Oestrogen/insulin-like growth factor-I receptor interaction in early breast cancer: clinical implications

Analysis of 17β-estradiol (E2) role in the regulation of corpus luteum function in pregnant rats: Involvement of IGFBP5 in the E2-mediated actions

BACKGROUND

In several species, considerably higher levels of estradiol-17 (E2) are synthesized in the CL. E2 has been suggested to participate in the regulation of luteal steroidogenesis and luteal cell morphology. In pregnant rats, several experiments have been carried out to examine the effects of inhibition of luteal E2 synthesis on CL structure and function.

METHODS

During days 12-15 of pregnancy in rats, luteal E2 was inhibited by way of daily oral administration of anastrozole (AI), a selective non-steroidal aromatase inhibitor, and experiments were also performed with E2 replacement i.e. AI+ E2 treatments. Luteal tissues from different treatment groups were subjected to microarray analysis and the differentially expressed genes in E2 treated group were further examined for expression of specific E2 responsive genes. Additional experiments were carried out employing recombinant growth hormone preparation and flutamide, an androgen receptor antagonist, to further address the specificity of E2 effects on the luteal tissue.

RESULTS

Microarray analysis of CL collected on day 16 of pregnancy post AI and AI+E2 treatments showed significantly lowered cyp19a1 expression, E2 levels and differential expression of a number of genes, and several of them were reversed in E2 replacement studies. From the differentially expressed genes, a number of E2 responsive genes were identified. In CL of AI pregnant rats, non-significant increase in expression of igf1, significant increase in igbp5, igf1r and decrease in expression of Erα were observed. In liver of AI treated rats, igf1 expression did not increase, but GH treatment significantly increased expression that was further increased with AI treatment. In CL of GH and AI+GH treated rats, expression of igfbp5 was higher. Administration of flutamide during days 12-15 of pregnancy resulted in non-significant increase in igfbp5 expression, however, combination of flutamide+AI treatments caused increased protein expression. Expression of few of the molecules in PI3K/Akt kinase pathway in different treatments was determined.

CONCLUSIONS

The results suggest a role for E2 in the regulation of luteal steroidogenesis, morphology and proliferation. igfbp5 was identified as one the E2 responsive genes with important role in the mediation of E2 actions such as E2-induced phosphorylation of PI3K/Akt kinase pathway.

Expression of estrogen receptors in non-malignant mammary tissue modifies the association between insulin-like growth factor 1 and breast cancer risk

BACKGROUND

Several studies have reported that the insulin-like growth factor 1 (IGF-1) is positively associated with estrogen receptor-positive [ER(+)] breast cancer risk, whereas there is little or no association with respect to ER(-) breast cancer. All comparisons of ER(+) breast cancer cases, however, have been made versus healthy controls, for whom there is no information about the ER expression in their mammary gland.

PATIENTS AND METHODS

In the context of a case-control investigation conducted in Athens, Greece, we studied 102 women with incident ERα(+) breast cancer and compared their IGF-1 blood levels with those of 178 ERα(+) and 83 ERα(-) women with benign breast disease (BBD) who underwent biopsies in the context of their standard medical care. Data were analysed using multiple logistic regression and controlling for potential confounding variables.

RESULTS

ERα(+) breast cancer patients had higher IGF-1 levels compared with women with BBD [odds ratio (OR) 1.36, 95% confidence interval (CI): 0.95-1.94, per 1 standard deviation (SD) increase in IGF-1 levels]. When ERα status of women with BBD was taken into account, the difference in IGF-1 levels between ERα(+) breast cancer patients and women with BBD was clearly driven by the comparison with BBD women who were ERα(+) (OR = 1.95, 95% CI: 1.31-2.89 per 1 SD increase in IGF-1 levels), whereas there was essentially no association with IGF-1 levels when ERα(+) breast cancer patients were compared with ERα(-) BBD women. These contrasts were particularly evident among post/peri-menopausal women.

CONCLUSIONS

We found evidence in support of an interaction of IGF-1 with the expression of ERα in the non-malignant mammary tissue in the context of breast cancer pathogenesis. This is in line with previous evidence suggesting that IGF-1 increases the risk of ER(+) breast cancer.

Insulin-like growth factor I and risk of breast cancer by age and hormone receptor status-A prospective study within the EPIC cohort

Experimental evidence shows cross-talk in mammary cells between estrogen, insulin-like growth factor I (IGF-I) and their respective receptors and possible synergistic effects of estrogen receptor (ER) activation and increased IGF-I signaling with regard to breast tumor development, and epidemiological evidence suggests that circulating IGF-I levels may be related more to the risk of ER-positive than ER-negative breast cancer. Using a case-control study nested within the prospective European EPIC cohort (938 breast cancer cases and 1,394 matched control subjects), we analyzed the relationships of prediagnostic serum IGF-I levels with the risk of estrogen and progesterone receptor-positive and -negative breast tumors. IGF-I levels were positively associated with the risk of ER+ breast tumors overall (pre- and postmenopausal women combined, odds ratio (OR)Q4-Q1 = 1.41 [95% confidence interval (CI) 1.01-1.98] for the highest vs. lowest quartile; OR = 1.17 [95% CI 1.04-1.33] per 1-standard deviation (SD) increase in IGF-I, ptrend = 0.01) and among women who were diagnosed with breast cancer at 50 years or older (ORQ3-Q1 = 1.38 [95% CI 1.01-1.89]; OR = 1.19 [95% CI 1.04-1.36] per 1-SD increase in IGF-I, ptrend = 0.01) but not with receptor-positive disease diagnosed at an earlier age. No statistically significant associations were observed for ER- breast tumors overall and by age at diagnosis. Tests for heterogeneity by receptor status of the tumor were not statistically significant, except for women diagnosed with breast cancer at 50 years or older (phet = 0.03 for ER+/PR+ vs. ER-/PR- disease). Our data add to a global body of evidence indicating that higher circulating IGF-I levels may increase risk specifically of receptor-positive, but not receptor-negative, breast cancer diagnosed at 50 years or older.

Extensive pure ductal carcinoma in situ of the breast: identification of predictors of associated infiltrating carcinoma and lymph node metastasis before immediate reconstructive surgery

AIM

To identify predictors for infiltrating carcinoma and lymph node involvement, before immediate breast reconstructive surgery, in patients with an initial diagnosis of extensive pure ductal carcinoma in situ of the breast (DCIS).

PATIENTS AND METHODS

Between January 2000 and December 2009, 241 patients with pure extensive DCIS in preoperative biopsy had underwent mastectomy. Axillary staging (sentinel node and/or axillary dissection) was performed in 92% (n = 221) of patients. Patients with micro-invasive lesions at initial diagnosis, recurrence or contralateral breast cancer were excluded.

RESULTS

Respectively 14% and 21% of patients had a final diagnosis of micro-invasive carcinoma (MIC) and invasive ductal carcinoma (IDC). Univariate analysis showed that the following variables at diagnosis were significantly correlated with the presence of either MIC or IDC in the mastectomy specimen: palpable tumor (p = 0.002), high grade DCIS (p = 0.002) and detection of an opacity by mammography (p = 0.019). Axillary lymph node (ALN) involvement was reported in 9% of patients. Univariate analysis suggested that a body mass index higher than 25 (p = 0.007), a palpable tumor (p = 0.012) and the detection of an opacity by mammography (p = 0.044) were associated with an increased rate of ALN involvement.

CONCLUSION

Skin-sparing mastectomy and immediate breast reconstruction (IBRS) has become increasingly popular, especially for patients with extended DCIS of the breast. This study confirmed that extended DCIS is associated with a substantial risk of finding MIC or IDC on the surgical specimen but also ALN involvement. Adjuvant systemic treatment and/or radiotherapy could be indicated for some of these patients after the surgery. Patients should be informed of the rate of 1) complications associated to IBRS that will potentially delay the introduction of systemic or local therapy 2) complications associated to radiotherapy after IBRS.

Body mass index and body surface area and their associations with outcomes in stage II and III colon cancer

BACKGROUND

Our study aims were to measure the associations between body mass index (BMI) and body surface area (BSA) with outcomes for stage II and III colon cancer and to evaluate if the effect of obesity is modified by disease stage and receipt of adjuvant therapy.

METHODS

Using a prospective cohort of stage II and III colon cancer patients who were referred between 2001 and 2005, we compared 3-year relapse-free survival (3-year RFS), 5-year cancer-specific survival (5-year CSS), and 5-year overall survival (5-year OS) rates among different BMI and BSA categories. Cox proportional-hazards models were constructed to explore the relationships between different body compositions and outcomes while adjusting for confounders.

RESULTS

Postoperative height and weight were used to classify 913 patients as normal weight (n = 424, BMI <25 kg/m(2)), overweight (n = 319, BMI 25-30 kg/m(2)), and obese (n = 170, BMI >30 kg/m(2)). Using Mosteller formula, 684 subjects had normal BSA (≤ 2.0 m(2)) and 229 had high BSA (>2.0 m(2)). Obese subjects experienced similar 3-year RFS (61.9 vs. 66.5 vs. 63.6 %, p = 0.51), 5-year CSS (65.6 vs. 72.4 vs. 68.0 %, p = 0.22), and 5-year OS (60.8 vs. 64.0 vs. 62.2 %, p = 0.69) when compared to overweight subjects and those with normal BMIs, respectively. Likewise, individuals with high BSA had similar outcomes as those with normal BSA (66.2 vs. 63.6 %, p = 0.64 for 3-year RFS, 70.3 vs. 68.6 %, p = 0.62 for 5-year CSS, and 64.5 vs. 61.9 %, p = 0.48 for 5-year OS). In Cox models, advanced age, male gender, stage III disease, and poor performance status correlated with inferior RFS, CSS, and OS, but BMI and BSA did not.

CONCLUSIONS

Obesity as measured by either BMI or BSA was not associated with differences in outcomes in stage II and III colon cancer.

Interaction between IGF-IR and ER induced by E2 and IGF-I

Estrogen receptor (ER) is a nuclear receptor and the insulin-like growth factor-I (IGF-I) receptor (IGF-IR) is a transmembrane tyrosine kinase receptor. Estrogen and IGF-I are known to have synergistic effects on the growth of breast cancer cells. Recently, non-nuclear effects of ER have been under investigation. To study the mechanism involved in this process, we have used MCF-7 breast cancer cell lines transfected with IGF-IR anti-sense cDNA (SX13, MCF-7(SX13)) that resulted in 50% reduction of IGF-IR. In MCF-7 cells, estradiol (E2) and IGF-I induced the rapid association of ER to IGF-IR, however, the interaction was abrogated in MCF-7(SX13) cells. In addition, NWTB3 cells (NIH3T3 cells overexpressing IGF-IR) were transiently transfected with ERα, the ER-IGF-IR interaction was induced by both E2 and IGF-I. Moreover, ERα regulated the IGF-I signaling pathways through phosphorylation of ERK1/2 and Akt and the interaction of ER-IGF-IR potentiated the cell growth. Finally, E2 and IGF-I stimulated translocation of ER from the nucleus to the cytoplasm. Taken together, these findings reveal that the interaction of the ER and IGF-IR is important for the non-genomic effects of ER.

Neo-endocrinochemotherapy: a novel approach for enhancing chemotherapeutic efficacy in clinic?

Chemosensitization means enhancing the sensitivity of tumor cells to chemotherapy with certain methods for better efficacy. Tumor progression depends on stimulation of multiple hormones, decrease in hormones during chemotherapy induces G0/G1 arrest of tumor cells, which may be the main cause for chemoresistance. Some of the choriocarcinoma and testicular tumors are curable with chemotherapy only, underlying mechanism may refer high level of human chorionic gonadotropin, which has thyroid stimulating hormone like effect and even induce hyperthyroidism in these patients. Some of these patients usually have high levels of thyroid hormones or suffer thyroid crisis during chemotherapy. Possibly owning to the proliferative or metabolic promotion effect of thyroid hormones and/or other endocrine hormones, which can promote tumor cells in G0 phase metabolizing actively or stepping into division cycle again, tumors are more sensitive to chemotherapy. Both endocrinotherapy and chemotherapy are major therapies for tumor, traditional endocrinotherapy suppresses tumor progression through decreasing tumor-dependent hormones or competitively combining and blocking hormone receptors. While, chemotherapy mostly killed tumor cells that proliferate actively, because tumor cells retardant in G0 phase by endocrinotherapy are no more sensitive to chemotherapy, endocrinotherapy cannot be concurrently used with chemotherapy. Nevertheless, decrease in hormones during chemotherapy is similar to concurrently using endocrinotherapy and chemotherapy. It has been found in some basic researches that some chemotherapeutics concurrently combined with endocrine hormones can achieve better efficacy compared with chemotherapy only. It is therefore hypothesized in this article that decrease in hormones during chemotherapy causes cell cycle arrest and renders tumor cells insensitive to chemotherapy; addition of endocrine hormones to mimic the hormones and microenvironment changes during chemotherapy for patients with choriocarcinoma or testicular tumor-curable with chemotherapy only, will rescue tumor cells from cell cycle arrest rendering them sensitive to chemotherapy. This new combinative therapy of concurrently using endocrine hormones and chemotherapy is defined as choriocarcinoma-mimic chemotherapy or neo-endocrinochemotherapy to distinguish the routine term of endocrinochemotherapy and is expected to be a novel approach to enhance chemotherapeutic efficacy in clinic.

Differential expression of growth factor receptors and membrane-bound tumor markers for imaging in male and female breast cancer

Introduction

Male breast cancer accounts for 0.5–1% of all breast cancers and is generally diagnosed at higher stage than female breast cancers and therefore might benefit from earlier detection and targeted therapy. Except for HER2 and EGFR, little is known about expression of growth factor receptors in male breast cancer. We therefore investigated expression profiles of growth factor receptors and membrane-bound tumor markers in male breast cancer and gynecomastia, in comparison with female breast cancer.

Methods

Tissue microarrays containing 133 male breast cancer and 32 gynecomastia cases were stained by immunohistochemistry for a panel of membrane-bound targets and compared with data on 266 female breast cancers.

Results

Growth factor receptors were variably expressed in 4.5% (MET) up to 38.5% (IGF1-R) of male breast cancers. Compared to female breast cancer, IGF1-R and carbonic anhydrase 12 (CAXII) were more frequently and CD44v6, MET and FGFR2 less frequently expressed in male breast cancer. Expression of EGFR, HER2, CAIX, and GLUT1 was not significantly different between male and female breast cancer. Further, 48.1% of male breast cancers expressed at least one and 18.0% expressed multiple growth factor receptors. Since individual membrane receptors are expressed in only half of male breast cancers, a panel of membrane markers will be required for molecular imaging strategies to reach sensitivity. A potential panel of markers for molecular imaging, consisting of EGFR, IGF1-R, FGFR2, CD44v6, CAXII, GLUT1, and CD44v6 was positive in 77% of male breast cancers, comparable to female breast cancers.

Conclusions

Expression patterns of growth factor receptors and hypoxia membrane proteins in male breast cancer are different from female breast cancer. For molecular imaging strategies, a putative panel consisting of markers for EGFR, IGF1-R, FGFR2, GLUT1, CAXII, CD44v6 was positive in 77% of cases and might be considered for development of molecular tracers for male breast cancer.

A metabolic phenotyping approach to understanding relationships between metabolic syndrome and breast tumour responses to chemotherapy

PURPOSE

Breast cancer is associated with adverse outcomes in patients with the metabolic syndrome phenotype. To study this further, we examined the relationship between serum metabolite levels and the components of metabolic syndrome with treatment outcomes in breast cancer.

METHODS

A total of 88 women with measurable breast cancer were studied; their serum metabolites as assessed by (1)H nuclear magnetic resonance spectroscopy, blood pressure, lipids, glucose, body mass index and waist circumference were recorded and correlated with treatment response.

RESULTS

We identified metabolic syndrome in approximately half of our cohort (42 patients) and observed a significant trend (P = 0.03) of increased incidence of metabolic syndrome in partial response (33.3%), stable disease (42.9%) and progressive disease groups (66.1%). High blood sugar predicted a poor response (P < 0.001). Logistic regression of metabonomic data demonstrated that high lactate (P = 0.03) and low alanine (P = 0.01) combined with high glucose (P = 0.01) were associated with disease progression.

CONCLUSIONS

Metabolic syndrome is commonly observed in metastatic breast cancer and these patients have poorer outcomes. These data, which support our previous findings, suggest that high blood glucose as part of metabolic syndrome is associated with a poor response in breast cancer. They also validate new therapeutic approaches that focus on metabolism.

Estrogen receptor dependent gene expression by osteoblasts - direct, indirect, circumspect, and speculative effects

Hormone activated estrogen receptors (ERs) have long been appreciated as potent mediators of gene expression in female reproductive tissues. These highly targeted responses likely evolved from more elemental roles in lower organisms, in agreement with their widespread effects in the cardiovascular, immunological, central nervous, and skeletal tissue systems. Still, despite intense investigation, the multiple and often perplexing roles of ERs retain significant attention. In the skeleton, this in part derives from apparently opposing effects by ER agonists on bone growth versus bone remodeling, and in younger versus older individuals. The complexity associated with ER activation can also derive from their interactions with other hormone and growth factor systems, and their direct and indirect effects on gene expression. We propose that part of this complexity results from essential interactions between ERs and other transcription factors, each with their own biochemical and molecular intricacies. Solving some of the many questions that persist may help to achieve better, or better directed, use of agents that can drive ER activation in focused and possibly tissue restricted ways.

Repositioning chloroquine and metformin to eliminate cancer stem cell traits in pre-malignant lesions

Ideal oncology drugs would be curative after a short treatment course if they could eliminate epithelium-originated carcinomas at their non-invasive, pre-malignant stages. Such ideal molecules, which are expected to molecularly abrogate all the instrumental mechanisms acquired by migrating cancer stem cells (CSCs) to by-pass tumour suppressor barriers, might already exist. We here illustrate how system biology strategies for repositioning existing FDA-approved drugs may accelerate our therapeutic capacity to eliminate CSC traits in pre-invasive intraepithelial neoplasias. First, we describe a signalling network signature that overrides bioenergetics stress- and oncogene-induced senescence (OIS) phenomena in CSCs residing at pre-invasive lesions. Second, we functionally map the anti-malarial chloroquine and the anti-diabetic metformin ("old drugs") to their recently recognized CSC targets ("new uses") within the network. By discussing the preclinical efficacy of chloroquine and metformin to inhibiting the genesis and self-renewal of CSCs we finally underscore the expected translational impact of the "old drugs-new uses" repurposing strategy to open a new CSC-targeted chemoprevention era.

Metabolic syndrome, central obesity and insulin resistance are associated with adverse pathological features in postmenopausal breast cancer

AIMS

Obesity is associated with both an increased risk of postmenopausal breast cancer and increased mortality rates. The mechanism is unclear, and central (visceral) obesity, insulin resistance, altered sex steroids and altered adipokines are mooted as possible factors. These features may cluster in the so-called metabolic syndrome. The relevance of metabolic syndrome to the biology of breast cancer is unknown, and this was the focus of the present study.

MATERIALS AND METHODS

All postmenopausal women with newly diagnosed breast cancer (n=105) were recruited. A detailed clinical history was carried out, as well as a body composition analysis, metabolic screen and measurement of adipokines and inflammatory markers.

RESULTS

The median age was 68 years (40-94 years) and the mean body mass index was 28.3+/-5.2 kg/m2, with 87% of patients centrally obese. Metabolic syndrome was diagnosed in 39% of patients, and was significantly associated with central obesity (P<0.005) and increased inflammation, with C-reactive protein levels doubling in metabolic syndrome patients compared with non-metabolic syndrome patients (10.3 vs 5.8 mg/l; P=0.084). Patients with a later pathological stage (II-IV) were significantly more likely to be obese (P=0.007), centrally obese (P=0.009), hyperglycaemic (P=0.047) and hyperinsulinaemic (P=0.026); 51% had metabolic syndrome compared with 12% for early stage disease. Patients with node-positive disease were significantly more likely to be hyperinsulaemic (P=0.030) and have metabolic syndrome (P=0.028) than patients with node-negative disease.

DISCUSSION

The data suggest that metabolic syndrome and central obesity are common in postmenopausal breast cancer patients, and that metabolic syndrome may be associated with a more aggressive tumour biology.

Rapid estradiol/ERalpha signaling enhances aromatase enzymatic activity in breast cancer cells

In situ estrogen production by aromatase conversion from androgens plays an important role in breast tumor promotion. Here, we show that 17beta-estradiol (E2) can rapidly enhance aromatase enzymatic activity through an increase of aromatase protein phosphorylation in breast cancer cell lines. In vivo labeling experiments and site-directed mutagenesis studies demonstrated that phosphorylation of the 361-tyrosine residue is crucial in the up-regulation of aromatase activity under E2 exposure. Our results demonstrated a direct involvement of nonreceptor tyrosine-kinase c-Src in E2-stimulated aromatase activity because inhibition of its signaling abrogated the up-regulatory effects induced by E2 on aromatase activity as well as phosphorylation of aromatase protein. In addition, from our data it emerges that aromatase is a target of cross talk between growth factor receptors and estrogen receptor alpha signaling. These findings show, for the first time, that tyrosine phosphorylation processes play a key role in the rapid changes induced by E2 in aromatase enzymatic activity, revealing the existence of a short nongenomic autocrine loop between E2 and aromatase in breast cancer cells.

[Obesity and cancer]

Obesity which is now well recognized as a public health problem increases the risk of developing cancers. Some systematic review and meta-analyses assessed the strength of associations between body mass index and common cancers such as breast, endometrial, colon and adenocarcinoma of oesophagus. The causal mechanisms remain unexplained. However, epidemiological data and animal models have provided some evidence that hormonal alteration linked to obesity, such as hyperinsulinism, high insulin-like growth factor (IGF-1) levels or biodisponibility, low adiponectin serum level and high oestradiol serum level resulting from an enhanced aromatase activity may have mitogenic and antiapoptotic effects. The inflammation associated with visceral adiposity is another factor which promotes cancer. To date, there are no convincing data that weight loss could improve the prognosis of treated neoplasia. However, a regular physical activity and a limited caloric intake are probably safe in healthy subject to prevent cancer and also in cancer survivors.

What clinicians need to know about antioestrogen resistance in breast cancer therapy

Tamoxifen is the drug most used for early breast cancer treatment in oestrogen receptor (ER) positive patients. Unfortunately, despite high ER tumour levels in a tumour, resistance to endocrine therapy, either de novo or acquired after prolonged treatment, can occur. In this review, we will try to summarise the postulated mechanisms of hormonal-resistance, namely, the role of co-regulators and the crosstalk between the HER-2, IGF-IR, Cox-2 and ER pathways. Other predictive markers of tamoxifen-resistance/response, such as cyclin E and UPA/PAI-1, are also discussed.

Risk factors for breast carcinoma in situ versus invasive breast cancer in a prospective study of pre- and post-menopausal women

Risk factors for breast carcinoma in situ and invasive breast cancer were compared using data from 61,844 women (61% post-menopausal) with no prior breast cancer and at least one screening mammogram between April 1, 1996 and June 30, 2001. The women were followed until a subsequent mammogram before July 1, 2001, or a benign biopsy or breast cancer diagnosis before June 30, 2002. A total of 1,191 breast cancers (300 in situ and 891 invasive) were diagnosed during an average follow-up of 3.1 years. Multivariate Cox regression models were used to estimate the relative risks (RR) of in situ and invasive cancer associated with family history of breast cancer, age at first childbirth or nulliparity, post-menopausal hormone use, body mass index (BMI), and mammographic breast density. Separate analyses were done for pre- and post-menopausal women. BMI was unrelated to risk of in situ cancer regardless of menopausal status, but was associated with an increased risk of invasive cancer in post-menopausal women (RR = 1.9 for BMI > or = 30 vs. BMI < 22, 95% confidence interval 1.4-2.5). Later childbearing and nulliparity were more strongly associated with in situ than invasive cancer in pre-menopausal women. Post-menopausal hormone use was more strongly associated with invasive disease. RR associated with family history and breast density were similar for in situ cancer and invasive cancer. Results indicating that BMI is related to post-menopausal invasive cancers but unrelated to in situ cancers are consistent with the hypothesis that concomitants of obesity activate proliferation.

Apolipoprotein E and the Risk of Breast Cancer in African-American and Non-Hispanic White Women

The apolipoprotein genetic polymorphism (APO E) is part of a broader paradigm, highlighting the role of gene-environment interactions as risk factors for human diseases such as cardiovascular disease, Alzheimer’s disease, dementia, atherosclerosis, multiple sclerosis, peripheral artery disease, diabetes, stroke, and most recently, cancer. APO E, a normal constituent of very-low-density lipoproteins and high-density lipoproteins, is involved in many functions, including lipid metabolism, cholesterol transport, tissue repair, immune response and regulation, as well as cell growth and differentiation. The location, frequency and functional effects of this gene have been reviewed elsewhere in terms of cardiovascular disease, Alzheimer’s disease, neuromuscular disease, multiple sclerosis, stroke and diabetes. However, while the majority of studies have examined the significance of APO E as a molecular marker for a variety of diseases in multiethnic populations, few evaluate its role as a putative marker of cancer susceptibility. Fewer explore the importance of APO E on the risk of breast cancer, although some report an association. None have been designed to study its relevance as a marker of breast cancer risk in multiethnic populations. The purpose of this review was to evaluate the association between APO E and the risk for breast cancer in non-Hispanic white and African-American women.

N-3 fatty acids and lipid peroxidation in breast cancer inhibition

Long-chain n-3 fatty acids (FA) consistently inhibit the growth of human breast cancer (BC) cells both in culture and in grafts in immunosuppressed mice. Large cohort studies have, however, failed to confirm a protective effect for fish oils rich in n-3 FA against BC risk. The present review examines new evidence on biological mechanisms which may be involved in the inhibition of mammary carcinogenesis by long-chain n-3 FA, focusing on an apoptotic effect by its lipid peroxidation products. Dietary intake of n-3 FA leads to their incorporation into cell membrane lipids. Increased apoptosis in human BC cells following exposure to long-chain n-3 FA such as eicosapentaenoic and docosahexaenoic acids is generally ascribed to their inhibition of cyclooxygenase 2 which promotes mammary carcinogenesis. In addition however, long-chain n-3 FA are particularly likely to activate peroxisome proliferator-activated receptor (PPAR)-gamma, a key regulator of lipid metabolism but also capable of modulating proliferative activity in a variety of cells including mammary cells. Expression of PPAR-gamma in the nucleus is activated by second messengers such as J series prostaglandins and the latter have been shown to cause apoptosis in vivo in explants of human BC cells in immunosuppressed mice. In mammary tumours, it is observed that long-chain FA not only increase apoptosis, but also increase lipid peroxidation, and the apoptotic effect can be reversed by antioxidants. The rationale for use of n-3 FA dietary supplements in counteracting BC progression needs to be tested clinically in a phase 2 pilot study, while at the same time, the effect on whole-body lipid peroxidation needs to be monitored. Dietary supplements of fish oil rich in n-3 FA are proposed for premenopausal women over the age of 40 years who are shown to be at increased BC risk. Biological markers in breast tissue of BC progression will be monitored, and observed changes related to serial plasma levels of isoprostanes as a measure of whole-body lipid peroxidation.