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Biomedical subjects

Lucio Miele

Publications and source records attributed to Lucio Miele.

30 records · Page 2Linked to original sources
PubMed2004

p53-independent NOXA induction overcomes apoptotic resistance of malignant melanomas.

Once melanoma metastasizes, no effective treatment modalities prolong survival in most patients. This notorious refractoriness to therapy challenges investigators to identify agents that overcome melanoma resistance to apoptosis. Whereas many survival pathways contribute to the death-defying phenotype in melanoma, a defect in apoptotic machinery previously highlighted inactivation of Apaf-1, an apoptosome component engaged after mitochondrial damage. During studies involving Notch signaling in melanoma, we observed a gamma-secretase tripeptide inhibitor (GSI; z-Leu-Leu-Nle-CHO), selected from a group of compounds originally used in Alzheimer's disease, induced apoptosis in nine of nine melanoma lines. GSI only induced G2-M growth arrest (but not killing) in five of five normal melanocyte cultures tested. Effective killing of melanoma cells by GSI involved new protein synthesis and a mitochondrial-based pathway mediated by up-regulation of BH3-only members (Bim and NOXA). p53 activation was not necessary for up-regulation of NOXA in melanoma cells. Blocking GSI-induced NOXA using an antisense (but not control) oligonucleotide significantly reduced the apoptotic response. GSI also killed melanoma cell lines with low Apaf-1 levels. We conclude that GSI is highly effective in killing melanoma cells while sparing normal melanocytes. Direct enhancement of BH3-only proteins executes an apoptotic program overcoming resistance of this lethal tumor. Identification of a p53-independent apoptotic pathway in melanoma cells, including cells with low Apaf-1, bypasses an impediment to current cytotoxic therapy and provides new targets for future therapeutic trials involving chemoresistant tumors.

Annexin A5↗
PubMed2003

Notch signaling as a therapeutic target in cancer: a new approach to the development of cell fate modifying agents.

Notch signaling controls cell fate decisions including during development and stem cell renewal and differentiation in many postnatal tissues. Increasing evidence suggests that the Notch signaling network is frequently deregulated in human malignancies and that genetic or pharmacological manipulation of Notch signaling is a novel potential strategy for the treatment of human neoplasms. This review article summarizes the most recent preclinical and clinical evidence linking Notch signaling to cancer, delineates questions that remain unanswered and explores potential biopharmacological strategies to manipulate Notch signaling in vivo.

Animals↗
PubMed2003

TCR-mediated Notch signaling regulates proliferation and IFN-gamma production in peripheral T cells.

Notch genes encode membrane receptors that regulate cell fate decisions in metazoa. Notch receptors and ligands are expressed in developing lymphoid tissue and mature lymphocytes and the role of Notch signaling in early T and B cell development has been studied extensively. However, its contribution to mature T cell function is unknown. TCR-mediated T cell activation is a fundamental process of the adaptive immune system that has been studied for decades; however, the details of this process are incompletely understood. In this study, we present evidence that Notch is required for TCR-mediated activation of peripheral T cells. Inhibition of Notch activation dramatically decreases T cell proliferation in both CD4 and CD8 cells and blocks both NF-kappaB activity and IFN-gamma production in peripheral T cells. Our data reveal a new, nondevelopmental function of Notch as a previously unknown key link in peripheral T cell activation and cytokine secretion.

Amyloid Precursor Protein Secretases↗
PubMed2003

Notch signaling is necessary but not sufficient for differentiation of dendritic cells.

The Notch family of receptors plays an important role in regulation of cell differentiation via direct contact between hematopoietic progenitor cells (HPCs) and bone marrow stroma (BMS). However the precise contribution of Notch in dendritic cell (DC) differentiation is controversial. In 2 different experimental systems using Notch-1-null embryonic stem cells and Notch-1-deficient HPCs we have found that Notch-1 is necessary for DC differentiation. However, activation of Notch-1 and Notch-2 with cell-bound Notch ligand did not result in differentiation of mature DCs or macrophages. Instead, it caused accumulation of immature myeloid cells. Removal of feeder cells resulted in rapid differentiation of DCs and macrophages. Addition of interleukin 4 (IL-4) into the culture dramatically increased accumulation of functionally potent DCs. Lipopolysaccharide was not able to reproduce this effect. Thus, these data indicate that Notch signaling prevents differentiation of mature myeloid cells. Instead, it results in accumulation of precursors readily able to differentiate into mature DCs once the Notch signal is stopped (eg, after cell emigration from bone marrow) and in the presence of other additional differentiation signals provided by IL-4. Thus, Notch is required but not sufficient for DC differentiation.

Animals↗
PubMed2003

Notch-1 induction, a novel activity of SV40 required for growth of SV40-transformed human mesothelial cells.

We show that SV40 infection of human mesothelial cells directly causes overexpression of Notch-1, a key cell regulatory gene. Notch-1 induction is achieved at the transcriptional level and requires both the SV40 large T-antigen and the small t-antigen. Notch-1 upregulation is maintained in SV40-transformed human mesothelial clones and in SV40-positive mesotheliomas and derived cell lines. Activation of Notch-1 promotes cell cycle progression and it is required for the growth of SV40-transformed mesothelial cells. Our finding is relevant to the process of SV40-mediated human cell transformation, an effect that cannot be accounted for solely by SV40-Tag inhibition of Rb and p53.

Cell Line, Transformed↗
PubMed2003

HPV16 E6 and E7 oncoproteins regulate Notch-1 expression and cooperate to induce transformation.

Notch receptor signaling has been implicated in cellular transformation. Notch-1 receptor expression is increased during the progression from cervical intraepithelial lesions (CIN) to invasive cervical carcinoma. Moreover, the main cellular localization of Notch-1 protein changes from cytoplasmic to nuclear with the transition from CIN III to microinvasive carcinoma. Since the E6 and E7 proteins encoded by human papilloma virus (HPV) are a causative agent of cervical carcinoma, this study determined whether E6 and E7 protein expression causes the observed upregulation in Notch-1 expression. Mouse and human primary cell lines were transfected with HPV16 E6 and E7 and Notch-1 expression and activity were analyzed. We show that Notch-1 expression and activity are upregulated by E6 and E7 independently. This was due to both transcriptional and post-transcriptional mechanisms. A protein involved in Notch processing, Presenilin-1 (PS-1), was also upregulated by E6 and E7. In the presence of E6 and E7, Notch-1 protein expression is localized in the cytoplasm. Downregulation of Notch-1 expression in a human cervical carcinoma cell line expressing E6/E7 caused striking inhibition of proliferation in vitro and tumorigenicity in vivo. These data suggest that E6- and E7-mediated upregulation of Notch signaling may contribute to disruption of regular cell growth in cervical cancer.

Animals↗
PubMed2002

The Notch ligand Jagged-1 is able to induce maturation of monocyte-derived human dendritic cells.

Notch receptors play a key role in several cellular processes including differentiation, proliferation, and apoptosis. This study investigated whether the activation of Notch signaling would affect the maturation of dendritic cells (DCs). Direct stimulation of Notch signaling in DCs with a peptide ligand induced DC maturation, similar to LPS: DCs up-regulated maturation markers, produced IL-12, lost endocytosis capacity, and became able to activate allogeneic T cells. Furthermore, coculture of DCs with cells expressing Notch ligand Jagged-1 induced up-regulation of maturation markers, IL-12 production, T cell proliferative responses, and IFN-gamma production. Our data suggest that activation of Notch by Jagged-1 plays an important role in maturation of human DCs. Additionally, they reveal a novel role for Notch signaling in cell maturation events distal to the cell fate decision fork. These data may have important medical implications, since they provide new reagents to induce DC activity, which may be beneficial as adjuvants in situations where an immune response needs to be elicited, such as tumor immunotherapy.

Amino Acid Sequence↗
PubMed2002

Activation of Notch-1 signaling maintains the neoplastic phenotype in human Ras-transformed cells.

Truncated Notch receptors have transforming activity in vitro and in vivo. However, the role of wild-type Notch signaling in neoplastic transformation remains unclear. Ras signaling is deregulated in a large fraction of human malignancies and is a major target for the development of novel cancer treatments. We show that oncogenic Ras activates Notch signaling and that wild-type Notch-1 is necessary to maintain the neoplastic phenotype in Ras-transformed human cells in vitro and in vivo. Oncogenic Ras increases levels and activity of the intracellular form of wild-type Notch-1, and upregulates Notch ligand Delta-1 and also presenilin-1, a protein involved in Notch processing, through a p38-mediated pathway. These observations place Notch signaling among key downstream effectors of oncogenic Ras and suggest that it might be a novel therapeutic target.

Animals↗
PubMed2002

Lys 43 and Asp 46 in alpha-helix 3 of uteroglobin are essential for its phospholipase A2 inhibitory activity.

Uteroglobin (UG) is an anti-inflammatory, secreted protein with soluble phospholipase A2 (sPLA2)-inhibitory activity. However, the mechanism by which UG inhibits sPLA2 activity is unknown. UG is a homodimer in which each of the 70-amino acid subunits forms four alpha-helices. We previously reported that sPLA2-inhibitory activity of UG may reside in a segment of alpha-helix 3 that is exposed to the solvent. In addition, it has been suggested that UG may inhibit sPLA2 activity by binding and sequestering Ca++, essential for sPLA2 activation. By site-specific mutation, we demonstrate here that Lys 43 Glu, Asp 46 Lys or a combination of the two mutations in the full-length, recombinant human UG (rhUG) abrogates its sPLA2-inhibitory activity. We demonstrate further that recombinant UG does not bind Ca++ although when it is expressed with histidine-tag (H-tag) it is capable of binding Ca++. Taken together our results show that: (i) Lys 43 and Asp 46 in rhUG are critical residues for the sPLA2-inhibitory activity of UG and (ii) Ca++-sequestration by rhUG is not likely to be one of the mechanisms responsible for its sPLA2-inhibitory activity.

Aspartic Acid↗
PubMed2002

Transendothelial function of human metastatic melanoma cells: role of the microenvironment in cell-fate determination.

On the basis of the ability of aggressive melanoma cells to participate in vasculogenic mimicry, particularly their expression of endothelial-associated genes, we examined the plasticity of human metastatic cutaneous melanoma cells with respect to vascular function. Fluorescently labeled metastatic melanoma cells were challenged to an ischemic microenvironment surgically induced in the hind limbs of nude mice. The data reveal the capability of these melanoma cells to express cell-fate determination molecules, normally expressed during embryonic vasculogenesis, and to participate in the neovascularization of circulation-deficient muscle. These results demonstrate the powerful influence of the microenvironment on the transendothelial differentiation of aggressive melanoma cells, and may provide new perspectives on tumor cell plasticity that could be exploited for novel therapeutic strategies.

Animals↗