Downregulation of endogenous intermedin augmented myocardial injury in rats with ischemia/reperfusion

Intermedin (IMD) plays an important regulatory role in cardiovascular function. We aimed to explore the protein expression of IMD and its receptors, calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs), and the role of endogenous IMD in myocardial ischemia/reperfusion (I/R) injury in rats. The rat model of I/R was created by ligating cardiac left anterior descending artery. Western blot was used to determine protein expression of CRLR and RAMPs, and radioimmunoassay was used to detect IMD content. Compared with control, protein levels of CRLR and RAMPs in both ischemic and nonischemic region were upregulated at different stages of reperfusion. IMD protein content in nonischemic area myocardium also increased. However, IMD protein content in ischemic area downregulated at 3-, 6-, and 12-h reperfusion. In hypoxia/reoxygenation model of neonatal cardiomyocytes, IMD attenuated myocyte injury, and IMD receptor antagonist IMD17-47 aggravated myocyte impairment by blocking endogenous IMD. In conclusion, the downregulation of IMD at early stage of reperfusion might augment myocardium injury.

Firing patterns in a conductance-based neuron model: bifurcation, phase diagram, and chaos

Responding to various stimuli, some neurons either remain resting or can fire several distinct patterns of action potentials, such as spiking, bursting, subthreshold oscillations, and chaotic firing. In particular, Wilson's conductance-based neocortical neuron model, derived from the Hodgkin-Huxley model, is explored to understand underlying mechanisms of the firing patterns. Phase diagrams describing boundaries between the domains of different firing patterns are obtained via extensive numerical computations. The boundaries are further studied by standard instability analyses, which demonstrates that the chaotic neural firing could develop via period-doubling and/or period- adding cascades. Sequences of the firing patterns often observed in many neural experiments are also discussed in the phase diagram framework developed. Our results lay the groundwork for wider use of the model, especially for incorporating it into neural field modeling of the brain.

Human papillomavirus type 16 infection may be involved in esophageal squamous cell carcinoma carcinogenesis in Chinese Kazakh patients

The aim of this study was to investigate human papillomavirus type 16 (HPV16) prevalence in esophageal squamous cell carcinoma (ESCC) in Xinjiang Kazakh patients and its role in ESCC carcinogenesis. One hundred and fifty cases of ESCC and 150 cases of corresponding normal esophageal mucosa (CNGM) samples were collected from north Xinjiang where the Kazakh ethnic group has lived since ancient times. HPV16 infection in ESCC and CNGM was detected by genotype-specific polymerase chain reaction. HPV16 DNA was detected in 55 of 150 ESCC samples (36.7%) and 24 of 150 corresponding normal esophageal mucosa samples (16%) with significant differences (P < 0.001, odds ratio = 3.039, 95% confidence interval: 1.756-5.260). No statistically significant correlations were found between HPV16 infection and the age or gender of patients, tumor site, tumor cell differentiation, or lymph node metastasis (P > 0.05). HPV16 infection is common in cases of ESCC in the Kazakh ethnic group in Xinjiang and may be involved in ESCC carcinogenesis.

Effects of subacute exposure to 1,2-dichloroethane on mouse behavior and the related mechanisms

The aim of this study was to explore the effects of subacute exposure to 1,2-dichloroethane (1,2-DCE) on mouse behavior and the related mechanisms focusing on alteration of oxidative stress and amino acid neurotransmitters in the brain. Mouse behavior was examined by open field test. Levels of nitric oxide (NO), malondialdehyde (MDA) and nonprotein sulfhydryl (NPSH) and activity of inducible nitric oxide synthase (iNOS) and superoxide dismutase (SOD) were determined by colorimetric method. Contents of glutamate (Glu), aspartate (Asp) and gamma-aminobutyric acid (GABA) were evaluated by high-performance liquid chromatography. Reduced locomotor and exploratory activities and increased anxiety were found in 0.45 and 0.9 g/m3 1,2-DCE-treated mice. In contrast, increased excitability was found in 0.225 g/m3 1,2-DCE-treated mice. Compensatory antioxidant status and increased NOS activity and NO level in the brain were found in 1,2-DCE-treated mice. Moreover, Glu contents in 1,2-DCE-treated mice and GABA contents in 0.9 g/m3 1,2-DCE-treated mice increased, whereas GABA contents in 0.225 g/m3 1,2-DCE-treated mice decreased significantly compared with control. Taken together, our results suggested that mouse behavior could be disturbed by subacute exposure to 1,2-DCE, and the changes of amino acid neurotransmitter in the brain might be related to the behavioral effects.

Liquid immiscibility in an Fe-Cu alloy by molecular dynamics simulation

Liquid-liquid phase segregation in an Fe-Cu melt is investigated by molecular dynamics (MD) simulation based upon a newly developed embedded atom method due to Bonny. The partial pair correlation functions (PPCF) of liquid Fe(50)Cu(50) at a temperature of 1873 K show stronger interaction of homogeneous atom pairs. The coordination number (CN) of Cu-Cu and Fe-Fe in Fe(50)Cu(50) melt is about 11, much higher than that of Fe-Cu. Liquid-liquid phase segregation has also been observed clearly by the atom snapshot method. The calculated enthalpy of mixing is positive in the whole concentration range and the Bhatia-Thornton (BT) structure factor S(CC)(q) increases sharply at lower q, which are all typical features of dense fluid that exhibits a phase segregation tendency. Our present work provides an understanding of atomic-scale phase segregation in liquid Fe-Cu alloy.

Anchoring platinum on graphene using metallic adatoms: a first principles investigation

First principles calculations based on spin-polarized density functional theory were used to identify metallic adatoms that would strengthen the Pt(111)/graphene interface (with a low work of separation of 0.009 J m(-2)), when the adatom was placed between the Pt(111) and the graphene. It was shown that the strength of the Pt-adatom bond, which had a metallic character, increased with the amount of charge transferred from the adatom to the Pt. The carbon-adatom bond, on the other hand, had a mixed ionic and covalent character and was weaker than the Pt-adatom bond for each of the 25 elements considered. Consequently, the total Pt(111)/graphene interface strength and, hence, the anchoring effect of the adatom were controlled by the carbon-adatom bond strength. Metals with unfilled d orbitals increased the Pt/graphene interface strength to above 0.5 J m(-2). The carbon-adatom bond strength was proportional to the ratio between the charge transferred from the adatom to the graphene (ΔZ(C)) and the charge transferred to the Pt surface (ΔZ(Pt)); i.e., the ΔZ(C)/ΔZ(Pt) ratio defined the ability of an adatom to anchor Pt to graphene. For Ir, Os, Ru, Rh and Re, ΔZ(C)/ΔZ(Pt) > 1.0, making these elements the most effective adatoms for anchoring Pt to graphene.

Effect of neferine on liver ischemia-reperfusion injury in rats

INTRODUCTION

Liver ischemia/reperfusion leads to the formation of reactive oxygen species (ROS) that cause liver injury, a critical clinical problem during liver surgery and transplantation. The aim of the present study was to investigate the hepatoprotective and antioxidant effects of neferine against liver ischemia/reperfusion injury in rats.

MATERIALS AND METHODS

Wistar rats were randomly divided into 4 groups (n = 8): sham group; model group, and neferine high and low groups (50 and 25 mg/kg, respectively). After either saline or neferine was orally administered for 5 days rat livers were subjected to 30 minutes of ischemia followed by 6 hours of reperfusion. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hydroxyl radical levels were measured in serum. The liver was removed to assay malondialdehyde (MDA) and carbonyl contents, superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities, as well as to evaluate histopathologic changes.

RESULTS

Neferine significantly prevented AST and ALT elevations, reduced hydroxyl radical release, inhibited SOD and GPx activities, and decreased MDA and carbonyl contents. At the same time, neferine attenuated the histopathologic changes.

CONCLUSION

Neferine protected against liver ischemia/reperfusion in rats through antioxidant mechanisms. However, further studies are needed to verify whether the hepatoprotection of neferine is correlated with anti-inflammatory and anti-apoptotic effects.

P4-16-02: Problems with Identifying Bone Metastasis-Specific Genes without Considering Biological Differences between ER-Positive and ER-Negative Breast Cancers

Background: Bone metastasis-specific genes in breast cancer have been reported without considering the significant differences in ER status between bone and non-bone metastases. The aims of this study were to validate genes that had been reported as bone metastasis-specific genes using our data set and to identify bone metastasis-specific genes on the basis of biological differences between ERpositive and ER-negative breast cancers.

Patients and Methods: We used Affymetrix GeneChip arrays to analyze tumor samples obtained from 365 primary invasive breast cancer patients who underwent surgery from 1999 to 2008. We excluded patients with HER2−positive breast cancer (normalized HER2 mRNA expression [probe set 216836_s_at] &gt; 12.54). We classified the samples into 3 cohorts according to first metastatic site: bone, non-bone, or no metastasis. Differential expression of genes between bone and non-bone cohorts that were differentially expressed was identified using the Cox proportional hazards model, and gene sets was assessed using gene-set analysis.

Results: Of the 365 patients, 34 (9.3%) were included in the bone cohort and 32 (8.8%) in the non-bone cohort. Two hundred fourteen (58.6%) had ER-positive and 151 (41.4%) had ER-negative breast cancer. First, we performed gene-set analysis using 5 gene sets that had been reported to be associated with bone metastasis. One gene set, which had been detected using an ER-negative breast cancer cell line, was validated as predicting bone metastasis in ER-positive breast cancer. None of the 5 gene sets predicted bone metastasis in ER-negative breast cancer. We then determined the levels of individual genes associated with bone metastasis by ER status using all 16,712 probe sets filtered by average gene expression level. When we analyzed all patients without any stratification by ER status, as in previous studies, 592 probe sets were significantly overexpressed in the bone cohort compared with the non-bone cohort, with a false discovery rate of ≤0.05. However, when we analyzed ER-positive and ER-negative breast cancers separately, no genes were found with significant differences between bone and non-bone cohorts. Finally, we used 2,246 functionally annotated gene sets assembled from Gene Ontology to examine possible biological differences between bone and non-bone cohorts. In the bone cohort, 151 and 125 gene sets were significantly overexpressed in ER-positive and ER-negative breast cancers, respectively (P ≤ 0.05). Ppathways related to Cellular growth and proliferation, and intracellular and second-messenger signaling were overexpressed in ER-positive breast cancer, whereas pathways related to nuclear receptor and cytokine signaling were overexpressed in ER-negative breast cancer. Most bone-metastasis-related pathways were different in ER-positive and ER-negative breast cancers (91.4% and 89.6% of the gene sets, respectively).

Discussion: No genes were found that can predict bone metastasis. ER-positive and ER-negative breast cancers have different biological potentials for bone metastasis. Therefore, we need to assess the prediction model of bone metastasis based on the biological features for each ER status separately.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-16-02.

P1-07-09: Estrogen Receptor (ER) mRNA and ER-Related Gene Expression in Breast Cancers That Are 1%-10% ER-Positive by Immunohistochemistry

Purpose: Our goal was to examine whether borderline estrogen receptor (ER)-positive cancers, defined as 1–10% positivity by immunohistochemistry (IHC), show the same global gene expression pattern and high ESR1 mRNA expression as ER-positive cancers or are more similar to ER-negative cancers.

Patients and methods: ER status was determined by IHC in 465 primary breast cancers and with Affymetrix U133A gene chip (ESR1 mRNA gene expression: Probe set = 205225_at). We compared expressions of ESR1 mRNA and a 106-probe set ER-associated gene signature score between ER-negative (n=183), 1–9% (n=25), exactly 10% (n=6), and &gt; 10% ER-positive (n=251) cancers. We also assessed the molecular class of the borderline ER-positive cases using the PAM-50 classifier.

Results: Among the 1–9%, 10% and &gt; 10% IHC positive cases, 24%, 67% and 92% were also ER-positive by ESR1 mRNA expression. The average ESR1 expression was significantly higher in the &gt; 10% IHC-positive cohorts compared to the 1–9% or completely negative cases but in these latter two cohorts ER expression was similarly low. The average ER gene signature scores were similar for the ER-negative and 1–9% IHC-positive cases, but significantly lower than in &gt; 10% ER-positive cases. None of the 1–9% ER-positive cases were classified as Luminal A, 2 were Luminal B and 12 were Basal-like. Among the 10% ER-positive cases, 2 were Luminal A and 1 was Luminal B. Conclusion: Overall, 24% of the 1–9% and 67% of the 10% ER-positive cancers show ESR1 mRNA levels and gene signatures that are consistent with ER-positive, potentially endocrine sensitive tumors.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-07-09.

P3-17-01: ApoE and Its Receptors (LRP8, VLDLR) Function as Growth Signals for Triple-Negative Breast Cancer and Represent a Novel Therapeutic Target

Triple-negative breast cancers (TNBC) lack the expression of estrogen, progesterone, and the human epidermal growth factor 2 receptors and have limited treatment options. We hypothesized that genes that are frequently amplified or overexpressed in these cancers are functionally important for the growth and survival of triple-negative breast cancer.

Materials/Methods: We identified genes overexpressed in TNBC in 3 different human breast cancer gene expression data sets (n=294, n=286, n=198). We assessed the functional importance of the consistently overexpressed genes using siRNA screen on 18 breast cancer cell lines (10 ER-, 8 ER+) in vitro. We targeted each gene with 4 different siRNA constructs separately and each experiment was performed in triplicate. The genes with the greatest TNBC-specific inhibitory effect after siRNA down regulation were selected for further mechanistic and signal transduction studies.

Results: 684 genes showed consistent and highly significant overexpression in TNBC compared to receptor-positive cancers in all 3 data sets. siRNA suppression of 161 of these genes inhibited cell growth significantly more in the ER-negative compared to ER-positive cells by at least 1 of the 4 siRNAs, 27 genes showed similar effect with 2 or more siRNAs and for 2 genes 3 of the 4 siRNAs showed preferential growth inhibition in ER-negative cells. These two genes were VLDLR (very low-density lipoprotein receptor) and LRP8 (low density lipoprotein receptor-related protein 8). We validated the siRNA screen results and confirmed down regulation of the mRNA and protein levels for VLDLR and LRP8 in 4 different ER-negative cell lines and showed that siRNA inhibition can be rescued by co-transfection of the receptor genes. Reanalysis of gene expression data also indicated expression of the LRP8 and VLDLR ligands, Reelin or ApoE, in both breast cancer tissues and in cell lines. We next demonstrated that exposure to Reelin and ApoE stimulates the growth of ER-negative cells in vitro. The stimulatory effect of ApoE was isoform dependent ApoE2 (Cys112/Cys158;) has the lowest receptor binding affinity and showed no growth stimulation, ApoE3 (Cys112/ Arg158) had modest 50–60% growth stimulation and ApoE4 (Arg112/ Arg158) had the greatest stimulatory effect (300-400%). Suppression of the expression of either LRP8 or VLDLR or exposure to RAP (an inhibitor of ligand binding to LRP8 and VLDLR) abolished this ligand-induced proliferation. ApoE4 stimulation results in the transcriptional upregulation of genes involved in proliferation, metabolism, and inflammatory signaling pathways. ApoE4 stimulation increases expression of proteins involved in MAPK/ERK pathway, DNA damage repair, and inflammation.

Conclusions: We show that theApoE - LRP8/VLDLR ligand receptor system is overexpressed in human TNBC. We also demonstrated that this receptor system mediates a strong growth promoting and survival function in TNBC cells in vitro. Interestingly, allelic imbalance favoring ApoE4 expression (E3/E4 or E4/E4) has been linked to higher risk of developing early onset breast cancer, which is primarily TNBC. We propose that inhibitors of LRP8/VLDLR signaling may be clinically useful therapeutic or preventive agents for TNBC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-17-01.

S6-4: Protein Kinase Mutation Patterns in Human Breast Cancer

Background: We performed next generation targeted sequencing of all known human protein kinases (n=530 genes) and 56 additional cancer related genes (BRCA1,2, p53, PTEN, etc..) in 112 samples to assess the kinase mutation landscape of breast cancer. Gene expression profiling was also performed on RNA from each specimen and DNA copy number variations were assessed in a subset of 59 cases using array CGH. The three types of genomic data were mapped to canonical biological pathways to identify frequently genomically disturbed pathways in these cancers.

Methods: DNA and RNA extracted from fine needle biopsies of 92 breast cancers were analyzed, 20 samples were sequenced in duplicates or triplicates to assess technical variation of the results. Targeted sequencing was performed with Agilent SureSelect Human Kinome kit and the SOLiD sequencing platform. Gene expression profiling and array CGH were performed with Affymetrix U133A chips and Agilent 244K CGH array. Sequence data was mapped to hg19, functional impact scores were calculated with SWIFT, canonical pathways were obtained from the Broad Institute.

Results: 0.1% of the entire genome was sequenced and &gt;80% of target base pairs had &gt; 20-fold coverage. The mean number of single nucleic acid variants (SNV) and indels per sample were 1043 (range: 493–1583, about 60% homozygous) and 159 (range: 75–269) respectively, 97% of SNVs and 78% of indels were already represented in dbSNP or COSMIC data bases. About 20% of SNVs were predicted to alter kinase or other biological function. The mean number of functionally high impact SNVs was 28 per sample (range 11–47). In addition to known p53 and PI3K mutations we detected frequent mutations in BRCA1 (20%) and observed several predicted high impact SNVs in HER2 (20%) as well as in many MAPK family enzymes. Not all SNVs were distributed equally across disease subsets, SNVs in ULK4, BMP2K, PALB2, ALPK3 were more frequent in triple negative cancers (TNBC) whereas SNVs in EPHA2 was more common in ER+ cancers. Among TNBC, those with residual cancer after neo-adjuvant chemotherapy (n=22) had significantly higher rates of SNVs in HUNK, TRPM7, NEK1 and HER3 compared to cases with pathologic complete response (n=25). When high impact SNVs, DNA copy number alterations and gene over-expression (relative to normal breast n=45) observed in individual cases were mapped to biological pathways a complex network of anomalies emerged for each case.

Conclusion: We observed several known mutations in cancer genes and also detected many SNVs in important regulatory genes that were previously described as functional, germ-line variants with experimentally validated or suspected impact on protein function. Individual cancers have unique combinations of these events. This suggest that cancers arise in the context of complex genomic “germ line noise” which may determine which types of somatic events can or cannot “drive” individual cancers. The data also suggest therapeutic hypotheses about what biological pathways should be targeted in individuals and in subsets of cancers.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S6-4.

The postpartum cardiovascular risk factor profile of women with isolated hyperglycemia at 1-hour on the oral glucose tolerance test in pregnancy

BACKGROUND AND AIMS

Women with gestational diabetes mellitus (GDM) have an enhanced cardiovascular risk factor profile at 3-months postpartum and an elevated risk of future cardiovascular disease, as compared to their peers. Recently, it has emerged that even mild dysglycemia on antepartum oral glucose tolerance test (OGTT) predicts an increased risk of future cardiovascular disease, although it is not known whether there exists an identifiable high-risk subgroup within this patient population. Since gestational impaired glucose tolerance (GIGT) due to isolated hyperglycemia at 1-h during the OGTT (1-h GIGT) bears metabolic similarity to GDM, we hypothesized that, like GDM, 1-h GIGT may predict a high-risk postpartum cardiovascular phenotype.

METHODS AND RESULTS

In this prospective cohort study, 485 women underwent antepartum OGTT, followed by cardiovascular risk factor assessment at 3-months postpartum. The antepartum OGTT identified 4 gestational glucose tolerance groups: GDM (n = 137); 1-h GIGT (n = 39); GIGT at 2- or 3-h (2/3-h GIGT)(n = 50); and normal glucose tolerance (NGT)(n = 259). After adjustment for age, ethnicity, breastfeeding and waist circumference, mean levels of the following cardiovascular risk factors progressively increased from NGT to 2/3-h GIGT to 1-h GIGT to GDM: LDL cholesterol (p = 0.0026); total cholesterol:HDL (p = 0.0030); apolipoprotein B (p = 0.004); apolipoprotein B:apolipoprotein A1 (p = 0.026); leptin (p = 0.018); and C-reactive protein (p = 0.011).

CONCLUSIONS

Amongst women without GDM, 1-h GIGT predicts an enhanced postpartum cardiovascular risk factor profile. It thus emerges, that amongst young women with mild dysglycemia in pregnancy, those with 1-h GIGT may comprise an unrecognized patient population at risk for future cardiovascular disease.

Synthesis of low-melting-point metallic nanoparticles with an ultrasonic nanoemulsion method

A one-step, economical nanoemulsion method has been introduced to synthesize low-melting-point metallic nanoparticles. This nanoemulsion technique exploits the extremely high shear rates generated by the ultrasonic agitation and the relatively large viscosity of the continuous phase - polyalphaolefin (PAO), to rupture the molten metal down to diameter below 100 nm. Field's metal nanoparticles and Indium nanoparticles of respective average diameters of 15 nm and 30 nm have been obtained. The nanoparticles size and shape are determined by transmission electron microscopy (TEM). Their phase transition behavior is examined using a differential scanning calorimeter (DSC). It is found that these nanoparticles dispersed in PAO can undergo reversible, melting-freezing phase transition, and exhibit a relatively large hysteresis. The experimental results suggest that the nanoemulsion method is a viable route for mass production of low-melting nanoparticles.

Phosphorus removal using nanofiltration membranes

A high concentration of phosphorus in wastewater may lead to excessive algae growth and deoxygenation of the water. In this work, nanofiltration (NF) of phosphorus-rich solutions is studied in order to investigate its potential in removing and recycling phosphorus. Wastewater samples from a pulp and paper plant were first analyzed. Commercial membranes (DK5, MPF34, NF90, NF270, NF200) were characterized and tested in permeability and phosphorus removal experiments. NF90 membranes offer the highest rejection of phosphorus; a rejection of more than 70% phosphorus was achieved for a feed containing 2.5 g/L of phosphorus at a pH <2. Additionally, NF90, NF200 and NF270 membranes show higher permeability than DK5 and MPF34 membranes. The separation performance of NF90 is slightly affected by phosphorus concentration and pressure, which may be due to concentration polarization and fouling. By adjusting the pH to 2 or adding sulfuric acid, the separation performance of NF90 was improved in removing phosphorus. However, the presence of acetic acid significantly impairs the rejection of phosphorus.

Overexpression of α-2,6 sialyltransferase stimulates propagation of human influenza viruses in Vero cells

Human influenza viruses are major concern as the leading cause of global pandemics. In infecting cells, they preferentially bind to sialyloligosaccharides containing terminal N-acetyl sialic acid linked to galactose by an α-2,6-linkage (NeuAcα2,6Gal). The amount of NeuAcα2,6Gal in Vero cells, which are predominantly used for production of influenza vaccines over the past 30 years, may not be as high as that in epithelial cells of human respiratory tract, what leads to the suboptimal virus growth in Vero cells. In this study, we stably transfected Vero cells with cDNA of human α-2,6-sialyltransferase (SIAT1), an enzyme catalyzing α-2,6-sialylation of galactose on glycoproteins. Overexpression of SIAT1 in the transfected Vero cells (Vero-SIAT1 cells) was confirmed by Western blot analysis and immunofluorescence microscopy. Vero-SIAT1 cells expressed 7 times higher amounts of NeuAcα2,6Gal, but 3 times lower amounts of NeuAcα2,3Gal as compared to parental Vero cells. Furthermore, the influenza viruses A (H1N1 and H3N2) and B grew in Vero-SIAT1 cells to the higher titers than in Vero cells. Taken together, these results imply that Vero-SIAT1 cells are useful not only for the propagation of human influenza viruses, but also for the preparation of influenza vaccines.

Abstract P2-09-39: Multi-Gene Predictors Developed from Breast Cancer Cell Lines To Predict Response to Chemotherapy: A Validation Study on US Oncology Study 02-103

PURPOSE: Multi-gene predictors (MGPs) of response to multidrug chemotherapy regimens were developed using an in vitro chemoresponse assay in which cell lines were exposed to chemotherapy. The goal of this study was to assess the predictive value of these MGPs using clinical breast cancer patient gene expression data from a clinical trial. METHOD: US Oncology 02-103 was a phase II trial in which women with stage II/III breast cancer were treated with neoadjuvant chemotherapy consisting of four cycles of fluorouracil/epirubicin/cyclophosphamide (FEC) followed by four cycles of docetaxel/capecitabine (TX). Most HER-2 positive patients also received trastuzumab. MGPs of FEC, TX and TFEC (docetaxel/fluorouracil/epirubicin/cyclophosphamide) sensitivity were developed using in vitro assay results from breast cancer cell lines exposed to these drug combinations and publicly-available gene expression data for the same cell lines. MGPs were not developed for trastuzumab treatment. Area under the receiver-operator curve (AUC) was used to evaluate the performance of the three MGPs’ to predict patient pathologic complete response (pCR). Patients who did or did not receive trastuzumab were evaluated separately. Validation was performed blindly and the predictors were applied without knowledge of patient clinical outcome. RESULTS: Eighty-six patients had genomic data available and were included in this analysis. The predictive performance of the FEC, TX and TFEC MGPs were AUCs of 0.72, 0.69, and 0.73, respectively, in the patients who received FEC-TX chemotherapy without trastuzumab (n=61). Within this group, higher AUCs were observed in ER-negative patients compared to ER-positive patients (0.69, 0.72, 0.74 vs. 0.64, 0.54, 0.62, respectively). The prediction accuracies were low (AUCs = 0.43, 0.56 and 0.43) for patients who received trastuzumab together with chemotherapy (n=25) as expected, indicating that the MGPs may have the potential to be regimen-specific.

CONCLUSION: Cell line-derived MGPs of multidrug chemotherapy regimens showed promising performance in this blinded validation study, particularly among patients with ER-negative breast cancers. Further clinical data are needed to confirm this finding.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-39.

Abstract P6-14-06: Prospective Testing of Three Different Gene-Signatures for Patient Selection for Dasatinib Therapy in Metastatic Breast Cancer

Background: Several gene signature-based predictors of response to targeted drugs have been proposed in the literature but none has been prospectively tested as patient selection tools in the clinic. The goal of this trial is to assess the positive predictive value of 3 conceptually different multi-gene signatures as predictors of response to the multitargeted kinase inhibitor dasatinib.

Methods: This clinical trial requires biopsy of a metastatic lesion for gene expression profiling and employs a parallel, multi-arm, two-step, phase II design. Three markers are assessed including a (i) cell-line derived dasatinib-sensitivity signature, (ii) a src-pathway activity signature and (iii) a dasatinib target index calculated as the weighted average expression of all known dasatinib targets. Only markerpositive patients are treated with dasatinib 100 mg po daily and each marker arm is considered as a separate study with early stopping rules for futility (minimum sample size 9, maximum sample size 40/marker arm). A predictor is considered worthy of further study if the clinical benefit rate (i.e. positive predictive value) is ≥25%.

Results: Forty seven patients were accrued from July 2009 through June, 2010, 49 biopsies were performed (soft tissues n=31, liver n=8, bone n=3, lung n=1, adrenal gland n=1), 6 samples had poor cellularity and 3 failed array QC. There was no patient recall, hospitalization or emergency room visit due to biopsy procedure. The median time from biopsy to genomic prediction result was 5 days (range 3-7). Twenty three (57%) patients had positive result for at least 1 predictor (5 were positive for 2) and 20 are receiving therapy (3 withdraw or progressed before therapy began). Responses as of June 2010; Target index arm (n=9): 5 PD (progressive disease), 4 SD (3 stable disease at 8 weeks 1 SD at 16 weeks); SRC Pathway arm (n=5): 3 PD, 2 SD at 8 weeks; Cell line predictor arm (n=6): 2 PD, 1 SD at 8 weeks, 3 not yet reached response evaluation. None of the 3 predictive marker arms have met early stopping yet and accrual is ongoing. Conclusion: Gene-expression signature based patient selection for targeted therapy is feasible and FNA biopsies of metastatic lesions for genomic testing are safe. Updated efficacy results will be reported.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-14-06.

Electron standing waves on the GaN(0001)-pseudo (1 × 1) surface: a FT-STM study at room temperature

We report the direct imaging of standing waves on a GaN(0001)-pseudo (1 × 1) metallic surface, which consists of two atomic Ga layers with the top layer incommensurate. Two types of periodic oscillation are observed by scanning tunneling microscopy at room temperature. The longer wavelength standing waves are due to electron scattering by dislocation-induced steps and two-dimensional InN islands. The localized shorter wavelength waves are attributed to a structural transition of the incommensurate Ga bilayer to a tetrahedral Ga bilayer after the growth of the InN islands.

Initial short-term intensive insulin therapy as a strategy for evaluating the preservation of beta-cell function with oral antidiabetic medications: a pilot study with sitagliptin

AIM

Studies evaluating the effects of oral antidiabetic drugs (OADs) on beta-cell function in type 2 diabetes mellitus (T2DM) are confounded by an inability to establish the actual baseline degree of beta-cell dysfunction, independent of the deleterious effects of hyperglycaemia (glucotoxicity). Because intensive insulin therapy (IIT) can induce normoglycaemia, we reasoned that short-term IIT could enable evaluation of the beta-cell protective capacity of OADs, free from confounding hyperglycaemia. We applied this strategy to assess the effect of sitagliptin on beta-cell function.

METHODS

In this pilot study, 37 patients with T2DM of 6.0 + 6.4 years duration and A1c 7.0 + 0.8% on 0-2 OADs were switched to 4-8 weeks of IIT consisting of basal detemir and premeal insulin aspart. Subjects achieving fasting glucose <7.0 mmol/l 1 day after completing IIT (n = 21) were then randomized to metformin with either sitagliptin (n = 10) or placebo (n = 11). Subjects were followed for 48 weeks, with serial assessment of beta-cell function [ratio of AUC(Cpep) to AUC(gluc) over Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) (AUC(Cpep/gluc) /HOMA-IR)] on 4-h meal tests.

RESULTS

During the study, fasting glucagon-like-peptide-1 was higher (p = 0.003) and A1c lower in the sitagliptin arm (p = 0.016). Nevertheless, although beta-cell function improved during the IIT phase, it declined similarly in both arms over time (p = 0.61). By study end, AUC(Cpep/gluc) /HOMA-IR was not significantly different between the placebo and sitagliptin arms (median 71.2 vs 80.4; p = 0.36).

CONCLUSIONS

Pretreatment IIT can provide a useful strategy for evaluating the beta-cell protective capacity of diabetes interventions. In this pilot study, improved A1c with sitagliptin could not be attributed to a significant effect on preservation of beta-cell function.

Carbon monoxide releasing molecule-3 inhibits concurrent tumor necrosis factor-α- and interleukin-1β-induced expression of adhesion molecules on human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Carbon monoxide releasing molecule-3 (CORM-3) is a newly reported compound that has shown anti-inflammatory effects in a number of cells. In this study, we aimed to investigate the influence of CORM-3 on concurrent tumor necrosis factor-α (TNF-α)- and interleukin (IL)-1β-induced expression of adhesion molecules on human gingival fibroblasts (HGF).

MATERIAL AND METHODS

HGF were cultured from the explants of normal gingival tissues. Cells were costimulated with TNF-α and IL-1β in the presence or absence of CORM-3 for different periods of time. The expression of adhesion molecules, nuclear factor-kappaB (NF-κB) and phosphorylated p38 was studied using western blotting. RT-PCR was applied to check the expression of the adhesion molecules at the mRNA level. The activity of NF-κB was analysed using a reporter gene assay.

RESULTS

CORM-3 inhibited the up-regulation of intercellular adhesion molecule 1, vascular cell adhesion molecule 1 and endothelial leukocyte adhesion molecule in HGF after costimulation with TNF-α and IL-1β, which resulted in the decreased adhesion of peripheral blood mononuclear cells to these cells. Sustained activation of the NF-κB pathway by costimulation with TNF-α and IL-1β was suppressed by CORM-3, which was reflected by a reduced NF-κB response element-dependent luciferase activity and decreased nuclear NF-κB-p65 expression. CORM-3 inhibited MAPK p38 phosphorylation in response to stimulation with proinflammatory cytokines.

CONCLUSION

The results of this study bode well for the application of CORM-3 as an anti-inflammatory agent to inhibit NF-κB activity and to suppress the expression of adhesion molecules on HGF, which suggests a promising potential for CORM-3 in the treatment of inflammatory periodontal disease.

Epitaxial graphene on SiC(0001): more than just honeycombs

Using scanning tunneling microscopy with Fe-coated W tips and first-principles calculations, we show that the interface of epitaxial graphene/SiC(0001) is a warped graphene layer with hexagon-pentagon-heptagon (H(5,6,7)) defects that break the honeycomb symmetry, thereby inducing a gap and states below E(F near the K point. Although the next graphene layer assumes the perfect honeycomb lattice, its interaction with the warped layer modifies )the dispersion about the Dirac point. These results explain recent angle-resolved photoemission and carbon core-level shift data and solve the long-standing problem of the interfacial structure of epitaxial graphene on SiC(0001).

Meta-based association of the lipoprotein lipase gene S447X variant with hypertension and blood pressure variation

Association of the lipoprotein lipase (LPL) gene S447X variant with hypertension has been investigated extensively, whereas the results are often irreproducible. We therefore conducted a meta-analysis to examine whether S447X variant was associated with hypertension and blood pressure variation. Case-control reports published in English language and humans were identified from MEDLINE, EMBASE and Web of Science search engines as of 10 December 2009. Fixed-effects model was applied to pool data in the absence of between-studies heterogeneity, and random-effects model otherwise. A total of five studies (960 cases and 1145 controls) for hypertension and four studies (n=2777) for blood pressure were included. Compared with 447SS homogeneous carriers, those with 447X variant had a lower risk of hypertension (odds ratio (OR)=0.78; 95% confidence interval (CI): 0.62-0.98; P=0.03), and this effect reached significance under the fixed-effects model (I(2)=30% and P=0.22). Similarly, compared with 447S allele carriers, those with 447X allele carriers also had a lower risk of hypertension (OR=0.79; 95% CI: 0.64-0.98; P=0.03). In case of pregnancy-induced hypertension, no significance was observed (P>0.05). As for blood pressure association, there was no significant difference between 447X variant and 447SS homogeneous carriers for both systolic and diastolic blood pressure in the whole population, even stratified by gender (P>0.05). The Egger test told no publication bias for all associations. This meta-analysis demonstrated that LPL gene S447X variant was significantly associated with hypertension and showed no obvious relation with pregnancy-induced hypertension and blood pressure variation.

Increased lipolysis in adipose tissues is associated with elevation of systemic free fatty acids and insulin resistance in perilipin null mice

Elevated plasma levels of free fatty acids (FFAs) are thought to restrict glucose utilization and induce insulin resistance. Plasma FFA concentrations are primarily governed by lipolysis in adipocytes. Perilipin surrounds the lipid droplet in adipocytes and has a dual role in lipolysis regulation. Perilipin null mice studied by two independent laboratories exhibited similar phenotypes of reduced adipose mass and resistance to diet-induced obesity, but have inconsistent metabolic parameters such as plasma levels of FFA, glucose, and insulin. This discrepancy may be due to differences in genetic background, generation, and nutritional status of the animals examined. In this study, we examined the major metabolic parameters in 129/SvEv perilipin null mice fasted for 4 h and observed increased plasma concentrations of FFA, glycerol, glucose, and insulin. An increase in the score for the homeostasis model assessment of insulin resistance index confirmed the insulin resistance in perilipin null mice, which may be attributed to the plasma FFA elevation. Basal lipolysis was increased in adipose tissues or primary adipocytes isolated from perilipin null mice with increased mass and activity of hormone-sensitive lipase and adipose triglyceride lipase. The increased lipolytic action may accelerate FFA efflux from the adipose tissues to the bloodstream, thereby accounting for systemic FFA elevation and, hence, insulin resistance in perilipin null mice.

Low adiponectin concentration during pregnancy predicts postpartum insulin resistance, beta cell dysfunction and fasting glycaemia

AIMS/HYPOTHESIS

The postpartum phase following gestational diabetes (GDM) is characterised by subtle metabolic defects, including the beta cell dysfunction that is believed to mediate the increased future risk of type 2 diabetes in this patient population. Low circulating levels of adiponectin and increased leptin and C-reactive protein (CRP) have recently emerged as novel diabetic risk factors, although their relevance to GDM and subsequent diabetes has not been characterised. Thus, we sought to determine whether adiponectin, leptin and CRP levels during pregnancy relate to the postpartum metabolic defects linking GDM with type 2 diabetes.

METHODS

Metabolic characterisation, including oral glucose tolerance testing, was undertaken in 487 women during pregnancy and at 3 months postpartum. Based on the antepartum OGTT, there were 137 women with GDM, 91 with gestational impaired glucose tolerance and 259 with normal glucose tolerance.

RESULTS

Adiponectin levels were lowest (p < 0.0001) and CRP levels highest (p = 0.0008) in women with GDM. Leptin did not differ between the glucose tolerance groups (p = 0.4483). Adiponectin (r = 0.41, p < 0.0001), leptin (r = -0.36, p < 0.0001) and CRP (r = -0.30, p < 0.0001) during pregnancy were all associated with postpartum insulin sensitivity (determined using the insulin sensitivity index of Matsuda and DeFronzo [IS(OGTT)]). Intriguingly, adiponectin levels were also related to postpartum beta cell function (insulinogenic index/HOMA of insulin resistance; r = 0.16, p = 0.0009). Indeed, on multiple linear regression analyses, adiponectin levels during pregnancy independently predicted both postpartum insulin sensitivity (t = 3.97, p < 0.0001) and beta cell function (t = 2.37, p = 0.0181), even after adjustment for GDM. Furthermore, adiponectin emerged as a significant negative independent determinant of postpartum fasting glucose (t = -3.01, p = 0.0027).

CONCLUSIONS/INTERPRETATION

Hypoadiponectinaemia during pregnancy predicts postpartum insulin resistance, beta cell dysfunction and fasting glycaemia, and hence may be relevant to the pathophysiology relating GDM with type 2 diabetes.

Epigenetic inactivation of the miR-34a in hematological malignancies

miR-34a is a transcriptional target of p53 and implicated in carcinogenesis. We studied the role of miR-34a methylation in a panel of hematological malignancies including acute leukemia [acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL)], chronic leukemia [chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML)], multiple myeloma (MM) and non-Hodgkin's lymphoma (NHL). The methylation status of miR-34a promoter was studied in 12 cell lines and 188 diagnostic samples by methylation-specific polymerase chain reaction. miR-34a promoter was unmethylated in normal controls but methylated in 75% lymphoma and 37% myeloma cell lines. Hypomethylating treatment led to re-expression of pri-miR-34a transcript in lymphoma cells with homozygous miR-34a methylation. In primary samples at diagnosis, miR-34a methylation was detected in 4% CLL, 5.5% MM samples and 18.8% of NHL at diagnosis but none of ALL, AML and CML (P = 0.011). In MM patients with paired samples, miR-34a methylation status remained unchanged at progression. Amongst lymphoid malignancies, miR-34a was preferentially methylated in NHL (P = 0.018), in particular natural killer (NK)/T-cell lymphoma. In conclusion, amongst hematological malignancies, miR-34a methylation is preferentially hypermethylated in NHL, in particular NK/T-cell lymphoma, in a tumor-specific manner, therefore the role of miR-34a in lymphomagenesis warrants further study.

The response to short-term intensive insulin therapy in type 2 diabetes

AIM

Although a short course of intensive insulin therapy (IIT) can improve beta-cell function and glycaemic control in most patients with newly diagnosed type 2 diabetes (T2DM), the impact of this intervention in diabetes of longer duration has not been carefully studied. Thus, we sought to evaluate the effect of short-term IIT in patients with established T2DM.

METHODS

Thirty-four patients, with diabetes of mean 5.9 +/- 6.6 years duration, underwent 4-8 weeks of IIT, with 4-h meal test administered at baseline and at 1 day post-IIT. A positive clinical response was defined as fasting glucose < 7.0 mmol/l off any antidiabetic therapy at the latter test.

RESULTS

A positive response was achieved in 68% (n = 23) of the subjects. At baseline meal test, the responders had lower glucose levels than the non-responders from 120 to 240 min (all timepoints p < or = 0.0008) and higher late incremental area-under-the-C-peptide-curve (AUC(Cpep)), particularly from 60 to 150 min (all p < 0.005). Beta-cell function (ratio of AUC(Cpep) to AUC(gluc) divided by HOMA-IR) was similar between the groups at baseline (median 54.1 vs. 51.3, p = 0.62) but after IIT was significantly higher in the responders (109.3 vs. 57.4, p = 0.009). At baseline, the strongest predictors of the change in beta-cell function were glucose levels between 180 and 240 min (all r = -0.5, p = 0.005) and incremental AUC(Cpep) from 120 to 180 min (all r > or = 0.66, p < or = 0.0001), both reflecting late-phase insulin secretion.

CONCLUSIONS

The clinical response to short-term IIT is variable, consistent with the heterogeneity of T2DM. However, preserved late-phase insulin secretion may identify those patients who can benefit from this intervention with improved beta-cell function.

Effects of physicochemical factors on Cr(VI) removal from leachate by zero-valent iron and alpha-Fe(2)O(3) nanoparticles

The effects of nanoparticle dosage, initial hexavalent chromium concentration, pH value, reaction temperature, and initial concentration of humic acid (HA) on chromate (CrO(4)(2-)) removal from landfill leachate by nanoscale zero-valent iron (NZVI) and hematite (alpha-Fe(2)O(3)) nanoparticles were examined in the present investigations. The Cr(VI) removal rate decreased as the initial Cr(VI) concentration and the reaction temperature increased, whereas corresponding removal rate by NZVI was higher than that of alpha-Fe(2)O(3). The optimum pH for the removal of Cr(VI) by NZVI was found to be 5.0 and more than 99.0% of Cr(VI) was removed within 5 h. However, the removal rate by alpha-Fe(2)O(3) decreased as pH increased. Presence of HA resulted in substantial reduction in the rate and extent of Cr(VI) removal by NZVI, whereas Cr(VI) removal rate by alpha-Fe(2)O(3) did not significantly decrease as HA concentration increased from 0.5 g/L to 3.0 g/L. Increasing the dosage of nanoparticles enhanced the rate constant and the removal of Cr(VI) by NZVI and alpha-Fe(2)O(3) followed pseudo-first-order reaction kinetics. The information should be very useful for the successful application of NZVI and alpha-Fe(2)O(3) for the treatment of groundwater or raw wastewater.

The Molecular Anatomy of Breast Cancer Stroma; Independent Prognostic Role in ER-Positive and ER-Negative Cancers

BackgroundIn this paper we examine the various molecular components of a breast cancer stromal gene signature and correlate these with clinical phenotype and outcome including prognosis and response to preoperative chemotherapy.MethodsWe compared Affymetrix HGU133A-based gene expression profiles of 37 matching core needle biopsies (CNB) and fine-needle aspirations (FNA) from the same cancers. Genes over-expressed in CNB relative to the FNA were defined as the “stromal signature”. Gene expression data from 56 breast cancer cell lines, two separate neoadjuvant data sets (n=233, n=103), 3 independent cohorts of node negative, untreated patients (n=286, n=198, n=200) and 259 estrogen receptor-positive (ER+) tamoxifen-treated patients were used to assess the prognostic and predictive values of these genes in ER+ and ER- cancers separately. Univariate and multivariate Cox analyses were performed. Metagenes were defined as average expression of co-clustered genes.Results293 probe sets (206 genes) were significantly over-expressed in the CNBs (false discovery rate ≤ 0.001, fold-change ≥ 3). These genes overlapped with previously reported stromal signatures and fell into several co-expression clusters including a B-cell/Plasma Cell (B-cell), Dendritic cell, extracellular matrix (ECM), and TGFb-receptor metagenes. Interestingly, ER+ and ER- cancers showed a significantly different stroma-gene expression pattern, and many stromal genes were also differentially expressed between ER+ and ER- breast cancer cell lines. The ECM and TGFb metagenes had modest and variable prognostic value across different datasets in both ER groups. The Dendritic and B cell metagenes were highly co-expressed, but the B-cell metagene had more robust and consistent prognostic value. The B-cell metagene was statistically significant prognostic in univariate and multivariate analysis in ER+/High proliferative and ER- tumors, but it was not prognostic in ER+/Low proliferative tumors. In the 3 different node negative, untreated patient cohorts, the ER+/High proliferative cancers in the lowest B-cell metagene tertile had 10-year distant metastasis free survival (DMFS) of 0.18 (0.07-0.46), 0.22 (0.06-0.75), and 0.44 (0.21-0.92) compared to 0.71 (0.54-0.94), 0.89 (0.71-1.00) and 0.89 (0.71-1.00) in the highest tertile. Among the ER- cancers, the lowest B cell metagene group had 10-year DMFS of 0.57 (0.44-0.75), 0.63 (0.48-0.83), and 0.44 (0.25-0.76) compared to 0.93 (0.81-1.00), 0.83 (0.64-1.00) and 0.83 (0.58-1.00) in the highest B-cell metagene group in each prognostic dataset, respectively. The B-cell metagene was also prognostic in univariate (HR 0.83 (0.71-0.98) p=0.03) and multivariate (HR 0.80 (0.68-0.94) p=0.007) analysis in the Tamoxifen-treated cohort. None of the above stromal metagenes showed reproducible association with response to chemotherapy.ConclusionsThe B-cell/Plasma cell metagene component of the “stroma-related genes” is a robust and reproducible prognostic marker in ER+/High proliferative and also in ER- cancers. Other stromal genes are variably expressed in ER+ and ER- tumors and many are also expressed by neoplastic cells in culture and by primary tumors and carry less reproducible prognostic value.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 105.

Evaluation of the Predictive Performance and Regimen Specificity of a 30-Gene Predictor of Pathologic Complete Response in a Prospective Randomized Neoadjuvant Clinical Trial for Stage I-III Breast Cancer

Purpose: To prospectively evaluate in a randomized trial if a previously reported multigene predictor of pathologic complete response (pCR) to preoperative weekly paclitaxel and fluorouracil-doxorubicin-cyclophosphamide (T/FAC) chemotherapy can accurately predict pCR to neoadjuvant T/FAC chemotherapy, and if it also predicts pCR to FAC only chemotherapy. Furthermore, it is unknown if the T/FAC regimen is superior to 6 courses of FAC; therefore we compare the pCR rates for patients who receive T/FAC versus FACx6 preoperative chemotherapy.Materials and Methods: Patients with stage I-III breast cancer (n=273) were randomly assigned to receive either 12 courses of weekly paclitaxel followed by 4 courses of FAC (T/FAC, n=138), or 6 courses of FAC (FACx6, n=135) neoadjuvant chemotherapy. All patients underwent a pretreatment FNA biopsy of the tumor for gene expression profiling on oligonucleotide microarrays, and treatment response prediction (pCR versus residual disease, RD) was performed using the multigene predictor. Predicted and observed pathologic responses were compared independently in the two treatment arms.Results: The pCR rate was 19% with T/FAC and 9% with FACx6 (p&lt;0.05). In the T/FAC arm, the positive predictive value (PPV) of the genomic predictor was 38% (95%CI:21-56%), the negative predictive value (NPV) 88% (CI:77-95%), sensitivity 63% (CI:38-84%), specificity 72% (CI:60-82%), and the AUC 0.711. In the FAC only treatment arm, the PPV was 9% (CI:1-29%), the NPV 92% (CI:83-97%), sensitivity 29% (CI:4-71%), specificity 75% (CI:64-84%), and the AUC 0.584. This suggests that the genomic predictor is regimen-specific. In a multivariate analysis including age, tumor size, nodal status, histologic grade, HER2 and estrogen receptor (ER) status and the genomic predictor, only ER status was a significant predictor of pCR.Discussion: Pathologic complete response rate was significantly higher in the T/FAC arm compared to the FACx6 arm indicating a higher efficacy of the paclitaxel containing arm. Patients who were predicted to achieve pCR to T/FAC had a significantly higher pCR rate (38%) than unselected patients (19%) or patients predicted to have RD (12%) when treated with this regimen. These results confirm that the multigene predictor can identify patients with greater than average sensitivity to T/FAC chemotherapy.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 101.

Clinical Subtype-Derived p53 Gene Signature Is Predictive of Prognosis and Response to Chemotherapy in ER-Positive but Not in ER-Negative Breast Cancers

BackgroundBreast cancer is a collection of molecularly distinct neoplastic diseases and therefore, we hypothesized that p53 gene mutations may lead to different transcriptional changes in the different molecular subtypes and these may translate into subtype-dependent prognostic and predictive values.MethodsWe developed gene expression-based predictors of p53 status separately for estrogen receptor-positive (ER+) and -negative (ER-) breast cancers from a publicly available data set with known p53 mutation status (n=251). We validated the two signatures on an independent cohort of cancers (n=103) with known p53 functional status and tested their prognostic and predictive values on two other cohorts of breast cancers that received no systemic adjuvant therapy (n=255; n=198), and on one cohort of ER+ patients treated with adjuvant tamoxifen (n=277). We also examined if the p53 signatures were associated with chemotherapy sensitivity in ER+ and ER- cancers, respectively in two separate neoadjuvant data sets (n=233; n=103).ResultsWe developed a 39-gene p53 signature derived from 213 ER+ and a 30-gene p53 signature derived from 38 ER- breast cancers with no overlapping genes. External validation showed a sensitivity and specificity of 89% and 54%, respectively for the 39-gene signature in ER+ breast cancers; and 82% and 61%, respectively for the 30-gene signature in ER- cancers. The 39-gene signature was predictive of worse distant metastasis free survival (DMFS) in ER+ cancers with p53 dysfunction in both prognostic data sets (Hazard ratio (HR): 2.3 (95% confidence interval (CI):1.25-4.23, p=0.005 and HR:2.17 (95%CI:0.85-5.56, p=0.09). It remained predictive of worse DMFS even after tamoxifen adjuvant therapy (HR=2.43, 95%CI: 1.35-4.38, p&lt;0.0001). In contrast it was associated with higher chemotherapy sensitivity in ER+ cancers. Its predictive accuracy for pathologic complete response was of 68% (95%CI: 64-70%), sensitivity 89% (95%CI: 58-98%), specificity 67% (95%CI: 65-68%), positive predictive value 15% (95%CI: 10-17%), and negative predictive value 99% (95%CI: 96-100%) in ER+ cancers. The prognostic and predictive values remained significant in multivariate analysis. The same 39-gene signature was not prognostic or predictive in ER- cancers. The 30-gene signature derived from ER- tumors had no chemotherapy response predictive value in either ER- or ER+ cancers. The p53 dysfunctional cases showed better survival in the absence of any adjuvant therapy among ER- cancers. It had no prognostic value in ER+ cancers.ConclusionThese observations support the hypothesis that predictive or prognostic biomarkers may be best developed separately for different clinical and molecular subsets of breast cancer. P53 dysfunction is clinically most relevant in ER+ breast cancers.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6122.