Repositório RCAAP

Dissertação (mestrado) — Universidade de Brasília, Faculdade de Medicina, Programa de Pós-Graduação em Ciências Médicas, 2022.

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancer types. Activating oncogenic KRAS mutations are commonly observed in PDAC; however, oncogenic KRAS amplification is rarely observed, and its significance in prognosis and resistance to therapy remains poorly characterized. The present report describes the case of a 52‑year‑old male patient diagnosed with advanced PDAC with liver metastasis. The patient received modified FOLFIRINOX (mFFX) therapy to which the patient became intolerant with a strong inflammatory response. Subsequent treatment with gemcitabine plus nab‑paclitaxel failed to control the disease. Targeted genetic analysis revealed KRASG12D and TP53R248Q mutations in the primary tumor and liver metastases. Analysis of circulating tumor DNA (ctDNA) before the first line of treat‑ ment confirmed these genetic findings and revealed a >4‑fold amplification of the mutant KRASG12D not detected in the primary tumor. Additionally, subsequent analysis confirmed a 5‑fold amplification of the KRASG12D allele in liver metastasis. Consecutive monitoring of ctDNA revealed an initial decrease in the tumor burden 2 weeks after the first cycle of mFFX. However, coinciding with treatment intolerance, a sharp increase in tumor mutational levels and KRASG12D amplifica‑ tion was observed 1 month later. The patient died 70 days after treatment initiation. Overall, amplification of oncogenic KRASG12D was not only associated with an aggressive pheno‑ type, but also supported cancer resistance to chemotherapy. Importantly, this case suggests that plasma detection of KRASG12D amplification is feasible in the clinical routine and constitutes a powerful tool for assessing tumor aggressiveness.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, 2009.

BACKGROUND: The inhibition of the enzyme telomerase (TERT) has been widely investigated as a new pharmacological approach for cancer treatment, but its real potential and the biochemical consequences are not totally understood. OBJECTIVE: Here, we investigated the effects of the telomerase inhibitor MST-312 on a human glioma cell line after both short- and long-term (290 days) treatments. METHODS: Effects on cell growth, viability, cell cycle, morphology, cell death and genes expression were assessed. RESULTS: We found that short-term treatment promoted cell cycle arrest followed by apoptosis. Importantly, cells with telomerase knock-down revealed that the toxic effects of MST-312 are partially TERT dependent. In contrast, although the long-term treatment decreased cell proliferation at first, it also caused adaptations potentially related to treatment resistance and tumor aggressiveness after long time of exposition. CONCLUSIONS: Despite the short-term effects of telomerase inhibition not being due to telomere erosion, they are at least partially related to the enzyme inhibition, which may represent an important strategy to pave the way for tumor growth control, especially through modulation of the non-canonical functions of telomerase. On the other hand, long-term exposure to the inhibitor had the potential to induce cell adaptations with possible negative clinical implications.

Background Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm whose pathogenesis is linked to the Philadelphia chromosome presence that generates the BCR–ABL1 fusion oncogene. Tyrosine kinase inhibitors (TKI) such as imatinib mesylate (IM) dramatically improved the treatment efficiency and survival of CML patients by targeting BCR–ABL tyrosine kinase. The disease shows three distinct clinical-laboratory stages: chronic phase, accelerated phase and blast crisis. Although patients in the chronic phase respond well to treatment, patients in the accelerated phase or blast crisis usually show therapy resistance and CML relapse. It is crucial, therefore, to identify biomarkers to predict CML genetic evolution and resistance to TKI therapy, considering not only the effects of genetic aberrations but also the role of epigenetic alterations during the disease. Although dysregulations in epigenetic modulators such as histone methyltrasnferases have already been described for some hematologic malignancies, to date very limited data is available for CML, especially when considering the lysine methyltransferase MLL2/KMT2D and MLL3/KMT2C. Methods Here we investigated the expression profile of both genes in CML patients in different stages of the disease, in patients showing different responses to therapy with IM and in non-neoplastic control samples. Imatinib sensitive and resistant CML cell lines were also used to investigate whether treatment with other tyrosine kinase inhibitors interfered in their expression. Results In patients, both methyltransferases were either upregulated or with basal expression level during the chronic phase compared to controls. Interestingly, MLL3/KMT2C and specially MLL2/KMT2D levels decreased during disease progression correlating with distinct clinical stages. Furthermore, MLL2/KMT2D was decreased in patients resistant to IM treatment. A rescue in the expression of both MLL genes was observed in KCL22S, a CML cell line sensitive to IM, after treatment with dasatinib or nilotinib which was associated with a higher rate of apoptosis, an enhanced expression of p21 (CDKN1A) and a concomitant decrease in the expression of CDK2, CDK4 and Cyclin B1 (CCNB1) in comparison to untreated KCL22S control or IM resistant KCL22R cell line, which suggests involvement of p53 regulated pathway. Conclusion Our results established a new association between MLL2/KMT2D and MLL3/KMT2C genes with CML and suggest that MLL2/KMT2D is associated with disease evolution and may be a potential marker to predict the development of therapy resistance.

Elucidating the conformational heterogeneity of proteins is essential for understanding protein function and developing exogenous ligands. With the rapid development of experimental and computational methods, it is of great interest to integrate these approaches to illuminate the conformational landscapes of target proteins. SETD8 is a protein lysine methyltransferase (PKMT), which functions in vivo via the methylation of histone and nonhistone targets. Utilizing covalent inhibitors and depleting native ligands to trap hidden conformational states, we obtained diverse X-ray structures of SETD8. These structures were used to seed distributed atomistic molecular dynamics simulations that generated a total of six milliseconds of trajectory data. Markov state models, built via an automated machine learning approach and corroborated experimentally, reveal how slow conformational motions and conformational states are relevant to catalysis. These findings provide molecular insight on enzymatic catalysis and allosteric mechanisms of a PKMT via its detailed conformational landscape.

Cancer is comprised of a multitude of epigenetic abnormalities, including the global loss and regional gain of DNA methylation as well as alterations in histone methylation. Here, we characterize a new methyltransferase, SET domain-containing protein 4 (SETD4), which is involved in breast carcinogenesis. Quantitative real-time PCR (qPCR) showed elevated expression levels of SETD4 in several breast cancer cell lines. SETD4 overexpression was confirmed by western blot analysis suggesting a correlation between high expression of SETD4 and a lack of the estrogen receptor (ER) in breast cancer. In addition, cell fractionation studies and confocal immunofluorescence revealed the nuclear and non-nuclear localization of this new protein. SETD4 knockdown in breast cancer cell lines significantly suppressed their proliferation and delayed the G1/S cell cycle transition without affecting apoptosis. Furthermore, western blot analysis showed that knockdown of SETD4 decreased cyclin D1 expression, revealing the involvement of SETD4 in cell cycle regulation. These data imply that SETD4 plays a crucial role in breast carcinogenesis and could be a novel molecular target for the development of new strategies for the diagnosis and treatment of breast cancer.

Dissertação (mestrado) — Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2022.

Tese (doutorado) — Universidade de Brasília, Faculdade de Ceilândia, Programa de Pós-Graduação em Ciências e Tecnologias e Saúde, 2022.

Tese (doutorado) — Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2022.

Tese (doutorado) — Universidade de Brasília, Faculdade de Ciências Médicas, Programa de Pós-Graduação em Ciências Médicas, 2022.

Dissertação (mestrado) — Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Departamento de Economia, Programa de Pós-Graduação em Ciências Econômicas, 2022.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Psicologia, Departamento de Processos Psicológicos Básicos, Programa de Pós-Graduação em Ciências do Comportamento, 2009.

Tese (doutorado) — Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2022.

Tese (doutorado) — Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, 2022.

Dissertação (mestrado) — Universidade de Brasília, Faculdade de Direito, Programa de Mestrado Profissional em Direito, Regulação e Políticas Públicas, 2022.

Dissertação (mestrado) — Universidade de Brasília, Faculdade de Direito, Programa de Pós-Graduação em Direito, 2022.

Tese (Doutorado) — Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Ciências Da Saúde, 2022.

Dissertação (mestrado) — Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2022.

Background: The endodontic treatment of calcified root canals in molars is a challenging and time-consuming procedure. Even with the aid of a surgical microscope, the risk of root perforation is high, especially in the furcation area. The purpose of this study is to report the Computer-Aided-Design and Manufacturing (CAD–CAM) workflow, the innovative strategies for the template ideation, and the guided endodontic treatment of a mandibular molar with dystrophic calcification in the mesial root canals. Case presentation: A 58-year-old female patient, ASA I, was referred to endodontic treatment in the right first mandibular molar for prosthetic reasons. The mesiobuccal and mesiolingual canals appeared obliterated in the radiographic images. The absence of dental crown, tooth inclination, and the limited mouth opening of the region contributed to a poor visual reference of the tooth in the dental arch and the direction of the remaining lumens of the canals. Despite using surgical microscopy, the conventional technique led to the deviation of the mesiobuccal canal towards the furcation area. The obliteration of both mesial root canals was confirmed using the Cone Beam Computer Tomography. The clinical history associated with the tomography diagnosis was compatible with dystrophic calcifica tions in the pulp canals. The patient was submitted to an intra-oral scanning as well. The Digital Imaging and Commu nications in Medicine data (DICOM) were segmented. The Standard Tessellation Language (STL) files were processed following the CAD–CAM workflow, aiming to create two different endodontic templates with a new open design concept. The templates with open design allowed direct visualization of the operative field, irrigation, and dentin debris removal. The strategy of the guidance sleeves niche as half-cylinders allowed the drill insertion in a limited mouth opening region. Conclusions: The digital planning and guided access permitted to overcome the case limitations and then re-establish the glide path following the original anatomy of the root canals. The guided endodontic represents a personalized technique that provides security, reduced risks of root perforation, and a significant decrease of the working time to access obliterated root canals even in the mesial root canal of mandibular molars, a region of limited mouth opening.