“Therefore, understanding the stimuli which promote exosome release by tumour cells is important in understanding tumour development.”
The team investigated how starving breast cancer cells of oxygen (also called hypoxia) impacted the cell’s exosome release.
“As a tumour grows, it rapidly outgrows its blood supply, leaving portions of the tumour with regions where the oxygen concentration is significantly lower than in healthy tissues,” Professor Gleadle said.
“Hypoxic tumour cells are usually resistant to radiotherapy and chemotherapy and often result in the worst patient outcomes, although the reasons behind this remain unclear.”
Looking at three different breast cancer cell lines, the team found that the more the cancer cell was starved of oxygen, the more exosomes it released.
“This may help the cancer cell to promote its own survival and invasion,” Professor Gleadle said.
The research has important implications for how tumour cells might signal to surrounding tissue in order to spread, and could mean that tumours spread more when they are starved of oxygen because of the increase of these invasive exosome signals.
The team also found that the exosomes coming from oxygen-starved cancer cells contained more of a particular cancer-causing microRNA, called miR-210, an important discovery which could one day lead to a blood test that detects rapidly growing tumours.
This research has been enabled from Flinders Medical Centre Foundation funding. Recent funds raised by Blokes for Breast Cancer will allow the team to extend their investigation into how tumours communicate with their environment.