Investigating the role of amplified centrosomes in tumourigenesis of breast cancer

Centrosomes, the major microtubule organising centre (MTOC) of cell play essential roles in regulating cell cycle control, spindle assembly and genomic stability. Centrosome amplification (CA), a numerical centrosomal defect (≥3 centrosomes per cell) is a hallmark feature of many high-grade human tumours, including breast. CA can be triggered by DNA damage and centrosome abnormalities resulting genomic instability, aneuploidy, tumourigenesis and metastasis. However, the intracellular mechanisms behind CA induced tumourigenesis evolving to tumour aggressiveness remain unclear. In this study, CA effects on early tumourigenesis and progression were explored using non tumourigenic breast epithelial cell line MCF10A capable of tetracycline-mediated transient overexpression of centrosome duplication regulatory gene PLK4. This study shows that PLK4 overexpression induced CA increases cellular invasion and migration in MCF10A cells. Conversely blocking CA by centrinone B mediated PLK4 inhibition decreased metastatic potential in TNBC cell line MDA-MB-231. Validation of in vitro findings in an in vivo chick chorioallantoic membrane (CAM) model, revealed the novel discovery that CA is capable of inducing angiogenesis along with cellular invasion as a downstream effect of increased pro-angiogenic factor secretions (IL-8) and activation of the uPA/PAI-1 system. We found that CA drives cell invasiveness by altering cell-cell and cell-ECM contacts by dysregulating cell junction proteins (ZO-1, Occludin & β catenin) protein expression and localisation, increased cell-ECM attachment and promoted ECM degradation by increasing integrin β3 and MMP1 and MMP13 production possibly via a Rap-1 mediated pathway. Furthermore, the in silico analysis of verified CA20 gene panel with a novel cell junction/adhesion (CJ30) gene panel in the human cancer TCGA data set unveiled the strong correlation between the CA and cell junction gene dysregulation in breast cancer and pan cancer. These findings collectively highlight the possible cellular pathways by which CA triggers early tumourigenesis, promoting angiogenesis, cell invasion, and metastasis.

Funder

NUIG Hardiman PhD Scholarship
Hardiman Scholarship, National University of Ireland, Galway

Publisher

NUI Galway

Rights

Attribution-NonCommercial-NoDerivs 3.0 Ireland

cbn

Collections

University of Galway Theses (PhD Theses)