Biomedical subjects

Renata Piccoli

Publications and source records attributed to Renata Piccoli.

5 recordsLinked to original sources

PubMed2006

Recombinant amyloidogenic domain of ApoA-I: analysis of its fibrillogenic potential.

A variety of amyloid diseases are associated with fibrillar aggregates from N-terminal fragments of ApoA-I generated through a largely unexplored multi-step process. The understanding of the molecular mechanism is impaired by the lack of suitable amounts of the fibrillogenic polypeptides that could not be produced by recombinant methods so far. We report the production and the conformational analysis of recombinant ApoA-I 1-93 fragment. Similarly to the polypeptide isolated ex vivo, a pH switch from 7 to 4 induces a fast and reversible conformational transition to a helical state and leads to the identification of a key intermediate in the fibrillogenesis process. Limited proteolysis experiments suggested that the C-terminal region is involved in helix formation. The recombinant polypeptide generates fibrils at pH 4 on a time scale comparable with that of the native fragment. These findings open the way to studies on structural, thermodynamic, and kinetic aspects of ApoA-I fibrillogenesis.

Amyloid↗

PubMed2004

A fully human antitumor immunoRNase selective for ErbB-2-positive carcinomas.

We report the preparation and characterization of a novel, fully human antitumor immunoRNase (IR). The IR, a human RNase and fusion protein made up of a human single chain variable fragment (scFv), is directed to the ErbB-2 receptor and overexpressed in many carcinomas. The anti-ErbB-2 IR, named hERB-hRNase, retains the enzymatic activity of the wild-type enzyme (human pancreatic RNase) and specifically binds to ErbB-2-positive cells with the high affinity (K(d) = 4.5 nm) of the parental scFv. hERB-hRNase behaves as an immunoprotoxin and on internalization by target cells becomes selectively cytotoxic in a dose-dependent manner at nanomolar concentrations. Administered in five doses of 1.5 mg/kg to mice bearing an ErbB-2-positive tumor, hERB-hRNase induced a dramatic reduction in tumor volume. hERB-hRNase is the first fully human antitumor IR produced thus far, with a high potential as a poorly immunogenic human drug devoid of nonspecific toxicity, directed against ErbB-2-positive malignancies.

Amino Acid Sequence↗

PubMed2003

Antineoplastic ribonucleases selectively kill thyroid carcinoma cells via caspase-mediated induction of apoptosis.

Bovine seminal ribonuclease (BS-RNase), a natural dimeric homolog of bovine pancreatic RNase (RNase A), and HHP2-RNase, an engineered dimeric form of human pancreatic RNase (HP-RNase), are endowed with powerful antitumor effects. Here we show that BS- and HHP2-RNases, but not monomeric RNase A, induce apoptosis of human thyroid carcinoma cell lines. RNase-induced apoptosis was associated with activation of initiation caspase-8 and -9. This was followed by activation of executioner caspase-3, leading to the proteolytic cleavage of poly(ADP-ribose) polymerase. The caspase inhibitor Z-Val-Ala-Asp-(OMe)-fluoromethylketone protected thyroid cancer cells from BS-RNase-induced apoptosis. RNase-triggered apoptosis and caspase activation were accompanied by reduced phosphorylation of Akt/protein kinase B (PKB), a serine-threonine kinase that when phosphorylated is able to deliver survival signals to cancer cells. BS-RNase antitumor effects in nude mice were accompanied by caspase activation and apoptosis. Because of the high selectivity of apoptotic effects for malignant cells, BS- and HHP2-RNase are promising tools for the treatment of aggressive thyroid cancer.

Amino Acid Chloromethyl Ketones↗

PubMed2002

A new RNase-based immunoconjugate selectively cytotoxic for ErbB2-overexpressing cells.

We report a new tumor-directed immunoRNase, a chimeric protein made up of an antibody fragment (single-chain Fv fragment) directed to ErbB2, a cell surface receptor, and a non-toxic, human ribonuclease, which upon cell internalization becomes cytotoxic. The immunoRNase is active as a ribonuclease, specifically binds and selectively kills ErbB2-positive cells. ErbB2 is one of the most specific tumor-associated antigens identified so far, overexpressed on tumor cells of different origin. Its choice as target antigen and that of a non-toxic, human RNase as the killer moiety makes this immunoRNase a new, potentially attractive anticancer agent.

Antigens, Neoplasm↗

PubMed2002

A new human antitumor immunoreagent specific for ErbB2.

PURPOSE: Our aim was to isolate a novel human mini-antibody(scFv) that specifically targets ErbB2-positive cancer cells. ErbB2, a tyrosinekinase receptor, is overexpressed in clinically significant tumors, such as breast, ovary, and lung carcinomas. In normal tissues, it is expressed only in certain epithelial cell types. EXPERIMENTAL DESIGN: A large phagemid library (Griffin.1 library) of human scFv was used for the isolation of the ErbB2-specific scFv. A very effective strategy was developed for the isolation, consisting in a double subtractive selection, the use of two different combinations of "positive," i.e., ErbB2-bearing, and "negative" cell lines. RESULTS: Here we report the isolation of the first human anti-ErbB2 mini-antibody endowed with antitumor action. Both in its soluble and phage format, it binds specifically to ErbB2, inhibits its autophosphorylation, is internalized by target cells, and exerts a strong and specific antiproliferative action on ErbB2-positive target cells. A correlation was found between the extent of this antiproliferative effect and the expression levels of ErbB2 on target cells, with a strong cytotoxicity for hyper-expressing cells, such as SKBR3, in which apoptosis was evidenced. CONCLUSIONS: This scFv is a potentially effective immunoreagent for diagnostics and therapeutics of certain cancers, both as a readily diffused molecule in solid tumors and as an essential asset for the construction of fully human anticancer drugs.

Animals↗