Stress can make tumours grow bigger

A new research suggests that hormones produced during periods of stress accelerate the growth of tumours.

Chronic stress has recently been implicated as a factor that may increase the growth rate of tumours. However, the mechanisms underlying this effect have not been determined.

Now, Anil Sood and colleagues, at the University of Texas MD Anderson Cancer Center, Houston, have generated data using human ovarian cancer cell lines and tumour specimens that indicate that stress hormones, especially norepinephrine and epinephrine, can contribute to tumour progression in patients with ovarian cancer.

The researchers, therefore, suggest that targeting stress hormones and the signaling pathways that they activate might be of benefit to individuals with cancer.

Anoikis is the process by which cells are triggered to die when separated from their surrounding matrix and neighbouring cells.

Tumour cells that spread to other sites somehow escape anoikis. In the study, exposure of human ovarian cancer cells lines to either of the stress hormones norepinephrine or epinephrine protected them from anoikis.

Similarly, in a mouse model of ovarian cancer, restraint stress and the associated increases in norepinephrine and epinephrine protected the tumour cells from anoikis and promoted their growth. This effect was associated with activation of the protein FAK.

The clinical significance of these data was highlighted by the observation that in human ovarian cancer patients, behavioural states related to greater stress hormone activity were associated with higher levels of activated FAK, which was in turn linked to substantially accelerated mortality.