Jina Hong

Differential susceptibility to obesity between male, female and ovariectomized female mice

BackgroundThe prevalence of obesity has increased dramatically. A direct comparison in the predisposition to obesity between males, premenopausal females, and postmenopausal females with various caloric intakes has not been made. To determine the effects of sex and ovarian hormones on the susceptibility to obesity, we conducted laboratory studies with mice. To eliminate confounders that can alter body weight gain, such as age and food consumption; we used mice with the same age and controlled the amount of calories they consumed.MethodsWe determined sex-specific susceptibility to obesity between male, non-ovariectomized female, and ovariectomized female mice. To compare susceptibility to gaining body weight between males and females, animals from each sex were exposed to either a 30% calorie-restricted, low-fat (5% fat), or high-fat (35% fat) diet regimen. To establish the role of ovarian hormones in weight gain, the ovaries were surgically removed from additional female mice, and then were exposed to the diets described above. Percent body fat and percent lean mass in the mice were determined by dual energy x-ray absorptiometry (DEXA).ResultsIn all three diet categories, male mice had a greater propensity of gaining body weight than female mice. However, ovariectomy eliminated the protection of female mice to gaining weight; in fact, ovariectomized female mice mimicked male mice in their susceptibility to weight gain. In summary, results show that male mice are more likely to become obese than female mice and that the protection against obesity in female mice is eliminated by ovariectomy.ConclusionUnderstanding metabolic differences between males and females may allow the discovery of better preventive and treatment strategies for diseases associated with body weight such as cancer and cardiovascular disease.

Oestrogen alters adipocyte biology and protects female mice from adipocyte inflammation and insulin resistance

Aims: Obesity is associated with insulin resistance, liver steatosis and low‐grade inflammation. The role of oestrogen in sex differences in the above co‐morbidities is not fully understood. Our aim was to assess the role oestrogen has in modulating adipocyte size, adipose tissue oxidative stress, inflammation, insulin resistance and liver steatosis.

Effects of body weight and alcohol consumption on insulin sensitivity

BackgroundObesity is a risk factor for the development of insulin resistance, which can eventually lead to type-2 diabetes. Alcohol consumption is a protective factor against insulin resistance, and thus protects against the development of type-2 diabetes. The mechanism by which alcohol protects against the development of type-2 diabetes is not well known. To determine the mechanism by which alcohol improves insulin sensitivity, we fed water or alcohol to lean, control, and obese mice. The aim of this study was to determine whether alcohol consumption and body weights affect overlapping metabolic pathways and to identify specific target genes that are regulated in these pathways.MethodAdipose tissue dysfunction has been associated with the development of type-2 diabetes. We assessed possible gene expression alterations in epididymal white adipose tissue (WAT). We obtained WAT from mice fed a calorie restricted (CR), low fat (LF Control) or high fat (HF) diets and either water or 20% ethanol in the drinking water. We screened the expression of genes related to the regulation of energy homeostasis and insulin regulation using a gene array composed of 384 genes.ResultsObesity induced insulin resistance and calorie restriction and alcohol improved insulin sensitivity. The insulin resistance in obese mice was associated with the increased expression of inflammatory markers Cd68, Il-6 and Il-1α; in contrast, most of these genes were down-regulated in CR mice. Anti-inflammatory factors such as Il-10 and adrenergic beta receptor kinase 1 (Adrbk1) were decreased in obese mice and increased by CR and alcohol. Also, we report a direct correlation between body weight and the expression of the following genes: Kcnj11 (potassium inwardly-rectifying channel, subfamily J, member 11), Lpin2 (lipin2), and Dusp9 (dual-specificity MAP kinase phosphatase 9).ConclusionWe show that alcohol consumption increased insulin sensitivity. Additionally, alterations in insulin sensitivity related with obesity were coupled with alterations in inflammatory genes. We provide evidence that alcohol may improve insulin sensitivity by up-regulating anti-inflammatory genes. Moreover, we have indentified potential gene targets in energy metabolic pathways and signal transducers that may contribute to obesity-related insulin resistance as well as calorie restriction and alcohol-induced insulin sensitivity.

Alcohol promotes breast cancer cell invasion by regulating the Nm23-ITGA5 pathway.

BackgroundAlcohol consumption is an established risk factor for breast cancer metastasis. Yet, the mechanism by which alcohol promotes breast cancer metastases is unknown. The ability of cancer cells to invade through tissue barriers (such as basement membrane and interstitial stroma) is an essential step towards establishing cancer metastasis. In the present study, we identify and examine the roles of two genes, Nm23 and ITGA5, in alcohol-induced breast cancer cell invasion.MethodsHuman breast cancer T47D cells were treated with ethanol at various concentrations. Boyden chamber invasion assays were used to measure cellular invasive ability. The mRNA expression level of metastasis suppressor genes including Nm23 was determined by qRT-PCR. ITGA5 was identified using a qRT-PCR array of 84 genes important for cell-cell and cell-extracellular matrix interactions. Nm23 overexpression in addition to Nm23- and ITGA5 knock-down were used to determine the role of the Nm23-ITGA5 pathway on cellular invasive ability of T47D cells. Protein expression levels were verified by Western blot.ResultsAlcohol increased the invasive ability of human breast cancer T47D cells in a dose-dependent manner through the suppression of the Nm23 metastatic suppressor gene. In turn, Nm23 down-regulation increased expression of fibronectin receptor subunit ITGA5, which subsequently led to increased cellular invasion. Moreover, Nm23 overexpression was effective in suppressing the effects of alcohol on cell invasion. In addition, we show that the effects of alcohol on invasion were also inhibited by knock-down of ITGA5.ConclusionsOur results suggest that the Nm23-ITGA5 pathway plays a critical role in alcohol-induced breast cancer cell invasion. Thus, regulation of this pathway may potentially be used to prevent the establishment of alcohol-promoted metastases in human breast cancers.

Alcohol consumption promotes mammary tumor growth and insulin sensitivity

Epidemiological data show that in women, alcohol has a beneficial effect by increasing insulin sensitivity but also a deleterious effect by increasing breast cancer risk. These effects have not been shown concurrently in an animal model of breast cancer. Our objective is to identify a mouse model of breast cancer whereby alcohol increases insulin sensitivity and promotes mammary tumorigenesis. Our results from the glucose tolerance test and the homeostasis model assessment show that alcohol consumption improved insulin sensitivity. However, alcohol-consuming mice developed larger mammary tumors and developed them earlier than water-consuming mice. In vitro results showed that alcohol exposure increased the invasiveness of breast cancer cells in a dose-dependent manner. Thus, this animal model, an in vitro model of breast cancer, may be used to elucidate the mechanism(s) by which alcohol affects breast cancer.

Exogenous estrogen protects mice from the consequences of obesity and alcohol.

ObjectiveBreast cancer is the second leading cause of cancer death among American women. Risk factors for breast cancer include obesity, alcohol consumption, and estrogen therapy. In the present studies, we determine the simultaneous effects of these three risk factors on wingless int (Wnt)-1 mammary tumor growth. MethodsOvariectomized female mice were fed diets to induce different body weights (calorie restricted, low fat, high fat), provided water or 20% alcohol, implanted with placebo or estrogen pellets and injected with Wnt-1 mouse mammary cancer cells. ResultsOur results show that obesity promoted the growth of Wnt-1 tumors and induced fatty liver. Tumors tended to be larger in alcohol-consuming mice and alcohol exacerbated fatty liver in obese mice. Estrogen treatment promoted weight loss in obese mice, which was associated with the suppression of tumor growth and fatty liver. ConclusionsIn summary, we show that estrogen protects against obesity, which is associated with the inhibition of fatty liver and tumor growth.

Ethanol Consumption Does Not Promote Weight Gain in Female Mice

Background: The prevalence of obese adult women has increased dramatically in the United States. Individuals consuming alcoholic beverages may obtain as much as 6–10% of their calories from ethanol; consequently, ethanol may contribute to a positive energy balance and weight gain in women consuming ethanol. The objective of these studies is to determine if ethanol consumption affects weight gain or body fat levels in female mice. Methods: In order to determine the effects of ethanol consumption on weight gain, female mice were given either water or 20% w/v ethanol in the drinking water; mice were then placed on 1 of 3 diets for 20 weeks: (1) 30% calorie-restricted diet, (2) low-fat diet or (3) high-fat diet. Mice were scanned using a GE Lunar Piximus Densitometer to determine body fat, lean body mass and bone mineral density. Results: Mice consuming the high-fat diet had the highest body weight. Moreover, ovariectomy exacerbated the effects of the high-fat diet. That is, ovariectomized female mice consuming the high-fat diet gained a higher amount of body weight and adipose tissue than nonovariectomized mice consuming the high-fat diet. Ethanol-consuming mice did not have a higher susceptibility to gaining body weight or body fat, even though they tended to have higher caloric intake than water-consuming mice. Conclusions: In female mice that consumed a high-fat diet, chronic ethanol consumption did not increase susceptibility to gaining weight or becoming obese.

P3-09-05: Understanding the Role of Estrogen in Sex Differences in Adipocyte Biology for Cancer Prevention.

Background: Evidence shows that obesity increases the risk and mortality of many cancers, specifically breast cancer in post-menopausal women. Epidemiological studies demonstrate that males are at an increased risk for developing obesity, diabetes, and cancer compared to females, and after menopause, females mimic the males in their susceptibility to the above diseases. Furthermore, it has been established that obesity increases systemic and adipose tissue inflammation and oxidative stress, which is known to augment cancer progression. However, the role of estrogen in regulating these metabolic processes in adipose tissue is unclear; therefore, our objective is to determine the role of estrogen in adipose tissue morphology, inflammation and oxidative stress. Methods: To determine the role of estrogen in gender differences in the susceptibility to obesity we used C57BL/6J mice (15/group): 1) males 2) nonovariectomized females 3) ovariectomized females and 4) ovariectomized females supplemented with estrogen, which were randomized to the following diets: 30% calorie-restricted, low-fat or high-fat diet. We measured weight gain, percent body fat, abdominal adipose tissue, and adipocyte size. Additionally, we assessed markers of adipose tissue inflammation, DNA damage, and oxidative stress. Results: Male mice were more susceptible to obesity than female mice. Removal of the ovaries eliminated the protection to obesity and estrogen supplementation restored this protection in females. In the low-fat and high-fat diet groups, male and ovariectomized female mice gained more abdominal adipose tissue due to increased adipocyte size compared to nonovariectomized female mice and ovariectomized female mice supplemented with estrogen. In the mice consuming the high fat diet, the enlarged adipocytes observed in the male and ovariectomized female mice were accompanied with crownlike structures surrounding necrotic adipocytes and F480 positive macrophages, suggesting macrophage infiltration. To determine if there were sex differences in oxidative stress, we stained adipose tissue with γH2AX. Results suggest that nonovariectomized female mice and ovariectomized female mice supplemented with estrogen have less oxidative stress compared to males and ovariectomized females. Additionally, our results show that nonovariectomized female and ovariectomized female mice supplemented with estrogen had significantly lower CD68, TNFα and iNOS mRNA expression levels, but higher catalase mRNA expression levels. Conclusion: Male mice are more susceptible to the obesogenic effects of high fat diets compared to nonovariectomized female mice. In ovariectomized females, estrogen supplementation has a protective effect against obesity, adipose tissue inflammation and oxidative stress. Our future studies will determine the mechanisms by which estrogen protects female mice from adipose tissue inflammation and oxidative stress, whether it is a direct or indirect effect. Determining the role of estrogen on the above key metabolic processes related to obesity is necessary to develop effective strategies for cancer prevention specifically in post-menopausal females. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-09-05.

Abstract 3268: Alcohol, obesity and estrogen modulate mammary tumor growth through adiposity and angiogenensis

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Alcohol, obesity and estrogen modulate mammary tumor growth through adiposity and angiogenensis Jina Hong, Valerie B. Holcomb, and Nomeli P Nunez Background: Alcohol consumption increases breast cancer risk in women. Postmenopausal women who consume alcohol come in all shapes and sizes, including overweight and obese; some of these women may also take estrogen to prevent the side effects of menopause. It is unclear whether the effects of alcohol on breast cancer development are modified by body weight or exogenous estrogen. In this study, we will determine if the effects alcohol on breast cancer are modified by body weight and exogenous estrogen. Methods: To determine whether the effects of alcohol on mammary cancer are modified by body weight, we injected subcutaneously Met-1 mouse mammary cancer cells to lean, overweight, and obese female mice consuming water or alcohol. Likewise, to determine if the effects of alcohol on mammary tumorigenesis are modified by exogenous estrogen, we implanted estrogen pellets (0.18mg/day or 0.72mg/day) into ovariectomized female mice; subsequently, we injected Met-1 cancer cells into these mice and then measured tumor growth. Results: Results show that alcohol-consuming mice were more insulin sensitive than water-consuming mice; also, alcohol-consuming mice developed earlier and larger tumors than water-consuming mice (p<0.05). Our data show that obese mice developed larger tumors than lean mice. Obese mice had higher levels of insulin, IGF-1, and leptin. The only mammary tumor growth factor that was increased by alcohol consumption was leptin (p<0.05). Additionally, alcohol intake increased the pro-angiogenesis factor VEGF (p<0.05). Conclusion: Results suggest that alcohol consumption, obesity, and estrogen treatment modulate mammary tumorigenesis through adipose tissue and angiogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3268.