Am J Transl Res 2016;8(4):1659-1677 www.ajtr.org /ISSN:1943-8141/AJTR0025472
Original Article miR-3646 promotes cell proliferation, migration, and invasion via regulating G2/M transition in human breast cancer cells Shuang Tao1, Yao-Bang Liu1, Zhi-Wei Zhou2, Bin Lian1, Hong Li1, Jin-Ping Li1, Shu-Feng Zhou3 Ningxia Medical University, Yinchuan, Ningxia 750004, China; 2Department of Pharmaceutical Sciences, College of Pharmacy, Texas Tech University, Health Sciences Center, Amarillo, Texas, USA; 3Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, Florida, USA
1
Received February 2, 2016; Accepted March 1, 2015; Epub April 15, 2016; Published April 30, 2016 Abstract: MicroRNAs (miRNAs) are small non-coding RNAs that are often located in genomic breakpoint regions and play a critical role in regulating a variety of the cellular processes in human cancer. miR-3646 has been reported to take part in tumorigenic progression in breast and bladder cancer, but its potential functions and exact mechanistic roles in breast cancer are still unclear. The objective of this study was to investigate the role of miR-3646 in breast cancer growth and metastasis using both bioinformatic and experimental approaches. Before starting the bench work, we conducted a bioinformatic study to predict the target genes regulated by miR-3646 using a panel of different algorithms. The results showed that miR-3646 might regulate a large number of genes that are related to cell growth, proliferation, metabolis, transport, and apoptosis and some were cancer-related genes. We found that the expression level of miR-3646 was significantly upregulated in breast cancer cells and tissues compared with normal breast cells and no tumor tissues. Subsequently, the MTT and colony formation assay results showed that up-regulation of miR-3646 promoted the cell viability and proliferation. Our results also showed that down-regulation of miR-3646 arrested the cells in G2/M phase in MCF7 and MDA-MB-231 cells which was accompanied by the down-regulation of CDK1/CDC2 and cyclin B1 and upregulation of p21Waf1/Cip1, p27 Kip1, and p53, suggesting that down-regulation of miR-3646 induces G2/M arrest through activation of the p53/p21/CDC2/cyclin B1 pathway. In addition, overexpression of miR-3646 promoted migration and invasion of MCF7 and MDA-MB-231 cells. Taken together, miR-3646 is a potential oncogene in breast cancer and it may represent a new niomarker in the diagnosis and prediction of prognosis and therapeutic response. Keywords: miR-3646, breast cancer, proliferation, migration, invasion, bioinformatics
Introduction Breast cancer is the second most common cancer with nearly 1.67 million new cases diagnosed in 2012 and the most common cause of cancer-related mortality among females with over 508,000 deaths due to breast cancer worldwide [1, 2]. It represents about 12% of all new cancer cases and 25% of all cancers in women. In 2015, it was estimated that among American women there would be 231,840 new cases of invasive breast cancer and 40,290 breast cancer deaths. Incidence rates of breast cancer vary greatly worldwide from 19.3 per 100,000 women in Eastern Africa to 89.7 per
100,000 women in Western Europe. In the past two decades, China experienced an everincreasing incidence of breast cancer, twice as fast as global rates [3]. According to the latest Chinese Cancer Registry Annual Report, breast cancer has become the most common cancer among Chinese women and ranked the 5th leading cause of cancer-related deaths [4]. Breast cancer survival rates vary greatly worldwide, ranging from 80% or over in North America, Sweden and Japan to around 60% in middle-income countries and below 40% in lowincome countries. A familial history of breast cancer increases the risk by a factor of two or three. Some mutations, particularly in BRCA1,
miR-3646 and breast cancer BRCA2 and p53 result in a very high risk for breast cancer. Reproductive factors associated with prolonged exposure to endogenous estrogens, such as early menarche, late menopause, late age at first childbirth are among the most important risk factors for breast cancer. Exogenous hormones also exert a higher risk for breast cancer. Oral contraceptive and hormone replacement therapy users are at higher risk than non-users. Breast cancer can be treated by surgery, chemotherapy, radiotherapy, and immunotherapy. As a result of regular mammography screening programs, a shift toward the detection of early-stage (
Original Article miR-3646 promotes cell proliferation, migration, and invasion via regulating G2/M transition in human breast cancer cells Shuang Tao1, Yao-Bang Liu1, Zhi-Wei Zhou2, Bin Lian1, Hong Li1, Jin-Ping Li1, Shu-Feng Zhou3 Ningxia Medical University, Yinchuan, Ningxia 750004, China; 2Department of Pharmaceutical Sciences, College of Pharmacy, Texas Tech University, Health Sciences Center, Amarillo, Texas, USA; 3Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, Florida, USA
1
Received February 2, 2016; Accepted March 1, 2015; Epub April 15, 2016; Published April 30, 2016 Abstract: MicroRNAs (miRNAs) are small non-coding RNAs that are often located in genomic breakpoint regions and play a critical role in regulating a variety of the cellular processes in human cancer. miR-3646 has been reported to take part in tumorigenic progression in breast and bladder cancer, but its potential functions and exact mechanistic roles in breast cancer are still unclear. The objective of this study was to investigate the role of miR-3646 in breast cancer growth and metastasis using both bioinformatic and experimental approaches. Before starting the bench work, we conducted a bioinformatic study to predict the target genes regulated by miR-3646 using a panel of different algorithms. The results showed that miR-3646 might regulate a large number of genes that are related to cell growth, proliferation, metabolis, transport, and apoptosis and some were cancer-related genes. We found that the expression level of miR-3646 was significantly upregulated in breast cancer cells and tissues compared with normal breast cells and no tumor tissues. Subsequently, the MTT and colony formation assay results showed that up-regulation of miR-3646 promoted the cell viability and proliferation. Our results also showed that down-regulation of miR-3646 arrested the cells in G2/M phase in MCF7 and MDA-MB-231 cells which was accompanied by the down-regulation of CDK1/CDC2 and cyclin B1 and upregulation of p21Waf1/Cip1, p27 Kip1, and p53, suggesting that down-regulation of miR-3646 induces G2/M arrest through activation of the p53/p21/CDC2/cyclin B1 pathway. In addition, overexpression of miR-3646 promoted migration and invasion of MCF7 and MDA-MB-231 cells. Taken together, miR-3646 is a potential oncogene in breast cancer and it may represent a new niomarker in the diagnosis and prediction of prognosis and therapeutic response. Keywords: miR-3646, breast cancer, proliferation, migration, invasion, bioinformatics
Introduction Breast cancer is the second most common cancer with nearly 1.67 million new cases diagnosed in 2012 and the most common cause of cancer-related mortality among females with over 508,000 deaths due to breast cancer worldwide [1, 2]. It represents about 12% of all new cancer cases and 25% of all cancers in women. In 2015, it was estimated that among American women there would be 231,840 new cases of invasive breast cancer and 40,290 breast cancer deaths. Incidence rates of breast cancer vary greatly worldwide from 19.3 per 100,000 women in Eastern Africa to 89.7 per
100,000 women in Western Europe. In the past two decades, China experienced an everincreasing incidence of breast cancer, twice as fast as global rates [3]. According to the latest Chinese Cancer Registry Annual Report, breast cancer has become the most common cancer among Chinese women and ranked the 5th leading cause of cancer-related deaths [4]. Breast cancer survival rates vary greatly worldwide, ranging from 80% or over in North America, Sweden and Japan to around 60% in middle-income countries and below 40% in lowincome countries. A familial history of breast cancer increases the risk by a factor of two or three. Some mutations, particularly in BRCA1,
miR-3646 and breast cancer BRCA2 and p53 result in a very high risk for breast cancer. Reproductive factors associated with prolonged exposure to endogenous estrogens, such as early menarche, late menopause, late age at first childbirth are among the most important risk factors for breast cancer. Exogenous hormones also exert a higher risk for breast cancer. Oral contraceptive and hormone replacement therapy users are at higher risk than non-users. Breast cancer can be treated by surgery, chemotherapy, radiotherapy, and immunotherapy. As a result of regular mammography screening programs, a shift toward the detection of early-stage (
