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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biological markers associated with in situ carcinoma and atypical intraductal hyperplasia in the breast are examined to help in identifying a subgroup of premalignant lesions whose natural history may be influenced by epigenetic factors. The biomarkers may be used as indices in clinical trials aiming to assess the effect of weight reduction, dietary intervention or hormone replacement therapy on the risk of progression to invasive breast cancer. In the current state of knowledge, the expression of oestrogen receptors, p53, bcl-2 and HER-2 neu oncogenes and the Ki-67 index of proliferative activity, are the most useful biomarkers for this purpose. In situ carcinoma of the breast manifests a variety of morphological phenotypes with specific biological characteristics. There is evidence that only a proportion of premalignant lesions are committed to progression to invasive cancer while other lesions undergo spontaneous regression at the time of the menopause. Cross-cultural studies suggest that it is the late-stage epigenetic promoting factors which are responsible for the high incidence of postmenopausal breast cancer in Western women. Obesity in middle life and the Western diet favour the development of hyperinsulinaemic insulin resistance, and the metabolic-endocrine effects of its concomitants may promote mammary carcinogenesis around the time of the menopause and increase the incidence of invasive cancer after the menopause. Because biomarker changes in premalignant lesions are nearer in time to these promoting influences, they could provide intermediate endpoints for testing the hypothesis.
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PMID:Premalignant breast lesions: role for biological markers in predicting progression to cancer. 1050 26

Breast and ovarian cancers are the second and fifth leading causes of cancer death, respectively, among women in the United States. Individuals with breast cancer have a 20--30% chance of having at least one relative with the disease. However, only 5--10% of the cases are a direct result of germline mutations in highly penetrable genes, such as BRCA1 and BRCA2 (BRCA1/2) as well as genes TP53 and PTEN. Since 1996, genetic testing for these mutations has been clinically available. A strategy for the management of women at increased familial risk of breast and ovarian cancers is described, which includes genetic assessment, chemoprevention, radiologic screening, and clinical and self-examination. Genetic testing should occur within a cancer genetic clinic after genetic counseling. A blood sample allows determination of the presence of the BRCA1 and BRCA2 genes, the TP53 gene, the PTEN gene, and the ATM gene. Tumor examination has identified a growth factor receptor gene, human epidermal growth factor receptor (HER-2). With regard to diet and lifestyle, women at increased risk of breast cancer could be advised to reduce dietary fat, avoid obesity, decrease alcohol consumption, and take regular exercise. Although chemoprotection is a valuable consideration, it is important to emphasize that the use of Tamoxifen in BRCA1 and BRCA2 mutation carriers is not established, nor is the optimum duration of benefit. An overview of the main outcomes of the current published studies confirms a 38% decrease in breast cancer incidence with Tamoxifen but recommends its use be restricted to women at high risk of breast cancer and low risk for potential side effects. The role of bilateral risk-reducing mastectomy or prophylactic mastectomy has been controversial for several reasons, including the psychosocial significance of the breast in Western cultures, the wide acceptance of breast conservation in surgery for early breast cancer, and the previous lack of data on its efficacy. The surgical procedure should aim to remove substantially all at-risk breast tissue. However, there is a balance between reduction of cancer risk and cosmetic outcome. Bilateral prophylactic oophorectomy can significantly decrease ovarian cancer risk in women who carry BCRA1 mutations. Oophorectomy lowers the risk of breast cancer, even in women who have previously used hormone replacement therapy. There are no published randomized controlled trials examining the effectiveness of mammographic screening in women under 50 years of age with a family history of breast cancer. However, the published studies do suggest that mammographic screening of a high-risk group of women under 50 years of age may detect cancer at a rate equivalent to that seen in women 10 years older with normal risk. Other initial studies also support MRI as having a greater sensitivity than mammography in high-risk women. Breast clinical and self-examination is often advocated, but its effectiveness is unproved, and only one randomized study has been undertaken in women at risk. On the basis of this study as well as one nonrandomized study, it can be concluded that clinical examination as well as mammography are essential in detecting breast cancer. under 50 years of age with a family history of breast cancer. However, the published studies do suggest that mammographic screening of a high-risk group of women under 50 years of age may detect cancer at a rate equivalent to that seen in women 10 years older with normal risk. Other initial studies also support MRI as having a greater sensitivity than mammography in high-risk women. Breast clinical and self-examination is often advocated, but its effectiveness is unproved, and only one randomized study has been undertaken in women at risk. On the basis of this study as well as one nonrandomized study, it can be concluded that clinical examination as well as mammography are essential in detecting breast cancer.
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PMID:Breast cancer and ovarian cancer genetics. 1621 1

Epidemiologic studies show a positive association between obesity and cancer risk. In addition to increased body adiposity and secretion of fat-derived hormones, obesity is also linked to insulin resistance, type 2 diabetes, and chronic inflammation. We used the fatless A-ZIP/F-1 transgenic mouse to dissociate the relative role of each of these underlying factors in the development of cancer. These mice are unique in that they do not have white fat but do develop type 2 diabetes. In two cancer models, the classic two-stage skin carcinogenesis protocol and the C3(1)/T-Ag transgenic mouse mammary tumor model, A-ZIP/F-1 mice displayed higher tumor incidence, tumor multiplicity, and decreased tumor latency than wild-type mice. We examined circulating levels of adipokines, growth factors, and cytokines. As expected, adipokines (i.e., leptin, adiponectin, and resistin) were undetectable or found at very low levels in the blood of fatless mice. However, insulin, insulin-like growth factor-I, growth hormone, vascular endothelial growth factor, and proinflammatory Th2 cytokines, such as interleukin (IL)-1beta, IL-4, and IL-6, were elevated in A-ZIP/F-1 mice. Additionally, we examined multiple phosphorylated proteins (i.e., protein kinase B/Akt and ErbB2/HER-2 kinase) associated with cancer development. Results show that many of these phosphorylated proteins were activated specifically in the A-ZIP/F-1 skin but not in the wild-type skin. These findings suggest that adipokines are not required for the promotion of tumor development and thus contradict the epidemiologic data linking obesity to carcinogenesis. We postulate that insulin resistance and inflammation are responsible for the positive correlation with cancer observed in A-ZIP/F-1 mice.
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PMID:Accelerated tumor formation in a fatless mouse with type 2 diabetes and inflammation. 1670 76

Obesity is a risk factor for postmenopausal breast cancer and is associated with poor prognosis. Leptin, a cytokine synthesized in adipose tissue, has been implicated as a link between obesity and breast cancer. In the present study, the effects of leptin on cell proliferation and proteins associated with leptin signaling and/or breast cell growth were investigated in ER-positive, MCF-7, T47-D and MDA-MB-361, and ER-negative, MDA-MB-231 and SK-BR-3, breast cancer cell lines. MDA-MB-361 and SK-BR-3 also overexpress HER2/neu. For proliferation assays, 96-well plates were used and for protein determinations cells were synchronized in 6-well plates for 18-24 h in serum-free medium. Leptin was added at 0, 5, 10, 25, 50 and 100 ng/ml for 24 and 48 h. For Western blot analyses, protein extracts were probed for Ob-Rb, Ob-R, leptin, Jak2, PI3K, Stat3, p-Stat3, PCNA, cyclin D1, Cox-2, VEGF, Bcl-2, Bcl-xL, Bax, insulin, IGF-I, IGFBP3, IGF-IRalpha, aromatase, CYP1A1 and CYP1B1. Overall, except for MCF-7 cells, leptin stimulated proliferation in all lines. MCF-7 cells expressed higher levels of Ob-Rb, Jak2, PI3K, Stat3 and p-Stat3 in a dose-dependent manner to 50 ng/ml at 24 h; and IGF-IRalpha increased at 24 h. Cyclin D1 and Cox-2 levels increased with leptin treatment. Higher CYP1B1 expression was observed at both 24 and 48 h. In MDA-MB-231 cells, p-Stat3 and Bcl-xL were increased at 48 h; whereas PCNA and cyclin D1 expression increased in leptin-treated cells at 24 and 48 h. In T47-D cells, Jak2 and Stat3 were elevated at higher leptin concentrations at 24 and 48 h. However, p-Stat3 and PCNA demonstrated an increase only in 48-h leptin-treated cells. Furthermore, cyclin D1 exhibited higher expression at both 24 and 48 h, while Bcl-xL expression was lower with increasing concentrations of leptin at 48 h. In MDA-MB-361 cells, Ob-Rb and VEGF increased at 24 and 48 h; whereas PI3K, Stat3, PCNA and insulin levels increased in leptin-treated MDA-MB-361 cells after 48 h. Bcl-2 and IGF-IRalpha were decreased at 24 h and a dose-dependent increase at 48 h was noted. Higher expression of CYP1B1 was observed with leptin for 24 h. In SK-BR-3 cells, Ob-R increased at both 24 and 48 h. A similar trend was found for IGF-I and IGFBP3 expression. Higher levels of Jak2 and PI3K were observed after 24 h. Interestingly, there was a gradual increase of leptin expression at 24 h, but a gradual decrease at 48 h in relation to the dose of leptin. In contrast, PCNA and IGF-IRalpha showed a decline at 24 h and an increase at 48 h. Elevated levels of cyclin D1, VEGF and Bax were detected at 48 h in cells and increased Cox-2 expression was observed at 24 h. These data indicate that leptin may influence breast cancer development in relation to ER status as well as to the presence or absence of HER2. Continued study on leptin may be helpful for a better understanding of breast cancer development in obese women.
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PMID:Effects of leptin on human breast cancer cell lines in relationship to estrogen receptor and HER2 status. 1748 72

Although the clinical relevance of molecular subtypes of breast cancer has been documented, little is known about risk factors for different tumor subtypes, especially the HER2-overexpressing and the triple-negative subtypes that have poor prognoses. Obesity may be differentially related to the risk of different subtypes given the various potential mechanisms underlying its association with breast cancer. We pooled two population-based case-control studies of postmenopausal breast cancer for an analysis, including 1,447 controls and 1,008 luminal (hormone receptor positive), 39 HER2-overexpressing (hormone receptor negative, HER2 positive), and 77 triple-negative (hormone receptor and HER2 negative) cases. Associations between anthropometric factors and the risk of different breast cancer subtypes were evaluated using polytomous logistic regression. Among women not currently using menopausal hormone therapy, body mass index (BMI) and weight were associated with the risk of luminal tumors [odds ratio (OR) comparing highest versus lowest quartiles, 1.7; 95% confidence interval (95% CI), 1.2-2.4 and OR, 1.7; 95% CI, 1.2-2.4, respectively] and suggestively associated with risk of triple-negative tumors (OR, 2.7; 95% CI, 1.0-7.5 and OR, 5.1; 95% CI, 1.1-23.0, respectively). Neither BMI nor weight was associated with the risk of any tumor subtype among hormone therapy users. The positive relationship between BMI and luminal tumors among postmenopausal women not using hormone therapy is well characterized in the literature. Although our sample size was limited, body size may also be related to the risk of postmenopausal triple-negative breast cancer among nonusers of hormone therapy. Given the expanding obesity epidemic, the widespread cessation of hormone therapy use, and the poor prognosis of triple-negative tumors, this novel finding merits confirmation.
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PMID:Body size and risk of luminal, HER2-overexpressing, and triple-negative breast cancer in postmenopausal women. 1866 48

Overweight and obesity is associated with an increased risk of postmenopausal breast cancer. However, less is known about the impact of anthropometric factors on tumor pathology and biology. A Swedish population-based prospective cohort study of 9,685 postmenopausal women not using hormonal replacement therapy (HRT) were followed for an average of 10.3 years during which 305 incident breast cancer cases were diagnosed. Invasive and sufficient tumor material was available in 248 cases. Pathological reevaluation of histological type and grade was conducted. Using a tissue microarray (TMA), the tumor expression of Ki67, HER2, ERalpha, ERbeta, PgR, cyclin D1 and p27 was evaluated. Six anthropometric factors: height, weight, body mass index (BMI), waist- and hip circumference and body fat percentage were categorized by quartiles of baseline anthropometric measurements, and relative risks were calculated using multivariate Cox regression models. Invasive breast cancer incidence was increased for women in the higher quartiles of all anthropometric measurements. Height was positively associated with Grade I and ERalpha-positive tumors. Women in the highest quartiles of weight, BMI, waist- and hip circumference and body fat percentage were all associated with tumors of ductal type, Grade II, low Ki67 index, HER2 negativity and low expression of the oncogene cyclin D1. Obesity was further associated with tumors expressing ERalpha and PgR but interestingly not ERbeta. This study confirmed previously described associations between overweight/obesity and increased risk of postmenopausal breast cancer. Furthermore, obesity was associated with tumors expressing several markers corresponding with low malignancy.
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PMID:Anthropometric factors in relation to different tumor biological subgroups of postmenopausal breast cancer. 1879 78

Recent experimental evidences begin to support the notion that the proto-oncogene HER2 (erbB-2) might unexpectedly function to modulate the adipogenic conversion of preadipocytes. Two opposing scenarios have been proposed, however, to explain the influence of HER2 on adipocyte differentiation. In one hand, down-modulation of HER2 expression and pharmacological reduction of HER2 activity have been related to enhanced adipocyte differentiation. On the contrary, an increased abundance in HER2 has been described in differentiated adipocytes compared with preadipocytes. Considering that expression and activity of the lipogenic enzyme Fatty Acid Synthase (FASN) become up-regulated during adipogenic conversion, we recently hypothesized that a "HER2 --> FASN axis" -a "lipogenic benefit" that has been shown to enhance cancer cell proliferation, survival, chemoresistance and metastasis in biologically aggressive subgroups of breast carcinomas-might also naturally work during the differentiation of preadipocytes. To definitely clarify if the discrepancy between the opposing theories for a role of HER2 during adipocyte differentiation related to the experimental approach utilized to compare the abundance of HER2 in undifferentiated and differentiated adipocytes (i.e., cell lysates containing equivalent protein content versus cell lysates generated from similar cell numbers), we here took advantage of a high content microscopy approach. Using an automated confocal imaging platform, we monitored the expression status of the adipogenic marker FASN and its timing relationship with HER2 not only in individual 3T3-L1 cells but further in whole cultures of 3T3-L1 preadipocytes undergoing adipogenic conversion. Our findings not only confirm a non-oncogenic role for HER2 in the process of adipose differentiation but further suggest that HER2 might represent a previously unrecognized target to manage obesity via the lipogenic enzyme FASN.
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PMID:The tyrosine kinase receptor HER2 (erbB-2): from oncogenesis to adipogenesis. 1881 84

Diets high in fat are associated with increased susceptibility to obesity and metabolic syndrome. Increased adipose tissue that is caused by high-fat diets (HFD) results in altered storage of lipophilic toxicants like 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), which may further increase susceptibility to metabolic syndrome. Because both TCDD and HFD are associated with increased breast cancer risk, we examined their effects on metabolic syndrome-associated phenotypes in three mouse models of breast cancer: 7,12-dimethylbenz[a]anthracene (DMBA), Tg(MMTV-Neu)202Mul/J (HER2), and TgN(MMTV-PyMT)634Mul/J (PyMT), all on an FVB/N genetic background. Pregnant mice dosed with 1 microg/kg of TCDD or vehicle on gestational day 12.5 were placed on a HFD or low-fat diet (LFD) at parturition. Body weights, percent body fat, and fasting blood glucose were measured longitudinally, and triglycerides were measured at study termination. On HFD, all cancer models reached the pubertal growth spurt ahead of FVB controls. Among mice fed HFD, the HER2 model had a greater increase in body weight and adipose tissue from puberty through adulthood compared with the PyMT and DMBA models. However, the DMBA model consistently had higher fasting blood glucose levels than the PyMT and HER2 models. TCDD only impacted serum triglycerides in the PyMT model maintained on HFD. Because the estrogenic activity of the HFD was three times lower than that of the LFD, differential dietary estrogenic activities did not drive the observed phenotypic differences. Rather, the HFD-dependent changes were cancer model dependent. These results show that cancer models can have differential effects on metabolic syndrome-associated phenotypes even before cancers arise.
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PMID:Mouse breast cancer model-dependent changes in metabolic syndrome-associated phenotypes caused by maternal dioxin exposure and dietary fat. 1884 Jul 65

The mechanism of the association between breast cancer and obesity remains unknown. To investigate this mice over-expressing HER2/Neu in the mammary gland (MMTV-HER2/Neu) were fed either a high-fat diet (45% of calories) (HFD) or low-fat diet (10%) (LFD) from 4 weeks of age and followed for up to 1 year, or sacrificed when a mammary tumor reached 1.5 cm. There was a small but significant increase in body weight on HFD (P < 0.05) and the HFD mice displayed a greater fat mass determined by MRI (P < 0.01). Mild glucose intolerance was observed from 3 months of age on HFD, but insulin levels were not elevated. While the time of onset of a first tumor and tumor growth rates were not altered, mice on HFD had an earlier onset of a second tumor and a twofold greater incidence (LFD 25%, HFD 54%) and a greater absolute number of multiple tumors (tumors/mouse, LFD 1.5 +/- 0.25 vs. HFD 2.7 +/- 0.23, P < 0.01). Consistent with a lack of hyperinsulinemia, immunoblotting of skeletal muscle lysates from mice injected with insulin showed no insulin resistance determined by the phosphorylation of Akt/PKB. Similarly, there was no difference in basal or maximum insulin-stimulated phosphorylation of IRS-1/2, Akt/PKB, or p70 S6K in tumor cell lysates from HFD and LFD groups. Immunohistochemistry revealed no difference in tumor tissue staining for the proliferative marker, Ki67, between diets. These data indicate that HFD, in the absence of significant insulin resistance, mediates a tumor promoting, but not a tumor growth effect in this model of mammary carcinogenesis.
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PMID:Evidence for a tumor promoting effect of high-fat diet independent of insulin resistance in HER2/Neu mammary carcinogenesis. 1985 63

The relationship between obesity, metabolic syndrome, diabetes and cancer has been recognized for many years. Multiple studies conducted in the last 20 years have identified molecular mechanisms responsible for this phenomenon. Elucidation of the important role of insulin, IGF receptor, mTOR and AMP-activated protein kinase in breast cancer biology has led to the development and subsequent clinical evaluation of novel targeted therapies, including IGF-1 receptor-specific antibodies or tyrosine kinase inhibitors and inhibitors of mTOR. There is also a growing interest in the use of metformin, which has been shown to possess antitumor activity resulting from activation of AMP-activated protein kinase and subsequent inhibiton of mTOR, as well as from decreased circulating insulin levels. Metformin has been shown to inhibit proliferation, invasion and angiogenesis of neoplastic cells and to overcome resistance of breast cancer to chemotherapy, hormonal therapy and HER2 inhibition. Recently, metformin has been demonstrated to inhibit breast cancer stem cell growth and to synergize with chemotherapy in suppression of tumor growth and prolongation of survival of breast tumor-bearing animals. Several currently ongoing Phase II and III clinical studies are evaluating the therapeutic efficacy of metformin in the treatment of early and advanced breast cancer patients.
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PMID:Obesity, hyperinsulinemia and breast cancer: novel targets and a novel role for metformin. 2046 5


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