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

Serum C-peptide, Total and High Molecular Weight Adiponectin, and Pancreatic Cancer: Do Associations Differ by Smoking?

Background: Studies examining associations between circulating concentrations of C-peptide and total adiponectin, two biomarkers related to obesity and insulin secretion and sensitivity and pancreatic ductal adenocarcinoma (PDA) risk have shown inconsistent results and included limited numbers of smokers.Methods: We examined associations of these biomarkers and high molecular weight (HMW) adiponectin with PDA, overall, and by smoking status. We conducted a pooled nested case-control analysis in 3 cohorts (Prostate, Lung, Colorectal, and Ovarian Cancer Trial, Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, and Cancer Prevention Study-II), with 758 cases (435 current smokers) and 1,052 controls (531 smokers) matched by cohort, age, sex, race, blood draw date and follow-up time. We used conditional logistic regression adjusted for age, smoking, diabetes, and body mass index to calculate ORs and 95% confidence intervals (CI).Results: Circulating C-peptide concentration was not associated with PDA in never or former smokers, but was inversely associated with PDA in current smokers (per SD OR = 0.67; 95% CI, 0.54-0.84; Pinteraction = 0.005). HMW adiponectin was inversely associated with PDA in never smokers (OR = 0.43; 95% CI, 0.23-0.81), not associated in former smokers, and positively associated in smokers (OR = 1.23; 95% CI, 1.04-1.45; Pinteraction = 0.009). Total adiponectin was not associated with PDA in nonsmokers or current smokers.Conclusions: Associations of biomarkers of insulin secretion and sensitivity with PDA differ by smoking status. Smoking-induced pancreatic damage may explain the associations in smokers while mechanisms related to insulin resistance associations in nonsmokers.Impact: Future studies of these biomarkers and PDA should examine results by smoking status. Cancer Epidemiol Biomarkers Prev; 26(6); 914-22. ©2017 AACR.

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.