Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960

Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45° to 90°N but by less than 25% for 10° to 45°N. An increase of 30 to 60% in the seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear to signal large ecological changes in northern forests and a major shift in the global carbon cycle.

Patient preferences versus physician perceptions of treatment decisions in cancer care

PURPOSE

To examine patient preferences as well as physician perceptions of these preferences for decision making and communication in palliative care.

PATIENTS AND METHODS

Medical decision-making preferences (DMPs) were prospectively studied in 78 assessable cancer patients after initial assessment at a palliative care outpatient clinic. DMPs were assessed with a questionnaire using five possible choices ranging from 1 (patient prefers to make the treatment decision) to 5 (patient prefers the physician to make the decision). In addition, the physician's perception of this preference was assessed.

RESULTS

Full concordance between the physician and the patient was seen in 30 (38%) of 78 cases; when the five original categories were recombined to cover active, shared, and passive decision making, there was concordance in 35 (45%) of 78 cases. The kappa coefficient for agreement between physician and patient was poor at 0.14 (95% confidence limit, -0.01 to 0.30) for simple kappa and 0.17 (95% confidence interval [CI], 0.00 to 0.34) for weighted kappa (calculated on the three regrouped categories). Active, shared, and passive DMPs were chosen by 16 (20%) of 78, 49 (63%) of 78, and 13 (17%) of 78 patients, and by 23 (29%) of 78, 30 (39%) of 78, and 25 (32%) of 78 physicians, respectively. The majority of patients (49 [63%] of 78; 95% CI, 0.51 to 0.74) preferred a shared approach with physicians. Physicians predicted that patients preferred a less shared approach than they in fact did. Patient age or sex did not significantly alter DMP.

CONCLUSION

An individual approach is needed and each patient should be assessed prospectively for DMP.

The burden of chronic spontaneous urticaria is substantial: Real-world evidence from ASSURE-CSU

BACKGROUND

Chronic spontaneous urticaria (CSU) can be debilitating, difficult to treat, and frustrating for patients and physicians. Real-world evidence for the burden of CSU is limited. The objective of this study was to document disease duration, treatment history, and disease activity, as well as impact on health-related quality of life (HRQoL) and work among patients with inadequately controlled CSU, and to describe its humanistic, societal, and economic burden.

METHODS

This international observational study assessed a cohort of 673 adult patients with CSU whose symptoms persisted for ≥12 months despite treatment. Demographics, disease characteristics, and healthcare resource use in the previous 12 months were collected from medical records. Patient-reported data on urticaria and angioedema symptoms, HRQoL, and work productivity and activity impairment were collected from a survey and a diary.

RESULTS

Almost 50% of patients had moderate-to-severe disease activity as reported by Urticaria Activity Score. Mean (SD) Dermatology Life Quality Index and Chronic Urticaria Quality of Life Questionnaire scores were 9.1 (6.62) and 33.6 (20.99), respectively. Chronic spontaneous urticaria markedly interfered with sleep and daily activities. Angioedema in the previous 12 months was reported by 66% of enrolled patients and significantly affected HRQoL. More than 20% of patients reported ≥1 hour per week of missed work; productivity impairment was 27%. These effects increased with increasing disease activity. Significant healthcare resources and costs were incurred to treat CSU.

CONCLUSIONS

Chronic spontaneous urticaria has considerable humanistic and economic impacts. Patients with greater disease activity and with angioedema experience greater HRQoL impairments.

Delayed early embryonic lethality following disruption of the murine cyclin A2 gene

In higher eukaryotes, cell cycle progression is controlled by cyclin dependent kinases (Cdks) complexed with cyclins. A-type cyclins are involved at both G1/S and G2/M transitions of the cell cycle. Cyclin A2 activates cdc2 (Cdk1) on passage into mitosis and Cdk2 at the G1/S transition. Antisense constructs, or antibodies directed against cyclin A2 block cultured mammalian cells at both of these transitions. In contrast, overexpression of cyclin A2 appears to advance S phase entry and confer anchorage-independent growth, and can lead to apoptosis. A second A-type cyclin, cyclin A1 has been described recently which, in the mouse, is expressed in germ cells but not somatic tissues. To address the possible redundancy between different cyclins in vivo and also the control of early embryonic cell cycles, we undertook the targeted deletion of the murine cyclin A2 gene. The homozygous null mutant is embryonically lethal, demonstrating that the cyclin A2 gene is essential. Surprisingly, homozygous null mutant embryos develop normally until post-implantation, around day 5.5 p.c. This observation may be explained by the persistence of a maternal pool of cyclin A2 protein until at least the blastocyst stage, or an unexpected role for cyclin A1 during early embryo development.

A distinct cyclin A is expressed in germ cells in the mouse

In this paper, the existence of two A-type cyclins in the mouse is demonstrated. In the adult mouse, the expression of cyclin A1, which has greatest sequence identity with Xenopus cyclin A1, is restricted to germ cells. In contrast cyclin A2, which has greatest sequence identity with human cyclin A and Xenopus cyclin A2, is expressed in all tissues analysed. In order to explore the function of cyclin A1 in germ cells, its expression during the meiotic cell cycle and its associated kinase subunits have been characterised in the testis. The levels of cyclin A1 mRNA rise dramatically in late pachytene spermatocytes and become undetectable soon after completion of the meiotic divisions; thus its expression is cell cycle regulated. In lysates of germ cells from adult testes, cyclin A1 is present in p13suc1 precipitates, and cyclin A1 immunoprecipitates possess histone H1 kinase activity. Three kinase partners of cyclin A1 were identified: p34cdc2, a polypeptide of 39 × 10(3) M(r) that is related to p33cdk2 and, in lesser quantities, p33cdk2. Cyclin A1 was also detected in oocytes; in metaphase I and metaphase II oocytes, a proportion of the cyclin A1 colocalises with the spindle, possibly suggestive of a functional interaction. These data indicate that mammalian germ cells contain cyclin A1-dependent kinases that either act as a substitute for, or in addition to, the cyclin A2-dependent kinases characterised in somatic tissues.

Gastroesophageal reflux disease, use of H2 receptor antagonists, and risk of esophageal and gastric cancer

OBJECTIVE

The incidence of esophageal adenocarcinoma has risen rapidly in the past two decades, for unknown reasons. The goal of this analysis was to determine whether gastroesophageal reflux disease (GERD) or the medications used to treat it are associated with an increased risk of esophageal or gastric cancer, using data from a large population-based case-control study.

METHODS

Cases were aged 30-79 years, newly diagnosed with esophageal adenocarcinoma (n = 293), esophageal squamous cell carcinoma (n = 221), gastric cardia adenocarcinoma (n = 261), or non-cardia gastric adenocarcinoma (n = 368) in three areas with population-based tumor registries. Controls (n = 695) were chosen by random digit dialing and from Health Care Financing Administration rosters. Data were collected using an in-person structured interview.

RESULTS

History of gastric ulcer was associated with an increased risk of non-cardia gastric adenocarcinoma (OR 2.1, 95% CI 1.4-3.2). Risk of esophageal adenocarcinoma increased with frequency of GERD symptoms; the odds ratio in those reporting daily symptoms was 5.5 (95% CI 3.2-9.3). Ever having used H2 blockers was unassociated with esophageal adenocarcinoma risk (OR 0.9, 95% CI 0.5-1.5). The odds ratio was 1.3 (95% CI 0.6-2.8) in long-term (4 or more years) users, but increased to 2.1 (95% CI 0.8-5.6) when use in the 5 years prior to the interview was disregarded. Risk was also modestly increased among users of antacids. Neither GERD symptoms nor use of H2 blockers or antacids was associated with risk of the other three tumor types.

CONCLUSIONS

Individuals with long-standing GERD are at increased risk of esophageal adenocarcinoma, whether or not the symptoms are treated with H2 blockers or antacids.

Growth factor-specific signaling pathway stimulation and gene expression mediated by ErbB receptors

The mechanisms by which receptor tyrosine kinases (RTKs) utilize intracellular signaling pathways to direct gene expression and cellular response remain unclear. A current question is whether different RTKs within a single cell target similar or different sets of genes. In this study we have used the ErbB receptor network to explore the relationship between RTK activation and gene expression. We profiled growth factor-stimulated signaling pathway usage and broad gene expression patterns in two human mammary tumor cell lines expressing different complements of ErbB receptors. Although the growth factors epidermal growth factor (EGF) and neuregulin (NRG) 1 similarly stimulated Erk1/2 in MDA-MB-361 cells, EGF acting through an EGF receptor/ErbB2 heterodimer preferentially stimulated protein kinase C, and NRG1beta acting through an ErbB2/ErbB3 heterodimer preferentially stimulated Akt. The two growth factors regulated partially overlapping yet distinct sets of genes in these cells. In MDA-MB-453 cells, NRG1beta acting through an ErbB2/ErbB3 heterodimer stimulated prolonged signaling of all pathways examined relative to NRG2beta acting through the same heterodimeric receptor species. Surprisingly, NRG1beta and NRG2beta also regulated partially overlapping but distinct sets of genes in these cells. These results demonstrate that the activation of different RTKs, or activation of the same RTKs with different ligands, can lead to distinct profiles of gene regulation within a single cell type. Our observations also suggest that the identity and kinetics of signaling pathway usage by RTKs may play a role in the selection of regulated genes.

The phosphatidylinositol-3 kinase pathway regulates bladder cancer cell invasion

OBJECTIVES

To investigate the role of the phosphatidylinositol (PI)-3 kinase pathway in the invasion of bladder cancer cell lines, and to assess the activation of this pathway in primary human bladder tumours.

MATERIALS AND METHODS

Human bladder cancer cells were treated with pathway specific inhibitors or were transfected with PI-3 kinase pathway components. The invasion of cultured bladder cancer cells was analysed by an invasion assay. Bladder cancer cells lines and primary human bladder tumours were analysed for pathway activation by western blotting.

RESULTS

A specific inhibitor of PI-3 kinase enzyme activity, Ly294002, potently suppressed the invasive properties of three highly invasive bladder tumour cell lines. Restoration of the PTEN gene to invasive UM-UC-3 bladder tumour cells or expression of a dominant-negative version of the PI-3 kinase target, Akt, also potently inhibited invasion, indicating a central role for the PI-3 kinase/Akt pathway in this process. In addition, 55% of primary tumours from patients with bladder cancer had markedly high levels of phosphorylated Akt.

CONCLUSION

Pharmacological or biochemical inhibition of the PI-3 kinase pathway drastically reduced the invasive capacity of bladder cancer cell lines; over half of primary human bladder tumours had high Akt phosphorylation, suggesting that the aberrant activation of this pathway may contribute to the invasion of a significant subset of bladder cancers.

Ligand discrimination in signaling through an ErbB4 receptor homodimer

The epidermal growth factor (EGF)-like family of growth factors elicits cellular responses by stimulating the dimerization, autophosphorylation, and tyrosine kinase activities of the ErbB family of receptor tyrosine kinases. Although several different EGF-like ligands are capable of binding to a single ErbB family member, it is generally thought that the biological and biochemical responses of a single receptor dimer to different ligands are indistinguishable. To test whether an ErbB receptor dimer is capable of discriminating among ligands we have examined the effect of four EGF-like growth factors on signaling through the ErbB4 receptor homodimer in CEM/HER4 cells, a transfected human T cell line ectopically expressing ErbB4 in an ErbB-null background. Despite stimulating similar levels of gross receptor tyrosine phosphorylation, the EGF-like growth factors betacellulin, neuregulin-1beta, neuregulin-2beta, and neuregulin-3 exhibited different biological potencies in a cellular growth assay. Moreover, the different ligands induced different patterns of recruitment of intracellular signaling proteins to the activated receptor and induced differential usage of intracellular kinase signaling cascades. Finally, two-dimensional phosphopeptide mapping of ligand-stimulated ErbB4 revealed that the different growth factors induce different patterns of receptor tyrosine phosphorylation. These results indicate that ErbB4 activation by growth factors is not generic and suggest that individual ErbB receptors can discriminate between different EGF-like ligands within the context of a single receptor dimer. More generally, our observations significantly modify our understanding of signaling through receptor tyrosine kinases and point to a number of possible models for ligand-mediated signal diversification.

The role of human glutathione S-transferases (hGSTs) in the detoxification of the food-derived carcinogen metabolite N-acetoxy-PhIP, and the effect of a polymorphism in hGSTA1 on colorectal cancer risk

Food-derived heterocyclic amines (HCAs), particularly 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), are implicated in the etiology of human colorectal cancer (CRC) via a process of N-oxidation followed by O-acetylation or O-sulfation to form electrophilic metabolites that react with DNA. Glutathione S-transferases (GSTs) detoxify activated carcinogen metabolites by catalysis of their reaction with GSH. However, among HCAs, only N-acetoxy-PhIP has been shown to be a substrate for the GSTs. By using a competitive DNA-binding assay, we confirm that hGSTA1-1 is an efficient catalyst of the detoxification of N-acetoxy-PhIP. Further, we show that hGSTs A2-2, P1-1, M1-1, T1-1 and T2-2 appear to have low activity towards N-acetoxy-PhIP, and that hGSTs A4-4, M2-2, M4-4 and Z1-1 appear to have no activity towards N-acetoxy-PhIP. A genetic polymorphism in the 5'-regulatory sequence of hGSTA1 has been shown to correlate with the relative and absolute levels of expression of GSTA1/GSTA2 in human liver. Examination of hGSTA1 allele frequency in 100 Caucasian CRC patients and 226 Caucasian controls demonstrated a significant over-representation of the homozygous hGSTA1*B genotype among cases compared to controls (24.0 and 13.7%, respectively, P=0.04). This corresponds to an odds ratio for risk of CRC of 2.0 (95% CI 1.0-3.7) when comparing homozygous hGSTA1*B individuals with all other genotypes. Thus, individuals who are homozygous hGSTA1*B, and who would be predicted to have the lowest levels of hGSTA1 expression in their livers, appear to be at risk of developing CRC, possibly as a result of inefficient hepatic detoxification of N-acetoxy-PhIP.

CYP1A1, cigarette smoking, and colon and rectal cancer

Cytochrome P-450 (CYP) is involved in the activation and metabolism of polycyclic aromatic hydrocarbons in tobacco products. The authors evaluated the association of two polymorphisms in the CYP1A1 gene--the noncoding Msp I polymorphism in the 3'-untranslated region and the Ile462Val polymorphism in exon 7--with colon and rectal cancer. The authors used data from two incident case-control studies of colon cancer (1,026 cases and 1,185 controls) and rectal cancer (820 cases and 1,036 controls) conducted in California and Utah (1991-2002). CYP1A1 genotype was not associated with colon or rectal cancer. Having GSTM1 present, a CYP1A1 variant allele, and the rapid-acetylator NAT2 imputed phenotype was associated with increased risk of colon cancer (odds ratio = 1.7, 95% confidence interval: 1.2, 2.3). Among men, the greatest colon cancer risk was observed for having any CYP1A1 variant allele and currently smoking (odds ratio = 2.5, 95% confidence interval: 1.3, 4.8; Wald chi(2)test: p < 0.01). Assessment of GSTM1 and CYP1A1 and rectal cancer in men showed a twofold elevation in risk for more than 20 pack-years of smoking, except among those with GSTM1 present who had a variant CYP1A1 allele. These data support the association between smoking and colon and rectal cancer. Smoking may have a greater impact on colorectal cancer risk based on CYP1A1 genotype; this might further be modified by GSTM1 for rectal cancer risk.

Angioedema in chronic spontaneous urticaria is underdiagnosed and has a substantial impact: Analyses from ASSURE-CSU

Background

ASSURE‐CSU revealed differences in physician and patient reporting of angioedema. This post hoc analysis was conducted to evaluate the actual rate of angioedema in the study population and explore differences between patients with and without angioedema.

Methods

This international observational study assessed 673 patients with inadequately controlled chronic spontaneous urticaria (CSU). Physicians abstracted angioedema data from medical records, which were compared with patient‐reported data. Patients in the Yes‐angioedema category had angioedema reported in the medical record and a patient‐reported source. For those in the No‐angioedema category, angioedema was reported in neither the medical record nor a patient‐reported source. Those in the Misaligned category had angioedema reported in only one source. Statistical comparisons between Yes‐angioedema and No‐angioedema categories were conducted for measures of CSU activity, health‐related quality of life (HRQoL), productivity and healthcare resource utilization (HCRU). Regression analyses explored the relationship between Dermatology Life Quality Index (DLQI) score and angioedema, adjusting for important covariates.

Results

Among evaluable patients, 259 (40.3%), 173 (26.9%) and 211 (32.8%) were in the Yes‐angioedema, No‐angioedema and Misaligned category, respectively. CSU activity and impact on HRQoL, productivity, and HCRU was greater for Yes‐angioedema patients than No‐angioedema patients. After covariate adjustment, mean DLQI score was significantly higher (indicating worse HRQoL) for patients with angioedema versus no angioedema (9.88 vs 7.27, P < .001). The Misaligned category had similar results with Yes‐angioedema on all outcomes.

Conclusions

Angioedema in CSU seems to be under‐reported but has significant negative impacts on HRQoL, daily activities, HCRU and work compared with no angioedema.

Rapid diagnosis of leishmaniasis by fluorogenic polymerase chain reaction

A fluorescent DNA probe (LEIS.P1) specific for a conserved region of the small-subunit ribosomal RNA gene of Leishmania and a pair of flanking primers (LEIS.U1 and LEIS.L1) were designed for use in a fluorogenic polymerase chain reaction. Optimal assay conditions with zero background were established to detect low levels of Leishmania from clinical samples. By use of this assay, we amplified DNA from 27 strains of cultured Leishmania (both Old and New World strains) and selectively amplified Leishmania DNA from 12 paraffin-embedded human biopsy samples and 3 fresh human skin biopsy specimens. For the fresh human tissue biopsies, the turnaround time from biopsy to test result was < 24 hr. No amplification was detected in negative control samples (including the kinetoplastid protozoa Trypanosoma rangelli and Crithidia fasiculata). This assay provides a specific and rapid diagnostic modality to detect infection with Leishmania.

Ligand discrimination by ErbB receptors: differential signaling through differential phosphorylation site usage

The four members of the ErbB family of receptor tyrosine kinases (RTKs) mediate a variety of cellular responses to epidermal growth factor (EGF)-like growth factors, and serve as a model for the generation of both diversity and specificity in RTK signaling. Previous studies indicate that receptor-receptor interactions figure prominently in signaling through ErbB receptors. In addition to a role in receptor kinase activation, ligand-induced ErbB receptor homo- and heterodimerization is thought to account for the diversity of biological responses stimulated by EGF-like growth factors. Since each receptor has the potential to couple to different complements of signaling pathways, EGF-like ligands specify cellular response by dictating which pairs of receptors become activated. More recently evidence has been uncovered for ligand discrimination by individual ErbB receptor dimers; receptors appear to realize which ligand is binding and differentially respond through autophosphorylation site usage. These observations indicate that ligand stimulation of RTKs is not generic, and point to another layer in the ErbB signal diversification mechanism. The mechanistic implications of ligand discrimination are discussed.

Cachexia and asthenia in cancer patients

Over the past 10 years, there have been major advances in the understanding of cancer cachexia and asthenia. These common complications of cancer are now thought to be the consequences of complex interactions between host, tumour, and psychosocial factors. Cachexia and asthenia commonly coexist, but they can occur independently of each other. Recently identified tumour-derived factors cause lipolysis and protein catabolism. Cytokines produced by the host in response to tumour presence cause metabolic abnormalities, which result in decreased protein and lipid synthesis, increased lipolysis, and anorexia. Many other factors contribute to asthenia, such as anaemia, autonomic failure, and muscular abnormalities. Future research should clarify optimum management. The way forward seems to lie in a multidimensional approach with combined therapy to manage both cancer cachexia and asthenia.

Cavernous haemangiomas (angiomas) of the brain: clinically significant lesions

A review of 2000 consecutive magnetic resonance imaging (MRI) brain studies identified 18 (0.9%) patients with lesions that satisfied MRI criteria for cavernous haemangiomas. The clinical, computed tomography (CT) and MRI findings in 23 patients with probable cavernous haemangiomas were compared. Thirty-three lesions were identified with multiple lesions in five (22%) patients. In 19 (82%) patients the neurological presentation corresponded to a cavernous haemangioma. The presenting symptoms were: seizures in 11 patients (48%); progressive neurological symptoms and signs in four (17%); and acute symptoms and signs due to haemorrhage in four (17%). T2 weighted images suggested the diagnosis in all cases, with 24 (73%) lesions showing the typical appearance of an area of mixed signal intensity with a rim of low signal intensity. In the absence of acute haemorrhage, CT demonstrated well circumscribed, round or oval hyperdense lesions without significant mass effect and with normal surrounding brain tissue in the majority of cases. Although not diagnostic, these CT features are strongly suggestive of cavernous haemangiomas.

Localization and modulation of ErbB receptor tyrosine kinases

The ErbB family of receptor tyrosine kinases serves as a model for understanding the propagation of growth factor signals across the plasma membrane and the interpretation of those signals into a cellular response. Recent studies point to a critical role for the accumulation of ErbBs at specific cell-surface locations in the fidelity of ErbB signaling. The past year has witnessed significant advances in our understanding of the molecular mechanisms of ErbB localization and the role of PDZ-domain-containing proteins and cell-surface glycoproteins in directly modulating signaling through ErbBs.

Membrane Mucin Muc4 promotes blood cell association with tumor cells and mediates efficient metastasis in a mouse model of breast cancer

Mucin-4 (Muc4) is a large cell surface glycoprotein implicated in the protection and lubrication of epithelial structures. Previous studies suggest that aberrantly expressed Muc4 can influence the adhesiveness, proliferation, viability and invasiveness of cultured tumor cells, as well as the growth rate and metastatic efficiency of xenografted tumors. Although it has been suggested that one of the major mechanisms by which Muc4 potentiates tumor progression is via its engagement of the ErbB2/HER2 receptor tyrosine kinase, other mechanisms exist and remain to be delineated. Moreover, the requirement for endogenous Muc4 for tumor growth progression has not been previously explored in the context of gene ablation. To assess the contribution of endogenous Muc4 to mammary tumor growth properties, we first created a genetically engineered mouse line lacking functional Muc4 (Muc4ko), and then crossed these animals with the NDL (Neu DeLetion mutant) model of ErbB2-induced mammary tumorigenesis. We observed that Muc4ko animals are fertile and develop normally, and adult mice exhibit no overt tissue abnormalities. In tumor studies, we observed that although some markers of tumor growth such as vascularity and cyclin D1 expression are suppressed, primary mammary tumors from Muc4ko/NDL female mice exhibit similar latencies and growth rates as Muc4wt/NDL animals. However, the presence of lung metastases is markedly suppressed in Muc4ko/NDL mice. Interestingly, histological analysis of lung lesions from Muc4ko/NDL mice revealed a reduced association of disseminated cells with platelets and white blood cells. Moreover, isolated cells derived from Muc4ko/NDL tumors interact with fewer blood cells when injected directly into the vasculature or diluted into blood from wild type mice. We further observed that blood cells more efficiently promote the viability of non-adherent Muc4wt/NDL cells than Muc4ko/NDL cells. Together, our observations suggest that Muc4 may facilitate metastasis by promoting the association of circulating tumor cells with blood cells to augment tumor cell survival in circulation.

Genetic variation in IGF1, IGFBP3, IRS1, IRS2 and risk of breast cancer in women living in Southwestern United States

BACKGROUND

An insulin-related pathway to breast cancer has been hypothesized.

METHODS

We examine the 19 CA repeat of the IGF1 gene, the -202 C > A IGFBP3, the G972R IRS, and the G1057D IRS2 polymorphisms among 1,175 non-Hispanic white (NHW) and 576 Hispanic newly diagnosed breast cancer cases and 1,330 NHW and 727 Hispanic controls living in Arizona, Colorado, New Mexico, and Utah.

RESULTS

Among post-menopausal women not recently exposed to hormones, not having the 19 CA repeat of IGF1 gene was associated with breast cancer among NHW women [odds ratio (OR) 2.14, 95% confidence interval (CI) 1.21-3.79] and having an R allele of G972R IRS1 increased breast cancer risk among Hispanic women (OR 2.70, 95% CI 1.13-6.46). Among post-menopausal Hispanic women recently exposed to hormones the A allele of the -202 C > A IGFBP3 polymorphism increased risk of breast cancer (OR 1.57, 95% CI 1.06-2.33). The IGF1 19 CA repeat polymorphism interacted with hormone replacement therapy (HRT) among NHW post-menopausal women; women who had the 19/19 IGF1 genotype were at reduced risk of breast cancer (OR 0.64, 95% CI 0.47-0.88) if they did not use HRT. We also observed interaction between body mass index and IGF1 19 CA repeat (p=0.06) and between weight gain and the -202 C > A IGFBP3 polymorphism (p=0.05) in NHW post-menopausal women not recently exposed to hormones.

CONCLUSIONS

Our data suggest that associations between insulin-related genes and breast cancer risk among women living in the Southwestern United States may be dependent on estrogen exposure and may differ by ethnicity.