Signalling platforms in normal and transformed cells: molecular and functional characterisation and translational strategies


Paola Defilippi

It is well known that when cells become transformed and malignant, they acquire anchorage-independent growth and invasive properties. It is also well established that the signalling originated from the integrin family of cell-matrix receptors is central to the conversion from a normal to a tumour phenotype leading to cell transformation and cancer cell progression (Cabodi and Defilippi, 2006). In our lab we have contributed to define that integrin-dependent adhesion and growth factor/cytokine stimulation co-ordinately regulate convergent signalling pathways that control cell growth, spreading and migration in normal cells (Moro et al., 1998, 2002; Cabodi, Morello et al. 2009; Defilippi et al., 2005), . Therefore understanding the molecular mechanisms by which integrins and growth factors co-operate in the control of cell growth, migration and survival from apoptosis is a fundamental relevant task to the study of cell transformation. 
Increasing evidences indicate that integrins co-operate with growth factor receptors in the control of cell survival and proliferation, by formation of macromolecular transducing complexes. In this context we have identified three main signalling platforms into the cells.

  1.  A platform constituted by integrins and the EGF receptor, essential for full activation of EGFR in response to EGF, and for EGF-dependent downstream signalling (Cabodi and Defilippi, 2006; Cabodi, Morello et al., 2009).
  2. A platform formed by the adaptor protein p130Cas. Due to the presence of multiple conserved sequence motifs and extensive post-translational modifications, it promotes protein-protein interactions leading to multi-protein complexes (Defilippi et al., 2006). In normal cells, interaction of p130Cas with other proteins modulates cell motility, survival and proliferation. We have already determined the involvement of p130Cas in mammary gland development and tumorigenesis (Cabodi et al., 2006) and we are in the process of analysing the involvement of p130Cas in cell transformation.

A platform formed by the adaptor protein p140Cap. We recently identified p140Cap as a novel adaptor protein and a downstream effector of cell-matrix and growth factor signalling (Di Stefano et al., 2004; Di Stefano, Damiano et al., 2007). our data show that p140Cap controls Src kinase activity, resulting in decreased cell proliferation, motility and invasion, both in vivo and in vitro, thus regulating tumorigenic properties of breast cancer cells. Over-expression of the p140Cap adaptor might thus constitute a potential tool to revert cancer cells to a more differentiated, less invasive phenotype.

Based on these results we are currently characterising these molecules with molecular and functional approaches, using the following models:

  • In vitro cell cultures from breast, lung and colon tumours, over-expressing or silenced for specific components of the different platforms
  • Transgenic mice over-expressing p130Cas and p140Cap in the mammary gland 
  • Selective inhibitors for preclinical studies 
  • Normal and cancer stem cells derived from the transgenic mice. 
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