RESUMO
The mammalian target of rapamycin (mTOR) is a central controller of cell growth and is currently being investigated as a potential target in breast cancer therapy. The essential amino acid leucine has been proposed to regulate mTOR signaling. The objective of this study was to determine whether leucine restriction would inhibit mTOR signaling in breast cancer cells. Leucine restriction did not decrease mTOR signaling in any of the 8 breast cancer cell lines tested. In addition, in vivo administration of a leucine-free diet for up to 4 days did not result in a decrease in phosphorylation of mTOR target proteins in breast cancer xenografts. Further, in 3 different cell lines, an increase in Akt phosphorylation was observed after leucine restriction. This was observed without a decrease in S6K phosphorylation, suggesting a mechanism different from the feedback loop activation of Akt observed with rapamycin treatment. We conclude that leucine restriction is not sufficient to inhibit mTOR signaling in most breast cancer cell lines but is associated with activation of survival molecule Akt, making leucine deprivation an undesirable approach for breast cancer therapy.
Assuntos
Leucina/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Animais , Western Blotting , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Camundongos NusRESUMO
BACKGROUND: Breast cancer patients who are resistant to neoadjuvant chemotherapy (NeoCT) have a poor prognosis. There is a pressing need to develop in vivo models of chemo resistant tumors to test novel therapeutics. We hypothesized that patient-derived breast cancer xenografts (BCXs) from chemo- naïve and chemotherapy-exposed tumors can provide high fidelity in vivo models for chemoresistant breast cancers. METHODS: Patient tumors and BCXs were characterized with short tandem repeat DNA fingerprinting, reverse phase protein arrays, molecular inversion probe arrays, and next generation sequencing. RESULTS: Forty-eight breast cancers (24 post-chemotherapy, 24 chemo-naïve) were implanted and 13 BCXs were established (27%). BCX engraftment was higher in TNBC compared to hormone-receptor positive cancer (53.8% vs. 15.6%, p = 0.02), in tumors from patients who received NeoCT (41.7% vs. 8.3%, p = 0.02), and in patients who had progressive disease on NeoCT (85.7% vs. 29.4%, p = 0.02). Twelve patients developed metastases after surgery; in five, BCXs developed before distant relapse. Patients whose tumors developed BCXs had a lower recurrence-free survival (p = 0.015) and overall survival (p<0.001). Genomic losses and gains could be detected in the BCX, and three models demonstrated a transformation to induce mouse tumors. However, overall, somatic mutation profiles including potential drivers were maintained upon implantation and serial passaging. One BCX model was cultured in vitro and re-implanted, maintaining its genomic profile. CONCLUSIONS: BCXs can be established from clinically aggressive breast cancers, especially in TNBC patients with poor response to NeoCT. Future studies will determine the potential of in vivo models for identification of genotype-phenotype correlations and individualization of treatment.
Assuntos
Neoplasias da Mama/patologia , Resistencia a Medicamentos Antineoplásicos/fisiologia , Xenoenxertos/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Quimioterapia Adjuvante/métodos , Intervalo Livre de Doença , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Pessoa de Meia-Idade , Terapia Neoadjuvante/métodos , Recidiva Local de Neoplasia/patologia , Receptor ErbB-2/metabolismo , Receptores de Estrogênio/metabolismoAssuntos
Anestesia/efeitos adversos , Comitês de Cuidado Animal , Técnicos em Manejo de Animais/educação , Competência Clínica/normas , Ciência dos Animais de Laboratório/educação , Anestésicos Inalatórios/efeitos adversos , Bem-Estar do Animal , Animais , Injeções Intravenosas/efeitos adversos , Isoflurano/efeitos adversos , Ciência dos Animais de Laboratório/métodos , Ciência dos Animais de Laboratório/normas , Camundongos , Dor/prevenção & controleAssuntos
Adenocarcinoma/diagnóstico , Regulação Neoplásica da Expressão Gênica , Neoplasias Mamárias Animais/diagnóstico , Receptores do Fator de Necrose Tumoral/genética , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Animais , Antígenos Transformantes de Poliomavirus/metabolismo , Biomarcadores Tumorais/metabolismo , Modelos Animais de Doenças , Evolução Fatal , Feminino , Imuno-Histoquímica , Neoplasias Mamárias Animais/genética , Neoplasias Mamárias Animais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Receptores do Fator de Necrose Tumoral/metabolismo , Membro 25 de Receptores de Fatores de Necrose TumoralRESUMO
Daily vacuuming of floors and flat-shelf racks is a standard procedure in our rodent housing rooms. To determine whether the noise produced by this activity is a potential stressor to animals used for transgenic and knockout mouse production, we measured the sound levels in our genetically engineered mouse facility under ambient conditions and at the in-cage and room levels during vacuuming. Spectral analysis showed that vacuuming produces a multitonal, low-frequency noise that is not attenuated by microisolation caging with bedding material. Comparison of cage-level spectral analysis results with age-specific audiograms of C57Bl/6 and CD1 mice showed that vacuuming produces frequencies audible to C57Bl/6 mice at 3 and 6 mo of age and to CD1 mice at 1 mo of age. These findings suggest that vacuuming in animal rooms could be a source of stress to animals with these genetic backgrounds.