Poster Presentation 25th Lorne Cancer Conference 2013

The contribution of stromal caveolin-1 to breast cancer metastasis. (#128)

Allan D Burrows 1 , Robin L Anderson 1
  1. Peter MacCallum Cancer Centre, East Melbourne, VIC, Australia

In a previous study, our group has shown that the expression of caveolin-1 (CAV1) in normal tissue surrounding a primary breast cancer is a powerful prognostic indicator of subsequent metastatic disease. Whilst reports linking expression of CAV1 within breast tumour cells to clinical outcome have not led to any clear conclusions, our finding of a strong positive correlation between loss of CAV1 expression in breast tumour stroma and poor prognosis (p<0.0001) (Sloan et al., 2009, AJP 174: 2035-2043), is novel and exciting as it offers the potential of a reliable prognostic indicator of metastatic disease.

Tumours arising from non- or weakly metastatic mammary cells grow at a faster or similar rate when co-injected with CAV1 null mammary fibroblasts. In contrast, co-injection with CAV1 expressing mammary fibroblasts has a suppressive effect on tumour growth. To mimic this phenotype observed in vivo, 3D co-culture assays are being developed, and although they have demonstrated a positive effect of fibroblasts on tumour cell migration and proliferation, no stromal CAV1 specific effect has been observed.

To further understand the consequences of the loss of stromal CAV1, profiling of CAV1 expressing and null mouse mammary fibroblasts was conducted using cytokine arrays and cDNA microarrays. Differences in the secretion of known CAV1 associated cytokines such as RANTES, Gas6 and IL-6 were observed, with no significant changes in their expression.

Based on these findings, CAV1 may be contributing directly to the progression of breast cancer and thus provide the basis of a stromal targeted therapy. An understanding of the mechanism by which CAV1 expression is lost from host cells, and how this loss leads to progressive disease, could allow a therapy that restores or substitutes for CAV1 activity in stromal cells or that targets the key cytokines involved in this paracrine signalling.