Awareness and Candidacy for Endocrine Prevention and Risk Reducing Mastectomy in Unaffected High-Risk Women Referred for Breast Cancer Risk Assessment

INTRODUCTION

Primary prevention of breast cancer in women at elevated risk includes several strategies such as endocrine prevention and risk-reducing mastectomy (RRM). The objective of this study was to evaluate awareness of different preventive strategies across high-risk subgroups.

PATIENTS AND METHODS

Women referred for high risk evaluation between 2020 and 2023 completed an initial risk-assessment questionnaire that included questions around perceived lifetime risk and consideration of preventive strategies. One-way analysis of variance (ANOVA) and chi-squared tests were used to compare differences across different high-risk subgroups.

RESULTS

482 women with a median age of 43 years (20-79 years) met inclusion criteria; 183 (38.0%) germline pathogenic variant carriers (GPV), 90 (18.7%) with high-risk lesions (HRL) on breast biopsy, and 209 (43.4%) with strong family history (FH) without a known genetic predisposition. Most high-risk women reported that they had considered increased screening and surveillance (83.7%) and lifestyle strategies (80.6%), while fewer patients had considered RRM (39.8%) and endocrine prevention (27.0%). Prior to initial consultation, RRM was more commonly considered in GPV carriers (59.4%) relative to those with HRL (33.3%) or strong FH (26.3%, p < 0.001). Based on current guidelines, 206 (43%) patients were deemed eligible for endocrine prevention, including 80.5% with HRL and 39.0% with strong FH. Prior consideration of endocrine prevention was highest in patients with HRL and significantly lower in those with strong FH (47.2% HRL versus 31.1% GPV versus 18.7% FH, p = 0.001).

CONCLUSIONS

Endocrine prevention is the least considered preventive option for high-risk women, despite eligibility in a significant proportion of those presenting with HRL or strong FH.

Utilizing metformin to prevent metabolic syndrome due to androgen deprivation therapy (ADT): a randomized phase II study of metformin in non-diabetic men initiating ADT for advanced prostate cancer

BACKGROUND

Androgen deprivation therapy (ADT) can lead to metabolic syndrome (MS) and is implicated in ADT-resistance. Metformin showed antineoplastic activity through mTOR inhibition secondary AMPK-activation.

MATERIALS AND METHODS

To investigate whether metformin mitigated ADT-related MS, we conducted a randomized double-blind phase II trial of metformin 500 mg TID or placebo in non-diabetic patients with biochemically-relapsed or advanced PC due for ADT. Fasting serum glucose, insulin, PSA, metformin, weight and waist circumference (WC) were measured at baseline, week 12 and 28. The primary endpoint was a group of MS metrics. Secondary endpoints include PSA response, safety, serum metformin concentrations and analysis of downstream an mTOR target, phospho-S6-kinase.

RESULTS

36 men were randomized to either metformin or placebo. Mean age was 68.4. Mean weight, WC and insulin levels increased in both arms. At week 12 and 28, no statistical differences in weight, WC or insulin were observed in either arm. No significant difference in percentage of patients with PSA <0.2 at week 28 between metformin (45.5%) vs. placebo (46.7%). Analysis in the metformin-arm showed variable down-regulation of phospho-S6 kinase.

CONCLUSIONS

In our small study, metformin added to ADT did not show a reduced risk of ADT-related MS or differences in PSA response.

Obesity promotes breast epithelium DNA damage in women carrying a germline mutation in BRCA1 or BRCA2

Obesity, defined as a body mass index (BMI) ≥ 30, is an established risk factor for breast cancer among women in the general population after menopause. Whether elevated BMI is a risk factor for women with a germline mutation in BRCA1 or BRCA2 is less clear because of inconsistent findings from epidemiological studies and a lack of mechanistic studies in this population. Here, we show that DNA damage in normal breast epithelia of women carrying a BRCA mutation is positively correlated with BMI and with biomarkers of metabolic dysfunction. In addition, RNA sequencing showed obesity-associated alterations to the breast adipose microenvironment of BRCA mutation carriers, including activation of estrogen biosynthesis, which affected neighboring breast epithelial cells. In breast tissue explants cultured from women carrying a BRCA mutation, we found that blockade of estrogen biosynthesis or estrogen receptor activity decreased DNA damage. Additional obesity-associated factors, including leptin and insulin, increased DNA damage in human BRCA heterozygous epithelial cells, and inhibiting the signaling of these factors with a leptin-neutralizing antibody or PI3K inhibitor, respectively, decreased DNA damage. Furthermore, we show that increased adiposity was associated with mammary gland DNA damage and increased penetrance of mammary tumors in Brca1+/- mice. Overall, our results provide mechanistic evidence in support of a link between elevated BMI and breast cancer development in BRCA mutation carriers. This suggests that maintaining a lower body weight or pharmacologically targeting estrogen or metabolic dysfunction may reduce the risk of breast cancer in this population.

Prospective associations of hemoglobin A1c and c-peptide with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort

Self-reported type 2 diabetes mellitus (T2DM) is a risk factor for many cancers, suggesting its pathology relates to carcinogenesis. We conducted a case-cohort study to examine associations of hemoglobin A1c (HbA1c) and c-peptide with cancers associated with self-reported T2DM. This study was drawn from a prospective cohort of 32,383 women and men who provided blood specimens at baseline: c-peptide and HbA1c were assessed in 3,000 randomly selected participants who were cancer-free-at-baseline and an additional 2,281 participants who were cancer-free-at-baseline and subsequently diagnosed with incident colorectal, liver, pancreatic, female breast, endometrial, ovarian, bladder, or kidney cancers. Weighted-Cox regression models estimated hazards ratios (HRs) and 95% confidence intervals (CI), adjusted for covariates. C-peptide was associated with higher risk of liver cancer (per standard deviation (SD) HR: 1.80; 95%CI: 1.32-2.46). HbA1c was associated with higher risk of pancreatic cancer (per SD HR: 1.21 95%CI 1.05-1.40) and with some suggestion of higher risks for all-cancers-of-interest (per SD HR: 1.05; 95%CI: 0.99-1.11) and colorectal (per SD HR: 1.09; 95%CI: 0.98-1.20), ovarian (per SD HR: 1.18; 95%CI 0.96-1.45) and bladder (per SD HR: 1.08; 95%CI 0.96-1.21) cancers. Compared to no self-reported T2DM and HbA1c <6.5% (reference group), self-reported T2DM and HbA1c <6.5% (i.e., T2DM in good glycemic control) was not associated with risk of colorectal cancer, whereas it was associated with higher risks of all-cancers-of-interest combined (HR: 1.28; 95%CI: 1.01-1.62), especially for breast and endometrial cancers. Additional large, prospective studies are needed to further explore the roles of hyperglycemia, hyperinsulinemia, and related metabolic traits with T2DM-associated cancers to better understand the mechanisms underlying the self-reported T2DM-cancer association and to identify persons at higher cancer risk.

Metformin-induced reductions in tumor growth involves modulation of the gut microbiome

Background/Purpose

Type 2 diabetes and obesity increase the risk of developing colorectal cancer. Metformin may reduce colorectal cancer but the mechanisms mediating this effect remain unclear. In mice and humans, a high-fat diet (HFD), obesity and metformin are known to alter the gut microbiome but whether this is important for influencing tumor growth is not known.

Methods

Mice with syngeneic MC38 colon adenocarcinomas were treated with metformin or feces obtained from control or metformin treated mice.

Results

We find that compared to chow-fed controls, tumor growth is increased when mice are fed a HFD and that this acceleration of tumor growth can be partially recapitulated through transfer of the fecal microbiome or in vitro treatment of cells with fecal filtrates from HFD-fed animals. Treatment of HFD-fed mice with orally ingested, but not intraperitoneally injected, metformin suppresses tumor growth and increases the expression of short-chain fatty acid (SCFA)-producing microbes Alistipes, Lachnospiraceae and Ruminococcaceae. The transfer of the gut microbiome from mice treated orally with metformin to drug naïve, conventionalized HFD-fed mice increases circulating propionate and butyrate, reduces tumor proliferation, and suppresses the expression of sterol response element binding protein (SREBP) gene targets in the tumor.

Conclusion

These data indicate that in obese mice fed a HFD, metformin reduces tumor burden through changes in the gut microbiome.

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Oral but not intraperitoneal injection of metformin is associated with changes in the gut microbiome and reductions in MC38 tumor cell growth in mice fed a high-fat diet.

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Transferring feces from mice treated with oral metformin into metformin naïve mice inhibits tumor growth independently of changes in body mass, blood glucose or serum insulin.

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Metformin fecal transfers to metformin naïve mice leads to increased abundance of short chain fatty acid producing microbes.

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Metformin fecal transfers reprogram tumor metabolism reducing the expression of SREBP and cholesterol synthesis genes.

Abstract P2-06-03: Obesity is associated with DNA damage in the breast epithelium of BRCA1 and BRCA2 mutation carriers: A role for estrogens & strategies for prevention

Background: Elevated bodyweight is a risk factor for breast cancer development in women who carry a mutation in the DNA repair enzymes BRCA1 and BRCA2. However, the mechanistic basis for this association is unknown. Breast adipose tissue undergoes significant changes in the setting of weight gain and obesity, including elevation in aromatase expression which leads to the increased biosynthesis of estrogens. Given that estrogens and estrogen metabolites have known pro-proliferative and genotoxic effects, we hypothesized that in BRCA1/2 mutation carriers, obesity may be positively associated with breast epithelial cell DNA damage, thereby increasing the risk of tumorigenesis. Furthermore, we examined the impact of inhibiting estrogen signaling or production on breast epithelium DNA damage in BRCA1/2 mutation carriers. Methods: Tissue microarrays were generated from non-cancerous breast tissue derived from 72 women carrying a mutation in BRCA1 or BRCA2 with known body mass index (BMI, kg/m2). Breast epithelium DNA damage was quantified by immunofluorescence (IF) staining of the DNA damage marker γH2AX. RNA-Seq was performed on breast organoids to assess differences in gene expression in relation to BMI. Associations between DNA damage and biomarkers of estrogen biosynthesis and bioavailability, including aromatase expression in the breast and circulating steroid hormone binding globulin (SHBG), were also evaluated. To explore the effect of blocking estrogen signaling or production on DNA damage, non-tumorous breast tissue explants from BRCA1/2 mutation carriers were cultured with fulvestrant, an estrogen receptor degrader, or metformin, an anti-diabetic drug that also reduces aromatase expression in the breast. Breast epithelial cell DNA damage was measured in control vs treated explants by γH2AX IF staining after 24 hours of treatment. Results: BMI was positively correlated with DNA damage in the breast epithelium of BRCA1/2 mutation carriers. Upstream analysis of gene expression in organoids derived from women with a BMI ≥ 30 compared to &lt;25, revealed activation of estrogen signaling. Further supporting a contribution of locally-derived and circulating estrogens to obesity-related DNA damage, breast aromatase expression was found to be positively correlated with DNA damage while circulating SHBG levels showed a negative correlation. Targeting estrogen signaling with fulvestrant significantly reduced breast epithelium DNA damage in breast explants from women carrying a mutation in either BRCA1 or BRCA2. Interestingly, metformin, also caused a significant reduction in DNA damage in breast explants. Conclusion: These data provide mechanistic evidence for the link between obesity and breast cancer in BRCA1 and BRCA2 mutation carriers through identification of a positive association between BMI and breast epithelial cell DNA damage. Importantly, these studies demonstrate that fulvestrant and metformin, drugs already approved for clinical use, decrease breast epithelial cell DNA damage. Further studies are warranted to determine whether targeting estrogens or use of metformin may be effective risk reduction strategies in BRCA1/2 mutation carriers with excess bodyweight who are at high risk for breast cancer development and currently have limited options for prevention beyond surgical intervention. Support: NIH R01CA215797, NIH F31CA236306, Anne Moore Breast Cancer Research Fund

Citation Format: Priya Bhardwaj, Neil M. Iyengar, Sofya Oshchepkova, Phoebe Piloco, Rohan Bareja, Olivier Elemento, Dilip D. Giri, Michael Pollak, Monica Morrow, Jason A. Spector, Kristy A. Brown. Obesity is associated with DNA damage in the breast epithelium of BRCA1 and BRCA2 mutation carriers: A role for estrogens & strategies for prevention [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-06-03.

Abstract PD7-07: Surgical management and contralateral breast cancer risk in women with a history of radiation therapy for Hodgkin lymphoma: Results from a population-based cohort

Background: Women with a history of chest radiation for Hodgkin lymphoma are at an increased risk of developing breast cancer. Although mastectomy has historically been recommended for surgical treatment of breast cancers in women with prior radiation exposure, surgical management trends and contralateral breast cancer risk in this population remain undefined. Methods: We performed a population-based retrospective study using the Surveillance, Epidemiology, and End Results (SEER) database from 1990-2016. Our cohort included women who received radiation for Hodgkin lymphoma prior to 30 years old and were diagnosed with a subsequent breast cancer. We evaluated trends in local therapy including rates of breast conserving surgery (BCS) and mastectomy. In those undergoing unilateral surgery, the Kaplan-Meier method was used to estimate the 5- and 10-year cumulative incidence of contralateral breast cancer. Results: Our final cohort included 295 women with a median age of 22 years (range, 8-30 years) at Hodgkin lymphoma diagnosis, and 42 years (range, 22-65 years) at breast cancer diagnosis. Of these patients, 263 (89.2%) presented with unilateral breast cancer, while 32 (10.8%) presented with synchronous bilateral breast cancer. Overall, BCS was performed in 17.3% of patients and mastectomy was performed in 82.7%. In the 263 patients presenting with unilateral breast cancer, 50 (19.0%) underwent BCS and 213 (81.0%) underwent mastectomy. Subgroup analysis of mastectomy patients with surgical laterality information available demonstrated a 40.5% bilateral mastectomy rate. In the entire cohort, the 5-year incidence of contralateral breast cancer in women who underwent unilateral surgery was 9.4% (95% CI, 5.6-15.4), increasing to 20.2% (95% CI, 13.7-29.2) at 10-years of follow up. Hormone receptor status of the index breast cancer was not associated with significant differences in the incidence of contralateral breast cancer (p=0.13). Conclusions: Women with a history of prior chest radiation for Hodgkin Lymphoma with a diagnosis with breast cancer have a 10-year contralateral breast cancer risk of 20%. These findings support consideration of contralateral prophylactic mastectomy during surgical decision-making in this high-risk patient population.

Citation Format: Elisheva R Eisenberg, Anna Weiss, Ipshita Prakash, Sonia Skamene, Mark Basik, Jean Francois Boileau, Lissa Ajjamada, Michael Pollak, Stephanie M Wong. Surgical management and contralateral breast cancer risk in women with a history of radiation therapy for Hodgkin lymphoma: Results from a population-based cohort [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD7-07.

Circulating Insulin-Like Growth Factor 1-Related Biomarkers and Risk of Lethal Prostate Cancer

Background

Experimental and epidemiologic evidence supports the role of circulating insulin-like growth factor-1 (IGF-1) levels with the risk of prostate cancer. Most circulating IGF-1 is bound to specific binding proteins, and only about 5% circulates in a free form. We explored the relation of free IGF-1 and other components of the IGF system with lethal prostate cancer.

Methods

Using prospectively collected samples, we undertook a nested case-only analysis among 434 men with lethal prostate cancer and 524 men with indolent, nonlethal prostate cancer in the Physicians’ Health Study and the Health Professionals Follow-up Study. Prediagnostic plasma samples were assayed for free IGF-1 and total IGF-1, acid labile subunit, pregnancy-associated plasma protein A (PAPP-A), and intact and total IGF binding protein 4. We estimated odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the associations between IGF-1–related biomarkers and lethal prostate cancer using unconditional logistic regression models adjusted for age, height, and body mass index.

Results

Men in the highest quartile of PAPP-A levels had 42% higher odds of lethal prostate cancer (pooled adjusted OR = 1.42, 95% CI = 1.04 to 1.92) compared with men in the lowest 3 quartiles. There were no statistically significant differences in the other plasma analytes. The positive association between PAPP-A and lethal prostate cancer was present among men with intact PTEN but not among those with tumor PTEN loss (2-sided P_interaction = .001).

Conclusions

Our study provides suggestive evidence that among men who later develop prostate cancer, higher plasma PAPP-A levels measured prior to diagnosis are associated with increased risk of lethal compared with indolent disease.

Clinically Relevant Circulating Protein Biomarkers for Type 1 Diabetes: Evidence From a Two-Sample Mendelian Randomization Study

OBJECTIVE

To identify circulating proteins influencing type 1 diabetes susceptibility using Mendelian randomization (MR).

RESEARCH DESIGN AND METHODS

We used a large-scale two-sample MR study, using cis genetic determinants (protein quantitative trait loci [pQTL]) of up to 1,611 circulating proteins from five large genome-wide association studies, to screen for causal associations of these proteins with type 1 diabetes risk in 9,684 case subjects with type 1 diabetes and 15,743 control subjects. Further, pleiotropy-robust MR methods were used in sensitivity analyses using both cis and trans-pQTL.

RESULTS

We found that a genetically predicted SD increase in signal regulatory protein gamma (SIRPG) level was associated with increased risk of type 1 diabetes risk (MR odds ratio [OR] 1.66 [95% 1.36-2.03]; P = 7.1 × 10-7). The risk of type 1 diabetes increased almost twofold per genetically predicted standard deviation (SD) increase in interleukin-27 Epstein-Barr virus-induced 3 (IL27-EBI3) protein levels (MR OR 1.97 [95% CI 1.48-2.62]; P = 3.7 × 10-6). However, an SD increase in chymotrypsinogen B1 (CTRB1) was associated with decreased risk of type 1 diabetes (MR OR 0.84 [95% CI 0.77-0.90]; P = 6.1 × 10-6). Sensitivity analyses using MR methods testing for pleiotropy while including trans-pQTL showed similar results. While the MR-Egger suggested no pleotropic effect (P value MR-Egger intercept = 0.31), there was evidence of pleiotropy in MR-PRESSO (P value global test = 0.006).

CONCLUSIONS

We identified three novel circulating protein biomarkers associated with type 1 diabetes risk using an MR approach. These biomarkers are promising targets for development of drugs and/or of screening tools for early prediction of type 1 diabetes.

Blood biomarkers reflect the effects of obesity and inflammation on the human breast transcriptome

Obesity is a risk factor for the development of post-menopausal breast cancer. Breast white adipose tissue (WAT) inflammation, which is commonly found in women with excess body fat, is also associated with increased breast cancer risk. Both local and systemic effects are probably important for explaining the link between excess body fat, adipose inflammation and breast cancer. The first goal of this cross-sectional study of 196 women was to carry out transcriptome profiling to define the molecular changes that occur in the breast related to excess body fat and WAT inflammation. A second objective was to determine if commonly measured blood biomarkers of risk and prognosis reflect molecular changes in the breast. Breast WAT inflammation was assessed by immunohistochemistry. Bulk RNA-sequencing was carried out to assess gene expression in non-tumorous breast. Obesity and WAT inflammation were associated with a large number of differentially expressed genes and changes in multiple pathways linked to the development and progression of breast cancer. Altered pathways included inflammatory response, complement, KRAS signaling, tumor necrosis factor α signaling via NFkB, interleukin (IL)6-JAK-STAT3 signaling, epithelial mesenchymal transition, angiogenesis, interferon γ response and transforming growth factor (TGF)-β signaling. Increased expression of several drug targets such as aromatase, TGF-β1, IDO-1 and PD-1 were observed. Levels of various blood biomarkers including high sensitivity C-reactive protein, IL6, leptin, adiponectin, triglycerides, high-density lipoprotein cholesterol and insulin were altered and correlated with molecular changes in the breast. Collectively, this study helps to explain both the link between obesity and breast cancer and the utility of blood biomarkers for determining risk and prognosis.

Abstract 749: Plasma insulin-like growth factor 1-related biomarkers and risk of lethal prostate cancer

Background Experimental and epidemiologic evidence supports the role of plasma IGF-1 and risk of prostate cancer. About 5% of IGF-1 circulates in a free or bioavailable form, and is only weakly correlated with total IGF-1; we hypothesized that higher levels of free IGF-1 would be associated with risk of lethal prostate cancer.

Methods Lethal prostate cancer was defined as fatal prostate cancer plus metastatic prostate cancer. Non-lethal prostate cancer was defined as cases in which the men remained free of known metastases for at least eight years. Using prospectively collected samples in a nested design, we identified 434 lethal cases and 524 men with non-lethal prostate cancer in two prospective cohorts: the Physicians' Health Study (mean years of follow-up 33.2) and the Health Professionals Follow-up Study (mean years of follow-up 18.5). Circulating levels in prediagnostic plasma samples were assayed for IGF-1-related biomarkers, including free and total IGF-1, acid labile subunit (ALS), pregnancy-associated plasma protein A (PAPP-A, a protease that cleaves the IGF complex), intact IGF binding protein 4 (IGFBP-4), and total IGFBP-4, with risk of lethal prostate cancer. We estimated odds ratios (ORs) and corresponding 95% confidence intervals (CI) for the associations between IGF-1-related biomarkers (in quartiles) and lethal prostate cancer using unconditional logistic regression models adjusted for age, height, weight, and body mass index. Subgroup analyses were conducted by time from blood draw to diagnosis, and tumor biomarkers, ERG as a marker of the TMPRSS2:ERG fusion, phosphatase and tensin homolog (PTEN) loss, and IGF-1 receptor (IGF1R) protein expression.

Results We observed no significant association between free IGF-1 and lethal prostate cancer (pooled adjusted OR for the highest versus lowest group 0.93, 95% CI 0.64 to 1.35) after adjusting for potential covariates. However, men in the highest quartile of PAPP-A levels had 43% higher odds of developing lethal prostate cancer (pooled adjusted OR 1.43, 95% CI 1.05 to 1.95) compared to men in the lowest three quartiles. The positive association between PAPP-A and lethal prostate cancer was present among men without PTEN loss, but not among those with (P for interaction = 0.002). There were no significant differences across the two cohorts (P for heterogeneity &gt; 0.05 for all) and no significant associations were observed between other plasma biomarkers and lethal prostate cancer.

Conclusions We found no significant association between free IGF-1 and lethal prostate cancer, but provide suggestive evidence that higher PAPP-A levels are associated with an increased risk of developing lethal prostate cancer. This observation merits testing in other cohorts.

Citation Format: Chaoran Ma, Ye Wang, Lorelei A. Mucci, Meir J. Stampfer, Michael Pollak, Kathryn L. Penney. Plasma insulin-like growth factor 1-related biomarkers and risk of lethal prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 749.

The role of GSK3 in metabolic pathway perturbations in cancer

Malignant transformation and tumor progression are accompanied by significant perturbations in metabolic programs. As such, cancer cells support high ATP turnover to construct the building blocks needed to fuel neoplastic growth. The coordination of metabolic networks in malignant cells is dependent on the collaboration with cellular signaling pathways. Glycogen synthase kinase 3 (GSK3) lies at the convergence of several signaling axes, including the PI3K/AKT/mTOR, AMPK, and Wnt pathways, which influence cancer initiation, progression and therapeutic responses. Accordingly, GSK3 modulates metabolic processes, including protein and lipid synthesis, glucose and mitochondrial metabolism, as well as autophagy. In this review, we highlight current knowledge of the role of GSK3 in metabolic perturbations in cancer.

Effects of Adiposity and Exercise on Breast Tissue and Systemic Metabo-Inflammatory Factors in Women at High Risk or Diagnosed with Breast Cancer

Excess body fat and sedentary behavior are associated with increased breast cancer risk and mortality, including in normal weight women. To investigate underlying mechanisms, we examined whether adiposity and exercise impact the breast microenvironment (e.g., inflammation and aromatase expression) and circulating metabo-inflammatory factors. In a cross-sectional cohort study, breast white adipose tissue (WAT) and blood were collected from 100 women undergoing mastectomy for breast cancer risk reduction or treatment. Self-reported exercise behavior, body composition measured by dual-energy x-ray absorptiometry (DXA), and waist:hip ratio were obtained prior to surgery. Breast WAT inflammation (B-WATi) was assessed by IHC and aromatase expression was assessed by quantitative PCR. Metabolic and inflammatory blood biomarkers that are predictive of breast cancer risk and progression were measured. B-WATi was present in 56 of 100 patients and was associated with older age, elevated BMI, postmenopausal status, decreased exercise, hypertension and dyslipidemia (Ps < 0.001). Total body fat and trunk fat correlated with B-WATi and breast aromatase levels (Ps < 0.001). Circulating C-reactive protein, IL6, insulin, and leptin positively correlated with body fat and breast aromatase levels, while negative correlations were observed for adiponectin and sex hormone binding globulin (P < 0.001). Inverse relationships were observed with exercise (Ps < 0.05). In a subgroup of 39 women with normal BMI, body fat levels positively correlated with B-WATi and aromatase expression (Ps < 0.05). In conclusion, elevated body fat levels and decreased exercise are associated with protumorigenic micro- and host environments in normal, overweight, and obese individuals. These findings support the development of BMI-agnostic lifestyle interventions that target adiposity. PREVENTION RELEVANCE: We report that individuals with high body fat and low exercise levels have breast inflammation, higher breast aromatase expression, and levels of circulating metabo-inflammatory factors that have been associated with increased breast cancer risk. These findings support interventions to lower adiposity, even among normal weight individuals, to prevent tumor growth.

Effects of obesity on breast aromatase expression and systemic metabo-inflammation in women with BRCA1 or BRCA2 mutations

Obesity is associated with an increased risk of breast cancer in post-menopausal women and decreased risk in pre-menopausal women. Conversely, in BRCA1/2 mutation carriers, pre-menopausal obesity is associated with early-onset breast cancer. Here we show that obese, pre-menopausal BRCA1/2 mutation carriers have increased levels of aromatase and inflammation in the breast, as occurs in post-menopausal women. In a prospective cohort study of 141 women with germline BRCA1 (n = 74) or BRCA2 (n = 67) mutations, leptin, and aromatase expression were higher in the breast tissue of obese versus lean individuals (P < 0.05). Obesity was associated with breast white adipose tissue inflammation, which correlated with breast aromatase levels (P < 0.01). Circulating C-reactive protein, interleukin-6, and leptin positively correlated with body mass index and breast aromatase levels, whereas negative correlations were observed for adiponectin and sex hormone-binding globulin (P < 0.05). These findings could help explain the increased risk of early-onset breast cancer in obese BRCA1/2 mutation carriers.

Pregnancy-Associated Plasma Protein-A (PAPP-A) in Ewing Sarcoma: Role in Tumor Growth and Immune Evasion

BACKGROUND

Ewing sarcoma (EWS) manifests one of the lowest somatic mutation rates of any cancer, leading to a scarcity of druggable mutations and neoantigens. Immunotherapeutics targeting differentially expressed cell surface antigens could provide therapeutic benefit for such tumors. Pregnancy-associated plasma protein A (PAPP-A) is a cell membrane-associated proteinase produced by the placenta that promotes fetal growth by inducing insulinlike growth factor (IGF) signaling.

METHODS

By comparing RNA expression of cell surface proteins in EWS (n = 120) versus normal tissues (n = 42), we comprehensively characterized the surfaceome of EWS to identify highly differentially expressed molecules. Using CRISPR/Cas-9 and anti-PAPP-A antibodies, we investigated biological roles for PAPP-A in EWS in vitro and in vivo in NSG xenograft models and performed RNA-sequencing on PAPPA knockout clones (n = 5) and controls (n = 3). All statistical tests were two-sided.

RESULTS

EWS surfaceome analysis identified 11 highly differentially overexpressed genes, with PAPPA ranking second in differential expression. In EWS cell lines, genetic knockout of PAPPA and treatment with anti-PAPP-A antibodies revealed an essential survival role by regulating local IGF-1 bioavailability. MAb-mediated PAPPA inhibition diminished EWS growth in orthotopic xenografts (leg area mm2 at day 49 IgG2a control (CTRL) [n = 14], mean = 397.0, SD = 86.1 vs anti-PAPP-A [n = 14], mean = 311.7, SD = 155.0; P = .03; median OS anti-PAPP-A = 52.5 days, 95% CI = 46.0 to 63.0 days vs IgG2a = 45.0 days, 95% CI = 42.0 to 52.0 days; P = .02) and improved the efficacy of anti-IGF-1R treatment (leg area mm2 at day 49 anti-PAPP-A + anti-IGF-1R [n = 15], mean = 217.9, SD = 148.5 vs IgG2a-CTRL; P < .001; median OS anti-PAPP-A + anti-IGF1R = 63.0 days, 95% CI = 52.0 to 67.0 days vs IgG2a-CTRL; P < .001). Unexpectedly, PAPPA knockout in EWS cell lines induced interferon (IFN)-response genes, including proteins associated with antigen processing/presentation. Consistently, gene expression profiles in PAPPA-low EWS tumors were enriched for immune response pathways.

CONCLUSION

This work provides a comprehensive characterization of the surfaceome of EWS, credentials PAPP-A as a highly differentially expressed therapeutic target, and discovers a novel link between IGF-1 signaling and immune evasion in cancer, thus implicating shared mechanisms of immune evasion between EWS and the placenta.

Subclinical hypothyroidism and the risk of cancer incidence and cancer mortality: a systematic review

BACKGROUND

Thyroid hormone has been shown to be involved in carcinogenesis via its effects on cell proliferation pathways. The objective of this study is to determine the association between subclinical hypothyroidism (SCH) and the risk of incident cancer and cancer mortality via systematic review.

METHODS

A systematic search was performed on Medline and Pubmed to identify relevant studies. Randomized controlled trials, and observational studies assessing SCH or its treatment and the risk of incident cancer or cancer mortality were identified.

RESULTS

A total of 7 cohort and 2 case-control studies met our inclusion criteria. In general, these studies were of medium to good quality. Overall, studies revealed no association between SCH and breast and prostate cancer. One study found that untreated SCH may be associated with an increased risk of colorectal cancer (adjusted odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.08-1.24). One study showed an increased risk in thyroid cancer incidence (adjusted OR: 3.38; 95% CI: 2.05-5.59) associated with elevation of a thyroid stimulating hormone (TSH) of > 1.64mIU/L. Two studies found an increase in cancer mortality among patients with SCH compared to euthyroid individuals; in contrast one study found no association between subclinical hypothyroidism and cancer mortality among aging men.

CONCLUSION

The number of studies examining thyroid dysfunction and cancer risk and mortality is limited. Future studies assessing the association between thyroid dysfunction and cancer risk and mortality are needed, which will further address the need to treat subclinical hypothyroidism.

Prediagnostic use of low-dose aspirin and risk of incident metastasis and all-cause mortality among patients with colorectal cancer

AIMS

Previous studies suggest that the use of low-dose aspirin before a colorectal cancer (CRC) diagnosis may be associated with a decreased risk of CRC progression. Data supporting this association, however, have been inconsistent. We evaluate whether the use of prediagnostic low-dose aspirin is associated with a lower risk of metastases and all-cause mortality in CRC patients.

METHODS

Using a large Italian population-based primary care database, we identified a cohort of 7478 patients newly diagnosed with nonmetastatic CRC between 2000 and 2013. Use of prediagnostic low-dose aspirin was compared with no use of low-dose aspirin. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) of incident metastasis and of all-cause mortality associated with prediagnostic low-dose aspirin use, both overall and by duration of use.

RESULTS

There were 314 incident metastatic events and 2189 deaths during a mean follow-up time of 4.4 and 4.7 years, respectively. Overall prediagnostic use of low-dose aspirin was not associated with a decreased risk of incident metastasis (HR 0.88; 95% CI 0.63-1.22) or all-cause mortality (HR 1.09; 95% CI 0.96-1.22) in CRC patients. Cumulative duration of aspirin use was not associated with a decreased risk of incident metastasis (P-trend = .22) or all-cause mortality (P-trend = .38). These findings remained consistent in sensitivity analyses.

CONCLUSION

In this real-world, population-based study, the prediagnostic use of low-dose aspirin was not associated with a decreased risk of incident metastasis or all-cause mortality in CRC patients.

The associations of anthropometric, behavioural and sociodemographic factors with circulating concentrations of IGF-I, IGF-II, IGFBP-1, IGFBP-2 and IGFBP-3 in a pooled analysis of 16,024 men from 22 studies

Insulin-like growth factors (IGFs) and insulin-like growth factor binding proteins (IGFBPs) have been implicated in the aetiology of several cancers. To better understand whether anthropometric, behavioural and sociodemographic factors may play a role in cancer risk via IGF signalling, we examined the cross-sectional associations of these exposures with circulating concentrations of IGFs (IGF-I and IGF-II) and IGFBPs (IGFBP-1, IGFBP-2 and IGFBP-3). The Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group dataset includes individual participant data from 16,024 male controls (i.e. without prostate cancer) aged 22-89 years from 22 prospective studies. Geometric means of protein concentrations were estimated using analysis of variance, adjusted for relevant covariates. Older age was associated with higher concentrations of IGFBP-1 and IGFBP-2 and lower concentrations of IGF-I, IGF-II and IGFBP-3. Higher body mass index was associated with lower concentrations of IGFBP-1 and IGFBP-2. Taller height was associated with higher concentrations of IGF-I and IGFBP-3 and lower concentrations of IGFBP-1. Smokers had higher concentrations of IGFBP-1 and IGFBP-2 and lower concentrations of IGFBP-3 than nonsmokers. Higher alcohol consumption was associated with higher concentrations of IGF-II and lower concentrations of IGF-I and IGFBP-2. African Americans had lower concentrations of IGF-II, IGFBP-1, IGFBP-2 and IGFBP-3 and Hispanics had lower IGF-I, IGF-II and IGFBP-3 than non-Hispanic whites. These findings indicate that a range of anthropometric, behavioural and sociodemographic factors are associated with circulating concentrations of IGFs and IGFBPs in men, which will lead to a greater understanding of the mechanisms through which these factors influence cancer risk.

Randomized Phase II Trial of Exercise, Metformin, or Both on Metabolic Biomarkers in Colorectal and Breast Cancer Survivors

Background

Observational data support inverse relationships between exercise or metformin use and disease outcomes in colorectal and breast cancer survivors, although the mechanisms underlying these associations are not well understood.

Methods

In a phase II trial, stage I–III colorectal and breast cancer survivors who completed standard therapy were randomly assigned to structured exercise or metformin or both or neither for 12 weeks. The primary outcome was change in fasting insulin levels; secondary outcomes included changes in other blood-based energetic biomarkers and anthropometric measurements. Analyses used linear mixed models.

Results

In total, 139 patients were randomly assigned; 91 (65%) completed follow-up assessments. Fasting insulin levels statistically significantly decreased in all three intervention arms (−2.47 μU/mL combination arm, −0.08 μU/mL exercise only, −1.16 μU/mL metformin only, + 2.79 μU/mL control arm). Compared with the control arm, all groups experienced statistically significant weight loss between baseline and 12 weeks (−1.8% combination arm, −0.22% exercise only, −1.0% metformin only, +1.55% control). The combination arm also experienced statistically significant improvements in the homeostatic model assessment for insulin resistance (−30.6% combination arm, +61.2% control) and leptin (−42.2% combination arm, −0.8% control), compared with the control arm. The interventions did not change insulin-like growth factor–1 or insulin-like growth factor binding protein–3 measurements as compared with the control arm. Tolerance to metformin limited compliance (approximately 50% of the participants took at least 75% of the planned dosages in both treatment arms).

Conclusions

The combination of exercise and metformin statistically significantly improved insulin and associated metabolic markers, as compared to the control arm, with potential greater effect than either exercise or metformin alone though power limited formal synergy testing. Larger efforts are warranted to determine if such a combined modality intervention can improve outcomes in colorectal and breast cancer survivors.

eIF4A supports an oncogenic translation program in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is a lethal malignancy with limited treatment options. Although metabolic reprogramming is a hallmark of many cancers, including PDA, previous attempts to target metabolic changes therapeutically have been stymied by drug toxicity and tumour cell plasticity. Here, we show that PDA cells engage an eIF4F-dependent translation program that supports redox and central carbon metabolism. Inhibition of the eIF4F subunit, eIF4A, using the synthetic rocaglate CR-1-31-B (CR-31) reduced the viability of PDA organoids relative to their normal counterparts. In vivo, CR-31 suppresses tumour growth and extends survival of genetically-engineered murine models of PDA. Surprisingly, inhibition of eIF4A also induces glutamine reductive carboxylation. As a consequence, combined targeting of eIF4A and glutaminase activity more effectively inhibits PDA cell growth both in vitro and in vivo. Overall, our work demonstrates the importance of eIF4A in translational control of pancreatic tumour metabolism and as a therapeutic target against PDA.

High-Fat Diet Accelerates Carcinogenesis in a Mouse Model of Barrett's Esophagus via Interleukin 8 and Alterations to the Gut Microbiome

BACKGROUND & AIMS

Barrett's esophagus (BE) is a precursor to esophageal adenocarcinoma (EAC). Progression from BE to cancer is associated with obesity, possibly due to increased abdominal pressure and gastroesophageal reflux disease, although this pathogenic mechanism has not been proven. We investigated whether environmental or dietary factors associated with obesity contribute to the progression of BE to EAC in mice.

METHODS

Tg(ED-L2-IL1RN/IL1B)#Tcw mice (a model of BE, called L2-IL1B mice) were fed a chow (control) or high-fat diet (HFD) or were crossbred with mice that express human interleukin (IL) 8 (L2-IL1B/IL8 mice). Esophageal tissues were collected and analyzed for gene expression profiles and by quantitative polymerase chain reaction, immunohistochemistry, and flow cytometry. Organoids were established from BE tissue of mice and cultured with serum from lean or obese individuals or with neutrophils from L2-IL1B mice. Feces from mice were analyzed by 16s ribosomal RNA sequencing and compared to 16s sequencing data from patients with dysplasia or BE. L2-IL1B were mice raised in germ-free conditions.

RESULTS

L2-IL1B mice fed an HFD developed esophageal dysplasia and tumors more rapidly than mice fed the control diet; the speed of tumor development was independent of body weight. The acceleration of dysplasia by the HFD in the L2-IL1B mice was associated with a shift in the gut microbiota and an increased ratio of neutrophils to natural killer cells in esophageal tissues compared with mice fed a control diet. We observed similar differences in the microbiomes from patients with BE that progressed to EAC vs patients with BE that did not develop into cancer. Tissues from dysplasias of L2-IL1B mice fed the HFD contained increased levels of cytokines that are produced in response to CXCL1 (the functional mouse homolog of IL8, also called KC). Serum from obese patients caused organoids from L2-IL1B/IL8 mice to produce IL8. BE tissues from L2-IL1B mice fed the HFD and from L2-IL1B/IL8 mice contained increased numbers of myeloid cells and cells expressing Cxcr2 and Lgr5 messenger RNAs (epithelial progenitors) compared with mice fed control diets. BE tissues from L2-IL1B mice raised in germ-free housing had fewer progenitor cells and developed less dysplasia than in L2-IL1 mice raised under standard conditions; exposure of fecal microbiota from L2-IL1B mice fed the HFD to L2-IL1B mice fed the control diet accelerated tumor development.

CONCLUSIONS

In a mouse model of BE, we found that an HFD promoted dysplasia by altering the esophageal microenvironment and gut microbiome, thereby inducing inflammation and stem cell expansion, independent of obesity.

Relationship of circulating insulin-like growth factor-I and binding proteins 1-7 with mammographic density among women undergoing image-guided diagnostic breast biopsy

Background

Mammographic density (MD) is a strong breast cancer risk factor that reflects fibroglandular and adipose tissue composition, but its biologic underpinnings are poorly understood. Insulin-like growth factor binding proteins (IGFBPs) are markers that may be associated with MD given their hypothesized role in breast carcinogenesis. IGFBPs sequester IGF-I, limiting its bioavailability. Prior studies have found positive associations between circulating IGF-I and the IGF-I:IGFBP-3 ratio and breast cancer risk. We evaluated the associations of IGF-I, IGFBP-3, and six other IGFBPs with MD.

Methods

Serum IGF measures were quantified in 296 women, ages 40–65, undergoing diagnostic image-guided breast biopsy. Volumetric density measures (MD-V) were assessed in pre-biopsy digital mammograms using single X-ray absorptiometry. Area density measures (MD-A) were estimated by computer-assisted thresholding software. Age, body mass index (BMI), and BMI²-adjusted linear regression models were used to examine associations of serum IGF measures with MD. Effect modification by BMI was also assessed.

Results

IGF-I and IGFBP-3 were not strongly associated with MD after BMI adjustment. In multivariable analyses among premenopausal women, IGFBP-2 was positively associated with both percent MD-V (β = 1.49, p value = 0.02) and MD-A (β = 1.55, p value = 0.05). Among postmenopausal women, positive relationships between IGFBP-2 and percent MD-V (β = 2.04, p = 0.003) were observed; the positive associations between IGFBP-2 and percent MD-V were stronger among lean women (BMI < 25 kg/m²) (β = 5.32, p = 0.0002; p interaction = 0.0003).

Conclusions

In this comprehensive study of IGFBPs and MD, we observed a novel positive association between IGFBP-2 and MD, particularly among women with lower BMI. In concert with in vitro studies suggesting a dual role of IGFBP-2 on breast tissue, promoting cell proliferation as well as inhibiting tumorigenesis, our findings suggest that further studies assessing the role of IGFBP-2 in breast tissue composition, in addition to IGF-1 and IGFBP-3, are warranted.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1162-8) contains supplementary material, which is available to authorized users.

mTOR as a central regulator of lifespan and aging

The mammalian/mechanistic target of rapamycin (mTOR) is a key component of cellular metabolism that integrates nutrient sensing with cellular processes that fuel cell growth and proliferation. Although the involvement of the mTOR pathway in regulating life span and aging has been studied extensively in the last decade, the underpinning mechanisms remain elusive. In this review, we highlight the emerging insights that link mTOR to various processes related to aging, such as nutrient sensing, maintenance of proteostasis, autophagy, mitochondrial dysfunction, cellular senescence, and decline in stem cell function.

Abstract 2683: Biomarkers of glucose homeostasis and inflammation and risk of prostate cancer: A case-cohort study

Background: Type 2 diabetes (T2DM) is associated with a lower risk of prostate cancer especially low-grade and localized prostate cancer. The association with aggressive prostate cancer is inconclusive. Few studies have directly examined the associations of diabetes biomarkers with prostate cancer risk. Methods: Among a cohort of 13,994 men who were on average 70.2 years (SD=5.5) and cancer free at blood draw between 1998 and 2001, 1,206 developed non-aggressive prostate cancer and 313 developed aggressive prostate cancer (AJCC stage 3-4 or Gleason score 8-10) during follow-up through June 2013. We conducted a case-cohort study including a random sub-cohort of 1,303 men, 391 non-aggressive cases and 313 aggressive cases to examine circulating hemoglobin A1c (HbA1c), c-peptide, and C-reactive protein (CRP) in relation to prostate cancer risk.

Results: HbA1c, a biomarker of hyperglycemia, was inversely associated with non-aggressive prostate cancer after adjusting for age, race, family history of prostate cancer, prostate-specific antigen screening, smoking, alcohol intake, physical activity, and total energy intake (relative risk (RR) per unit increase: 0.89, 95% confidence interval (CI): 0.79-1.00, P=0.04). Further adjustment for body mass index (BMI) attenuated the association. In contrast, HbA1c was associated with a higher risk of aggressive prostate cancer after adjusting for the covariates including BMI (RR per unit increase: 1.11, 95% CI: 0.98-1.25, P=0.11). In an analysis combining self-reported T2DM and HbA1c, men with T2DM and poor blood glucose control (HbA1c ≥6.5%) had a lower risk of developing non-aggressive prostate cancer (RR: 0.53, 95% CI: 0.30-0.95) than men without T2DM and good blood glucose control (HbA1c &lt;6.5%). After excluding men with self-reported T2DM, HbA1c was statistically significantly positively associated with risk of aggressive prostate cancer (RR per unit increase: 1.25, 95% CI: 1.04-1.51, P=0.02) but was not associated with non-aggressive prostate cancer. C-peptide and CRP were not associated with risk of either aggressive or non-aggressive prostate cancer.Conclusions: The present study suggests that men with hyperglycemia may have a lower risk of developing non-aggressive but a higher risk of developing aggressive prostate cancer. Further studies are needed to examine the role of hyperglycemia in the etiology of aggressive prostate cancer and in prostate cancer progression.

Citation Format: Ying Wang, Peter T. Campbell, Victoria L. Stevens, Christina C. Newton, Eric J. Jacobs, Michael Pollak, Susan M. Gapstur. Biomarkers of glucose homeostasis and inflammation and risk of prostate cancer: A case-cohort study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2683.

Abstract 596: Association between an empirically-derived inflammatory lifestyle score and incident colorectal cancer

Inflammation is often suggested as major pathway by which lifestyle influences the development of colorectal cancer (CRC). In the present analysis, we empirically derived an inflammatory lifestyle score (ILS) based on associations of nine lifestyle factors with serum levels of high-sensitivity C-reactive protein (hsCRP) and subsequently examined its association with incident CRC in the Cancer Prevention Study-II Nutrition Cohort. Lifestyle factors other than smoking were chosen a priori from the American Cancer Society’s Guidelines on Nutrition and Physical Activity for Cancer Prevention to include body mass index, physical activity, sedentary time, fruit/vegetable intake, variety of fruits/vegetables consumed, red/processed meat intake, ratio of whole to refined grains consumed, alcohol consumption, and smoking status. Reduced rank regression was used to create sex-specific lifestyle scores that correlate the nine lifestyle factors with hsCRP in a testing subset of 2,707 men and women with no history of cancer at the time of blood draw. In a validation subset (n=540), the derived ILS was positively correlated with serum hsCRP levels (r=0.19, p-value&lt;0.001). Model weights from reduced rank regression in the testing subset were used to calculate the ILS among 114,974 men and women of the cohort for whom hsCRP levels were not available. The association between the ILS and incident CRC was examined using Cox proportional hazards regression to estimate hazard ratios and 95% confidence intervals adjusted for age, sex, education, non-steroidal anti-inflammatory drug use, multivitamin use, postmenopausal hormone therapy, and diabetes status. Starting at baseline in 1999, during a mean follow-up of 12.6 years, 2,082 incident CRC cases were identified (1,649 colon; 433 rectum). Participants in the third and fourth ILS quartiles had 15% (95% CI: 1%, 31%) and 34% (95% CI: 18%, 53%) higher risk of CRC, respectively, than those in the first ILS quartile. A 1-standard deviation increase in the score was associated with 10% higher risk of CRC (95% CI: 1.05, 1.15). The association between the ILS and CRC did not differ across strata of sex or age (&lt;70, ≥70 years). A Lunn-McNeil competing risk model showed no evidence of a differential association of the ILS on CRC organ subtypes (colon vs. rectal). Results support evidence that a lifestyle indicative of high inflammatory potential is associated with an increased risk of developing CRC. To examine other mechanisms by which lifestyle influences CRC risk, additional analyses will use serum levels of C-peptide and hemoglobin A1c. The biomarkers will be examined individually, together (i.e., glucose homeostasis), and in combination with hsCRP (poor metabolic function) to develop lifestyle scores.

Citation Format: Mark Guinter, Susan Gapstur, W. Dana Flanders, Ying Wang, Erika Rees-Punia, Marjorie McCullough, Kassandra I. Alcaraz, Michael Pollak, Peter Campbell. Association between an empirically-derived inflammatory lifestyle score and incident colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 596.

Abstract 594: Associations of hemoglobin A1c with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort (CPS-II NC)

Self-reported type 2 diabetes mellitus (T2DM) is convincingly associated with higher risks of liver, pancreatic, colon, rectal, female breast, and endometrial cancers, and may also be associated with higher risks of ovarian, bladder and kidney cancers. This evidence largely relies on self-reported T2DM, which does not properly classify the many individuals with pre-diabetes or with undiagnosed T2DM or adequately reflect glucose control among people with T2DM. To clarify these associations, we conducted a case-cohort analysis of hemoglobin A1c (HbA1c), an indicator of circulating glucose over the past 2-to-3 months used to diagnose and monitor T2DM. Participants were identified from the CPS-II NC. From an initial cohort of 32,328 participants who were cancer-free and provided a blood sample at baseline in 1998-2001, we selected a random sub-cohort of 3,000 participants. Further, we selected all participants diagnosed between baseline and June, 2013 with a verified, incident cancer of the colorectum (n=479), liver (n=35), pancreas (n=176), female breast (n=889), endometrium (n=155), ovary (n=93), bladder (n=344), or kidney (n=110). Weighted Cox proportional hazards regression models estimated hazards ratios (HRs) and 95% confidence intervals (CI) for associations of HbA1c with cancer risks combined and stratified by organ site. HRs were adjusted for age, gender, smoking, physical activity, alcohol, and hormone-use (women only). HbA1c levels reflective of clinically-defined T2DM (&gt;=6.5%), compared to HbA1c levels in the non-diabetes range (&lt;5.7%), were associated with statistically significantly higher risks of all 9-T2DM-associated cancers combined (HR: 1.30; 95% CI: 1.05-1.60) and colorectal cancer (HR: 1.58; 95% CI: 1.14-2.19), and associations, although not statistically significant, were in the same, hypothesized directions for risks of liver (HR: 2.30), pancreas (HR: 1.60), endometrial (HR: 1.61), ovarian (HR: 1.85), bladder (HR: 1.23), and kidney (HR: 1.23) cancers. There was no suggestion of association between HbA1c and breast cancer risk (HR: 0.95). Further analyses of colorectal cancer risk combined self-reported T2DM and measured HbA1c levels. Compared to participants who had non-diabetes levels of HbA1c (&lt;=6.5%) and did not report T2DM, participants with high HbA1c levels (&gt;=6.5%) were at higher risk of CRC whether they self-reported T2DM (HR: 1.54), or not (HR:1.56), whereas participants who self-reported T2DM but had good glycemic control (HbA1c =&lt;6.5%) were not at higher risk (HR: 0.96). Results for c-peptide and CRP are forthcoming. This study suggests that HbA1c, a clinically meaningful marker of circulating glucose, is related to the etiology of some cancers.

Citation Format: Peter T. Campbell, Christina Newton, Eric J. Jacobs, Michael Pollak, Susan M. Gapstur. Associations of hemoglobin A1c with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort (CPS-II NC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 594.

Oncogenic kinases and perturbations in protein synthesis machinery and energetics in neoplasia

Notwithstanding that metabolic perturbations and dysregulated protein synthesis are salient features of cancer, the mechanism underlying coordination of cellular energy balance with mRNA translation (which is the most energy consuming process in the cell) is poorly understood. In this review, we focus on recently emerging insights in the molecular underpinnings of the cross-talk between oncogenic kinases, translational apparatus and cellular energy metabolism. In particular, we focus on the central signaling nodes that regulate these processes (e.g. the mechanistic/mammalian target of rapamycin MTOR) and the potential implications of these findings on improving the anti-neoplastic efficacy of oncogenic kinase inhibitors.

Impact of Addition of Metformin to Abiraterone in Metastatic Castration-Resistant Prostate Cancer Patients With Disease Progressing While Receiving Abiraterone Treatment (MetAb-Pro): Phase 2 Pilot Study

BACKGROUND

There is evidence linking metformin to improved prostate cancer-related outcomes.

PATIENTS AND METHODS

Twenty-five men with metastatic castration-resistant prostate cancer and prostate-specific antigen (PSA) progression while receiving treatment with abiraterone from 3 Swiss centers were included in this single-arm phase 2 trial between November 2013 and September 2016. Metformin was added to abiraterone continuously at 1000 mg twice daily in uninterrupted 4-week cycles. The primary end point was the absence of disease progression at 12 weeks (PFS12). The Fleming single-stage design was applied. With a 5% significance level and 80% power, 25 patients were required to test PFS12 ≤ 15% (H0) compared to ≥ 35% (H1). Secondary end points included toxicity and safety issues. The study was registered at ClinicalTrials.gov (NCT01677897).

RESULTS

The primary end point PFS12 was 12% (3 of 25 patients) (95% confidence interval, 3-31). Most patients had PSA progression, almost half had radiographic progression, but only 1 patient had symptomatic progression. Eleven (44%) of 25 patients had grade 1 and 2 patients each grade 2 (8%) or grade 3 (8%) gastrointestinal toxicity (nausea, diarrhea, loss of appetite). One patient discontinued treatment at week 5 because of intolerable grade 3 diarrhea.

CONCLUSION

The addition of metformin to abiraterone for patients with metastatic castration-resistant prostate cancer and PSA progression while receiving abiraterone therapy does not affect further progression and has no meaningful clinical benefit. A higher-than-expected gastrointestinal toxicity attributed to metformin was observed.

Expression of IGF/insulin receptor in prostate cancer tissue and progression to lethal disease

Circulating insulin-like growth factor-1 (IGF-1) is consistently associated with prostate cancer risk. IGF-1 binds to IGF-1 receptor (IGF1R) and insulin receptor (IR), activating cancer hallmark pathways. Experimental evidence suggests that TMPRSS2:ERG may interact with IGF/insulin signaling to influence progression. We investigated IGF1R and IR expression and its association with lethal prostate cancer among 769 men. Protein expression of IGF1R, IR and ERG (i.e. a surrogate of ERG fusion genes) were assayed by immunohistochemistry. Cox models estimated hazard ratios (HR) and 95% confidence intervals (CI) adjusted for clinical characteristics. Among patients, 29% had strong tumor IGF1R expression and 10% had strong IR expression. During a mean follow-up of 13.2 years through 2012, 80 men (11%) developed lethal disease. Tumors with strong IGF1R or IR expression showed increased cell proliferation, decreased apoptosis and a higher prevalence of ERG. In multivariable models, strong IGF1R was associated with a borderline increased risk of lethal prostate cancer (HR 1.7; 95% CI 0.9-3.1). The association appeared greater in ERG-positive tumors (HR 2.8; 95% CI 0.9-8.4) than in ERG-negative tumors (HR 1.3; 95% CI 0.6-3.0, p-heterogeneity 0.08). There was no association between IR and lethal prostate cancer (HR 0.8; 95% CI 0.4-1.9). These results suggest that tumor IGF1R expression may play a role in prostate cancer progression to a lethal phenotype and that ERG-positive tumors may be more sensitive to IGF signaling. These data may improve our understanding of IGF signaling in prostate cancer and suggest therapeutic options for disease subtypes.

Translational and HIF-1α-Dependent Metabolic Reprogramming Underpin Metabolic Plasticity and Responses to Kinase Inhibitors and Biguanides

There is increasing interest in therapeutically exploiting metabolic differences between normal and cancer cells. We show that kinase inhibitors (KIs) and biguanides synergistically and selectively target a variety of cancer cells. Synthesis of non-essential amino acids (NEAAs) aspartate, asparagine, and serine, as well as glutamine metabolism, are major determinants of the efficacy of KI/biguanide combinations. The mTORC1/4E-BP axis regulates aspartate, asparagine, and serine synthesis by modulating mRNA translation, while ablation of 4E-BP1/2 substantially decreases sensitivity of breast cancer and melanoma cells to KI/biguanide combinations. Efficacy of the KI/biguanide combinations is also determined by HIF-1α-dependent perturbations in glutamine metabolism, which were observed in VHL-deficient renal cancer cells. This suggests that cancer cells display metabolic plasticity by engaging non-redundant adaptive mechanisms, which allows them to survive therapeutic insults that target cancer metabolism.

Integrated Pharmacodynamic Analysis Identifies Two Metabolic Adaption Pathways to Metformin in Breast Cancer

Late-phase clinical trials investigating metformin as a cancer therapy are underway. However, there remains controversy as to the mode of action of metformin in tumors at clinical doses. We conducted a clinical study integrating measurement of markers of systemic metabolism, dynamic FDG-PET-CT, transcriptomics, and metabolomics at paired time points to profile the bioactivity of metformin in primary breast cancer. We show metformin reduces the levels of mitochondrial metabolites, activates multiple mitochondrial metabolic pathways, and increases 18-FDG flux in tumors. Two tumor groups are identified with distinct metabolic responses, an OXPHOS transcriptional response (OTR) group for which there is an increase in OXPHOS gene transcription and an FDG response group with increased 18-FDG uptake. Increase in proliferation, as measured by a validated proliferation signature, suggested that patients in the OTR group were resistant to metformin treatment. We conclude that mitochondrial response to metformin in primary breast cancer may define anti-tumor effect.

Serum insulin-like growth factor (IGF)-I and IGF binding protein-3 in relation to terminal duct lobular unit involution of the normal breast in Caucasian and African American women: The Susan G. Komen Tissue Bank

Lesser degrees of terminal duct lobular unit (TDLU) involution, as reflected by higher numbers of TDLUs and acini/TDLU, are associated with elevated breast cancer risk. In rodent models, the insulin-like growth factor (IGF) system regulates involution of the mammary gland. We examined associations of circulating IGF measures with TDLU involution in normal breast tissues among women without precancerous lesions. Among 715 Caucasian and 283 African American (AA) women who donated normal breast tissue samples to the Komen Tissue Bank between 2009 and 2012 (75% premenopausal), serum concentrations of IGF-I and binding protein (IGFBP)-3 were quantified using enzyme-linked immunosorbent assay. Hematoxilyn and eosin-stained tissue sections were assessed for numbers of TDLUs ("TDLU count"). Zero-inflated Poisson regression models with a robust variance estimator were used to estimate relative risks (RRs) for association of IGF measures (tertiles) with TDLU count by race and menopausal status, adjusting for potential confounders. AA (vs. Caucasian) women had higher age-adjusted mean levels of serum IGF-I (137 vs. 131 ng/mL, p = 0.07) and lower levels of IGFBP-3 (4165 vs. 4684 ng/mL, p < 0.0001). Postmenopausal IGFBP-3 was inversely associated with TDLU count among AA (RR_T3vs.T1  = 0.49, 95% CI = 0.28-0.84, p-trend = 0.04) and Caucasian (RR_T3vs.T1 =0.64, 95% CI = 0.42-0.98, p-trend = 0.04) women. In premenopausal women, higher IGF-I:IGFBP-3 ratios were associated with higher TDLU count in Caucasian (RR_T3vs.T1 =1.33, 95% CI = 1.02-1.75, p-trend = 0.04), but not in AA (RR_T3vs.T1 =0.65, 95% CI = 0.42-1.00, p-trend = 0.05), women. Our data suggest a role of the IGF system, particularly IGFBP-3, in TDLU involution of the normal breast, a breast cancer risk factor, among Caucasian and AA women.

Abstract A36: Serum insulin-like growth factor (IGF)-I and IGF binding protein-3 in relation to terminal duct lobular unit involution in Caucasian and African American women: The Susan G. Komen Tissue Bank

Background: Insulin-like growth factor (IGF)-I and IGF binding protein (IGFBP)-3 play important roles in carcinogenesis, particularly for breast cancer. However, little is known about whether the IGF system influences histologic characteristics of normal glandular tissue and whether relationships vary by race. Lesser degrees of age-related terminal duct lobular unit (TDLU) involution, as reflected by higher numbers of TDLUs and acini per TDLU, have been associated with higher breast cancer risk. We examined the associations of IGF measures with TDLU involution of normal breast using standardized TDLU measures.

Methods: Among 715 Caucasian and 283 African American (AA) women with normal breast tissue samples from the Komen Tissue Bank, serum concentrations of IGF-I and IGFBP-3 were quantified using enzyme-linked immunosorbent assay (ELISA). Hematoxilyn and eosin-stained tissue sections were assessed for numbers of TDLUs (“TDLU count”) and acini/TDLU. Zero-inflated Poisson regression models with a robust variance estimator were used to estimate associations of IGF-I, IGFBP-3, and IGF-I:IGFBP-3 molar ratio (tertiles) with TDLU count by race and menopausal status, adjusting for potential confounders. We also tested for interactions by race using likelihood ratio tests.

Results: AA (vs. Caucasian) women had higher age-adjusted mean levels of serum IGF-I (137 vs. 131 ng/mL, p=0.07) and lower levels of IGFBP-3 (4165 vs. 4684 ng/mL, p&lt;0.0001); the differences persisted after adjustment for additional covariates including BMI and parity/age at first birth. Postmenopausal IGFBP-3 was inversely associated with TDLU count among both AA (RR T3vs.T1=0.49, 95% CI=0.28-0.84, p-trend=0.04) and Caucasian (RR T3vs.T1=0.63, 95% CI=0.41-0.99, p-trend=0.04) women. In premenopausal women, higher IGF-I:IGFBP-3 ratios were associated with higher TDLU count in Caucasians (OR T3vs.T1=1.33, 95% CI=1.01-1.31, p-trend=0.04) but not in AA (OR T3vs.T1=0.65, 95% CI=0.42-1.00, p-trend=0.05) women. There was no statistically significant interaction by race (p-interaction≥0.10).

Conclusions: Our data suggest the potential role of the IGF system, particularly IGFBP-3, in TDLU involution of the normal breast among both Caucasian and AA women.

Citation Format: Hannah OH, Ruth M. Pfeiffer, Roni T. Falk, Hisani N. Horne, Jackie Xiang, Michael Pollak, Louise A. Brinton, Anna Maria V. Storniolo, Mark E. Sherman, Gretchen L. Gierach, Jonine D. Figueroa. Serum insulin-like growth factor (IGF)-I and IGF binding protein-3 in relation to terminal duct lobular unit involution in Caucasian and African American women: The Susan G. Komen Tissue Bank [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr A36.

Abstract 3269: Metformin to prevent metabolic syndrome associated with androgen deprivation therapy (ADT): Metabolic analysis from a placebo-controlled study of metformin in non-diabetic men initiating ADT for advanced prostate cancer (PCa)

Background: ADT results in metabolic syndrome, characterized by hyperinsulinemia, insulin resistance and obesity. The hyperinsulinemia may result in ADT resistance; therefore preventing metabolic syndrome could have a therapeutic impact on PCa. Metformin decreases glucose & insulin by inhibiting hepatic gluconeogenesis. There is preclinical evidence for additional antineoplastic activity due to mTOR inhibition secondary to AMPK activation. Methods: We analyzed serum and PBMC from a recently completed clinical study of men with advanced PCa on ADT that were randomized 1:1 to metformin at 500mg TID or color matched placebo. Subjects serum insulin/glucose, metformin levels, weight and waist circumference (WC) was assessed at baseline, week 12 and 28. The primary endpoint of study was the metabolic consequences of metformin vs placebo cohort. Secondary endpoints were PSA response and PBMC analysis of downstream target of mTOR, phospho-S6 kinase. Results: There were 36 evaluable men. The mean age on study was 68.4. Mean weight, WC and insulin at baseline in metformin cohort was 187 lbs, 41.14 cm and 10.03 mIU/L respectively, and 177.65 lbs, 40.52 cm and 8.02 mIU/L in placebo cohort. An increase in mean weight, WC and insulin levels was seen in both cohorts. At week 12 and 28, no statistical difference in weight, WC and insulin was observe in either cohort. Four men randomized to metformin had undetectable serum drug levels despite drug-diary suggesting compliance; excluding them did not result in significant metabolic change. Assessing efficacy, 50% in metformin and 53.3% in placebo cohort achieved undetectable PSA at week 28; difference not statistically significant. PBMC analysis demonstrated variable down-regulation of phospho-S6 kinase in the metformin cohort. Conclusion: This study detected no impact of MET addition to ADT on the risk of metabolic syndrome and no additional anti-tumor effects. Control of hyperinsulinemia related to diabetes by MET does not necessarily imply MET has a similar action on hyperinsulinemia due to ADT.

Citation Format: Devalingam Mahalingam, Salih Hanni, Christos Fountzilas, Joel Michalek, John Sarantopoulos, Sureshkumar Mulampurath Achuthan Pillai, John Kuhn, Michael Pollak, Ian Thompson. Metformin to prevent metabolic syndrome associated with androgen deprivation therapy (ADT): Metabolic analysis from a placebo-controlled study of metformin in non-diabetic men initiating ADT for advanced prostate cancer (PCa) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3269.

Insulin-like growth factor 1 receptor stabilizes the ETV6-NTRK3 chimeric oncoprotein by blocking its KPC1/Rnf123-mediated proteasomal degradation

Many oncogenes, including chimeric oncoproteins, require insulin-like growth factor 1 receptor (IGF1R) for promoting cell transformation. The ETS variant 6 (ETV6)-neurotrophic receptor tyrosine kinase 3 (NTRK3) (EN) chimeric tyrosine kinase is expressed in mesenchymal, epithelial, and hematopoietic cancers and requires the IGF1R axis for transformation. However, current models of IGF1R-mediated EN activation are lacking mechanistic detail. We demonstrate here that IGF-mediated IGF1R stimulation enhances EN tyrosine phosphorylation and that blocking IGF1R activity or decreasing protein levels of the adaptor protein insulin receptor substrate 1/2 (IRS1/2) results in rapid EN degradation. This was observed both in vitro and in vivo in fibroblast and breast epithelial cell line models and in MO91, an EN-expressing human leukemia cell line. Stable isotope labeling with amino acids in cell culture (SILAC)-based MS analysis identified the E3 ligase RING-finger protein 123 (Rnf123, more commonly known as KPC1) as an EN interactor upon IGF1R/insulin receptor (INSR) inhibitor treatment. KPC1/Rnf123 ubiquitylated EN in vitro, and its overexpression decreased EN protein levels. In contrast, KPC1/Rnf123 knockdown rendered EN resistant to IGF1R inhibitor-mediated degradation. These results support a critical function for IGF1R in protecting EN from KPC1/Rnf123-mediated proteasomal degradation. Attempts to therapeutically target oncogenic chimeric tyrosine kinases have traditionally focused on blocking kinase activity to restrict downstream activation of essential signaling pathways. In this study, we demonstrate that IGF1R inhibition results in rapid ubiquitylation and degradation of the EN oncoprotein through a proteasome-dependent mechanism that is reversible, highlighting a potential strategy for targeting chimeric tyrosine kinases in cancer.

Metformin regulates metabolic and nonmetabolic pathways in skeletal muscle and subcutaneous adipose tissues of older adults

Administration of metformin increases healthspan and lifespan in model systems, and evidence from clinical trials and observational studies suggests that metformin delays a variety of age‐related morbidities. Although metformin has been shown to modulate multiple biological pathways at the cellular level, these pleiotropic effects of metformin on the biology of human aging have not been studied. We studied ~70‐year‐old participants (n = 14) in a randomized, double‐blind, placebo‐controlled, crossover trial in which they were treated with 6 weeks each of metformin and placebo. Following each treatment period, skeletal muscle and subcutaneous adipose tissue biopsies were obtained, and a mixed‐meal challenge test was performed. As expected, metformin therapy lowered 2‐hour glucose, insulin AUC, and insulin secretion compared to placebo. Using FDR<0.05, 647 genes were differentially expressed in muscle and 146 genes were differentially expressed in adipose tissue. Both metabolic and nonmetabolic pathways were significantly influenced, including pyruvate metabolism and DNA repair in muscle and PPAR and SREBP signaling, mitochondrial fatty acid oxidation, and collagen trimerization in adipose. While each tissue had a signature reflecting its own function, we identified a cascade of predictive upstream transcriptional regulators, including mTORC1, MYC, TNF, TGFß1, and miRNA‐29b that may explain tissue‐specific transcriptomic changes in response to metformin treatment. This study provides the first evidence that, in older adults, metformin has metabolic and nonmetabolic effects linked to aging. These data can inform the development of biomarkers for the effects of metformin, and potentially other drugs, on key aging pathways.

On dynamical properties of electrons in Anderson-Mott insulators

Properties of electrons in non-crystalline (alias disordered) systems has been a very active research topic for over half a century, since Anderson's ground breaking paper on localization. In strongly disordered systems electrons become Anderson and Mott localized. Interactions become important because screening by localized electrons is ineffective. Dynamical theories for such systems have long been controversial. Nevertheless one theory came to prominence in the literature and is often invoked and/or used. It is shown here that that theory is unsatisfactory in several aspects. It is based on the one-particle density of states, which turns out to be irrelevant to the problem it addresses. Another shortcoming is an implicit conjecture that interacting electrons move independently of each other. The theory is also in questionable agreement with experiment. It is shown that two other theories are free of those problems. They are useful for different types of studies, are compatible with each other and in agreement with experiment.

The Association Between IGF-I and IGFBP-3 and Incident Diabetes in an Older Population of Men and Women in the Cardiovascular Health Study

CONTEXT

Insulin-like growth factor-I (IGF-I) has structural and functional similarities to insulin and may play a role in glucose homeostasis, along with insulin-like growth factor binding protein-3 (IGFBP-3), which binds the majority of circulating IGF-I.

OBJECTIVE

To assess whether IGF-I and IGFBP-3 are associated with a higher risk of incident diabetes in older adults.

DESIGN

Participants in the Cardiovascular Health Study (n = 3133), a cohort of adults aged ≥65 years, were observed for 16 years (n = 3133) for the development of incident diabetes. Statistical models were fit separately for men and women because of interactions with sex (P interaction: IGF-I, 0.02; IGFBP-3, 0.009) and were adjusted for relevant covariates.

SETTING

General community.

PARTICIPANTS

Older adults who were nondiabetic at baseline and who did not develop diabetes within the first year of follow-up.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Incident diabetes as measured by fasting plasma glucose (FPG) ≥126 mg/dL, non-FPG ≥200 mg/dL, use of pharmacological treatment of diabetes, or existence of two or more inpatient or three or more outpatient or (at least one inpatient and at least one outpatient) Centers for Medicare & Medicaid Services claims with the diagnostic International Classification of Diseases, Ninth Revision, Clinical Modification code of 250.xx.

RESULTS

In women, higher IGFBP-3 (hazard ratio tertile 3 vs tertile 1 = 2.30; 95% confidence interval, 1.55 to 3.40; P trend < 0.0001) was significantly associated with incident diabetes. Total IGF-I was not significantly associated with incident diabetes. In men, neither IGF-I nor IGFBP-3 was significantly associated with incident diabetes.

CONCLUSIONS

We confirmed a previously reported association between circulating IGFBP-3 and diabetes risk in the older adult population, establishing that this association is present among women but could not be shown to be associated in men.

Long-Term Use of Long-Acting Insulin Analogs and Breast Cancer Incidence in Women With Type 2 Diabetes

Purpose

The association between long-acting insulin analogs and increased breast cancer risk is uncertain, particularly with the short follow-up in previous studies. We assessed this risk long term in women with type 2 diabetes.

Methods

A population-based cohort of women 40 years or older, all of whom were treated with long-acting (glargine, detemir) or neutral protamine Hagedorn (NPH) insulin between 2002 and 2012, was formed using the United Kingdom’s Clinical Practice Research Datalink. Women were followed until February 2015 or breast cancer diagnosis. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs) and 95% CIs of incident breast cancer, comparing long-acting insulin analogs with NPH overall, as well as by duration and cumulative dose.

Results

The cohort included 22,395 women who received insulin treatment, with 321 incident breast cancer events occurring during up to 12 years of follow-up (incidence rate 3.3 per 1,000 person-years). Compared with NPH insulin, insulin glargine was associated with an increased risk of breast cancer (HR, 1.44; 95% CI, 1.11 to 1.85), mainly increasing 5 years after glargine initiation (HR, 2.23; 95% CI, 1.32 to 3.77) and after > 30 prescriptions (HR, 2.29; 95% CI, 1.26 to 4.16). The risk was particularly elevated among prior insulin users (HR, 1.53; 95% CI, 1.10 to 2.12) but not for new users, which included fewer patients and for which one cannot rule out an HR of 1.81. The risk associated with insulin detemir was not significantly elevated (HR, 1.17; 95% CI, 0.77 to 1.77).

Conclusion

Long-term use of insulin glargine is associated with an increased risk of breast cancer in women with type 2 diabetes. The risk associated with insulin detemir remains uncertain because there are fewer users of this insulin.

The effects of metformin on gut microbiota and the immune system as research frontiers

Recent studies have revealed that metformin influences gut microbiota and the immune system although neither is a classic target of the drug. This research has revealed complexity not previously appreciated, and opened new research directions. The extent to which immunomodulatory effects and actions on the microbiota are related to each other and account for effects on host energy metabolism remains to be determined. These sites of action may be relevant not only to the efficacy of metformin for its established use in type 2 diabetes, but also to proposed novel indications in oncology and other diseases.

Prediagnosis Circulating Insulin-Like Growth Factors and Pancreatic Cancer Survival

BACKGROUND

Prediagnosis obesity and diabetes are associated with survival from pancreatic cancer, but the underlying mechanisms have not been characterized. Because both are associated with dysregulation in circulating insulin-like growth factor (IGF) levels, we evaluated the associations of prediagnosis IGF levels (IGF-I, IGF-II) and IGF binding protein 3 (IGFBP-3) with pancreatic cancer survival.

METHODS

Participants were subjects enrolled in the intervention arm of the PLCO Cancer Screening Trial who developed exocrine pancreatic cancer during follow-up (N = 178, 116 men and 67 women). Participants provided blood samples at enrollment, before cancer diagnosis. Cox proportional hazards regression model, adjusted for confounders was used to investigate associations of IGF biomarkers with pancreatic cancer survival. Because of the well-documented, gender-specific differences in circulating IGF biomarkers, and differential associations of IGF biomarkers with mortality, we evaluated associations separately among males and females.

RESULTS

Median survival was 172 days. Higher IGF-II and IGFBP-3 levels were associated with pancreatic cancer survival among males but not among females. The hazard ratios (HR) of death among men in the highest tertiles of IGF-II and IGFBP-3 compared with men in the lowest tertiles were 0.40 (95% confidence interval (CI) 0.23-0.71, p < 0.01) and 0.59 (95% CI 0.35-0.97, p = 0.10), respectively. There were no statistically significant associations between IGF-I concentrations, IGF-I/IGFBP-3, and pancreatic cancer survival.

CONCLUSIONS

Higher prediagnosis circulating IGF-II and IGFBP-3 levels are associated with better pancreatic cancer survival among men but not women. A greater understanding of how IGF signaling is related to pancreatic cancer survival could have utility in improving pancreatic cancer prognosis.

Abstract 4420: Elevated glycolytic gene signature in patient-derived neuroendocrine prostate cancer xenograft models and its clinical relevance

Neuroendocrine prostate cancer (NEPC) is a highly aggressive subtype of prostate cancer (PCa) that is becoming increasingly common in the clinic. While the vast majority of PCa presents as androgen-dependent adenocarcinoma, recent uses of increasingly potent therapeutics targeting the androgen receptor signaling axis has resulted in the promotion of NEPC transdifferentiation as a mechanism of treatment resistance. Unfortunately, there is currently no effective treatment option for NEPC. Altered cancer metabolism is now recognized as a hallmark of cancer and a crucial factor for promoting tumour growth and spread. In particular, altered glucose metabolism and the resultant acidification of the tumor microenvironment via increased lactic acid production has been shown to play an important role in multiple cancer-promoting processes, including tissue invasion/metastasis, angiogenesis, and suppression of local anticancer immunity. While increased glycolysis is not generally considered a phenomenon relevant to primary treatment-naive PCa, we have recently demonstrated its relavance to castration-resistant prostate cancer (CRPC) and thus suspect that it is also relevant to the more aggressive NEPC. Our laboratory has also developed a number of unique serially transplantable patient-derived xenograft (PDX) models of NEPC that are histologically highly similar to the donor tissues and retain important genetic and epigenetic features. In particular, we have developed the first spontaneous NEPC transdifferentiation model in the field (LTL331/331R). The gene expression profiles of these NEPC PDX models were compared to that of PCa adenocarcinoma PDX models. To determine whether certain metabolic pathway alterations were specific to NEPC, genes from a number of key metabolic pathways were compiled and overall pathway scores were generated using average expression z-scores. Furthermore, publically available gene expression data from NEPC patient tumors were used to validate our findings. From our analysis, we found that genes in the glycolysis pathway were signficiantlly upregulatied in both our PDX models and also in patient NEPC samples. Of particular interest is the upregulation of genes involved in the production and secretion of lactic acid, such as LDHA and MCT4. As such, our results suggest that elevated glycolysis and production of lactic acid could be a clinically important NEPC phenotype. Furthermore, the inhibition of glycolysis and particularly the inhibition of lactic acid secretion via MCT4 could be a potentially viable therapeutic strategy for NEPC.

Citation Format: Stephen Y. Choi, Susan L. Ettinger, Dong Lin, Hui Xue, Robert H. Bell, Fan Mo, Michael Pollak, Colin C. Collins, Yuzhuo Wang. Elevated glycolytic gene signature in patient-derived neuroendocrine prostate cancer xenograft models and its clinical relevance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4420. doi:10.1158/1538-7445.AM2017-4420

Menopause Is a Determinant of Breast Aromatase Expression and Its Associations With BMI, Inflammation, and Systemic Markers

CONTEXT

Most estrogen-dependent breast cancers occur after menopause, despite low levels of circulating estrogens. Breast expression of the estrogen-biosynthetic enzyme, aromatase, is proposed to drive breast cancer development after menopause. However, the effects of menopause on breast aromatase expression are unknown.

OBJECTIVE

To determine the effect of menopause on breast aromatase expression in relation to body mass index (BMI), white adipose tissue inflammation (WATi), and systemic markers of metabolic dysfunction.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of 102 premenopausal (age 27 to 56) and 59 postmenopausal (age 45 to 74) women who underwent mastectomy for breast cancer treatment/prevention.

OUTCOME

Breast tissue was assessed for the presence of crown-like structures and the expression and activity of aromatase. Systemic markers examined include interleukin (IL)-6, insulin, glucose, leptin, adiponectin, high-sensitivity C-reactive protein (hsCRP), cholesterol, and triglycerides. Multivariable analysis was performed for aromatase messenger RNA (mRNA) in relation to BMI, WATi, and blood markers.

RESULTS

Postmenopausal women had higher BMI and more breast WATi than premenopausal women. Fasting levels of IL-6, glucose, leptin, hsCRP, and homeostatic model assessment 2 insulin resistance score were higher in the postmenopausal group. BMI was positively correlated with aromatase mRNA in both pre- and postmenopausal women. Aromatase levels were higher in breast tissue of postmenopausal women, with levels being higher in inflamed vs noninflamed, independent of BMI. Adipocyte diameter and levels of leptin, hsCRP, adiponectin, and high-density lipoprotein cholesterol were more strongly correlated with aromatase in postmenopausal than premenopausal women.

CONCLUSIONS

Elevated aromatase in the setting of adipose dysfunction provides a possible mechanism for the higher incidence of hormone-dependent breast cancer in obese women after menopause.

Metabolic heterogeneity signature of primary treatment-naïve prostate cancer

To avoid over- or under-treatment of primary prostate tumours, there is a critical need for molecular signatures to discriminate indolent from aggressive, lethal disease. Reprogrammed energy metabolism is an important hallmark of cancer, and abnormal metabolic characteristics of cancers have been implicated as potential diagnostic/prognostic signatures. While genomic and transcriptomic heterogeneity of prostate cancer is well documented and associated with tumour progression, less is known about metabolic heterogeneity of the disease. Using a panel of high fidelity patient-derived xenograft (PDX) models derived from hormone-naïve prostate cancer, we demonstrated heterogeneity of expression of genes involved in cellular energetics and macromolecular biosynthesis. Such heterogeneity was also observed in clinical, treatment-naïve prostate cancers by analyzing the transcriptome sequencing data. Importantly, a metabolic gene signature of increased one-carbon metabolism or decreased proline degradation was identified to be associated with significantly decreased biochemical disease-free patient survival. These results suggest that metabolic heterogeneity of hormone-naïve prostate cancer is of biological and clinical importance and motivate further studies to determine the heterogeneity in metabolic flux in the disease that may lead to identification of new signatures for tumour/patient stratification and the development of new strategies and targets for therapy of prostate cancer.

Abstract A31: eIF4F links translation to energy stress response in cancer

Protein synthesis is one of the most energy consuming process in the cell. Oncogenic kinases (e.g. EGFR/HER2, BCR/ABL and BRAF) play a central role in reprogramming translation and energy metabolism in neoplasia, whereby cancer cells must provide sufficient ATP to support increased levels of protein synthesis required for neoplastic growth. The downstream mechanisms that link translational machinery and energy homeostasis in cancer, however, remain largely unknown.

We found that widely used anti-diabetics (biguanides) abrogate adaptations to EGFR/HER2 inhibitor-induced energetic stress, which results in synergistic anti-neoplastic effects both in vitro and in vivo. In turn, breast cancer cells in which 4E-BP1/2 expression was abrogated by CRISPR were partially resistant to the combination of EGFR/HER2 inhibitors and biguanides. This was paralleled by the inability of the drugs to inhibit the eIF4F complex assembly and translation of mRNAs encoding important metabolic regulators including those involved in serine biogenesis (PHGDH, PSAT1) and one carbon metabolism (MTHFD1L).

Comparable results were observed when BRAF and BCR/ABL inhibitors were combined with biguanides, which suggests that translational regulation of metabolic genes via the mTORC1/4E-BE/eIF4E pathway plays a major role in energy stress response in cancer.

Together our findings demonstrate that the eIF4F complex is an important mediator of metabolic adaptation in response to the combination of biguanides and clinically-used kinase inhibitors and suggest that the efficiency of such anti-cancer strategies are dependent on the integrity of the translation initiation machinery.

Citation Format: Laura Hulea, Marie Cargnello, Simon-Pierre Gravel, Young Im, Shannon McLaughlan, Yunhua Zhao, Jenna Ching, Yutian Cai, Ola Larsson, Michael Ohh, Josie Ursini-Siegel, Julie St-Pierre, Michael Pollak, Ivan Topisirovic. eIF4F links translation to energy stress response in cancer. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr A31.