Moving from Malaria Burden Reduction toward Elimination: An Evaluation of Mass Drug Administration in Southern Province, Zambia

From December 2014 to February 2016, a cluster randomized controlled trial was carried out in 60 health facility catchment areas along Lake Kariba in Zambia's Southern Province. The trial sought to evaluate the impact of four rounds of a mass drug administration (MDA) intervention with dihydroartemisinin-piperaquine (DHAP) or focal MDA with DHAP at the household level compared with a control population that received the standard of care. This study was the first randomized controlled trial with DHAP for MDA in sub-Saharan Africa and was conducted through a collaboration between the National Malaria Elimination Programme in the Zambian Ministry of Health, the PATH Malaria Control and Elimination Partnership in Africa, and the Center for Applied Malaria Research and Evaluation at Tulane University. This article serves as an introduction to a collection of articles designed to explore different aspects of the intervention. By describing the recent history of malaria control in Zambia leading up to the trial-from the scale-up of point-of-care diagnosis and treatment, vector control, and indoor residual spraying early in the twenty-first century, to the efforts made to sustain the gains achieved with that approach-it provides a rationale for the implementation of a trial that has informed a new national strategic plan and solidified malaria elimination as Zambia's national goal.

Two Sides of the Same Coin: The Role of Developmental pathways and pluripotency factors in normal mammary stem cells and breast cancer metastasis

Breast cancer initiation and progression are often observed as the result of dysregulation of normal developmental processes and pathways. Studies focused on normal mammary stem/progenitor cell activity have led to an understanding of how breast cancer cells acquire stemness-associated properties including tumor initiation, survival and multi-lineage differentiation into heterogeneous tumors that become difficult to target therapeutically. Importantly, more recent investigations have provided valuable insight into how key developmental regulators can impact multiple phases of metastasis, where they are repurposed to not only promote metastatic phenotypes such as migration, invasion and EMT at the primary site, but also to regulate the survival, initiation and maintenance of metastatic lesions at secondary organs. Herein, we discuss findings that have led to a better understanding of how embryonic and pluripotency factors contribute not only to normal mammary development, but also to metastatic progression. We further examine the therapeutic potential of targeting these developmental pathways, and discuss how a better understanding of compensatory mechanisms, crosstalk between pathways, and novel experimental models could provide critical insight into how we might exploit embryonic and pluripotency regulators to inhibit tumor progression and metastasis.

Abstract P2-02-14: Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer

c-Src (Src) is a proto-oncogene involved in signaling that culminates in the control of multiple biological functions. Src is also one of the most frequently upregulated pathways in triple negative breast cancer (TNBC). Dysregulation of Src has been detected in TNBC and is strongly associated with tumor metastasis and poor prognosis. However, even after promising preclinical studies, Src inhibitors did not show major clinical advantage in unselected TNBC populations. We have previously published that metastatic TNBC has high energy-dependency to mitochondrial fatty acid beta-oxidation (FAO) and FAO activates Src by inducing autophosphorylation at Y419. However, our recent analysis suggests that as observed with the Src inhibitors, TNBC tumors treated with FAO inhibitors also develop drug-resistance and continue tumor growth. Evaluation of their drug resistance mechanism revealed that while short-term inhibition of FAO or Src induces autophagic and apoptotic cell deaths, long-term inhibition results in autophagy-mediated drug resistance and survival. Further analyses suggest that FAO and Src inhibitors activate mitogen-activated protein (MAP) kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway via the induction of cellular reactive oxygen species (ROS) in TNBC. Activated MEK/ERK then induces survival pathways for drug resistance and tumor survival. Validation of in vitro findings using in vivo TNBC models confirmed that combination of FAO/Src inhibitors with MEK/ERK inhibitors can provide significant benefit to overcome the therapeutic resistance of TNBC. These findings open-up new therapeutic opportunities to manage TNBC patients with currently non-targetable metastatic tumors.

Citation Format: Jung KH, Park JH, Sirupangi T, Jia D, Gandhi N, Pudakalakatti S, Elswood J, Porter W, Putluri N, Zhang XH-F, Chen X, Bhattacharya PK, Creighton CJ, Lewis MT, Rosen JM, Wong L-JC, Das GM, Osborne CK, Rimawi MF, Kaipparettu BA. Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-02-14.

Associations Between Drosophila suzukii (Diptera: Drosophilidae) and Fungi in Raspberries

The invasive vinegar fly, Drosophila suzukii Matsumura, has emerged as one of the most serious arthropod pests of primocane red raspberries (Rubus ideaus L.) in the United States. In raspberries, D. suzukii encounter a diverse community of microbes, including fruit rot pathogens such as Botrytis cinerea Pers and Cladosporium cladosporioides de Vries. In this study, our primary objectives were to evaluate D. suzukii-fungal associations and determine D. suzukii's influence on fungal communities in raspberry fruit. Through culture-based surveys of larval gut microbes, we isolated several yeast fungi (primarily Hanseniaspora spp.), as well as Cladosporium, Botrytis, and several other non-yeast fungi from larval frass, suggesting that D. suzukii larvae encounter and feed on these fungi. Subsequent field surveys confirmed that D. suzukii larvae occurred in berries affected by Botrytis fruit rot and Cladosporium fruit rot. Under laboratory conditions, D. suzukii may facilitate C. cladosporioides infections, likely through the introduction of epiphytic propagules on the fruit surface. We could not detect impacts on B. cinerea infections or establish a clear vectoring relationship for either fruit rot. These studies provide evidence for an association between D. suzukii and fungal fruit rot pathogens. Understanding interactions between raspberry fruit, D. suzukii, and fungal microbes-especially whether D. suzukii facilitates the development of fruit rots or conversely, if fruit rots influence D. suzukii infestation patterns-may improve pest and pathogen management programs.

Abstract P6-01-07: Mitochondria-nuclear communication regulates epithelial-mesenchymal transition and metastasis in triple negative breast cancer

For triple negative breast cancer (TNBC), the driver pathways are still poorly understood. Advances in cancer metabolism research over the last decade have enhanced and modified our understanding on Warburg effect. It is now known that mitochondria in tumors are not always defective in their ability to carry out oxidative phosphorylation. Instead, in proliferating cells, mitochondrial energy pathways are reprogrammed to meet the challenges of macromolecular synthesis and to escape from apoptosis. Tumor initiating cells (TICs) maintain cancer stem cell properties and are known to play significant role in TNBC metastasis. Mitochondrial retrograde regulation (MRR) is a bidirectional communication between mitochondria and nucleus. MRR is triggered by mitochondrial functional demands and it responds in a continuous manner to change metabolic needs of the cell. Using transmitochondrial cybrid (cybrid) technology, we generated different cybrid models under common nuclear backgrounds of benign breast epithelium or TNBC. Mitochondria from cells with different cancer potential such as benign breast epithelium, moderately metastatic and highly metastatic breast cancer cell lines were studied under the common nuclear background to understand MRR-regulated TIC properties and cancer pathways. Using genomic, metabolomic, and proteomic approaches, we confirmed the significance of mitochondrial character in the regulation of epithelial mesenchymal transition (EMT), TIC and metastatic properties. Altogether, our results suggest that MRR is critical in TNBC TIC character and stemness.

Citation Format: Park JH, Jung KH, Sirupangi T, Vithayathil S, Jin F, Putluri V, Piyarathna DWB, Yotnda P, Bhat VB, Sreekumar A, Lewis MT, Coarfa C, Putluri N, Creighton CJ, Wong L-JC, Kaipparettu BA. Mitochondria-nuclear communication regulates epithelial-mesenchymal transition and metastasis in triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-01-07.

Horticultural Production Systems Influence Ground Beetle (Coleoptera: Carabidae) Distribution and Diversity in Cucurbits

Commercial cucurbit production typically involves agriculturally intensive practices, with fields prepared using conventional tillage, plasticulture, and chemically based pest management. Conservation-based management options are limited. In this study, we consider two alternative strategies, strip tillage and the use of row covers. We compare their impact on the beneficial carabid beetle (Coleoptera: Carabidae) community in melons and squash, following conventional or organic systems, over two years. Multivariate analysis demonstrated that soil management system (strip tillage versus plasticulture) was the primary variable influencing carabid distribution; row cover was a less important factor. The response to soil management was species dependent. Some dominant species, such as Harpalus pensylvanicus DeGeer, demonstrated no preference for a particular soil treatment. For others, including the tiger beetle, Cicindela punctulata Olivier, and a slug predator, Chlaenius tricolor Dejean, activity-density was higher in strip-tillage production systems. Our analysis suggested that strip-tillage production systems support a richer, more diverse carabid community. These results demonstrate that even within intensive annual horticultural systems, production practices can play a critical role in shaping the beneficial arthropod community, potentially encouraging or limiting ecosystem services.

Abstract P2-06-11: Wild type N-Ras, overexpressed in basal-like breast cancer, promotes tumor formation by inducing IL8 secretion via JAK2 activation

"Basal-like" breast cancer (BLBC) is a very aggressive subtype of breast cancer. BLBC has very poor prognosis — median time to distant recurrence is just 2.6 years vs. 5 years overall, and survival time from diagnosis of distant metastatic disease is 9 months vs. 22 months. BLBC tumors usually do not express ER, Her2, or progesterone receptor. As such, they cannot be treated by the current targeted therapies, which target these molecules. What drive the formation and progression of BLBCs is largely unclear.

Ras GTPases are best known for mediating growth factor signaling. Oncogenic mutations in the RAS genes, K-RAS in particular, are found in more than 30% of human tumors. Surprisingly, oncogenic RAS mutations are rare in breast cancer. However, we found that wild-type N-RAS is overexpressed in BLBCs, possibly partly via promoter demethylation, but not in other breast cancer subtypes. Repressing N-RAS inhibits transformation and tumor growth, while overexpressing it enhances these processes even in preinvasive BLBC cells. In contrast, in breast cancer cells of other subtypes, repressing N-RAS expression does not affect growth and transforming activities. We identified N-Ras-responsive genes, most of which encode chemokines and cytokines, e.g., IL8. High expression levels of these N-Ras-responsive genes as well as of N-RAS itself in tumors correlate with poor patient outcome. N-Ras, but not K-Ras, induces IL8 by binding and activating the cytoplasmic pool of JAK2; IL8 then acts on both the cancer cells and stromal fibroblasts.

In conclusion, N-Ras drives BLBC by promoting transformation in epithelial cells, which may in turn remodel the tumor microenvironment to create a proinvasive state. Although oncogenic mutations affecting RAS are common in many other human cancers, tumorigenesis in an important subset of breast cancers is driven instead by increasing activity of wild-type N-Ras. Thus, to fully assess the impact of Ras on tumorigenesis, the role of wild-type as well as mutant Ras proteins must be carefully examined.

Citation Format: Zheng Z-Y, Bu W, Tian L, Fan C, Gao X, Zhang X, Yu C, Wang H, Liao Y-H, Li Y, Lewis MT, Edwards D, Zwaka TP, Hilsenbeck SG, Medina D, Perou CM, Creighton CJ, Zhang XH, Chang EC. Wild type N-Ras, overexpressed in basal-like breast cancer, promotes tumor formation by inducing IL8 secretion via JAK2 activation. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-06-11.

Abstract P2-02-07: Collection, high-resolution imaging, and single cell isolation of circulating tumor cells from patient derived xenograft models using the AccuCyte® – CyteFinder® system

Background: Patient-derived xenograft (PDX) models of human tumors offer many advantages over traditional cell line xenograft models and other mouse models of cancer. A PDX model may be used to randomize a given patient's tumor to multiple treatment regimens in order to predict treatment responses. When PDX models are grouped, they represent a clinical trial "cohort" for testing new therapies and identifying biomarkers of response. One such biomarker is circulating tumor cells (CTCs), which provide a window of the metastatic process. CTCs have been reported in several PDX models, further supporting their clinical relevance. Thus, PDX models may also be used to study the utility of CTC analysis to inform treatment decisions. However, most current CTC technologies intended for use with human samples cannot be used with the small blood volume from mice. The objective of our study was to adapt the AccuCyte® – CyteFinder® (AC-CF) system to detect CTCs from low volumes of mouse blood, and apply this method for the analysis of CTCs in a PDX model, including individual cell retrieval for molecular analysis. Methods: The AC-CF PDX process was modified to include a red blood cell lysis step instead of the density-based separation for the removal of red blood cells. The isolated cells were spread onto microscope slides using a stabilization solution, stained by multi-color immunofluorescence, and visualized by the CF high-resolution multi-channel fluorescence scanner. Automated image analysis identified CTCs, which was followed by single cell retrieval. For optimization of the assay, BT474 breast cancer cells were spiked into blood from a tumor-free control mouse ( approx. 500 cells in 250 µl). Slides with BT474 cells were used to test sensitivity by using antibodies against human cytokeratins (pan-CK), epithelial cell adhesion molecule (EpCAM), and erbB family growth factor receptors (EGFR and HER2) to detect the spiked-in cells. Assay specificity was tested by using antibodies specific for the mouse isoform of CD45. The antibody panel was tested on blood samples from 6 mice carrying small (300-400 mm3) tumors of the breast cancer PDX model (BCM-4888) previously published to have CTCs. Results: BT474 were identified by their large nuclei, positive staining with human specific antibodies against pan-CK, EpCAM, and EGFR/HER2 markers, and negative staining for mouse CD45. BT474 were detected in approximately the same amount as were spiked in. CTCs were identified in the blood of all 6 PDX mice tested. We found 1-6 CTCs per 330 µl of blood, and clusters of CTCs were also identified in 4 mice. Overall, these findings agree with published data on this PDX model. Single CTCs will be isolated using the CytePicker® retrieval module for single cell sequencing to confirm the human origin of these cells. These results along with ongoing work on additional PDX models will be presented at the meeting. Conclusion: The modified AC-CF process is a simple and sensitive method of analyzing small volumes of blood for CTC detection and isolation, features that are critical for the longitudinal analysis of CTCs in PDX models of cancer.

Citation Format: Ramirez AB, Sahay D, Lewis MT, Schiff R, Stilwell JL, Trivedi M, Kaldjian EP. Collection, high-resolution imaging, and single cell isolation of circulating tumor cells from patient derived xenograft models using the AccuCyte® – CyteFinder® system. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-07.

Drug-repositioning screening identified piperlongumine as a direct STAT3 inhibitor with potent activity against breast cancer

Signal transducer and activator of transcription (STAT) 3 regulates many cardinal features of cancer including cancer cell growth, apoptosis resistance, DNA damage response, metastasis, immune escape, tumor angiogenesis, the Warburg effect and oncogene addiction and has been validated as a drug target for cancer therapy. Several strategies have been used to identify agents that target Stat3 in breast cancer but none has yet entered into clinical use. We used a high-throughput fluorescence microscopy search strategy to identify compounds in a drug-repositioning library (Prestwick library) that block ligand-induced nuclear translocation of Stat3 and identified piperlongumine (PL), a natural product isolated from the fruit of the pepper Piper longum. PL inhibited Stat3 nuclear translocation, inhibited ligand-induced and constitutive Stat3 phosphorylation, and modulated expression of multiple Stat3-regulated genes. Surface plasmon resonance assay revealed that PL directly inhibited binding of Stat3 to its phosphotyrosyl peptide ligand. Phosphoprotein antibody array analysis revealed that PL does not modulate kinases known to activate Stat3 such as Janus kinases, Src kinase family members or receptor tyrosine kinases. PL inhibited anchorage-independent and anchorage-dependent growth of multiple breast cancer cell lines having increased pStat3 or total Stat3, and induced apoptosis. PL also inhibited mammosphere formation by tumor cells from patient-derived xenografts. PL's antitumorigenic function was causally linked to its Stat3-inhibitory effect. PL was non-toxic in mice up to a dose of 30 mg/kg/day for 14 days and caused regression of breast cancer cell line xenografts in nude mice. Thus, PL represents a promising new agent for rapid entry into the clinic for use in treating breast cancer, as well as other cancers in which Stat3 has a role.

A dosage-dependent pleiotropic role of Dicer in prostate cancer growth and metastasis

Dicer is as an RNase III enzyme essential for the maturation of the majority of microRNAs. Recent studies have revealed down-regulation or hemizygous loss of Dicer in many tumor models and demonstrated that suppressing Dicer activity enhances tumorigenic activities of lung and breast cancer cells, which support Dicer as a haploinsufficient tumor suppressor in these cancer models. Surprisingly, we found that knocking down Dicer expression suppresses the growth and tumorigenic capacity of human prostate cancer cell lines, but enhances migratory capacities of some prostate cancer cell lines. Dicer is up-regulated in human prostate cancer specimens, but lower Dicer expression portends a shorter time to recurrence. Complete ablation of Dicer activity in a Pten null mouse model for prostate cancer significantly halts tumor growth and progression, demonstrating that microRNAs play a critical role in maintaining cancer cell fitness. In comparison, hemizygous loss of Dicer in the same model also reduces primary tumor burden, but induces a more locally invasive phenotype and causes seminal vesicle obstruction at high penetrance. Disrupting Dicer activity leads to an increase in apoptosis and senescence in these models, presumably through up-regulation of P16/INK4a and P27/Kip1. Collectively, these results highlight a pleotropic role of Dicer in tumorigenesis that is not only dosage-dependent but also tissue context-dependent.

P4-04-02: Smoothened Function as a G-Protein Coupled Receptor in Mammary Epithelial Cells

Background

Hedgehog signaling orchestrates many key developmental processes, including cell fate determination and tissue patterning in the embryo, as well as tissue homeostasis and stem cell maintenance in the adult. Aberrant hedgehog signaling has been implicated in several cancers including skin, brain, prostate and breast. Previous work in our laboratory demonstrated that overexpression of activated Smoothened (SMO), a key effector in hedgehog signaling, leads to mammary hyperplasia, and is overexpressed in DCIS and IBCs.

Consistent with recent data, we now provide evidence that SMO signals via Gαi proteins in the mouse mammary gland.

Hypothesis: Smoothened promotes mammary gland proliferation by functioning as a G-protein coupled receptor(GPCR) and couples to one or more members of the PTX-sensitive Gαi family of heterotrimeric G-protein subunits.

Experimental Design and Methods: Expression of Gαi subunit(s) was tested by qRT-PCR & immunofluorescence microscopy of mammary epithelial cells (MECs) and whole mammary glands from SMO and WT mice. We analyzed mammary glands from single Gαi subunit null mice for developmental abnormalities. Genetic studies are underway in which SMO mice are crossed to Gαil2&3 null mice.

To elucidate downstream signaling events triggered by SMO activation, we are treating SMO derived MECs cultured in a 3D matrix and whole gland organ cultures with inhibitors of Gαi effector molecules and assessing proliferation status. We will also employ GTPγS binding assays using primary MECs from SMO overexpressing mice to test whether SMO can activate Gαi proteins in mammary gland epithelium.

Results and Discussion: Treatment of MMTV-Cre dependent SMO hyperplasias with pertussis toxin (PTX), a potent inhibitor of Gαi family of G-protein signaling, significantly attenuates mammary gland hyperproliferation. This result supports the hypothesis that Smoothened functions as a GPCR interacting with one or more members of the Gαi family.

We have now found that Gαi2 and Gαi3 null mice display an increased number of terminal end buds and a more completely filled fat pad relative to WT control littermates.

Our data suggest that SMO-expressing cells induce proliferation of neighboring WT cells and that low-level proliferation in SMO-expressing cells is not affected by PTX.

qPCR data indicates that Gαi1 is the most abundant transcript in sorted MECs which overexpress SMO and that the Notch signaling pathway may be activated.

While our mechanistic data thus far mostly comprises transcriptional analyses coupled with pharmacological inhibition, they offer insight as to which pathways may be regulated by SMO activation. Genetic crosses between the SMO and Gαi null mice should provide evidence that these two proteins interact in the developing mammary gland. When associated with biochemical data, these studies ought to provide functional insight into the mechanism behind SMO-driven mammary hyperplasias.

This work offers potential clinical implications towards breast cancer treatment as there exist therapeutic agents targeting the hedgehog signaling pathway in clinical trials that were developed by solely testing their ability to inhibit GLI1/2-mediated transcription. Our data identify targets for intervention other than the GLI transcription factors.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-04-02.

P4-04-01: Identification of a Unique Mammary Cell Type Expressing Mesenchymal Markers, but Capable of Multilineage Epithelial Differentiation

We have identified a previously uncharacterized cell population within the epithelial compartment of the post-pubertal mouse mammary gland. These cells can be found as singlets or as like pairs in both the cap and body cell layer of terminal end buds (TEB) of developing ducts, and are ultimately localized in a suprabasal position distributed throughout the mature mammary ductal tree. In differentiated ducts, these cells typically extend long processes that contact multiple surrounding luminal epithelial and myoepithelial cells suggesting a function in cell-cell communication. In younger animals, identified cells do not express epithelial markers including the major cytokeratins (CK) 5, 6, 8, and 14, or E-cadherin, nor do they express myoepithelial cell markers such as smooth muscle actin or p63. However, in 20 week old non-parous females, these cells can give rise to epithelial cell types expressing CK 5, 6, 8, or 14. In transplantation assays, epithelial fragment and whole mammary gland transplantation did not indicate a major role in regenerative growth of mammary ducts. Transplantation of dissociated epithelial cells and wound-healing assays are in progress. Taken together, these observations suggest that this unique cell population possess stem cell-like features in that they are capable of self-renewal, and of giving rise to all major differentiated cell types within the mouse mammary gland.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-04-01.

P4-07-03: Identification of Triple-Negative Primary Breast Cancer Xenograft Models with High Numbers of Circulating and Disseminated Tumor Cells

Background: Primary breast cancer xenografts, in which tumors are grown directly from patients and which maintain their original genotype and phenotype, have the potential to facilitate the study of tumor biology and progression. These models can also be instrumental in the discovery of novel therapeutic targets especially for the triple-negative (ER-, PR- and HER2−negative, TN) breast cancer. TN breast cancer is associated with high numbers of circulating and disseminated tumor cells (CTCs and DTCs), which predict poor outcome in patients and may play a role in tumor progression. However, isolation and detection of human CTCs and DTCs in these xenograft models have been challenging even with EpCAM-based enrichment methods. The goal of this study was to determine if CTCs and DTCs could be identified using human pan-CK staining in a panel of triple-negative primary breast cancer xenograft lines, which could then be employed to study the biology of these cells and to test novel therapies.

Methods: We screened 13 stable primary transplantable xenograft lines (1-6 mice per line), established by directly transplanting ethnically diverse triple-negative tumor samples into the epithelium-free mammary fat pads of SCID/Beige mice, for the presence of CTCs and DTCs. The triple-negative status was maintained in these xenograft lines over serial passages. To detect CTCs, peripheral blood mononuclear cells (PBMCs) were isolated from the blood collected from the inferior vena cava either by Ficoll gradient or RBC lysis, with a typical yield of 500,000 PBMCs in 500 μl of blood. Subsequently, PBMCs were immunostained for the presence of CTCs, which were defined as the cells positive for cytoplasmic human pan-cytokeratin staining and nuclear (DAPI/hematoxylin) counter stain. We also flushed the femurs and tibias of 7 xenograft lines to harvest bone marrow cells (BMCs) for the detection of DTCs using the same staining procedure. A xenograft line was considered positive for CTCs or DTCs if they were detected in at least 25% of mice. The presence of lung metastases was assessed in all the xenograft lines by histological examination.

Results: We detected CTCs (range: 1–128/20,000 PBMCs) in 6 out of 13 xenograft lines (46%) and DTCs (range: 1–21/20,000 BMCs) in 5 out of 7 (71%) lines. Interestingly, 4 of the 5 DTC-positive lines also had detectable CTCs. High numbers of CTCs (>20/20,000 PBMCs) were found in 3 xenograft lines, one of which also had high numbers of DTCs (>20/20,000 BMCs). No human pan-CK+ cells were detected in PBMCs and/or BMCs from 5 control mice without tumors. Among 13 xenograft lines, lung metastases were found in 5 lines (38%), of which 3 had detectable CTCs or DTCs. Of the 3 xenograft lines containing high CTCs and/or DTCs, 2 had lung metastases.

Conclusion: In summary, human pan-CK staining can effectively detect CTCs and DTCs in isolated PBMCs and BMCs of mice bearing triple-negative primary breast cancer xenografts. These xenograft lines with detectable CTCs and DTCs may represent a valuable preclinical model for detailed characterization of human CTCs and DTCs and for the discovery of new therapeutic targets for the triple-negative breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-03.

P5-21-01: A Renewable Tissue Resource of Phenotypically Stable Human Breast Cancer Xenografts for Preclinical Studies

Introduction Translational breast cancer research is hampered severely by difficulties in obtaining and studying primary human breast tissue, and by the lack of in vivo preclinical models that accurately reflect patient tumor biology. These limitations are due, in part, to the fact that traditional immunocompromised mouse models are not generally permissive for growth. We sought to circumvent some of these limitations by transplanting and growing human mammary tumors in the mammary fat pad of SCID/Beige immunocompromised mice in the absence of exogenous human fibroblasts.

Aims and Methods To establish a set of stable human breast cancer xenografts for preclinical studies. Human breast cancer biopsies were received, minced into small fragments and then transplanted directly into “cleared” fat pads of recipient SCID/Beige immunocompromised mice. Transplanted fat pads were checked weekly. After initial tumor was palpated and harvested, tumor fragments were transplanted into new SCID/Beige hosts for subsequent transplant generations. Serial immunohistochemical evaluations were performed to confirm human origin and biomarker status. Analytical flow cytometry for evaluating expression of proposed “cancer stem cell” markers, and gene and protein expression analysis were carried out on all stable lines.

Results and Conclusions Xenograft lines were established directly from breast cancer patient samples, without intervening culture in vitro, using the epithelium-free mammary fat pad as the transplantation site. Of the conditions tested, xenograft take rate was highest in the presence of a low-dose estradiol pellet without exogenous human fibroblasts. Thirty six stably transplantable xenograft lines representing 27 patients were established, using pre-treatment, mid-treatment, and/or post-treatment samples. Most patients yielding xenografts were “triple-negative” (ER-PR-HER2−) (n=21), we were able to establish lines from three ER-PR-HER2+ patients, one ER+PR+HER2−, one ER+PR-HER2−and one “triple-positive” (ER+PR+HER2+) patients. Serially passaged xenografts show phenotypic consistency with the tumor of origin at the histopathology level, and remarkable stability across multiple transplant generations at both the genomic, transcriptomic, and proteomic levels. Of 27 lines evaluated fully, thirteen xenografts showed metastasis to the mouse lung. These models thus serve as a renewable, quality-controlled tissue resource, and should prove useful for preclinical evaluation of experimental therapeutics.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-21-01.

P1-04-09: Biphasic Effects of Docetaxel and Hedgehog Signaling Antagonists on Breast Cancer Tumor-Initiating Cells In Vivo

Recent data suggest the existence of a subset of breast cancer cells variously termed cancer stem cells, tumor-initiating, or tumor-propagating cells, that are capable of self-renewal and of regenerating tumors upon transplantation that are biologically consistent with the tumor of origin. These cells appear to be intrinsically resistant to systemic chemo- and radiation therapies and may therefore be responsible for treatment resistance, and disease recurrence. Several signal transduction networks have been implicated in normal and malignant stem cell self-renewal. These include those of the Hedgehog, Notch, Wnt, EGF, FGF families of ligands. Antagonists of these networks have become attractive targeted therapeutic agents. In this study, we evaluated two different Hedgehog signaling antagonists, one targeting Smoothened (the main membrane effector of activated signaling) and one targeting GLI1/2 (the two transcription factors mediating ligand response), for their ability to shrink patient-derived xenograft tumors and to affect the number or function of breast tumor-initiating cells in vivo. Both antagonists showed little effect as single agents, but could augment tumor shrinkage by docetaxel. However, these effects were only observed in those models showing evidence of canonical SMO/GLI-mediated signaling. In dilutional transplantation assays, both SMO or GLI targeted agents have a biphasic effect on the behavior of the tumor-initiating population such that large cell numbers yielded few tumors while intermediate cell numbers yielded tumors at a comparable rate as controls. These data suggest that combination therapy alters the functional state of stem cells in the context of larger cell numbers rather than targeting the tumor-initiating cell directly. These data therefore have significant relevance for the interpretation of ongoing clinical trials of hedgehog signaling inhibitors in solid tumors, including breast cancer.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-04-09.

ES2-3: Patient-Derived Xenograft Models for Preclinical Breast Cancer Research: Not Just "Basal" Anymore

Translational breast cancer research is hampered by difficulties in obtaining and studying primary human breast tissue, and by the lack of in vivo preclinical models that reflect the range of patient tumor biology accurately. In an effort to overcome these limitations, several groups have recently succeeded in propagating patient-derived breast cancer xenografts representing multiple breast cancer subtypes, including estrogen and progesterone receptor positive, and HER2 positive tumors. In our laboratory, we have developed a diverse set of human breast tumors grown as xenografts in the mammary fat pad of SCID/Beige and NOD/SCID/IL2γ-receptor null (NSG) mice, two relatively new immunocompromised mouse models, under various transplant conditions. In all cases, xenograft lines were established directly from breast cancer patient samples, without intervening culture in vitro, using the epithelium-free mammary fat pad as the transplantation site. Of the conditions tested, xenograft take rate was highest in the presence of a low-dose estradiol pellet without exogenous human fibroblasts. Thirty five stably transplantable xenograft lines representing 27 patients were established, using pre-treatment, mid-treatment, and/or post-treatment samples. Most patients yielding xenografts were “triple-negative” (ER−PR-HER2−) (n=21). However, we were able to establish lines from three ER−PR-HER2+ patients, one ER+PR+HER2−, one ER+PR-HER2−, and one “triple-positive” (ER+PR+HER2+) patients. Serially passaged xenografts show phenotypic consistency with the tumor of origin at the histopathology level, and remarkable stability across multiple transplant generations at both the genomic, transcriptomic, and proteomic levels. Of 27 lines evaluated fully, thirteen xenografts showed metastasis to the mouse lung. These models, in conjunction with others like them, thus serve as renewable, quality-controlled tissue resources, and are proving useful for preclinical evaluation of experimental therapeutics.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr ES2-3.

P190A RhoGAP is required for mammary gland development

P190A and p190B Rho GTPase activating proteins (GAPs) are essential genes that have distinct, but overlapping roles in the developing nervous system. Previous studies from our laboratory demonstrated that p190B is required for mammary gland morphogenesis, and we hypothesized that p190A might have a distinct role in the developing mammary gland. To test this hypothesis, we examined mammary gland development in p190A-deficient mice. P190A expression was detected by in situ hybridization in the developing E14.5day embryonic mammary bud and within the ducts, terminal end buds (TEBs), and surrounding stroma of the developing virgin mammary gland. In contrast to previous results with p190B, examination of p190A heterozygous mammary glands demonstrated that p190A deficiency disrupted TEB morphology, but did not significantly delay ductal outgrowth indicating haploinsufficiency for TEB development. To examine the effects of homozygous deletion of p190A, embryonic mammary buds were rescued by transplantation into the cleared fat pads of SCID/Beige mice. Complete loss of p190A function inhibited ductal outgrowth in comparison to wildtype transplants (51% vs. 94% fat pad filled). In addition, the transplantation take rate of p190A deficient whole gland transplants from E18.5 embryos was significantly reduced compared to wildtype transplants (31% vs. 90%, respectively). These results suggest that p190A function in both the epithelium and stroma is required for mammary gland development. Immunostaining for p63 demonstrated that the myoepithelial cell layer is disrupted in the p190A deficient glands, which may result from the defective cell adhesion between the cap and body cell layers detected in the TEBs. The number of estrogen- and progesterone receptor-positive cells, as well as the expression levels of these receptors was increased in p190A deficient outgrowths. These data suggest that p190A is required in both the epithelial and stromal compartments for ductal outgrowth and that it may play a role in mammary epithelial cell differentiation.

Spinal upregulation of glutamate transporter GLT-1 by ceftriaxone: therapeutic efficacy in a range of experimental nervous system disorders

Glutamate neurotransmission is highly regulated, largely by glutamate transporters. In the spinal cord, the glutamate transporter GLT-1 is primarily responsible for glutamate clearance. Downregulation of GLT-1 can occur in activated astrocytes, and is associated with increased extracellular glutamate and neuroexcitation. Among other conditions, astrocyte activation occurs following repeated opioids and in models of chronic pain. If GLT-1 downregulation occurs in these states, GLT-1 could be a pharmacological target for improving opioid efficacy and controlling chronic pain. The present studies explored whether daily intrathecal treatment of rats with ceftriaxone, a beta-lactam antibiotic that upregulates GLT-1 expression, could prevent development of hyperalgesia and allodynia following repeated morphine, reverse pain arising from central or peripheral neuropathy, and reduce glial activation in these models. Ceftriaxone pre-treatment attenuated the development of hyperalgesia and allodynia in response to repeated morphine, and prevented associated astrocyte activation. In a model of multiple sclerosis (experimental autoimmune encephalomyelitis; EAE), ceftriaxone reversed tactile allodynia and halted the progression of motor weakness and paralysis. Similarly, ceftriaxone reversed tactile allodynia induced by chronic constriction nerve injury (CCI). EAE and CCI each significantly reduced the expression of membrane-bound, dimerized GLT-1 protein in lumbar spinal cord, an effect normalized by ceftriaxone. Lastly, ceftriaxone normalized CCI- and EAE-induced astrocyte activation in lumbar spinal cord. Together, these data indicate that increasing spinal GLT-1 expression attenuates opioid-induced paradoxical pain, alleviates neuropathic pain, and suppresses associated glial activation. GLT-1 therefore may be a therapeutic target that could improve available treatment options for patients with chronic pain.

Decreased TGFβ signaling and increased COX2 expression in high risk women with increased mammographic breast density

Abstract #1107

Background
 High mammographic density is associated with up to a 6-fold increased risk of breast cancer. Pathways responsible for this increased density are unknown. We hypothesize that specific molecular pathways exist that are associated with increased mammographic density and breast cancer risk, and may therefore be used to identify potential targets for chemoprevention.
 Methods
 Histologically confirmed normal breast tissue was collected from women undergoing breast surgery who had available demographic data and mammograms for review. Breast parenchymal density was classified according to the American College of Radiology's Breast Imaging – Reporting and Data System reporting system. Quantitative classification of mammographic parenchyma was performed using thresholding method and percent density. Women with low (less than 50%) versus high (greater than 50%) breast density were compared. Double-stranded cDNA was synthesized from the normal breast tissue using an oligo-dT primer containing a T7 RNA polymerase promoter, followed by in vitro transcription with biotinylated ribonucleotides. The labeled cRNA was hybridized to Affymetrix HG U133Plus2 chips which comprise ∼28,600 genes to determine gene expression patterns. Immunohistochemical analysis (IHC) of estrogen receptor, progesterone receptor, proliferation (Ki67) and COX2 expression was performed.
 Results
 Sixty-two women were identified, 26 (42%) had high, and 36 (58%) had low mammographic density. Neither age, menopausal nor hormone receptor status influenced the gene expression pattern. Seventy-three genes had differential expression between normal breast tissue with high and low mammographic density (p<0.001, fold change>1.5) and had a low false discovery rate (<10%). Of these 73 differentially expressed genes, network and canonical pathway analysis demonstrate decreased TGFβ signaling (TGFBR2, SOS, SMAD3 and CD44 expression) in dense breast relative to non-dense breast. By IHC, Ki67 (stroma) and COX2 expression were significantly higher in dense breasts (p<0.05) on univariate analysis, and only COX2 expression in the stroma was statistically significant at (p<0.01) on multivariate analysis.
 Conclusion
 TGFβ ligands are currently the only growth factors known to prevent mammary epithelial cell proliferation. TGFβ has been reported to influence COX-2 expression, and these molecules are highly differentially expressed in individuals at high risk of developing breast cancer. These results suggest that COX2 inhibition should be further investigated for breast cancer prevention despite possible increase in cardiovascular risk.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1107.

BRCA1 gene expression signature predicts for anthracycline-chemosensitivity in triple-negative breast cancer

Abstract #6039

Background: We used a previously published gene expression signature that can identify tumors from BRCA1 mutation carriers to evaluate its predictive value in triple-negative breast cancer as a marker for chemosensitivity to anthracycline-based chemotherapy. We proposed that based on preclinical evidence suggesting that BRCA1-deficient breast cancer cells are sensitive to DNA damaging drugs such as cisplatin and anthracyclines this gene expression profile may identify tumors with anthracycline chemosensitivity. Two previously published studies defined a gene expression signature associated with BRCA1 germline mutation.(1,2) In these studies, sporadic tumors were misclassified as BRCA1 tumors and further analysis revealed methylation of the BRCA1 promoter region and decreased BRCA1 gene expression. This finding suggests the possibility of identifying sporadic tumors with decreased BRCA1 activity.
 Methods: We selected from our database of a locally advanced breast cancer neoadjuvant trial all cases of triple negative breast cancer that received 4 cycles of doxorubicin/cyclophosphamide(AC, 60/200 mg/m2, every 3 weeks) prior to surgery. Pathologic response to chemotherapy was disappearance of all invasive cancer or microscopic residual disease. Tumoral gene expression profile previously obtained using Affymetrix U133A Chip was analyzed for an optimal set of 100 most differentially expressed genes distinguishing BRCA1 and sporadic triple negative tumors according to the previously identified gene signature by van't Veer et al.1 We performed unsupervised clustering to determine if this signature could classify a subtype of triple-negative tumors with "BRCAness" and to test our hypothesis that BRCA1-like tumors are more sensitive to AC. We then performed a supervised analysis to determine the most differentially expressed genes that could prospectively identify triple-negative sporadic tumors with “BRCAness” and tumors from BRCA1 germline carriers that are sensitive to anthracyclines.
 Results: Of the 66 patients enrolled in our neoadjuvant trial, 12 patient's tumors were triple negative and received preoperative AC. By unsupervised clustering, the gene expression pattern associated with BRCA1 cancers subdivided these sporadic cancers in to two groups: Group A(6/7 pathologic responders), and group B(5/5 non-pathologic responders). By supervised analysis, the most differentially overexpressed gene from the BRCA1 profile for AC sensitivity was YWHAH(14-3-3 eta polypeptide), while DKK3(Inhibitor of Wnt and Notch signaling pathway) and RPL23A were most overexpressed in all cases with adriamycin-resistance(p<0.01).
 Discussion: Triple negative sporadic breast cancer displaying “BRCAness” appear to be sensitive to AC chemotherapy. YWHAH, DKK3, and RPL23A are differentially expressed in anthracycline-sensitive versus resistant tumors. These three genes can potentially identify triple-negative breast cancers that exhibit “BRCAness” and sensitivity to DNA-damaging chemotherapy such as cisplatin, anthracycline, or PARP inhibitors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6039.

The hedgehog signaling network, mammary stem cells, and breast cancer: connections and controversies

Several signal transduction networks have been implicated in the regulation of mammary epithelial stem cell self-renewal and maintenance (Kalirai and Clarke 2006; Liu et al. 2005). These signaling networks include those of the Wnt, Notch, TGFO, EGF, FGF, IGF, and most recently, the Hedgehog (Hh) families of secreted ligands. However, we currently know very little about the cellular and molecular mechanisms by which these signaling pathways function to regulate normal epithelial stem/progenitor cells. What is clear is that the regulatory signaling networks thought to control normal stem/progenitor cell self-renewal and maintenance are, with the current sole exception of the hedgehog network, well-documented to have contributory roles in mammary cancer development and disease progression when misregulated. In this review, genetic regulation of mammary gland development by hedgehog network genes is outlined, highlighting a developing controversy as to whether activated hedgehog signaling regulates normal regenerative mammary epithelial stem cells or, indeed, whether activated hedgehog signaling functions at all in ductal development. In addition, the question of whether inappropriate hedgehog network activation influences breast cancer development is addressed, with emphasis on the prospects for using hedgehog signaling antagonists clinically for breast cancer treatment or prevention.

The Gli2 transcription factor is required for normal mouse mammary gland development

The hedgehog signal transduction network performs critical roles in mediating cell-cell interactions during embryogenesis and organogenesis. Loss-of-function or misexpression mutation of hedgehog network components can cause birth defects, skin cancer, and other tumors. The Gli gene family (Gli1, Gli2, and Gli3) encodes zinc finger transcription factors that act as mediators of hedgehog signal transduction. In this study, we investigate the role of Gli2 in mammary gland development. Mammary expression of Gli2 is developmentally regulated in a tissue compartment-specific manner. Expression is exclusively stromal during virgin stages of development but becomes both epithelial and stromal during pregnancy and lactation. The null phenotype with respect to both ductal and alveolar development was examined by transplantation rescue of embryonic mammary glands into physiologically normal host females. Glands derived from both wild type and null embryo donors showed ductal outgrowths that developed to equivalent extents in virgin hosts. However, in null transplants, ducts were frequently distended or irregularly shaped and showed a range of histological alterations similar to micropapillary ductal hyperplasias in the human breast. Alveolar development during pregnancy was not overtly affected by loss of Gli2 function. Ductal defects were not observed when homozygous null epithelium was transplanted into a wild type stromal background, indicating that Gli2 function is required primarily in the stroma for proper ductal development. DeltaGli2 heterozygotes also demonstrated an elevated frequency and severity of focal ductal dysplasia relative to that of wild type littermate- and age-matched control animals.

Antibacterial activity of 41 antimicrobials tested against over 2773 bacterial isolates from hospitalized patients with pneumonia: I--results from the SENTRY Antimicrobial Surveillance Program (North America, 1998)

Pneumonia is the second most frequent cause of nosocomial infection, and hospitalization frequently is needed for community-acquired pneumonia. Knowledge of causative pathogens through periodic surveillance, and their prevailing antimicrobial susceptibility patterns becomes paramount in choosing appropriate empiric therapy. The SENTRY Antimicrobial Surveillance Program, tracks pathogen distribution worldwide since 1997 and documents emerging resistance to a wide range of antimicrobial agents. During the respiratory disease season in 1998, each of 30 medical centers (25 in the United States [US], and five in Canada [CAN]) contributed 100 consecutive isolates obtained from hospitalized patients with suspected pneumonia. The 2773 organisms, processed by the monitor consisted of a total of 35 species, with Staphylococcus aureus comprising 25.6% of all isolates and five other species (Pseudomonas aeruginosa 18.7%, Haemophilus influenzae 9.4%, Streptococcus pneumoniae 7.8%, Klebsiella spp. 7.0%, and Enterobacter spp. 6.7%) making up almost 50% of the total. In the US, pneumococci (8.5%) were more prevalent than in CAN (4.1%; p = 0.001). The US isolates of S. pneumoniae were variably susceptible to penicillin (76.8%), with non-susceptible strains demonstrating greater levels of cross resistance to macrolides (31.8%), cefepime (9.0%) and cefotaxime (6.8%), but remaining susceptible to gatifloxacin and quinupristin/dalfopristin. H. influenzae and Moraxella catarrhalis were generally ampicillin-resistant, 40.4-44.4% and 93.7-95.7%, respectively. P. aeruginosa remained very susceptible to amikacin (91.3-93.8%) > tobramycin > meropenem > piperacillin/tazobactam > gentamicin > piperacillin > cefepime (80.0-81.8%). Extended spectrum beta-lactamase phenotypes among the Klebsiella spp. were isolated from five medical centers in the US and were 4.8-6.0% overall; a rate similar to the previous year. Among the US isolates of Enterobacter spp., only 77.6% and 79.6% were susceptible to ceftazidime and cefotaxime, respectively, but >90% were inhibited by cefepime, imipenem, meropenem, aminoglycosides, and fluoroquinolones. Isolates from CAN were generally more susceptible, except for Pseudomonas isolates, where resistance to aminoglycosides, fluoroquinolones and imipenem was greater. The SENTRY Program results outline important national differences in the frequencies of pathogen occurrence, but more importantly, identify unstable patterns of resistance to available antimicrobial drugs, and serves as a reference for results of other local, national or international investigations.

Hedgehog signaling in mouse mammary gland development and neoplasia

Genetic analyses of two hedgehog signal transduction network genes, Patched-1 and Gli2, has demonstrated a critical role for hedgehog signaling in mediating epithelial-stromal tissue interactions during ductal development. Disruption of either gene leads to similar, yet distinct, defects in ductal morphogenesis. Defects are mainly ductal dysplasias that closely resemble some hyperplasias of the human breast. Phenotypic analyses have been coupled with in situ hybridization, transplantation and tissue recombination analyses to formulate a model for tissue compartment-specific control of mouse mammary gland development by hedgehog signaling. In addition, the similarities among hedgehog mutation-induced ductal dysplasias and human breast pathologies suggest a role for altered hedgehog signaling in the development of mammary cancer.

Frequency of occurrence and antimicrobial susceptibility patterns for pathogens isolated from latin american patients with a diagnosis of pneumonia: results from the SENTRY antimicrobial surveillance program (1998)

The correct empiric choice of antimicrobial therapy in the treatment of pneumonia in hospitalized patients has established itself as a major therapeutic challenge to clinicians. Selection of an inappropriate antimicrobial agent could lead to increased rates of mortality and morbidity. Characteristics of pathogens responsible for this infection such as species prevalence, overall antimicrobial resistance rates, and mechanisms of detected resistance could serve as an invaluable resource to clinicians in making such therapeutic selections. This report addresses the aforementioned problems/needs by analysis of 712 strains isolated from the lower respiratory tract of patients hospitalized with a diagnosis of pneumonia in 10 Latin American medical centers in the SENTRY Antimicrobial Surveillance Program (1998). The four most frequently isolated pathogens (no/% of total) were: Pseudomonas aeruginosa (191/26.8%), Staphylococcus aureus (171/24.0%), Klebsiella spp. (86/12.1%), and Acinetobacter spp. (75/10.5%); representing nearly 75.0% of all isolates. More than 40 antimicrobial agents (23 reported) were tested against these isolates by reference broth microdilution methodology, and susceptibility profiles were established. The nonfermentative Gram-negative bacteria (P. aeruginosa and Acinetobacter spp.) exhibited high levels of resistance to the agents tested. Amikacin (77.5% susceptible) was the most active drug tested against P. aeruginosa 50.0% against the Acinetobacter spp. isolates. Based on published interpretive criteria, over 22.0% of the Klebsiella spp. and 12.5% of the Escherichia coli were classified as extended spectrum beta-lactamase (ESBL) producers. Of the cephalosporin class compounds tested against the Klebsiella spp. and E. coli isolates, cefepime demonstrated the highest rates of susceptibility (84.9% and 91.7%, respectively). This compound also fared well against the Enterobacter spp. isolates, inhibiting 88.2% of the isolates tested, many of which were resistant to ceftazidime and ceftriaxone. Resistance to oxacillin among the S. aureus isolates was nearly 50. 0%, with vancomycin, teicoplanin, and the streptogramin combination quinupristin/dalfopristin inhibiting all isolates. Several clusters of multiply resistant organisms were also observed, and further characterization by ribotyping and pulsed-field gel electrophoresis established possible patient-to-patient spread. The results of this study indicate that rates of resistance among respiratory tract pathogens continue to rise in Latin America, with specific concerns for the high prevalence of nonfermentative Gram-negative bacteria isolated, oxacillin resistance rates in S. aureus, and the epidemic dissemination of multiply-resistant strains in several medical centers. International surveillance programs (SENTRY) should assist in the control of escalating antimicrobial resistance in this geographic area.

Activity of macrolides, lincosamines, streptogramins and fluoroquinolones against streptococcus pneumoniae and enterococci isolates from the western hemisphere: example of international surveillance (SENTRY antimicrobial surveillance program )in the development of new drugs

Resistance among commonly isolated Gram-positive cocci have compromised the available therapeutic regimens and require structured monitoring at the local, regional, national, and international levels. Two popular treatment classes of antimicrobials (macrolides-lincosamines-streptogramins [MLS], fluoroquinolones) have been tested against 3, 049 isolates of Streptococcus pneumoniae and enterococci from the SENTRY Antimicrobial Surveillance program. The strains were obtained from clinical cases in hospitals in the United States, Canada, and six nations (10 medical centers )in Latin America. MLS and fluoroquinolone compounds had moderate activity against vancomycin-susceptible Enterococcus faecalis only (gatifloxacin, and trovafloxacin MIC(50), 0.5 microg/ml), and quinupristin/dalfopristin was potent only against E.faecium isolates (MIC(90), 1 microg/ml(-2) microg/ml). When tested against pneumococci, gatifloxacin, trovafloxacin, sparfloxacin, and quinupristin/dalfopristin (MIC(90), < or = 1 microg/ml)were most active among the newer drugs, but vancomycin and clindamycinn inhibited > or =99.8% and 84.7% to 99.1% of strains, respectively. These results from a global resistance monitoring program should encourage rapid drug development. Based on in vitro sensitivity testing, they indicate a promising role for the treatment of emerging resistant Gram-positive cocci. The clinical role for each new agent will depend on safety profiles, rates of administration, and other issues identified during development in the clinical trials process.

Homeobox genes in mammary gland development and neoplasia

Both normal development and neoplastic progression involve cellular transitions from one physiological state to another. Whereas much is being discovered about signal transduction networks involved in regulating these transitions, little progress has been made in identifying the higher order genetic determinants that establish and maintain mammary cell identity and dictate cell type-specific responses to mammotropic signals. Homeobox genes are a large superfamily of genes whose members function in establishing and maintaining cell fate and cell identity throughout embryonic development. Recent genetic and expression analyses strongly suggest that homeobox genes may perform similar functions at specific developmental transition points in the mammary gland. These analyses also suggest that homeobox genes may play a contributory or causal role in breast cancer.

In vitro evaluation of cefepime and other broad-spectrum beta-lactams against bacteria from Indonesian medical centers. The Indonesia Antimicrobial Resistance Study Group

The in vitro activity of cefepime and six other broad-spectrum beta-lactams (cefpirome, ceftazidime, ceftriaxone, imipenem, piperacillin/tazobactam (4 micrograms/mL fixed concentration), and oxacillin was evaluated against 191 isolates of clinical bacteria from Indonesia. Susceptibility testing was performed using Etest (AB BIODISK, Solna, Sweden) methodology. Isolates from 10 species groups were selected for analysis: Escherichia coli, Klebsiella spp., Enterobacter spp., indole-positive Proteae, Serratia spp., Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible staphylococci. The overall rank order of spectrum of activity was (% resistant): imipenem (2.2%) > cefepime (7.3%) > piperacillin/tazobactam > cefpirome > ceftazidime > ceftriaxone (16.2%). The "fourth-generation" cephalosporins, cefepime and cefpirome, displayed greater activity compared with the "third-generation" cephalosporins, ceftazidime, and ceftriaxone, against the 60 E. coli and Klebsiella spp. (30 each) isolates. Phenotypic extended spectrum beta-lactamase occurrence rates among the E. coli and Klebsiella spp. were 23.3 and 33.3%, respectively. Imipenem, cefepime, and cefpirome inhibited 95.7% of the 46 isolates of inducible Amp C cephalosporinase producing Enterobacteriaceae. The majority of the resistance observed to imipenem and cefepime among tested Indoneisian strains was attributable to the nonfermentative Gram-negative bacilli, P. aeruginosa and Acinetobacter spp. These results indicate the presence of beta-lactam resistance in Indonesia and the need for continued antimicrobial surveillance in this nation and region of the world, preferably using accurate quantitative methods.

In vitro evaluation of cefepime and other broad-spectrum beta-lactams for isolates in Malaysia and Singapore medical centers. The Malaysia/Singapore Antimicrobial Resistance Study Group

The degree of activity of several beta-lactam antimicrobial agents was assessed in Malaysia (four medical centers) and Singapore (two medical centers) tested against 570 clinical isolates. The organisms were tested locally by the Etest (AB BIODISK, Solna, Sweden) method, validated by concurrent use of quality assurance strains (94.1% accurate performance overall). Ten groups of bacteria were tested against cefepime, cefpirome, ceftazidime, ceftriaxone, piperacillin/tazobactam, oxacillin, and imipenem. Among the tested Escherichia coli and Klebsiella spp., the occurrence of extended spectrum beta-lactamase-producing phenotypes was 5.6-7.0% and 36.7-38.0%, respectively. These strains remained most susceptible (97.5-100.0%) to cefepime and imipenem. Ceftazidime-resistant Enterobacter spp. (21.4% resistant), Citrobacter spp. (15.0%), indole-positive Proteus spp. (6.0%), and Serratia spp. (9.7%) were not resistant to cefepime, and only one strain was resistant to imipenem. Imipenem was generally most potent against non-fermentative Gram-negative bacilli such as Acinetobacter spp. and Pseudomonas aeruginosa. All tested beta-lactams were active against the oxacillin-susceptible staphylococci, except ceftazidime (MIC90, 12 micrograms/mL; 63.2-84.8% susceptibility rates). Overall spectrums of activity (rank by % resistance) favored imipenem (3.5%) > cefepime (7.7%) > cefpirome (8.9%) > piperacillin/tazobactam (13.2%) > ceftriaxone (14.7%) > ceftazidime (16.9%). No significant differences in resistance patterns were noted between monitored nations, and these results indicate emerging, elevated rates of resistance versus the studied broad-spectrum beta-lactams in Malaysia and Singapore. Results provide benchmark data for future studies using quantitative methods to determine antimicrobial resistance in these geographic areas.

In vitro evaluation of broad-spectrum beta-lactams tested in medical centers in Korea: role of fourth-generation cephalosporins. The Korean Antimicrobial Resistance Study Group

Levels of resistance to the "third-generation" cephalosporins among isolates of clinical bacteria in Korea have been increasing at a rapid rate. This study evaluated the activity of cefepime, a "fourth-generation" cephalosporin, and six other broad-spectrum beta-lactam antimicrobials (cefpirome, ceftazidime, ceftriaxone, imipenem, piperacillin/tazobactam 4 micrograms/mL fixed concentration[, oxacillin) against 404 isolates of clinical bacteria from Korea. Susceptibility profiles of each isolate were established using the Etest (AB BIODISK, Solna, Sweden) method of susceptibility testing. Only the carbapenem imipenem was > 90% effective in inhibiting each of the species tested (Escherichia coli, Klebsiella, spp., Citrobacter spp., Enterobacter spp., indole-positive Proteae, Serratia spp., Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible staphylococci). Imipenem was followed by cefepime > cefpirome > piperacillin/tazobactam > ceftazidime > ceftriaxone in overall rank order of usable spectrum against the isolates tested. Extended spectrum beta-lactamase producing phenotypes were much more prevalent among the Klebsiella spp. (48.8%) than the E. coli (5.0%) isolates. Cefepime was much more active than cefpirome, 95.1% susceptible as compared with 70.7% susceptible, against the 41 isolates of Klebsiella spp. The results of this study corroborates findings from earlier studies with levels of resistance to the broad-spectrum beta-lactams in Korea continuing to rise indicating the need for intervention strategies.

In vitro evaluation of cefepime and other broad-spectrum beta-lactams in 22 medical centers in Japan: a phase II trial comparing two annual organism samples. The Japan Antimicrobial Resistance Study Group

An antimicrobial resistance surveillance study in Japan is presented representing the second year (Phase II) results from 22 medical centers. Each participant laboratory tested (Etest, AB BIODISK, Solna, Sweden) 100 organisms, 10 strains each from 10 species groups including Escherichia coli, Klebsiella spp., Enterobacter spp., Citrobacter spp., indole-positive Proteae, Serratia spp., Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible Staphylococcus aureus and coagulase-negative staphylococci. Generally only modest variations in the activity of the studied broad-spectrum beta-lactams was observed compared to the study a year before. Specifically, extended spectrum beta-lactamase (ESBL) rates in E. coli increased (2.9 to 8.1%), but the ESBL rate in Klebsiella spp. fell (8.6 to 5.0%). Overall the resistance to the beta-lactams varied from a 4.7% decrease (ceftazidime as a consequence of a modified staphylococcal breakpoint criteria) to a 1.0% increase (cefepime, not significant). The rank order of spectrums in 1998 only changed for cefoperazone-sulbactam (6.1% resistance) that was active against more strains than cefpirome (6.8% resistance). The overall spectrum rank order for the 1998 Japan sample (% resistance) was: cefepime (3.2%) > imipenem (4.1%) > cefoperazone-sulbactam (6.1%) > cefpirome (6.8%) > ceftazidime (8.4%) > piperacillin (19.9%). As with a similar study in 1997, imipenem-resistant isolates of P. aeruginosa and Serratia spp. were discovered with metalloenzymes, usually found in the same medical centers. These results demonstrate the continued in vitro activity and potential sustained clinical efficacy of several broad-spectrum beta-lactams in Japan. Rapid emergence of new or novel resistance were not wide spread using a precise quantitative MIC system. Continued surveillance in this nation would be prudent to document the activity of this clinically valuable class of safe, antimicrobial agents.

Defects in mouse mammary gland development caused by conditional haploinsufficiency of Patched-1

In vertebrates, the hedgehog family of cell signaling proteins and associated downstream network components play an essential role in mediating tissue interactions during development and organogenesis. Loss-of-function or misexpression mutation of hedgehog network components can cause birth defects, skin cancer and other tumors. The mammary gland is a specialized skin derivative requiring epithelial-epithelial and epithelial-stromal tissue interactions similar to those required for development of other organs, where these interactions are often controlled by hedgehog signaling. We have investigated the role of the Patched-1 (Ptc1) hedgehog receptor gene in mammary development and neoplasia. Haploinsufficiency at the Ptc1 locus results in severe histological defects in ductal structure, and minor morphological changes in terminal end buds in heterozygous postpubescent virgin animals. Defects are mainly ductal hyperplasias and dysplasias characterized by multilayered ductal walls and dissociated cells impacting ductal lumens. This phenotype is 100% penetrant. Remarkably, defects are reverted during late pregnancy and lactation but return upon involution and gland remodeling. Whole mammary gland transplants into athymic mice demonstrates that the observed dysplasias reflect an intrisic developmental defect within the gland. However, Ptc1-induced epithelial dysplasias are not stable upon transplantation into a wild-type epithelium-free fat pad, suggesting stromal (or epithelial and stromal) function of Ptc1. Mammary expression of Ptc1 mRNA is both epithelial and stromal and is developmentally regulated. Phenotypic reversion correlates with developmentally regulated and enhanced expression of Indian hedgehog (Ihh) during pregnancy and lactation. Data demonstrate a critical mammary role for at least one component of the hedgehog signaling network and suggest that Ihh is the primary hedgehog gene active in the gland.

Evaluation of the in vitro activity of six broad-spectrum beta-lactam antimicrobial agents tested against over 2,000 clinical isolates from 22 medical centers in Japan. Japan Antimicrobial Resistance Study Group

Numerous broad-spectrum beta-lactam antimicrobial agents have been introduced into medical practice since 1985. Although several of these compounds have advanced, infectious disease therapy resistances to them has also emerged world-wide. In 1997, a Japanese 22 medical center investigation was initiated to assess the continued utility of these agents (oxacillin or piperacillin, ceftazidime, cefepime, cefpirome, cefoperazone/sulbactam [C/S], imipenem). The participating medical centers represented a wide geographic distribution, and a common protocol and reagents were applied. Three control strains and a set of challenge organisms were provided to participant centers. Etest (AB BIODISK, Solna, Sweden) strips were used in concurrent tests of these organisms and a qualitative determination of participant skills in the identification of resistant and susceptible phenotypes was established. The quantitative controls demonstrated 97.7-99.2% of MIC values within established QC limits, and the qualitative (susceptibility category) controls documented a 97.3% agreement of participant results with that of reference values (1,320 total results). Only 0.2% of values were false-susceptible errors. After the participant quality was assured, a total of 2,015 clinical strains were tested (10 strains from 10 different organism groups including methicillin-susceptible Staphylococcus aureus and coagulase-negative staphylococci [CoNS], Escherichia coli, Klebsiella spp., Citrobacter freundii, Enterobacter spp., indole-positive Proteae, Serratia spp., Acinetobacter spp., and Pseudomonas aeruginosa). The staphylococci were uniformly susceptible to all drugs tested except ceftazidime (MIC90, 24 micrograms/ml) that had a potency six- to 12-fold less than either cefepime or cefpirome. Only 3.7 and 45.1% of S. aureus and CoNS were susceptible to ceftazidime, respectively. Among E. coli and Klebsiella spp. the rank order of antimicrobial spectrum was imipenem = "fourth-generation" cephalosporins > ceftazidime > C/S > piperacillin. Possible extended spectrum beta-lactamase phenotypes were identified in 2.9-8.6% of these isolates. Isolates of C. freundii, Enterobacter spp., Proteae, and Serratia spp. that were resistant to ceftazidime and piperacillin remained susceptible to imipenem (0.0-4.5% resistance) and cefepime (0.0-5.0%). Acinetobacters were inhibited best by C/S (99.5% susceptible) and least susceptible to piperacillin (MIC90, > 256 micrograms/ml; 21.7% susceptible) activity. P. aeruginosa isolates were most susceptible to cefepime (83.6%) and this zwitterionic cephalosporin also had the lowest level of resistance (9.1% of MICs at > or = 32 micrograms/ml). Several multi-resistant organisms were identified in participant medical centers including S. marcescens strains resistant to cefepime, imipenem, or both observed in six hospitals. Clonal spread was documented in two medical centers; one hospital having two distinct epidemic clusters. Also a multi-resistant E. cloacae was found in two patients in the same hospital. Evaluations of carbapenem resistance in four species discovered only two strains (in same hospital) among 40 P. aeruginosa isolates (5.0%) with a metallo-enzyme, with nearly all of the remaining strains inhibited by an Ambler Class C enzyme inhibitor (BRL42715) indicating a hyperproduction of a chromosomal cephalosporinase. These results indicate that most newer beta-lactams remain widely useable in medical centers in Japan, but emerging often clonal, resistances have occurred. The overall rank order of antimicrobial spectrum against all ten tested bacterial groups favors the "fourth-generation" cephalosporin, cefepime (96.4% susceptible) as an equal to imipenem (95.9%) > C/S (90.9%) = cefpirome (90.0%) > ceftazidime (75.1%) = penicillins, either oxacillin or piperacillin (76.4%).

Regulated expression patterns of IRX-2, an Iroquois-class homeobox gene, in the human breast

In the mouse mammary gland, homeobox gene expression patterns suggest roles in development and neoplasia. In the human breast, we now identify a family of Iroquois-class (IRX) homeobox genes. One gene, IRX-2, is expressed in discrete epithelial cell lineages being found in ductal and lobular epithelium, but not in myoepithelium. Expression is absent from associated mesenchymal adipose stroma. During gland development, expression is concentrated in terminal end buds and terminal lobules and is reduced in a subset of epithelial cells during lactation. In contrast to observations for many homeobox genes in the mouse mammary gland in which homeobox gene expression is lost on neoplastic progression, IRX-2 expression is maintained in human mammary neoplasias. Data suggest IRX-2 functions in epithelial cell differentiation and demonstrate regulated expression during ductal and lobular proliferation as well as lactation.

Comparative in vitro evaluation of dirithromycin tested against recent clinical isolates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae, including effects of medium supplements and test conditions on MIC results

The use of macrolides for treatment of respiratory complaints has been complicated by susceptibility test conditions that adversely effect the in vitro test results and perceived potencies of these compounds. Dirithromycin was studied as to its in vitro activity compared to other macrolides as well as the effects that environmental incubation variations and inoculum concentrations may have on susceptibility results. Dirithromycin was less active than other macrolides tested (azithromycin clarithromycin, erythromycin) against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis with MIC90 values of 16, 32, and 1 microgram/ml, respectively; an activity that was most similar to roxithromycin. This reduced activity may be compensated by the superior pharmacokinetic properties that dirithromycin possesses compared to other members in its class. Method variation studies show that incubation in CO2 environments increase the MIC values for all macrolide compounds and dirithromycin was most effected by pH changes in three in vitro methods tested (Etest [AB BIODISK, Solna, Sweden] broth microdilution, and disk diffusion). Variations in inoculum concentration had minimal effect on dirithromycin potency. In addition the variability (lack of reproducibility) of the test results with dirithromycin were not significant. Dirithromycin is an alternative therapeutic choice among macrolide compounds for treatment of community-acquired respiratory infections caused by various streptococci, Legionella pneumophilia, Mycoplasma pneumoniae and M. catarrhalis, and also possesses a modest in vitro potency versus H. influenzae coupled with excellent pharmacokinetic properties. In vitro tests with dirithromycin will continue to be problematic for H. influenzae because of the adverse effects of recommended CO2 incubation for some standardized methods or commercial products (Etest).

Decreased vascular endothelial growth factor expression associated with tumor regression induced by (E)-2'-deoxy-2'-(fluoromethylene)cytidine (MDL 101,731)

The effect of the antitumor drug MDL 101,731 [(E)-2'-deoxy-2'-(fluoromethylene)cytidine] on tumor growth and on steady-state vascular endothelial growth factor (VEGF) mRNA levels in MDA-MB-231, PC-3, MCF-7, and HT-29 human tumor xenografts grown in nude mice was examined, using quantitative in situ hybridization. MDL 101,731 caused regression of MDA-MB-231 and PC-3 tumor xenografts, but only inhibition of growth (without regression) of MCF-7 xenografts. The drug caused inhibition of growth of HT-29 xenografts at low doses, and regression at high doses. When treatment with MDL 101,731 led to tumor regression, VEGF mRNA levels were decreased. When treatment led only to inhibition of growth, there was no significant change in VEGF mRNA. Further examination of the tumor xenografts revealed that elevated VEGF mRNA was associated with hypoxic zones surrounding areas of necrosis in the tumors, and that the drop in VEGF mRNA observed in tumors from mice treated with MDL 101,731 correlated with a loss of zones of necrosis. In contrast, treatment with cisplatin led to either an increase (PC-3) or no change (MDA-MB-231) in VEGF mRNA levels, and no loss of necrotic zones. Quantitative analysis of changes in VEGF mRNA levels was supported by immunohistochemical analysis of VEGF protein in the same tumor specimens. In vitro, MDL 101,731 was a potent inhibitor of VEGF secretion in cells exposed to hypoxia, whereas there was no effect of cisplatin on VEGF secretion by three of the four cell lines tested. These findings suggest that inhibition of VEGF expression by MDL 101,731 may distinguish this compound from other classes of cytotoxic agents, such as cisplatin.

Analysis of frequency (frq) clock gene homologs: evidence for a helix-turn-helix transcription factor

The frq gene plays a key role in the organization of the Neurospora crassa circadian clock. Our previous analysis of a C-terminal fragment of the putative FRQ protein suggested it is a nuclear transcription factor but did not identify a known DNA-binding domain. If the hypothesis is correct that FRQ is a transcription factor, sequences consistent with this function should be conserved in distantly related species. To investigate, we have cloned frq homologs from other filamentous fungi including Chromocrea spinulosa, and Leptosphaeria australiensis. Alignment of the Leptosphaeria and Chromocrea proteins with the published (complete) sequences for Neurospora crassa and Sordaria fimicola shows that they are respectively about 47%, and 43%, identical to both Neurospora and Sordaria. The alignment identifies several short regions of high conservation punctuated by regions showing near total divergence. Sequences consistent with FRQ being a transcription factor are generally conserved. Most importantly, we show that a highly conserved segment of the protein has strongly predicted helix-turn-helix (HTH) structure as supported by three independent methods. Further, this segment shows the defining sequence characteristics of known HTH DNA-binding domains. Amino acids at positions altered in frq mutant alleles are conserved in all species examined. Transformation of the Neurospora frq9 (conditionally arrhythmic) mutant with the Chromocrea homolog rescued the pigmentation and conidiation defects of the mutant but not the circadian defect; the Leptosphaeria homolog failed to rescue any defect. Together, these data provide the first testable hypotheses concerning several specific aspects of FRQ structure and function.

Evolution of the frequency (frq) clock locus in Ascomycete fungi

The frequency (frq) locus of Neurospora crassa plays a key role in the organization of circadian rhythms. Similar timing systems have been found in nearly all eukaryotes as well as some prokaryotes; thus, frq may be an excellent gene with which to conduct evolutionary studies. To investigate, we used the cloned frq locus from ascomycete fungi representing two classical taxonomic classes and three orders to examine two open questions in ascomycete evolution. Class Pyrenomycetidae is represented by several species of Neurospora, Sordaria fimicola, and Chromocrea spinulosa; class Loculoascomycetidae is represented by the marine fungus Leptosphaeria australiensis. Generation of detailed restriction maps of homologs from the Neurospora species allows analysis of evolutionary relationships among these closely related species. A maximum-parsimony tree based on these restriction data suggests that Neurospora tetrasperma groups more closely with Neurospora sitophila than with Neurospora crassa using the homothallic species Neurospora galapagosensis as an outgroup. A maximum-parsimony tree derived using amino acid sequences from Neurospora crassa, Sordaria fimicola, Chromocrea spinulosa, and Leptosphaeria australiensis surprisingly suggests that Leptosphaeria austral should be classified within Pyrenomycetes rather than in a separate class. This suggestion is based on the observations that Leptosphaeria groups with Chromocrea on an evolutionary tree, is more closely related to Neurospora and Sordaria than is Chromocrea, and shares a conserved intron with Chromocrea. Together, these data show that frq is a useful gene with which to conduct evolutionary studies.

Response of human colon and prostate tumor xenografts to (E)-2'-deoxy-2'-(fluoromethylene) cytidine, an inhibitor of ribonucleotide reductase

Daily oral or intravenous administration of the ribonucleoside diphosphate reductase inhibitor, (E)-2'-deoxy-2'-(fluoromethylene)cytidine (MDL 101,731), to nude mice caused rapid regression of colon and prostate xenografts. Studies were performed to optimize dosing schedule and route of administration. MDL 101,731 was tested against colon (HT-29) and prostate (PC-3) xenografts using twice weekly oral and intravenous administration. PC-3 tumors regressed almost completely with doses of 20 mg/kg. HT-29 xenografts regressed during intravenous administration of 100 mg/kg MDL 101,731, whereas oral administration was less effective. Based on these data it seems that MDL 101,731 is effective when administered intravenously, twice weekly and is an excellent candidate for clinical development against solid tumors.

Relaxing retinotomies and retinectomies. Surgical results and predictors of visual outcome

Functional and anatomic success after relaxing retinotomy may be limited by recurrent retinal detachment or severe hypotony. Fifty-four consecutive eyes undergoing relaxing retinotomy for proliferative vitreoretinopathy (42 eyes) and trauma (12 eyes) were analyzed to determine whether perioperative factors, including size and location of the retinotomy, influenced visual or anatomic outcome. After 6 months' minimum follow-up, anatomic success (retina attached posterior to buckle and an intraocular pressure of 3 mm Hg or more) was achieved in 35 eyes (64%). Functional success (visual acuity of 5/200 or better) was achieved in 14 eyes (26%). Factors predicting functional success by stepwise logistic regression analysis included a preoperative visual acuity of hand motions or better and location of the retinotomy in the superior four clock hours of the fundus. Causes of anatomic failure included proliferative vitreoretinopathy (11 eyes) and severe hypotony or phthisis (8 eyes). Superior location of the retinotomy and visual acuity of hand motions or better favorably influenced visual outcome after relaxing retinotomy.

Striking sequence similarity among sialic acid-binding lectin, pancreatic ribonucleases, and angiogenin: possible structural and functional relationships

We found that a sialic acid-binding lectin (SABL) from bullfrog egg bears a remarkable degree of similarity with human angiogenin and the pancreatic ribonucleases (EC 3.1.27.5). Based on (1) the conservation of several disulfide bond-forming cysteines, (2) a cluster of nonpolar residues, and (3) a number of active-site residues of bovine ribonuclease, we propose that SABL has essentially the same secondary and tertiary structures and very likely has ribonuclease activity. Other possible physiological roles are discussed.

Leukotriene D4 and E4 formation by plasma membrane bound enzymes

The homogenate of rat basophilic leukemia cells produces both the dihydroxy-leukotrienes and the peptido-leukotrienes (LT) C4, D4 and E4. The enzymes responsible for the formation of LTA4 and LTB4 are in the soluble fraction while the enzymes for LTC4, LTD4 and LTE4 are particulate (10,000 X g pellet). Centrifugation of the 10,000 X g pellet over a sucrose gradient resulted in two subfractions, a membrane fraction and a pellet (sucrose pellet). The fractions were incubated with LTC4, and the products were identified by bioassay, HPLC and UV spectra. The membrane fraction contained the enzymes gamma-glutamyl transpeptidase and amino peptidase which convert LTC4 to LTD4 and LTD4 to LTE4, respectively. When incubated with LTC4, the membrane fraction showed a dose dependent formation of LTD4 and a time course which reached a plateau at 30 to 45 minutes. Addition of serine.borate blocked the formation of LTD4, and cysteine blocked LTE4 production. The sucrose pellet showed little conversion of LTC4 to LTD4. We conclude that the gamma-glutamyl transpeptidase and the amino peptidase which produce LTD4 and LTE4 respectively are plasma membrane bound.