Biomedical subjects

Paola Giuliano

Publications and source records attributed to Paola Giuliano.

5 recordsLinked to original sources

PubMed2006

Human melanoma metastases express functional CXCR4.

PURPOSE: The chemokine receptor CXCR4 was identified as an independent predictor of poor prognosis in primary melanoma. The aim of the study was to investigate the role of CXCR4 in human melanoma metastases. EXPERIMENTAL DESIGN: CXCR4 expression was evaluated in melanoma metastases and in metastatic cell lines through immunohistochemistry, immunoblotting, immunofluorescence, and reverse transcription-PCR. The function of CXCR4 was tested in the presence of the ligand, CXCL12, through induction of extracellular signal-regulated kinase-1 and -2 (Erk-1 and -2) phosphorylation, proliferation, apoptosis, and migration capabilities. RESULTS: CXCR4 expression was detected in 33 out of 63 (52.4%) metastases from cutaneous melanomas. Metastatic melanoma cell lines expressed cell surface CXCR4; PES 43, Alo 40, and COPA cell lines showed the highest levels of CXCR4 (>90% of positive cells); PES 41, Alo 39, PES 47, POAG, and CIMA cell lines showed low to moderate degrees of expression (5-65% of positive cells). Other chemokine receptors, CCR7 and CCR10, were detected on the melanoma cell lines; CXCL12 activated Erk-1 and Erk-2, the whose induction was specifically inhibited by AMD3100 treatment. CXCL12 increased the growth in PES 41, PES 43, and PES 47 cells under suboptimal (1% serum) and serum-free culture conditions; AMD3100 (1 mumol/L) inhibited the spontaneous and CXCL12-induced proliferation. No rescue from apoptosis was shown but PES 41, PES 43, and PES 47 cells migrate toward CXCL12. CONCLUSIONS: These findings indicate that CXCR4 is expressed and active in human melanoma metastases, suggesting that active inhibitors such as AMD3100 may be experienced in human melanoma.

Benzylamines↗

PubMed2006

Huntingtin inclusion bodies are iron-dependent centers of oxidative events.

Recently, we reported that the transient expression of huntingtin exon1 polypeptide containing polyglutamine tracts of various sizes (httEx1-polyQ) in cell models of Huntington disease generated an oxidative stress whose intensity was CAG repeat expansion-dependent. Here, we have analyzed the intracellular localization of the oxidative events generated by the httEx1-polyQ polypeptides. Analysis of live COS-7 cells as well as neuronal SK-N-SH and PC12 cells incubated with hydroethidine or dichlorofluorescein diacetate revealed oxidation of these probes at the level of the inclusion bodies formed by httEx1-polyQ polypeptides. The intensity and frequency of the oxidative events among the inclusions were CAG repeat expansion-dependent. Electron microscopic analysis of cell sections revealed the presence of oxidation-dependent morphologic alterations in the vicinity of httEx1-polyQ inclusion bodies. Moreover, a high level of oxidized proteins was recovered in partially purified inclusions. We also report that the iron chelator deferroxamine altered the structure, localization and oxidative potential of httEx1-polyQ inclusion bodies. Hence, despite the fact that the formation of inclusion bodies may represent a defense reaction of the cell to eliminate httEx1 mutant polypeptide, this phenomenon appears inherent to the generation of iron-dependent oxidative events that can be deleterious to the cell.

Acetylcysteine↗

PubMed2005

Expression of CXCR4 predicts poor prognosis in patients with malignant melanoma.

PURPOSE: CXCR4 receptor and its unique ligand, the CXCL12 chemokine, have been recently implicated in cancer metastasis. Evidence about the role of CXCR4/CXCL12 axis has been reported in several cancers including melanoma. Our goal was to investigate if CXCR4 expression has a prognostic value in malignant melanoma. EXPERIMENTAL DESIGN: Immunohistochemical expression of CXCR4 was evaluated on 71 specimens of primary cutaneous melanoma with a Breslow tumor thickness of >1 mm after radical resection. Associations between baseline patient features and tumors were analyzed by chi(2) test. The prognostic value of CXCR4 expression was evaluated by univariate and multivariate analyses adjusted by age, sex, Breslow tumor thickness, presence of ulceration, and sentinel lymph node metastases. RESULTS: CXCR4 expression was detected in 31 of 71 (43.6%) primary cutaneous melanomas. Membrane or cytoplasmic staining for CXCR4 protein was absent in 56% of the tumors. The positive cases were divided into three score classes according to their staining: low in 15 cases (21%), moderate in 10 (14%), and high in 6 (8%). After a median follow-up of 38 months, 26 patients progressed (16 of 26 expressed CXCR4) and 19 died (12 of 19 expressed CXCR4). The CXCR4 expression on tumor cells was correlated with an unfavorable prognosis with a median disease-free and overall survival of 22 and 35 months, respectively. The hazard ratios of relapse and death, compared with patients with CXCR4-negative tumors, were 2.5 (95% confidence interval, 1.2-6.1) and 3.1 (95% confidence interval, 1.1-7.2), respectively. Median time-to-event (progression and survival) was not reached in patients with CXCR4-negative tumors. In the multivariate analysis, CXCR4 expression, presence of ulceration, and sentinel lymph node status emerged as independent prognostic factors. CONCLUSIONS: This article provides the first evidence that CXCR4 expression could be an independent and powerful prognostic marker in primary cutaneous malignant melanomas.

Age Factors↗

PubMed2003

DNA damage induced by polyglutamine-expanded proteins.

We have developed stable cell lines expressing green fluorescent protein fusion proteins containing polyglutamine repeats of various lengths under tetracycline control. The expression of the expanded (43Q) repeat protein resulted in aggregate formation in a time-dependent fashion. The accumulation of aggregates did not induce apoptosis, although the survival of these cells was critically dependent on the presence of serum and growth factors. However, the expression of 43Q expanded protein strongly activated the ataxia telangiectasia mutated kinase/ATM and Rad3-related kinase (ATM/ATR)-dependent DNA damage response, as shown by selective phosphorylation of ATM substrates. This activation was dependent on 43 CAG protein expression, reversible and sensitive to caffeine and reducing agents. Similarly, we found phosphorylated ATM substrates in fibroblasts from Huntington's disease or SCA-2 patients. Oxidative stress induced accumulation of ATM/ATR phosphorylated protein in HD and SCA-2 patients, but not in normal controls. Furthermore, a significant phosphorylation of H2AX was shown by fibroblasts from patients. We conclude that polyglutamine induces ATM/ATR-dependent DNA damage response through accumulation of reactive oxygen species. ATM activation can be used to monitor the disease in vivo.

Amino Acid Sequence↗

PubMed2002

Up-regulation of c-Jun N-terminal kinase pathway in Friedreich's ataxia cells.

The severe reduction in mRNA and protein levels of the mitochondrial protein frataxin, encoded by the X25 gene, causes Friedreich ataxia (FRDA), the most common form of recessive hereditary ataxia. Increasing evidence underlines the pathogenetic role of oxidative stress in this disease. We generated an in vitro cellular model of regulated human frataxin overexpression. We identified, by differential display technique, the mitogen activated protein kinase kinase 4 mRNA down regulation in frataxin overexpressing cells. We studied the stress kinases pathway in this cellular model and in fibroblasts from FRDA patients. Frataxin overexpression reduced c-Jun N-terminal kinase phosphorylation. Furthermore, exposure of FRDA fibroblasts to several forms of environmental stress caused an up regulation of phospho-JNK and phospho-c-Jun. To understand if this susceptibility results in cell death, we have investigated the involvement of caspases. A significantly higher activation of caspase-9 was observed in FRDA versus control fibroblasts after serum-withdrawal. Our findings suggest the presence, in FRDA patient cells, of a 'hyperactive' stress signaling pathway. The role of frataxin in FRDA pathogenesis could be explained, at least in part, by this hyperactivity.

Animals↗