In conclusion the partial sequencing and characterization of
In conclusion, the partial sequencing and characterization of R. quelen cyp19a1b provides essential information about this gene and its presence in peripheral tissues outside of the central nervous system in a teleost. Furthermore, we covered sex differences in the effects of E2 on the cyp19a1b gene expression in R. quelen.
Acknowledgements Funding for a research exchange (HCSA) to Canada from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) and the support of the University of Ottawa Research Chair in Neuroendocrinology (VLT) is also acknowledged with appreciation.
Overview Breast cancer is the most frequent cancer among women worldwide with more than 1.6 million new cases detected each year (Torre et al., 2015). This represents about 25% of all diagnosed cancers in women, suggesting that of every four women across the globe who are diagnosed with any type of cancer, one is a case of breast cancer (Torre et al, 2015, Jemal et al, 2011). Although better therapeutic options have allowed important improvements in prognosis over the past 20 years, breast cancer remains one of the most common causes of cancer death among women, translating into 522,000 women who have died from breast cancer in 2012, according to GLOBOCAN 2012 (Ferlay et al., 2015). Clinical and epidemiological studies have identified many important breast cancer risk factors. Some of these factors are intangible or beyond our control; such as age or family history (Jatoi and Benson, 2016). However, several modifiable lifestyle factors have been associated with a higher risk of developing breast cancer. Being overweight or obese is now recognized to be one these risk factors (De Pergola and Silvestris, 2013). Obesity is defined conventionally as a body mass index (BMI) at or above 30 kg/m2 and is characterized by a chronic positive Lithocholic Acid balance that results in an excess accumulation of body fat (Fletcher, 2014). Obesity is a growing global health problem all over the world. The prevalence of obesity has been increasing globally over the past decades, resulting today in over 600 million adults worldwide with a BMI of 30 kg/m2 or greater (Finucane et al, 2011, Stevens et al, 2012). By 2030, the number of overweight and obese adults is projected to reach 2.16 and 1.12 billion, respectively, accounting for 57.8% of the world's adult population (Kelly et al., 2008). The association between obesity and breast cancer risk is complex and can be different depending on menopausal status (Rose and Vona-Davis, 2010), the use of postmenopausal therapy (Munsell et al., 2014), breast cancer subtype (Suzuki et al., 2009) and racial/ethnic group (Bandera et al., 2015). However, there is abundant and consistent epidemiological evidence suggesting that obesity is associated with a higher risk of developing breast cancer in postmenopausal women (Munsell et al, 2014, Renehan et al, 2008, Wiseman, 2008). A meta-analysis of 34 cohort studies including over 2.5 million women reported that each 5 kg/m2 increase in BMI was associated with a 12% increased relative risk of postmenopausal breast cancer (Renehan et al., 2008). It has also been reported that about 50% of breast cancer patients are overweight or obese at diagnosis, further highlighting the close relationship between these two pathologies (Demark-Wahnefried et al., 1997). Importantly, the vast majority of studies linking obesity and breast cancer risk have been conducted in Europe or North America on non-Hispanic White women (Sexton et al., 2011). For this reason, the association between BMI and breast cancer in minorities such as Hispanic and African American women is not well understood and reported observations are inconsistent (Sexton et al., 2011). Additional studies are needed to provide more understanding of the role of obesity in breast cancer development in these minorities and to explain the disparities observed among ethnicities. Obesity is not only a risk factor of breast cancer, it is also a prognostic factor linked to the outcomes of the disease. Obese women with breast cancer are more likely to have larger tumors, advanced disease stage at diagnosis, higher rates of metastasis and to develop endocrine therapy resistance (Santa-Maria et al, 2015, Chan and Norat, 2015). This is supported by clinical trials observing that obese breast cancer patients receiving aromatase inhibitors or chemotherapy show a significantly greater risk of recurrence and a reduced response to treatment in comparison to lean women (Sestak et al, 2010, Folkerd et al, 2012, Karatas et al, 2017). Furthermore, breast cancer specific mortality risk increases in both pre- and postmenopausal obese women compared with normal weight women (Chan et al, 2014, Jiralerspong et al, 2013).