RESUMO
A Down's syndrome associated gene, Single Minded 2 gene short form (SIM2-s), is specifically expressed in colon tumors but not in the normal colon. Antisense inhibition of SIM2-s in a RKO-derived colon carcinoma cell line causes growth inhibition, apoptosis, and inhibition of tumor growth in a nude mouse tumoriginicity model. The mechanism of cell death in tumor cells is unclear. In the present study, we investigated the pathways underlying apoptosis. Apoptosis was seen in a tumor cell-specific manner in RKO cells but not in normal renal epithelial cells, despite inhibition of SIM2-s expression in both of these cells by the antisense. Apoptosis was depended on WT p53 status and was caspase-dependent; it was inhibited by a pharmacological inhibitor of mitogen-activated protein kinase activity. Expression of a key stress response gene, growth arrest and DNA damage gene (GADD)45alpha, was up-regulated in antisense-treated tumor cells but not in normal cells. In an isogenic RKO cell line expressing stable antisense RNA to GADD45alpha, a significant protection of the antisense-induced apoptosis was seen. Whereas antisense-treated RKO cells did not undergo cell cycle arrest, several markers of differentiation were deregulated, including alkaline phosphatase activity, a marker of terminal differentiation. Protection of apoptosis and block of differentiation showed a correlation in the RKO model. Our results support the tumor cell-selective nature of SIM2-s gene function, provide a direct link between SIM2-s and differentiation, and may provide a model to identify SIM2-s targets.
Assuntos
Apoptose/genética , Diferenciação Celular/genética , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , Regulação Neoplásica da Expressão Gênica/genética , Fatores de Transcrição/biossíntese , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Linhagem Celular Tumoral , Neoplasias do Colo/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Especificidade de Órgãos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas GADD45RESUMO
We report here a pancreatic cancer drug therapy utility of a gene involved in Down's syndrome. Single Minded 2 gene (SIM2) from Down's Syndrome Critical Region was expressed in pancreatic cancer-derived cell lines as well as in tumor tissues, but not in the normal pancreas. A related member of the SIM family, SIM1, did not show similar specificity. Inhibition by antisense technology of one of the isoforms of SIM2, the short-form (SIM2-s) expression in the CAPAN-1 pancreatic cancer cell line, caused a pronounced growth inhibition and induced cell death through apoptosis. The specificity of antisense was inferred from inhibition of SIM2-s mRNA but not the related members of SIM family. In view of the high mortality rate of pancreatic cancer patients, these findings have important implications for the future of pancreatic cancer treatment.
Assuntos
Neoplasias Pancreáticas/tratamento farmacológico , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Apoptose , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Divisão Celular , Síndrome de Down/genética , Sistemas de Liberação de Medicamentos , Perfilação da Expressão Gênica , Humanos , Neoplasias Pancreáticas/metabolismo , Isoformas de Proteínas/metabolismo , RNA Antissenso/farmacologia , Sensibilidade e Especificidade , Células Tumorais CultivadasRESUMO
We report here a cancer drug therapy use of a gene involved in Down's syndrome. Using bioinformatics approaches, we recently predicted Single Minded 2 gene (SIM2) from Down's syndrome critical region to be specific to certain solid tumors. Involvement of SIM2 in solid tumors has not previously been reported. Intrigued by a possible association between a Down's syndrome gene and solid tumors, we monitored SIM2 expression in solid tumors. Isoform-specific expression of SIM2 short-form (SIM2-s) was seen selectively in colon, prostate, and pancreatic carcinomas but not in breast, lung, or ovarian carcinomas nor in most normal tissues. In colon tumors, SIM2-s expression was seen in early stages. Antisense inhibition of SIM2-s expression in a colon cancer cell line caused inhibition of gene expression, growth inhibition, and apoptosis. The administration of the antisense, but not the control, oligonucleotides caused a pronounced inhibition of tumor growth in nude mice with no major toxicity. Our findings provide a strong rationale for the genes-to-drugs paradigm, establish SIM2-s as a molecular target for cancer therapeutics, and may further understanding of the cancer risk of Down's syndrome patients.
Assuntos
Proteínas de Ligação a DNA/genética , Síndrome de Down/genética , Neoplasias/tratamento farmacológico , Neoplasias/genética , Proteínas Nucleares/genética , Animais , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/genética , Neoplasias do Colo/patologia , DNA Complementar/genética , DNA de Neoplasias/genética , Proteínas de Drosophila , Feminino , Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Nus , Neoplasias/patologia , Oligodesoxirribonucleotídeos Antissenso/genética , Oligodesoxirribonucleotídeos Antissenso/uso terapêutico , Oncogenes , Isoformas de Proteínas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Neoplásico/genética , RNA Neoplásico/metabolismo , Células Tumorais CultivadasRESUMO
The Cancer Genome Anatomy Project (CGAP) database has thousands of Expressed Sequence Tags encompassing both known and novel genes. Bioinformatics of the CGAP database led to the prediction that Single Minded Gene (sim2) could be specific to colon tumors. The sim2 gene is located in a minimum region of the chromosome 21 often implicated in trisomia called Down's Syndrome Critical Region. To date, the sim proteins have not been shown to be involved in cancer. Intrigued by the possible association of a Down's syndrome-related gene to solid tumors, efforts were undertaken to validate the expression specificity. The sim2 isoform (sim2-short-form, sim2-s) expression was seen in carcinomas of colon, pancreas and prostate, but not in corresponding normal tissues. Stage-specific expression of the sim2-s protein was seen in normal matched paraffin sections of the colon tumors. In a matched set of tissues of Benign Prostatic Hyperplasia (BPH) and prostate carcinomas, sim2-s expression was detected in the BPH. The expression specificity of sim2-s in select solid tumors offers both diagnostic and therapeutic potential and warrants additional study.