Cell state dependent effects of Bmal1 on melanoma immunity and tumorigenicity

The circadian clock regulator Bmal1 modulates tumorigenesis, but its reported effects are inconsistent. Here, we show that Bmal1 has a context-dependent role in mouse melanoma tumor growth. Loss of Bmal1 in YUMM2.1 or B16-F10 melanoma cells eliminates clock function and diminishes hypoxic gene expression and tumorigenesis, which could be rescued by ectopic expression of HIF1α in YUMM2.1 cells. By contrast, over-expressed wild-type or a transcriptionally inactive mutant Bmal1 non-canonically sequester myosin heavy chain 9 (Myh9) to increase MRTF-SRF activity and AP-1 transcriptional signature, and shift YUMM2.1 cells from a Sox10high to a Sox9high immune resistant, mesenchymal cell state that is found in human melanomas. Our work describes a link between Bmal1, Myh9, mouse melanoma cell plasticity, and tumor immunity. This connection may underlie cancer therapeutic resistance and underpin the link between the circadian clock, MRTF-SRF and the cytoskeleton.

Age-related increases in IGFBP2 increase melanoma cell invasion and lipid synthesis

Aged melanoma patients (>65 years old) have more aggressive disease relative to young patients (<55 years old) for reasons that are not completely understood. Analysis of the young and aged secretome from human dermal fibroblasts identified >5-fold levels of insulin-like growth factor binding protein 2 (IGFBP2) in the aged fibroblast secretome. IGFBP2 functionally triggers upregulation of the PI3K-dependent fatty acid biosynthesis program in melanoma cells through increases in FASN. Melanoma cells co-cultured with aged dermal fibroblasts have higher levels of lipids relative to young dermal fibroblasts, which can be lowered by silencing IGFBP2 expression in fibroblasts, prior to treating with conditioned media. Conversely, ectopically treating melanoma cells with recombinant IGFBP2 in the presence of conditioned media from young fibroblasts, promoted lipid synthesis and accumulation in the melanoma cells. Neutralizing IGFBP2 in vitro reduces migration and invasion in melanoma cells, and in vivo studies demonstrate that neutralizing IGFBP2 in syngeneic aged mice, ablates tumor growth as well as metastasis. Conversely, ectopic treatment of young mice with IGFBP2 in young mice increases tumor growth and metastasis. Our data reveal that aged dermal fibroblasts increase melanoma cell aggressiveness through increased secretion of IGFBP2, stressing the importance of considering age when designing studies and treatment.

Significance

The aged microenvironment drives metastasis in melanoma cells. This study reports that IGFBP2 secretion by aged fibroblasts induces FASN in melanoma cells and drives metastasis. Neutralizing IGFBP2 decreases melanoma tumor growth and metastasis.

Use of physiologically‐based pharmacokinetic modeling to inform dosing of the opioid analgesics fentanyl and methadone in children with obesity

Obesity is an increasingly alarming public health threat, with nearly 20% of children classified as obese in the United States today. Children with obesity are commonly prescribed the opioids fentanyl and methadone, and accurate dosing is critical to reducing the risk of serious adverse events associated with overexposure. However, pharmacokinetic studies in children with obesity are challenging to conduct, so there is limited information to guide fentanyl and methadone dosing in these children. To address this clinical knowledge gap, physiologically‐based pharmacokinetic models of fentanyl and methadone were developed in adults and scaled to children with and without obesity to explore the interplay of obesity, age, and pharmacogenomics. These models included key obesity‐induced changes in physiology and pharmacogenomic effects. Model predictions captured observed concentrations in children with obesity well, with an overall average fold error of 0.72 and 1.08 for fentanyl and methadone, respectively. Model simulations support a reduced fentanyl dose (1 vs. 2 μg/kg/h) starting at an earlier age (6 years) in virtual children with obesity, highlighting the importance of considering both age and obesity status when selecting an infusion rate most likely to achieve steady‐state concentrations within the target range. Methadone dosing simulations highlight the importance of considering genotype in addition to obesity status when possible, as cytochrome P450 (CYP)2B6*6/*6 virtual children with obesity required half the dose to match the exposure of wildtype children without obesity. This physiologically‐based pharmacokinetic modeling approach can be applied to explore dosing of other critical drugs in children with obesity.

Abstract 5086: The aged tumor microenvironment promotes melanoma metabolic plasticity and therapy

“Aged” melanoma patients (&gt;55 years old) have poorer prognosis and reduced response rates to targeted therapy relative to “young” patients (&lt;40 years old). Here, we report an altered metabolic landscape in the aged tumor microenvironment (TME) as critical for melanoma aggressiveness. Aged fibroblasts uptake high levels of glucose compared to their young counterparts, which fuels lipid production. Melanoma cells cultured in an aged TME in vitro or in vivo display elevated intracellular lipid levels and increased metastatic potential relative to melanoma cells in a young TME. Further, lipidomics reveal an elevated lipid profile (i.e., triglycerides, ceramides, and cholesterol) preferentially secreted by aged fibroblasts relative to young. In turn, we show that melanoma cells adaptively increase extracellular fatty acid scavenging via the lipid transporter FATP2 in the lipid rich aged TME. Melanoma cells cultured in the aged TME also display an increased oxygen consumption rate (OCR) relative to those grown in young TME, which could be ablated when fatty acid transport into the mitochondria is blocked with etomixir. Notably, melanoma cells in the aged TME treated with BRAFi/MEKi in combination with a FATP2 inhibitor display decreased OCR relative to BRAFi/MEKi inhibitor alone, which paralleled the increased overall survival of aged mice treated with BRAFi/MEKi/FATP2i relative to either agent alone. To rule out off-target effects of the FATP2 inhibitor, we used a doxycycline inducible system for FATP2 knockdown in melanoma cells and reproduced the abrogation of tumor growth and extension of survival in aged immune-competent mice when combined with BRAFi/MEK therapy. Additionally, elevated FATP2 levels correlate with worse response in human patients. We hypothesize the aged TME triggers adaptive metabolic plasticity of melanoma cells critical for therapy escape.

Citation Format: Gretchen Marie Alicea, Vito W. Rebecca, Aaron Goldman, Mitchell Fane, Reeti Behera, Marie Webster, Brett Ecker, Ian Blair, David Speicher, Zachary Schug, Ashani Weeraratna. The aged tumor microenvironment promotes melanoma metabolic plasticity and therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5086.

Population Pharmacokinetics of Milrinone in Infants, Children, and Adolescents

Milrinone is a type 3 phosphodiesterase inhibitor used to improve cardiac output in critically ill infants and children. Milrinone is primarily excreted unchanged in the urine, raising concerns for toxic accumulation in the setting of renal dysfunction of critical illness. We developed a population pharmacokinetic model of milrinone using nonlinear mixed-effects modeling in NONMEM to perform dose-exposure simulations in children with variable renal function. We included children aged <21 years who received intravenous milrinone per clinical care. Plasma milrinone concentrations were measured using a validated liquid chromatography-tandem mass spectrometry assay (range 1-5000 ng/mL). We performed dose-exposure simulations targeting steady-state therapeutic concentrations of 100-300 ng/mL previously established in adults and children with cardiac dysfunction. We simulated concentrations over 48 hours in typical subjects with decreasing creatinine clearance (CrCl), estimated using the updated bedside Schwartz equation. Seventy-four patients contributed 111 plasma samples (concentration range, 4-634 ng/mL). The median (range) postmenstrual age (PMA) was 3.7 years (0-18), and median weight (WT) was 13.1 kg (2.6-157.7). The median serum creatinine and CrCl were 0.5 mg/dL (0.1-3.1) and 117.2 mL/min/1.73 m2 (13.1-261.3), respectively. A 1-compartment model characterized the pharmacokinetic data well. The final model parameterization was: Clearance (L/h) = 15.9*(WT [kg] / 70)0.75 * (PMA1.12 / (67.71.12 +PMA1.12 )*(CrCl / 117)0.522 ; and Volume of Distribution (L) = 32.2*(WT [kg] / 70). A loading dose of 50 µg/kg followed by a continuous infusion of 0.5 µg/kg/min resulted in therapeutic concentrations, except when CrCl was severely impaired at ≤30 mL/min/1.73 m2 . In this setting, a 25 µg/kg loading dose and 0.25 µg/kg/min continuous infusion resulted in therapeutic exposures.

Immunogenicity and Safety of a Measles-Mumps-Rubella Vaccine Administered as a First Dose to Children Aged 12 to 15 Months: A Phase III, Randomized, Noninferiority, Lot-to-Lot Consistency Study

BACKGROUND

MMR II (M-M-R II [Merck & Co, Inc.]) is currently the only measles, mumps, and rubella (MMR) vaccine licensed in the United States. A second MMR vaccine would mitigate the potential risk of vaccine supply shortage or delay. In this study, we assessed the immunogenicity and safety of another MMR vaccine (MMR-RIT [Priorix, GlaxoSmithKline]) compared with those of the MMR II in 12- to 15-month-old children who received it as a first dose.

METHODS

In this phase III, observer-blinded, noninferiority, lot-to-lot consistency clinical trial (ClinicalTrials.gov identifier NCT01702428), 5003 healthy children were randomly assigned to receive 1 dose of MMR-RIT (1 of 3 production lots) or MMR II along with other age-recommended routine vaccines. We evaluated the immunogenicity of all vaccines in terms of antibody concentrations (by using an enzyme-linked immunosorbent assay or electrochemiluminescence assay) and/or seroresponse rates 43 days after vaccination. We also assessed the reactogenicity and safety of the vaccines.

RESULTS

Immunoresponses after vaccination with MMR-RIT were robust and noninferior to those after vaccination with the MMR II. Immunogenicity of the 3 production lots of MMR-RIT was consistent; more than 97% of the children had a seroresponse to MMR components. The coadministered vaccines elicited similar immunoresponses in the MMR-RIT and MMR II groups. Both MMR vaccines resulted in comparable reactogenicity profiles, and no safety concerns were detected.

CONCLUSIONS

If licensed, the MMR-RIT could provide a valid option for the prevention of measles, mumps, and rubella in children in the United States and would reduce potential risks of a vaccine shortage.

Children's untreated decay is positively associated with past caries experience and with current salivary loads of mutans Streptococci; negatively with self-reported maternal iron supplements during pregnancy: a multifactorial analysis

OBJECTIVES

This study explored the association of children's salivary characteristics, past caries experience, birth weight, and reported maternal prenatal vitamin and mineral supplementation with the dental untreated decay of the child.

METHODS

This cross-sectional study, a sub-study of Griffith University Environments for Healthy Living birth cohort study, was conducted on 174 mother-child dyads. Mother's prenatal usage of vitamin and mineral supplements; child's birthweight; salivary pH, buffering capacity, and levels of salivary MS and LB were explored as risk indicators. Dental caries experience was assessed using International Caries Detection and Assessment System criteria. Path analysis was conducted to evaluate the association of risk indicators with children's current and past dental caries experience.

RESULTS

Children's past caries experience (β = 0.332, p = 0.018), and salivary MS counts (β = 0.215, p = 0.032) were positively associated with untreated decay at time of examination. With a trend towards significance, children whose mothers had reported taking iron supplements during pregnancy experienced lower levels of past caries (β = -0.137, p = 0.068) and untreated dental caries (β = -0.046, p = 0.051).

CONCLUSIONS

This study confirms that a child's levels of untreated decay is positively associated with their past caries, and that it correlates with current levels of salivary MS. Children of mothers who reported to have taken iron supplements during pregnancy experienced less caries throughout their lives. These observations confirm the importance to offspring of monitoring maternal health throughout pregnancy and of early monitoring of children's oral health in preventing future dental disease.

BET Bromodomain Inhibition Synergizes with PARP Inhibitor in Epithelial Ovarian Cancer

PARP inhibition is known to be an effective clinical strategy in BRCA mutant cancers, but PARP inhibition has not been applied to BRCA-proficient tumors. Here, we show the synergy of BET bromodomain inhibition with PARP inhibition in BRCA-proficient ovarian cancers due to mitotic catastrophe. Treatment of BRCA-proficient ovarian cancer cells with the BET inhibitor JQ1 downregulated the G2-M cell-cycle checkpoint regulator WEE1 and the DNA-damage response factor TOPBP1. Combining PARP inhibitor Olaparib with the BET inhibitor, we observed a synergistic increase in DNA damage and checkpoint defects, which allowed cells to enter mitosis despite the accumulation of DNA damage, ultimately causing mitotic catastrophe. Moreover, JQ1 and Olaparib showed synergistic suppression of growth of BRCA-proficient cancer in vivo in a xenograft ovarian cancer mouse model. Our findings indicate that a combination of BET inhibitor and PARP inhibitor represents a potential therapeutic strategy for BRCA-proficient cancers.

BET Inhibitors Suppress ALDH Activity by Targeting ALDH1A1 Super-Enhancer in Ovarian Cancer

The emergence of tumor cells with certain stem-like characteristics, such as high aldehyde dehydrogenase (ALDH) activity due to ALDH1A1 expression, contributes to chemotherapy resistance and tumor relapse. However, clinically applicable inhibitors of ALDH activity have not been reported. There is evidence to suggest that epigenetic regulation of stem-related genes contributes to chemotherapy efficacy. Here, we show that bromodomain and extraterminal (BET) inhibitors suppress ALDH activity by abrogating BRD4-mediated ALDH1A1 expression through a super-enhancer element and its associated enhancer RNA. The clinically applicable small-molecule BET inhibitor JQ1 suppressed the outgrowth of cisplatin-treated ovarian cancer cells both in vitro and in vivo Combination of JQ1 and cisplatin improved the survival of ovarian cancer-bearing mice in an orthotopic model. These phenotypes correlate with inhibition of ALDH1A1 expression through a super-enhancer element and other stem-related genes in promoter regions bound by BRD4. Thus, targeting the BET protein BRD4 using clinically applicable small-molecule inhibitors, such as JQ1, is a promising strategy for targeting ALDH activity in epithelial ovarian cancer. Cancer Res; 76(21); 6320-30. ©2016 AACR.

The bacteriome and mycobiome associated with oral squamous cell carcinoma: metagenomic analysis of samples from Yemeni and Sri Lankan cohorts

There is increasing interest in the possible role of the oral microbiome in oral squamous cell carcinoma (OSSC). However, studies on the possible association between the oral bacteriome and OSCC remain inconclusive, while the potential role of the “mycobiome” in oral carcinogenesis has never been explored. I hereby present results from our recent studies on the bacteriome and mycobiome associated with OSCC based on analysis of samples from Yemeni and Sri Lankan cohorts. Tissue biopsies were obtained from the cases while deep buccal swabs or fibro-epithelial polyps were collected from the controls. Sequencing of the bacterial V1-V3 region of the 16S rRNA gene and the fungal ITS2 region using Illumina’s 2x300 bp chemistry was employed to study the bacteriome and mycobiome, respectively. Merged reads were classified to species level using a BLASTN-algorithm. Downstream analyses were performed using QIIME, PICRUSt, and LEfSe. Fusobacterium nucleatum subsp. polymorphum, Pseudomonas aeruginosa, Prevotella and Campylobacter spp. were more abundant in OSCC samples while Streptococcus mitis and Rothia spp. were overrepresented in the controls. Functionally, inflammatory bacterial attributes including bacterial mobility, flagellar assembly, bacterial chemotaxis and LPS synthesis were enriched in the tumors. Mycobiome analysis revealed a dysbiotic fungal community dominated by C. albicans in association with OSCC.

Abstract A04: Aging microenvironment modulates melanoma invasion and metastasis

The incidence of melanoma rises dramatically after the age of 55. Due to an increase in aging population, it is important to study the change in molecular mechanisms due to aging that would allow development of therapies that are tailored to the age of the patients. The role of the tumor microenvironment in modulating cancer characteristics is widely recognized and it also provides targets for therapeutic intervention. Due to this, we hypothesized that changes in tumor microenvironment due to aging could affect the progression of the melanoma. We obtained skin fibroblasts from healthy donors aged 25-35, as well as skin fibroblasts from healthy donors aged 55-65. We cultured these fibroblasts and used conditioned media from them to affect the invasion of melanoma cells in 3D spheroid invasion assays, where aged fibroblasts promoted invasion of melanoma cells into collagen. We also built artificial skin (reconstructs) using young and aged fibroblasts and demonstrated that skin built with aged fibroblasts promoted melanoma cell invasion. Finally using a transgenic mouse model of melanoma (Yumm1.7, BRAFV600E/PTEN-/-) we observed that the injection of melanoma cells into the tail vein of aged mice (52 weeks) formed metastastic colonies much more rapidly than those injected into the tail vein of young mice (8 weeks). To study the factors involved in the aging microenvironment, we performed a proteomics study of the secretome from young and aged fibroblasts. From this study, we observed that aged fibroblasts secreted inhibitors of canonical Wnt signaling, as well as increased deposition of extracellular matrix components in the aging microenvironment. Since inhibition of canonical Wnt signaling has been linked to decreased sensitivity towards BRAF inhibitors in melanoma, we injected Yumm 1.7 cells subcutaneously into aged and young mice. These mice were then treated with BRAF inhibitors. We observed an increased resistance in response to therapy in the aged mice. We also prepared skin reconstruct from fibroblasts with knockdown of the proteins that we identified from secretome and treated them with PLX4720. These results indicated the role of these extracellular matrix proteins in melanoma. We are exploring the mechanisms of how these extracellular matrix proteins affect the sensitivity towards chemotherapeutics. We concluded that aging could alter tumor microenvironment thus resulting in increased metastasis and therapy resistance. It is important that the studies in cancer therapies take into account the age of the patient to achieve better response in patients.

Citation Format: Amanpreet Kaur, Katie Marchbank, Vanessa Dang, Michael O'Connell, Marie Webster, Jessica Appleton, Phil Cheng, Alexander Valiga, Rachel Morissette, Nazli McDonnell, Luigi Ferrucci, Andrew Kossenkov, Katrina Meeth, Marcus Bosenberg, Hsin-Yao Tang, Xiangfan Yin, William Wood, III, Elin Lehrmann, Kevin Becker, Keith Flaherty, Dennie Frederick, Jennifer Wargo, Katherine Aird, Rugang Zhang, Xiaowei Xu, Qin Liu, David Speicher, Ashani Weeraratna. Aging microenvironment modulates melanoma invasion and metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr A04.

Overcoming intrinsic multidrug resistance in melanoma by blocking the mitochondrial respiratory chain of slow-cycling JARID1B(high) cells

Despite success with BRAFV600E inhibitors, therapeutic responses in patients with metastatic melanoma are short-lived because of the acquisition of drug resistance. We identified a mechanism of intrinsic multidrug resistance based on the survival of a tumor cell subpopulation. Treatment with various drugs, including cisplatin and vemurafenib, uniformly leads to enrichment of slow-cycling, long-term tumor-maintaining melanoma cells expressing the H3K4-demethylase JARID1B/KDM5B/PLU-1. Proteome-profiling revealed an upregulation in enzymes of mitochondrial oxidative-ATP-synthesis (oxidative phosphorylation) in this subpopulation. Inhibition of mitochondrial respiration blocked the emergence of the JARID1B(high) subpopulation and sensitized melanoma cells to therapy, independent of their genotype. Our findings support a two-tiered approach combining anticancer agents that eliminate rapidly proliferating melanoma cells with inhibitors of the drug-resistant slow-cycling subpopulation.

Abstract 2510: Comparative proteomic analysis of melanoma cell secretomes reveals autophagy-related biomarkers

Autophagy is a highly conserved mechanism of cellular self-digestion that serves as a major protein and organelle degrading pathway and a critical adaptive response to nutrient, endoplasmic reticulum, and oxidative stress. Autophagy has been implicated as a survival mechanism in melanoma tumorigenesis and has been recognized as a primary mechanism of chemotherapeutic resistance. Pre-treatment analyses of autophagy levels in melanoma tumor samples have shown a high degree of heterogeneity across patients, with high levels of autophagy correlating with significantly shorter survival. However, quantitative assays for autophagy remain elusive at the pre-clinical level, impeding further understanding as to its role in melanoma progression. Another challenge to developing effective markers of autophagy is the striking difference in autophagic response of cells grown in conventional monolayer culture versus cells growing in the tumor microenvironment. Recent studies have found that autophagy regulates ‘unconventional’ protein secretion pathways, resulting in secretion of a subset of cytosolic proteins. Therefore, the focus of this work was to investigate molecular changes in the melanoma cell secretome as a means of identifying key proteins diagnostic of autophagy levels. To approximate autophagy dynamics in the tumor microenvironment, human melanoma cells were grown as spheroids in Type I bovine collagen matrices. To enrich for autophagy-related secretions, secretomes of low-autophagy WM793 cells and the genetically closely related high-autophagy 1205Lu cells were directly compared at baseline. Conditioned media was collected and separated using 1-D gel electrophoresis, digested with trypsin, and analyzed using liquid chromatography-tandem mass spectrometry analysis on an LTQ-Orbitrap hybrid instrument. Mass spectra were analyzed using the Rosetta ELUCIDATOR proteomic pipeline, and significance analysis of microarrays (SAM) was used to identify differentially secreted proteins. From Gene Ontology (GO) analysis, candidate biomarkers were enriched for extracellular matrix components, inflammatory mediators, and metabolic enzymes implicated in autophagy and melanoma progression. A subset of these proteins was predicted to be secreted via a non-classical mechanism using SecretomeP and SignalP secretory protein prediction servers. Network analysis using the shortest paths algorithm identified densely connected sub-networks that illustrated interplay between inflammatory cytokines and metastasis-related proteins, providing insight into molecular pathways that may regulate constitutively elevated autophagy. Our findings indicate that differences in basal autophagy in human melanoma manifest as secretory changes that could be novel serological biomarkers of autophagy for cancer prognosis and therapy.

Citation Format: Adam Akl, Ravi Amaravadi, David Speicher. Comparative proteomic analysis of melanoma cell secretomes reveals autophagy-related biomarkers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2510. doi:10.1158/1538-7445.AM2013-2510

Increased phospholipase A2 activity with phosphorylation of peroxiredoxin 6 requires a conformational change in the protein

We have shown previously and confirmed in this study that the phospholipase A(2) (PLA(2)) activity of peroxiredoxin 6 (Prdx6) is markedly increased by phosphorylation. This report evaluates the conformation and thermodynamic stability of Prdx6 protein after phosphorylation to understand the physical basis for increased activity. Phosphorylation resulted in decreased negative far-UV CD, strengthened ANS binding, and a lack of rigid tertiary structure, compatible with a change in conformation to that of a molten globule. The ΔG°(D) was 3.3 ± 0.3 kcal mol(-1) for Prdx6 and 1.7 ± 0.7 kcal mol(-1) for pPrdx6, suggesting that phosphorylation destabilizes the protein. Phosphorylation of Prdx6 changed the conformation of the N-terminal domain exposing Trp 33, as determined by tryptophan fluorescence and NaI fluorescence quenching. The kinetics of interaction of proteins with unilamellar liposomes (50:25:15:10 DPPC:egg PC:cholesterol:PG molar ratio) were evaluated with tryptophan fluorescence. pPrdx6 bound to liposomes with a higher affinity (K(d) = 5.6 ± 1.2 μM) than Prdx6 (K(d) = 24.9 ± 4.5 μM). By isothermal titration calorimetry, pPrdx6 bound to liposomes with a large exothermic heat loss (ΔH = -31.49 ± 0.22 kcal mol(-1)). Correlating our conformational studies with the published crystal structure of oxidized Prdx6 suggests that phosphorylation results in exposure of hydrophobic residues, thereby providing accessibility to the sites for liposome binding. Because binding of the enzyme to the phospholipid substrate interface is a requirement for PLA(2) activity, these results indicate that a change in the conformation of Prdx6 upon its phosphorylation is the basis for enhancement of PLA(2) enzymatic activity.

Timeless links replication termination to mitotic kinase activation

The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim) associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1). Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication.

Peroxiredoxin 6 phosphorylation and subsequent phospholipase A2 activity are required for agonist-mediated activation of NADPH oxidase in mouse pulmonary microvascular endothelium and alveolar macrophages

Peroxiredoxin 6 (Prdx6), a bifunctional enzyme with glutathione peroxidase and phospholipase A2 (PLA(2)) activities, participates in the activation of NADPH oxidase 2 (NOX2) in neutrophils, but the mechanism for this effect is not known. We now demonstrate that Prdx6 is required for agonist-induced NOX2 activation in pulmonary microvascular endothelial cells (PMVEC) and that the effect requires the PLA(2) activity of Prdx6. Generation of reactive oxygen species (ROS) in response to angiotensin II (Ang II) or phorbol 12-myristate 13-acetate was markedly reduced in perfused lungs and isolated PMVEC from Prdx6 null mice. Rac1 and p47(phox), cytosolic components of NOX2, translocated to the endothelial cell membrane after Ang II treatment in wild-type but not Prdx6 null PMVEC. MJ33, an inhibitor of Prdx6 PLA(2) activity, blocked agonist-induced PLA(2) activity and ROS generation in PMVEC by >80%, whereas inhibitors of other PLA(2)s were ineffective. Transfection of Prx6 null cells with wild-type and C47S mutant Prdx6, but not with mutants of the PLA(2) active site (S32A, H26A, and D140A), "rescued" Ang II-induced PLA(2) activity and ROS generation. Ang II treatment of wild-type cells resulted in phosphorylation of Prdx6 and its subsequent translocation from the cytosol to the cell membrane. Phosphorylation as well as PLA(2) activity and ROS generation were markedly reduced by the MAPK inhibitor, U0126. Thus, agonist-induced MAPK activation leads to Prdx6 phosphorylation and translocation to the cell membrane, where its PLA(2) activity facilitates assembly of the NOX2 complex and activation of the oxidase.

A disintegrin and metalloprotease protein-12 as a novel marker for the diagnosis of ectopic pregnancy

OBJECTIVE

To evaluate the performance of a novel biomarker, a disintegrin and metalloprotease-12 (ADAM-12), to differentiate an ectopic pregnancy (EP) from normal intrauterine pregnancies (IUPs).

DESIGN

Case-control study.

SETTING

Three urban academic centers.

PATIENT(S)

Women who were seen in the emergency department with pain or bleeding in the first trimester of pregnancy.

INTERVENTION(S)

Sera from women with diagnosed EP or IUP were evaluated via proteomics and an ADAM-12 dissociation-enhanced lanthanide fluoroimmunoassay.

MAIN OUTCOME MEASURE(S)

Differences between groups, area under the receiver operating curve, sensitivity, and specificity.

RESULT(S)

Via a proteomics evaluation, we found a statistically significant decrease in ADAM-12 in the sera of patients with EP, which we confirmed in a larger group of 199 patients (median IUP 18.6 ng/mL versus median EP 2.5 ng/mL with good discrimination between the groups as assessed by receiver operating characteristics [area under the curve = 0.82]). At a low cut-point, the sensitivity was 70% and specificity 84%, but, at a higher cut-point optimizing sensitivity, the ADAM-12 test demonstrated a sensitivity of 97%.

CONCLUSION(S)

ADAM-12 is a promising marker for the diagnosis of EP in women with symptoms in the first trimester, validating the proteomics findings. Further studies in additional patient populations and in combination with other biomarkers are needed.

Gene expression profiles in peripheral blood mononuclear cells can distinguish patients with non-small cell lung cancer from patients with nonmalignant lung disease

Early diagnosis of lung cancer followed by surgery presently is the most effective treatment for non-small cell lung cancer (NSCLC). An accurate, minimally invasive test that could detect early disease would permit timely intervention and potentially reduce mortality. Recent studies have shown that the peripheral blood can carry information related to the presence of disease, including prognostic information and information on therapeutic response. We have analyzed gene expression in peripheral blood mononuclear cell samples including 137 patients with NSCLC tumors and 91 patient controls with nonmalignant lung conditions, including histologically diagnosed benign nodules. Subjects were primarily smokers and former smokers. We have identified a 29-gene signature that separates these two patient classes with 86% accuracy (91% sensitivity, 80% specificity). Accuracy in an independent validation set, including samples from a new location, was 78% (sensitivity of 76% and specificity of 82%). An analysis of this NSCLC gene signature in 18 NSCLCs taken presurgery, with matched samples from 2 to 5 months postsurgery, showed that in 78% of cases, the signature was reduced postsurgery and disappeared entirely in 33%. Our results show the feasibility of using peripheral blood gene expression signatures to identify early-stage NSCLC in at-risk populations.

The HUPO Plasma Proteome Project: a report from the Munich congress

The Human Proteome Organization has several major collaborative research initiatives, including the Plasma Proteome Project. A major feature of the HUPO World Congress in Munich in August 2005 was the release of the special issue of PROTEOMICS with 28 articles from the pilot phase of the Plasma Proteome Project. An open Workshop and a presentation in the closing plenary session of the congress focused on next phases for the Plasma Proteome Project.

The CBP bromodomain and nucleosome targeting are required for Zta-directed nucleosome acetylation and transcription activation

The Epstein-Barr virus (EBV)-encoded lytic activator Zta is a bZIP protein that can stimulate nucleosomal histone acetyltransferase (HAT) activity of the CREB binding protein (CBP) in vitro. We now show that deletion of the CBP bromo- and C/H3 domains eliminates stimulation of nucleosomal HAT activity in vitro and transcriptional coactivation by Zta in transfected cells. In contrast, acetylation of free histones was not affected by the addition of Zta or by deletions in the bromo or C/H3 domain of CBP. Zta stimulated acetylation of oligonucleosomes assembled on supercoiled DNA and dinucleosomes assembled on linear DNA, but Zta-stimulated acetylation was significantly reduced for mononucleosomes. Western blotting and amino-terminal protein sequencing indicated that all lysine residues in the H3 and H4 amino-terminal tails were acetylated by CBP and enhanced by the addition of Zta. Histone acetylation was also dependent upon the Zta basic DNA binding domain, which could not be substituted with the homologous basic region of c-Fos, indicating specificity in the bZIP domain nucleosome binding function. Finally, we show that Zta and CBP colocalize to viral immediate-early promoters in vivo and that overexpression of Zta leads to a robust increase in H3 and H4 acetylation at various regions of the EBV genome in vivo. Furthermore, deletion of the CBP bromodomain reduced stable CBP-Zta complex formation and histone acetylation at Zta-responsive viral promoters in vivo. These results suggest that activator- and bromodomain-dependent targeting to oligonucleosomal chromatin is required for stable promoter-bound complex formation and transcription activity.

Immunogenicity of recombinant GA733-2E antigen (CO17-1A, EGP, KS1-4, KSA, Ep-CAM) in gastro-intestinal carcinoma patients

Targeting the GA733 antigen (also known as CO17-1A, EGP, KS1-4, KSA, Ep-CAM) by monoclonal antibody CO17-1A or anti-idiotypic antibodies mimicking the CO17-1A or GA733 epitope has induced prolonged survival and specific immune responses to the antigen, respectively, in colorectal cancer (CRC) patients. In pre-clinical studies in mice and rabbits, recombinant baculovirus-derived GA733-2E antigen was superior to anti-idiotypic antibodies at modulating specific immune responses. Our aim was to evaluate the immunogenicity and potential toxicity of alum-precipitated GA733-2E in a phase I trial in patients with resected CRC or pancreatic cancer. Six patients with advanced pancreatic carcinoma and 6 with CRC Dukes' stage A, B or C received between 4 and 7 doses of alum-precipitated GA733-2E at 50, 200 or 800 microg/dose at monthly intervals. Antibody binding to GA733-2E or antigen-positive CRC cells was determined, as were antigen-specific proliferative, cytolytic T-lymphocyte and delayed-type hypersensitivity responses. Six of the 12 patients developed antigen-specific humoral immune responses after immunotherapy, and 8 developed cellular immune responses. The overall immune response rate, including patients with humoral and/or cellular immune responses, was 83%. Median overall survival of the CRC and pancreatic cancer patients was 39.8 and 11.2 months, respectively. Following 18 years of single-epitope targeting of the GA733 antigen, immunization of patients against multiple epitopes of the antigen frequently induces an immune response in the absence of significant toxicity, despite relatively widespread expression of this antigen on normal epithelial cells.

Isolation of the melanoma-associated antigen p23 using antibody phage display

The general responsiveness of human melanoma to immunotherapy has been well established, but active immunotherapy of melanoma has been hampered by insufficient information on the immunogenicity of melanoma-associated Ags in patients. In this study, we isolated a recombinant phage-Fab clone (A10-5) from a phage-Fab library derived from the B cells of a melanoma patient in remission after immunotherapy. Purified A10-5 Fab bound at high levels to cultured melanoma cell lines and to tissue sections of metastatic and vertical growth phase primary melanoma, but not to radial growth phase primary melanoma, nevi, or normal skin. A10-5 Fab bound to both the surface and the cytoplasm of cultured melanoma cells, but only to the cytoplasm of cultured fibroblasts. Western blot analysis revealed A10-5 Fab reactivity with a 33- and a 23-kDa glycoprotein under nonreducing conditions, and with a 23-kDa protein only under reducing conditions. A cDNA with an open reading frame predicted to encode a 23-kDa protein was cloned by screening a melanoma cell cDNA library with A10-5 Fab. This protein (p23) is the human homologue of the murine tumor transplantation Ag P198 that interacts with the cytoplasmic domain of ErbB-3 expressed by melanoma cells. Thus, the Ab phage display method has identified a novel, stage-specific melanoma-associated Ag that may have therapeutic and diagnostic value.

Colorectal cancer vaccines: antiidiotypic antibody, recombinant protein, and viral vector

The colorectal cancer antigen GA733 (also termed CO17-1A, KSI-4, Ep-CAM, KSA) has proved to be a useful target in passive immunotherapy with monoclonal antibody and in active immunotherapy with antiidiotypic antibodies in cancer patients. The GA733 antigen was molecularly cloned and expressed in baculovirus (BV), adenovirus (AV), and vaccinia virus (VV). Recombinant BV-, VV-, and AV-GA733 induced antigen-specific cytotoxic antibodies and proliferative and delayed-type hypersensitive lymphocytes. However, only the AV recombinant induced antigen-specific cytolytic T lymphocytes and regression of established tumors. Cured mice were protected against challenge with antigen-negative tumors, indicating antigen spreading of immune responses. In a model of active immunotherapy against the murine homologue of the human GA733 antigen, murine epithelial glycoprotein (mEGP), BV-derived mEGP protein in various adjuvants did not protect mice against a challenge with mEGP-positive tumors. AV mEGP, only when combined with interleukin-2, significantly inhibited growth of established mEGP-positive tumors. This is in contrast to the same vaccine expressing the human antigen that was effective without interleukin-2. AV GA733, in combination with interleukin-2, is a candidate vaccine for colorectal cancer patients.

Identification of a survival-promoting peptide in medium conditioned by oxidatively stressed cell lines of nervous system origin

A survival-promoting peptide has been purified from medium conditioned by Y79 human retinoblastoma cells and a mouse hippocampal cell line (HN 33.1) exposed to H2O2. A 30 residue synthetic peptide was made on the basis of N-terminal sequences obtained during purification, and it was found to exhibit gel mobility and staining properties similar to the purified molecules. The peptide maintains cells and their processes in vitro for the HN 33.1 cell line treated with H2O2, and in vivo for cortical neurons after lesions of the cerebral cortex. It has weak homology with a fragment of a putative bacterial antigen and, like that molecule, binds IgG. The peptide also contains a motif reminiscent of a critical sequence in the catalytic region of calcineurin-type phosphatases; surprisingly, like several members of this family, the peptide catalyzes the hydrolysis of para-nitrophenylphosphate in the presence of Mn2+. Application of the peptide to one side of bilateral cerebral cortex lesions centered on area 2 in rats results in an increase in IgG immunoreactivity in the vicinity of the lesions 7 d after surgery. Microglia immunopositive for IgG and ED-1 are, however, dramatically reduced around the lesions in the treated hemisphere. Furthermore, pyramidal neurons that would normally shrink, die, or disintegrate were maintained, as determined by MAP2 immunocytochemistry and Nissl staining. These survival effects were often found in both hemispheres. The results suggest that this peptide operates by diffusion to regulate the immune response and thereby rescue neurons that would usually degenerate after cortical lesions. The phosphatase activity of this molecule also suggests the potential for direct neuron survival-promoting effects.

Colorectal carcinoma invasion inhibition by CO17-1A/GA733 antigen and its murine homologue

BACKGROUND

The gastrointestinal carcinoma antigen GA733 is a potential target for passive and active immunotherapy for patients with colorectal carcinoma. This antigen has been characterized previously as a homophilic adhesion (i.e., adhesion to self) protein, but the functional consequences of homophilic adhesion for tumor growth and invasion are unknown. The availability of a murine homologue of GA733, i.e., murine epithelial glycoprotein (mEGP), allows for functional analysis of cell adhesion as it relates to tumor growth and invasion, both in vitro and in vivo.

METHODS

CT-26 murine colorectal carcinoma cells were transfected with complementary DNAs encoding either the human or the murine antigen. GA733- or mEGP-producing cells were evaluated for homophilic adhesion, growth on plastic surfaces, colony formation in soft agar, and invasion through a reconstructed basement membrane (Matrigel). mEGP-producing cells were also examined for their capacity to metastasize in mice. Reported P values are two-sided.

RESULTS

Compared with control cells, mEGP-producing cells showed significantly lower growth rates, colony formation, and invasion through Matrigel in vitro (all P values <.05). Compared with vector-only transfected cells and parental cells, mEGP-producing cells showed a reduction in metastatic potential in syngeneic immunodeficient and immunocompetent mice (all P values <.05). In contrast to mEGP-transfected cells, GA733-transfected cells did not exhibit significantly reduced growth or colony formation in vitro (all P values >.05). However, GA733-transfected cells did show reduced invasion through Matrigel compared with vector-only transfected cells or parental cells (all P values <.05).

CONCLUSION

The adhesion proteins GA733 and mEGP inhibit invasion of tumor cells.

Melanoma cell-cell interactions are mediated through heterophilic Mel-CAM/ligand adhesion

Mel-cell adhesion molecule (CAM), also known as MUC18 and CD146, is a novel member of the immunoglobulin supergene family. Mel-CAM was first identified as an integral membrane glycoprotein in human melanoma and is also abundantly expressed by endothelial cells of various origins. In a previous study (I. M. Shih et al., Cancer Res., 54: 2514-2520, 1994), we showed that Mel-CAM is a cell-cell adhesion molecule with a possible role in melanoma invasion and metastasis. Here, we define the molecular mechanism responsible for cell-cell adhesion of Mel-CAM and demonstrate its role in melanoma-endothelial cell interactions. Most of human melanoma cells, including Mel-CAM-negative SBcl-2 cells, adhered to nitrocellulose-immobilized Mel-CAM produced by baculovirus recombinants. This adhesion can be blocked by full-length Mel-CAM or polyclonal antiserum against Mel-CAM. Adhesion is not affected by the presence of EDTA, truncated Mel-CAM extracellular domain, or heparan sulfate proteoglycan. In cell aggregation assays, Mel-CAM-negative SBcl-2 cells cluster with U937TM cells (U937 transfected with Mel-CAM cDNA) but not with control nontransfectants, suggesting that SBcl-2 cells express the ligand for Mel-CAM. SBcl-2 cells also form heterotypic aggregates with Mel-CAM-positive human endothelial cells but not with Mel-CAM-negative but ligand-positive smooth muscle cells. Taken together, our results show that Mel-CAM mediates cell-cell adhesion through heterophilic adhesion to an as yet unidentified ligand present on melanoma but not on endothelial cells. Thus, melanoma-endothelial interactions during metastasis may occur through this novel mechanism.

Amino-acid substitution in alpha-spectrin commonly coinherited with nondominant hereditary spherocytosis

Nondominant hereditary spherocytosis (ndHS) is a disorder characterized in some patients by severe hemolytic anemia and marked deficiency of erythrocyte spectrin. This report describes the identification of a variant spectrin chain, alpha-spectrin Bughill or alpha(BH), that is associated with this disorder in a number of patients. Tryptic maps of spectrin from affected individuals revealed an acidic shift in isoelectric point of the alphaII domain peptides at 46 kD and 35 kD. A point mutation at codon 970 of the alpha-spectrin gene (GCT-->GAT), that changes the encoded amino acid from an alanine to an aspartic acid, was identified in genomic DNA of affected patients. The alpha(BH) variant was present in 8 patients with ndHS from five different kindreds but was absent in 4 patients from two other kindreds. The 8 ndHS patients with the alpha(BH) variant appeared to be homozygous for the alpha(BH) variant by analysis of peptide maps of limited tryptic digests of erythrocyte spectrin. However, following genomic DNA analysis, only 2 of these patients were true homozygotes, whereas 6 were found to be doubly heterozygous for the alpha(BH) allele and a second, presumably abnormal, alpha-spectrin gene. These results suggest that, in these 6 patients, the second alpha-spectrin allele is in fact associated with one or more genetic defect(s), causing decreased accumulation of alpha-spectrin. The pattern of transmission of the alpha(BH) allele in certain families suggests that the alpha(BH) amino-acid substitution is not itself responsible for ndHS but is more likely a polymorphic variant that, in some but not all cases, is in linkage disequilibrium with another uncharacterized alpha-spectrin gene defect that itself is a cause of ndHS.

Purification and characterization of double-stranded RNA adenosine deaminase from bovine nuclear extracts

The double-stranded RNA (dsRNA) adenosine deaminase (DRADA) deaminates adenosine residues to inosines and creates I-U mismatched base pairs in dsRNAs. Its involvement in RNA editing of glutamate-gated ion channel gene transcripts in mammalian brains has been proposed as one of the biological functions for this recently identified cellular enzyme. We purified a mixture of three forms, 93, 88, and 83 kDa, of bovine DRADA proteins, all likely to be active enzymes. We determined that DRADA has a native molecular mass of approximately 100 kDa, suggesting that the enzyme exists as a monomer. The purified enzyme was not inhibited by 2'-deoxycoformycin, a transition state analog inhibitor of adenosine deaminase and AMP deaminase, suggesting that the catalytic mechanism of DRADA might be different from that of other deaminases. DRADA binds specifically to dsRNA with a dissociation constant of 0.23 nM for a synthetic dsRNA, and the Michaelis constant is 0.85 nM. These values indicate that DRADA has a much higher affinity for its substrate than other deaminases such as adenosine deaminase and AMP deaminase. DRADA may need this extremely high affinity to catalyze efficiently the modification of relatively rare substrate RNAs in the cell nucleus.

Isolation and functional characterization of the A32 melanoma-associated antigen

Cell surface melanoma-associated antigens can mediate cell-cell or cell-substrate adhesion, signal transduction, proteolysis, or immune recognition and play a key role in determining invasive and metastatic competence of the tumor cells. The melanoma-associated antigen, A32, was defined by a murine monoclonal antibody and was immunoprecipitated as a single 113 kDa integral membrane glycoprotein containing sialic acid and HNK-1 carbohydrate moieties. Immunohistochemistry revealed the presence of A32 antigen on most melanomas and nevi but not on normal epidermal melanocytes. Of the normal tissues tested, only endothelium, smooth muscle, cerebellum, and hair follicles expressed the A32 antigen. Tryptic peptides of the A32 antigen obtained after immunoaffinity chromatography showed sequence identity to MUC18 antigen, a member of the immunoglobulin supergene family. Melanoma cells adhered to affinity-purified A32 antigen immobilized to a solid phase, and the adhesion was blocked by either soluble A32 antigen or monoclonal antibody against the HNK-1 carbohydrate moiety. These findings, together with the observation that A32 antigen is concentrated in cell-cell contact borders, suggest that this antigen is an adhesion molecule with a possible role in tumor invasion and metastasis.

Biochemical and functional characterization of aminopeptidase N expressed by human melanoma cells

A cell surface protein expressed on melanoma cells, but not on normal melanocytes, was biochemically and functionally characterized. Microsequencing of the M(r) 143,000 affinity-purified protein revealed amino acid sequence identity to aminopeptidase N (EC 3.4.11.2). In situ expression, indirect immunofluorescence, and Western blotting demonstrated that aminopeptidase N is tightly associated with extracellular matrix components. A specific polyclonal antiserum and the competitive inhibitors of aminopeptidase N, bestatin and amastatin, inhibited invasion of an aminopeptidase N-expressing metastatic melanoma cell line through the reconstituted basement membrane Matrigel in a dose-dependent manner. In vitro digestion of Matrigel with affinity-purified aminopeptidase N revealed an enzyme-sensitive M(r) 160,000 protein. These experiments suggest a role for aminopeptidase N in melanoma invasion of basement membranes.

Gamma-interferon-induced nerve growth factor receptors in colorectal carcinoma cell lines

Gamma-interferon (gamma IFN) was found to induce expression of the 150,000 M(r) cell surface and the 35,000 M(r) chromatin receptors for nerve growth factor (NGF) in the SW1116 colorectal carcinoma cell line that does not express NGF receptors. In the SW707 colorectal carcinoma cell line that expresses a low level of NGF receptors, gamma IFN stimulated expression of the cell surface and the nuclear receptors. Induction of NGF receptors in SW1116 cells resulted in internalization and nuclear translocation of 125I-NGF. When NGF bound to the chromatin, ribosomal RNA synthesis was inhibited. Two-dimensional gel electrophoresis of [35S]methionine-labeled chromatin proteins indicated significant changes in chromatin protein composition in cells treated and not-treated with gamma IFN. gamma IFN effectively stimulated the expression of NGF receptors in two colorectal carcinoma cell lines, but inhibited the expression in melanoma and breast carcinoma cells. It is suggested that gamma IFN, by modulating the expression of NGF receptors may affect the NGF-dependent growth of some tumor cell lines.

Characterization of tenascin secreted by human melanoma cells

Tenascin is a large glycoprotein of the extracellular matrix. It shows a site-restricted expression during embryogenesis and can be found in adult tissues during wound healing and tumorigenesis. Because of the potential involvement of tenascin in adhesion and invasion during metastasis, the study of the interactions of tumor cells with tenascin is of considerable interest. Using five anti-melanoma monoclonal antibodies to four different epitopes of human tenascin, we found that most melanoma cells secrete tenascin in vitro constitutively. Transforming growth factor beta 1 in the medium increased secretion in tenascin-producing cells. Tenascin was present in sera of melanoma patients, with significantly elevated levels in patients with advanced melanomas as compared to patients with low tumor burden or to normal donors. Normal and malignant melanocytes did not attach to tenascin as substrate within 1 to 2 h and tenascin could also inhibit fibronectin-dependent adhesion. These results indicate that tenascin may play a critical role in cell-substrate interactions of melanoma cells.

cDNA sequence for human erythrocyte ankyrin

The cDNA for human erythrocyte ankyrin has been isolated from a series of overlapping clones obtained from a reticulocyte cDNA library. The composite cDNA sequence has a large open reading frame of 5636 base pairs (bp) with the complete coding sequence for a polypeptide of 1879 amino acids with a predicted molecular mass of 206 kDa. The derived amino acid sequence contained 194 residues that were identical to those obtained by direct amino acid sequencing of 11 ankyrin proteolytic peptides. The primary sequence contained 23 highly homologous repeat units of 33 amino acids within the 90-kDa band 3 binding domain. Two cDNA clones showed evidence of apparent mRNA processing, resulting in the deletions of 486 bp and 135 bp, respectively. The 486-bp deletion resulted in the removal of a 16-kDa highly acidic peptide, and the smaller deletion had the effect of altering the COOH terminus of the molecule. Radiolabeled ankyrin cDNAs recognized two erythroid message sizes by RNA blot analysis, one of which was predominantly associated with early erythroid cell types. An ankyrin message was also observed in RNA from the human cerebellum by the same method. The ankyrin gene is assigned to chromosome 8 using genomic DNA from a panel of sorted human chromosomes.

Complete amino acid sequence and homologies of human erythrocyte membrane protein band 4.2

The complete amino acid sequence for human erythrocyte band 4.2 has been derived from the nucleotide sequence of a full-length 2.35-kilobase (kb) cDNA. The 2.35-kb cDNA was isolated from a human reticulocyte cDNA library made in the expression vector lambda gt11. Of the 2348 base pairs (bp), 2073 bp encode 691 amino acids representing 76.9 kDa (the SDS/PAGE molecular mass is 72 kDa). RNA blot analysis of human reticulocyte total RNA gives a message size for band 4.2 of 2.4 kb. The amino acid sequence of band 4.2 has homology with two closely related Ca2(+)-dependent cross-linking proteins, guinea pig liver transglutaminase (protein-glutamine gamma-glutamyltransferase; protein-glutamine: amine gamma-glutamyltransferase, EC 2.3.2.13) (32% identity in a 446-amino acid overlap) and the a subunit of human coagulation factor XIII (27% identity in a 639-amino acid overlap), a transglutaminase that forms intermolecular gamma-glutamyl-epsilon-lysine bonds between fibrin molecules. The region of greatest identity includes a 49-amino acid stretch of band 4.2, which is 69% and 51% identical with guinea pig liver transglutaminase and the a subunit of factor XIII, respectively, within the regions that contain the active sites of these enzymes. Significantly, within the five contiguous consensus residues of the transglutaminase active site, Gly-Gln-Cys-Trp-Val, band 4.2 has an alanine substituted for cysteine (which is apparently essential for activity). Consistent with this active site substitution, erythrocyte membranes or inside-out vesicles, which contain band 4.2, show no evidence of transglutaminase activity by two types of in vitro assay.

Sequence investigation of the major gastrointestinal tumor-associated antigen gene family, GA733

The monoclonal antibody-defined, tumor-associated antigen GA733 was purified from the SW948 human colorectal carcinoma cell line and its partial amino acid sequence was determined. By using a synthetic oligonucleotide probe, two recombinants were isolated from a total human genomic library. We prove the existence of a family of GA733 genes. One of the genomic isolates is demonstrated to be an intronless gene, which is transcribed in pancreatic carcinoma cell lines and in placenta. The GA733 proteins were observed to contain sequences homologous to a repeat unit occurring 10 times in thyroglobulin and once in the HLA-DR-associated invariant chain. A more evolutionarily distant relationship was found with the alpha chain of the interleukin 2 growth factor receptor.

Characterization of cholecystokinin from the human brain

Human forms of cholecystokinin have not previously been characterized chemically. In this study, we have extracted and purified the predominant molecular form of cholecystokinin present in human cerebral cortex. The peptide was characterized by amino acid analysis, automated peptide sequencing, and fast atom bombardment mass spectrometry. It appears to be identical to porcine cholecystokinin-octapeptide, with the sequence of Asp-Tyr(SO3)-Met-Gly-Trp-Met-Asp-Phe(NH2). This structural identity is consistent with the observations that the peptide in human brain and porcine cholecystokinin-octapeptide are recognized similarly by a battery of antisera to porcine cholecystokinin; that they coelute from several chromatographic systems, including gel filtration, ion exchange, and reversed-phase; and that they possess similar biological activities.