The Role of Fat in Tumor Formation

描述（由申请人提供）：肥胖是一个全球性的公共卫生问题。据估计，68%的美国成年人超重或肥胖，造成了严重的发病率和死亡率。最近的研究表明，肥胖会影响患癌症的风险。然而，肥胖引起的分子变化实际上促进了癌症的发展，人们对其知之甚少。早期研究表明，给小鼠喂食高脂肪饮食会增强紫外线B （UVB）诱导的皮肤癌，而通过运动或切除脂肪来减少参数脂肪（子宫周围的腹部脂肪）会减弱紫外线B诱导的皮肤肿瘤形成8,9。因此，我们建立了一个模型，通过软琼脂中jb6p +细胞（一种初始化的小鼠表皮细胞系）的生长来评估脂肪在表皮皮肤细胞转化中的作用。JB6 P+模型是肿瘤启动子（如12- o - tetradecanoylphorol -13-acetate）对肿瘤转化反应的良好表征模型，具有较低的自发转化背景。初步数据表明，从高脂饮食小鼠中分离的参数脂肪可引起jb6p +细胞的转化。低脂饲料小鼠的参数脂肪转化活性明显降低。参数脂肪含有许多有可能刺激细胞增殖的脂肪因子，

DESCRIPTION (provided by applicant): Obesity is a world-wide public health concern. It has been estimated that 68% of American adults are overweight or obese, causing significant morbidity and mortality1. Recent research suggests that obesity can influence cancer risk. However, the molecular changes induced by obesity that actually enhance cancer development are poorly understood2-4. Early research demonstrated that feeding a high fat diet to mice enhanced ultraviolet B (UVB)-induced skin cancer and that reducing parametrial fat (abdominal fat around the uterus) by either exercise or lipectomy attenuated UVB-induced skin tumor formation8,9. This led us to establish a model to evaluate the role of fat in epidermal skin cell transformation as measured by JB6 P+ cell (an initiated mouse epidermal cell line) growth in soft agar. The JB6 P+ model is a well-characterized model for a neoplastic transformation response to tumor promoters such as 12-O-tetradecanoylphorbol-13-acetate and has a low background of spontaneous transformation. Preliminary data demonstrated that parametrial fat isolated from mice fed a high fat diet caused transformation of JB6 P+ cells. Significantly lower transforming activity was observed with parametrial fat from mice fed a low fat chow diet. Parametrial fat contains a number of adipokines that have the potential to stimulate proliferation, inhibit apoptosis and induce cells to produce reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are hallmark characteristics of tumor promoters. A number of these adipokines that have the potential to stimulate transformation were identified in the parametrial fat pads of mice fed a high fat diet. These adipokines were either absent or present in lower abundance in the parametrial fat pads of mice fed a low fat diet and in other fat depots (inguinal, retroperitoneal, subcutaneous). It is our contention that fat in obesity is intrinsicall different from fat from normal subjects in its profile of adipokine production. The central hypothesis of this application is that adipose tissue, specifically parametrial fat, can transform initiated epidermal cells and stimulate carcinogenesis through the release of Serpin E1, TIMP-1 and other adipokines that stimulate reactive oxygen/nitrogen species. The goals of this proposed research are to 1) further characterize a model of fat-stimulated neoplastic transformation 2) determine if the number of calories from fat and the duration of feeding a high fat diet will influence JB6 P+ and HaCaT cell transformation 3) determine the mechanisms of parametrial fat-stimulated transformation both in vitro and in an in vivo model of UVB-induced carcinogenesis and 4) determine if human adipose tissue isolated from obese and normal subjects will stimulate cell transformation. The studies within this proposal will help define the role of fat in skin tumor formation, identify molecular biomarkers of risk and pave the way for future mechanistic work.