Breast cancer is one of the most prevalent cancers in women contributing to cancer-related death in the advanced world. Apart from the menopausal status, the trigger for developing breast cancer may vary widely from race to lifestyle factors. Epidemiological studies refer to obesity-associated metabolic changes as a critical risk factor behind the progression of breast cancer. The plethora of signals arising due to obesity-induced changes in adipocytes present in breast tumor microenvironment, significantly affect the behavior of adjacent breast cells. Adipocytes from white adipose tissue are currently recognized as an active endocrine organ secreting different bioactive compounds. However, due to excess energy intake and increased fat accumulation, there are morphological followed by secretory changes in adipocytes, which make the breast microenvironment proinflammatory. This proinflammatory milieu not only increases the risk of breast cancer development through hormone conversion, but it also plays a role in breast cancer progression through the activation of effector proteins responsible for the biological phenomenon of metastasis. The aim of this review is to present a comprehensive picture of the complex biology of obesity-induced changes in white adipocytes and demonstrate the relationship between obesity and breast cancer progression to metastasis.

The increasing prevalence of obesity has prompted intensive research into understanding its role in pathogenesis and designing appropriate treatments. To determine the signals generated from the interaction of fat cells with a target organ, a reliable white adipocyte model in vitro is needed. Differentiated fibroblasts are the most extensively studied using in vitro cell models of white adipocytes. However, it can be argued that differentiated fibroblasts minimally recapitulate the consequences of obesity. Here, we describe 3T3-L1 MBX cells as a culture model for studying obese adipocytes and their effects. Differentiation of 3T3-L1 MBX cells was at first optimized and then maintained in the presence of fatty acids cocktail combination to induce the obese condition. Lipid accumulation and adipokine secretion profiles were analyzed. Results showed that fatty acid-maintained, differentiated 3T3-L1 MBX cells had significantly greater accumulation of lipids and significant changes in the adipokine secretions in comparison to differentiated 3T3-L1 MBX cells maintained in medium without fatty acids. To elucidate the molecular changes associated with adipogenesis and lipid accumulation profile of 3T3-L1 MBX cells, we have also explored the expression of some of the regulatory proteins related to the development and maintenance of adipocytes from the preadipocyte lineage.

Obesity-associated perturbations in the normal secretion of adipocytokines from white adipocytes can drive the metastatic progression of cancer. However, the association between obesity-induced changes in secretory factors of white adipocytes and subsequent transactivation of the downstream effector proteins impacting metastasis in breast cancer cells remains unclear. Focal adhesion kinase, a cytoplasmic signal transducer, regulates the biological phenomenon of metastasis by activating downstream targets such as beta-catenin and MMP9. Thus, the possible role of phosphorylated FAK in potentiating cancer cell migration was investigated. To elucidate this potential relationship, MCF7 (ER+), MDA-MB-231 (Triple Negative) breast cancer cells, and MCF-10A non-tumorigenic breast cells were exposed to in vitro murine adipocyte-conditioned medium derived from 3T3-L1 MBX cells differentiated to obesity with fatty acid supplementation. Our results show that the conditioned medium derived from these obese adipocytes enhanced motility and invasiveness of breast cancer cells. Importantly, no such changes were observed in the non-tumorigenic breast cells. Our results also show that increased FAK autophosphorylation was followed by increased expression of beta-catenin and MMP9 in the breast cancer cells when exposed to obese adipocyte-conditioned medium, but not in the MCF10A cells. These results indicate that adipocyte-derived secretory factors induced FAK activation through phosphorylation. This in turn increased breast cancer cell migration and invasion by activating its downstream effector proteins beta-catenin and MMP9.

(1) Background: Overconsumption of processed meats, fats, and carbohydrates drives the obesity epidemic in the USA. Associated with this epidemic are increases in metabolic diseases, such as type 2 diabetes, cardiovascular disease, and cancer. In this study, protein levels of adipocytokines isolated from visceral fat in mice fed high-fat diets with proteins modified through ammonium supplementation were analyzed to determine changes that occur as a result of dietary protein source and its modification based on age or sex. (2) Methods: Male and female C3H/HeJ mice were randomized into six customized diets—Group 1: CCN = Control Chow (CC) + Ammonium Hydroxide Enhancement (AHE); Group 2: CC = Control Chow; Group 3: HFBN = High Fat (HF) AHE Dietary Beef; Group 4: HFB = HF Beef; Group 5: HFCN = HF AHE Dietary Casein; Group 6: HFC = HF Dietary Casein. Mice were censored at six-month intervals, and visceral fat was collected for analysis. This study highlights sex- and age-related changes in cellular adipocytokine protein expression from 12 to 18 months. (3) Results: When compared to dietary casein, dietary-beef-fed mice showed increased expression of adiponectin, leptin, and MCP-1. In dietary casein protein diets, high fat content was correlated with the expression of pro-inflammatory adipocytokines leptin, MCP-1, resistin, VEGF-A, and TIMP-1. Sex-related differences were observed in adiponectin, leptin, and MCP-1 expression levels. AHE of dietary protein decreased the expression of adiponectin, leptin, MCP-1, and TIMP-1. Age-related changes in expression were observed in leptin, MCP-1, and VEGF-A. (4) Conclusions: Our results indicate that the source of dietary protein plays a critical role in determining adipocytokine expression in WAT. Furthermore, this study shows that in addition to dietary protein type (beef or casein), AHE and fat content also impact the relative expression of both pro-inflammatory and anti-inflammatory adipocytokines based on sex over time, with leptin and MCP-1 identified as the most frequently affected.

The excess consumption of a high-fat diet has been identified as one of the factors contributing to obesity. Women are at higher risk of adult obesity than men, predisposing them to a different set of detrimental disease conditions. Furthermore, aging studies show that physiological decline also has a serious impact on changes in the endocrine properties of white adipose tissue. However, there is still relatively little known about the factors associated with obesity and aging and their compounding impacts on women’s health. To investigate changes in adipocytokine secretion profiles, obesity was induced in female C3H/HeJ mice through the long-term consumption of a high-fat diet. Weight gain measurements and the Echo MRI analysis of fat composition showed that increases were due solely to the high fat content in the diet. Adipocytokine secretions were analyzed in media conditioned from harvested visceral fat tissue that was organ-cultured ex vivo. Adipocytokine analysis performed across diets and ages showed that there were significant increases in Adiponectin and Leptin secretion in high-fat diets, accelerating increases in Resistin secretion in high-fat diets. Aging induced the increased secretion of Lipcalin-2, Pentraxin-3, Serpin E1, MCP-1, and ICAM-1, regardless of diet. Furthermore, the comparisons of organoid-cultured protein secretions and flash-frozen tissue samples differed greatly, suggesting the WAT organoid cultures may yield information that is more reflective of in situ conditions. Taken together, our results show that high-fat diets and aging in C3H/HeJ female mice significantly impact secretions from adipose tissue, which may contribute to women’s health issues.