Low Oxygen conditions help breast cancer cells spread

The scientists have discovered that low oxygen conditions inside the tumors initiate a molecular chain of events that give breast cancer cells their ability to move.

A study by the Johns Hopkins University underlines the importance of hypoxia-inducible factors in promoting breast cancer metastasis.

“High levels of RhoA and ROCKI were known to worsen outcomes for breast cancer patients by endowing cancer cells with the ability to move, but the trigger for their production was a mystery,” said Gregg Semenza, senior author of the study.

“It is known that the production of these proteins increases dramatically when breast cancer cells are exposed to low oxygen conditions,” Semenza said.

In order to move, the cancer cells must make many changes to their internal structures. A thin, parallel filaments form throughout the cells, allowing them to contract and cellular “hands” arise, allowing cells to “grab” external surfaces to pull themselves along. The proteins RhoA and ROCKI are known to be central to the formation of these structures.

Moreover, the genes that code for RhoA and ROCKI were known to be turned on at high levels in human cells from metastatic breast cancers.

In few cases, those increased levels could be traced back to genetic error in protein that controls them, but not in most. This activity led them search for another cause for their high levels.

The study also found that low oxygen conditions, which are frequently present in breast cancer, serve as the trigger to increase the production of RhoA and ROCKI through the action of hypoxia-inducible factors.