BCL-2-related protein expression in apoptosis: oxidative stress versus serum deprivation in PC12 cells

Expression of the BCL-2 protein family members, BAX, BAK, BAD, BCL-xL, BCL-xS, and BCL-2, was measured (by western blotting using specific antibodies) in PC12 cells before and during apoptosis induced by either H2O2 treatment or by serum deprivation and during rescue from apoptosis by nerve growth factor (NGF). H2O2-induced apoptosis, as measured by DNA fragmentation, caused: (a) a dose-dependent increase in BAX, (b) a dose-independent increase in BAK, and (c) a dose-dependent inhibition of BAD expression. By comparison, apoptosis induced by serum deprivation resulted in a time-dependent decrease in both BAX and BAK, along with a dramatic and sudden decrease in BAD expression. However, when PC12 cells were incubated in an apoptosis-sparing medium (i.e., NGF-supplemented serum-free medium), both BAX and BAK were increased significantly, whereas BAD expression remained inhibited. BCL-xL expression was increased by H2O2 but unaffected by serum deprivation or long-term NGF treatment. Neither BCL-2 nor BCL-xS expression could be detected in PC12 cells under the experimental conditions tested. Our results show that the expression of BAX, BAK, BAD, and BCL-xL is altered in a stimulus-dependent manner but cannot be used to define whether a cell will undergo or survive apoptosis. The similarity between changes in expression of BCL-2-related proteins induced by H2O2 exposure and NGF rescue could reflect activation in part of a common antioxidant pathway.     

BID: a novel BH3 domain-only death agonist

The BCL-2 family of proteins consists of both antagonists (e.g., BCL-2) and agonists (e.g., BAX) that regulate apoptosis and compete through dimerization. The BH1 and BH2 domains of BCL-2 are required to heterodimerize with BAX and to repress cell death; conversely, the BH3 domain of BAX is required to heterodimerize with BCL-2 and to promote cell death. To extend this pathway, we used interactive cloning to identify Bid, which encodes a novel death agonist that heterodimerizes with either agonists (BAX) or antagonists (BCL-2). BID possesses only the BH3 domain, lacks a carboxy-terminal signal-anchor segment, and is found in both cytosolic and membrane locations. BID counters the protective effect of BCL-2. Moreover, expression of BID, without another death stimulus, induces ICE-like proteases and apoptosis. Mutagenesis revealed that an intact BH3 domain of BID was required to bind the BH1 domain of either BCL-2 or BAX. A BH3 mutant of BID that still heterodimerized with BCL-2 failed to promote apoptosis, dissociating these activities. In contrast, the only BID BH3 mutant that retained death promoting activity interacted with BAX, but not BCL-2. This BH3-only molecule supports BH3 as a death domain and favors a model in which BID represents a death ligand for the membrane-bound receptor BAX.     

Varicella. Universal immunization or selective?

BAX, a heterodimer partner of BCL-2, is an apoptosis inducer. We aimed to characterize the distribution of the BAX protein in normal adult human tissues using immunohistochemistry (IHC). The monoclonal antibody anti-BAX 4F11 was used on paraffin sections: immunodetection of BCL-2 was performed simultaneously on serial sections. The specificity of BAX IHC staining was verified by Western blot analysis. IHC positivity was correlated with the detection of a specific 21 kDa band on Western blots. BAX immunostaining was mainly cytosolic and occasionally on the nuclear membrane. Amounts of BAX protein were high in liver, renal tubules, endocrine islets of the pancreas, gastric glands, cardiac muscle, epididymis, lymph node germinal centers, and neurons; intermediate in the colon, stomach, bronchus. Fallopian tube, salivary gland, breast, thymus, spleen, and testis; low or undetectable in the other tissues. BAX IHC positivity correlated with apoptotic features in neurons and germinal center lymphocytes. There was no strict correlation between the IHC profiles of BAX and BCL-2 expression, although a reciprocal pattern of staining was observed in lymph node and colon. This report shows the usefulness the monoclonal antibody anti-BAX 4F11 on paraffin sections and demonstrates that the human BAX tissular distribution is close to, but not similar, to the profile observed in the mouse. The widespread BAX expression suggests that BAX alone is insufficient to trigger cell death in human tissues. BAX may either modulate the role of other regulators of apoptosis or carry out functions unrelated to apoptosis.     

Treatment of anemia in myelodysplastic syndromes with granulocyte colony-stimulating factor plus erythropoietin: results from a randomized phase II study and long-term follow-up of 71 patients

Malignant gliomas are rather refractory to current therapeutic approaches including surgery, radiotherapy, chemotherapy and immunotherapy. Acquired alterations in the pathways required for apoptotic cell death are thought to be responsible to the failure of glioma to respond to therapy. Here we have examined the expression of several proteins involved in the susceptibility to apoptosis in 20 human gliomas, including the BCL-2 family proteins BCL-2, BCL-X, BAX and MCL-1, as well as p53 and RB. Most gliomas expressed several BCL-2 family proteins. There was good correlation between expression of the functional antagonists, BCL-2/BCL-X and BAX, suggesting that changes in the BCL-2+BCL-X/BAX ratio are not responsible for the differential response of glioma patients to chemotherapy. The immunochemistry data were also analysed in regard to response to therapy and clinical outcome. All patients had cytoreductive surgery and received radiotherapy and nitrosourea-based adjuvant chemotherapy. There was no prominent association of outcome with the expression patterns of p53, RB, BCL-2, BCL-X or BAX. We find, however, that expression of the MCL-1 protein is associated with early tumour recurrence and shorter survival in this group of glioma patients. This preliminary observation will have to be confirmed in a larger independent sample of glioma patients.     

The cancer growth suppressor gene mda-7 selectively induces apoptosis in human breast cancer cells and inhibits tumor growth in nude mice

A differentiation induction subtraction hybridization strategy is being used to identify and clone genes involved in growth control and terminal differentiation in human cancer cells. This scheme identified melanoma differentiation associated gene-7 (mda-7), whose expression is up-regulated as a consequence of terminal differentiation in human melanoma cells. Forced expression of mda-7 is growth inhibitory toward diverse human tumor cells. The present studies elucidate the mechanism by which mda-7 selectively suppresses the growth of human breast cancer cells and the consequence of ectopic expression of mda-7 on human breast tumor formation in vivo in nude mice. Infection of wild-type, mutant, and null p53 human breast cancer cells with a recombinant type 5 adenovirus expressing mda-7, Ad.mda-7 S, inhibited growth and induced programmed cell death (apoptosis). Induction of apoptosis correlated with an increase in BAX protein, an established inducer of programmed cell death, and an increase in the ratio of BAX to BCL-2, an established inhibitor of apoptosis. Infection of breast carcinoma cells with Ad.mda-7 S before injection into nude mice inhibited tumor development. In contrast, ectopic expression of mda-7 did not significantly alter cell cycle kinetics, growth rate, or survival in normal human mammary epithelial cells. These data suggest that mda-7 induces its selective anticancer properties in human breast carcinoma cells by promoting apoptosis that occurs independent of p53 status. On the basis of its selective anticancer inhibitory activity and its direct antitumor effects, mda-7 may represent a new class of cancer suppressor genes that could prove useful for the targeted therapy of human cancer.     

Hematopoietic malignancies demonstrate loss-of-function mutations of BAX

The BCL-2 gene family regulates the susceptibility to apoptotic cell death in many cell types during embryonic development and normal tissue homeostasis. Deregulated expression of anti-apoptotic BCL-2 can be a primary aberration that promotes malignancy and also confers resistance to chemotherapeutic agents. Recently, studies of Bax-deficient mice have indicated that the pro-apoptotic BAX molecule can function as a tumor suppressor. Consequently, we examined human hematopoietic malignancies and found that approximately 21% of lines possessed mutations in BAX, perhaps most commonly in the acute lymphoblastic leukemia subset. Approximately half were nucleotide insertions or deletions within a deoxyguanosine (G8) tract, resulting in a proximal frame shift and loss of immunodetectable BAX protein. Other BAX mutants bore single amino acid substitutions within BH1 or BH3 domains, demonstrated altered patterns of protein dimerization, and had lost death-promoting activity. Thus, mutations in the pro-apoptotic molecule BAX that confer resistance to apoptosis are also found in malignancies.     

Complete dorsal dislocation of the metacarpophalangeal joint of the thumb

Recent studies using animal models of congenital diaphragmatic hernia (CDH) have reported a reduction in both surfactant (SF) phospholipids and proteins in CDH lungs compared to controls, resulting in biophysical and physiologic impairment of SF function in the hypoplastic CDH lung. Furthermore, SF replacement has been shown to improve physiological function in CDH lungs. Tumor necrosis factor-alpha (TNF-alpha) is a polypeptide whose overproduction has been implicated in the pathogenesis of a number of pathological conditions, such as neonatal and adult respiratory distress syndrome. TNF-alpha has been shown to selectively inhibit the de-novo synthesis of SF phospholipid components in type II pneumocytes. It has been demonstrated that TNF-alpha is synthesized locally in lung and functions in an autocrine/paracrine mode. The aim of this study was to investigate TNF-alpha messenger RNA (mRNA) expression in hypoplastic CDH lung using in-situ hybridization histochemistry, to determine the molecular basis of the SF deficiency in the hypoplastic CDH lung. Lung-tissue samples were obtained at autopsy from 7 full-term newborns (age range: 1-21 days) with CDH and 4 stillborns with CDH. Normal lung tissue from eight infants with sudden infant death syndrome (age range: 5-30 days) acted as controls. In-situ hybridization was performed using TNF-alpha specific and digoxigenin-labeled oligonucleotide probe and visualized by nitroblue tetrazolium staining. In control lung tissue, mRNA expression of TNF-alpha was absent or weak in type II pneumocytes and alveolar macrophages. In contrast, mRNA expression of TNF-alpha was markedly increased in both type II pneumocytes and alveolar macrophages in hypoplastic CDH lung. Our findings of up-regulated TNF-alpha gene expression in CDH lung suggest that the SF deficiency observed in hypoplastic CDH lung may be the result of increased local production of TNF-alpha.     

Fos expression in rat pontine tegmental neurons following activation of the medial preoptic area

Because murine myeloma plasma cells and normal human lymph node plasma cells express BCL-X, we evaluated BCL-X expression in malignant human plasma cells. BCL-X expression was detected in several human myeloma cell lines, as well as in CD38-sorted bone marrow cells obtained from some patients. Only the antiapoptotic long form of BCL-X (BCL-X-L), was detected. Because BCL-X-L expression can protect tumor cells from apoptotic death induced by chemotherapeutic agents, we tested the clinical relevance of expression in 55 archival bone marrow biopsies. The biopsies were stained by immunohistochemistry, and BCL-X expression was correlated with the subsequent response to treatment. BCL-X expression in malignant plasma cells strongly correlated with decreased response rates in patient groups treated with either melphalan and prednisone or vincristine, Adriamycin, and dexamethasone. Response rates were 83-87% in non-BCL-X-expressing cases and 20-31% in BCL-X-expressing cases. In addition, BCL-X expression was more frequent in specimens taken from patients at relapse (77%), when compared to those at initial diagnosis (29%). Further support for the association of drug resistance with BCL-X-L expression came from studies of the 8226 dox-40 cell line. This line, which expresses p-glycoprotein and serves as a model of multidrug resistance in multiple myeloma cells, demonstrated an up-regulated expression of BCL-X-L, which was relatively specific, in that BCL-2 or BAX expression was not altered. In addition, dox-40 cells demonstrated a generalized resistance to apoptosis that was induced by several different agents. These results indicate that malignant plasma cells can express BCL-X-L and that such expression may be a marker of chemoresistant disease.     

Loss of EDB+ fibronectin isoform is associated with differentiation of alveolar epithelial cells in human fetal lung

Cell-matrix interactions have been shown to regulate the development of the lung, particularly airway branching and alveolarization. Fibronectin is the major constituent of pulmonary extracellular matrix and exists in multiple isoforms arising from alternative RNA splicing. EDA and EDB are the two major alternatively spliced segments, the expression of which is regulated in a spatiotemporal and oncodevelopmental manner. In this study, we investigated immunohistochemically the distribution of the EDA- and EDB-containing fibronectin isoforms (referred to as EDA+ fibronectin and EDB+ fibronectin, respectively) in normal and hypoplastic human lungs at different gestational ages to explore the role of these fibronectin isoforms in alveolarization. EDA+ fibronectin was expressed around the distal airspaces throughout the development of both normal and hypoplastic lungs. In contrast, the expression of EDB+ fibronectin was restricted to the lung with morphologically immature acinar complex, typically observed in normally developing lungs of < 30 gestational weeks or in hypoplastic lungs. To further confirm the restricted expression of EDB+ fibronectin in immature acinar complex, we examined the correlation of EDB+ fibronectin expression with that of the surfactant protein SP-A, a biochemical marker for the differentiated type II pneumocytes. A clear inverse relationship between the immunoreactivities for EDB+ fibronectin and SP-A was observed in both control and hypoplastic lungs. Given the proposed importance of fibronectins in the differentiation of alveolar epithelial cells, our results suggest that the EDB segment plays a regulatory role in the differentiation of immature acinar epithelial cells into type II pneumocytes. The EDB segment may also serve as a new histochemical marker for the functional maturity of fetal lung tissues.     

Smoke extract stimulates lung epithelial cells to release neutrophil and monocyte chemotactic activity

Inflammatory cells accumulate within the lungs of cigarette smokers. Current concepts suggest that these cells can induce protease-antiprotease and/or oxidant-antioxidant imbalance(s), which may damage the normal lung alveolar and interstitial structures. Because type II pneumocytes line the alveolar space, and because the inflammatory cells migrate and reside at the alveolus, we postulated that the type II pneumocytes might release chemotactic activity for neutrophils and monocytes in response to smoke extract. To test this hypothesis, A549 cells were cultured and the supernatant fluids were evaluated for the neutrophil and monocyte chemotactic activity (NCA and MCA) by a blind-well chamber technique. A549 cells released NCA and MCA in response to smoke extract in a dose- and time-dependent manner (P < 0.05). Checkerboard analysis showed that the activity was chemotactic. Partial characterization of NCA and MCA revealed that the activity was partly heat labile, trypsin sensitive, and ethyl acetate extractable. Lipoxygenase inhibitors and cycloheximide inhibited the release of NCA and MCA. Molecular sieve column chromatography showed multiple peaks for both NCA and MCA. NCA was inhibited by anti-human-interleukin (IL)-8 antibody, granulocyte colony-stimulating factor (G-CSF) antibody, or leukotriene (LT)B4 receptor antagonist. Monocyte chemoattractant protein (MCP)-1 antibody or LTB4 receptor antagonist inhibited MCA. Immunoreactive IL-8, G-CSF, MCP-1, and LTB4 significantly increased in the supernatant fluids in response to smoke extract. These data suggest that the type II pneumocytes may release NCA and MCA and modulate the inflammatory cell recruitment into the lung.     

BAX frameshift mutations in cell lines derived from human haemopoietic malignancies are associated with resistance to apoptosis and microsatellite instability

Bax suppresses tumorigenesis in a mouse model system and Bax-deficient mice exhibit lymphoid hyperplasia suggesting that BAX functions as a tumour suppressor in human haemopoietic cells. We examined BAX expression in 20 cell lines derived from human haemopoietic malignancies and consistent with a potential tumour suppressor function, identified two cell lines, DG75 (a Burkitt lymphoma cell line) and Jurkat (a T-cell leukaemia line), which lacked detectable BAX expression. Apoptosis of DG75 cells induced by low serum or ionomycin was significantly delayed relative to similar Burkitt lymphoma cell lines with normal BAX levels. Although DG75 and Jurkat cells expressed several BAX RNA species including the prototypical BAX alpha RNA, the absence of BAX protein was due to single base deletions and additions in a polyguanine tract within the BAX open reading frame. These frameshift mutations result in premature termination of translation and have recently also been identified in some colon cancers with microsatellite instability. Although mismatch repair defects are not considered a common feature of haemopoietic malignancies, DG75 and Jurkat cells had widespread microsatellite instability and did not express detectable levels of MSH2. In Jurkat cells, lack of MSH2 expression was due to a point mutation in exon 13 of MSH2 resulting in premature termination of translation. Our results suggest that a pathway linking mismatch repair defects, BAX tumour suppressor frameshift mutations and resistance to apoptosis may be a key feature of some lymphomas and leukaemias.     

Potentiation of CD95L-induced apoptosis of human malignant glioma cells by topotecan involves inhibition of RNA synthesis but not changes in CD95 or CD95L protein expression

Topotecan is a novel topoisomerase I inhibitor that may have a role in the adjuvant chemotherapy of several solid tumors, including malignant glioma. Here, we have characterized the time- and concentration-dependent toxicity of topotecan in four human malignant glioma cell lines, LN-18, LN-229, LN-308 and T98G. High micromolar concentrations of topotecan, which are unlikely to be achieved in plasma in human patients in vivo, were cytotoxic within 48 hr, induced DNA fragmentation, did not induce major cell cycle changes, failed to consistently alter BCL-2 or BAX protein levels but inhibited RNA synthesis and induced cleavable DNA/topoisomerase I complex formation. Prolonged exposure for 72 hr to high nanomolar to low micromolar concentrations of topotecan augmented p21 protein levels and induced G2/M arrest but failed to consistently alter BCL-2 and BAX protein levels, did not induce significant DNA/topoisomerase I complex formation and did not inhibit RNA synthesis. Neither short-term nor long-term topotecan toxicity was blocked by ectopic expression of bcl-2 or wild-type p53. Transfer of a mutant p53 gene enhanced topotecan sensitivity in wild-type p53 LN-229 but not mutant p53 LN-18 cells. CD95 ligand (CD95L)-induced apoptosis was synergistically enhanced by short-term/high concentration but not long-term/low concentration exposure to topotecan, suggesting that topotecan sensitizes human malignant glioma cells to CD95L-induced apoptosis via inhibition of RNA synthesis. These data suggest that topotecan needs to be administered in high concentrations, such as an intratumoral polymer, to limit glioma cell growth in synergy with CD95L in vivo.     

Neutrophil migration through preexisting holes in the basal laminae of alveolar capillaries and epithelium during streptococcal pneumonia

The purpose of this study was to determine whether or not there are preexisting holes in the endothelial and epithelial basal laminae of alveolar walls and to determine the path taken by neutrophils as they migrate from the capillaries to the airspace of the alveoli during inflammation. Using transmission electron microscopy and serial thin sections of normal rabbit and mouse lung, we have demonstrated the presence of slit-like holes in the capillary basal laminae and round holes in the basal laminae of type 2 pneumocytes. The slits in the capillary basal laminae were observed at the intersection of the thick and thin walls where endothelium, pericytes, and fibroblasts make close contact. The round holes in the type 2 cell basal laminae were observed at sites of close contact with fibroblasts. Neutrophils were observed to migrate through these slits and holes during streptococcal pneumonia in rabbit lungs. We conclude that during inflammation in the lung, migrating neutrophils displace pericytes and fibroblasts from the slits in the capillary basal lamina and then crawl through these slits into the alveolar interstitium. We postulate that neutrophils find their way to type 2 pneumocytes by following interstitial fibroblasts. We believe that neutrophils displace fibroblasts from their close contacts with the type 2 cells and then crawl through the holes in the basal lamina into the basal lateral space of the type 2 cells. From there, neutrophils migrate into the alveolar airspace.     

Mutagenesis of the BH3 domain of BAX identifies residues critical for dimerization and killing

The BCL-2 family of proteins is comprised of proapoptotic as well as antiapoptotic members (S. N. Farrow and R. Brown, Curr. Opin. Genet. Dev. 6:45-49, 1996). A prominent death agonist, BAX, forms homodimers and heterodimerizes with multiple antiapoptotic members. Death agonists have an amphipathic alpha helix, called BH3; however, the initial assessment of BH3 in BAX has yielded conflicting results. Our BAX deletion constructs and minimal domain constructs indicated that the BH3 domain was required for BAX homodimerization and heterodimerization with BCL-2, BCL-XL, and MCL-1. An extensive site-directed mutagenesis of BH3 revealed that substitutions along the hydrophobic face of BH3, especially charged substitutions, had the greatest affects on dimerization patterns and death agonist activity. Particularly instructive was the BAX mutant mIII-1 (L63A, G67A, L70A, and M74A), which replaced the hydrophobic face of BH3 with alanines, preserving its amphipathic nature. BAXmIII-1 failed to form heterodimers or homodimers by yeast two-hybrid or immunoprecipitation analysis yet retained proapoptotic activity. This suggests that BAX's killing function reflects mechanisms beyond its binding to BCL-2 or BCL-XL to inhibit them or simply displace other protein partners. Notably, BAXmIII-1 was found predominantly in mitochondrial membranes, where it was homodimerized as assessed by homobifunctional cross-linkers. This characteristic of BAXmIII-1 correlates with its capacity to induce mitochondrial dysfunction, caspase activation, and apoptosis. These data are consistent with a model in which BAX death agonist activity may require an intramembranous conformation of this molecule that is not assessed accurately by classic binding assays.     

Evidence against a direct role for the induction of c-jun expression in the mediation of drug-induced apoptosis in human acute leukemia cells

Previous reports have demonstrated that a variety of anticancer drugs, e.g., 1-beta-D-arabinofuranosylcytosine (ara-C), mitoxantrone, etoposide, camptothecin, and cisplatin, induce the expression of c-jun oncogene in leukemic cells prior to producing internucleosomal DNA fragmentation and the morphological features of apoptosis. This has led to the impression that the induction of c-jun expression may be directly involved in the molecular signaling of the final common pathway of programmed cell death or apoptosis. In the present study, we examined the role of c-jun expression in three different settings of anticancer drug-induced apoptosis in human leukemic cells. First, exposure of human myeloid leukemia HL-60 cells to high-dose ara-C for 4 h produced internucleosomal DNA fragmentation preceded by c-jun induction. However, pretreatment of HL-60 cells with staurosporine, a protein kinase C inhibitor, repressed c-jun yet enhanced DNA fragmentation and apoptosis due to ara-C. Second, in human pre-B leukemia 697/BCL-2 cells which are transfected with the cDNA of the bcl-2 oncogene and overexpress p26BCL-2, although ara-C or mitoxantrone treatment caused greater c-jun induction than in the 697/neo cells, significantly reduced endonucleolytic DNA fragmentation and apoptosis was observed in 697/BCL-2 cells. Finally, taxol-induced internucleosomal DNA fragmentation and morphological features of apoptosis in HL-60 cells were not associated with the induction of c-jun expression. These lines of evidence indicate that the induction of c-jun expression may not have a direct role in the molecular signaling of anticancer drug-induced apoptosis, and that the anticancer drug-induced apoptosis can occur by a mechanism that does not involve the induction of c-jun expression.     

Gemcitabine cytotoxicity of human malignant glioma cells: modulation by antioxidants, BCL-2 and dexamethasone

Gemcitabine is a novel antimetabolite drug that acts by multiple mechanisms, including inhibition of ribonucleoside diphosphate reductase, of dCMP deaminase and of dCTP incorporation into DNA and RNA. Here, we report that gemcitabine induces cytotoxic and clonogenic death of 12 human malignant glioma cell lines at clinically relevant concentrations around 1 microM. Gemcitabine is thus approximately 100-fold more active than the congener drug, cytarabine. Gemcitabine cytotoxicity of glioma cells does not require wild-type p53 activity: (i) there was no difference in the susceptibility to gemcitabine between cell lines with wild-type p53 and cell lines with mutant or deleted p53; (ii) ectopic expression of a temperature-sensitive p53 protein either at wild-type (32.5 degrees C) or at mutant (38.5 degrees C) conformation had no significant influence on gemcitabine-induced cell death. Gemcitabine cytotoxicity was unaffected by the antioxidants, N-acetylcysteine and phenyl-N-tert-butyl-alpha-phenylnitrone. There was no correlation between the susceptibility to gemcitabine and the endogenous expression of the B cell lymphoma-2 (BCL-2)-family proteins BCL-2, BCL-XL, myeloid cell leukemia-1 (MCL-1), BCL-2-associated X protein (BAX), BCL-2 homologous antagonist/killer (BAK) and BCL-XS. Ectopic expression of BCL-2 moderately attenuated gemcitabine-induced cell death. Similarly, preexposure to the synthetic steroid, dexamethasone, which is commonly used to control cerebral edema in brain tumor patients, reduced gemcitabine cytotoxicity. We conclude that the clinical evaluation of gemcitabine for the adjuvant chemotherapy of malignant glioma is warranted.     

A monoclonal antibody pool for routine immunohistochemical detection of human respiratory syncytial virus antigens in formalin-fixed, paraffin-embedded tissue

Four monoclonal antibodies (MAbs) with specificities for epitopes on human respiratory syncytial virus (RSV) proteins preserved after formalin fixation and paraffin embedding were identified in fixed and embedded virus-infected HEp-2 cell pellets. The MAbs bound epitopes on the fusion protein, the nucleoprotein, the phosphoprotein, and the M2 protein of the virus. Following high-temperature antigen unmasking, immunohistochemical staining revealed RSV antigens in the lungs of five of seven children who died with confirmed RSV infection and in none of nine children who died for other reasons, with no evidence of RSV infection. Staining was cytoplasmic, granular, and confined to epithelial cells. Intense staining was seen at the apex of ciliated bronchial and bronchiolar epithelial cells in all five positive cases. In one case, of pneumonitis, infected pneumocytes were present in the alveoli and in several cases, CD68-positive, cytokeratin-negative alveolar macrophages stained for viral antigens. These antibodies may prove useful in studies of the pathogenesis of RSV infection.     

A potent cell death activity associated with transient high level expression of BCL-2

The BCL-2 proto-oncogene contains unusually long untranslated 5' and 3' sequences. Deletion of the sequences flanking the BCL-2 open reading frame dramatically increases the level of protein expression. Transient high level BCL-2 protein expression mediated by plasmid transfection or by infection with recombinant adenovirus results in potent apoptosis of several cell lines. Detailed mutational (deletion and add-back) analysis reveals that both 5'- and 3'-flanking sequences contribute to the negative modulation of protein expression from the BCL-2 open reading frame. It appears that these sequences exert the negative regulatory effect in an orientation-dependent manner. Analysis of BCL-2 RNA levels indicate that elevated levels of mRNA may be the primary cause of elevated levels of protein expression. Apoptosis induced by adenovirus vectors expressing elevated levels of BCL-2 can be readily inhibited by the caspase inhibitor z-VAD-fmk, suggesting that high levels of BCL-2 expression induce apoptosis via the caspase cascade. Mutational analysis of BCL-2 indicates that its pro-apoptotic activity is separable from its anti-apoptosis activity. Our results raise the possibility that oncogenic conversion of BCL-2 may require somatic mutations in the pro-apoptotic activity, in addition to other activating mutations that result in enhanced expression. Consistent with this hypothesis, a somatic mutation of BCL-2 observed in multiple human tumors results in reduced apoptosis activity.     

Expression of ICAM-1, VCAM-1, and LFA-1 in adenocarcinoma of the lung with observations on the expression of these adhesion molecules in non-neoplastic lung tissue

Intercellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), and the lymphocyte function-associated antigen (LFA-1) are cell adhesion molecules thought to play an important role in the complex process of airway inflammation and tumor cell growth. The aim of this study was to examine the distribution of ICAM-1, VCAM-1, and LFA-1 in adenocarcinoma of lung and in major cellular compartments of non-neoplastic lung tissue. We examined cellular compartments in tissue from five bronchoalveolar carcinomas, three acinar adenocarcinomas, and one colon cancer metastatic to the lung. The compartments in neoplasms included the tumor cells proper, endothelial cells within the tumor vasculature, tumor stromal cells, and tumor-infiltrating lymphocytes. The compartments in non-neoplastic lung tissue included lung endothelial cells, pulmonary lymphocytes, interstitial fibroblasts, Type II alveolar pneumocytes, and bronchial epithelial cells. ICAM-1 was expressed in tumor cells from all of the nine adenocarcinomas. In contrast, VCAM-1 expression was not identified in tumor cells from any of the nine adenocarcinomas. ICAM-1 was expressed in all cellular compartments of the non-neoplastic lung tissue, whereas VCAM-1 was expressed only in pulmonary lymphocytes and interstitial fibroblastic cells. LFA-1 was uniformly expressed in tumor-infiltrating lymphocytes from each of the nine tumors and all of the lymphocytes in non-neoplastic lung tissue. This study showed major differences in the expression of ICAM-1 and VCAM-1 in tumor cells from pulmonary adenocarcinoma and also provided evidence for a wider distribution of ICAM-1, compared with VCAM-1, in non-neoplastic cellular compartments of the lung. ICAM-1 expression was particularly noticeable in bronchial and alveolar epithelial cells. Upregulation of ICAM-1 in pulmonary adenocarcinoma might foster binding by LFA-1-bearing lymphocytes, with a possible impact on the vulnerability of tumor cells to host defense mechanisms.