Abstract PD03-05: Analysis of tumour cell signaling in response to neoadjuvant metformin in women with early stage breast cancer

Background: The anti-diabetic drug metformin, commonly used to treat type 2 diabetes due to its ability to reduce circulating glucose and insulin, has emerged as a potential anti-cancer agent. Observational studies have reported decreased cancer incidence and mortality in diabetics receiving metformin. Metformin's ability to reduce insulin may be particularly important for breast cancer (BC) because hyperinsulinemia is an adverse prognostic factor and most cells express the insulin receptor (IR). The anti-cancer effects of metformin are associated with both direct (insulin-independent) and indirect (insulin-dependent) actions. Direct effects are linked to activation of AMPK and an inhibition of mTOR signalling, while indirect effects are mediated by reductions in circulating insulin levels, leading to reduced IR-activated PI3K signalling. We conducted a neoadjuvant, single arm, “window of opportunity” trial examining the clinical and biological effects of metformin on thirty-nine locoregional BC patients awaiting definitive surgery.

Methods: Non-diabetic women with newly diagnosed, untreated BC were given metformin 500 mg tid for ≥2 weeks post diagnostic core biopsy until surgery. Fasting blood and tumour samples were collected at diagnosis and surgery. Blood glucose and insulin were assayed to assess the physiologic effects of metformin, while IHC analysis of tumours was used to characterize cellular markers before and after metformin. Specifically, IR levels and the phosphorylation status of proteins involved in AMPK and PI3K/AKT/mTOR signalling, including AMPK (T172) and AKT (S473), were examined.

Results: 39 patients with a mean age of 51 years received metformin for a median of 18 days (range 13–40) with minor GI toxicities. The clinical effects (previously reported) included significant (p < 0.05) decreases in body mass index (−0.5 kg/m2), weight (−1.2 kg), glucose (−0.14 mM) and HOMA (an estimate of insulin resistance, −0.21), and a decrease in insulin (−4.7 pmol/L) that approached significance (p = 0.0686). Ki67 staining in tumour tissue decreased significantly and TUNEL increased significantly. Levels of IR expression decreased significantly (from 4.39 to 3.82, p = 0.0375) as did the phosphorylation status of AKT (S473) and AMPK (T172) (from 9.82 to 7.08, p = <0.0001; from 6.2 to 5.1, p = 0.0034, respectively).

Conclusions: Metformin impact was consistent with beneficial anti-cancer effects. Reduced AKT phosphorylation, coupled with decreased insulin and IR levels, suggest insulin-dependent effects are important in the clinical setting. Assessment of additional factors in BC cells, including OCT1 expression (required for metformin uptake), and the phosphorylation of ACC (a marker of AMPK activation), is underway and will be reported. Integrated analysis of these factors combined with the physiological and molecular data described above will further enhance understanding of metformin action in the clinical setting.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD03-05.

Development of primary human nasal epithelial cell cultures for the study of cystic fibrosis pathophysiology

Cultured primary epithelial cells are used to examine inflammation in cystic fibrosis (CF). We describe a new human model system using cultured nasal brushings. Nasal brushings were obtained from 16 F508del homozygous patients and 11 healthy controls. Cells were resuspended in airway epithelial growth medium and seeded onto collagen-coated flasks and membranes for use in patch-clamp, ion transport, and mediator release assays. Viable cultures were obtained with a 75% success rate from subjects with CF and 100% from control subjects. Amiloride-sensitive epithelial Na channel current of similar size was present in both cell types while forskolin-activated CF transmembrane conductance regulator current was lacking in CF cells. In Ussing chambers, cells from CF patients responded to UTP but not to forskolin. Spontaneous and cytomix-stimulated IL-8 release was similar (stimulated 29,448 ± 9,025 pg/ml; control 16,336 ± 3,308 pg/ml CF; means ± SE). Thus nasal epithelial cells from patients with CF can be grown from nasal brushings and used in electrophysiological and mediator release studies in CF research.

PD04-09: Self-Reported Cognitive Attributes and Fatigue Improve over Long-Term Follow-Up in Breast Cancer Survivors; Some Cognitive Attributes Are Worse in Breast Cancer Survivors Than in Non-Cancer Controls

Background: Cognitive deficits and fatigue have been reported in breast cancer (BC) patients undergoing a variety of treatments, including chemotherapy; in some studies these concerns persist after completion of treatment. We examined these factors over time (median 11 yrs) in a longitudinal study of BC patients and compared the status of long-term BC survivors to non-BC controls.

Methods: 535 T1-3, N0-1, M0 BC patients were enrolled 1989–96; 260 women survived without metastases to participate in long-term follow-up (LTFU) measurements in 2006–8. 161 controls without BC were enrolled 2007–8. Questionnaires examined a range of QOL attributes; here we focus on items related to cognition and fatigue including: EORTC QLQ C30 (cognitive functioning, fatigue), Profile of Mood States (POMS — confusion/bewilderment, fatigue/inertia, vigor/activity), Fatigue Symptom Inventory (FSI — average fatigue past week, total disruption index), Everyday Problems (EDP — forgetfulness, difficulty concentrating, easily distracted). 166 of the BC patients had also completed EORTC and POMS at diagnosis and 1 year, and change in items on these questionnaires was calculated. Age and income adjusted differences between BC (LTFU) and controls were analyzed. Clinical significance was defined as ≥5% of the scale range or an effect size of ≥0.2 and statistical significance as P≤ 0.05.

Results: BC cases were older than controls (62.3 vs 59.1 yr), had lower education (24.6 vs 10.2% high school only) and family income (38.2 vs 19.8% < $60,000 annually) (all P<0.01). Cognitive attributes: BC patients showed clinically and statistically significant improvements between diagnosis and LTFU on POMS confusion/bewilderment but not EORTC cognitive functioning. Comparing BC (LTFU) to controls, in multivariate analyses adjusted for age and income, EORTC cognitive functioning (81.5 vs 87.4) and EDP forgetfulness (0.9 vs 0.6) were clinically and statistically significantly worse in BC patients than controls. In contrast, POMS confusion/bewilderment, EDP difficulty concentrating and EDP easily distracted scores were similar in BC patients at LTFU and controls. Fatigue: BC patients showed clinically and statistically significant improvements between diagnosis and LTFU on EORTC fatigue, POMS fatigue/inertia and POMS vigor/activity. After adjustment for age and income there were no clinically and statistically significant differences between BC (LTFU) and controls on any fatigue items.

Conclusions: Fatigue items, as well as some cognitive items, improved over time in BC patients and scores were comparable to scores in non-BC controls at LTFU. However, scores on some cognitive items were worse in LTFU BC patients than in non-BC controls raising concerns that BC diagnosis and treatment may be associated with long-term adverse effects on some aspects of self-reported cognitive attributes.

(Funded by The Breast Cancer Research Foundation)

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD04-09.

Abstract P5-13-09: Feasibility of a Randomized Controlled Trial of Vitamin D vs. Placebo in Recently Diagnosed Breast Cancer Patients

Background: Vitamin D (Vit D) supplementation is an area of interest in the primary and secondary prevention of many cancers. We previously reported a high prevalence of Vit D insufficiency and deficiency in newly diagnosed breast cancer (BC) patients. Low Vit D levels were associated with poor BC outcomes. Here we evaluate the state of Vit D adequacy and supplementation in a more recently diagnosed cohort of BC patients from 2 large urban centres, and we examine the feasibility of a placebo-controlled randomized trial (RCT) of supplementation in this population. Patients and Methods: Women diagnosed with T1-3, N0-3, M0 invasive BC within the previous 2 years were prospectively identified from institutional registries and recruited from Mount Sinai Hospital, Toronto and UCLA, Los Angeles (LA), between March 2009 and January 2010. Anthropometric measurements were performed, and dietary, lifestyle and medication histories were obtained using structured questionnaires and interviews. Tumor and treatment characteristics were obtained from clinical records; blood samples were collected for analysis of Vit D levels. The pre-specified feasibility criteria for a Vit D (vs placebo) RCT were: ≥30% of patients with (i) deficient or insufficient Vit D levels, (ii) taking ≥1000 IU Vit D/day and (iii) willing to participate in such a trial.

Results: 173 eligible patients were enrolled (80 Toronto, 93 LA). Median age at enrollment was 57 years; 73.4% were post-menopausal. Median tumor size (1.8 cm), lymph node involvement (39%), ER (80%), PR (65%) and Her2 (15%) positivity were similar between centres. Treatment characteristics including rates of mastectomy (44%), adjuvant chemotherapy (56%), radiation (68%), hormonal therapy (69%) and trastuzumab (14%) did not differ between centres. 84.4% of women reported use of Vit D containing supplements, with median daily doses of 1200 IU (Toronto) and 1400 IU (LA) (p=0.3) among users. Respective median 25-OH Vit D levels were 85.5 nmol/L (34.3 ng/mL) and 98.5 nmol/L (39.5 ng/mL) (p=0.04), and rates of deficiency, insufficiency and adequacy were 3.8%, 23.8%, 72.5% (Toronto) and 4.3%, 20.7%, 75.0% (LA) (p=0.88). No Vit D levels were in the toxic range. 25-OH Vit D levels correlated with Vit D supplement use (r=0.41, P<0.0001). 68% of women expressed willingness to participate in a Vit D RCT; however, only 12.7% of the study population met the pre-specified feasibility criteria.

Conclusions: Vit D levels and supplementation rates are substantially higher in these BC patients than in previous cohorts, though more than 25% of women do not have adequate levels. Rates of adequacy did not

differ between patients recruited in Toronto and LA. While the maj ority of women would be willing to participate in an RCT of Vit D supplementation, low levels of deficiency/insufficiency and high rates of supplement use may limit the feasibility of such a study. Funded by the Breast Cancer Research Foundation.

Activation of alpha1 and alpha2 noradrenergic receptors exert opposing effects on excitability of main olfactory bulb granule cells

The mammalian main olfactory bulb (MOB) receives a dense noradrenergic innervation from the pontine nucleus locus coeruleus that is important for neonatal odor preference learning and odor processing in mature animals. Modulation of GABAergic granule cells (GCs) is thought to play a key role in the net functional impact of norepinephrine (NE) release in the MOB, yet there are few direct studies of the influence of NE on these cells. In the present study we investigated noradrenergic modulation of GC excitability using electrophysiological approaches in rat MOB slices. A moderate concentration of NE (10 microM) and the alpha1 receptor agonist phenylephrine (10 microM) depolarized and increased spontaneous or current injection-evoked spiking in GCs. By contrast, low NE concentrations (0.1-1.0 microM) or the alpha2 receptor agonist clonidine (Clon, 10 microM) hyperpolarized and decreased the discharge of GCs. The effects of NE (10 microM) were blocked by antagonism of alpha1 and alpha2 receptors. Inhibitory effects of low NE concentrations were blocked or converted to excitatory responses by alpha2 receptor blockade, whereas excitatory effects of the moderate NE concentration were converted to inhibitory responses after alpha1 receptor blockade. NE (10 microM) and phenylephrine elicited inward currents that reversed near the potassium equilibrium potential. The effects of NE and phenylephrine were associated with increased membrane input resistance. Clonidine elicited an outward current associated with decreased membrane input resistance that reversed near the potassium equilibrium potential. These results indicate that alpha1 and alpha2 receptor activation exert opposing effects on GC excitability. Low concentrations of NE acting via alpha2 receptors suppress GC excitability, while higher concentrations of NE acting at alpha1 receptors increase GC excitability. These findings are consistent with recent findings that alpha1 and alpha2 receptor activation increase and decrease, respectively, GABAergic inhibition of mitral cells. The differential affinities of alpha1 and alpha2 noradrenergic receptor subtypes may allow for differential modulation of GABA release and olfactory processing as a function of the level of NE release, which in turn, is regulated by behavioral state.

Clinical phenotype of cystic fibrosis patients with the G551D mutation

BACKGROUND

Data on whether the phenotype of cystic fibrosis (CF) patients with compound heterozygocity for G551D (Gly551Asp) differs from patients with F508del (Phe508del) homozygous mutations is divergent.

AIM

We hypothesized that CF patients with the G551D mutation would have less severe disease than F508del homozygotes.

DESIGN

We compared the clinical phenotype of adult patients with a G551D mutation with adult patients homozygous for F508del and those with the missense mutation R117H (Arg117His). Compound heterozygotes for the G551D and R117H were analysed separately.

METHODS

Data were collected for 101 adult CF patients. Group 1-4 represents in order F508del homozygote patients (n = 61), those with the G551D mutation and a more severe mutation (n = 13), those with R117H mutation and a more severe mutation (n = 23) and also those compound for both the R117H and G551D mutations (n = 4).

RESULTS

Our findings have shown that adult patients with the G551D mutation and a second severe mutation have a milder clinical phenotype than F508del homozygous adult patients. Higher FEV(1) and body mass index and less impaired glucose tolerance was demonstrated in the patients with G551D and R117H compared to F508del homozygotes. There was a reduced yearly rate of decline of FEV(1) (P < 0.05), infection with Pseudomonas aeruginosa along with reduced burden of care. Compound heterozygosity for G551D and R117H mutations was associated with normal spirometry, body mass index, no chronic infection and no symptoms.

CONCLUSION

Mutations on different chromosomes are not independent of each other for the overall impact on the amount of functional CFTR. This study suggests that patients with the G551D mutation and a second severe mutation have a milder clinical phenotype than F508del homozygous patients, but the phenotype is not as mild as patients with the R117H mutation.