Characterisation of the involvement of the RECK gene on cell proliferation and tumor progression: inverse correlation with the oncogene expression c-myc

Author(s)

Sheila Maria Brochado Winnischofer

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2005-05-24

Examining board members

Mari Cleide Sogayar; Rafael Linden; Suely Kazue Nagahashi Marie; Sergio Verjovski Almeida; Luisa Lina Villa

• Advisor: Mari Cleide Sogayar

Abstract

This work shows, for the fIrst time, the involvement of the RECK gene in cell cycle progression. Our data shows that the RECK gene product regulates cell cycle progression by altering the G1 to S transition. Also, we show that RECK is able to induce p21 expression and, consequently, lead to hypophosphorylation of the Rb protein, revealing at least one molecular mechanism through which RECK modulates the cell cycle progression. It has been described that induction of the c-Myc transcription factor promotes cell proliferation and cell transformation by regulating several genes that are involved in cell cycle progression. Here, we show that activation of a Mycestrogen receptor fusion protein with 4-hydroxytamoxifen in mouse fibroblasts was suffIcient to repress the expression of the RECK gene, by acting at the RECK promoter region. In addition, we show that Myc-responsiveness seems to be mediated by the upstream Sp1 sites and to be dependent on cromatin remodelling mechanisms. RECK gene expression was aIso evaluated during human glioma progression. Our results indicate that RECK gene expression is not altered during glioma progresslOn, but a correlation was found between the abundance of RECK expression in gliomas and patient survival. The levels of RECK expression can be considered a good prognostic indicator for glioma patients. Better understanding of RECK gene regulation may contribute to uncover the mechanisms of cell cycle and tumor progression, and to the development of new strategies for cancer prevention and therapeutic intervention. (AU)