Is Leptin a Mediator of Adverse Prognostic Effects of Obesity in Breast Cancer?

Physical Activity and Breast Cancer Survival-Epidemiologic Evidence and Potential Biologic Mechanisms

PURPOSE OF REVIEW

To review the biologic mechanisms that may be operative between physical activity and survival after breast cancer.

RECENT FINDINGS

Physical activity decreases risk of mortality from breast cancer by up to 40%. Several biologic mechanisms have been hypothesized to explain this association. Previous cohort studies and randomized trials have examined the primary mechanisms that appear to be operative, which involve a decrease in sex hormone levels, insulin resistance, and inflammation. The evidence is still inconsistent and several limitations in the existing literature exist. Understanding the biologic mechanisms involved in the association of physical activity and breast cancer survival will provide more precision to physical activity guidelines for cancer survival. To achieve this objective, future research should include direct measurements of physical activity, sedentary behaviour, and health-related fitness to provide a more comprehensive assessment of these factors and their association with biomarkers and survival after breast cancer.

Obesity and Breast Cancer Risk: The Oncogenic Implications of Metabolic Dysregulation

CONTEXT

Breast cancer is increasing in prevalence in parallel with rising rates of obesity worldwide. Obesity is recognized as a leading modifiable risk factor for the development of breast cancer; however, this association varies considerably by clinicopathologic features, and the underlying mechanisms are complex.

EVIDENCE ACQUISITION

Pubmed literature search using combinations of "obesity," "breast cancer risk," "diet," "exercise," "weight gain," "weight loss," "adipose tissue inflammation," "crown-like structure," "immune markers," "metformin," "gliflozins," "SGLT-2i," "GLP1-RA," and related terms.

EVIDENCE SYNTHESIS

Elevated body mass index and weight gain are associated with increased risk of postmenopausal, hormone receptor-positive breast cancer. Emerging evidence suggests that adverse measures of body composition in individuals of any weight can also confer increased breast cancer risk. Mechanistically, various factors including altered adipokine balance, dysfunctional adipose tissue, dysregulated insulin signaling, and chronic inflammation contribute to tumorigenesis. Weight loss and more specifically fat mass loss through lifestyle and pharmacologic interventions improve serum metabolic and inflammatory markers, sex hormone levels, and measures of breast density, suggesting a link to decreased breast cancer risk.

CONCLUSION

Incorporating markers of metabolic health and body composition measures with body mass index can capture breast cancer risk more comprehensively. Further studies of interventions targeting body fat levels are needed to curb the growing prevalence of obesity-related cancer.

Associations of insulin resistance and inflammatory biomarkers with endometrial cancer survival: The Alberta endometrial cancer cohort study

Background

Metabolic dysfunction and inflammation have been associated with endometrial cancer risk; however, their influence on endometrial cancer survival is less understood.

Methods

A prospective cohort study of 540 endometrial cancer cases diagnosed between 2002 and 2006 in Alberta were followed for survival outcomes to 2019. Baseline blood samples collected either pre‐ or post‐hysterectomy were analyzed for glucose, insulin, adiponectin, leptin, tumor necrosis factor‐α, interleukin‐6, and C‐reactive protein. Covariates were obtained during in‐person interviews and via medical chart abstraction. Cox proportional hazard regression models were used to estimate multivariable‐adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between each biomarker and disease‐free and overall survival.

Results

Blood samples were collected from 520 of the 540 participants (presurgical n = 235; postsurgical n = 285). During the median follow‐up of 14.3 years (range 0.4–16.5 years), there were 125 recurrences, progressions, and/or deaths with 106 overall deaths. None of the biomarkers were associated with disease‐free or overall survival in multivariable‐adjusted analyses. In an exploratory stratified analysis, the highest level of presurgical adiponectin, compared to the lowest level, was associated with improved disease‐free (HR = 0.42, 95% CI = 0.20–0.85) and overall (HR = 0.41, 95% CI = 0.18–0.92) survival, whereas no statistically significant associations were noted for postsurgical measures of adiponectin.

Conclusions

Overall, there was no evidence of an association between biomarkers of insulin resistance and inflammation with mortality outcomes in endometrial cancer survivors. Future cohort studies with serial blood samples are needed to understand the impact of changes in insulin resistance and inflammatory markers on endometrial cancer survival.

Crown-like structures in breast adipose tissue of breast cancer patients: associations with CD68 expression, obesity, metabolic factors and prognosis

Crown-like structures of the breast (CLS-B), defined by the clustering of macrophages (identified using CD68 immunohistochemical staining) to surround a dying adipocyte, are a sign of adipose-tissue inflammation. In human cohorts, CLS-B positively correlates with older age, obesity, dyslipidemia and higher levels of glucose, insulin, C-reactive protein and IL-6. In an existing cohort of early-stage breast cancer patients, CLS-B were identified using H&E stained histologic sections (hCLS-B), and by CD68 immunohistochemistry (CD68 + CLS-B). We examined associations of H&E and CD68-detected CLS-B with clinicopathologic features using χ2 tests, with metabolic factors using Wilcoxon rank sum tests and with disease free and overall survival using Cox regression models. hCLS-B were detected in 59 of 163 patients with slides (36.2%) and CD68 + CLS-B in 37 of 119 patients with paraffin blocks (31.1%). hCLS-B were positively correlated with higher weight (p = 0.003), BMI (p = 0.0008) and C-reactive protein (p = 0.045). CD68 + CLS-B were positively correlated with higher weight (p = 0.006), BMI p = 0.001), leptin (p = 0.034), insulin (p = 0.008) and Homeostasis Model Assessment (p = 0.027). CD68 + CLS-B were associated with poor distant disease-free with a hazard ratio (HR) of 2.81, 95% confidence interval (CI) 1.20-6.57, and overall survival with HR 3.97 (1.66-9.48), while hCLS-B were not associated with either: HR for distant recurrence 0.59 (0.26-1.30); HR for death 1.04 (0.50-2.16). The presence of hCLS-B and of CD68 + CLS-B were associated with obesity; CD68 + CLS-B were associated with insulin resistance and adverse prognosis. Similar patterns were not seen for hCLS-B. Research is needed to understand the biologic basis for these differences.

Visceral Adiposity and Cancer: Role in Pathogenesis and Prognosis

The prevalence of being overweight and obese has been expanded dramatically in recent years worldwide. Obesity usually occurs when the energetic introit overtakes energy expenditure from metabolic and physical activity, leading to fat accumulation mainly in the visceral depots. Excessive fat accumulation represents a risk factor for many chronic diseases, including cancer. Adiposity, chronic low-grade inflammation, and hyperinsulinemia are essential factors of obesity that also play a crucial role in tumor onset. In recent years, several strategies have been pointed toward boundary fat accumulation, thus limiting the burden of cancer attributable to obesity. While remodeling fat via adipocytes browning seems a tempting prospect, lifestyle interventions still represent the main pathway to prevent cancer and enhance the efficacy of treatments. Specifically, the Mediterranean Diet stands out as one of the best dietary approaches to curtail visceral adiposity and, therefore, cancer risk. In this Review, the close relationship between obesity and cancer has been investigated, highlighting the biological mechanisms at the basis of this link. Finally, strategies to remodel fat, including browning and lifestyle interventions, have been taken into consideration as a major perspective to limit excess body weight and tumor onset.

Endogenous estradiol and inflammation biomarkers: potential interacting mechanisms of obesity-related disease

PURPOSE

Disentangling the effects of endogenous estrogens and inflammation on obesity-related diseases requires a clearer understanding of how the two biological mechanisms relate to each other.

METHODS

We studied 155 healthy postmenopausal women not taking menopausal hormone therapy enrolled in the Prostate Lung Colorectal and Ovarian (PLCO) screening cancer trial. From a baseline blood draw, we measured endogenous estradiol and 69 inflammation biomarkers: cytokines, chemokines, adipokines, angiogenic factors, growth factors, acute phase proteins, and soluble receptors. We evaluated the estradiol-inflammation relationship by assessing associations across different models (linear, ordinal logistic, and binary logistic) using a variety of estradiol classifications. We additionally investigated the estradiol-inflammation relationship stratified by baseline obesity status (BMI < 30 stratum and BMI > 30 stratum).

RESULTS

Associations of estradiol with 7 inflammation biomarkers met p < 0.05 statistical significance in linear and ordinal models: C-reactive protein (CRP), adiponectin, chemokine (C-X-C motif) ligand-6, thymus activation-regulated chemokine, eosinophil chemotactic protein, plasminogen activator inhibitor-1, and serum amyloid A. The positive association between estradiol and CRP was robust to model changes. Each standard deviation increase in endogenous estradiol doubled a woman's odds of having CRP levels higher than the study median (odds ratio 2.29; 95% confidence interval 1.28, 4.09). Estradiol was consistently inversely associated with adiponectin. Other estradiol-inflammation biomarker associations were not robust to model changes.

CONCLUSIONS

Endogenous estradiol appears to be associated with CRP and adiponectin; the evidence is limited for other inflammation biomarkers.

Adipokines as therapeutic targets in breast cancer treatment

INTRODUCTION

Adipocytes, which represent a substantial part of the tumor microenvironment in breast cancer, secrete several adipokines that affect tumorigenesis, cancer progression, metastasis, and treatment resistance via multiple signaling pathways. Areas covered: In this review, we focus on the role of leptin, adiponectin, autotaxin, and interleukin-6 in breast cancer initiation, progression, metastasis, and drug response. Furthermore, we investigated adipokines as potential targets of breast cancer-specific drugs. Expert opinion: Adipokines and adipokine receptors are deregulated in breast cancer. Adipokines play various roles in breast cancer initiation, progression, metastasis, and drug response, hence, adipokine signaling could be an effective drug target. Several clinical trials are in progress to test the efficacy of adipokine targeting agents. However, adipokines also affect metabolic homeostasis; hence, the adverse effects of the targeted drug should be investigated and addressed.

Leptin promotes migration and invasion of breast cancer cells by stimulating IL-8 production in M2 macrophages

This study aims to investigate the mechanisms underlying leptin-mediated crosstalk between tumor-associated macrophages (M2 macrophages) and breast cancer cells. THP1 human leukemic monocytes were induced to differentiate into M2 macrophages by PMA (100 nM) and IL-4 (20 ng/mL). Quantitative RT-PCR and Western blot revealed that leptin (100 nM) significantly increased the expression of leptin receptor (ObR) in the M2 macrophages (P < 0.01) and stimulated interleukin (IL)-8 expression in the M2 macrophages, mouse macrophage cells RAW264.7, and primary mouse peritoneal macrophages in a dose- and time-dependent manner. Leptin-induced IL-8 production was sensitive to the ERK inhibitor PD980590 (10 μmol/L), p38 MAPK inhibitor SB203580 (20 μmol/L), and anti-ObR neutralizing antibody (4 μg/mL). Leptin (100 ng/mL) substantially increased the phosphorylation of p38 and ERK1/2. Thus, leptin may induce IL-8 production in M2 macrophages by interacting with ObR to activate the p38 and ERK signaling pathways. Scratch and transwell chamber assay showed that both recombinant IL-8 and leptin-induced M2 macrophage-derived IL-8 promoted the migration and invasion of human breast cancer cells MCF7 and MDA-MB-231 (All P < 0.01). In a nude mice xenograft model of breast cancer (n = 5 per group), injection of leptin (0.1 μg/g) dramatically increased tumor volume and mass, reduced survival, exacerbated pulmonary metastasis, and elevated IL-8 and Ki67 expression in the tumor tissue (All P < 0.05) compared with PBS injection. Depletion of mouse macrophage by Clophosome®-clodronate liposome and injection of anti-mouse IL-8 neutralizing antibodies in the xenograft tumor significantly attenuated those leptin-mediated stimulations (All P < 0.05). These findings indicate that leptin may promote tumor growth and metastasis by stimulating IL-8 production in tumor-associated macrophage.

Obesity and breast cancer outcomes in chemotherapy patients in New Zealand - a population-based cohort study

BACKGROUND

Obesity has been reported as an adverse prognostic factor in breast cancer, but inconsistently, and under-treatment with chemotherapy may occur. We provide the first assessment of obesity and breast cancer outcomes in a population-based, multi-ethnic cohort of New Zealand patients treated with chemotherapy.

METHODS

All 3536 women diagnosed with invasive breast cancer in the Waikato region of New Zealand from 2000-2014 were registered and followed until last follow-up in specialist or primary care, death or Dec 2014; median follow-up 4.1 years. For the 1049 patients receiving chemotherapy, mortality from breast cancer, other causes, and all causes, and rates of loco-regional and of distant recurrence, were assessed by body mass index (BMI), recorded after diagnosis, adjusting for other clinico-pathological and demographic factors by Cox regression.

RESULTS

BMI was known for 98% (n=1049); 33% were overweight (BMI 25-29.9), 21% were obese (BMI 30-34.9), and 14% were very obese (BMI 35+). There were no significant associations between obesity and survival, after adjustment for demographic and clinical factors (hazard ratios, HR, for very obese compared to BMI 21-24, for breast cancer deaths 0.96 (0.56-1.67), and for all deaths 1.03 (0.63-1.67), respectively, and only small non-significant associations for loco-regional or metastatic recurrence rates (HR 1.17 and 1.33 respectively). Subgroup analyses by age, menopausal status, ethnicity, stage, post-surgical radiotherapy, mode of diagnosis, type of surgery, and receptor status, showed no associations. No associations were seen with BMI as a continuous variable. The results in all patients irrespective of treatment but with recorded BMI data (n=2296) showed similar results.

CONCLUSIONS

In this population, obesity assessed post-diagnosis had no effect on survival or recurrence, based on 1049 patients with chemotherapy treatment with follow-up up to 14 years.

Serum adiponectin but not leptin at diagnosis as a predictor of breast cancer survival

Limited numbers of epidemiological studies have examined the relationship between adipokines and breast cancer survival. Preoperative serum levels of obesity-related adipokines (leptin and adiponectin) were here measured in 370 breast cancer patients, recruited from two hospitals in Korea. We examined the association between those adipokines and disease-free survival (DFS). The TNM stage, ER status and histological grade were aslo assessed in relation to breast cancer survival. Elevated adiponectin levels were associated with reduced DFS of breast cancer (Ptrend=0.03) among patients with normal body weight, predominantly in postmenopausal women. There was no association of leptin with breast cancer survival. In conclusion, our study suggests that high levels of adiponectin at diagnosis are associated with breast cancer survival among women with normal body weight.

Association of Obesity-Related Metabolic Disruptions With Cancer Risk and Outcome

Over the past 40 years, the prevalence of obesity has increased epidemically worldwide, which raises significant concerns regarding public health and the associated economic burden. Obesity is a major risk factor for several conditions including cardiovascular disease and type 2 diabetes, and recent evidence suggests that obesity negatively affects cancer risk and outcome. The relationship between obesity and cancer is complex and involves multiple factors both at the systemic and cellular level. Indeed, disruptions in insulin metabolism, adipokines, inflammation, and sex hormones all contribute to the adverse effects of obesity in cancer development and progression. The focus of this review will be the impact of these systemic obesity-related factors on cancer biology, incidence, and outcome. Potential therapeutic interventions and current clinical trials targeting obesity and its associated factors will also be discussed.

Body mass index and treatment outcomes following neoadjuvant therapy in women aged 45 y or younger: Evidence from a historic cohort

PURPOSE

Large and consistent evidence supports the role of body mass index (BMI) as a prognostic and predictive indicator in breast cancer. However, there is paucity of data specifically referred to women diagnosed at a young age across the different disease settings. We investigated the impact of BMI on treatment outcomes in 86 breast cancer patients aged 45 y or less treated with neoadjuvant chemotherapy (CT) followed by surgery.

METHODS

Pathologic complete response (pCR) was defined as the eradication of cancer from both breast and lymph nodes. Overall survival (OS) and disease-free survival (DFS) were calculated using the Kaplan-Meier product-limit method. Curves were compared by long rank test for significance. Potential predictors of survival were tested in Cox models.

RESULTS

We observed a pCR in 19 patients (22%). Lower values of BMI were more commonly associated with pCR (p = 0.05). Results from univariate, but not multivariate, models were somewhat supportive of higher pCR rates in leaner women (p = 0.06). None of the variables impacted DFS. OS was longer in leaner patients (medians and 95%CI: 74.6 months, 66.2-82.9 and 58.5 months, 49.6-67.4, p = 0.009). Longer OS was also related to lower T-stage, adjuvant radiotherapy (RT), and non triple negative (TN) subtype (p = 0.046, p = 0.024, and p = 0.015, respectively). Cox models confirmed the protective role of lower BMI (Hazard Ratios: 0.30, 95%CI: 0.12-0.71, p = 0.007), non TN subtype and adjuvant RT (p = 0.008 and p = 0.024).

CONCLUSIONS

In young breast cancer patients treated with neoadjuvant CT followed by surgery, lower values of BMI are associated with longer OS. Our data also showed longer OS in association with a non TN molecular subtype and adjuvant RT. The modifiable nature of BMI and aggressive biologic behavior of the disease diagnosed at a young age encourage further studies to corroborate our findings.

Obesity as a risk factor in cancer: A national consensus of the Spanish Society for the Study of Obesity and the Spanish Society of Medical Oncology

In the last few years, many prospective studies have demonstrated a clear association between obesity and cancers of the colon and rectum, breast in post-menopausal women, endometrium, kidney, oesophagus and pancreas. Obesity is also associated with a high risk of recurrence and cancer-related death. The pathophysiology of obesity involves various changes that may be implicated in the relationship between obesity and cancer, such as excess inflammatory cytokines and chronic inflammation, hyperinsulinaemia, insulin resistance, and raised leptin and oestrogens. The Spanish Society for the Study of Obesity and the Spanish Society of Medical Oncology have signed a cooperation agreement to work together towards reducing the impact of obesity in cancer. Preventing obesity prevents cancer.

Effect of metformin vs placebo on and metabolic factors in NCIC CTG MA.32

BACKGROUND

Metformin may improve metabolic factors (insulin, glucose, leptin, highly sensitive C-reactive protein [hs-CRP]) associated with poor breast cancer outcomes. The NCIC Clinical Trials Group (NCIC CTG) MA.32 investigates effects of metformin vs placebo on invasive disease-free survival and other outcomes in early breast cancer. Maintaining blinding of investigators to outcomes, we conducted a planned, Data Safety Monitoring Committee-approved, analysis of the effect of metformin vs placebo on weight and metabolic factors at six months, including examination of interactions with baseline body mass index (BMI) and insulin, in the first 492 patients with paired blood samples.

METHODS

Eligible nondiabetic subjects with T1-3, N0-3, M0 breast cancer who had completed surgery and (neo)adjuvant chemotherapy (if given) provided fasting plasma samples at random assignment and at six months. Glucose was measured locally; blood was aliquoted, frozen, and stored at -80°C. Paired plasma aliquots were analyzed for insulin, hs-CRP, and leptin. Spearman correlation coefficients were calculated and comparisons analyzed using Wilcoxon signed rank test. All statistical tests were two-sided.

RESULTS

Mean age was 52.1±9.5 years in the metformin group and 52.6 ± 9.8 years in the placebo group. Arms were balanced for estrogen/progesterone receptor, BMI, prior (neo)adjuvant chemotherapy, and stage. At six months, decreases in weight and blood variables were statistically significantly greater in the metformin arm (vs placebo) in univariate analyses: weight -3.0%, glucose -3.8%, insulin -11.1%, homeostasis model assessment -17.1%, leptin -20.2%, hs-CRP -6.7%; all P values were less than or equal to .03. There was no statistically significant interaction of change in these variables with baseline BMI or insulin.

CONCLUSIONS

Metformin statistically significantly improved weight, insulin, glucose, leptin, and CRP at six months. Effects did not vary by baseline BMI or fasting insulin.

Synergy of leptin/STAT3 with HER2 receptor induces tamoxifen resistance in breast cancer cells through regulation of apoptosis-related genes

PURPOSE

Tamoxifen is a major treatment modality for estrogen receptor positive breast cancer, but the occurrence of resistance remains a problem. Recently, obesity-related leptin has been found to interfere with tamoxifen in breast cancer MCF-7 cells. In the present study we investigated the effect of leptin on three tamoxifen-treated breast cancer cell types (i.e., MDA-MB-231, MCF-7 and MCF-7/HER2).

METHODS

The effect of tamoxifen/leptin treatment was evaluated using a MTT cell viability assay. mRNA expression was assessed by real time PCR and protein expression by Western blotting. WWOX, Survivin and BCL2 gene promoter activities were evaluated by chromatin immunoprecipitation.

RESULTS

Cell viability assays revealed that estrogen receptor negative MDA-MB-231 cells were resistant, that estrogen receptor positive MCF-7 cells were sensitive and that MCF-7/HER2 cells were relatively resistant to tamoxifen, while leptin co-administration 'rescued' MCF-7 and, especially, MCF-7/HER2 cells from the anti-proliferative effect of tamoxifen. The cell lines also exhibited a different phosphorylation status of STAT3, a transcription factor that is activated by the obesity related leptin receptor b (Ob-Rb). Most importantly, chromatin immunoprecipitation assays revealed differential STAT3 binding to the anti-apoptotic BCL2 and pro-apoptotic WWOX gene promoters in MCF-7 and MCF-7/HER2 cells, leading to concomitant modifications of its mRNA/protein expression levels, thus providing a selective advantage to HER2 over-expressing MCF-7/HER2 cells after treatment with tamoxifen and tamoxifen plus leptin.

CONCLUSIONS

Our study provides novel evidence indicating that synergy between the leptin/Ob-Rb/STAT3 signalling pathway and the HER2 receptor protects tamoxifen-treated HER2 over-expressing cells from the inhibitory effect of tamoxifen through differential regulation of apoptosis-related genes.

Impact of the obesity epidemic on cancer

There is growing appreciation that the current obesity epidemic is associated with increases in cancer incidence at a population level and may lead to poor cancer outcomes; concurrent decreases in cancer mortality at a population level may represent a paradox, i.e., they may also reflect improvements in the diagnosis and treatment of cancer that mask obesity effects. An association of obesity with cancer is biologically plausible because adipose tissue is biologically active, secreting estrogens, adipokines, and cytokines. In obesity, adipose tissue reprogramming may lead to insulin resistance, with or without diabetes, and it may contribute to cancer growth and progression locally or through systemic effects. Obesity-associated changes impact cancer in a complex fashion, potentially acting directly on cells through pathways, such as the phosphoinositide 3-kinase (PI3K) and Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways, or indirectly via changes in the tumor microenvironment. Approaches to obesity management are discussed, and the potential for pharmacologic interventions that target the obesity-cancer link is addressed.

Leptin induces upregulation of sphingosine kinase 1 in oestrogen receptor-negative breast cancer via Src family kinase-mediated, janus kinase 2-independent pathway

INTRODUCTION

Obesity is a known risk factor for breast cancer. Sphingosine kinase 1 (SK1) is an oncogenic lipid kinase that is overexpressed in breast tumours and linked with poor prognosis, however, its role in obesity-driven breast cancer was never elucidated.

METHODS

Human primary and secondary breast cancer tissues were analysed for SK1 and leptin receptor expression using quantitative real-time polymerase chain reaction (qRT-PCR) assay. Leptin-induced signalling was analysed in human oestrogen receptor (ER)-positive and negative breast cancer cells using Western blotting, qRT-PCR and radiolabelling assays.

RESULTS

Our findings show for the first time that human primary breast tumours and associated lymph node metastases exhibit a strong correlation between SK1 and leptin receptor expression (Pearson R = 0.78 and R = 0.77, respectively, P <0.001). Both these genes are elevated in metastases of ER-negative patients and show a significant increase in patients with higher body mass index (BMI). Leptin induces SK1 expression and activation in ER-negative breast cancer cell lines MDAMB-231 and BT-549, but not in ER-positive cell lines. Pharmacological inhibition and gene knockdown showed that leptin-induced SK1 activity and expression are mediated by activation of extracellular signal-regulated kinases 1/2 (ERK1/2) and Src family kinase (SFK) pathways, but not by the major pathways downstream of leptin receptor (LEPR) - janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3). Src-homology 2 domain-containing phosphatase 2 (SHP2) appeared to be key to SK1 activation, and may function as an adaptor protein between SFKs and LEPR. Importantly, leptin-induced breast cancer cell proliferation was abrogated by SK1-specific small interfering RNA (siRNA).

CONCLUSIONS

Overall, our findings demonstrate a novel SFK/ERK1/2-mediated pathway that links leptin signalling and expression of oncogenic enzyme SK1 in breast tumours and suggest the potential significance of this pathway in ER-negative breast cancer.

Randomized trial of a telephone-based weight loss intervention in postmenopausal women with breast cancer receiving letrozole: the LISA trial

PURPOSE

Obesity is associated with poor outcomes in women with operable breast cancer. Lifestyle interventions (LIs) that help women reduce their weight may improve outcomes.

PATIENTS AND METHODS

We conducted a multicenter randomized trial comparing mail-based delivery of general health information alone or combined with a 24-month standardized, telephone-based LI that included diet (500 to 1,000 kcal per day deficit) and physical activity (150 to 200 minutes of moderate-intensity physical activity per week) goals to achieve weight loss (up to 10%). Women receiving adjuvant letrozole for T1-3N0-3M0 breast cancer with a body mass index (BMI) ≥ 24 kg/m(2) were eligible. Weight was measured in the clinic, and self-report physical activity, quality-of-life (QOL), and diet questionnaires were completed. The primary outcome was disease-free survival. Accrual was terminated at 338 of 2,150 planned patients because of loss of funding.

RESULTS

Mean weight loss was significantly (P < .001) greater in the LI arm versus the comparison arm (4.3 v 0.6 kg or 5.3% v 0.7% at 6 months and 3.1 v 0.3 kg or 3.6% v 0.4% at 24 months) and occurred consistently across strata (BMI 24 to < 30 v ≥ 30 kg/m(2); prior v no prior adjuvant chemotherapy). Weight loss was greatest in those with higher baseline levels of moderate-intensity physical activity or improvement in QOL. Hospitalization rates and medical events were similar.

CONCLUSION

A telephone-based LI led to significant weight loss that was still evident at 24 months, without adverse effects on QOL, hospitalizations, or medical events. Adequately powered randomized trials with cancer end points are needed.

Body mass index and survival in women with breast cancer-systematic literature review and meta-analysis of 82 follow-up studies

BACKGROUND

Positive association between obesity and survival after breast cancer was demonstrated in previous meta-analyses of published data, but only the results for the comparison of obese versus non-obese was summarised.

METHODS

We systematically searched in MEDLINE and EMBASE for follow-up studies of breast cancer survivors with body mass index (BMI) before and after diagnosis, and total and cause-specific mortality until June 2013, as part of the World Cancer Research Fund Continuous Update Project. Random-effects meta-analyses were conducted to explore the magnitude and the shape of the associations.

RESULTS

Eighty-two studies, including 213 075 breast cancer survivors with 41 477 deaths (23 182 from breast cancer) were identified. For BMI before diagnosis, compared with normal weight women, the summary relative risks (RRs) of total mortality were 1.41 [95% confidence interval (CI) 1.29-1.53] for obese (BMI >30.0), 1.07 (95 CI 1.02-1.12) for overweight (BMI 25.0-<30.0) and 1.10 (95% CI 0.92-1.31) for underweight (BMI <18.5) women. For obese women, the summary RRs were 1.75 (95% CI 1.26-2.41) for pre-menopausal and 1.34 (95% CI 1.18-1.53) for post-menopausal breast cancer. For each 5 kg/m(2) increment of BMI before, <12 months after, and ≥12 months after diagnosis, increased risks of 17%, 11%, and 8% for total mortality, and 18%, 14%, and 29% for breast cancer mortality were observed, respectively.

CONCLUSIONS

Obesity is associated with poorer overall and breast cancer survival in pre- and post-menopausal breast cancer, regardless of when BMI is ascertained. Being overweight is also related to a higher risk of mortality. Randomised clinical trials are needed to test interventions for weight loss and maintenance on survival in women with breast cancer.

Effect of body mass index on tumor characteristics and disease-free survival in patients from the HER2-positive adjuvant trastuzumab trial N9831

BACKGROUND

Data suggest that weight, and specifically body mass index (BMI), plays a role in breast cancer development and outcome. The authors hypothesized that there would be a correlation between BMI and clinical outcome in patients with early stage, human epidermal receptor 2 (HER2)-positive breast cancer enrolled in the N9831 adjuvant trial.

METHODS

Patients were grouped according to baseline BMI as follows: normal (BMI <25 kg/m(2)), overweight (BMI ≥25 kg/m(2) and <30 kg/m(2)), and obese (BMI ≥30 kg/m(2)). Disease-free survival (DFS) was estimated using the Kaplan-Meier method. Comparisons between treatment arms A, B, and C (chemotherapy with or without trastuzumab) were performed using a stratified Cox proportional hazards model.

RESULTS

Analysis was completed on 3017 eligible patients. Obese patients were more likely to be older and postmenopausal (P < .0001 for both), to have larger tumors (P = .002), and to have positive lymph nodes (P = .004). In the pooled analysis cohort, differences in DFS among the BMI groups were statistically significant (5-year DFS rate: 82.5%, 78.6%, and 78.5% for normal weight, overweight, and obese women, respectively; log-rank P = .02). The adjusted hazard ratio comparing the DFS of overweight women with the DFS of normal women was 1.30 (95% confidence interval, 1.06-1.61); and, comparing the DFS of obese women with the DFS normal women, the adjusted hazard ratio was 1.31 (95% confidence interval, 1.07-1.59). There were no statistically significant differences in DFS by weight group for women within any trial arm.

CONCLUSIONS

Patients with early stage, HER2-positive breast cancer and normal BMI had a better 5-year DFS compared with overweight and obese women. The current results indicated that adjuvant trastuzumab improves clinical outcome regardless of BMI.

Differences between Hispanic and non-Hispanic white women with breast cancer for clinical characteristics and their correlates

PURPOSE

Body size and ethnicity may influence breast cancer tumor characteristics at diagnosis. We compared Hispanic and non-Hispanic white (NHW) cases for stage of disease, estrogen receptor (ER) status, tumor size, and lymph node status, and the associations of these with body size in the 4-Corners Breast Cancer Study.

METHODS

One thousand five hundred twenty-seven NHW and 798 Hispanic primary incident breast cancer cases diagnosed between October 1999 and May 2004 were included. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by multiple logistic regression.

RESULTS

Hispanic women were more likely to have larger (>1 cm) ER- tumors and more than four positive lymph nodes (P < .003). Lymph node status was not associated with body size. However, among NHW women, obesity (body mass index >30) and increased waist circumference (>38.5 inches) were significantly positively associated with ER- tumor status (OR, 1.87; 95% CI, 1.24-2.81 and OR, 2.59; 95% CI, 1.58-4.22, respectively). In contrast, among Hispanic women, obesity and waist circumference had inverse associations with ER- tumor status (OR, 0.49; 95% CI, 0.29-0.84 and OR, 0.56; 95% CI, 0.30-1.05, respectively).

CONCLUSIONS

Hispanic ethnicity may modify the association of body size and composition with ER- breast cancer. This finding could have relevance to clinical treatment and prognosis.

Leptin attenuates the anti-estrogen effect of tamoxifen in breast cancer

BACKGROUND

Leptin is a circulating peptide hormone, encoded by the obesity (ob) gene, acting as a regulator of food intake via hypothalamic-mediated effects. Recent studies have shown that leptin and leptin receptor (ObR) are involved in the carcinogenesis and development of breast cancer. In addition, functional cross talk between leptin and estrogen signaling has been registered. Here, we investigated the relation of leptin and ObR expression with survival in women with breast cancer treated with the anti-estrogen tamoxifen, and whether leptin can interfere with the estrogen receptor alpha (ERα) and the effect of tamoxifen in breast cancer cells.

METHODS

The protein expression of leptin and ObR(b) in 114 breast cancer samples was evaluated by immunohistochemistry, quantified by Immunoreactivity Score (IRS) and correlated to survival and other clinicopathological features. The expression of ObR(b) in ERα positive MCF-7 breast cancer cells was examined by immunofluorescence and western blot. Leptin effect on cell proliferation was determined by MTT assay. The interference of leptin with tamoxifen on ERα degradation was studied by western blot and immunofluorescence. Effects of leptin on the transcriptional activity of ERα were explored using luciferase reporter assays.

RESULTS

Positive staining (Immunoreactivity Score, IRS≥1) of leptin and ObR isoform ObRb in breast cancer tissues were seen in 79.8% and 85.1% of patients respectively. In overall and in tamoxifen-treated breast cancer patients, leptin expression (IRS≥1) correlated with poor prognosis, (log-rank test, P=0.016, overall; P=0.031, tamoxifen-treated). Overexpressed ObRb was found by western blotting andimmunofluorescence in MCF-7 as well as in MDA-MB-231, T47D, and MDA-MB-435 cell lines. Tamoxifen (1000μM) significantly inhibited the proliferation of MCF-7 cells, degraded ERα and reduced ERα-dependent transcription from estrogen response element-containing promoter. On the contrary, simultaneous treatment with leptin (100ng/ml) significantly attenuated these effects, similar to the effects of estradiol.

CONCLUSIONS

Leptin correlated significantly with poor prognosis in overall and tamoxifen-treated breast cancer patients. Leptin interferes with the action of tamoxifen in MCF-7 cells, at least partly, through inducing increased nuclear expression of ERα. Thus, leptin may contribute to tamoxifen resistance and consequently, leptin suppression could be a novel way of circumventing resistance to anti-estrogen treatment.

Pre-diagnosis body mass index and survival after breast cancer in the After Breast Cancer Pooling Project

Obese and underweight women who develop breast cancer may have poorer survival compared with normal-weight women. However, the optimal weight for best prognosis is still under study. We conducted a prospective investigation of pre-diagnosis body mass index (BMI) and mortality among 14,948 breast cancer patients in the After Breast Cancer Pooling Project. Breast cancer patients diagnosed from 1990 to 2006 with AJCC Stage I-III breast tumors were drawn from four prospective cohorts. Hazard ratios (HR) and 95% confidence intervals (CI) representing the associations of BMI categories (World Health Organization international classifications) with recurrence and mortality were estimated using delayed entry Cox proportional hazards models. Obese (30 to < 35 kg/m(2)), severely obese (35 to < 40 kg/m(2)), and morbidly obese (≥ 40 kg/m(2)) were examined. After a mean follow-up of 7.8 years, 2,140 deaths and 2,065 recurrences were documented. Both underweight (HR = 1.59; 95% CI: 1.18, 2.13) and morbidly obese women (HR = 1.81; 95% CI: 1.42, 2.32) had the greatest risk of overall mortality compared with normal weight (18.5-24.9 kg/m(2)) women. Severe obesity (HR = 1.09; 95% CI: 0.88, 1.36) and obesity (HR = 1.11; 95% CI: 0.97, 1.27) were related to small non-significant increased risks. Overweight (25.0-29.9 kg/m(2)) was not associated with any excess risk compared with normal weight. Similar associations were found for breast cancer death and non-breast cancer death but not recurrence. Women who were underweight and morbidly obese before breast cancer diagnosis were at the greatest risk of all-cause mortality. Morbidly obese women were also at increased risk of death from breast cancer. These results suggest that degree of obesity confers differential risk on survival.

Insulin- and obesity-related variables in early-stage breast cancer: correlations and time course of prognostic associations

PURPOSE

To investigate patterns of prognostic associations over time of insulin- and obesity-related variables measured at diagnosis of early breast cancer (BC), focusing on whether the prognostic associations with distant recurrence and death changed over time.

PATIENTS AND METHODS

Five hundred thirty-five nondiabetic women with T1-3, N0-1, M0 invasive BC diagnosed from 1989 to 1996 were included in the study. Insulin-related variables included fasting insulin, Homeostasis Model Assessment, C-peptide, and glucose. Obesity-related variables included weight, body mass index (BMI), waist and hip circumference, and leptin. Correlations were examined using the Pearson correlation coefficient and prognostic associations using the Cox model.

RESULTS

There was evidence that associations of baseline insulin-related variables with distant recurrence and death were not constant over time; univariable adverse prognostic associations were significant only during the first 5 years (eg, insulin quartile 4 v 1: hazard ratio [HR], 2.32; 95% CI, 1.39 to 3.86; P < .001 for distant disease-free survival [DDFS]; and HR, 2.85; 95% CI, 1.48 to 5.50; P = .002 for overall survival [OS], with little attenuation of this pattern in multivariable analyses). In contrast, obesity-related variables (BMI, weight, leptin) exerted significant adverse univariable associations that were constant over time (eg, BMI quartile 4 v 2: HR, 1.40; 95% CI, 1.07 to 1.82 for DDFS; P = .014; and HR, 1.50; 95% CI, 1.16 to 1.93; P < .001 for OS); prognostic associations of leptin remained significant in multivariable analyses.

CONCLUSION

Baseline insulin- and obesity-related variables exert different patterns of prognostic associations over time in early BC.

Obesity, inflammation, and postmenopausal breast cancer: therapeutic implications

Breast cancer is the female malignant neoplasia with the highest incidence in the industrialized world. Although early diagnosis has contributed to therapeutic success, breast cancer remains a major health issue. In the last few year the hormone therapy for estrogen-dependent breast cancer has evolved achieving significant clinical results; at the same time, it has enabled us to better define the role of estrogens in the etiopathogenesis of this tumour. Weight increase and obesity have been identified as the most important risk and prognostic factors for breast cancer in postmenopausal women. Several hypotheses have been proposed to explain the association of obesity with postmenopausal breast cancer. Specific obesity-associated factors, including leptin, insulin and inflammatory mediators, seem to influence breast cancer growth and prognosis independently of estrogens and at least in part by interacting with estrogen signalling at a cellular level. Therefore, a careful assessment of the nutritional status and body composition is paramount for a proper therapeutic approach for postmenopausal breast carcinoma. The use of antidiabetic and anti-inflammatory drugs associated with conventional hormone therapies and dietary/physical interventions could offer a new therapeutic approach for breast carcinoma that develops in the context of adiposity.

Obesity and survival among black women and white women 35 to 64 years of age at diagnosis with invasive breast cancer

PURPOSE

To evaluate the effect of obesity on survival among black women and white women with invasive breast cancer and to determine whether obesity explains the poorer survival of black women relative to white women.

PATIENTS AND METHODS

We observed 4,538 (1,604 black, 2,934 white) women who were 35 to 64 years of age when diagnosed with incident invasive breast cancer between 1994 and 1998. Multivariate Cox regression models were used to examine the effect of body mass index (BMI, in kilograms per square meter) 5 years before diagnosis on risk of death from any cause and from breast cancer.

RESULTS

During a median of 8.6 years of follow-up, 1,053 women died (519 black, 534 white), 828 as a result of breast cancer (412 black, 416 white). Black women were more likely to die than white women (multivariate-adjusted relative risk [RR], 1.33; 95% CI, 1.16 to 1.53). Compared with women with BMI of 20 to 24.9 kg/m(2), those who were obese (BMI ≥ 30 kg/m(2)) had a greater risk of all-cause mortality (RR, 1.23; 95% CI, 1.04 to 1.47) and breast cancer-specific mortality (RR, 1.20; 95% CI, 0.99 to 1.46). These associations were observed among white women (all-cause RR, 1.54; 95% CI, 1.21 to 1.96; breast cancer RR, 1.46; 95% CI, 1.11 to 1.92), but not among black women (all-cause RR, 1.03; 95% CI, 0.81 to 1.29; breast cancer RR, 1.02; 95% CI, 0.79 to 1.33).

CONCLUSION

Obesity may play an important role in mortality among white but not black patients with breast cancer. It is unlikely that differences in obesity distributions between black women and white women account for the poorer survival of black women.

Leptin and breast cancer: an overview

Leptin is a well-known mediator of obesity. Leptin and its receptor are overexpressed in breast cancer, especially in high-grade tumors. It has an association with progression and poor survival of breast cancer. Leptin can regulate endothelial cell proliferation and promote angiogenesis. There are several other factors such as insulin and HER2 may be involved in the relationship between leptin and breast cancer. Leptin system has emerged as a new and promising therapeutic target for breast cancer. This review article summarizes the current knowledge about the relation of leptin and breast cancer.

Factors affecting survival among women with breast cancer in Hawaii

BACKGROUND

Given previous reports of ethnic differences in breast cancer survival among Hawaii's population, we investigated the role of adherence to treatment standards, treatment toxicity, preexisting chronic conditions, and obesity in the survival of 382 prospectively studied breast cancer patients representing six ethnic groups.

METHODS

Participants were recruited from several hospitals in Honolulu. Information on tumor characteristics and treatment was abstracted from medical records. Based on the Physicians Data Query (PDQ®), we assessed compliance with recommended treatment guidelines. Vital status and cause of death data were obtained through linkage with the Hawaii Tumor Registry. Cox proportional hazard models were used to compute hazard ratios for predictors of survival.

RESULTS

After a median follow-up time of 13.2 ± 3.7 years, 115 deaths had occurred, 43 from breast cancer and 72 from other causes. After adjustment, we observed only small differences in survival by ethnicity that were not statistically significant. In addition to advanced disease stage, obesity at diagnosis was a significant independent predictor of worse and receiving PDQ-recommended treatment of better breast cancer-specific and all-cause survival. Developing high-grade toxicity was associated with worse breast cancer survival, whereas comorbidity and older age at diagnosis were associated with higher all-cause mortality. Hormone receptor status, menopausal status, and type of health insurance were not associated with survival.

CONCLUSIONS

These findings suggest that given access to healthcare, breast cancer patients experience similar survival rates. Although more information about mechanisms of action would be useful, it appears reasonable to recommend weight control to breast cancer survivors.

Zeranol may increase the risk of leptin-induced neoplasia in human breast

Breast cancer and obesity are serious health problems and their relationship has been studied for many years. Leptin is mainly secreted by adipocytes and plays a key role in breast cancer development. Leptin expression is up-regulated in obese individuals and promotes breast cancer cell growth. On the other hand, exposure to environmental estrogens has been found to be directly related to breast cancer. Zeranol (Z) is a non-steroidal anabolic growth promoter used in the beef industry in the US. This study focused on the evaluation of Z and Z-containing sera (ZS) and its adverse health risk to human consumption of Z-containing meat produced from Z-implanted beef cattle. We hypothesized that Z increases the risk of breast neoplasia in women, particularly in obese women. A cell proliferation assay, ELISA analysis, RT-PCR and Western blot analysis were conducted. Our study demonstrated that Z and ZS collected from Z-implanted heifers stimulated the proliferation of primary cultured human normal breast epithelial cells (HNBECs) by up-regulating cyclin D1 expression. Leptin increased the sensitivity of HNBECs to Z, and Z increased the ability of HNBECs to secrete leptin. These results suggest an interaction between leptin and Z in HNBECs. Furthermore, Z may play a role in leptin-induced breast neoplasia.

Regenerative therapy and cancer: in vitro and in vivo studies of the interaction between adipose-derived stem cells and breast cancer cells from clinical isolates

Adipose-derived stem cells (ASCs) have been proposed to stabilize autologous fat grafts for regenerative therapy, but their safety is unknown in the setting of reconstructive surgery after mastectomy. Both bone marrow mesenchymal stem cells (MSCs) and ASC have been shown to enhance tumorigenesis of established breast cancer cell lines, but primary patient material has not been tested. Here, we ask whether ASC promote the in vitro growth and in vivo tumorigenesis of metastatic breast cancer clinical isolates. Metastatic pleural effusion (MPE) cells were used for coculture experiments. ASC enhanced the proliferation of MPE cells in vitro (5.1-fold). For xenograft experiments (100 sorted cells/injection site), nonhematopoietic MPE cells were sorted into resting and active populations: CD90+ resting (low scatter, 2.1%≥2N DNA), CD90+ active (high scatter, 10.6%≥2N DNA), and CD90-. Resting CD90+ MPE cells were tumorigenic in 4/40 sites but growth was not augmented by ASC. Active CD90+ MPE cells were tumorigenic (17/40 sites) only when coinjected with ASC (p=0.0005, χ2 test). The multilineage potentiality and MSC-like immunophenotype of ASC were confirmed by flow cytometry, differentiation cultures, and immunostaining. The secretome profile of ASC resembled that reported for MSC, but included adipose-associated adipsin and the hormone leptin, shown to promote breast cancer growth. Our data indicate that ASC enhance the growth of active, but not resting tumor cells. Thus, reconstructive therapy utilizing ASC-augmented whole fat should be postponed until there is no evidence of active disease.

Expression of estrogen receptor alpha increases leptin-induced STAT3 activity in breast cancer cells

Adipositas correlates with an enhanced risk of developing malignant diseases such as breast cancer, endometrial tumor or prostate carcinoma, but the molecular basis for this is not well understood. Potential mechanisms include increased bioavailability of adipocytokines (e.g. leptin) and steroid hormones. Here, we investigated cross-talk between ERalpha (estrogen receptor alpha) and leptin-induced activation of signal transducer and activator of transcription 3 (STAT3), a transactivator of important oncogenes. Upon leptin binding to its receptor Ob-RL (obesity receptor), STAT3 tyrosine phosphorylation and transactivation activity were enhanced by simultaneously expressing ERalpha. Downregulation of ERalpha using small interfering RNA abolished leptin-induced STAT3 phosphorylation. Interestingly, leptin-mediated STAT3 activation was unaffected by co-stimulation with the ERalpha ligands estradiol (E2) or estrogen antagonists ICI182,780 and tamoxifen, implying that enhancement of leptin-mediated STAT3 activity is independent of ERalpha ligands. We also detected ERalpha binding to STAT3 and JAK2 (Janus kinase 2), resulting in enhanced JAK2 activity upstream of STAT3 in response to leptin that might lead to an increased ERalpha-dependent cell viability. Altogether, our results indicate that leptin-induced STAT3 activation acts as a key event in ERalpha-dependent development of malignant diseases.

Correlation of body mass index and leptin with tumor size and stage of disease in hormone-dependent postmenopausal breast cancer: preliminary results and therapeutic implications

Obesity is considered the most important risk and prognostic factor for estrogen-dependent breast cancer in postmenopausal women. Adipokines, in particular leptin, are at the center of the etiopathogenetic mechanisms by which obesity and related metabolic disorders influence breast cancer risk and its prognosis. The present prospective observational study aims to investigate the relationship between body mass index (BMI), serum levels of leptin and proinflammatory cytokines, and breast cancer prognostic factors. In the study, 98 postmenopausal and 82 premenopausal patients with ER-positive breast cancer participated. During the same study period, 221 control subjects were simultaneously recruited. Women underwent baseline measurements pre-operatively, before any surgical and systemic treatments. Pathologic characteristics of tumors were abstracted from pathology reports. Leptin and proinflammatory cytokines were assayed in stored fasting blood specimens. In postmenopausal breast cancer patients, BMI, leptin, and interleukin-6 significantly correlated with pathological tumor classification (pT) and TNM stage. Multivariate regression analysis showed that BMI and leptin, but not interleukin-6, were independent predictive variables of pT and TNM stage. Our results seem to suggest a twofold role of leptin in the etiopathogenesis of postmenopausal estrogen-positive breast cancer. Indeed, leptin reflects the total amount of fat mass, which correlates to aromatase activity and subsequent estrogens levels. Further studies are warranted to clarify the role of leptin and interleukin-6 in breast carcinogenesis and identify new therapeutic options, beyond the use of aromatase inhibitors, acting selectively on adipokine-driven pathways.

Adipose tissue as target organ in the treatment of hormone-dependent breast cancer: new therapeutic perspectives

Breast cancer is the female malignant neoplasia with the highest incidence in the industrialized world. Despite many undeniable therapeutic successes obtained, breast cancer still remains, however, a major health issue. In the last few years, thanks to aromatase inhibitors, the hormone therapy for oestrogen-dependent breast cancer has evolved in terms of efficacy and tolerability; at the same time, it has enabled us to better define the role of oestrogens in the etiopathogenesis of this tumour. Weight increase and obesity have been identified as the most important risk and prognostic factors for breast cancer in postmenopausal women. Several hypotheses have been proposed to explain the association of obesity with postmenopausal breast cancer. A more recent hypothesis suggests that adipocytes and their autocrine (paracrine and endocrine actions) are at the centre of such an etiopathogenetic mechanism. A better understanding of the main mechanisms that link together menopause, body-weight increase and hormone-dependent breast cancer is paramount to enable the identification of key molecules involved in the development of breast carcinoma and suggest new therapeutic options. The present review will discuss important findings on the therapeutic aspects of adipose tissue and adipokines as a target for treatment of hormone-dependent breast cancer.

Common genetic variations in the LEP and LEPR genes, obesity and breast cancer incidence and survival

Obesity is a strong risk factor for breast cancer in postmenopausal women and adverse prognostic indicator regardless of menopausal status. Leptin is an important regulator of adipose tissue mass and has been associated with tumor cell growth. Leptin exerts its effects through interaction with the leptin receptor (LEPR). We investigated whether genetic variations in the leptin (LEP) and LEPR genes are associated with risk of breast cancer, or once diagnosed, with survival. The polymorphisms LEP G-2548A and LEPR Q223R were characterized in population-based study consisting of mostly European-American women. The study examined 1,065 women diagnosed with first, primary invasive breast cancer between 1996 and 1997. Controls were 1,108 women frequency matched to the cases by 5-year age group. A modest increase in risk of developing breast cancer was associated with the LEP -2548AA genotype when compared to the LEP -2548GG genotype (age-adjusted OR = 1.30; 95% CI = 1.01-1.66). This association was stronger among postmenopausal women who were obese (OR = 1.86; 95% CI = 0.95-3.64) although the interaction was of borderline statistical significance (P = 0.07). We found no evidence of an association with polymorphisms of either LEP or LEPR in relation to all-cause or breast cancer-specific mortality among women with breast cancer (mean follow-up time = 66.7 months). The effects of these genotypes on breast cancer risk and mortality did not vary significantly when stratified by menopausal status. In summary, our results show that a common variant in LEP may be associated with the risk of developing breast cancer supporting the hypothesis that leptin is involved in breast carcinogenesis.

Leptin induces migration and invasion of glioma cells through MMP-13 production

Leptin, the product of the obese gene, plays an important role in the regulation of body weight by coordinating metabolism, feeding behavior, energy balance, and neuroendocrine responses. However, regulation of leptin gene expression in the central nervous system is different from that in the adipocytes. In addition, leptin has been found in many tumor cell lines and has been shown to have mitogenic and angiogenic activity in a number of cell types. Glioma is the most common primary adult brain tumor with poor prognosis because of the spreading of tumor cell to the other regions of brain easily. Here we found that malignant C6 glioma cells expressed more leptin and leptin receptors than nonmalignant astrocytes. Furthermore, it was found that exogenous application of leptin enhanced the migration and invasion of C6 glioma cells. In addition, we found that the expression of matrix metalloproteinase-13 (MMP-13) but not of MMP-2 and MMP-9 was increased in response to leptin stimulation. The leptin-induced increase of cell migration and invasion was antagonized by MMP-13 neutralizing antibody or silencing MMP-13. The up-regulation of MMP-13 induced by leptin was mainly through p38 MAP kinase and NF-kappaB pathway. In addition, migration-prone sublines demonstrate that cells with increasing migration ability had more expression of MMP-13 and leptin. Taken together, these results indicate that leptin enhanced migration and invasion of C6 glioma cells through the increase of MMP-13 production.

Involvement of the leptin receptor in the immune response in intestinal cancer

The incidence of colorectal cancers (CRC) may be influenced by environmental factors, including nutrition. The role of peptides regulating food intake in controlling the growth and recurrence of human tumors is controversial. Leptin, a cytokine-like peptide, regulates food intake. We investigated the expression of leptin and its receptor in 171 consecutive patients (78 female and 93 male; 71 years) with CRC. Leptin concentrations in the serum (ELISA) were determined before tumor removal. ObRb was characterized in tumors and normal homologous tissues and culture cells (HT29, HCT116, and HCT116 with a transferred chromosome 3) by using immunocytochemistry, immunohistochemistry, reverse transcription-PCR (RT-PCR), and Western blotting. Microsatellite instability (MSI) phenotype was characterized by immunohistochemistry and pentaplex PCR. mRNAs of cytokines and chemokines were quantified in tumors and in normal homologous tissues (RT-PCR) in 43 patients. Adequate statistical tests, including multivariate analysis adjusted for pathologic tumor-node-metastasis (pTNM), MSI-H, and ObRb phenotypes, were used. Higher expression of ObRb in tumors compared with the homologous normal mucosa, pTNM staging but not leptin serum level, was associated with patients' progression-free survival (PFS). Tumor ObRb phenotype and pTNM were independent predictive factors of PFS. ObRb was more strongly expressed in HCT116 cells than in HCT116-Ch3 cells as well as in MSI-H tumors than in microsatellite stability and potentially associated with efficient cytotoxic antitumoral response as assessed by immunohistochemistry and RT-PCR measurements. We suggest that leptin receptor expression in tumors is involved in adaptive immune response in sporadic colon and rectal tumors likely via MSI-H phenotype orientation.

Leptin/HER2 crosstalk in breast cancer: in vitro study and preliminary in vivo analysis

Background

Obesity in postmenopausal women is associated with increased breast cancer risk, development of more aggressive tumors and resistance to certain anti-breast cancer treatments. Some of these effects might be mediated by obesity hormone leptin, acting independently or modulating other signaling pathways. Here we focused on the link between leptin and HER2. We tested if HER2 and the leptin receptor (ObR) can be coexpressed in breast cancer cell models, whether these two receptors can physically interact, and whether leptin can transactivate HER2. Next, we studied if leptin/ObR can coexist with HER2 in breast cancer tissues, and if presence of these two systems correlates with specific clinicopathological features.

Methods

Expression of ObR, HER2, phospo-HER2 was assessed by immonoblotting. Physical interactions between ObR and HER2 were probed by immunoprecipitation and fluorescent immunostaining. Expression of leptin and ObR in breast cancer tissues was detected by immunohistochemistry (IHC). Associations among markers studied by IHC were evaluated using Fisher's exact test for count data.

Results

HER2 and ObR were coexpressed in all studied breast cancer cell lines. In MCF-7 cells, HER2 physically interacted with ObR and leptin treatment increased HER2 phosphorylation on Tyr 1248. In 59 breast cancers, the presence of leptin was correlated with ObR (the overall association was about 93%). This result was confirmed both in HER2-positive and in HER2-negative subgroups. The expression of leptin or ObR was numerically more frequent in larger (> 10 mm) tumors.

Conclusion

Coexpression of HER2 and the leptin/ObR system might contribute to enhanced HER2 activity and reduced sensitivity to anti-HER2 treatments.

Postmenopausal vaginal atrophy correlates with decreased estradiol and body mass index and does not depend on the time since menopause

OBJECTIVE

To evaluate the relationship between morphologic cell characteristics in Papanicolaou (Pap) smears and serum estradiol, body mass index (BMI) and the time elapsed since menopause. Study design. In 92 women Pap smears were grouped into atrophic and mature cell patterns and compared with estradiol, BMI and the time since menopause.

RESULTS

Forty-one patients with mature cell pattern were on average 7.1 years from menopause and 51 patients with atrophic pattern 8.2 years, but this difference was not significant. Estradiol in patients with mature cell pattern was significantly higher (52.1 +/- 48.5 pmol/l) than in patients with atrophic pattern (25.6 +/- 40.0 pmol/l). Similarly, BMI was significantly higher (27.9 +/- 4.2 kg/m(2)) in patients with mature cell pattern than in patients with atrophic pattern (25.7 +/- 3.8 kg/m(2)). There was no significant correlation between the time since menopause and estradiol among patients with mature and atrophic cell pattern. The same was true for the correlation between the time from menopause and BMI in patients with mature and atrophic pattern.

CONCLUSIONS

Estradiol and BMI are associated with vaginal cell maturation and atrophy in postmenopausal women. Vaginal cell atrophy does not depend on the time since menopause.

Prognostic value of body mass index in locally advanced breast cancer

PURPOSE

The purpose of this retrospective study was to determine the association and prognostic value of body mass index (BMI) at the time of initial diagnosis in patients with locally advanced breast cancer (LABC). The analysis includes the subsets of inflammatory (IBC) and noninflammatory (non-IBC LABC) breast cancer.

EXPERIMENTAL DESIGN

We identified 602 patients who had LABC treated on prospective clinical trials. BMI was divided into three groups: (a) < or =24.9 (normal/underweight), (b) 25.0 to 29.9 (overweight), and (c) > or =30 (obese). Kaplan-Meier product limit method was used to estimate survival outcomes. Cox proportional hazards were used to determine associations between survival and BMI and to test for an interaction between BMI and breast cancer type.

RESULTS

Eighty-two percent had non-IBC LABC and 18% had IBC. Obese patients tended to have a higher incidence of IBC compared with overweight and normal/underweight groups (P = 0.01). Median follow up was 6 years for all patients. Median overall survival (OS) and recurrence-free survival (RFS) were 8.8 and 5.9 years, respectively. Patients with LABC who were obese or overweight had a significantly worse OS and RFS (P = 0.001) and a higher incidence of visceral recurrence compared with normal/underweight patients. In a multivariable model, BMI remained significantly associated with both OS and RFS for the entire cohort. The interactions between BMI and LABC subsets and between BMI and menopausal status were not statistically significant.

CONCLUSION

Patients with LABC and high BMI have a worse prognosis. Evaluation of the biological factors associated with this observation can provide tools for additional therapeutic interventions.

Dietary fiber is associated with serum sex hormones and insulin-related peptides in postmenopausal breast cancer survivors

OBJECTIVE

To measure the association between dietary fiber intake and eleven hormones and peptides in postmenopausal breast cancer survivors.

METHODS

Intake of fiber from food and supplements was measured two to three years after breast cancer diagnosis in 493 postmenopausal women from three western states. Concurrently, a fasting blood sample was obtained for assay of estrone, estradiol, free estradiol, testosterone, free testosterone, dehydroepiandrosterone sulfate, sex hormone-binding globulin (SHBG), leptin, C-peptide, insulin-like growth factor-1 (IGF1), and IGF-binding protein-3. Adjusted means of these hormones and peptides were calculated for categories of fiber intake.

RESULTS

High intake of dietary fiber was significantly (P<or=0.05) associated with low serum levels of estradiol and free estradiol and with high serum levels of IGF1. The combination of high dietary fiber intake and use of fiber supplements was additionally associated with low serum levels of C-peptide. The magnitude of the difference in hormone/peptide values, comparing high fiber intake to low fiber intake, varied from 16 to 28%, and the associations were independent of multiple confounding variables.

CONCLUSION

High fiber diets may be beneficial to postmenopausal breast cancer survivors due to fiber's favorable influence on sex hormones and peptides known to affect breast cancer prognosis.