Asian Pacifc Journal of Cancer Prevention, Vol 15, 2014 4455 DOI:http://dx.doi.org/10.7314/APJCP.2014.15.11.4455 Gene Expression Changes of Serotonin Receptors, 5-HT3AR and 5-HT2AR, in Breast Cancer Patients Asian Pac J Cancer Prev, 15 (11), 4455-4458 Introduction Breast cancer is a serious and potentially lethal disease among 40-50 aged women and its incident rate is one out of eight in the United States and one out of thirty fve people in Asia. Incidence of breast carcinoma is 10 per 100,000 of population with 7000 new cases annually in Iran. The age specifc rate in females is 23.16/100,000. Every year 1200 women die due to breast carcinoma with burden of 0/31 DALY/1000, which is the third in ranking of burden of disease (BOD) among women and seventh rank in both sexes. It is expected that the number of new cases will rise up to 20,000,000 by 2015 globally and 12,000,000 deaths annually 70% of which will occur in developing countries (Akbari et al., 2011; Haghighat et al., 2012). It is a multi-factor disease, genetically mutation and environmental condition plays important role in the breast cancer (Madigan et al., 1995). Only 5-10 percent of the breast cancer patients have a known mutation and about 70% of breast cancer patient are not related to genetically mutation. The breast cancer is 1 Department of Medical Genetics, National Institute of Genetic Engineering and Biotechnology, 2 Department of Psychiatry, Mental Health Research Center, Iran University of Medical Sciences, 3 Department of World Health Organization Collaborating for Mental Health, 4 Cancer Research Center, Shohada Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran *For correspondence: ghah@nigeb.ac.ir Abstract Breast cancer is a serious and potentially lethal multi-factor disease among 40-50 aged women in both developed and developing countries. Also, various studies have pointed to roles of neurotransmitters like serotonin in development of cancers, through action on various types of receptors. This study was conducted to evaluate serotonin receptor (5HT2AR and 5HT3AR) genes expression in peripheral blood mononuclear cells (PBMCs) of breast cancer patients in comparison with the healthy people and in the MCF7 cell line. Peripheral blood samples were obtained from 30 patients and 30 healthy individuals. Total RNA was extracted from PBMCs and MCF-7 cells. and 5HT2AR and 5HT3AR were detected by RT-PCR techniques. Finally, serotonin receptor gene expression variation in breast cancer patients and MCF-7 cells were determined by real time-PCR. This latter indicated signifcant promotion in expression of 5HT3AR and 5HT2AR in PBMCs in breast cancer patients but expression of 5HT2AR in the MCF-7 cell line was signifcantly decreased. In conclusion, after performing complimentary tests, determine of gene expression changes in serotonin receptors (5HT2AR and 5HT3AR) may be useful as a new approach in treatment of breast cancer based on use of antagonists. Keywords: Breast cancer - serotonin receptors - gene expression - real time-PCR RESEARCH ARTICLE Evaluation of Gene Expression Changes of Serotonin Receptors, 5-HT3AR and 5-HT2AR as Main Stress Factors in Breast Cancer Patients Seyed Hesam Hejazi 1 , Ghasem Ahangari 1 *, Majid Pornour 1 , Abdolkhaleagh Deezagi 1 , Saeed Aminzadeh 1 , Hamid Reza Ahmadkhaniha 2, 3 , Mohamad Esmail Akbari 4 commonplace disease between women but 1-2 percent of patients were men and because of their late diagnosis, men have a higher mortality rate (Donegan and Redlich, 1996; Haghighat et al., 2012). Whereas the greatest risk factor for breast cancer are female, ageing parity, and breastfeeding inheritance, but environmental factors are critically important in initiation of disease (Helmrich et al., 1983; Akbari et al., 2011). Environmental factors like stress, can lead to the disruption of the balance of central nervous system and immune system. Relationship between stress and breast cancer development remain controversial (Pinquart and Duberstein, 2010; Antonova et al., 2011). Many researchers believed that mental and psychological conditions have a fundamental role in progression of cancers (Reiche et al., 2004). Interaction and balance of nervous and immune systems are essential for maintaining of homeostasis. There are strong evidence that the CNS, endocrine and immune system talk to each other and this process mediated with neurotransmitters (serotonin, norepinephrine and dopamine), neurohormons (growth hormone and prolactin) and cytokines (interleukin1,