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| Author(s): |
Rodrigo Ribeiro da Silva
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2010-06-11 |
| Examining board members: |
Enilza Maria Espreafico;
Carlos Gilberto Carlotti Junior;
Sergio Vicente Serrano
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| Advisor: | Enilza Maria Espreafico |
| Abstract | |
The KIAA0090 gene, which has been found in all eukaryotic genomes and is predicted to encode a highly conserved transmembrane protein, maps to a chromosomal region (1p36.13) with frequent aberrations in some human tumors. In addition, publicly available expression data suggest altered expression of this gene associated with many tumors and treatments. The goals of this work were to search for the occurrence of multiple KIAA0090 transcripts in melanoma cell lines; determine the gene expression pattern in different cell lines and tumor types by real time RT-PCR; and analyze the gene knockdown effect on melanoma cell viability. The transcript that we found to be expressed in melanoma cell line seems to correspond to RefSeq transcript. In melanoma, increased KIAA0090 expression was found in all human melanoma cell lines in comparison to melanocytes. Interestingly, however, we observed significantly higher expression of KIAA0090 in nevi samples (mean value = 11,02) as compared to primary (mean value = 2,87) or metastatic (mean value = 2,72) melanoma groups (p<0,01), although there was no significant difference between primary and metastatic melanoma. Treatment of melanoma cells with an inhibitor of DNA methylation (5-Aza-2\'- deoxycytidine) and /or deacetylation of histones (Trichostatin A) leads to an enhancement of KIAA0090 expression, supporting the hypothesis that epigenetic events may be involved in modulating KIAA0090 gene expression. On the other hand, no significant differences in the KIAA0090 mRNA expression levels were observed between white matter and glioblastoma samples, although we found slightly lower survival rates associated with high levels of KIAA0090 mRNA in glioblastomas in a study involving 28 patient samples. Interestingly, this was compatible with database of large scale gene expression studies, which have shown a direct correlation between KIAA0090 up-regulation and low survival rates in patients with glioblastoma (216 patients data analized - https://cma.nci.nih.gov/cma-tcga/). In 31 samples from Acute Lymphocytic Leukemia patients, we could not find any relationship between the KIAA0090 gene expression and patient age, sex, white blood cell count, risk, immunophenotype, response and patient\'s current situation. KIAA0090 knockdown led to an increase of cell death rate in a melanoma cell line, and since unviable cells are Annexin V positive, we postulate that they undergo apoptotic death. The data obtained, and the ones deposited in databases, confirms changes in expression of KIAA0090 during tumor progression. Pre-neoplasic lesions such as nevi already have changes in KIAA0090 expression, comparable to oncogene BRAF. As for other molecules involved in the UPR and ERAD pathways, KIAA0090 knockdown induces apoptotic cell death. Therefore, KIAA0090 gene seems to be very important in helping maintain the tumorigenic ability of cells in not suitable environments. (AU) | |