April 2014, Vol. 8, No. 4, pp. 316-321 Journal of Life Sciences, ISSN 1934-7391, USA RASSF1A Promoter Hypermethylation as a Prognosis and Diagnosis for Breast Cancer in Vietnamese Population Truong Kim Phuong 1 , Lao Duc Thuan 1 , Doan Thi Phuong Thao 2 and Le Huyen Ai Thuy 1 1. Falculty of Biotechnology, Ho Chi Minh City Open University, Ho Chi Minh City 70000, Vietnam 2. Falculty of Medicine, Ho Chi Minh City Medical University, Ho Chi Minh City 70000, Vietnam Received: February 20, 2014 / Accepted: April 8, 2014 / Published: April 30, 2014 Abstract: Aberrant tumor suppressor gene promoter methylation was associated with the several cancers, including breast cancer, which was the common female deaths in most countries involved in Vietnam. The methylation in tumor suppressor genes, including RASSF1A, were the key targets of establishing the potential biomarkers for prognosis and early diagnosis of breast cancer. In present study, with the aim towards using the hypermethylation at CpG islands of promoter of RASSF1A as the biomarker for breast cancer in Vietnamese population, MSP (methyl specific PCR) was carried out to analyze the hypermethylation status of RASSF1A gene in 115 samples including 95 breast cancer specimens and 20 normal breast tissues from another disease (not breast cancer). All samples were obtained from Ho Chi Minh City Medical Hospital, Vietnam. The known predictive and prognostic factors: HER2/neu overexpression was immunohistochemistry stained as input value for breast cancer specimens. For input value confirmed, the overexpression of p53 protein was also analyzed together with prior immunochemical assay. The results indicated that the hypermethylation of frequencies for methylation of given gene reached 42.1% (P < 0.05). In addition, the DNA hypermethylation of RASSF1A gene increased the possibility to be breast cancer with high incidence via calculated of odd ratio (P < 0.05). In conclusion, the hypermethylation of candidate genes could be used as the promising biomarkers applying in Vietnamese breast cancer patients. Key words: RASSF1A, hypermethylation, MSP, bisulfite modification, breast cancer. 1. Introduction Breast cancer was the common cause of death among women in most countries worldwide, counting for 1.6% of female deaths every year with rapidly increases in the developing countries. Vietnam breast cancer incident has increased from a crude rate of 13.8 per 100,000 women in 2000 to 28.1 per 100,000 women in 2010, with an estimated 12,533 breast cancer cases [1]. Among many causes leading to breast cancer, DNA hypermethylation, the common changes of epigenetics events, was considered as the important role in tumorgenesis [2-4]. The tumor suppressor gene, RASSF1A, was silenced by the DNA Corresponding author: Le Huyen Ai Thuy, Ph.D., associate professor, research field: epigenetics. E-mail: lhathuy@gmail.com. hypermethylation has been defined frequently in breast cancer [4, 5]. RASSF1A (RAS association domain family protein 1A), identified at 3q21.3, was an isoform, encoded by RASSF1, which were derived from alternative mRNA splicing and promoter usage and suggested as tumor suppressor gene whose inactivation was implicated in the development of many human cancer, including breast cancer [2, 3]. It was reported that methylation associated inactivation of RASSF1A was also observed in a considerable proportion of breast cancer [4, 5]. Moreover, aberrant RASSF1A promoter hypermethylation has been correlated with the clinicopathological characteristics, including ER, pR, tumor size etc. [4]. Moreover, according to Terada et al. [6], in the case of breast cancer, the amplification D DAVID PUBLISHING