Resistant Strains of Candida albicans▿

There is concern about the rise of antifungal drug resistance, but little is known about comparative biological properties and pathogenicity of drug-resistant strains. We generated fluconazole (FLC; CO23RFLC)- or micafungin (FK; CO23RFK)-resistant strains of Candida albicans by treating a FLC- and FK-susceptible strain of this fungus (CO23S) with stepwise-increasing concentrations of either drug. Molecular analyses showed that CO23RFLC had acquired markedly increased expression of the drug-resistance efflux pump encoded by the MDR1 gene, whereas CO23RFK had a homozygous mutation in the FSK1 gene. These genetic modifications did not alter to any extent the growth capacity of the drug-resistant strains in vitro, either at 28°C or at 37°C, but markedly increased their experimental pathogenicity in a systemic mouse infection model, as assessed by the overall mortality and target organ invasion. Interestingly, no apparent increase in the vaginopathic potential of the strains was observed with an estrogen-dependent rat vaginal infection. The increased pathogenicity of drug-resistant strains for systemic infection was associated with a number of biochemical and physiological changes, including (i) marked cellular alterations associated with a different expression and content of major cell wall polysaccharides, (ii) more rapid and extensive hypha formation in both liquid and solid media, and (iii) increased adherence to plastic and a propensity for biofilm formation. Overall, our data demonstrate that experimentally induced resistance to antifungal drugs, irrespective of drug family, can substantially divert C. albicans biology, affecting in particular biological properties of potential relevance for deep-seated candidiasis