932 resultados para P19 embryonal carcinoma cells


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Pós-graduação em Ginecologia, Obstetrícia e Mastologia - FMB

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Tumor response to antineoplastic drugs is not always predictable. This is also true for bladder carcinoma, a highly recurrent neoplasia. Currently, the combination of cisplatin and gemcitabine is well accepted as a standard protocol for treating bladder carcinoma. However, in some cases, this treatment protocol causes harmful side effects. Therefore, we investigated the roles of the genes TP53, RASSF1A (a tumor suppressor gene) and hMLH1 (a gene involved in the mismatch repair pathway) in cell susceptibility to cisplatin/gemcitabine treatment. Two bladder transitional carcinoma cell (TCC) lines, RT4 (wild-type TP53) and 5637 (mutated TP53), were used in this study. First, we evaluated whether the genotoxic potential of cisplatin/gemcitabine was dependent on TP53 status. Then, we evaluated whether the two antineoplastic drugs modulated RASSF1A and hMLH1 expression in the two cell lines. Increased DNA damage was observed in both cell lines after treatment with cisplatin or gemcitabine and with the two drugs simultaneously, as depicted by the comet assay. A lack of RASSF1A expression and hypermethylation of its promoter were observed before and after treatment in both cell lines. On the other hand, hMLH1 downregulation, unrelated to methylation status, was observed in RT4 cells after treatment with cisplatin or with cisplatin and gemcitabine simultaneously (wild-type TP53); in 5637 cells, hMLH1 was upregulated only after treatment with gemcitabine. In conclusion, the three treatment protocols were genotoxic, independent of TP53 status. However, cisplatin was the most effective, causing the highest level of DNA damage in both wild-type and mutated TP53 cells. Gemcitabine was the least genotoxic agent in both cell lines. Furthermore, no relationship was observed between the amount of DNA damage and the level of hMLH1 and RASSF1A expression. Therefore, other alternative pathways might be involved in cisplatin and gemcitabine genotoxicity in these two bladder cancer cell lines.

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Background: Cancer pain severely limits function and significantly reduces quality of life. Subtypes of sensory neurons involved in cancer pain and proliferation are not clear.Methods: We produced a cancer model by inoculating human oral squamous cell carcinoma (SCC) cells into the hind paw of athymic mice. We quantified mechanical and thermal nociception using the paw withdrawal assays. Neurotoxins isolectin B4-saporin (IB4-SAP), or capsaicin was injected intrathecally to selectively ablate IB4(+) neurons or TRPV1(+) neurons, respectively. JNJ-17203212, a TRPV1 antagonist, was also injected intrathecally. TRPV1 protein expression in the spinal cord was quantified with western blot. Paw volume was measured by a plethysmometer and was used as an index for tumor size. Ki-67 immunostaining in mouse paw sections was performed to evaluate cancer proliferation in situ.Results: We showed that mice with SCC exhibited both mechanical and thermal hypersensitivity. Selective ablation of IB4(+) neurons by IB4-SAP decreased mechanical allodynia in mice with SCC. Selective ablation of TRPV1(+) neurons by intrathecal capsaicin injection, or TRPV1 antagonism by JNJ-17203212 in the IB4-SAP treated mice completely reversed SCC-induced thermal hyperalgesia, without affecting mechanical allodynia. Furthermore, TRPV1 protein expression was increased in the spinal cord of SCC mice compared to normal mice. Neither removal of IB4(+) or TRPV1(+) neurons affected SCC proliferation.Conclusions: We show in a mouse model that IB4(+) neurons play an important role in cancer-induced mechanical allodynia, while TRPV1 mediates cancer-induced thermal hyperalgesia. Characterization of the sensory fiber subtypes responsible for cancer pain could lead to the development of targeted therapeutics.

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It is believed that epigenetic mechanisms such as DNA methylation are important for the tumorigenesis and maintenance of the altered state of tumor cells. DNA methylation occurs by the addition of a methyl group to carbon 5 of cytosine, catalyzed by the enzyme DNA methyl-transferase, which can change the expression of a gene, including the tumor suppressor genes. In human squamous cell carcinoma, several features have shown the etiological role of genes in tumor development. Among them, FOXE1 gene (forkhead box E1 - thyroid transcription factor) is presented with an important role in susceptibility to disease. Similarly the FOXE1 methylation pattern could alter the expression of this gene in dogs and predisposed to tumor on. Therefore, this study aims to investigate in dogs, the validity of the strategy employed in humans to analyze the FOXE1 methylation status. DNA extraction from fresh frozen tumoral samples was performed by Wizard Genomic® DNA Purification Kit. The methylation status was determined by MSP-PCR (methylation-specific polymerase chain reaction), using 2.0 ng of DNA treated with sodium bisulphate. One hundred micrograms of bisulphite-modified DNA was amplified using primers specific for either methylated or unmethylated DNA (primers sequences are available at http://pathology2.jhu.edu/pancreas/primer.pdf). The analysis of fragments was loaded on to 7% polyacrylamide gels and silver nitrate staining. In this stage of technical approach, 60% were FOXE1 hypermethylated. In conclusion, it was observed that the standard technique for assessing the methylation pattern of gene FOXE1 in humans can be used for the same evaluation in dogs. The correlation of these molecular data with clinical and histopathological parameters may have diagnostic and prognostic value and still be used as a tumor marker for therapeutic decision and surgical approach

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