A study initiated by a University of Arizona Comprehensive Cancer Center physician-scientist has for the first time defined how loss of the Y chromosome in male immune cells negatively affects immune system function. The findings, published in Nature, may explain why loss of Y is associated with lower cancer survival rates.
In males, each cell in the body usually contains one X and one Y chromosome. “Loss of Y” is a common, nonhereditary genetic change in men in which an immune cell in the blood loses its Y chromosome. It is often associated with aging. Loss of Y has been linked to increased mortality from carcinomas for many years, though no one knew why.
This study is the first to identify and define the relationship between loss of Y in white blood cells, immune cells and tumours, providing insights as to why men with loss of Y have increased cancer risks and poorer outcomes.
“These findings represent a big step forward in our understanding of why men with loss of Y in their blood cells have a higher mortality from cancer. It turns out it’s because these cells make the immune system infiltrating the cancer less effective,” said Dan Theodorescu, MD, PhD, director of the Cancer Center and a professor in the College of Medicine – Tucson.
“We hope this provides a solid lead and framework for the nascent Y chromosome field to pursue so we can collectively better understand all the possible biological implications of this finding and how to use them to develop more effective approaches in prevention, treatment resulting in higher survival rates for patients.”
The research team discovered that loss of the Y chromosome – previously identified in malignant epithelial cells by the Theodorescu lab – also occurred in nearby noncancerous tissues, including connective tissue and immune cells.
Most notably, the team found that this chromosomal loss in helper and cytotoxic T cells, which are responsible for attacking cancer cells, was associated with a reduced ability to kill those cancerous cells. The findings suggest a mechanism by which tumours may evade immune detection and suppression.
Finally, the research team found that loss of Y in epithelial cells, combined with loss of Y in T cells, resulted in more aggressive cancers and lower survival rates in patients.
“The study has potential implications for current immunotherapies, including CAR T therapy,” Theodorescu said. “Further research is clearly needed but perhaps immunotherapies using cells from a patient’s immune system could be screened for loss of Y before being used in treatment.”
Source: University of Arizona
