Host evolution shapes gut microbiome composition in Astyanax mexicanus

The ecological and genetic changes that underlie the evolution of host-microbe interactions remain elusive, primarily due to challenges in disentangling the variables that alter microbiome composition. To understand the impact of host habitat, host genetics, and evolutionary history on microbial community structure, we examined gut microbiomes of river- and three cave-adapted morphotypes of the Mexican tetra, Astyanax mexicanus, in their natural environments and under controlled laboratory conditions. Field-collected samples were dominated by very few taxa and showed considerable interindividual variation. We found that lab-reared fish exhibited increased microbiome richness and distinct composition compared to their wild counterparts, underscoring the significant influence of habitat. Most notably, however, we found that morphotypes reared on the same diet throughout life developed distinct microbiomes suggesting that genetic loci resulting from cavefish evolution shape microbiome composition. We observed stable differences in Fusobacteriota abundance between morphotypes and demonstrated that this could be used as a trait for quantitative trait loci mapping to uncover the genetic basis of microbial community structure.

The American Academy of Microbiology discusses gain-of-function research of concern (GOFROC) and enhanced potential pandemic pathogens (ePPP)

The American Academy of Microbiology convened a workshop bringing together scientists with varied opinions on the conduct of gain-of-function research of concern (GOFROC) and enhanced pathogen with pandemic potential (ePPP) research. Five findings were: (1) research on infectious agents is necessary for understanding, monitoring, and developing treatments and prevention measures against these agents; (2) gain-of-function research of concern or ePPP research makes up a very small fraction of all biological research; (3) clearly defined terminologies for research of concern should be developed by the scientific community to avoid public confusion and highlight its practical benefits; (4) harmonized biorisk management standardization, training, mentoring, and reporting can help improve safety and security for laboratory workers and the public; and (5) expanded engagement and collaboration of scientists with policymakers and the public, including increased transparency on the risks and rewards of research with infectious agents, is needed.

Improved scientific knowledge of methanogenesis and methanotrophy needed to slow climate change during the next 30 years

Owing to the high radiative forcing and short atmospheric residence time of methane, abatement of methane emissions offers a crucial opportunity for effective, rapid slowing of climate change. Here, we report on a colloquium jointly sponsored by the American Society for Microbiology and the American Geophysical Union, where 35 national and international experts from academia, the private sector, and government met to review understanding of the microbial processes of methanogenesis and methanotrophy. The colloquium addressed how advanced knowledge of the microbiology of methane production and consumption could inform waste management, including landfills and composts, and three areas of agricultural management: enteric emissions from ruminant livestock, manure management, and rice cultivation. Support for both basic and applied research in microbiology and its applications is urgently needed to accelerate the realization of the large potential for these near-term solutions to counteract climate change.

An account of American Academy of Microbiology reforms and pandemic operations

Change is an inevitable part of any organization if it wants to adapt and strive in a changing environment. That was what the American Academy of Microbiology (Academy) did from 2019-2023 when it transformed itself into a scientific think tank at ASM while maintaining the high standard of an honorific community of scholars. Here, we report on the recent history of the Academy and the changes that have taken place during this period. With the contribution of many thougtful leaders, the Academy refreshed its commitment to promote excellence and uphold its high values.

Short-chain fatty acids are key mediators of the favorable effects of the Mediterranean diet on intestinal barrier integrity: data from the randomized controlled LIBRE trial

BACKGROUND

The Mediterranean diet is associated with the prevention of diabetes, cardiovascular disease, and cancer, all of which are linked to intestinal barrier impairment.

OBJECTIVES

Here, we hypothesize that the Mediterranean diet, possibly via the induction of short-chain fatty acids (SCFAs), improves intestinal barrier integrity. Furthermore, we aim to establish novel personalized nutrition advice based on machine learning algorithms.

METHODS

We studied 260 women with intestinal barrier impairment. The women were allocated to follow either a Mediterranean diet or a control diet for 3 mo. Intestinal permeability was assessed by measuring lipopolysaccharide binding protein (LBP) in plasma and zonulin in feces. SCFA concentrations were analyzed in feces. Bi- and multivariate analyses and machine learning algorithms (random forest classification) were conducted.

RESULTS

Particularly in the intervention group, adherence to the Mediterranean diet increased, whereas plasma LBP and fecal zonulin concentrations decreased (all q < 0.001 for the intervention group, all q < 0.1 for control group). In the intervention group, fecal SCFA concentrations increased (propionate + 19%; butyrate + 44%; both q < 0.001). Multivariate analyses showed that adherence to the Mediterranean diet was associated with SCFA concentrations (all q < 0.001) and inversely associated with LBP and zonulin concentrations (all q < 0.02). Mediation analyses identified propionate and butyrate as the key mechanistic link between diet and intestinal permeability integrity. Accordingly, using baseline SCFA data, we could predict the effect of the Mediterranean diet on intestinal permeability using a machine learning algorithm (receiver operating characteristic AUC: 0.78-0.96).

CONCLUSIONS

Our data suggest that SCFAs are key mediators for the relation between diet and gut health. Assessment of SCFAs may form a basis for personalized nutrition in future clinical care. These results need to be verified in larger studies powered for this purpose, comprising different study populations. The trial was registered at clinicaltrials.gov as NCT02087592 and NCT02516540.

Elucidating the role of the gut microbiota in the physiological effects of dietary fiber

BACKGROUND

Dietary fiber is an integral part of a healthy diet, but questions remain about the mechanisms that underlie effects and the causal contributions of the gut microbiota. Here, we performed a 6-week exploratory trial in adults with excess weight (BMI: 25-35 kg/m2) to compare the effects of a high-dose (females: 25 g/day; males: 35 g/day) supplement of fermentable corn bran arabinoxylan (AX; n = 15) with that of microbiota-non-accessible microcrystalline cellulose (MCC; n = 16). Obesity-related surrogate endpoints and biomarkers of host-microbiome interactions implicated in the pathophysiology of obesity (trimethylamine N-oxide, gut hormones, cytokines, and measures of intestinal barrier integrity) were assessed. We then determined whether clinical outcomes could be predicted by fecal microbiota features or mechanistic biomarkers.

RESULTS

AX enhanced satiety after a meal and decreased homeostatic model assessment of insulin resistance (HOMA-IR), while MCC reduced tumor necrosis factor-α and fecal calprotectin. Machine learning models determined that effects on satiety could be predicted by fecal bacterial taxa that utilized AX, as identified by bioorthogonal non-canonical amino acid tagging. Reductions in HOMA-IR and calprotectin were associated with shifts in fecal bile acids, but correlations were negative, suggesting that the benefits of fiber may not be mediated by their effects on bile acid pools. Biomarkers of host-microbiome interactions often linked to bacterial metabolites derived from fiber fermentation (short-chain fatty acids) were not affected by AX supplementation when compared to non-accessible MCC.

CONCLUSION

This study demonstrates the efficacy of purified dietary fibers when used as supplements and suggests that satietogenic effects of AX may be linked to bacterial taxa that ferment the fiber or utilize breakdown products. Other effects are likely microbiome independent. The findings provide a basis for fiber-type specific therapeutic applications and their personalization.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT02322112 , registered on July 3, 2015. Video Abstract.

HEYL Regulates Neoangiogenesis Through Overexpression in Both Breast Tumor Epithelium and Endothelium

Blocking tumor angiogenesis is an appealing therapeutic strategy, but to date, success has been elusive. We previously identified HEYL, a downstream target of Notch signaling, as an overexpressed gene in both breast cancer cells and as a tumor endothelial marker, suggesting that HEYL overexpression in both compartments may contribute to neoangiogenesis. Carcinomas arising in double transgenic Her2-neu/HeyL mice showed higher tumor vessel density and significantly faster growth than tumors in parental Her2/neu mice. Providing mechanistic insight, microarray-based mRNA profiling of HS578T-tet-off-HEYL human breast cancer cells revealed upregulation of several angiogenic factors including CXCL1/2/3 upon HEYL expression, which was validated by RT-qPCR and protein array analysis. Upregulation of the cytokines CXCL1/2/3 occurred through direct binding of HEYL to their promoter sequences. We found that vessel growth and migration of human vascular endothelial cells (HUVECs) was promoted by conditioned medium from HS578T-tet-off-HEYL carcinoma cells, but was blocked by neutralizing antibodies against CXCL1/2/3. Supporting these findings, suppressing HEYL expression using shRNA in MDA-MB-231 cells significantly reduced tumor growth. In addition, suppressing the action of proangiogenic cytokines induced by HEYL using a small molecule inhibitor of the CXCl1/2/3 receptor, CXCR2, in combination with the anti-VEGF monoclonal antibody, bevacizumab, significantly reduced tumor growth of MDA-MB-231 xenografts. Thus, HEYL expression in tumor epithelium has a profound effect on the vascular microenvironment in promoting neoangiogenesis. Furthermore, we show that lack of HEYL expression in endothelial cells leads to defects in neoangiogenesis, both under normal physiological conditions and in cancer. Thus, HeyL-/- mice showed impaired vessel outgrowth in the neonatal retina, while the growth of mammary tumor cells E0771 was retarded in syngeneic HeyL-/- mice compared to wild type C57/Bl6 mice. Blocking HEYL's angiogenesis-promoting function in both tumor cells and tumor-associated endothelium may enhance efficacy of therapy targeting the tumor vasculature in breast cancer.

Gut microbiota modulation with long-chain corn bran arabinoxylan in adults with overweight and obesity is linked to an individualized temporal increase in fecal propionate

BACKGROUND

Variability in the health effects of dietary fiber might arise from inter-individual differences in the gut microbiota's ability to ferment these substrates into beneficial metabolites. Our understanding of what drives this individuality is vastly incomplete and will require an ecological perspective as microbiomes function as complex inter-connected communities. Here, we performed a parallel two-arm, exploratory randomized controlled trial in 31 adults with overweight and class-I obesity to characterize the effects of long-chain, complex arabinoxylan (n = 15) at high supplementation doses (female: 25 g/day; male: 35 g/day) on gut microbiota composition and short-chain fatty acid production as compared to microcrystalline cellulose (n = 16, non-fermentable control), and integrated the findings using an ecological framework.

RESULTS

Arabinoxylan resulted in a global shift in fecal bacterial community composition, reduced α-diversity, and the promotion of specific taxa, including operational taxonomic units related to Bifidobacterium longum, Blautia obeum, and Prevotella copri. Arabinoxylan further increased fecal propionate concentrations (p = 0.012, Friedman's test), an effect that showed two distinct groupings of temporal responses in participants. The two groups showed differences in compositional shifts of the microbiota (p ≤ 0.025, PERMANOVA), and multiple linear regression (MLR) analyses revealed that the propionate response was predictable through shifts and, to a lesser degree, baseline composition of the microbiota. Principal components (PCs) derived from community data were better predictors in MLR models as compared to single taxa, indicating that arabinoxylan fermentation is the result of multi-species interactions within microbiomes.

CONCLUSION

This study showed that long-chain arabinoxylan modulates both microbiota composition and the output of health-relevant SCFAs, providing information for a more targeted application of this fiber. Variation in propionate production was linked to both compositional shifts and baseline composition, with PCs derived from shifts of the global microbial community showing the strongest associations. These findings constitute a proof-of-concept for the merit of an ecological framework that considers features of the wider gut microbial community for the prediction of metabolic outcomes of dietary fiber fermentation. This provides a basis to personalize the use of dietary fiber in nutritional application and to stratify human populations by relevant gut microbiota features to account for the inconsistent health effects in human intervention studies.

TRIAL REGISTRATION

Clinicaltrials.gov, NCT02322112 , registered on July 3, 2015. Video Abstract.

Precision Microbiome Modulation with Discrete Dietary Fiber Structures Directs Short-Chain Fatty Acid Production

Dietary fibers (DFs) impact the gut microbiome in ways often considered beneficial. However, it is unknown if precise and predictable manipulations of the gut microbiota, and especially its metabolic activity, can be achieved through DFs with discrete chemical structures. Using a dose-response trial with three type-IV resistant starches (RS4s) in healthy humans, we found that crystalline and phosphate cross-linked starch structures induce divergent and highly specific effects on microbiome composition that are linked to directed shifts in the output of either propionate or butyrate. The dominant RS4-induced effects were remarkably consistent within treatment groups, dose-dependent plateauing at 35 g/day, and can be explained by substrate-specific binding and utilization of the RS4s by bacterial taxa with different pathways for starch metabolism. Overall, these findings support the potential of using discrete DF structures to achieve targeted manipulations of the gut microbiome and its metabolic functions relevant to health.

HOXC10 Expression Supports the Development of Chemotherapy Resistance by Fine Tuning DNA Repair in Breast Cancer Cells

Development of drug resistance is a major factor limiting the continued success of cancer chemotherapy. To overcome drug resistance, understanding the underlying mechanism(s) is essential. We found that HOXC10 is overexpressed in primary carcinomas of the breast, and even more significantly in distant metastasis arising after failed chemotherapy. High HOXC10 expression correlates with shorter recurrence-free and overall survival in patients with estrogen receptor-negative breast cancer undergoing chemotherapy. We found that HOXC10 promotes survival in cells treated with doxorubicin, paclitaxel, or carboplatin by suppressing apoptosis and upregulating NF-κB Overexpressed HOXC10 increases S-phase-specific DNA damage repair by homologous recombination (HR) and checkpoint recovery in cells at three important phases. For double-strand break repair, HOXC10 recruits HR proteins at sites of DNA damage. It enhances resection and lastly, it resolves stalled replication forks, leading to initiation of DNA replication following DNA damage. We show that HOXC10 facilitates, but is not directly involved in DNA damage repair mediated by HR. HOXC10 achieves integration of these functions by binding to, and activating cyclin-dependent kinase, CDK7, which regulates transcription by phosphorylating the carboxy-terminal domain of RNA polymerase II. Consistent with these findings, inhibitors of CDK7 reverse HOXC10-mediated drug resistance in cultured cells. Blocking HOXC10 function, therefore, presents a promising new strategy to overcome chemotherapy resistance in breast cancer. Cancer Res; 76(15); 4443-56. ©2016 AACR.

Short alleles, bigger smiles? The effect of 5-HTTLPR on positive emotional expressions

The present research examined the effect of the 5-HTTLPR polymorphism in the serotonin transporter gene on objectively coded positive emotional expressions (i.e., laughing and smiling behavior objectively coded using the Facial Action Coding System). Three studies with independent samples of participants were conducted. Study 1 examined young adults watching still cartoons. Study 2 examined young, middle-aged, and older adults watching a thematically ambiguous yet subtly amusing film clip. Study 3 examined middle-aged and older spouses discussing an area of marital conflict (that typically produces both positive and negative emotion). Aggregating data across studies, results showed that the short allele of 5-HTTLPR predicted heightened positive emotional expressions. Results remained stable when controlling for age, gender, ethnicity, and depressive symptoms. These findings are consistent with the notion that the short allele of 5-HTTLPR functions as an emotion amplifier, which may confer heightened susceptibility to environmental conditions.

The Notch pathway inhibits TGFβ signaling in breast cancer through HEYL-mediated crosstalk

Acquired resistance to TGFβ is a key step in the early stages of tumorigenesis. Mutations in TGFβ signaling components are rare, and little is known about the development of resistance in breast cancer. On the other hand, an activated Notch pathway is known to play a substantial role in promoting breast cancer development. Here, we present evidence of crosstalk between these two pathways through HEYL. HEYL, a basic helix-loop-helix transcription factor and a direct target of Notch signaling, is specifically overexpressed in breast cancer. HEYL represses TGFβ activity by binding to TGFβ-activated Smads. HeyL(-/-) mice have defective mammary gland development with fewer terminal end buds. On the other hand, HeyL transgenic mice show accelerated mammary gland epithelial proliferation and 24% of multiparous mice develop mammary gland cancer. Therefore, repression of TGFβ signaling by Notch acting through HEYL may promote initiation of breast cancer.

Abstract 3123: The Notch pathway inhibits TGF-β signaling in breast cancer through HEYL-mediated crosstalk

Acquired resistance to Transforming growth factor-β (TGF-β) is a key step in the early stages of tumorigenesis. Mutations of TGF-β signaling components, often found in other cancers, are rare in breast cancer, and little is known about the development of this resistance in breast cancer. On the other hand, activation of Notch pathway is known to play a substantial role in promoting breast cancer development. We hypothesized that crosstalk between these two pathways occurs through HEYL, a basic helix-loop-helix (bHLH) transcription factor, and a known direct target of Notch. We found that HEYL is overexpressed in 40% of breast cancers. Expression of Notch increased HEYL expression while knockdown of RBP-J, a critical mediator of Notch, reduced HEYL expression in HS578T and MDAMB-231 breast cancer cells. Taking into account the contradictory biological effects of Notch and TGF-β signaling, we sought to examine whether HEYL inhibits the TGF-β pathway. TGF-β treatment or Smad3 overexpression significantly increased the luciferase activity of the TGF-β responsive reporter vector, p3TP-Luc, and the P15 (CDKN2B) gene promoter, but this transactivation was strongly inhibited by HEYL. Bimolecular fluorescence complementation assays confirmed the interaction between Smad 3 and HEYL; immunoprecipitation assays with deletion constructs showed that the Basic domain of HEYL interacts with the MH2 domain of Smad3, and that their interaction is necessary for HEYL to inhibit TGF-β signaling. In addition, using a tet-off inducible breast cancer cell model, HEYL was shown to transcriptionally up-regulate many genes that drive metastasis and tumor angiogenesis. Supporting this concept, HEYL/HER2 double transgenic mice showed nearly 50% increase in lung metastasis (20% vs 46%) compared to HER2/neu mice. Similarly, lung colonization occurred in 100% of mice injected with MDAMB231 while HEYL-shRNAs reduced incidence to 50%. Therefore, HEYL promotes breast cancer growth and metastasis in Smad-dependent and Smad-independent mechanisms.

Citation Format: Han Liangfeng, Adam Diehl, Nguyen K. Nguyen, Preethi Korangath, Teo Weiwen, Zhe Zhang, Scott Kominsky, Pedram Argani, Goran Landberg, Saraswati V. Sukumar. The Notch pathway inhibits TGF-β signaling in breast cancer through HEYL-mediated crosstalk. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3123. doi:10.1158/1538-7445.AM2013-3123

Molecular pathways: current role and future directions of the retinoic acid pathway in cancer prevention and treatment

Retinoids and their naturally metabolized and synthetic products (e.g., all-trans retinoic acid, 13-cis retinoic acid, bexarotene) induce differentiation in various cell types. Retinoids exert their actions mainly through binding to the nuclear retinoic acid receptors (α, β, γ), which are transcriptional and homeostatic regulators with functions that are often compromised early in neoplastic transformation. The retinoids have been investigated extensively for their use in cancer prevention and treatment. Success has been achieved with their use in the treatment of subtypes of leukemia harboring chromosomal translocations. Promising results have been observed in the breast cancer prevention setting, where fenretinide prevention trials have provided a strong rationale for further investigation in young women at high risk for breast cancer. Ongoing phase III randomized trials investigating retinoids in combination with chemotherapy in non-small cell lung cancer aim to definitively characterize the role of retinoids in this tumor type. The limited treatment success observed to date in the prevention and treatment of solid tumors may relate to the frequent epigenetic silencing of RARβ. Robust evaluation of RARβ and downstream genes may permit optimized use of retinoids in the solid tumor arena.

Abstract PD01-05: A Combination of HDAC Inhibitor Entinostat (MS-275), All Trans Retinoic Acid (ATRA) and Chemotherapy Drug(s) Causes Regression of Established Xenografts of Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a subgroup of breast cancer that rapidly develops resistance to chemotherapy. Currently, TNBC patients are treated with anthracycline and taxane-based regimens. These treatments result in some improvements in the clinical outcomes; however, they are associated with poor prognosis. Also, endocrine therapies are ineffective since the tumors do not express the estrogen receptor. Recent studies have shown that histone deacetylase (HDAC) inhibitors could reverse the epigenetic profile of some genes, including ER, EGFR, and RAR≥2. We have recently shown that treatments that combine the HDAC inhibitor, Entinostat (MS-275), with the aromatase inhibitor, Letrozole, result in regression of xenografts of MDA-MB-231 breast cancer cells. Since RAR≥2 is re-expressed as well, we reasoned that combining epigenetic therapy using MS-275, with differentiation therapy using a RAR≥2 agonist (ATRA) will provide an effective combination of drugs against TNBC. We also examined possible potentiation of anticancer activity of these agents by low nontoxic doses of chemotherapy (doxorubicin and paclitaxel). In vitro, human TNBC cell lines, MDA-MB-231, HCC 1143, SUM159, SUM149 and BT20 responded significantly better to the triple combination compared to the drugs used singly or in combination with MS-275. Upon treatment, re-expression of the silenced RAR≥2 and downstream effectors was observed in the cell lines in vitro and in tumor xenografts of MDA-MB-231 cells. Subcutaneous tumor growth in immunodeficient mice was strongly inhibited (10/14 significant regression) using a combination of MS-275, ATRA and low dose Doxorubicin, compared to the drugs administered singly or in combination with MS-275. No significant weight loss was observed in any of the groups. This combination was then used to treat tumor xenografts of SUM159, another TNBC cell line, and gave a promising result. Furthermore, combination of MS-275, ATRA, and a clinical dose of Paclitaxel can effectively inhibit growth of MDA-MB-231 and SUM159 cells. These results suggest that combination of HDAC inhibitor and RAR≥2 agonist with low dose chemotherapy has the potential to be an effective treatment against TNBC. This study provides encouraging new information for a nontoxic, and novel combination of drugs which could be effective against TNBC.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD01-05.

Substrate elasticity regulates skeletal muscle stem cell self-renewal in culture

Stem cells that naturally reside in adult tissues, such as muscle stem cells (MuSCs), exhibit robust regenerative capacity in vivo that is rapidly lost in culture. Using a bioengineered substrate to recapitulate key biophysical and biochemical niche features in conjunction with a highly automated single-cell tracking algorithm, we show that substrate elasticity is a potent regulator of MuSC fate in culture. Unlike MuSCs on rigid plastic dishes (approximately 10(6) kilopascals), MuSCs cultured on soft hydrogel substrates that mimic the elasticity of muscle (12 kilopascals) self-renew in vitro and contribute extensively to muscle regeneration when subsequently transplanted into mice and assayed histologically and quantitatively by noninvasive bioluminescence imaging. Our studies provide novel evidence that by recapitulating physiological tissue rigidity, propagation of adult muscle stem cells is possible, enabling future cell-based therapies for muscle-wasting diseases.

Abstract 5593: A combination of HDAC inhibitor Entinostat (MS-275), All Trans Retinoic Acid (ATRA) and low dose Doxorubicin causes regression of established xenografts of triple negative breast cancer

Triple negative breast cancer (TNBC) is a subgroup of breast cancer that rapidly develops resistance to chemotherapy. Currently, TNBC patients are treated with anthracycline and taxane-based regimens. These treatments result in some improvements in the clinical outcomes; however, they are associated with poor prognosis. Also, endocrine therapies are ineffective since the tumors do not express the estrogen receptor. Recent studies have shown that histone deacetylase (HDAC) inhibitors could reverse the epigenetic profile of some genes, including ER, EGFR, and RARβ2. We have recently shown that treatments that combine the HDAC inhibitor, Entinostat (MS-275), with the aromatase inhibitor, Letrozole, result in regression of xenografts of MDA-MB-231 breast cancer cells. Since RARβ2 is re-expressed as well, we reasoned that combining epigenetic therapy using MS-275, with differentiation therapy using a RARβ2 agonist (ATRA) will provide an effective combination of drugs against TNBC. We also examined possible potentiation of anticancer activity of these agents by low nontoxic doses of chemotherapy (doxorubicin). In vitro, human TNBC cell lines, MDA-MB-231, HCC1954, HCC 1143, and BT20 responded significantly better to the triple combination compared to the drugs used singly or in combination with MS-275. Upon treatment, re-expression of the silenced RARβ2 and downstream effectors was observed in the cell lines in vitro and in tumor xenografts of MDA-MB-231 cells. Subcutaneous tumor growth in immunodeficient mice was strongly inhibited (10/14 significant regression) using a combination of MS-275, ATRA and low dose Doxorubicin, compared to the drugs administered singly or in combination with MS-275. No significant weight loss was observed in any of the groups. These results suggest that combination of HDAC inhibitor and RARβ2 agonist with low dose chemotherapy has the potential to be an effective treatment against TNBC. This study provides encouraging new information for a nontoxic, and novel combination of drugs which could be effective against TNBC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5593.

Effect of chronic psychosocial stress-induced by subordinate colony (CSC) housing on brain neuronal activity patterns in mice

Chronic subordinate colony (CSC) housing has been recently validated as a murine model of chronic psychosocial stress which induces alterations of stress-related parameters including decreased body-weight gain and an increased level of anxiety in comparison with single housed control (SHC) mice. By using immunohistochemical immediate early gene (IEG) mapping we investigated whether CSC housing causes alterations in neuronal activation patterns in limbic areas including the amygdala, hippocampus, septum and the periaqueductal gray (PAG) and hypothalamic paraventricular nucleus (PVN). While CSC housing increased basal Zif-268 expression in the nucleus accumbens shell compared to SHC, IEG responses to subsequent open arm (OA) exposure were attenuated in the ventral and intermediate sub-regions of the lateral septum, parvocellular PVN and the dorsal CA3 region of the hippocampus of CSC compared with SHC mice. In contrast, a potentiated c-Fos response in CSC mice was observed in the dorsomedial PAG after OA exposure. Confirming previous findings obtained on the elevated plus-maze, an enhanced anxiety-related behavior in CSC compared with SHC mice was also observed during OA exposure. In order to investigate the appropriate control conditions for CSC housing, group housed control (GHC) mice were additionally included in the behavioral testing. Interestingly, GHC as well as CSC mice showed significantly less risk assessment/exploratory behavior during OA exposure compared with SHC mice indicating that group housing itself is stressful for mice and not an adequate control for the CSC paradigm. Overall, CSC housing is an ethologically relevant chronic psychosocial stressor which results in an elevated sensitivity to a subsequent novel, aversive challenge. However, the CSC-induced increase in anxiety-related behavior was accompanied by differences in neuronal activation, compared with SHC, in defined sub-regions of brain areas known to be involved in the processing of emotionality and stress responses.

Role of voltage-gated L-type Ca2+ channel isoforms for brain function

Voltage-gated LTCCs (L-type Ca2+ channels) are established drug targets for the treatment of cardiovascular diseases. LTCCs are also expressed outside the cardiovascular system. In the brain, LTCCs control synaptic plasticity in neurons, and DHP (dihydropyridine) LTCC blockers such as nifedipine modulate brain function (such as fear memory extinction and depression-like behaviour). Voltage-sensitive Ca2+ channels Cav1.2 and Cav1.3 are the predominant brain LTCCs. As DHPs and other classes of organic LTCC blockers inhibit both isoforms, their pharmacological distinction is impossible and their individual contributions to defined brain functions remain largely unknown. Here, we summarize our recent experiments with two genetically modified mouse strains, which we generated to explore the individual biophysical features of Cav1.2 and Cav1.3 LTCCs and to determine their relative contributions to various physiological peripheral and neuronal functions. The results described here also allow predictions about the pharmacotherapeutic potential of isoform-selective LTCC modulators.

Methylation of the p16(INK4a) promoter region in telomerase immortalized human keratinocytes co-cultured with feeder cells

Human keratinocytes grown in co-culture with fibroblast feeder cells have an extended in vitro lifespan and delayed accumulation of the tumor suppressor protein p16(INK4a) when compared to the same cells grown on tissue culture plastic alone. Previous studies have indicated that human keratinocytes can be immortalized by telomerase activity alone when grown in co-culture with feeder cells, suggesting that loss of the p16(INK4a)/Rb pathway is not required for immortalization. Using two independent human keratinocyte cell strains, we found that exogenous telomerase expression and co-culture with feeder cells results in efficient extension of lifespan without an apparent crisis. However, when these cells were transferred from the co-culture environment to plastic alone they experienced only a brief period of slowed growth before continuing to proliferate indefinitely. Examination of immortal cell lines demonstrated p16(INK4a) promoter methylation had occurred in both the absence and presence of feeder cells. Reintroduction of p16(INK4a) into immortal cell lines resulted in rapid growth arrest. Our results suggest that p16(INK4a)/Rb-induced telomere-independent senescence, although delayed in the presence of feeders, still provides a proliferation barrier to human keratinocytes in this culture system and that extended culture of telomerase-transduced keratinocytes on feeders can lead to the methylation of p16(INK4a).

MR imaging in shoulder trauma. Value of STIR images

PURPOSE

To determine the adequacy of MR standard protocols by analyzing conventional T1- and T2-weighted SE sequences, and to evaluate the usefulness of additional fat-suppressed (STIR) images in shoulder trauma.

MATERIAL AND METHODS

Paracoronal T1-weighted, T2-weighted, SE, and STIR images were obtained on a 0.5 T superconductive system in 25 patients with shoulder trauma. In a separate evaluation of T1/T2 images and a combined evaluation of T1/T2 SE- and STIR images, we compared the number of patients with evidence of Hill-Sachs lesions, bone bruises, and/or rotator-cuff lesions.

RESULTS

Compared to the combined evaluation of T1/T2 and STIR images, the separate evaluation of T1/T2 SE images revealed identical results for rotator-cuff lesions and Hill-Sachs lesions, but different results for the bone bruises in the area of the major tubercle.

CONCLUSION

Occult fractures of the major tubercle, indicated by areas of bone bruising, might be missed with MR using conventional SE images. We recommend the use of additional paracoronal fat-suppressed sequences in patients with clinically suspected lesions and equivocal findings on plain radiographs and on standard SE sequences.

[Anesthesia for heart catheterization in children. Comparison of 3 techniques]

A study was carried out to compare the haemodynamic and respiratory effects, as well as the quality of recovery, of anaesthesia with ketamine, sodium gamma-hydroxybutyrate (GOH) and etomidate in children undergoing cardiac catheterization. Thirty children, mean age 48 +/- 35 months, ranked ASA 2 or 3 on account of congenital heart disease, were assigned to one of three groups (n = 10). They were given: in group E1, a 0.3 mg.kg-1 bolus of etomidate, followed by 0.1 mg.kg-1.min-1 for 10 minutes, and 0.026 mg.kg-1.min-1 thereafter; in group G2, a 50 mg.kg-1 bolus of GOH, and in group K3, a 4 mg.kg-1 bolus of ketamine followed by a continuous infusion of 0.083 mg.kg-1.min-1. The patients breathed spontaneously. Monitoring included heart rate, systolic, diastolic and mean blood pressure, pulse oximetry, and capnography. Femoral venous or arterial catheterization was performed after local anaesthesia (with no more than 2 mg.kg-1 of lidocaine). Measurements were performed before induction, and then 1, 10, 30 and 60 minutes afterwards. The quality of anaesthesia was assessed according to Steward's scale. The investigation lasted between 50 and 100 min in all three groups. There were no significant differences in haemodynamic and respiratory parameters during the investigation between the groups. Recovery was shorter and of better quality in group E1. On the opposite, 30 minutes after the end of the catheterization, all the patients in group K3 were stuporous, with 5 of them displaying involuntary movements. The patients of the other two groups reacted correctly to stimuli, but those in group G2 went back to sleep very rapidly. There were no complications.(ABSTRACT TRUNCATED AT 250 WORDS)