The Hippo pathway, asymmetric cell division and the tolerance to aneuploidy in cancer cells

• Grant number: 16/24234-9
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: May 01, 2017
• End date: April 30, 2018
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Principal Investigator: Oswaldo Keith Okamoto
• Grantee: Beatriz de Araujo Cortez
• Supervisor: Neil Ganem
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Boston University (BU), United States
• Associated to the scholarship: 14/10519-6 - Hippo signaling pathway and asymmetric division of cancer stem cells derived from human medulloblastoma, BP.PD

Abstract

Hippo pathway is a phosphorylation cascade that culminates in YAP inactivation, inhibiting its activity as a transcription factor. Initially, Hippo pathway was related to the control of cell proliferation, tissue growth and stem cells phenotype. In addition, the inhibition of this pathway and hyperactivation of YAP have been related to several types of cancer. Efforts have been done to elucidate the mechanisms by which Hippo pathway and YAP activity favors cancer development. Recent data using normal cells showed that Hippo pathway is important to inhibit the proliferation of tetraploid cells, suggesting that Hippo and YAP activity can be related to chromosome instability and aneuploidy. This relation has never been observed in cancer cells. During the development of our project in Brazil, the investigation of how Hippo pathway modulates asymmetric cell division of cancer stem cells revealed that in some cases YAP segregates asymmetrically during mitosis, generating daughter cells with different levels of the protein. The aim of the current project is to elucidate the molecular mechanisms that control YAP asymmetric segregation during mitosis and how its activation can interfere with chromosome instability and genetic heterogeneity in cancer cells. For that, we will evaluate if the segregation of YAP and its modulators (Hippo pathway and actin) are correlated during mitosis using high-resolution confocal microscopy. To mimic the behavior of daughter cells with different levels of YAP, we will generate YAP knockout and overexpressing cells lines. It will be possible to relate YAP activity and induction of chromosome instability by the analysis of chromosome segregation, chromatin bridges and micronuclei formation by time-lapse imaging. To investigate the tolerance to chromosomal instability and how YAP activity can favors genetic heterogeneity, aneuploidy levels will be quantified after the induction of chromosome missegregation in YAP+ and YAP-/- cells. (AU)