PHILADELPHIA - A study published in Cancer Research, a journal of the American Association for Cancer Research, suggests a possible role for nicotine in breast tumor development and metastases.
The study, conducted by researchers at the Beth Israel Deaconess Medical Center, is among the first to explore the effects of nicotine on mammary cells.
"Although numerous studies indicate the role of nicotine exposure in tumor promotion, little is known about the effect of nicotine on breast tumor development, especially on the metastatic process of breast cancer," said lead author Chang Yan Chen, Ph.D., M.D., at Beth Israel Deaconess Medical Center.
Through a series of in vitro tests Chen and her team of researchers determined that breast epithelial-like MCF10A cells and cancerous MCF7 cells both express several subunits of nAChR (nicotine receptor), that when bound, initiate a signaling process, potentially increasing cell growth and migration.
"The best known role of nAChR is in the nerve system," Chen said. "Although cells from various tissue origins express different subunits of nAChR, we know very little about the functions of nAChR in non-neuronal cells and tissues, in particular in mammary cells."
"We were able to determine that mammary cells express different subunits of nAChR and that nicotine, possibly through perturbing cell cycle checkpoints, potentiates tumorigenesis in mammary cancer-prone or cancer cells," Chen said.
In vivo studies confirmed these findings. When injected into the tail of a mouse the cancerous MCF7 cells migrated to the lungs.
From in vivo and in vitro studies, it indicates that nicotine is not a conventional carcinogen, but rather it combines with other yet to be determined factors to enable tumorigenesis.
"In vitro and in vivo tests showed that no metastasis occurs when the administration of nicotine alone," said Chen. "At this point we can only suggest that nicotine potentiates the growth-related process."
Chen hopes to conduct more studies, in particular under the genetic backgrounds with loss or defect of different tumor suppressors, to further explore the effects of nicotine in relation to first- and second-hand exposure, on breast cancer initiation and development.
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 more than 28,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and 80 other countries. 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. The AACR Annual Meeting attracts more than 17,000 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. AACR publishes five major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. Its most recent publication and its sixth major journal, Cancer Prevention Research, is dedicated exclusively to cancer prevention, from preclinical research to clinical trials. 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.