PHILADELPHIA — Social environment can play an important role in the biology of disease, including breast cancer, and lead to significant differences in health outcome, according to results of a study published in Cancer Prevention Research, a journal of the American Association for Cancer Research.
“This study uses an elegant preclinical model and shows that social isolation alters expression of genes important in mammary gland tumor growth,” said the journal’s Deputy Editor Caryn Lerman, Ph.D. “It further elucidates the molecular mechanisms linking environmental stress with breast cancer development and progression.”
These findings suggest novel targets for chemoprevention, and future studies should evaluate whether these molecular processes can be reversed by chemopreventive agents, according to Lerman, who is the Mary W. Calkins professor of psychiatry and scientific director of the Abramson Cancer Center at the University of Pennsylvania, Philadelphia.
Previous results from clinical studies have indicated that social support can improve the health outcome of patients with breast cancer. Epidemiological studies have suggested that social isolation increases the mortality risk from several chronic diseases.
Suzanne D. Conzen, M.D., associate professor in the department of medicine and the Ben May department for cancer research at the University of Chicago, along with colleagues from the Institute of Mind and Biology at the University of Chicago, evaluated whether an unfavorable social environment could influence tumor growth in mice that are genetically predisposed to mammary gland cancer.
They found that female mice that were chronically stressed because of social isolation (from the time they were first separated from their mothers) developed significantly larger mammary gland tumors compared to those mice that were group-housed.
Additionally, the isolated mice developed a heightened corticosterone stress hormone response.
“Despite the genetic similarity of the mice assigned to grouped versus isolated housing, living in the stressful environment was associated with greater tumor size, suggesting that the social environment may in fact alter the biology of cancer growth?then, of course, the question becomes how,” she said.
The researchers studied gene expression in the mouse mammary tissues and found that alterations in the expression levels of metabolic pathway genes, which are expected to favor increased tumor growth, had occurred in the isolated mice even before tumor size differences were measurable. These gene expression patterns suggest potential molecular biomarkers and/or targets for preventive intervention in breast cancer.
Further research is needed to focus on which specific cell types the changes in gene expression are taking place, according to Conzen. This knowledge could potentially lead to interventions that block similar pathways favoring the growth of human breast cancer.
“Given the increased knowledge of the human genome we can begin to objectively identify and dissect the specific alterations that take place in cancer-prone tissues of individuals in at-risk environments and that will help us to better understand and implement cancer prevention strategies,” she concluded.
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The following leading scientists will address this exciting new research:
Scott M. Lippman, M.D.
Professor and Chair
Department of Thoracic/Head and Neck Medical Oncology
University of Texas M. D. Anderson Cancer Center
Editor-in-Chief
Cancer Prevention Research
Thea Tlsty, Ph.D.
Professor of Pathology
Director, Center for Translational Research in the Molecular Genetics of Cancer
Director, Program of Cell Cycling and Signaling
University of California San Francisco
Caryn Lerman, Ph.D.
Mary W. Calkins Professor
Department of Psychiatry
Scientific Director
Abramson Cancer Center
University of Pennsylvania
Suzanne D. Conzen, M.D.
Associate Professor in the Department of Medicine
Ben May Department for Cancer Research
The University of Chicago
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world’s oldest and largest professional organization dedicated to advancing cancer research. The membership includes 30,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and nearly 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants, research fellowship and career development awards. The AACR Annual Meeting attracts more than 16,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes six major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.
