RESUMO
Although some evidence has been documented on EGFR/PI3K mediation of Akt activation in breast cancers, ILK and DNA-PK have not been investigated so far. The aim of this study was to analyze the expression of phosphorylated Akt (pAkt) in breast cancer, with respect to its upstream regulators. The immunostaining of pAkt (Ser473) in 70 invasive breast cancers revealed that status of CerbB2 could play a major role in Akt phosphorylation, while ILK was also involved in the stimulated level of pAkt. The results would provide an important clue for the activation of Akt and potential targeted therapy in breast cancer.
Assuntos
Neoplasias da Mama/metabolismo , Carcinoma Ductal de Mama/metabolismo , Carcinoma Intraductal não Infiltrante/metabolismo , Regulação Neoplásica da Expressão Gênica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor ErbB-2/metabolismo , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/genética , Carcinoma Ductal de Mama/patologia , Carcinoma Intraductal não Infiltrante/genética , Carcinoma Intraductal não Infiltrante/patologia , Proteína Quinase Ativada por DNA/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Proteínas Nucleares/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Receptor ErbB-2/genética , Estudos Retrospectivos , Transdução de Sinais/fisiologiaRESUMO
In a previous study, we demonstrated that telomerase transcriptional elements-interacting factor (TEIF) could up-regulate the expression of telomerase and DNA polymerase beta, increasing resistance to genotoxic agents. Here, we further report that TEIF can be stimulated by DNA damage and we have identified a cluster of repeated polypyrimidine tracts in the promoter of TEIF, which mediate both its basal transcription and its response to genotoxic agents. These polypyrimidine tracts are arranged in three types of repeating units and in each of these units there are 14 bp length tandem sequences, which are repeated three times. These sequences are also characteristically separated by an 11 bp interval sequence. Among these units, one type (5'-CCCCCCCATCCCCG-3') has been found to be involved in the transcriptional regulation of TEIF. At the same time, PTB1 (polypyrimidine tract-binding protein 1) has been shown to repress TEIF expression through interaction with this element. Up-regulation of TEIF may be achieved by PTB1 suppression that is induced by DNA damage, or by an olignucleotide decoy, which mediates reversal of suppression. This study provides new insight into the mechanism through which TEIF is involved in DNA damage response, together with insight into the role of polypyrimidine tracts in transcription regulation.
Assuntos
Regulação da Expressão Gênica , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Transcrição Gênica , Proteínas Adaptadoras de Transporte Vesicular , Sequência de Bases , Células Cultivadas , Dano ao DNA , Proteínas de Ligação a DNA , Células HeLa , Humanos , Microscopia de Fluorescência , Dados de Sequência Molecular , Proteína de Ligação a Regiões Ricas em Polipirimidinas/genética , Proteína de Ligação a Regiões Ricas em Polipirimidinas/metabolismo , Pirimidinas/análise , Fatores de Transcrição/análise , Fatores de Transcrição/metabolismo , Sítio de Iniciação de Transcrição , TransfecçãoRESUMO
OBJECTIVE: To explore the significance in the change of telomere length in mesenchymal sarcomas, through analyzing telomere length and expression of its associated proteins, including TRF1, POT1, hTERT, P53 and c-myc. METHODS: The telomere length in 20 cases of osteosarcomas, 25 of chondrosarcomas, 19 of rhabdomyosarcomas, 26 of liposarcomas was measured by telomere fluorescence in situ hybridization (Telo-FISH), and the expression of TRF1, POT1, hTERT, p53 or c-myc was analyzed by immunohistochemistry, respectively. RESULTS: The telomere length in osteosarcomas was significantly shorter than that of either chondrosarcomas or liposarcomas (P<0.05). Similarly, the telomere length of rhabdomyosarcoma was shorter than that of chondrosarcoma (P<0.05). Meanwhile, telomere shortening was positively correlated with down expression of telomere binding proteins TRF1 and POT1 (P<0.05), but trends were detected more frequently in positive expression of hTERT (P<0.05) and in nuclear accumulation of P53 or expression of c-myc. With advancing in histological grading, telomere length was shortened markedly in chondrosarcomas, especially in liposarcomas (P<0.05). CONCLUSION: The shortening of telomere could prevail in mesenchymal sarcoma and reflect the malignant potential. Telomere attrition usually correlated with down expression of POT1, TRF1 and with increased levels of hTERT, P53 and c-myc.
Assuntos
Neoplasias Ósseas/genética , Osteossarcoma/genética , Proteínas de Ligação a Telômeros/metabolismo , Telômero/ultraestrutura , Adulto , Neoplasias Ósseas/metabolismo , Condrossarcoma/genética , Condrossarcoma/metabolismo , Feminino , Humanos , Hibridização in Situ Fluorescente/métodos , Lipossarcoma/genética , Lipossarcoma/metabolismo , Masculino , Pessoa de Meia-Idade , Osteossarcoma/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Rabdomiossarcoma/genética , Rabdomiossarcoma/metabolismo , Complexo Shelterina , Telomerase/genética , Telomerase/metabolismo , Proteínas de Ligação a Telômeros/genética , Proteína 1 de Ligação a Repetições Teloméricas/genética , Proteína 1 de Ligação a Repetições Teloméricas/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
OBJECTIVE: To evaluate the expression of TEIF protein in human tumors of soft tissue and its significance. METHODS: Anti-TEIF polyclonal antibody was generated by immunization of E.coli expressed His-TEIF protein. The expression of TEIF in 166 cases of sarcomas and 28 case benign tumors or tumor-like lesions of soft tissue arranged in tissue chip was analyzed by immunohistochemistry. RESULTS: Polyclonal antibody obtained from immunized rabbit was verified in Western blot to prove its specific reactivity with native TEIF protein. The immunohistochemical staining of TEIF showed that about 58% (97/166) of sarcomas were positive and significantly different from that of benign tumors or tumor-like lesions (11%, 3/28). The positive staining was predominantly in synovial sarcoma 94% (16/17), primitive neuroectodermal tumor (PNET) 91% (21/23), both of which were significantly higher than 43% (6/14) of dermatofibrosarcoma protuberans, 38% (6/16) of myxofibrosarcoma, 36% (8/22) of malignant peripheral nerve sheath tumor, 32% (6/19) of liposarcoma, (P < 0.05, respectively), but not higher than 75% (15/20) of malignant fibrous histiocytoma, 70% (7/10) of rhabdomyosarcoma or 64% (9/14) of leiomyosarcoma. Meanwhile, strong positive staining of TEIF (>or= 2+) was frequently observed in PNET (83%, 19/23) and synovial sarcoma (76%, 13/17). With respect to FNCLCC grading, 19 cases of grade I sarcoma TEIF was 32% (6/19) and strong positive was 11% (2/19), 44 cases of grade II sarcoma was 48% (21/44) and 32% (14/44), and 70 of grade III was 84% (59/70) and 70% (49/70). The rate of either positive or strong positive in grade III sarcoma was significantly different from that of either grade I or II (P < 0.05), but no difference between the latter two groups (P > 0.05). CONCLUSIONS: TEIF protein could be detected in large part of soft tissue sarcomas, and it not only over-expressed in most of PNET, synovial sarcomas, but also correlated with histological grading.
