The role and therapeutic potencial of regulators and effectors of PI3K/Akt pathway in T-cell leukemia

• Author(s): Ribeiro, Daniel Filipe Silva
• Date: 2009
• Persistent ID: http://hdl.handle.net/10451/1502
• Origin: Repositório da Universidade de Lisboa
• Subject(s): Biologia celular; Células T; Leucemia; Teses de mestrado
• Document Type: Master thesis
• Language: Portuguese
• Advisor(s): Barata, João Taborda; Telhada, Maria Margarida Blasques
• Contributor(s): Repositório da Universidade de Lisboa

Description

Tese de mestrado, Biologia (Biologia Molecular Humana), Universidade de Lisboa, Faculdade de Ciências, 2009

T-cell acute lymphoblastic leukemia (T-ALL) is a hematological cancer that mainly affects children. Although current treatments are effective, they originate significant long-term side-effects and significant number of relapses occur. Both microenvironmental and cell-autonomous cues contribute to T-ALL progression. IL-7 is an essential cytokine that has been shown to promote survival and proliferation of T-ALL cells by activating the PI3K/Akt pathway. Notch and CK2 have been implicated in transformation and survival of T-ALL cells by downregulating or functionally inactivating PTEN protein, a tumor suppressor and negative regulator of PI3K/Akt pathway. In the present thesis, two main objectives were defined: to establish the relative importance of two proteins, GSK3ß and FOXO3a, which are negatively regulated by the PI3K/Akt pathway, in IL-7-mediated proliferation and viability of T-ALL cells; and to assess the therapeutic potential of combined Notch and CK2 inhibition in the regulation of the tumor suppressor PTEN. Both objectives can contribute to the rational definition of new therapeutic targets and the development of novel treatment strategies. To accomplish the first task, lentiviral vectors were constructed bearing constitutively active mutants of GSK3ß and FOXO3a (GSK3ß.S9A and FOXO3a.A3). Preliminary data suggest that downregulation of FOXO3a activity may be mandatory for IL-7 to exert its effects upon leukemia cells. T-ALL cells transduced with this mutant show decreased viability and IL-7 stimulation cannot rescue the viability to the control levels. To accomplish the second task, PTEN+ cell lines were incubated with the γ-secretase inhibitor (Notch inhibitor) DAPT, the CK2 inhibitors DRB or TBB, or with both. Our results show that the combined use of γ-secretase and CK2 inhibitors can affect the cell size, cell number and proliferation of T-ALL cell lines in a cooperative manner.

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