TLR-Induced SMPD3 Defects Enhance Inflammatory Response of B Cell and Macrophage in the Pathogenesis of SLE

B lymphocyte and macrophages may contribute to SLE pathogenesis through cytokine production after TLR stimulation. Emerging evidences suggested that defects of sphingolipid metabolism were responsible for SLE pathogenesis. However, it is not clear whether these defects exist in B cells and macrophages under SLE condition and whether TLR signalling pathway was related to the dysfunction of sphingolipid metabolism in SLE. Here, we demonstrated that the enzymes involved in the sphingolipid metabolism expressed abnormally in B cells from SLE patients and lupus-prone mice. Moreover, we found that TLR signalling induced the abnormal expression of sphingomyelin phosphodiesterase 3 (SMPD3), sphingosine-1-phosphate phosphatase 2 (SGPP2), ceramide kinase (CERK) and UDP glycosyltransferase 8 (UGT8), which were involved in sphingolipid metabolism. TLR signalling also induced the transportation of SMPD3 from Golgi apparatus. Furthermore, the dysfunction of SMPD3 enhanced TLR-induced inflammatory response of B cells and macrophages in turn. Thus, these findings provide an innovative direction and a new target for research and treatment of SLE.

Performance on a 1-week delayed recall task is associated with medial temporal lobe structures in neurologically normal older adults

OBJECTIVE

Traditional episodic memory tests employ a delayed recall length ranging from 10 to 30 min. The neurobiological process of memory consolidation extends well beyond these time intervals, however, raising the possibility that these tests might not be fully sensitive to the subtle neurocognitive changes found in early disease or age-related decline. We aimed to determine the sensitivity of a 1-week delayed recall paradigm to medial temporal lobe (MTL) structure among neurologically normal older adults.

METHODS

One hundred and forty functionally intact, older adults (mean age = 75.8) completed a story recall test in which participants learned to 90% criterion. Recall was tested after 30-min and 1-week. Participants also completed a standardized list learning task with a 20-min delay (n = 129) and a structural brain MRI. The MTL, including the parahippocampal gyrus, hippocampus, and entorhinal, was our primary region of interest.

RESULTS

Controlling for age, education, gender and total intracranial volume, the standard 20- and 30-min recalls showed no significant relationship with MTL. In contrast, 1-week recall was uniquely associated with MTL structure (partial r = .24, p = .006), specifically entorhinal (partial r = .27; p = .001) and hippocampal (partial r = .21, p = .02) volumes.

CONCLUSION

Memory paradigms that utilize 1-week delays are more sensitive than standard paradigms to MTL volumes in neurologically normal older adults. Longer delay periods may improve detection of memory consolidation abilities associated with age-related, and potentially pathological, neurobehavioral change.

Oral treponeme major surface protein: Sequence diversity and distributions within periodontal niches

Treponema denticola and other species (phylotypes) of oral spirochetes are widely considered to play important etiological roles in periodontitis and other oral infections. The major surface protein (Msp) of T. denticola is directly implicated in several pathological mechanisms. Here, we have analyzed msp sequence diversity across 68 strains of oral phylogroup 1 and 2 treponemes; including reference strains of T. denticola, Treponema putidum, Treponema medium, 'Treponema vincentii', and 'Treponema sinensis'. All encoded Msp proteins contained highly conserved, taxon-specific signal peptides, and shared a predicted 'three-domain' structure. A clone-based strategy employing 'msp-specific' polymerase chain reaction primers was used to analyze msp gene sequence diversity present in subgingival plaque samples collected from a group of individuals with chronic periodontitis (n=10), vs periodontitis-free controls (n=10). We obtained 626 clinical msp gene sequences, which were assigned to 21 distinct 'clinical msp genotypes' (95% sequence identity cut-off). The most frequently detected clinical msp genotype corresponded to T. denticola ATCC 35405^T , but this was not correlated to disease status. UniFrac and libshuff analysis revealed that individuals with periodontitis and periodontitis-free controls harbored significantly different communities of treponeme clinical msp genotypes (P<.001). Patients with periodontitis had higher levels of clinical msp genotype diversity than periodontitis-free controls (Mann-Whitney U-test, P<.05). The relative proportions of 'T. vincentii' clinical msp genotypes were significantly higher in the control group than in the periodontitis group (P=.018). In conclusion, our data clearly show that both healthy and diseased individuals commonly harbor a wide diversity of Treponema clinical msp genotypes within their subgingival niches.

Effect of grape pomace on fermentation quality and aerobic stability of sweet sorghum silage

The objective of this study was to evaluate the effect of grape pomace (GP) with different adding levels (0%, 5%, 10% and 15%, fresh matter basis), alone (GP-LAB) or in combine with an inoculant LAB (GP+LAB), on the fermentation quality and aerobic stability of sweet sorghum silage. After 90 days of ensiling in vacuumized mini-silos, silages were subject to a 7-day aerobic stability test, in which chemical, microbial and polyphenol composition were measured. In the GP-LAB group, adding GP decreased (P < 0.05) concentrations of water-soluble carbohydrate (WSC) and butyric acid in silage. In the GP+LAB group, adding GP increased (P < 0.05) concentrations of lactic acid, WSC and crude protein, decreased (P < 0.05) final pH value, NH₃ -N ratio and butyric acid concentration in silage. Polyphenol level was reduced (P < 0.05) after silage fermentation. During aerobic exposure, the fungi count, pH value and silage temperature increased (P < 0.05), the levels of lactic acid, acetic acid and polyphenols (quercetin 3-O-glucoside and quercetin 3-O-glucuronid) decreased (P < 0.05) in silage. GP+LAB treated silage had a lag phase for aerobic spoilage. When the fermentation products, microbial counts, chemical and polyphenol composition were considered, the use of 10% GP+LAB at ensiling could provide a valuable source for improved fermentation quality and aerobic stability of sweet sorghum silage.

Effects of maturity stage and lactic acid bacteria on the fermentation quality and aerobic stability of Siberian wildrye silage

It is difficult to make good quality of silage from alpine gramineous from the Qinghai Tibetan plateau. The effects of lactic acid bacteria (LAB) on the fermentation quality and aerobic stability of Siberian wildrye silage were studied in southeast of the Qinghai Tibetan plateau. Siberian wildrye materials were freshly cut at the sprouting stage, flowering stage, and milky stage. Silage was prepared by using a small‐scale silage fermentation system (bag silos). Lactobacillus plantarum (LP, 5 × 10⁸ cfu/kg FM), Lactobacillus buchneri (LB, 5 × 10⁸ cfu/kg FM) and their mixture (LP+LB, 5 × 10⁸ cfu/kg FM) as silage additives were separately added to ensiled forages, and no additive served as control (CK). These bag silos were kept at room temperature (<15°C), and the silage qualities were analyzed after 60 days of ensiling. The number of indigenous LAB on fresh materials was less than that of yeasts and molds, and LAB species showed specification adapted to low temperature. LAB inoculated silages had lower (P < 0.05) pH value, NH₃‐N/TN and butyric acid content compared with control silage. Silage treated with LB had higher contents of acetic acid, propionic acid, WSC and CP. However, the aerobic stability of silages inoculated with LAB did not differ significantly between stages (P > 0.05). When fermentation characteristics, chemical composition, and aerobic stability were considered, treatment with L. plantarum resulted in high quality of Siberian wildrye silage harvested at the flowering stage in the alpine region.

Photoacid Behaviour in a Fluorinated Green Fluorescent Protein Chromophore: Ultrafast Formation of Anion and Zwitterion States.†

The photophysics of the chromophore of the green fluorescent protein in Aequorea victoria (avGFP) are dominated by an excited state proton transfer reaction. In contrast the photophysics of the same chromophore in solution are dominated by radiationless decay, and photoacid behaviour is not observed. Here we show that modification of the pKa of the chromophore by fluorination leads to an excited state proton transfer on an extremely fast (50 fs) time scale. Such a fast rate suggests a barrierless proton transfer and the existence of a pre-formed acceptor site in the aqueous solution, which is supported by solvent and deuterium isotope effects. In addition, at lower pH, photochemical formation of the elusive zwitterion of the GFP chromophore is observed by means of an equally fast excited state proton transfer from the cation. The significance of these results for understanding and modifying the properties of fluorescent proteins are discussed.

Developing Fluorogenic Riboswitches for Imaging Metabolite Concentration Dynamics in Bacterial Cells

Genetically encoded small-molecule sensors are important tools for revealing the dynamics of metabolites and other small molecules in live cells over time. We recently developed RNA-based sensors that exhibit fluorescence in proportion to a small-molecule ligand. One class of these RNA-based sensors are termed Spinach riboswitches. These are RNAs that are based on naturally occurring riboswitches, but have been fused to the Spinach aptamer. The resulting RNA is a fluorogenic riboswitch, producing fluorescence upon binding the cognate small-molecule analyte. Here, we describe how to design and optimize these sensors by adjusting critical sequence elements, guided by structural insights from the Spinach aptamer. We provide a stepwise procedure to characterize sensors in vitro and to express sensors in bacteria for live-cell imaging of metabolites. Spinach riboswitch sensors offer a simple method for fluorescence measurement of a wide range of metabolites for which riboswitches exist, including nucleotides and their derivatives, amino acids, cofactors, cations, and anions.

Diamondback Moth (Lepidoptera: Plutellidae) Exhibits Oviposition and Larval Feeding Preferences Among Crops, Wild plants, and Ornamentals as Host Plants

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an agricultural pest with high reproductive potential, widespread distribution, and high resistance to different types of insecticides. Although diamondback moth is a common research subject, questions remain regarding its spatial and temporal host plant usage patterns and preferences within agroecosystems. We examined the adult oviposition and larval feeding preferences of the diamondback moth to assess the potential of alternate host plants as either reservoirs or trap crops. Adult females and third and fourth instars were offered multiple plant species within the plant family Brassicaceae to examine contact preferences and larval ingestion rates. Adult oviposition and larval feeding preferences were identical, with garden cress (Lepidium sativum) (L.) highly preferred, followed by wintercress (Barbarea vulgaris) (L.) and black mustard (Brassica nigra) (L.). Ingestion rates varied among tested plants, with the lowest rate on black mustard and highest on aubretia (Aubretia deltoidea) (L.). Highly preferred plant species were determined to be unfavorable for larval growth and potentially lethal to neonates, suggesting their possible use as trap crops. Understanding ovipositional and larval feeding preferences of diamondback moth can also aid in the development of more accurate monitoring and control strategies for this pest.

Characteristic features of the adenomatoid odontogenic tumour on cone beam CT

OBJECTIVES

To illustrate characteristic features of adenomatoid odontogenic tumour (AOT) on CBCT.

METHODS

The archived CBCT and panoramic radiographs of eight patients histopathologically diagnosed as AOT were analysed. The radiographic features displayed on both radiographic images were carefully described and compared.

RESULTS

All eight AOT cases presented as unilocular and well-demarcated lesions on both CBCT and panoramic images. CBCT images displayed three-dimensional interpretation of AOT lesions, especially the detailed intralesional radiopacities. Numerous discrete radiopaque foci scattered in the lesion with evident contrast to the radiolucent background could be considered as one of the characteristic features of AOT on CBCT.

CONCLUSIONS

Compared with panoramic radiography, CBCT seems to possess better potential in diagnosing AOT.

Molecular insights of genetic variation in Erianthus arundinaceus populations native to China

BACKGROUND

E. arundinaceus (Retz.) Jeswiet is a warm-season, tall-growing perennial species native to much southern portion in China. The grass has been extensively used in sugarcane breeding and is recently targeted as a bioenergy feedstock crop. However, information on the genetic structure of the Chinese wild germplasm is limited. Knowledge of genetic variation within and among populations is essential for breeding new cultivars in the species. The major objective of this study was to quantify the magnitude of genetic variation among and within natural populations in China.

METHODOLOGY/PRINCIPAL FINDINGS

In this experiment, we analyzed genetic variation of 164 individuals of 18 populations collected from natural habitats in six Chinese provinces using 20 sequence-related amplified polymorphism (SRAP) primer pairs generating 277 polymorphic bands. Among and within the populations, the percentage of polymorphic bands (PPB) was 80.00% and 27.07%, genetic diversity (HE ) was 0.245 and 0.099, effective number of alleles (NE ) was 1.350 and 1.170, and Shannon's information index (I) was 0.340 and 0.147, respectively. The populations were clustered into six groups exhibiting a high level of genetic differentiation, which was highly associated with geographic origins of respective germplasm populations, but was not significantly associated with geographic distances between the populations.

CONCLUSIONS/SIGNIFICANCE

This is the first report indicating that large genetic variation exists in the Chinese E. arundinaceus germplasm based on the SRAP molecular marker analysis of native populations. The genetic structure of populations in the species has been substantially affected by geographic landforms and environments. The diverse collection will be highly valuable in genetic improvement in the species per se and likely in sugarcane.

EYA4 is inactivated biallelically at a high frequency in sporadic lung cancer and is associated with familial lung cancer risk

In an effort to identify novel biallelically inactivated tumor suppressor genes (TSG) in sporadic invasive and pre-invasive non-small cell lung cancer (NSCLC) genomes, we applied a comprehensive integrated multi-‘omics approach to investigate patient matched, paired NSCLC tumor and non-malignant parenchymal tissues. By surveying lung tumor genomes for genes concomitantly inactivated within individual tumors by multiple mechanisms, and by the frequency of disruption in tumors across multiple cohorts, we have identified a putative lung cancer TSG, Eyes Absent 4 (EYA4). EYA4 is frequently and concomitantly deleted, hypermethylated and underexpressed in multiple independent lung tumor data sets, in both major NSCLC subtypes, and in the earliest stages of lung cancer. We find not only that decreased EYA4 expression is associated with poor survival in sporadic lung cancers, but EYA4 SNPs are associated with increased familial cancer risk, consistent with EYA4’s proximity to the previously reported lung cancer susceptibility locus on 6q. Functionally, we find that EYA4 displays TSG-like properties with a role in modulating apoptosis and DNA repair. Cross examination of EYA4 expression across multiple tumor types suggests a cell type-specific tumorigenic role for EYA4, consistent with a tumor suppressor function in cancers of epithelial origin. This work shows a clear role for EYA4 as a putative TSG in NSCLC.

Quality of life among advanced breast cancer patients with and without distant metastasis

This study presents the results of a secondary analysis of data collected during a trial of reflexology that aimed to improve health-related quality of life (HRQOL) among women with advanced breast cancer in treatment. A comparison of HRQOL (functioning, symptoms, spirituality) of those with (n = 298) and without (n = 87) distant metastasis is presented. Following the intake interview, 385 women were randomised to reflexology, lay foot manipulation or conventional care control, and were interviewed again at weeks 5 and 11. Those with distant metastasis were older, had fewer comorbid conditions, and a smaller proportion were employed. Longitudinal analysis of HRQOL at intake, 5 and 11 weeks revealed that those with distant metastasis had lower functioning and more pain; however, no differences were found on fatigue, nausea, shortness of breath, sleep quality, anxiety, depressive symptoms or spirituality. Despite advanced disease, 56% of all women in this study were below the clinical screening cut-off for depressive symptoms. These findings may indicate that patients with advanced breast cancer have adapted emotionally and spiritually; however, the management of physical symptoms remains a priority.

Abstract P1-08-02: Gene expression changes in methylnitrosourea (MNU)-induced ER+ mammary cancers following short-term treatment of rats with SERMs (Tamoxifen and Arzoxifene)

SERMs have proven to be highly effective in both therapy and prevention of ER+ breast cancers. Tamoxifen has been the most commonly used SERM, but arzoxifene (another high- affinity competitive SERM agonist) showed strong activity in early clinical trials against ER+ breast cancer; although further development was discontinued. Both SERMs have shown a dose dependent effect on prevention and therapy of rat mammary tumors in the ER+ MNU model of cancer. Of interest, the doses required for prevention was significantly lower than the doses required for therapy. In the present study, rats bearing mammary cancers induced by MNU were treated with tamoxifen (0.66, 3.3, 20 and 100 ppm in diet) or arzoxifene (3.0 ppm in diet) for 5 days. Global gene expression analysis showed that more than 100 genes were down-regulated and more than 100 genes were up-regulated (p &lt; 0.05 and fold change &gt;1.5) in cancers treated with tamoxifen doses &gt; 3 ppm; and that many of these gene changes were dose dependent. The genes modulated by tamoxifen and arzoxifene were enriched in the cell cycle pathway that were related to chromosome condensation in prometaphase [including Aurora-A, Aurora-B, Bub1B, non-SMC condensing I complex, subunit H (BRRN1), Condensin, CAP-G, CAP-G/G2, CAP-H/H2, CAP-D2/D3, CAP-E, TOP2, Cyclin A, Cyclin B, CDK1, Histone H1 and inter-centromere protein (INCENP]. Employing a different set of tamoxifen treated samples, we were able to confirm that many of the same genes were modulated employing a quantitative RT-PCR assay. Finally, we will compare certain of the gene changes obtained in the animal model with gene changes observed in human neoadjuvant trials.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-08-02.

Prevalence and diversity of Synergistetes taxa in periodontal health and disease

BACKGROUND AND OBJECTIVE

Members of the phylum Synergistetes have previously been identified within periodontitis subgingival plaque and are considered putative periodontopathogens. This study compared the diversity of subginigval Synergistetes in a cohort of subjects with periodontitis (n = 10) vs. periodontitis-free controls (n = 10).

MATERIAL AND METHODS

Pooled subgingival plaque samples from all deep periodontal pockets or all sulci were collected from the periodontitis and periodontitis-free subjects, respectively. Bacterial 16S rRNA genes were PCR-amplified from purified subgingival plaque DNA using a Synergistetes 'selective' primer set. PCR products were cloned and sequenced to analyze the prevalence and diversity of Synergistetes operational taxonomic units (OTUs) present in plaque samples of both subject groups.

RESULTS

A total of 1030 non-chimeric 16S rRNA clones were obtained, of which 162 corresponded to members of the phylum Synergistetes. A significantly larger number of Synergistetes clones were obtained from periodontitis subgingival plaque than from periodontitis-free controls (25.4% vs. 5.9%, p < 0.001). All Synergistetes clones corresponded to cluster A oral Synergistetes, and fell into 31 OTUs (99% sequence identity cut-off). Twenty-nine Synergistetes OTUs were detected in the periodontitis group while eight were detected in the periodontitis-free group (p < 0.001). Five Synergistetes OTUs; including one OTU corresponding to the recently-characterized species Fretibacterium fastidiosum, were more prevalent in the periodontitis subjects (p < 0.05).

CONCLUSION

OTUs belonging to oral Synergistetes cluster A were more readily detectable and were more diverse in subgingival plaque from periodontitis subjects compared with periodontitis-free controls. Specific Synergistetes OTUs appear to be associated with periodontitis.

P3-10-02: Gene Expression Changes in Methylnitrosourea (MNU)-Induced ER+ Mammary Cancers Following Short-Term Treatment of Rats with the Aromatase Inhibitor Vorozole

Aromatase inhibitors have proven to be highly effective in both therapy and prevention of ER+ breast cancer. Vorozole (R83842), a high affinity competitive inhibitor of aromatase (similar to letrozole and anastrozole) showed strong activity in early clinical trials against ER+ breast cancer. Furthermore, vorozole was highly effective in the prevention and therapy of ER+ cancers in the MNU-mammary cancer model (Lubet, et al., Carcinogenesis 19, 1345, 1998). In the present study, rats bearing mammary cancers induced by MNU were exposed to vorozole (1.25 mg/kg BW/day) for 5 days. Global gene expression analysis showed that 162 genes were down-regulated and 180 genes up-regulated in cancers treated with vorozole (p &lt; 0.05 and fold change &gt; 1.5). The genes modulated by vorozole were compared with two additional sets of data. First, thirty-two genes and a number of pathways exhibited significantly concordant changes with aromatase inhibitors both in the animal model and in at least three of four published human data sets. In particular, differentially expressed genes enriched in the cell cycle pathway that were related to chromosome condensation in prometaphase [including Aurora-A, Aurora-B, Bub1B, non-SMC condensin I complex, subunit H (BRRN1), Condensin, CAP-G, CAP-G/G2, CAP-H/H2, CAP-D2/D3, CAP-E, TOP2, Cyclin A, Cyclin B, CDK1, Histone H1 and inner centromere protein (INCENP)] were downregulated after treatment with the aromatase inhibitor. These results appear to be in agreement with the strong anti-proliferative effects of aromatase inhibitors in both animal and clinical studies. A second comparison was with an in vitro study in which estrogen was removed from MCF-7 cells in culture. Decreases in genes related to the E2F1 transcription factor were observed. In our study, 13 modulated genes exhibited E2F-1 binding sites in their promoter regions, and 7 genes contained both ER binding and E2F binding sites. We were able to confirm modulation of the cell cycle related and E2F-related genes in a large independent set of human samples treated with anastrozole. The results on RNA changes for Bub 1B, Cyclin A and CDK-1 were verified by employing IHC analysis. In summary, gene changes observed in the rat closely paralleled gene changes associated with aromatase treatment and estrogen withdrawal in humans.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-10-02.

Arginine deprivation, autophagy, apoptosis (AAA) for the treatment of melanoma

The majority of melanoma cells do not express argininosuccinate synthetase (ASS), and hence cannot synthesize arginine from citrulline. Their growth and proliferation depend on exogenous supply of arginine. Arginine degradation using arginine deiminase (ADI) leads to growth inhibition and eventually cell death while normal cell which express ASS can survive. This notion has been translated into clinical trial. Pegylated ADI (ADI-PEG20) has shown antitumor activity in melanoma. However, the sensitivity to ADI is different among ASS(-) melanoma cells. We have investigated and reviewed the signaling pathways which are affected by arginine deprivation and their consequences which lead to cell death. We have found that arginine deprivation inhibits mTOR signaling but leads to activation of MEK and ERK with no changes in BRAF. These changes most likely lead to autophagy, a possible mechanism to survive by recycling intracellular arginine. However apoptosis does occur which can be both caspase dependent or independent In order to increase the therapeutic efficacy of this form of treatment, one should consider adding other agent(s) which can drive the cells toward apoptosis or inhibit the autophagic process.

Ossifying fibromas of the jaw bone: 20 cases

The purpose of this article is to report 20 cases of ossifying fibroma involving the jaw bone and to review the literature of this lesion. All the cases had adequate radiographs and clinical information. Varying shapes of the lesion including cystic lesion and mixed density lesion are presented, including two massive expansile lesions, which measured more than 10 cm.

Genetic variants cis-regulating Xrn2 expression contribute to the risk of spontaneous lung tumor

Gene expression variation is an important mechanism underlying susceptibility to complex disease. In comparison with tobacco-related lung carcinogenesis, lung cancer in nonsmokers may involve important and etiologically distinct causal pathways. In this study, we conducted a genome-wide association study on spontaneous lung tumor incidence in inbred mice and identified a major susceptibility locus on mouse chromosome 2 (rs27328255, P=6.68 x 10(-7)). We then evaluated the correlations of polymorphisms with the transcription of positional candidate genes in normal lungs. Single-nucleotide polymorphism rs27328255 was consistently and strongly associated (P=7.42 x 10(-9)) in cis with transcript levels of Xrn2. We further showed that Xrn2 promotes proliferation and inhibits squamous differentiation in human lung epithelial cells and polymorphisms in human homolog XRN2 are associated with human lung cancer (rs2025811, P=1.90 x 10(-3), OR=1.20). We conclude that genetic variants regulating Xrn2 expression in cis are determinants of spontaneous lung tumor susceptibility in mice and have genetic equivalents in lung cancer susceptibility in human beings. Identifying Xrn2 as a major candidate for spontaneous lung cancer has important implications for the diagnosis and treatment of lung cancer as well as delineation of the mechanisms underlying the genesis of lung cancer in nonsmokers.

A gene expression signature predicts chemopreventive response of an EGFR inhibitor in a rat mammary cancer model

Abstract #1111

Rats treated with the carcinogen methylnitrosourea (MNU) develop multiple, hormonally dependent mammary tumors. The efficacy of the epidermal growth factor receptor (EGFR) inhibitor Gefitinib (Iressa) to prevent MNU-induced mammary cancers in female Sprague-Dawley rats was determined. Rats were given a single dose of MNU (75 mg/kg body weight) at 50 days of age. Rats bearing MNU-induced small palpable cancers showed variable responses to treatment with Iressa; with approximately 50% having a complete regression and the remaining 50% having a partial or no response. We conducted exon array studies of differentially expressed genes and/or alternative splicing exons related to the responses (complete vs partial or no response). Preliminary studies showed that, although there were genes whose expression was similarly modulated in both groups, a gene expression signature can be identified that is highly predictive of which rat mammary tumors are susceptible to treatment with Iressa. Cross validation results indicated that gene expression signatures may be useful in predicting the response of a rat mammary tumor to treatment with Iressa. Currently, we are conducting validation studies in a separate set of rat mammary tumors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1111.

Multi-modality imaging of N-methyl-N-nitrosourea-induced mammary tumors by MRI and small animal PET

Abstract #6008

Background: We evaluated the use of high resolution Magnetic Resonance Imaging (MRI) and small animal Positron Emission Tomography (PET) imaging in assessing tumor proliferation and response to therapy in N-methyl-N-nitrosourea (MNU)-induced mammary tumors.&#x2028; Materials and Methods: The study comprised of 30 untreated MNU rats, 6 Targretin-treated MNU rats, and 6 Vorozole-treated MNU rats. Rats received a baseline imaging session when they developed their first palpable mammary tumor and were subsequently randomized into a control group or a treatment group with either Targretin (220mg/kg in the diet) or Vorozole (1.25mg/kg body weight by gavage). Treatment lasted for 8 weeks following the baseline imaging session. Each rat was imaged for 10-weeks at 2-week intervals with a) FDG to assess the metabolic state of tumors, b) MRI to monitor tumor volume, and c) [18F]ISO-1, a Sigma-2 radiolabeled ligand, to assess the proliferative status of MNU-induced tumors. Static images (10-minute) were obtained 60-minutes post-injection of FDG and [18F]ISO-1. In untreated tumors, a minimum of 40 PET outcome measures were assessed for their ability to predict changes in MRI-derived volume measurements between consecutive imaging sessions. In addition, regression analysis was performed to assess the correlation (R) between the measures. In treated tumors, the time-course of changes in PET outcome measures relative to baseline was evaluated to assess the efficacy of Targretin and Vorozole, in particular in characterizing short-term response (initial 2-weeks) and response to treatment withdrawal (weeks 8-10).&#x2028; Results: An index characterizing a MRI-normalized [18F]ISO-1 uptake significantly correlated (R=0.7, P&lt;0.0003) with changes in tumor volume between consecutive imaging sessions in untreated tumors. In contrast, there was no correlation between FDG outcome measures and changes in tumor volume. Targretin had the strongest short-term efficacy with a reduction in tumor load, on average, by as much as 60% compared with Vorozole's 20% reduction in tumor load. We observed higher rate of tumor resurgence in rats treated with Vorozole compared with Targretin, suggesting a residual effect of Targretin. In general, PET outcome measures of both FDG and [18F]ISO-1 delineated short-term response to treatment and non-responding tumors. [18F]ISO-1 was more sensitive than FDG in capturing tumor growth following treatment withdrawal at week 8.&#x2028; Conclusion: MRI and small animal PET provide a platform to assess MNU-induced tumor proliferation and the efficacy of therapeutic interventions non-invasively, as demonstrated in this work.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6008.