Luciane Pons Di Leone

Gastrin-Releasing Peptide Receptors Regulate Proliferation of C6 Glioma Cells through a Phosphatidylinositol 3-Kinase-Dependent Mechanism

Gastrin-releasing peptide (GRP) has been proposed as a major growth factor in brain tumors, and GRP receptor (GRPR) antagonists show antiproliferative effects in experimental gliomas. However, the underlying molecular events downstream of GRPR activation remain poorly understood. In the present study, we examined the role of the GRPR in regulating proliferation of glioma cells in vitro and its possible interaction with the phosphatidylinositol 3-kinase (PI3K) signaling pathway. Expression of GRPR mRNA and protein in C6, U-87MG, and U-373MG glioma cells was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Proliferation of C6 and U-87MG, but not U-373MG cells was significantly inhibited by the GRPR antagonist RC-3095, whereas the GRPR agonist bombesin (BB) significantly enhanced proliferation of C6 cells. The BB-induced stimulatory effect on cell proliferation was prevented by either RC-3095 or the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Our results provide the first evidence that the GRPR regulates proliferation of C6 glioma cells and suggest that PI3K is required for GRPR-mediated stimulation of glioma growth.

Clinical features in osteosarcoma and prognostic implications

OBJECTIVE To identify the clinical features in osteosarcoma and to investigate their influence on the prognosis of children and adolescents presenting this disease. MATERIAL AND METHODS The records of children and adolescents with osteosarcoma treated by the Bone Tumors Group of the state of Rio Grande do Sul, Brazil, between January 1992 and December 2001 were reviewed. RESULTS Fifty consecutive patients were included in this study. Mean age at diagnosis was 13 years (3-22); 68% of the patients were males. The primary site of disease was the femur in 50% of the patients, tibia in 30%, pelvis in 4%, humerus in 10%, fibula in 2% and other sites in 4%. Nineteen patients presented metastases at diagnosis (38%). All patients received chemotherapy and were treated with three different schemes. As for surgical treatment, 26 patients (52%) had an amputation and 17 (34%) received conservative surgery. Serum lactic dehydrogenase > 1,000 UI/ml (p = 0.0159, log rank), tumor necrosis < 90% and presence of metastases had a negative influence on prognosis. The overall 5-year survival was of 33.2+/-7.2% with mean follow-up of 36 months (6-126). Event-free survival was 29.7+/-7%. The 5-year event-free survival in non-metastatic patients was 45+/-10.7%, and zero in metastatic patients (follow-up of 78.4 and 18.7 months, respectively). Only two out of 19 metastatic patients are alive and free of disease at 18 and 30 months respectively. CONCLUSION Metastatic disease at diagnosis, serum levels of serum lactic dehydrogenase > 1,000 UI/ml and tumor necrosis < 90% are predictors of unfavorable prognosis. The excessively high incidence of metastatic patients may suggest the presence of an aggressive pattern of disease in our population, or may indicate late diagnosis.

Phase II trial and pharmacokinetic study of thalidomide in patients with metastatic colorectal cancer

Introduction. This study was designed to estimate the percentage of objective tumor responses, toxicity profile, and obtain additional information about the plasma pharmacokinetics of thalidomide in patients with refractory and progressing metastatic colorectal cancer. Study design. This phase II clinical trial was conducted according to the two-stage Simon method with the inclusion of consecutive patients. The study protocol was approved by the Institutional Review Board (IRB) of the Academic Hospital (HCPA) of the Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil. Patients and methods. Seventeen patients with previously treated, refractory progressive metastatic colorectal cancer were eligible. Six patients had prior radiotherapy. The patients had a median of one previous chemotherapy regimen. Patients were initially treated with 200 mg/day of thalidomide with an increase in dose by 200 mg/day every 2 weeks until a final daily dose of 800 mg/day was achieved. Patients were evaluated every 8 weeks for response by radiographic criteria. Plasma pharmacokinetics studies were performed in four patients at 200 mg level and in one patient at 600 mg during the first 24 h. Main outcome measures and results. A total of 17 patients were accrued, all of them being evaluable for toxicity and 14 for response. Thalidomide was well tolerated, with constipation, somnolence, dizziness, and dry mouth being the major toxicities. There were no objective response or stable disease. The median survival was 3.6 months. Single-agent thalidomide is a generally well-tolerated drug that showed no antitumor activity in patients with advanced pretreated metastatic colorectal cancer. Although thalidomide did not show antitumor activity in this patient population, future studies of this agent in patients at initial stages of the disease (when its antiangiogenic properties may be more relevant to disease progression) could be considered.

Oral health and dental anomalies in patients treated for leukemia in childhood and adolescence

This study was conducted to evaluate oral health and dental anomalies in children treated for acute lymphoblastic leukemia (ALL) and to compare results with those of a group of healthy children matched for sex and age.