Abstract P1-02-07: Breast density, metabolic syndrome and body composition in breast cancer

Background- The metabolic syndrome (MetS) is prevalent among post-menopausal breast cancer patients and is associated with increased breast cancer risk. Mammographic breast density (BD) is also positively associated with increased breast cancer risk. The relationship between MetS and mammographic BD is unclear and requires further investigation.

Aim- The aim of this study was to examine the relationship between the MetS and its component features with breast density.

Methods - 112 post-menopausal women with breast cancer were recruited. Body composition (Body Mass Index (BMI), waist circumference (WC)) was measured objectively in participants prior to surgery. Metabolic profiles were measured in blood taken from participants prior to surgery. MetS was defined according to the International Diabetes Federation (IDF) criteria. BD was classified according to the Breast Imaging Reporting and Data System (BI-RADS). Participants were categorised into those with 'Dense' (BI-RADS score 3 or 4) or 'Less Dense' (BI-RADS score 1 or 2) breasts. Group means were compared using unpaired t-tests for parametric or Mann Whitney tests for non-parametric data. Categorical data was analysed using Fisher's exact test or Chi squared test as appropriate.

Results - An inverse relationship was observed between measures of adiposity and BD. Participants with 'dense' (BI-RADS 3/4) breasts had significantly lower BMI(p=0.0034), waist circumference(p=0.0007), systolic blood pressure(p= 0.03), circulating insulin level(p=0.009) and glycated haemoglobin(p=0.008) than those with 'less dense' (BI-RADS 1/2) breasts. HDL was significantly higher in those with 'dense' versus those with 'less dense' breasts(p= 0.03). participants with 'less dense' breasts were significantly more likely to be insulin resistant (HOMA-IR ≥2) than those with 'dense breasts' (50.6% versus 20% respectively); p=0.01.

Other components of the MetS (Serum triglycerides, glucose and diastolic blood pressure) did not differ significantly between participants with 'dense' and 'less dense' breasts. No differences in overall survival were observed between participants with 'Dense' versus those with 'Less Dense' breasts (P=0.93).

Conclusion - Although both MetS and BD are positively associated with breast cancer risk; it is unlikely that the MetS is related to an increase in breast cancer risk through a mechanism involving BD. Further work on this study is currently underway and will involve adjusting for potential confounders including age and BMI as well as examining the relationship between MetS and BD in pre-menopausal breast cancer patients.

Citation Format: Shokuhi P, McGarrigle SA, Sullivan CJ, Boyle T, Al-azawi D, O'Keeffe S, Kennedy J, Connolly EM. Breast density, metabolic syndrome and body composition in breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-02-07.

Abstract P3-09-02: Unhealthy lifestyle patterns are prevalent in unaffected BRCA mutation carriers & are associated with increased oxidative stress and telomere length alterations

The lifetime-risk of breast-cancer is greatly increased in women carrying a deleterious mutation in the BRCA1 or BRCA2 genes. Recently, there has been increased penetrance of BRCA1 and BRCA2 mutations which may be due to lifestyle influences.

There is a need to identify approaches to reduce the penetrance of BRCA 1/2 mutations. Understanding how modifiable lifestyle-factors affect cancer-risk in BRCA-mutation carriers may have implications for risk-reduction in this group. At the molecular level, oxidative-stress and telomere dysfunction are early events in cancer development and these processes may be considered surrogate markers of cancer-risk. It has been reported that BRCA-mutation carriers are more susceptible to these pro-carcinogenic processes that non-carriers.

The aim of this pilot study was to objectively measure lifestyle factors in unaffected BRCA-mutation carriers and to assess the impact of these lifestyle-factors on oxidative-stress profiles and telomere length.

Participants (n=75) were recruited from breast-cancer family-risk clinics and cancer-genetics clinics. Body-composition (BMI, waist-circumference), metabolic profiles and physical-activity (triaxial accelerometry) were measured for each participant. Serum levels of the oxidative-stress markers 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-DG) and 4-hydroxynonenal (4-HNE) were measured in a subset of participants (n=30) by ELISA. Telomere length was measured in a subset of participants (n=30) by quantitative PCR (qPCR).

Participants demonstrated poor adherence to physical-activity guidelines with 94% not reaching physical-activity levels recommended by the American College of Sports Medicine. The majority of participants were overweight (39%) or obese (32%) with 73% exhibiting abdominal obesity. 21% of participants had the metabolic syndrome (MetS) at the time of study enrolment with the majority of participants (80%) presenting with at least one feature of the MetS. Circulating levels of 8-oxo-DG did not appear to be affected by body composition or MetS status, however, serum levels of the lipid peroxidation marker 4-HNE were significantly higher in participants with the MetS (p < 0.0001). Correlation of serum 4-HNE levels with individual features of the MetS and related parameters revealed significant direct correlations with waist circumference (p = 0.02), number of features of MetS (p = 0.0007), insulin (p = 0.02) insulin resistance score (HOMA-IR) (p = 0.01), HBA1c (p = 0.006), glucose (p = 0.048) and triglycerides (p <0.0001). Age-adjusted telomere length was not influenced by anthropometric measurements or MetS status in this group. Moderate physical activity levels were inversely associated with age-adjusted telomere length; particularly, among post-menopausal participants (p =0.009).

This work has provided compelling evidence that in this cohort of BRCA-mutation carriers, unhealthy lifestyle-patterns are prevalent. In addition, these results suggest that the potential may exist to modify pro-carcinogenic processes in this cohort by modifying physical activity levels and targeting the metabolic syndrome and its component features lifestyle interventions and/or medication.The lifetime-risk of breast-cancer is greatly increased in women carrying a deleterious mutation in the BRCA1 or BRCA2 genes. Recently, there has been increased penetrance of BRCA1 and BRCA2 mutations which may be due to lifestyle influences.

There is a need to identify approaches to reduce the penetrance of BRCA 1/2 mutations. Understanding how modifiable lifestyle-factors affect cancer-risk in BRCA-mutation carriers may have implications for risk-reduction in this group. At the molecular level, oxidative-stress and telomere dysfunction are early events in cancer development and these processes may be considered surrogate markers of cancer-risk. It has been reported that BRCA-mutation carriers are more susceptible to these pro-carcinogenic processes that non-carriers.

The aim of this pilot study was to objectively measure lifestyle factors in unaffected BRCA-mutation carriers and to assess the impact of these lifestyle-factors on oxidative-stress profiles and telomere length.

Participants (n=75) were recruited from breast-cancer family-risk clinics and cancer-genetics clinics. Body-composition (BMI, waist-circumference), metabolic profiles and physical-activity (triaxial accelerometry) were measured for each participant. Serum levels of the oxidative-stress markers 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-DG) and 4-hydroxynonenal (4-HNE) were measured in a subset of participants (n=30) by ELISA. Telomere length was measured in a subset of participants (n=30) by quantitative PCR (qPCR).

Participants demonstrated poor adherence to physical-activity guidelines with 94% not reaching physical-activity levels recommended by the American College of Sports Medicine. The majority of participants were overweight (39%) or obese (32%) with 73% exhibiting abdominal obesity. 21% of participants had the metabolic syndrome (MetS) at the time of study enrolment with the majority of participants (80%) presenting with at least one feature of the MetS. Circulating levels of 8-oxo-DG did not appear to be affected by body composition or MetS status, however, serum levels of the lipid peroxidation marker 4-HNE were significantly higher in participants with the MetS (p < 0.0001). Correlation of serum 4-HNE levels with individual features of the MetS and related parameters revealed significant direct correlations with waist circumference (p = 0.02), number of features of MetS (p = 0.0007), insulin (p = 0.02) insulin resistance score (HOMA-IR) (p = 0.01), HBA1c (p = 0.006), glucose (p = 0.048) and triglycerides (p <0.0001). Age-adjusted telomere length was not influenced by anthropometric measurements or MetS status in this group. Moderate physical activity levels were inversely associated with age-adjusted telomere length; particularly, among post-menopausal participants (p =0.009).

This work has provided compelling evidence that in this cohort of BRCA-mutation carriers, unhealthy lifestyle-patterns are prevalent. In addition, these results suggest that the potential may exist to modify pro-carcinogenic processes in this cohort by modifying physical activity levels and targeting the metabolic syndrome and its component features lifestyle interventions and/or medication.

Citation Format: McGarrigle SA, Guinan EM, Hussey J, O'Sullivan J, Boyle T, Hanhauser Y, Al-azawi D, Kennedy MJ, Gallagher DJ, Connolly EM. Unhealthy lifestyle patterns are prevalent in unaffected BRCA mutation carriers & are associated with increased oxidative stress and telomere length alterations [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-09-02.

Changes in mitochondrial stability during the progression of the Barrett's esophagus disease sequence

Background

Barrett’s esophagus follows the classic step-wise progression of metaplasia-dysplasia-adenocarcinoma. While Barrett’s esophagus is a leading known risk factor for esophageal adenocarcinoma, the pathogenesis of this disease sequence is poorly understood. Mitochondria are highly susceptible to mutations due to high levels of reactive oxygen species (ROS) coupled with low levels of DNA repair. The timing and levels of mitochondria instability and dysfunction across the Barrett’s disease progression is under studied.

Methods

Using an in-vitro model representing the Barrett’s esophagus disease sequence of normal squamous epithelium (HET1A), metaplasia (QH), dysplasia (Go), and esophageal adenocarcinoma (OE33), random mitochondrial mutations, deletions and surrogate markers of mitochondrial function were assessed. In-vivo and ex-vivo tissues were also assessed for instability profiles.

Results

Barrett’s metaplastic cells demonstrated increased levels of ROS (p < 0.005) and increased levels of random mitochondrial mutations (p < 0.05) compared with all other stages of the Barrett’s disease sequence in-vitro. Using patient in-vivo samples, Barrett’s metaplasia tissue demonstrated significantly increased levels of random mitochondrial deletions (p = 0.043) compared with esophageal adenocarcinoma tissue, along with increased expression of cytoglobin (CYGB) (p < 0.05), a gene linked to oxidative stress, compared with all other points across the disease sequence. Using ex-vivo Barrett’s metaplastic and matched normal patient tissue explants, higher levels of cytochrome c (p = 0.003), SMAC/Diablo (p = 0.008) and four inflammatory cytokines (all p values <0.05) were secreted from Barrett’s metaplastic tissue compared with matched normal squamous epithelium.

Conclusions

We have demonstrated that increased mitochondrial instability and markers of cellular and mitochondrial stress are early events in the Barrett’s disease sequence.

Abstract P2-09-16: Pre-clinical evaluation of novel anti-angiogenic agents as breast cancer therapeutics

Background

There is a need to develop novel drugs that will improve survival in breast cancer patients. Angiogenesis is essential for breast tumour progression. To date, the most promising approach to inhibit angiogenesis in breast cancer patients has been the drug bevacizumab which targets the pro-angiogenic factor Vascular Endothelial Growth Factor (VEGF). Recently, there has been controversy regarding the efficacy of bevacizumab for breast cancer treatment. In clinical trials, bevacizumab failed to establish an overall-survival benefit and was associated with serious toxicities. This resulted in the FDA revoking approval for the drug for the first line treatment of advanced breast cancer. Due to this uncertainty surrounding the efficacy of bevacizumab for the treatment of breast cancer it is clear that there is a clinical need for more effective novel anti-angiogenic drugs with better toxicity profiles for the treatment of breast cancer.

Aim

This study aimed to identify novel small-molecule anti-angiogenic agents with therapeutic potential in human breast cancer.

Methods

Compounds with physiochemical properties consistent with drug-like compounds were screened for anti-angiogenic activity by high-throughput screening involving zebrafish larvae. Human breast tumour explants were treated with the lead compound and secretion of angiogenic factors was assessed by ELISA.

Results

We have identified a novel small-molecule agent ‘SMG1’ that significantly inhibited inter-segmental blood-vessel development in zebrafish and showed no toxicity. Treatment of breast tumour explants with SMG1 significantly inhibited secretion of the potent pro-angiogenic cytokine VEGF (p = 0.01). Furthermore, SMG1 inhibited VEGF secretion more than the standard targeted breast cancer therapies tamoxifen and Herceptin® which have been reported to inhibit angiogenesis.

Conclusion

Continuing pre-clinical work will determine if SMG1 has potential as a therapeutic agent for human breast cancer.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-09-16.

Abstract P6-01-02: Adipose tissue from breast cancer patients with the metabolic syndrome promotes proliferation and invasion of tumor cells and influences expression of genes involved in carcinogenesis

Background: Obesity is a public health issue of global proportions and is recognised as a risk factor for post-menopausal breast cancer. Similarly, the metabolic syndrome (MetS) is recognised as a high risk state for cancer in general. Previously we have shown that the MetS is common in postmenopausal breast cancer patients and is associated with a more aggressive tumor biology. However, the molecular mechanisms by which obesity and/or the MetS promote breast cancer remain unclear. Adipose tissue, including mammary fat, is a functionally active endocrine organ. The aims of this study were to determine whether factors secreted by mammary adipose tissue could affect tumor cell biology and to assess the effect of the MetS on this adipose depot and its subsequent effect on tumor cells.

Methods: Adipose tissue from fresh mastectomy specimens was cultured in serum free media for 72 h to produce adipose conditioned media (ACM). MCF-7 and MDA-MB 231 cell lines were treated with ACM for 24–48 h. Tumor cell function was then assessed by measuring cell proliferation (BrDU assay) and cell invasion. In addition, expression of 84 genes implicated in pathways involved in carcinogenesis was examined in these cell lines following ACM treatment, using quantitative PCR arrays.

Results: In the estrogen receptor (ER) positive MCF-7 cell line, ACM from MetS breast cancer patients promoted significantly greater proliferation compared to ACM from normal weight patients (203.6 ± 34.23 vs 136.8 ± 11.58%, p = 0.022). Similarly, ACM from MetS patients significantly increased invasion of MCF-7 cells compared to ACM from normal weight patients (153.4 ± 6.027 vs 126.3 ± 6.03% RFU, p = 0.006). No differences in cell proliferation or invasion between cells treated with ACM from MetS patients compared to ACM from normal weight patients were found in the ER negative MDA-MB-231 cell line. Treatment of MCF-7 cells with ACM from MetS patients resulted in significant alterations (&gt;2 fold up/down regulation) in expression of 11 genes involved in carcinogenesis. Primarily, genes implicated in invasion/metastasis and adhesion were differentially expressed between ACM-treated cells and cells treated with control media. On the other hand, when MDA-MB-231 cells were treated with ACM from the same patients only one gene, SERPIN B5 was significantly up-regulated &gt; 2 fold.

Conclusions: These data demonstrate that factors secreted from mammary adipose tissue from metabolically unhealthy patients promote proliferation and invasion of ER positive tumor cells and influence expression of genes involved in carcinogenesis in these cells. These effects were not observed in ER negative tumor cells suggesting that they may be mediated, at least in part by the estrogen receptor. These results have provided insight into how mammary adipose tissue may act via a paracrine mechanism to influence aspects of carcinogenesis and into how the metabolic syndrome may modulate this.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-01-02.

Pro-inflammatory and tumour proliferative properties of excess visceral adipose tissue

Obesity has been associated with increased incidence and mortality of oesophageal and colorectal adenocarcinoma. Excess central adiposity may drive this association through an altered inflammatory milieu. Utilising a unique adipose tissue bioresource we aimed to determine the pro-tumour properties of visceral adipose tissue. Comparing subcutaneous and visceral adipose tissue depots, we observed significantly higher levels of VEGF and IL-6, along with significantly higher proportions of CD8(+) T cells and NKT cells in visceral adipose tissue. Significantly higher levels of VEGF were observed in the conditioned media from visceral adipose tissue of centrally obese compared to non-obese patients. We also report a significant increase in oesophageal and colorectal tumour cell proliferation following culture with conditioned media from visceral adipose tissue of centrally obese patients. Neutralising VEGF in the conditioned media significantly decreased tumour cell proliferation. This novel report highlights a potential mechanism whereby visceral adipose tissue from centrally obese cancer patients may drive tumour progression.