Neuropeptide-induced androgen independence in prostate cancer cells: roles of nonreceptor tyrosine kinases Etk/Bmx, Src, and focal adhesion kinase

The bombesin/gastrin-releasing peptide (GRP) family of neuropeptides has been implicated in various in vitro and in vivo models of human malignancies including prostate cancers. It was previously shown that bombesin and/or neurotensin (NT) acts as a survival and migratory factor(s) for androgen-independent prostate cancers. However, a role in the transition from an androgen-dependent to -refractory state has not been addressed. In this study, we investigate the biological effects and signal pathways of bombesin and NT on LNCaP, a prostate cancer cell line which requires androgen for growth. We show that both neurotrophic factors can induce LNCaP growth in the absence of androgen. Concurrent transactivation of reporter genes driven by the prostate-specific antigen promoter or a promoter carrying an androgen-responsive element (ARE) indicate that growth stimulation is accompanied by androgen receptor (AR) activation. Furthermore, neurotrophic factor-induced gene activation was also present in PC3 cells transfected with the AR but not in the parental line which lacks the AR. Given that bombesin does not directly bind to the AR and is known to engage a G-protein-coupled receptor, we investigated downstream signaling events that could possibly interact with the AR pathway. We found that three nonreceptor tyrosine kinases, focal adhesion kinase (FAK), Src, and Etk/BMX play important parts in this process. Etk/Bmx activation requires FAK and Src and is critical for neurotrophic factor-induced growth, as LNCaP cells transfected with a dominant-negative Etk/BMX fail to respond to bombesin. Etk's activation requires FAK, Src, but not phosphatidylinositol 3-kinase. Likewise, bombesin-induced AR activation is inhibited by the dominant-negative mutant of either Src or FAK. Thus, in addition to defining a new G-protein pathway, this report makes the following points regarding prostate cancer. (i) Neurotrophic factors can activate the AR, thus circumventing the normal growth inhibition caused by androgen ablation. (ii) Tyrosine kinases are involved in neurotrophic factor-mediated AR activation and, as such, may serve as targets of future therapeutics, to be used in conjunction with current antihormone and antineuropeptide therapies.

High spatial resolution imaging with near-field scanning optical microscopy in liquids

The mechanism of tuning fork-based shear-force near-field scanning optical microscopy is investigated to determine optimal experimental conditions for imaging soft samples immersed in liquid. High feedback sensitivity and stability are obtained when only the fiber probe, i.e., excluding the tuning fork prongs, is immersed in solution, which also avoids electrical shorting in conductive (i.e., buffer) solutions. Images of MEH-PPV were obtained with comparable spatial resolution in both air and water. High optical resolution (approximately160 nm fwhm) was observed.

Development and characterization of monoclonal antibodies to subgroup J avian leukosis virus

In an attempt to develop a specific diagnostic test for avian leukosis virus (ALV) subgroup J (ALV-J) strain Hc1, four monoclonal antibodies (MAbs), JE9, G2, 145, and J47, were generated that are specific for ALV-J envelope glycoprotein, gp85. Polymerase chain reaction (PCR) was used to amplify genomic pro-viral DNA of Avian Disease and Oncology Laboratory (ADOL)-Hc1 and ADOL-4817 envelope genes. Both open reading frames encoding glycoproteins gp85 and gp37 were cloned into baculoviruses. Abundant expression of gp85 and gp37 was detected in the recombinant viruses with specific antibody to Hc1 strain of the ALV-J. The expressed proteins were used for immunization of mice to produce hybridoma cell lines secreting MAbs specific to ALV-J envelope protein. A panel of MAbs was generated by fusing NS1 myeloma cells and spleen cells from mice immunized with the recombinant baculoviruses. With the use of an immunofluorescence assay, three MAbs (JE9, G2, 145) reacted with ALV-J but not with subgroups A, B, C, D, or E of ALV. MAb J47 reacted with all exogenous subgroups of ALV including A, B, C, D, and J but not with endogenous subgroup E viruses. Western blot analysis was performed with all four MAbs against recombinant baculovirus and Hc1-infected chicken embryo fibroblast (CEF) lysates. A major band with a molecular weight about 90 kD corresponding to the size of ALV-J envelope was consistently obtained. With these MAbs, we detected the Hc1 antigen in CEFs infected with several ALV-J viruses isolated in the United States and also in tissue sections from chickens infected with Hc1 strain of ALV-J. These MAbs will be useful reagents for the diagnosis of ALV-J infection because they recognize a common antigenic epitope in six isolates tested thus far.

Marek's disease virus infection in the brain: virus replication, cellular infiltration, and major histocompatibility complex antigen expression

Marek's disease virus (MDV) infection in the brain was studied chronologically after inoculating 3-week-old chickens of two genetic lines with two strains of serotype I MDV representing two pathotypes (v and vv+). Viral replication in the brain was strongly associated with the development of lesions. Three viral antigens (pp38, gB, and meq) were detected in the brain of infected chickens. Marked differences between v and vv+ pathotypes of MDV were identified for level of virus replication, time course of brain lesions, and expression of major histocompatibility complex (MHC) antigens. Two pathologic phenomena (inflammatory and proliferative) were detected in the brain of chickens inoculated with vv+MDV, but only inflammatory lesions were observed in those inoculated with vMDV. Inflammatory lesions, mainly composed of macrophages, CD4+ T cells, and CD8+ T cells, started at 6-10 days postinoculation (dpi) and were transient. Proliferative lesions, characterized by severe infiltrates of CD4+CD8- T cells (blasts), started at 19-26 dpi and persisted. Expression of MHC antigens in endothelial cells and infiltrating cells within the brain was influenced by MDV infection. Upregulation of MHC class II antigen occurred in all treatment groups, although it was more severe in those inoculated with vv+MDV. MHC class I antigen was downregulated only in those groups inoculated with vv+MDV. These results enhance our understanding of the nature and pattern of MDV infection in the brain and help to explain the neurovirulence associated with highly virulent MDV.

Glycoproteins H and L of Marek's disease virus form a hetero-oligomer essential for translocation and cell surface expression

Glycoproteins H and L form a hetero-oligomeric complex (gH-L) which plays an important role in virus entry to host cells and cell-to-cell infection in herpesviruses. Interaction of gH and gL is considered to be critical for the biological function of these two glycoproteins. To investigate the interaction of MDV gH and gL, both gH and gL were expressed in in vitro cell culture systems using indirect immunofluorescence assay with gH and gL antibodies. The results suggested that co-expression of gH and gL in the same cells are required and necessary for both gH and gL subcellular translocation and cell surface expression. gL expressed in recombinant fowlpox virus (rFPV) infected chicken embryo fibroblasts (CEF) was consistently secreted into the culture medium. The primary peptide of gL binds with that of gH in the cytosol or ER lumen. By binding with gH, gL could anchor itself on the cell surface allowing for surface expression and viral spread to uninfected cells. The binding domain of gH was mapped to the amino acids 451-659 (SacI-HindIII) fragment and was essential for gH-L complex formation.

Marek's disease virus (MDV) encodes an interleukin-8 homolog (vIL-8): characterization of the vIL-8 protein and a vIL-8 deletion mutant MDV

Chemokines induce chemotaxis, cell migration, and inflammatory responses. We report the identification of an interleukin-8 (IL-8) homolog, termed vIL-8, encoded within the genome of Marek's disease virus (MDV). The 134-amino-acid vIL-8 shares closest homology to mammalian and avian IL-8, molecules representing the prototype CXC chemokine. The gene for vIL-8 consists of three exons which map to the BamHI-L fragment within the repeats flanking the unique long region of the MDV genome. A 0.7-kb transcript encoding vIL-8 was detected in an n-butyrate-treated, MDV-transformed T-lymphoblastoid cell line, MSB-1. This induction is essentially abolished by cycloheximide and herpesvirus DNA polymerase inhibitor phosphonoacetate, indicating that vIL-8 is expressed with true late (gamma2) kinetics. Baculovirus-expressed vIL-8 was found to be secreted into the medium and shown to be functional as a chemoattractant for chicken peripheral blood mononuclear cells but not for heterophils. To characterize the function of vIL-8 with respect to MDV infection in vivo, a recombinant MDV was constructed with a deletion of all three exons and a soluble-modified green fluorescent protein (smGFP) expression cassette inserted at the site of deletion. In two in vivo experiments, the vIL-8 deletion mutant (RB1BvIL-8DeltasmGFP) showed a decreased level of lytic infection in comparison to its parent virus, an equal-passage-level parent virus, and to another recombinant MDV containing the insertion of a GFP expression cassette at the nonessential US2 gene. RB1BvIL-8DeltasmGFP retained oncogenicity, albeit at a greatly reduced level. Nonetheless, we have been able to establish a lymphoblastoid cell line from an RB1BvIL-8DeltasmGFP-induced ovarian lymphoma (MDCC-UA20) and verify the presence of a latent MDV genome lacking vIL-8. Taken together, these data describe the identification and characterization of a chemokine homolog encoded within the MDV genome that is dispensable for transformation but may affect the level of MDV in vivo lytic infection.

Marek's disease virus down-regulates surface expression of MHC (B Complex) Class I (BF) glycoproteins during active but not latent infection of chicken cells

Infection of chicken cells with three Marek's disease virus (MDV) serotypes interferes with expression of the major histocompatibility complex (MHC or B complex) class I (BF) glycoproteins. BF surface expression is blocked after infection of OU2 cells with MDV serotypes 1, 2, and 3. MDV-induced T-cell tumors suffer a nearly complete loss of cell surface BF upon virus reactivation with 5-bromo-2'-deoxyuridine (BUdR). The recombinant virus (RB1BUS2gfpDelta) transforming the MDCC-UA04 cell line expresses green fluorescent protein (GFP) during the immediate early phase of viral gene expression. Of the UA04 cells induced to express the immediate early GFP, approximately 60% have reduced levels of BF expression. All of the reactivated UA04 and MSB1 tumor cells expressing the major early viral protein pp38 display reduced levels of BF. Thus, BF down-regulation begins in the immediate early phase and is complete by the early phase of viral gene expression. The intracellular pool of BF is not appreciably affected, indicating that the likely mechanism is a block in BF transport and not the result of transcriptional or translational regulation.

The complete unique long sequence and the overall genomic organization of the GA strain of Marek's disease virus

We have determined the DNA sequence of the unique long (UL) region and the repeat long (RL) region in the genome of serotype 1 GA strain of Marek's disease virus (MDV), a member of the alpha-herpesvirus family. With this information, the complete nucleotide sequence of GA-MDV is now known. The entire GA-MDV genome is predicted to be about 174 kbp in size, with an organization of TRL-UL-IRL-IRS-US-TRS, typical of a alpha-herpesvirus. The UL sequence contains 113,508 bp and has a base composition of 41.7% G + C. A total of 67 ORFs were identified completely within the UL region, among which 55 are homologous to genes encoded by herpes simplex virus-1. Twelve of them are unique with presently unknown functions. The sequence of RL reported here together with those published earlier reveal the major structural features of the RL. Virtually all of the ORFs encoded by RL are specific to serotype I of MDV. These ORFs are likely to contribute to some of the unique biological properties of MDV. Among the proteins encoded by MDV-specific ORFs are Meq, a jun/fos family of transcriptional factor implicated in transformation and latency, virus-encoded interleukin-8, a CXC chemokine, and pp38 and pp24, two phosphoproteins with undefined functions. There is also a putative lipase gene (LORF2) that has homologies in HPRS-24 (serotype II) strain of MDV and in various avian adenoviruses. An additional unique feature of MDV is the presence of long terminal repeat remnant sequences of avian retrovirus reticuloendotheliosis virus. These remnant sequences are derived from the U3-enhancer region through ancestral insertions by reticuloendotheliosis virus proviruses.

Paclitaxel up-regulates interleukin-8 synthesis in human lung carcinoma through an NF-kappaB- and AP-1-dependent mechanism

Lung cancer is a leading cause of cancer-related death in the United States. For this reason we chose to study the specific cellular effects that one chemotherapeutic agent, paclitaxel, has on lung carcinoma. In addition to its known mechanism of action, which is to stabilize microtubules, paclitaxel has been shown to have other interesting and relevant cellular effects. In this report, we demonstrate that a subset of human lung carcinoma cell lines respond to paclitaxel treatment with an up to a fivefold increase in the production of interleukin-8 (IL-8). We demonstrate that this increased production is specific to IL-8 but not to other chemokines, and is both dose- and time-dependent. Increased IL-8 mRNA is seen as early as 45 min with a peak at 4 h after paclitaxel treatment. This increase in mRNA is due to transcriptional activation because actinomycin D treatment blocked the increase. Paclitaxel also activates the mitogen-activated protein kinase family member, JNK1, in dose-dependent fashion. IL-8 enhancement is completely abolished with the use of an inhibitor of NF-kappaB, the super-repressor IkappaB. Similar results were obtained upon the inhibition of AP-1 activation with the MEK1/2 inhibitor, U0126. By gaining a better understanding of the differences in cellular response to paclitaxel chemotherapy, these findings might lead to either improved patient selection or to the development of adjuvant therapy targeted at specific-cell signaling proteins.

IL-8 reduced tumorigenicity of human ovarian cancer in vivo due to neutrophil infiltration

Paclitaxel is a frontline therapy for ovarian cancer. Our laboratory has shown that paclitaxel induces IL-8, a member of the C-X-C family of chemokines, in subsets of human ovarian cancer cells. However, the critical issue concerns the biological significance of this chemokine in human ovarian cancer. To study the influence of IL-8 on tumor growth, human ovarian cancer cell lines were transfected with an expression vector for human IL-8 and tested for their ability to form tumors in nude mice. IL-8 expression by the transfected cells did not alter their growth properties in vitro. In contrast, tumor growth in vivo was significantly attenuated in animals receiving IL-8-expressing cells when compared with mice injected with control cells. As additional evidence that IL-8 is a crucial factor in tumor growth, it was noted that ovarian cell lines in which constitutive IL-8 expression is elevated did not form tumors. Injection of neutralizing Ab to IL-8 reverted the phenotype and caused tumor growth in vivo. Examination of tissue from the inoculation site revealed a dramatically elevated cellularity, containing neutrophils and macrophages, in mice receiving IL-8-expressing tumor cells. These results suggest that IL-8 production by human ovarian tumor cells can play a role in reducing the rate of tumor growth; this effect may be mediated by the increased targeting of neutrophil and other mononuclear cells to the tumor injection site. These studies indicate a role for IL-8 in ovarian cancer control and suggest that chemotherapy-induced IL-8 may have a positive role in controlling tumor growth.

A genetically engineered cell line resistant to subgroup J avian leukosis virus infection (C/J)

A cell line (DF-1¿J) expressing the envelope protein isolated from the ADOL-Hc1 strain of the avian leukosis virus subgroup J (ALV-J) was used to analyze receptor interference to six different isolates of ALV-J as well as ALV subgroups A-D. The traditional gag-specific enzyme-linked immunosorbent assay (ELISA) as well as flow cytometry was used to evaluate viral infection. The parental cell line (DF-1) was susceptible to all ALV subgroups tested while the DF-1¿J cell line was selectively resistant to the subgroup J isolates. The DF-1¿J cell line was resistant to infection by all six ALV-J isolates as determined using the gag-specific ELISA. There was no interference with the other ALV subgroups (A-D) induced by the expression of the ADOL-Hcl envelope. The ALV-J isolates used in this analysis are serologically distinct when analyzed by flow cytometry. Convalescent sera to ADOL-Hcl cross-reacts with all of the ALV-J isolates tested; however, sera to HPRS-103 did not bind to four of the six isolates. Based on the intensity and differential binding of these antisera using flow cytometry, the six ALV-J isolates used can be grouped into four categories. Thus the DF-1¿J cell line is resistant to infection by a serologically and genetically diverse group of ALV-J isolates and should be useful as a diagnostic tool.

Relative reactivity of ribosyl 2'-OH vs. 3'-OH in concentrated aqueous solutions of phosphoimidazolide activated nucleotides

Phosphoimidazolide activated ribomononucleotides (*pN, see structure) are useful substrates for the non-enzymatic synthesis of oligonucleotides. In the presence of metal ions, aqueous solutions of *pN yield primarily the two internucleotide-linked (pN2' pN and pN3' pN) and the pyrophosphate-linked (N5' ppN) dimers. Small amounts of cyclic dimers and higher oligomers are also produced. In this study the relative reactivity of 2'-OH vs. 3'-OH was determined from the ratio of the yields of pN2' pN vs. pN3' pN. Experiments were performed at 23 degrees C in the range 7.2 < or = pH < or = 8.4 with substrates that differ in nucleobase (guanosine (G), cytidine (C), uridine (U), and adenosine (A)) and leaving group (imidazole (Im), 2-methylimidazole (2-MeIm) and 2,4-dimethylimidazole (2,4-diMeIm)). Two metal ions (Mg2+ or Mn2+) were employed as catalysts. The conditions used here, i.e. a substrate concentration in the range 0.1 M to 1.0 M and metal ion concentration in the range 0.05 M to 0.2 M, favor base-stacking interactions. The ratio pN2' pN: pN3' pN = 2'-5': 3'-5' was found independent of nucleobase and typically varied between 2 to 3 indicating that the 2'-OH is about 2 to 3 times more reactive than the 3'-OH. *pN with Im, compared to 2-MeIm and 2,4-diMeIm leaving group, produce lower yields of internucleotide linked dimers, and a higher pN2' pN: pN3' pN ratio. Trends in the data, observed with all three leaving groups, suggest an increase in pN2' pN: pN3' pN ratio with decreasing substrate concentration (up to 5.47 with 0.051 M ImpG). The observations are in accord with earlier studies reporting a relative reactivity 2'-5': 3'-5' = 6 to 9 obtained with Im as the leaving group, in dilute nucleotide solutions and under conditions that disfavor stacking. It is speculated that the concentration induced change in the relative reactivity is the result of self-association via base-stacking that enhances selectively the proximity of the 3'-OH of one molecule to the reactive P-N bond of an other molecule. The implication of these conclusions for oligomerization/ligation reactions is discussed.

Functional interactions between herpesvirus oncoprotein MEQ and cell cycle regulator CDK2

Marek's disease virus, an avian alphaherpesvirus, has been used as an excellent model to study herpesvirus oncogenesis. One of its potential oncogenes, MEQ, has been demonstrated to transform a rodent fibroblast cell line, Rat-2, in vitro by inducing morphological transformation and anchorage- and serum-independent growth and by protecting cells from apoptosis induced by tumor necrosis factor alpha, C2-ceramide, UV irradiation, or serum deprivation. In this report, we show that there is a cell cycle-dependent colocalization of MEQ protein and cyclin-dependent kinase 2 (CDK2) in coiled bodies and the nucleolar periphery during the G1/S boundary and early S phase. To our knowledge, this is the first demonstration that CDK2 is found to localize to coiled bodies. Such an in vivo association and possibly subsequent phosphorylation may result in the cytoplasmic translocation of MEQ protein. Indeed, MEQ is expressed in both the nucleus and the cytoplasm during the G1/S boundary and early S phase. In addition, we were able to show in vitro phosphorylation of MEQ by CDKs. We have mapped the CDK phosphorylation site of MEQ to be serine 42, a residue in the proximity of the bZIP domain. An indirect-immunofluorescence study of the MEQ S42D mutant, in which the CDK phosphorylation site was mutated to a charged residue, reveals more prominent cytoplasmic localization. This lends further support to the notion that the translocation of MEQ is regulated by phosphorylation. Furthermore, phosphorylation of MEQ by CDKs drastically reduces the DNA binding activity of MEQ, which may in part account for the lack of retention of MEQ oncoprotein in the nucleus. Interestingly, the localization of CDK2 in coiled bodies and the nucleolar periphery is observed only in MEQ-transformed Rat-2 cells, implicating MEQ in modifying the subcellular localization of CDK2. Taken together, our data suggest that there is a novel reciprocal modulation between the herpesvirus oncoprotein MEQ and CDK2.

Identification and characterization of glycoprotein H of MDV-1 GA strain

A 2439 bp open reading frame (ORF) was identified from the DNA sequence of BamHI-F and -K2 fragments of Marek's disease virus of serotype 1 (MDV-1) GA strain, which predicts an 813 amino acid polypeptide. This peptide is homologous to HSV-1 gH, and has typical glycoprotein features. There are nine potential N-linked glycosylation sites within the extracellular domain. A fragment of the gH ORF was cloned into pGEX vector in frame with glutathione S-transferase (GST) to produce a GST-gH fusion protein in Escherichia coli. The GST-gH fusion protein was used to develop gH monoclonal and polyclonal antibodies. Expression of gH was detected in duck embryo fibroblasts (DEFs) infected with MDV-1 GA strain by immunofluorescence assay (IFA) with these antibodies. Virus neutralization and plaque-forming inhibition analyses were conducted with the gH antiserum. There were no neutralization and plaque-forming inhibition activities of gH antiserum. Comparison of the DNA sequence of gH gene between GA and RB1B strains of MDV-1 revealed major difference in the upstream control elements of gH ORF.

Construction and characterization of a H19 epitope point mutant of MDV CVI988/Rispens strain

A recombinant virus, CVI/rpp38, was developed from the Marek's disease virus (MDV) CVI988/Rispens vaccine strain. This recombinant was obtained by transfection of CVI988/Rispens-infected chick embryo fibroblasts (CEFs) with plasmid pHA25 DNA containing pp38 gene from GA strain of MDV. Monoclonal antibody (MAb) H19 which reacts with pp38 from GA but not with that from CVI988 was used to screen for recombinant viruses in transfected cell culture plates by immunofluorescent assay (IFA). A positive plaque was isolated, propagated, and purified from cell-free virus particles after sonication of infected CEFs. The mutant CVI/rpp38 was not only reactive with MAb H19 in IFA but also in immunoprecipitation. A 38 kDa protein was immunoprecipitated from the CVI/rpp38 mutant virus but not from parental CVI988 virus. DNA sequence of the mutant virus showed a substitution of G at position 320 by a resulting in a change of an amino acid residue from arginine to glutamine. Comparison of nucleotide sequence of pp38 from strains GA, Md5 and Md11/75c/R2 and CVI988 revealed change to glutamine in this position. The result of this study provides a direct evidence for the location of the identified H19 epitope in pp38. This mutant is potentially useful to further explore the biological function of pp38 and its H19 epitope.

MEQ and V-IL8: cellular genes in disguise?

One of the hallmarks of oncogenic viruses is their ability to subvert the growth regulation and evade immune response of the host. There are a number of tricks devised by various virus families. Oncogenic herpesviruses often accomplish this by encoding homologs of cellular genes involved in these functions. These viral homologs sometimes are hyperactive forms of their cellular counterparts, which function to overtake the cellular pathways, other times serve as decoys to mask the cellular functions. Marek's disease virus (MDV) carries at least two genes in that category. We have previously described Meq protein (MEQ gene product), a transcriptional factor with homology to proto-oncogenes Jun and Fos in the bZIP domain. Meq dimerizes with Jun or Fos and the Meq/Jun heterodimer is able to transactivate promoters with AP-1 site. We show here that Meq and Jun colocalize in living cells, adding to the physiological significance of the dimer formation. In addition, we present data to show that Meq and Jun can functionally complement each other in cis and in trans, using transformation and transactivation assays. Finally we describe the discovery of an IL8 chemokine homolog, designated as v-IL8 (viral IL8) in the MDV genome and discuss its possible function in MDV infection.

Adult type anomalous origin of the left coronary artery from the main pulmonary artery: report of one case

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA syndrome) is a rare disease. Most of the cases suffer from myocardial infarction, congestive heart failure or even death during the early infantile period, and thus are called "infantile type". We present one five-year-old girl with ALCAPA syndrome, adult type, who was initially suspected to be a case of atypical Kawasaki disease (KD) complicated with coronary arterial aneurysms. Due to persistent dilatation of the coronary artery after medical treatment for one year and a turbulent flow noticed between the left coronary artery (LCA) and the main pulmonary artery (MPA), cardiac catheterization was arranged. The diagnosis was established from the coronary cineangiography in spite of a direct connection between the aorta and LCA revealed from the echocardiogram. Thereafter open heart surgery was undertaken. Diagnosis of ALCAPA syndrome can be made by echocardiogram, but this is not fully satisfactory. Selective coronary cineangiography remains the definitive diagnosis. Although the patients of adult type are more asymptomatic, surgical correction should be undertaken as soon as the diagnosis is established since a substantial risk is still present.

Paclitaxel (Taxol)-induced gene expression and cell death are both mediated by the activation of c-Jun NH2-terminal kinase (JNK/SAPK)

Paclitaxel (Taxol) is a novel anti-cancer drug that has shown efficacy toward several malignant tumors, particularly ovarian tumors. We reported previously that paclitaxel can induce interleukin (IL)-8 promoter activation in subgroups of ovarian cancer through the activation of both AP-1 and nuclear factor kappaB. Further analysis of paclitaxel analogs indicates that the degree of IL-8 induction by analysis correlates with the extent of cell death; however, IL-8 itself is not the cause of cell death. This suggests that pathways that lead to IL-8 and cell death may overlap, although IL-8 per se does not kill tumor cells. To decipher the upstream signals for paclitaxel-induced transcriptional activation and cell death, we studied the involvement of protein kinases that lead to the activation of AP-1, specifically the c-Jun NH2-terminal kinase (JNK1), p38, and the extracellular signal-regulated kinase 1 (ERK1). The role of IkappaB in paclitaxel-induced cell death was also analyzed. Paclitaxel activated JNK, and to a lesser degree p38, but not ERK1. Paclitaxel-induced IL-8 promoter activation was inhibited by dominant-inhibitory mutants of JNK, p38, and the super-repressor form of IkappaBalpha, but not by dominant-inhibitory forms of ERK1. Dominant-inhibitory mutants of JNK1 also greatly reduced paclitaxel-induced cell death, and the kinetics of JNK induction was closely followed by DNA fragmentation. These results indicate (i) that paclitaxel activates the JNK signaling pathway and (ii) that JNK activation is a common point of paclitaxel-induced gene induction and cell death.

Cytotoxic T lymphocyte response in chickens immunized with a recombinant fowlpox virus expressing Marek's disease herpesvirus glycoprotein B

Previously, we demonstrated that cytotoxic T lymphocytes (CTLs) from MHC: B19B19 and MHC: B21B21 chickens inoculated with a non-oncogenic Marek's disease virus (MDV) vaccine strain, SB-1/12 can lyse syngeneic reticuloendotheliosis virus (REV)-transformed cell lines expressing MDV pp38 or gB genes. In this study, we report the characterization of MDV gB-specific CTLs in chickens immunized with recombinant fowlpox virus expressing MDV gB gene (rFPV-gB). Spleen cells from rFPV-gB inoculated chickens (MHC: B19B19), depleted for CD4+, CD8+, TCR gamma delta+, TCR alpha beta 1+ or TCR alpha beta 2+ cells were used as effector cells in chromium release assays. Effector cells depleted of CD8+ or TCR alpha beta 1+, but not CD4+, TCR gamma delta+ or TCR alpha beta 2+ markedly reduced the percentage of specific release (%SR). Compared to the %SR caused by the SB-1/12-sensitized CTLs, the %SR caused by rFPV-gB-sensitized CTLs was low, but statistically significant. This is a first report on the induction of MDV gB-specific CD8+ CTLs in chickens immunized with rFPV-gB vaccine.