Cell shape is a key determinant of estrogen biosynhesis in adipose stromal cells

Abstract #5061

BACKGROUND: Accumulating evidence suggests that obesity is a high risk factor for breast cancer among post-menopausal women, which can at least partially be explained by the contribution of adipose tissue to local and circulating estrogen. In response to tumor cell-secreted cytokines, adipose stromal cells (ASCs) express a large amount of aromatase, a key enzyme in estrogen biosynthesis and a clinically proven target for breast cancer therapy. Increased estrogen production from ASCs in turn stimulates hormone-dependent tumor growth, creating a “vicious cycle” between estrogen-dependent tumor cells and estrogen-producing ASCs that is conducive to mammary tumorigenesis. In contrast to our knowledge of aromatase expression in tumor-associated ASCs, relatively little is known about its regulation in ASCs under disease-free conditions. Could aromatase expression in ASCs be induced without the presence of tumor cells? Is there any genetic or epigenetic difference in the inducibility of aromatase expression in cancer-free individuals? If so, might the difference be related to breast cancer risk?
 Material and Methods: ASCs were isolated from cancer-free individuals by using blendzyme. ACSs were plated in confluent and subconfluent states for several days and then were harvested for RNA isolation, enzymatic activity and protein study. Specific genes were expressed in ASCs using lentiviral expression system and were depleted by siRNA method. Co-culture system was established using ASC and ZR-75 cell line. In a xenograft model, ASCs were injected with the ZR-75 cells in mammary fat pad.
 Results: Aromatase expression in ASCs can be stimulated up to several hundred folds by cell shape changes induced by various physical or chemical stimuli. Our work uncovered several key signal-transducing molecules including Inhibitory kB Kinases (IKKs) in mediating the cell shape-triggered aromatase expression. Unexpectedly, activation of aromatase gene expression following cell shape change does not involve activation of NFkB, a downstream effector of IKKs. Rather, aromatase induction following cell shape change positively correlated with the expression level of CEBPβ; and CEBPβ knockdown severely impaired aromatase expression. Significant increase in aromatase expression was due to activation of the same breast cancer-associated promoters that are robustly stimulated in intratumoral adipose tissue. In a coculture and invivo xenograft model, ACSs were able to trigger E2 responsive genes as well as stimulate early tumor occurence in ZR-75 cells, respectively.
 Discussion: Our study suggests that genetic and epigenetic alterations in aromatase-inducing signaling pathway may result in excessive estrogen production and thus breast cancer development. Excess aromatase produced by the stromal cells are capable of initiating tumor in surrounding breast epithelial cells. Study further uncovers a previously unappreciated paradigm for regulation of aromatase expression in adipose tissue, which should have a far-reaching impact on risk assessment and prevention of breast cancer.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5061.

In vitro activity of antimicrobial agents against oxacillin resistant staphylococci with special reference to Staphylococcus haemolyticus

One hundred and sixty seven isolates of staphylococci isolated from the inpatients of a tertiary care referral hospital in South India were speciated and activity of oxacillin, glycopeptides, linezolid and quinupristin/dalfopristin against these isolates was tested by broth microdilution method. Of the 114 coagulase negative staphylococci (CoNS), 49.1 % were S. haemolyticus, isolated predominantly from urine (64.6%), while the rest belonged to 11 other species. More than half the isolates of S. aureus (52.8%) and 68.4% of the CoNS were oxacillin resistant. All the strains were uniformly susceptible to vancomycin, linezolid and quinupristin/dalfopristin; but 25.6% isolates of S. haemolyticus showed reduced susceptibility to teicoplanin (MIC: 8-16 mg/L). Our study demonstrates the high prevalence of oxacillin resistance among hospital isolates of S. aureus and CoNS in India. Vancomycin, along with the newer agents like linezolid and quinupristin/dalfopristin remains the drug of choice for treating multi drug resistant staphylococcal infections.

Lateral vibration of a water drop and its motion on a vibrating surface

The resonant modes of sessile water drops on a hydrophobic substrate subjected to a small-amplitude lateral vibration are investigated using computational fluid dynamic (CFD) modeling. As the substrate is vibrated laterally, its momentum diffuses within the Stokes layer of the drop. Above the Stokes layer, the competition between the inertial and Laplace forces causes the formation of capillary waves on the surface of the drop. In the first part of this paper, the resonant states of water drops are illustrated by investigating the velocity profile and the hydrostatic force using a 3d simulation of the Navier-Stokes equation. The simulation also allows an estimation of the contact angle variation on both sides of the drop. In the second part of the paper, we investigate the effect of vibration on a water drop in contact with a vertical plate. Here, as the plate vibrates parallel to gravity, the contact line oscillates. Each oscillation is, however, rectified by hysteresis, thus inducing a ratcheting motion to the water droplet vertically downward. Maximum rectification occurs at the resonant states of the drop. A comparison between the frequency-dependent motion of these drops and the variation of contact angles on their both sides is made. The paper ends with a discussion on the movements of the drops on a horizontal hydrophobic surface subjected to an asymmetric vibration.

Changes in nitrergic innervation of defunctionalized rat colon after diversion colostomy

After 45 days of complete diversion colostomy in male Wistar rats, morphometry of soma and nuclei of NADPH diaphorase positive cells of the myenteric plexus was evaluated. There was a significant (P < 0.0001) diminution in the area, perimeter and volume-weighted mean volume of soma and nuclei of nitrergic myenteric neurones in the defunctionalized colon. In addition, there was a significant reduction in the neuronal density of the myenteric neurones, and increased distance between the ganglia. In addition, there was myenteric glial atrophy. Atrophy of colonic myenteric neurones was accompanied by significant reduction (P < 0.001) in the volume fraction of the muscularis externa, the prime targets of these neurones. The disturbances in the microecology of the colon may jeopardize the finely orchestrated functioning of the components of the Enteric nervous system (ENS) leading to colonic dysfunction. Our observations, by extrapolation, may explain the bowel dysmotility in humans after restoration of colonic continuity after colostomy.

A relationship perspective on IT outsourcing

A longitudinal study at four companies provides valuable insights about the evolution of IT outsourcing relationships.

In vitro activity of cefpirome: a new fourth generation cephalosporin

This study was carried out to find the efficacy of Cefpirome in an Indian setting in a tertiary care referral hospital. A total of 516 bacterial isolates from various clinical specimens were tested against cefpirome (Cpo) and compared against the activities of three other cephalosporins, namely cefazolin (Cz), cefuroxime (Cu), and cefotaxime (Ce) as representative of the other three generations. Preliminary testing was done by Kirby Bauer technique. In the gram positive group of organisms (Staphylococcus aureus and coagulase negative staphylococci); 96 strains out of 177 (54.2%) were resistant to Cpo compared to 61.0% for Cz and 72.3% for Cu. In the Enterobacteriaceae group, 66.0% of the isolates were resistant to Cpo compared to 63.2% for Ce; while for Pseudomonas and other non-fermentors, the corresponding figures were 70.7% and 50.0% for Cpo and Ce respectively. The MIC for the strains resistant to Cpo were found to be > 16 mg/L to > 256 mg/L. This study highlights that Cpo did not have superior activity against the organisms isolated in our laboratory. However, since its activity against gram positive and gram negative organisms is comparable to those of Cz and Ce respectively, it may be useful for mixed infections for empirical therapy.

Infectious aetiology in acute coronary syndromes

PURPOSE

To ascertain the relationship between seropositivity to chronic infections with Helicobacter pylori, Chlamydia pneumoniae and Cytomegalovirus (CMV) and acute coronary syndromes and association of each of these infective agent with biochemical parameters and cardiovascular risk factors.

METHODS

The present study was a case-control study involving 117 patients [unstable angina (UA) n=101 and chronic stable angina (CSA) n = 16] attending cardiology clinic. The cases were aged 35-79 years and they were compared with age, sex and socio-economic status matched controls without evidence of coronary artery disease (CAD).

RESULTS

Fifty seven (58%) patients with UA and 9(56%) patients with CSA were seropositive for H. pylori. Sixty seven (66%) subjects with UA and 15(94%) patients with CSA subjects were seropositive for C. pneumoniae. Two (2%) patients with USA were seropositive for Cytomegalovirus (CMV). Seropositivity in normal subjects for H. pylori, C. pneumoniae and CMV was 7(43.25%), 10(62.5%) and 1(6.25%) respectively. In linear regression analysis seropositivity of CMV showed positive association with HDL-C (P< 0.05). No significant association of infective agents and coronary syndromes was observed.

CONCLUSIONS

Higher levels of lipids, lipoproteins, C-reactive protein and higher percentage of coronary risk factors in patients seropositive for H. pylori in UA suggests the role of infective agents in pathogenesis of atherosclerosis.

The Arabidopsis AMP1 gene encodes a putative glutamate carboxypeptidase

Arabidopsis amp1 mutants show pleiotropic phenotypes, including altered shoot apical meristems, increased cell proliferation, polycotyly, constitutive photomorphogenesis, early flowering time, increased levels of endogenous cytokinin, and increased cyclin cycD3 expression. We have isolated the AMP1 gene by map-based cloning. The AMP1 cDNA encodes a 706;-amino acid polypeptide with significant similarity to glutamate carboxypeptidases. The AMP1 mRNA was expressed in all tissues examined, with higher expression in roots, stems, inflorescences, and siliques. Microarray analysis identified four mRNA species with altered expression in two alleles of amp1, including upregulation of CYP78A5, which has been shown to mark the shoot apical meristem boundary. The similarity of the AMP1 protein to glutamate carboxypeptidases, and in particular to N-acetyl alpha-linked acidic dipeptidases, suggests that the AMP1 gene product modulates the level of a small signaling molecule that acts to regulate a number of aspects of plant development, in particular the size of the apical meristem.

The Arabidopsis AMP1 gene encodes a putative glutamate carboxypeptidase

Arabidopsis amp1 mutants show pleiotropic phenotypes, including altered shoot apical meristems, increased cell proliferation, polycotyly, constitutive photomorphogenesis, early flowering time, increased levels of endogenous cytokinin, and increased cyclin cycD3 expression. We have isolated the AMP1 gene by map-based cloning. The AMP1 cDNA encodes a 706;-amino acid polypeptide with significant similarity to glutamate carboxypeptidases. The AMP1 mRNA was expressed in all tissues examined, with higher expression in roots, stems, inflorescences, and siliques. Microarray analysis identified four mRNA species with altered expression in two alleles of amp1, including upregulation of CYP78A5, which has been shown to mark the shoot apical meristem boundary. The similarity of the AMP1 protein to glutamate carboxypeptidases, and in particular to N-acetyl alpha-linked acidic dipeptidases, suggests that the AMP1 gene product modulates the level of a small signaling molecule that acts to regulate a number of aspects of plant development, in particular the size of the apical meristem.

Fruit development is actively restricted in the absence of fertilization in Arabidopsis

Flowering plants usually require fertilization to form fruit and seed and to initiate floral organ abscission in structures that do not contribute to the fruit. An Arabidopsis mutant that initiates seedless fruit without fertilization (fwf) or parthenocarpy was isolated and characterized to understand the factors regulating the transition between the mature flower and the initiation of seed and fruit development. The fwf mutant is fertile and has normal plant growth and stature. It sets fertile seed following self-pollination and fertilization needs to be prevented to observe parthenocarpy. The initiation of parthenocarpic siliques (fruit) was found to be dependent upon carpel valve identity conferred by FRUITFULL but was independent of the perception of gibberellic acid, shown to stimulate parthenocarpy in Arabidopsis following exogenous application. The recessive nature of fwf is consistent with the involvement of FWF in processes that inhibit fruit growth and differentiation in the absence of fertilization. The enhanced cell division and expansion in the silique mesocarp layer, and increased lateral vascular bundle development imply FWF has roles also in modulating silique growth post-fertilization. Parthenocarpy was inhibited by the presence of other floral organs suggesting that both functional FWF activity and inter-organ communication act in concert to prevent fruit initiation in the absence of fertilization.

Analysis of the activity of promoters from two photosynthesis-related genes psaF and petH of spinach in a monocot plant, rice

The subunit III of photosystem I and ferredoxin-NADP(+)-oxidoreductase are encoded by nuclear genes, namely psaF and petH. The activity of their promoters from spinach has been evaluated in transgenic tobacco earlier. Evaluation of the activity of these Dicotyledoneae-specific promoters has been carried out in a monocot system (i.e. rice) by transient gene expression system, based on electroporation-mediated gene delivery into protoplasts from leaves and roots. It has been found that various promoter deletions show higher activity in leaf protoplasts and elements for quantitative response are widely distributed. Transgenic rice has also been produced with a petH promoter and gus reporter gene construct. Although petH promoter is a weak promoter in comparison to the 35S promoter, it expresses well in green tissues and could be useful for plant genetic engineering.

Expression and parent-of-origin effects for FIS2, MEA, and FIE in the endosperm and embryo of developing Arabidopsis seeds

The promoters of MEA (FIS1), FIS2, and FIE (FIS3), genes that repress seed development in the absence of pollination, were fused to beta-glucuronidase (GUS) to study their activity pattern. The FIS2GUS product is found in the embryo sac, in each of the polar cell nuclei, and in the central cell nucleus. After pollination, the maternally derived FIS2GUS protein occurs in the nuclei of the cenocytic endosperm. Before cellularization of the endosperm, activity is terminated in the micropylar and central nuclei of the endosperm and subsequently in the nuclei of the chalazal cyst. MEAGUS has a pattern of activity similar to that of FIS2GUS, but FIEGUS protein is found in many tissues, including the prepollination embryo sac, and in embryo and endosperm postpollination. The similarity in mutant phenotypes; the activity of FIE, MEA, and FIS2 in the same cells in the embryo sac; and the fact that MEA and FIE proteins interact in a yeast two-hybrid system suggest that these proteins operate in the same system of control of seed development. Maternal and not paternal FIS2GUS, MEAGUS, and FIEGUS show activity in early endosperm, so these genes may be imprinted. When fis2, mea, and fie mutants are pollinated, seed development is arrested at the heart embryo stage. The seed arrest of mea and fis2 is avoided when they are fertilized by a low methylation parent. The wild-type alleles of MEA or FIS2 are not required. The parent-of-origin-determined differential activity of MEA, FIS2, and FIE is not dependent on DNA methylation, but methylation does control some gene(s) that have key roles in seed development.