Colorectal cancer has a 9.8% cumulative incidence rate, making it the third most common cancer in the Western world. Despite a 50-60% response rate in patients to current cancer therapies, drug resistance and tumour relapse remain a concern. While current therapies reduce the tumour mass, they possibly fail to eradicate a unique population of pluripotent tumour resident cells. These cells, known as cancer stem cells, may have similar properties of self-renewal and proliferation to embryonic and adult stem cells, as they also express a number of key pluripotent transcription factors, including amongst others, NANOG, OCT3/4 and SOX2. Furthermore, since discreet groups of such stem cells are proposed to essentially drive tumourigenesis, they present as potential novel targets for cancer therapy. This study aimed to isolate a putative CSC population from the advanced colon adenocarcinoma cell lines HT29 and DLD1 and to assess the therapeutic effects of the epigenetic drugs Valproic acid and Zebularine on pluripotent gene expression.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 4 uppsatser.

Thesis (Ph.D.). / Written for the Dept. of Biochemistry. Title from title page of PDF (viewed 2008/05/09). Includes bibliographical references.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Oct. 9, 2008). Includes bibliographical references (p. 89-101).

Orientador: Jose Barreto Campello Carvalheira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T01:08:04Z (GMT). No. of bitstreams: 1 Souza_KellenKettyde_M.pdf: 1724833 bytes, checksum: 44f766e2043af515b2f3f9462dc5c5e3 (MD5) Previous issue date: 2007 / Resumo: A resistência dos tumores aos quimioterápicos é um problema clínico comum. Recentemente, foi demonstrado que o bloqueio. da via de sinalização da PI3-quinase aumenta a apoptose induzida pelo SN-38, um metabólito ativo do irinotecano. Entretanto, os mecanismos moleculares destas mudanças ainda não são esclarecidos. Para investigar os eventos moleculares envolvidos no aumento da sinalização na via da PI3-quinase associada ao irinotecano, aspirina e rapamicina foram utilizadas para modular esta via de sinalização. Nós observamos que a aspirina é capaz de inibir a fosforilação do IRS-l, através de seus alvos JNK e IKK, e aumentar o crescimento dos tumores em camundongos Scid previamente injetados com linhagem de adenocarcinoma de cólon (HT29). Adicionalmente, demonstramos que o bloqueio da mTOR reduz a proliferação celular induzida pelo irinotecano. Assim, a ativação da via PI3-quinase/ Akt/mTOR pode contribuir para a quimiorresistência induzi da pelo irinoteco / Abstract: Resistance of tumors to chemotherapeutic agents is a common clinical problem in human cancer. Recently, the blocking of PI3-kinase signaling pathway was shown to enhance apoptosis induced by SN-38, an active form of irinotecan. To gain further insight into the molecular events of irinotecan-associated increase in PI3-kinase signaling pathway, aspirin and rapamycin were used to modulate this signaling pathway. We describe here that aspirin is able to further inhibit IRS-l serine phosphorylation induced by irinotecan through targeting JNK and IKK, thus agonist activation of IRS-l/PI3-kinase pathway blocked the growth-inhibitory effect of irinotecan in HT -29 colon cancer xenografts; our data also demonstrate a synergistic effect of mTOR inhibition and irinotecan on tumor growth. Activation of PI3-kinase/ Akt/mTOR pathway may thus contribute to refTactoriness to treatment with irinotecan / Mestrado / Ciencias Basicas / Mestre em Clinica Medica

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Introdução e Justificativa: O câncer colorretal é a 3ª neoplasia maligna mais incidente no mundo, e apresenta comportamento bastante heterogêneo aos tratamentos instituídos. Conseguir diferenciar os pacientes de acordo com seu prognóstico e comportamento tumoral é um desafio. A biologia molecular, através dos microRNA (miRNA), pode contribuir na identificação do perfil tumoral e ajudar a predizer os desfechos clínicos. Objetivos: Comparar a expressão tecidual de miRNA-92a, miRNA-133a e miRNA-145 de pacientes com câncer de cólon, correlacionando o perfil de expressão de miRNA com aspectos clínicopatológico e prognóstico. Casuística e Métodos: Quantificação de miRNA-92a, miRNA-133a e miRNA-145 pela técnica de reação em cadeia de polimerase em tempo real (RTPCR) em amostras de tecido tumoral em pacientes com câncer esporádico de cólon (grupo de estudo) operados entre janeiro de 2010 a dezembro de 2011 e em amostras de tecido colônico sadio de pacientes saudáveis (grupo controle) submetidos à colonoscopia de rotina para rastreio de câncer colorretal. Os resultados das dosagens de miRNA foram correlacionados ao valor do antígeno cárcinoembrionário (CEA), idade, estadiamento, invasão linfovascular, sobrevida livre de doença e sobrevida global. Resultados: A idade média dos pacientes foi de 66 anos e 60% eram do sexo masculino. No momento do diagnóstico inicial 22% apresentavam metástase à distância, e em 80% dos pacientes foi atingida ressecção R0. A sobrevida global foi de 46 meses e a sobrevida livre de doença foi de 32 meses. Apenas o miRNA-133a esteve hiopoexpresso no grupo de estudo (p=0,0007). Ao se correlacionar os perfis de expressão dos miRNA às variáveis clínico-patológica e prognóstica, a hiperexpressão do miRNA-92a esteve associada a maior sobrevida global (p= 0,044). Discussão: O tempo de espera entre o encaminhamento para hospitais terciários e o início do tratamento oncológico pode contribuir para o elevado índice de pacientes com doença metastática ao diagnóstico. Melhores desfechos têm sido associados a hospitais de maior volume, aparentemente devido à maior expertise de que esses hospitais possuem. O miRNA-133a, um supressor tumoral, tem sido hipoexpresso em amostras tumorais quando comparadas a tecidos sadios. Por sua vez, a hiperexpressão do promotor tumoral miRNA-92a que esteve associada a melhor prognóstico, pode ser explicada por uma desregulação dos genes alvo desse miRNA ou por diferenças geográficas na expressão dos miRNA. Conclusão: o miRNA-133a encontra-se hipoexpresso em amostras tumorais, enquanto que a hiperexpressão do miRNA-92a esteve associada a melhor sobrevida global. / Introduction: Colorectal cancer is the 3rd most common malignancy in the world, and their incidence has been increase in the last decades. Although patients diagnosed with early stage tumors have more than 65% of overall survival, behavior of colorectal tumors and their response to established treatments is quite heterogeneous. Gap: In this context, becomes interesting differentiate patients according to their prognosis and tumor behavior. Molecular biology through the miRNA quantification can improve the identification of tumor profile and predict clinical outcomes. Propose: Evaluate tumor profile tissue expression of miRNA- 92a, miRNA- 133a and miRNA-145 in patients with non-hereditary colon cancer, correlating with clinicopathological variables and oncological outcomes. Assessing the ability of the expression of these miRNA predict the prognosis. Methods: A dosage of miRNA-92a, miRNA-133a and miRNA-145 was performed in tumor tissue samples from patients with colon cancer (called study group) and non-tumoral colonic tissue samples from healthy patients (called the control group) by real-time polymerase chain reaction. The results of miRNA levels were correlated with clinicopathological data and oncological outcomes. Results: Mean age was 66 years and 60% was male. At initial diagnosis, 22% of lesions had distant metastasis. R0 resection was achieved in 80% of patients. Disease-free survival was 32 months, and overall survival was 46 months. The MiRNA-133a showed higher values in the control group when compared to the study group (p = 0.0007), and miRNA-92a was associated with higher overall survival (p = 0.044). Discussion: Better outcomes in highly specialized centers could be explained by advances in surgical technique and perioperative care. MiRNA-133a was underexpressed in colonic tumoral tissue, likely others tumors. MiRNA-92a overexpression was associated with improve overall survival. It could be explained through deregulation of target genes or geographic patterns of miRNA expression. Conclusion: MiRNA-133a was underexpressed in study group, and over expression of miRNA-92a was associated with better overall survival.

Colon cancer, a disease in which malignant tumors form in the tissues of colon, is the first commonest cancer and the second leading cause of cancer-related deaths in Hong Kong. The standard treatment options for colon cancer include surgery and chemotherapy. However, multidrug resistance (MDR) develops in nearly all patients with colon cancer. In fact, most of the cancer-related deaths are due to chemotherapy failure caused by MDR, which occurs during the course of cancer progression and chemotherapy. Thus, the reversal of MDR plays an important role in the successful chemotherapy for colon cancer. This study investigated such a pharmacological action in reversing MDR in colon cancer cells by tanshinones, targeting the two common mechanisms responsible for MDR, i.e. overexpression of ATP-binding cassette (ABC) transporters and suppression of apoptosis. / Overexpression of P-glycoprotein (P-gp), one of the most important ABC transporters, can mediate the efflux of drugs out of cancer cells, leading to MDR and chemotherapy failure. The reversal of P-gp-mediated MDR by five tanshinones including tanshinone I, tanshinone IIA, cryptotanshinone, dihydrotanshinone and miltirone was evaluated in colon cancer cells. Bi-directional transport assay showed that only cryptotanshinone and dihydrotanshinone decreased the P-gp-mediated digoxin efflux in Caco-2 cells. The two tanshinones potentiated the cytotoxicities of doxorubicin and irinotecan in P-gp overexpressing colon cancer SW620 Ad300 cells. Moreover, these two tanshinones also increased intracellular accumulation of P-gp substrate in SW620 Ad300 cells, presumably by down-regulating P-gp mRNA and protein levels, as well as inhibiting P-gp ATPase activity. / Suppression of apoptosis can lead to MDR in cancer cells to anticancer agents with pro-apoptotic property. Hence, this study also investigated the circumvention of resistance to apoptosis in drug resistant colon cancer cells by cryptotanshinone and dihydrotanshinone, two potential MDR-reversing tanshinones. The drug resistant SW620 Ad300 cells were still sensitive to both cryptotanshinone and dihydrotanshinone in the promotion of cell death. When compared with the parental SW620 cells, the two tanshinones induced less apoptosis but more autophagy in the drug resistant cells. Further studies showed that cell viability was increased after inhibition of autophagy by siRNA interference or autophagy inhibitor. Thus, autophagy induced by the two tanshinones was pro-cell death in SW620 Ad300 cells, which could overcome resistance to apoptosis. / In addition, suppression of apoptosis can be caused by p53 defects/mutations, which were found in more than 50% of all human cancers. Our results also showed that apoptosis and autophagy induced by cryptotanshinone and dihydrotanshinone were independent of the status of p53 in colon cancer cells. The p53-independent cytotoxic actions of the two tanshinones could be useful in overcoming resistance to apoptosis in cancer cells caused by p53 defects/mutations. / Taken together, the current findings indicate a great potential of cryptotanshinone and dihydrotanshinone in the reversal of MDR caused by P-gp overexpression and suppression of apoptosis. They are promising candidates to be further developed as therapeutic agents in the adjuvant therapy for colon cancer, especially for the multidrug resistant cancer types. / 結腸癌是指形成在結腸組織的惡性腫瘤，在香港常見的癌症中排第一位，亦是香港排第二位的致死癌症。結腸癌的標準治療方案主要包括手術和化療。然而，多藥耐藥是結腸癌成功化療的一個障礙。事實上，大多數癌症引起的死亡都和在癌症的發展和化療的過程中產生的多藥耐藥有關。因此，多藥耐藥的逆轉對於結腸癌的成功化療非常重要。本研究旨在通過針對多藥耐藥兩種常見的機制ABC跨膜蛋白的過表達和抑制的細胞凋亡來探討丹參酮對結腸癌細胞多藥耐藥的逆轉。 / P-gp的過表達可介導藥物排出癌細胞，從而導致多藥耐藥和化療失敗。本研究評價了tanshinone I，tanshinone IIA，cryptotanshinone，dihydrotanshinone和miltirone對P-gp介導的結腸癌細胞多藥耐藥的逆轉。雙向轉運實驗表明，只有cryptotanshinone和dihydrotanshinone可以減少P-gp介導的digoxin外排。這兩個丹參酮可以增加doxorubicin和irinotecan在P-gp過表達的結腸癌SW620 Ad300細胞中的毒性。此外，這兩個丹參酮也增加P-gp底物在SW620 Ad300細胞內的積累，推測是通過下調P-gp的mRNA和蛋白水平，以及抑制P-gp的ATP酶活性。 / 抑制的細胞凋亡可導致腫瘤細胞對促凋亡的抗癌藥物产生多藥耐藥。因此，本研究也探討了cryptotanshinone和dihydrotanshinone能否克服結腸癌細胞的凋亡耐受。結果表明cryptotanshinone和dihydrotanshinone仍然能够杀死耐藥的SW620 Ad300細胞。當與SW620細胞相比，這兩個丹參酮在耐藥細胞中誘導的細胞凋亡較少，但自噬增多。進一步研究表明，這兩個丹參酮誘導的自噬是促進細胞死亡的，從而可以克服細胞的凋亡耐受。 / 此外，p53的缺陷/突變存在於50%以上的人類癌症中，并可以抑制細胞產生凋亡。結果表明，cryptotanshinone和dihydrotanshinone誘導的凋亡和自噬與p53在結腸癌細胞中的表達無關。這兩個丹參酮不依賴於p53的細胞毒性可以用於克服p53缺陷/突變引起的凋亡耐受。 / 綜上所述，本研究結果表明cryptotanshinone和dihydrotanshinone在逆轉P-gp的過表達和抑制的細胞凋亡引起的多藥耐藥中具有巨大潛力。它們可以進一步發展為有前途的治療劑并用於結腸癌的輔助治療，尤其是用於多藥耐藥的結腸癌。 / Hu, Tao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 163-182). / Abstracts also in Chinese. / Title from PDF title page (viewed on 06, December, 2016). / Hu, Tao. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.