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Retroperitoneal soft tissue sarcomas (RPS) are rare tumors. Surgery is the mainstay of curative therapy, but local recurrence is common. No recommendations concerning the best management of recurring disease have been developed so far. Although every effort should be made to optimize the initial approach, recommendations to treat recurring RPS will be helpful to maximize disease control at recurrence. An RPS transatlantic working group was established in 2013. The goals of the group were to share institutional experiences, build large multi-institutional case series, and develop consensus documents on the approach to this difficult disease. The outcome of this document applies to recurrent RPS that is nonvisceral in origin. Included are sarcomas of major veins, undifferentiated pleomorphic sarcoma of psoas, ureteric leiomyosarcoma (LMS). Excluded are desmoids-type fibromatosis, angiomyolipoma, gastrointestinal stromal tumors, sarcomas arising from the gut or its mesentery, uterine LMS, prostatic sarcoma, paratesticular/spermatic cord sarcoma, Ewing sarcoma, alveolar/embryonal rhabdomyosarcoma, sarcoma arising from teratoma, carcinosarcoma, sarcomatoid carcinoma, clear cell sarcoma, radiation-induced sarcoma, paraganglioma, and malignant pheochromocytoma. Recurrent RPS management was evaluated from diagnosis to follow-up. It is a rare and complex malignancy that is best managed by an experienced multidisciplinary team in a specialized referral center. The best chance of cure is at the time of primary presentation, but some patients may experience prolonged disease control also at recurrence, when the approach is optimized and follows the recommendations contained herein. International collaboration is critical for adding to the present knowledge. A transatlantic prospective registry has been established.

Sixty human brain tumors, classified according to the New World Health Organization (WHO) classification including, grade I schwannomas, meningiomas and pilocytic astrocytomas, grade II astrocytomas, grade III anaplastic astrocytomas, grade IV glioblastomas, grade III anaplastic oligodendrogliomas and grade IV glioblastomas and lung and melanoma metastases were analyzed for the expression of three matrix metalloproteinases (MMPs), two tissue inhibitors of MMPs (TIMPs) and for MMP activity. Some correlation was found between MMP expression and the degree of malignancy. Western blotting analysis revealed a more uniform pattern of distribution of MMP-2 (gelatinase A) than of MMP-9 (gelatinase B) and MMP-12 (metalloelastase) among tumors. MMP-9 levels were found to be significantly higher in grade III anaplastic astrocytomas and anaplastic oligodendrogliomas than those in grade I schwannomas and meningiomas. Anaplastic astrocytomas and Grade IV glioblastomas expressed significantly higher levels MMP-12 than grade I meningiomas. All sixty tumors showed a similar pattern of activity in zymography, proMMP-9 being the major species detected. Interestingly, TIMP-1 and TIMP-2 expression levels were especially low in tumors of grade II and grade III but significantly higher in tumors of grade I, particularly in schwannomas. Taken together, these data suggest that: 1) a balance between MMPs and TIMPs has an important role to play in human brain tumors; 2) TIMP expression may be valuable markers for tumor malignancy.

Publisher Summary Free-radical reactions have been implicated in a wide variety of diseases, including inflammation, irradiation-induced injury, and ischemia. The role played by superoxide anion radical (O 2 - ) in these conditions is being elucidated using a number of model systems. This chapter provides an approach to the understanding of the systemic consequences of O 2 - generation. A valuable conceptual model has been to categorize disease states by the major site of pathological O 2 - generation. Increased free-radical generation may occur predominantly intracellularly, extracellularly, and both intracellularly and extracellularly. Decreased O 2 - generation may occur intracellularly and extracellularly. The consequences of the systemic generation of O 2 - clearly present a challenge to those concerned with biological phenomena. The study and interpretation of O 2 - interactions is fraught with difficulties. However, only through a more complete understanding of this complicated and reactive species its role in disease processes can be assessed.

Twist1 promote the bypass of p53 response by interacting with p53 and facilitating its MDM2-mediated degradation. We reasoned that reagents able to interfere with the p53:Twist1 complex might alleviate Twist1 inhibitory effect over p53, thus representing potential therapeutic tools in p53 wild type tumors. From a pre-immune library of llama nanobodies (VHH), we isolated binders targeting the p53 C-terminal region (p53-CTD) involved in the interaction with Twist1 by using recombinant Twist1 as an epitope-specific competitor during elution. Positive hits were validated by proving their capacity to immunoprecipitate p53 and to inhibit Twist1:p53 binding in vitro. Molecular modeling confirmed a preferential docking of positive hits with p53-CTD. D11 VHH activity was validated in human cell models, succeeded in immunoprecipitating endogenous p53 and, similarly to Twist1 knock-down, interfered with p53 turnover, p53 phosphorylation at Serine 392 and affected cell viability. Despite the limited functional effect determined by D11 expression in target cells, our results provide the proof of principle that nanobodies ectopically expressed within a cell, have the capacity to target the assembly of the pro-tumorigenic Twist1:p53 complex. These results disclose novel tools for dissecting p53 biology and lay down the grounds for the development of innovative targeted therapeutic approaches.

SMARCB1 inactivation is a well-established trigger event in atypical teratoid/rhabdoid tumor. Recently, a role for SMARCB1 inactivation has emerged as a mechanism of clonal evolution in other tumor types, including rare brain tumors. We describe an unusual malignant intra-axial SMARCB1-deficient spindle cell desmoplastic neoplasm, occurring in a 6-year-old child with meningioangiomatosis and a long history of seizures. Striking features of the tumor were a storiform pattern and strong CD34 expression. Undifferentiated round cell areas with isolated rhabdoid cells showing high mitotic index and focal necrosis with INI1 expression loss were present. The meningioangiomatosis component showed few chromosomal imbalances, including chromosomal 22 monosomy (where SMARCB1 maps) and gain at 6q14.3. In addition to these abnormalities, the spindle cell desmoplastic neoplasm and its dedifferentiated SMARCB1-deficient component shared several other aberrations, including homozygous deletion at 9p21.3, losses at 1p, 3p, 3q, 10p, and 13q, gains and losses at 5p and 11p. In line with INI1 loss, the dedifferentiated component showed remarkably decreased levels of SMARCB1 transcript. The residual SMARCB1 allele was wildtype. Our findings suggest progression from the meningioangiomatosis to the malignant desmoplastic neoplasm through the occurrence of complex chromosomal abnormalities, and point to functional silencing of SMARCB1 in the dedifferentiation component.

Inactivation of p53 contributes significantly to the dismal prognosis of breast tumors, most notably triple-negative breast cancers (TNBCs). How the relief from p53 tumor suppressive functions results in tumor cell aggressive behavior is only partially elucidated. In an attempt to shed light on the implication of microRNAs in this context, we discovered a new signaling axis involving p53, miR-30a and ZEB2. By an in silico approach we identified miR-30a as a putative p53 target and observed that in breast tumors reduced miR-30a expression correlated with p53 inactivation, lymph node positivity and poor prognosis. We demonstrate that p53 binds the MIR30A promoter and induces the transcription of both miRNA strands 5p and 3p. Both miR-30a-5p and -3p showed the capacity of targeting ZEB2, a transcription factor involved in epithelial-mesenchymal transition (EMT), tumor cell migration and drug resistance. Intriguingly, we found that p53 does restrain ZEB2 expression via miR-30a. Finally, we provide evidence that the new p53/miR-30a/ZEB2 axis controls tumor cell invasion and distal spreading and impinges upon miR-200c expression. Overall, this study highlights the existence of a novel axis linking p53 to EMT via miR-30a, and adds support to the notion that miRNAs represent key elements of the complex network whereby p53 inactivation affects TNBC clinical behavior.

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors of the gastrointestinal tract, are characterized by activating mutations in KIT or PDGFRA genes. The vast majority of GISTs are sporadic, but rare hereditary forms have been reported, often featuring multifocality and younger age of onset. We here report the identification of a novel kindred affected by familial GIST caused by a KIT germline mutation in exon 13 (N655K). No family affected by hereditary GIST due to this KIT variant has been reported in literature so far. We were able to track the mutation in three members of the family (proband, mother, and second-degree cousin), all affected by multiple GISTs. Due to its rarity, the N655K variant is poorly characterized. We conducted in vitro drug sensitivity assays that indicated that most tyrosine kinase inhibitors (TKIs) currently included in the therapeutic armamentarium for GISTs have a limited inhibitory activity toward this mutation. However, when compared to a classical imatinib-resistant KIT mutation (T670I), N655K was slightly more sensitive to imatinib, and encouraging responses were observed with last-generation TKIs.

[Background] Extraskeletal myxoid chondrosarcoma is a rare sarcoma with low sensitivity to cytotoxic chemotherapy. Retrospective evidence suggests that antiangiogenic drugs could be a treatment option. We aimed to investigate the activity of pazopanib, an antiangiogenic drug, in patients with advanced extraskeletal myxoid chondrosarcoma., [Methods] In this single-arm, open-label phase 2 trial, three parallel independent cohorts of different histotypes of advanced sarcomas were recruited (extraskeletal myxoid chondrosarcoma, typical solitary fibrous tumour, and malignant-dedifferentiated solitary fibrous tumour). In each cohort, patients received pazopanib. In this Article, we report the results of the cohort of patients with advanced extraskeletal myxoid chondrosarcoma. Separate reporting of the three cohorts was prespecified in the study protocol. In this cohort, adult patients (aged ≥18 years) with a diagnosis of NR4A3-translocated, metastatic, or unresectable extraskeletal myxoid chondrosarcoma, who had Response Evaluation Criteria in Solid Tumors (RECIST) progression in the previous 6 months, and had an Eastern Cooperative Oncology Group performance status of 0–2, were enrolled at 11 study sites of the Spanish, Italian, and French sarcoma groups. Patients received oral pazopanib (800 mg/day) continuously, until disease progression, unacceptable toxicity, death, non-compliance, patient refusal, or investigator's decision. The primary endpoint was the proportion of patients achieving an objective response according to RECIST 1·1 in the modified intention-to-treat population (patients who provided consent and had a central molecularly confirmed diagnosis of extraskeletal myxoid chondrosarcoma). The safety analysis included all patients who received at least one dose of pazopanib. This study is registered with ClinicalTrials.gov, number NCT02066285., [Findings] Between June 24, 2014, and Jan 17, 2017, 26 patients entered the study and started pazopanib. Of these, 23 met the eligibility criteria for the modified intention-to-treat analysis. Median follow-up was 27 months (IQR 18–30). 22 patients (one patient died before the primary analysis) were evaluable for the primary endpoint: four (18% [95% CI 1–36]) had a RECIST objective response. No deaths or grade 4 adverse events occurred. The most frequent grade 3 adverse events were hypertension (nine [35%] of 26 patients), increased concentration of alanine aminotransferase (six [23%]), and increased aspartate aminotransferase (five [19%])., [Interpretation] Pazopanib had clinically meaningful antitumour activity in patients with progressive and advanced extraskeletal myxoid chondrosarcoma, and could be considered a suitable option after failure to respond to first-line anthracycline-based chemotherapy in these patients., Funding: Spanish Group for Research on Sarcomas, Italian Sarcoma Group, French Sarcoma Group, GlaxoSmithKline, and Novartis.

Dermatofibrosarcoma protuberans (DFSP) is a rare and indolent cutaneous sarcoma. At times, a fibrosarcomatous transformation marked by a more aggressive clinical behavior may be present. We investigated the natural history and the molecular bases of progression from classic DFSP to the fibrosarcomatous form (FS-DFSP), looking, retrospectively, at the outcome of all patients affected by primary DFSP treated at our institution from 1993 to 2012 and analyzing the molecular profile of 5 DFSPs and 5 FS-DFSPs by an integrated genomics approach (whole transcriptome sequencing, copy number analysis, FISH, qRT-PCR, IHC). The presence of fibrosarcomatous features was identified in 20 (7.6%) patients out of 263 DFSP. All cases were treated with macroscopic complete surgery. A local relapse occurred in 4 of 23 patients who received a microscopic marginal surgery (2 classic DFSP, 2 FS-DFSP), while metastasis affected 2 patients, both FS-DFSP (10% of FS-DFSP), being the first event. DFSP evolution to FS-DFSP was paralleled by a transcriptional reprogramming. The recurrent loss of chromosome 22q appeared to contribute to this phenomenon by promoting the expression of epigenetic regulators, such as EZH2. Loss of the p16/CDKN2A/INK4A locus at 9p was also observed in two FS-DFSP metastatic cases. Implications: FS-DFSP is a rare subgroup among DFSP, with a 10% metastatic risk, that was independent from local recurrence and that was not observed in DFSP, that were all cured by wide surgery. Chromosome 22q deletion might play a role in FS-DFSP, and p16 loss may convey a poor outcome. EZH2 dysregulation was also found and represents a druggable target. Mol Cancer Res; 14(9); 820–9. ©2016 AACR.

Background Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma, marked by NR4A3 rearrangement. Herein we report on the activity of sunitinib in a series of 10 patients, strengthening what initially observed in two cases. Patients and methods From July 2011, 10 patients with progressive metastatic translocated EMC have been consecutively treated with sunitinib 37.5 mg/day, on a named-use basis. In an attempt to interpret the activity of sunitinib in EMC, genotype/phenotype correlations were carried out by fluorescence in situ hybridization (FISH) analyses. Moreover, transcriptome, immunohistochemical and biochemical analyses of a limited set of samples were performed focusing on some putative targets of sunitinib. Results Eight of 10 patients are still on therapy. Six patients had a Response Evaluation Criteria in Solid Tumours (RECIST) partial response (PR), two were stable, two progressed. Positron emission tomography (PET) was consistent in 6/6 evaluable cases. One patient underwent surgery after sunitinib, with evidence of a pathologic response. At a median follow-up of 8.5 months (range 2–28), no secondary resistance was detected. Median progression free survival (PFS) has not been reached. Interestingly, all responsive cases turned out to express the typical EWSR1–NR4A3 fusion, while refractory cases carried the alternative TAF15–NR4A3 fusion. Among putative sunitinib targets, only RET was expressed and activated in analysed samples. Conclusions This report confirms the therapeutic activity of sunitinib in EMC. Genotype/phenotype analyses support a correlation between response and EWSR1–NR4A3 fusion. Involvement of RET deserves further investigation.

// James A. McCubrey 1 , Linda S. Steelman 1 , Fred E. Bertrand 2 , Nicole M. Davis 1 , Melissa Sokolosky 1 , Steve L. Abrams 1 , Giuseppe Montalto 3 , Antonino B. D’Assoro 4 , Massimo Libra 5 , Ferdinando Nicoletti 5 , Roberta Maestro 6 , Jorg Basecke 7,8 , Dariusz Rakus 9 , Agnieszka Gizak 9 Zoya Demidenko 10 , Lucio Cocco 11 , Alberto M. Martelli 11 and Melchiorre Cervello 12 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University Greenville, NC, USA 2 Department of Oncology, Brody School of Medicine at East Carolina University Greenville, NC, USA 3 Biomedical Department of Internal Medicine and Specialties, University of Palermo, Palermo, Italy 4 Department of Medical Oncology, Mayo Clinic Cancer Center, Rochester, MN, USA 5 Department of Bio-Medical Sciences, University of Catania, Catania, Italy 6 Experimental Oncology 1, CRO IRCCS, National Cancer Institute, Aviano, Pordenone, Italy. 7 Department of Medicine, University of Gottingen, Gottingen, Germany 8 Sanct-Josef-Hospital Cloppenburg, Department of Hematology and Oncology, Cloppenburg, Germany 9 Department of Animal Molecular Physiology, Institute of Experimental Biology, Wroclaw University, Wroclaw, Poland 10 Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY, USA 11 Dipartimento di Scienze Biomediche e Neuromotorie, Universita di Bologna, Bologna, Italy 12 Consiglio Nazionale delle Ricerche, Istituto di Biomedicina e Immunologia Molecolare “Alberto Monroy”, Palermo, Italy Correspondence: James A. McCubrey, email: // Keywords : GSK-3, cancer stem cells, Wnt/beta-catenin, PI3K, Akt, mTOR, Hedgehog, Notch, Targeted Therapy, Therapy Resistance, Mutations, Rapamycin Received : April 24, 2014 Accepted : May 28, 2014 Published : May 28, 2014 Abstract The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) was initially identified and studied in the regulation of glycogen synthesis. GSK-3 functions in a wide range of cellular processes. Aberrant activity of GSK-3 has been implicated in many human pathologies including: bipolar depression, Alzheimer’s disease, Parkinson’s disease, cancer, non-insulin-dependent diabetes mellitus (NIDDM) and others. In some cases, suppression of GSK-3 activity by phosphorylation by Akt and other kinases has been associated with cancer progression. In these cases, GSK-3 has tumor suppressor functions. In other cases, GSK-3 has been associated with tumor progression by stabilizing components of the beta-catenin complex. In these situations, GSK-3 has oncogenic properties. While many inhibitors to GSK-3 have been developed, their use remains controversial because of the ambiguous role of GSK-3 in cancer development. In this review, we will focus on the diverse roles that GSK-3 plays in various human cancers, in particular in solid tumors. Recently, GSK-3 has also been implicated in the generation of cancer stem cells in various cell types. We will also discuss how this pivotal kinase interacts with multiple signaling pathways such as: PI3K/PTEN/Akt/mTORC1, Ras/Raf/MEK/ERK, Wnt/beta-catenin, Hedgehog, Notch and others.

// Nicole M. Davis 1 , Melissa Sokolosky 1 , Kristin Stadelman 1 , Stephen L. Abrams 1 , Massimo Libra 2 , Saverio Candido 2 , Ferdinando Nicoletti 2 , Jerry Polesel 3 , Roberta Maestro 4 , Antonino D’Assoro 5 , Lyudmyla Drobot 6 , Dariusz Rakus 7 , Agnieszka Gizak 7 , Piotr Laidler 8 , Joanna Dulinska-Litewka 8 , Joerg Basecke 9 , Sanja Mijatovic 10 , Danijela Maksimovic-Ivanic 10 , Giuseppe Montalto 11,12 , Melchiorre Cervello 12 , Timothy L. Fitzgerald 13 , Zoya N. Demidenko 14 , Alberto M. Martelli 15 , Lucio Cocco 15 , Linda S. Steelman 1 and James A. McCubrey 1 1 Department of Microbiology and Immunology, Brody School of Medicine at East Carolina University Greenville, NC 27858 USA 2 Department of Bio-Medical Sciences, University of Catania, Catania, Italy 3 Unit of Epidemiology and Biostatistics, Centro di Riferimento Oncologico, IRCCS, Aviano, Italy 4 Experimental Oncology 1, CRO IRCCS, National Cancer Institute, Aviano, Pordenone, Italy 5 Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN, USA 6 Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine 7 Department of Animal Molecular Physiology, Institute of Experimental Biology, Wroclaw University, Wroclaw, Poland 8 Chair of Medical Biochemistry, Jagiellonian University Medical College, Krakow, Poland 9 Department of Medicine University of Gottingen, Gottingen, Germany 10 Department of Immunology, Institute for Biological Research “Sinisa Stankovic” University of Belgrade, Belgrade, Serbia 11 Biomedical Department of Internal Medicine and Specialties, University of Palermo, Palermo, Italy 12 Consiglio Nazionale delle Ricerche,Istituto di Biomedicina e Immunologia Molecolare “Alberto Monroy”, Palermo, Italy 13 Department of Surgery, Brody School of Medicine at East Carolina University, Greenville, NC 14 Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY, USA 15 Dipartimento di Scienze Biomediche e Neuromotorie, Universita di Bologna, Bologna, Italy Correspondence: James A. McCubrey, email: // Keywords : Targeted Therapy, Therapy Resistance, Mutations, PI3K, mTOR, rapamycin Received : June 04, 2014 Accepted : July 11, 2014 Published : July 12, 2014 Abstract The EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway plays prominent roles in malignant transformation, prevention of apoptosis, drug resistance and metastasis. The expression of this pathway is frequently altered in breast cancer due to mutations at or aberrant expression of: HER2 , ER alpha, BRCA1, BRCA2, EGFR1 , PIK3CA , PTEN , TP53 , RB as well as other oncogenes and tumor suppressor genes. In some breast cancer cases, mutations at certain components of this pathway ( e.g. , PIK3CA ) are associated with a better prognosis than breast cancers lacking these mutations. The expression of this pathway and upstream HER2 has been associated with breast cancer initiating cells (CICs) and in some cases resistance to treatment. The anti-diabetes drug metformin can suppress the growth of breast CICs and herceptin-resistant HER2+ cells. This review will discuss the importance of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway primarily in breast cancer but will also include relevant examples from other cancer types. The targeting of this pathway will be discussed as well as clinical trials with novel small molecule inhibitors. The targeting of the hormone receptor, HER2 and EGFR1 in breast cancer will be reviewed in association with suppression of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway.

Twist proteins have been shown to contribute to cancer development and progression by impinging on different regulatory pathways, but their mechanism of action is poorly defined. By investigating the role of Twist in sarcomas, we found that Twist1 acts as a mechanism alternative to TP53 mutation and MDM2 overexpression to inactivate p53 in mesenchymal tumors. We provide evidence that Twist1 binds p53 C terminus through the Twist box. This interaction hinders key posttranslational modifications of p53 and facilitates its MDM2-mediated degradation. Our study suggests the existence of a Twist box code of p53 inactivation and provides the proof of principle that targeting the Twist box:p53 interaction might offer additional avenues for cancer treatment. Twist proteins have been shown to contribute to cancer development and progression by impinging on different regulatory pathways, but their mechanism of action is poorly defined. By investigating the role of Twist in sarcomas, we found that Twist1 acts as a mechanism alternative to TP53 mutation and MDM2 overexpression to inactivate p53 in mesenchymal tumors. We provide evidence that Twist1 binds p53 C terminus through the Twist box. This interaction hinders key posttranslational modifications of p53 and facilitates its MDM2-mediated degradation. Our study suggests the existence of a Twist box code of p53 inactivation and provides the proof of principle that targeting the Twist box:p53 interaction might offer additional avenues for cancer treatment.

10 páginas, 5 figuras, 1 tabla.-- et al., [Context]:Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human tumors; it is characterized by chemoresistance, local invasion, and distant metastases. ATC is invariably fatal. [Objective]:The aim was to study the role of TWIST1, a basic helix-loop-helix transcription factor, in ATC. [Design]:Expression of TWIST1 was studied by immunohistochemistry and real-time PCR in normal thyroids and well-differentiated, poorly differentiated, and ATC. The function of TWIST1 was studied by RNA interference in ATC cells and by ectopic expression in well-differentiated thyroid carcinoma cells. [Results]:ATCs up-regulate TWIST1 with respect to normal thyroids as well as to poorly and well-differentiated thyroid carcinomas. Knockdown of TWIST1 by RNA interference in ATC cells reduced cell migration and invasion and increased sensitivity to apoptosis. The ectopic expression of TWIST1 in thyroid cells induced resistance to apoptosis and increased cell migration and invasion. [Conclusions]:TWIST1 plays a key role in determining malignant features of the anaplastic phenotype in vitro., This work was supported by the Associazione Italiana per la Ricerca sul Cancro, the Istituto Superiore di Oncologia, the Italian Ministero della Salute, the Ministero dell’Università e della Ricerca, the European Community Contract FP6-36495, and the Programa Ramón y Cajal–Ministerio de Ciencia e Innovación, Social EU Funds, Universidad de Valladolid, Spain.

Purpose: Gastrointestinal stromal tumors (GIST) are commonly regarded as solitary tumors.The occurrence of multiple lesions is considered an extraordinary event restricted to pediatric GISTs and rare hereditary conditions.Beyond these well-defined situations, the presentation of multiple synchronous lesions is commonly viewed as the result of the metastatic spreading of a single primary GIST.Based on this axiom, patients with multifocal disease are classified as advanced stage and treated as such.Whether, indeed, the detection of several lesions in sporadic adult GIST patients may be suggestive of phenomena of tumor multiplicity still needs to be clarified. Experimental Design: From a multicentric series of 442 consecutive cases, 26 of which with advanced disease, we selected 5 patients who presented up to three distinct GIST nodules.Five additional cases with similar characteristics were also contributed by two other institutions.The clonal relationship between the synchronous lesions was assessed by comparing KIT/PDGFRA mutation and microsatellite pattern. Results: An independent origin of the synchronous lesions was established in 6 of 10 cases. Notably, in one patient, one lesion arose in the peritoneum, which is ordinarily regarded as a site of metastasis. Conclusions: Our data indicate that a significant fraction of GIST patients with multifocal pre- sentation are actually affected by multiple primary tumors, suggesting that mesenchymal GIST precursor cells of these individuals are somehow primed to transformation.Thus, in the presence of multifocal GIST manifestations, an accurate characterization of the different tumor sites should be undertaken for a proper patient staging and therapy planning. Gastrointestinal stromal tumors (GIST) are mesenchymal tumors most often originating in the muscular wall of the gastrointestinal tract. The estimated annual incidence is 12 to 14 per million, as recently reported in two European studies (1, 2). Stomach and small intestine are the most commonly affected anatomic sites, accounting for about two thirds and one third of the cases, respectively (3 - 5). Rare cases of primary GISTs originating outside the gastrointestinal tract have also been reported, although the actual existence of extragastro- intestinal GISTs is still debated (4, 6 - 9).

Oncogene activation increases susceptibility to apoptosis. Thus, tumorigenesis must depend, in part, on compensating mutations that protect from programmed cell death. A functional screen for cDNAs that could counteract the proapoptotic effects of the myc oncogene identified two related bHLH family members, Twist and Dermo1. Both of these proteins inhibited oncogene- and p53-dependent cell death. Twist expression bypassed p53-induced growth arrest. These effects correlated with an ability of Twist to interfere with activation of a p53-dependent reporter and to impair induction of p53 target genes in response to DNA damage. An underlying explanation for this observation may be provided by the ability of Twist to reduce expression of the ARF tumor suppressor. Thus, Twist may affect p53 indirectly through modulation of the ARF/MDM2/p53 pathway. Consistent with a role as a potential oncoprotein, Twist expression promoted colony formation of E1A/ras-transformed mouse embryo fibroblasts (MEFs) in soft agar. Furthermore, Twist was inappropriately expressed in 50% of rhabdomyosarcomas, a tumor that arises from skeletal muscle precursors that fail to differentiate. Twist is known to block myogenic differentiation. Thus, Twist may play multiple roles in the formation of rhabdomyosarcomas, halting terminal differentiation, inhibiting apoptosis, and interfering with the p53 tumor-suppressor pathway.