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| Author(s): |
Tamaya Castro Ribeiro
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD) |
| Defense date: | 2015-01-12 |
| Examining board members: |
Ana Claudia Latrônico Xavier;
Margaret de Castro;
Lucila Leico Kagohara Elias;
Maria Candida Barisson Villares Fragoso
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| Advisor: | Ana Claudia Latrônico Xavier |
| Abstract | |
Introduction: The insulin-like growth factor (IGF) system plays a key role in normal cell growth and development. IGF1R overexpression has been demonstrated in several tumors suggesting that its expression is a prerequisite for cell transformation. We demonstrated IGF1R overexpression in pediatric adrenocortical tumors. Objectives: To induce IGF1R silencing by siRNA in a human adrenocortical cell line NCI H295R and evaluate its effects on cell proliferation and apoptosis. Additionally, evaluate the expression of IGF-1R protein and microRNAs related to its transcription in human adrenocortical tumors. Patients and methods: The human adrenocortical tumor cell line NCI H295R was cultured and treated with 2 specific IGF1R siRNA. All experiments were carried out in four groups: (1) untreated NCI H295R cells, (2) NCI H295R cells transfected with specific IGF1R siRNA # 1, (3) NCI H295R cells transfected with specific IGF1R siRNA # 2 and (4) NCI H295R cells transfected with a negative control. IGF-1R gene and protein expression was determined by the techniques of real-time PCR and Western blot, respectively. We assessed the effects of IGF-1R silencing on cell proliferation and apoptosis. Moreover, 202 patients with adrenocortical tumors were selected for the study of IGF-1R protein expression by immunohistochemistry. In the analysis of microRNAs that are related to IGF1R (miR-100, 375, 145 e 126) by real time PCR, 32 out 202 patients were selected. Results: IGF-1R levels were significantly decreased in cells that were treated with IGF-1R siRNA # 1 and siRNA # 2. The relative values of IGF1R mRNA decreased approximately 50% and Western blot analysis revealed a 30% of reduction in IGF-1R protein. Downregulation of this gene was accompanied by a reduction in 40% of cell growth in vitro and an increase in 45% of apoptosis. The analysis of microRNAs demonstrated that IGF1R expression is not correlated with the expression of these small RNAs. Additionally, the analysis of IGF-1R protein expression in human adrenocortical tumors revealed that strong expression (20%) of IGF-1R was more common in adult carcinomas. Moreover, the nuclear IGF-1R was more frequent in carcinomas diagnosed in adults (19%) when compared to adenomas. Conclusions: These data demonstrate the importance of IGF-1R in tumorigenic pathways of malignant neoplasms of the adrenocortical gland. IGF-1R silencing could inhibit tumor growth in vitro by reducing cell proliferation and increasing apoptosis in a cell line of human adrenocortical carcinoma. Furthermore, nuclear IGF-1R expression was more frequent in carcinomas diagnosed in adults, suggesting that IGF-1R may be a biological marker of this neoplasia (AU) | |
| FAPESP's process: | 10/09503-7 - Analysis of IGF1R gene silencing effects in human adrenocortical tumors lines. |
| Grantee: | Tamaya Castro Ribeiro |
| Support Opportunities: | Scholarships in Brazil - Doctorate |