Lorena Bonadiman

Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori, Meldola, Emilia-Romagna, Italy

Are you Lorena Bonadiman?

Claim your profile

Publications (6)50.65 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: BACKGROUND Gastrointestinal stromal tumors (GISTs) are noncomplex sarcomas that often are due to c-kit-activating and platelet-derived growth factor receptor α gene (PDGFRα)-activating mutations and perturbations of their related signaling pathways. Molecular and cytogenetic findings have indicated correlations between tumor progression and high-risk GISTs with c-kit mutations, the overexpression of genes such as ezrin, and losses at 9p. In particular, it was reported recently that malignant GISTs showed alterations in the p16INK4a gene located at the 9p21 locus.METHODS To assess the involvement of p14ARF and p15INK4b in addition to p16INK4a in GISTs, the authors undertook a molecular and cytogenetic study of the 9p21 locus. A series of 22 pre-Gleevec era, cryopreserved, high-risk GISTs that were characterized well in terms of KIT and PDGFRα receptors were investigated for mRNA expression, homozygous deletions, mutations, and promoter methylation of locus 9p21, in some instances complemented by fluorescent in situ hybridization studies.RESULTSThe results indicated the loss of p16INK4a mRNA expression in 41% of the GISTs, mainly due to the homozygous deletion of both the p16INK4a gene and the p14ARF gene (24%). No mutations were found, and promoter methylation (detected by means of methylation-specific polymerase chain reaction analysis in 27% of tumors) was restricted mainly to the p15INK4b gene (20%). It is noteworthy that, in all of the methylated GISTs, the epigenetic promoter alteration was coupled with mRNA expression.CONCLUSIONS Alterations in the 9p21 locus were found cumulatively in 54% of the tumors in the current series and were represented mainly by the loss of tumor suppressor gene expression. The p16INK4a deletion, which always was coupled with p14ARF gene loss, seemed to be the most common 9p21 inactivation mechanism. Cancer 2005. © 2005 American Cancer Society.
    Cancer 06/2005; 104(1):159 - 169. · 5.20 Impact Factor
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: The combinations of various chemotherapeutic drugs currently used to treat advanced small cell lung cancer (SCLC) led to similarly poor survival outcomes, which is why new molecular biology approaches are needed to design and select targeted therapies. Thirteen stage I SCLC surgical specimens were screened for c-Kit gene mutations by sequencing whole cDNA and for KIT receptor expression/activation by immunoprecipitation and Western blotting. Both the paraffin-embedded and frozen materials were analyzed by immunocytochemistry, and the stem cell factor cognate ligand was assessed by retrotranscription PCR. In all cases, we showed the presence of wild-type KIT receptors by analyzing the entire coding sequence, which together with the detection of the cognate ligand stem cell factor, supports the establishment of an autocrine loop. In addition, the KIT receptor was activated/phosphorylated. The immunoprecipitation/Western blotting data fit the observed immunophenotype. Interestingly, comparison of the level of KIT expression was at least 10 times higher in the tumoral specimens than the normal reference lungs. The KIT molecular profile derived from the analysis of SCLC surgical specimens shows that wild-type KIT is overexpressed and phosphorylated in the presence of stem cell factor. This finding, which is consistent with pathological KIT activation driven by an autocrine loop, is particularly interesting in the light of the recent development of new tyrosine kinase inhibitory drugs, which are highly effective in blocking wild-type KIT receptors.
    Clinical Cancer Research 01/2005; 10(24):8214-9. · 7.84 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Imatinib, a tyrosine kinase inhibitor of BCR-ABL, KIT, and platelet-derived growth factor receptor, is used in patients with chronic myelogenous leukemia (CML) and gastrointestinal stromal tumors (GIST). Primary and acquired resistance to the drug can occur in both diseases. Molecular mechanisms have been reported in CML and GIST for primary resistance, whereas extensive studies on the mechanisms responsible for secondary resistance have been almost exclusively reported for CML. In a patient with advanced GIST undergoing imatinib therapy, an isolated progressing peritoneal mass was excised, along with 2 still-responding lesions. Complementary DNA and genomic DNA were analyzed by sequencing for c-Kit gene mutations. KIT receptor expression and phosphorylation status were assessed by immunoprecipitation and Western blot. Transient-transfection experiments were performed with mutagenized KIT constructs, and their activation status was assessed. In addition to an exon 11 mutation, shared among all of the analyzed lesions, a novel point mutation in c-Kit exon 14 resulting in T670I substitution was found only in the progressing lesion, which harbored a phosphorylated receptor, as opposed to the finding of an inactive receptor in responding lesions. Functional analyses showed that KIT/T670I is insensitive to imatinib and that T670I mutation, introduced in a receptor responding to imatinib, subverted its sensitivity to the drug. This new mutation was confined to the progressing lesion; the resulting amino acidic substitution, T670I, affecting the ATP/imatinib pocket of KIT, makes it insensitive to the drug. Interestingly, this substitution is a homologue to the T315I mutation already reported in CML, where it is responsible for acquired resistance to imatinib.
    Gastroenterology 07/2004; 127(1):294-9. · 12.82 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: The use of tyrosine kinase receptor inhibitors is increasingly becoming a valuable therapeutic alternative in tumors carrying activated tyrosine kinase receptors. In a previous study, we described a coexpression of KIT and stem cell factor (SCF) mRNA in Synovial sarcomas, (SS) and in a limited number of cases, we demonstrated the presence of an activated receptor. Here, in a wider number of cases, we investigated the expression level and phosphorylation status of two structurally related tyrosine kinase receptors, KIT and platelet-derived growth factor receptor beta (PDGFRbeta), at the light of their role as possible targets of tyrosine kinase receptors inhibitor molecules. Forty-three SS cases were analyzed for KIT and PDGFRbeta expression/activation by immunoprecipitation/Western blotting experiments. The cognate ligands, SCF and PDGFB, were detected by reverse transcription-PCR. KIT was observed in 48 and 41% (45% total) whereas PDGFRbeta in 54 and 33% (45% total) of monophasic and biphasic SS cases, respectively. With respect to the fusion transcript type SYTSSX1 and SYTSSX2, KIT was more expressed in SYTSSX1 carrying cases (48 versus 38%), whereas PDGFRbeta resulted more frequently expressed in SYTSSX2 ones (54 versus 37%). When expressed, the receptors were phosphorylated. Their ligands were detected in all of the activated cases. About 70% of the cases express one of the two activated tyrosine kinase receptors with a mutually exclusive expression trend. Coexpression is not frequent and seems to be restricted to monophasic subtype. These data indicate that a consistent fraction of this tumor type could represent a good candidate for kinase inhibitor molecules effective on KIT and PDGFRbeta where their activation is sustained by an autocrine loop.
    Clinical Cancer Research 03/2004; 10(3):938-43. · 7.84 Impact Factor
  • Source
    CancerSpectrum Knowledge Environment 08/2003; 95(14):1087-8; author reply 1088-9. · 14.07 Impact Factor
  • American Journal of Clinical Pathology 10/2002; 118(3):472-3; author reply 473. · 2.88 Impact Factor