By Janis Siegel, Jewish Sound Columnist
The evidence that our sleep time and quality is a significant factor in our health continues to mount.
In May 2014, Israel: to Your Health reported that researchers at the Rambam Medical Campus in Haifa saw the mice in their study published in the Journal of Cancer Research grow larger and more aggressive tumors with intermittent interruptions to their sleep cycles.
Now, in October 2014, research published in the journal Nature Communications, Weizmann Institute of Technology researchers found that one of two cell receptors found in all cells, GR, which manages adrenaline levels under stress, lowered the cell-growing and travel-inducing effect of the other cell receptor, EGF. Every cell has receptor sites for both EGF and GC.
The four-year study that tested mice and looked at cultured human cells is trying to shed more light on the relationship between these cell receptors.
“Our study focused on the molecular mechanism of EGFR-GR interaction,” Dr. Yosef Yarden, Rambam’s Harold and Zeda Goldenberg Chair of Molecular Cell Biology in the Department of Biological Regulation, told The Jewish Sound. “We found that GR activation powerfully restrains EGFR activity, intercepting its signaling at multiple levels. During the ‘human’ daytime, GR activity is high and this might help to decrease EGFR activity.”
Because the proliferation of all cells, including cancer cells, is increased by EGF, the endometrial growth factor, and appears to be lowered by GC, the glucocorticoid factor during the day when its levels in the body are higher, nighttime would be a better time to administer cancer-fighting treatments for the best results, say the researchers.
Yarden’s current study followed previous research that showed GR levels could reduce the effect of EGF on mammary cell migration.
Whether the presence of both EGF and GC might be found at the same levels and in the same circadian rhythm in people who work a nightshift or a graveyard shift was not clear to Yarden.
“Our study is just at the beginning and we will definitely need further studies for proper evaluation of GR-EGFR crosstalk in pathological conditions or in subjects with altered circadian life style, such as the night shift workers,” he said.
In other research, Yarden’s group also found that high levels of GR were associated with positive outcomes for breast cancer.
Because EGFR and other types of cell receptors are known to be associated with the progression of breast cancer, Yarden looked at a data set from more than 2,000 breast cancer tumors from cases in the United Kingdom and Canada as well as two other smaller groups of patients from independent studies.
All of the patients in the data they analyzed were separated into groups of subjects who had similar cancers and who were treated with the same protocol.
The researchers found that all of the patients who had the longest survival rates also had high levels of the glucocorticoid.
When sorted for the stage of their cancer and not the type, the data showed that there was a low survival rate in patients with advanced cancers and all had low GR levels. The patients with less advanced cancers had higher GR levels, suggesting to his team that GR levels decline late in the progression of the cancer.
Because the levels of the adrenal hormone glucocorticoid could be affected by other factors in the body, including stress levels, which could impact its effect on the EGF activity in the cells, it would seem that a patient’s lifestyle and emotional states might also regulate GC levels and impact his or her health.
“This is an important open question in the field,” said Yarden. “For many reasons stress is such a complex mechanism and definitely cortisol is just one of the players. The GCs oscillations are important. As in many physiological conditions, it’s the high-low mechanism that must be preserved in order to ensure a proper function. Any other situation that brings the level either always too high or too low, or that reduce the intensity of the fluctuations, might impair the right activity. Hence we need to further investigation on that direction as well.”
Longtime JTNews correspondent and freelance journalist Janis Siegel has covered international health research for SELF magazine and campaigns for Fred Hutchinson Cancer Research Center.