Proliferation and apoptosis within juvenile capillary hemangiomas

Capillary hemangiomas (CH) are benign vascular neoplasms of childhood that undergo a natural course of postnatal growth followed by spontaneous involution and often complete regression. There are currently no established standards for the identification of the growth phase of CH. We retrospectively examined 24 CH specimens for staining with MIB1, a monoclonal antibody directed at the same proliferation-related antigen as Ki-67, and antibody to bcl-2, a protooncogene product associated with inhibition of cellular apoptosis, and correlated these findings with the growth phase. All lesions demonstrated more positively with MIB1 than with bcl-2, with more prominent staining in interstitial cells and an inverse correlation with increasing age. When calculations were adjusted for vascular lumina predominance, staining similarly decreased but at a later age. Our study supports interstitial cell-predominant proliferation within CH. In addition, bcl-2 expression was demonstrated, also interstitially predominant, and showed a decrease with aging, suggesting that programmed cellular death is involved in the growth regulation of these lesions and that regression is associated with changes in both proliferation and apoptosis. Last, both proliferation and bcl-2 expression showed a marked decrease later in more vascular channel-predominant lesions, possibly suggesting that such lesions undergo longer periods of growth before entering the involutional phase.

Bcl-2 sensitivity differentiates two pathways for motoneuronal death in the wobbler mutant mouse

The molecular events leading to motoneuronal death are still poorly understood. In mammals, the bcl-2 proto-oncogene, which encodes a membrane-associated protein, has been shown to suppress both developmental motoneuronal death and experimental axotomy-induced motoneuronal death. We assessed a potential protective effect of Bcl-2 on pathological motoneuronal death processes in adult rodents. We took advantage of the murine mutant wobbler, which undergoes progressive degeneration of the spinal and brainstem motoneurons. A hybrid carrying both the wobbler mutation and the human bcl-2 transgene under the control of the neuron-specific enolase promoter was produced. Although Bcl-2 protected spinal and brainstem motoneurons from developmental death and the postnatal motoneurons of the facial nucleus from axotomy-induced death, the pathological motoneuronal death was not altered in the adult hybrid. These results demonstrate that Bcl-2 sensitivity distinguishes at least two different motoneuronal death pathways in the wobbler mutant. They support the hypothesis that experimental and pathological motoneuronal death are dependent on different cellular mechanisms.

Effect of N-(4-hydroxyphenyl)retinamide on apoptosis in human breast cancer cells

The synthetic retinoid N-(4-hydroxyphenyl)retinamide (4-HPR) has been used in breast cancer prevention and treatment. However, the molecular mechanisms mediating the effects of 4-HPR remain elusive. In the present study, we examined the effects of 4-HPR on components of apoptosis pathway (i.e Bcl-2 and Bax) and apoptotic death in both estrogen receptor-positive and estrogen receptor-negative cell lines. We found that: (1) 4-HPR treatment resulted in decreased Bcl-2 mRNA but not Bax mRNA levels; (2) the effect of 4-HPR on Bcl-2 mRNA level was different from other retinoids; (3) 4-HPR treatment induced apoptosis in both estrogen receptor-positive and -negative cells. Hence, the breast cancer chemopreventive properties of 4-HPR may involve modulation of apoptosis pathways.

Apoptosis induced by inhibitors of the plasma membrane NADH-oxidase involves Bcl-2 and calcineurin

Activation of the plasma membrane NADH-oxidoreductase (PMOR) system by addition of growth factors or extracellular electron acceptors stimulates cellular proliferation. We now show that the vanilloids capsaicin, dihydrocapsaicin, and resiniferatoxin are inhibitors of the NADH-oxidase activity of the PMOR system and that both these and two previously identified PMOR inhibitors (chloroquine and retinoic acid) induce apoptosis in human B-cell and mouse myeloid cell lines. At the optimal concentration, PMOR inhibitors can induce between 50 and 70% of apoptosis in mouse myeloid and human B-cell lines within 8-12 h, provided these cell lines do not express Bcl-2. The immunosuppressants cyclosporin A and fujimycin (tacrolimus) inhibit PMOR inhibitor-induced apoptosis. By using combinations of these immunosuppressants and excess amounts of their nonimmunosuppressive analogues, we demonstrate that in human B-cell lines the Bcl-2-sensitive apoptotic pathway triggered by PMOR inhibitors involves signaling through the protein phosphatase calcineurin. We suggest that the PMOR system is a redox sensor that can, depending on the ambient redox environment and the availability of growth factors, regulate plasma membrane calcium fluxes and signal for apoptosis through calcineurin. Bcl-2, a protein that is thought to inhibit apoptosis by regulating reactive oxygen species and calcium fluxes in the cell, inhibits this apoptotic pathway.

C-Myc and Bcl-2 protein expression during the induction of apoptosis and differentiation in TNF alpha-treated HL-60 cells

We examined c-Myc and Bcl-2 protein expressions during the induction of apoptosis and differentiation in TNF alpha-treated HL-60 cells using a two-color flow cytometric method. We found that c-Myc protein was rapidly down-regulated in the apoptotic cells while Bcl-2 protein was expressed at relatively high levels. Concomitantly with terminal differentiation Bcl-2 protein was down-regulated in differentiating cells as well as c-Myc protein. We also showed that c-myc antisense oligonucleotides could induce apoptosis in HL-60 cells whereas bcl-2 antisense did not induce apoptosis during the early time of treatment. These results suggest that the down-regulation of c-Myc protein expression is a primary event to induce apoptosis and neither consistent expression of c-Myc protein nor rapid down-regulation of Bcl-2 protein is necessary for the initial processing of apoptosis in HL-60 cells. Furthermore, concomitant down-regulation of c-Myc and Bcl-2 is closely associated with terminal differentiation and apoptotic cell death of HL-60 cells treated with TNF alpha.

Adenovirus E1B 19-kDa death suppressor protein interacts with Bax but not with Bad

Adenovirus E1B 19-kDa protein (19K) is a member of the Bcl-2 family of suppressors of apoptosis. The suppressors function through heterodimerization with the death promoters, Bax and related proteins, thus establishing a set point within the cell that determines whether or not apoptosis is executed in response to a death signal. Sequence similarities between 19K and Bcl-2 are largely restricted to short Bcl-2 homology (BH) domains that mediate interaction with Bax. The BH1 sequence in 19K is degenerate but nevertheless contains a conserved glycine residue found in all family members that when mutated to alanine in Bcl-2 results in loss of Bcl-2 function and ability to dimerize with Bax (Yin, X.-M., Oltvai, Z. N., and Korsmeyer, S. J. (1994) Nature 369, 321-323). Here, we show that the analogous mutation in BH1 of 19K also abrogates the anti-apoptotic properties of 19K and its ability to interact with Bax, thus establishing the critical importance of this residue within BH1 and the likely similarity of Bcl-2 and 19K function. In distinct contrast to Bcl-2, however, 19K interaction was not detected with Bad, a Bcl-2/Bcl-XL dimerizing protein that can potentially regulate a Bax middle dotBcl-2/Bcl-XL survival set point and reinstate susceptibility to a death signal. Furthermore, the anti-apoptotic function of 19K was not overcome by enforced expression of Bad in transfected cells. This feature of 19K may provide adenovirus with a selective advantage in evading premature induction of apoptosis by the host cell.

Apoptosis in human papillomavirus16 E7-, but not E6-immortalized human uroepithelial cells

We compared the ability of E6-, versus E7-, immortalized human uroepithelial cells (HUC) to undergo apoptosis in response to gamma radiation. Two independent HPV16 E6-immortalized cell lines, alphaE6#1 and alphaE6#2, that showed low or undetectable p53 levels, failed to undergo apoptosis in response to 18 Gray (Gy) gamma radiation as determined by DNA fragmentation. In contrast, two independent HPV16 E7-immortalized cell lines, alphaE7#1 and alphaE7#2, both of which showed stabilized wildtype p53, underwent apoptosis in the same experiment. Interestingly, both alphaE7#1 and alphaE7#2 showed constitutively elevated BAX and lowered BCL-2 levels, compared to either alphaE6#1 or alphaE6#2. However, elevated BAX and reduced BCL-2 per se were insufficient to trigger apoptosis, as apoptosis occurred only after exposure to gamma radiation. These results support a model in which HPV16 E7-immortalized cells are primed to undergo apoptosis, given an appropriate trigger. This apoptotic response was not observed in alphaE6/E7#1 cells which, like alphaE6-HUCs, showed low p53 levels, nor in late passage alphaE7#1 with spontaneously mutated TP53. These results suggest that E7 immortalization primes HUC for apoptosis in response to gamma radiation, and that this enhanced apoptotic response is p53 dependent.

Dysregulation of cellular proliferation and apoptosis mediates human autosomal dominant polycystic kidney disease (ADPKD)

The proto-oncogene c-myc has been implicated in both cellular proliferation and apoptosis, and we have shown that overexpression of c-myc can induce polycystic kidney disease in transgenic mice. To elucidate the molecular and cellular defects underlying cystogenesis, we have investigated the potential roles of cell proliferation and apoptosis as they relate to c-myc and modulators of c-myc function in human autosomal dominant polycystic kidney disease (ADPKD). Renal c-myc expression was consistently elevated, up to 15-fold, in ADPKD. High levels of c-myc expression correlated with 10- to 100-fold increased proliferation index in cystic epithelium. Interestingly, steady-state levels of bcl-2 mRNA were also increased up to 20-fold and Bcl-2 protein was markedly elevated. In contrast, the expression of bax and p53 was virtually unchanged. However, apoptosis was consistently and significantly increased in ADPKD kidneys, unchecked by high levels of Bcl-2. Together with proliferation, apoptosis may thus represent a general mechanism for cyst growth and tissue remodeling. We conclude that both epithelial cell proliferation and apoptosis required for normal kidney homeostasis are deregulated in ADPKD, recapitulating the renal developmental program. Furthermore, abnormal expression of proto-oncogenes regulating these processes is an important mediator of cystogenesis in human ADPKD.

Oxygen-induced apoptosis in PC12 cells with special reference to the role of Bcl-2

We previously reported that PC12h cells are killed by a high oxygen atmosphere. In this study, we further characterized this oxygen-induced cell death and found apoptotic features, as follows. Firstly, chromatin condensation was observed in cells cultured in a 50% O2 atmosphere. Secondly, cycloheximide and cordycepin, protein and RNA synthesis inhibitors, respectively, prevented the oxygen-induced cell death in PC12h cells, suggesting that it is mediated by an intracellular death program. Thirdly, NGF, CPT-cAMP and depolarization by high potassium medium also effectively inhibited this apoptotic cell death in PC12h cells. The effect of high K+ is thought to be mediated by the influx of Ca2+ into cells through voltage-dependent Ca2+ channels, because nifedipine, an L-type Ca2+ channel blocker, inhibited the effect of high K+. In addition, since the oxygen-induced apoptosis was blocked by the antioxidant vitamin E, this oxygen toxicity is suggested to be mediated by reactive oxygen species. To further characterize this oxygen-induced apoptosis at the molecular level, we used PC12 cells overexpressing the proto-oncogene bcl-2. Although a large number of PC12 cells transfected with the control vector died in a 50% O2 atmosphere within 6 days, bcl-2-transfected PC12 cells survived and proliferated. These findings suggested that our system using PC12 cells will be a useful model with which to analyze the molecular mechanisms of apoptosis induced by oxidative stress in neuronal cells.

Bcl-2 expression in neural cells blocks activation of ICE/CED-3 family proteases during apoptosis

The ICE/CED-3 family of proteases has been implicated in playing a fundamental role in programmed cell death. Bcl-2 protein represses a number of apoptotic death programs, but the biochemical mechanism of its action is not known. We investigated the activation of ICE/CED-3 proteases induced by three apoptotic stimuli (staurosporine, ceramide, and serum withdrawal) in the neuronal cell line GT1-7 and in cells overexpressing Bcl-2. Rapid activation of a 17 kDa subunit of an activated member of the ICE/CED-3 family is demonstrated by affinity-labeling GT1-7 extracts from apoptotic controls cells with a biotinylated ICE/CED-3 inhibitor. This activation corresponds to an increased ICE/CED-3-like protease activity in extracts measured by a fluorogenic substrate assay. In a cell-free system, these extracts induce apoptotic morphological changes in intact nuclei. All three activities are readily inhibited by treatment of control extracts with ICE/CED-3-like protease inhibitors. Overexpressed Bcl-2 inhibits the activation of the 17 kDa protein, the ICE/CED-3-like protease activity in the fluorogenic assay, and the induction of apoptotic morphological changes in HeLa nuclei in the cell-free system, similar to results obtained with ICE/CED-3 protease inhibitors. At the mRNA level, overexpression of Bcl-2 did not alter expression of five members of the ICE/CED-3 family: CPP32, ICE, Mch 2, Nedd 2, and TX. Overexpression of Bcl-2 prevented the apoptosis-induced processing of pro-Nedd 2 to the cleaved form. These data suggest that Bcl-2 participates upstream from the function of ICE/CED-3 proteases and may inhibit apoptosis by preventing the post-translational activation of ICE/CED-3 proteases.

Calcium-dependent, interleukin 1-converting enzyme inhibitor-insensitive degradation of lamin B1 and DNA fragmentation in isolated thymocyte nuclei

Recent work suggests that the proteolytic degradation of the nuclear lamins is a common event in apoptosis, although the nature of the proteases involved is still not clear. Our previous work showed that the degradation of lamin B1 in glucocorticoid-treated thymocytes occurs via a Ca2+-sensitive mechanism and that exogenous Ca2+ promotes lamin degradation in isolated thymocyte nuclei from untreated cells. Here we demonstrate that peptide-based inhibitors of the interleukin 1beta-converting enzyme family of cysteine proteases (Tyr-Val-Ala-Asp fluoromethyl ketone) and of the nuclear scaffold multicatalytic proteinase (Ala-Pro-Phe chloromethyl ketone) block the degradation of lamin B1 to a 21-kDa fragment in thymocytes treated with glucocorticoid, the Ca2+-mobilizing agent thapsigargin, or antibodies to the T cell receptor. However, among a panel of inhibitors specific for several different proteases implicated in apoptosis, only tosylphenylalanyl chloromethyl ketone and the nuclear scaffold protease inhibitor block lamin degradation, histone H1 cleavage, and DNA fragmentation in isolated thymocyte nuclei incubated with Ca2+. Overexpression of human BCL-2 in nuclei by stable transfection resulted in an inhibition of Ca2+-stimulated lamin degradation and DNA fragmentation, suggesting that endogenous nuclear BCL-2 regulates activation of the nuclear scaffold protease. The results demonstrate the existence of an alternative pathway of lamin degradation and DNA fragmentation mediated by a resident Ca2+-stimulated nuclear protease that is not directly dependent upon activation of the interleukin 1beta-converting enzyme family of cell death regulators.

bcl-2 protein is increased in the brain from parkinsonian patients

The proto-oncogene bcl-2 is involved in the regulation of cell death and may be able to block apoptosis in neurons through reduced generation of reactive oxygen species (ROS). The bcl-2 product was measured for the first time in brain (caudate nucleus, putamen and cerebral cortex), ventricular cerebrospinal fluid (VCSF), and lumber CSF (LCSF) from control and parkinsonian patients by highly sensitive two-site sandwich enzyme-linked immunosorbent assay (ELISA). The concentrations of bcl-2 in the nigrostriatal dopaminergic regions were significantly higher in parkinsonian patients than those in controls, whereas this product in cerebral cortex showed no significant difference between parkinsonian and control subjects. Neither VCSF nor LCSF from control or parkinsonian subjects contained the bcl-2 product in the detectable amount (< 5 U/ml). Since oxidative stress may be involved in neurogenerative disorders, accumulation of bcl-2 may reflect a mechanism for counterbalancing ROS-mediated damage, or it might represent the impairment of bcl-2-dependent protection from ROS in parkinsonian brain.

Islet morphogenesis and stem cell markers in rat pancreas

During embryonic development, and possibly also later in life, pancreatic islets of Langerhans originate from differentiating epithelial stem cells. These stem cells are situated in the pancreatic ducts but are otherwise poorly characterized. We found by immunohistochemical staining that protodifferentiated pancreatic epithelial cells from rat embryos of Day 13-Day 15 express the cytoskeletal protein keratin 20, similar to mature duct epithelium. During the period of islet morphogenesis, which occurs between Day 17 and birth, large aggregates of K20-positive duct cells were formed, which gradually differentiated into endocrine cells. This islet morphogenic mechanism has not been described thus far and we did not observe it in postnatal rats. During fetal islet formation, transient expression of vimentin was noted in the duct cells but not in endocrine cells. This intermediate filament protein is not observed in duct epithelial cells after birth. The proto-oncogene product bcl-2, a putative epithelial stem cell marker, was detected in duct cells from fetal and postnatal pancreas. We conclude that K20, vimentin, and bcl-2 are markets for the pancreatic (islet) stem cells.

Reciprocal expression of Bcl-2 and p53 in breast ductal carcinoma

Apoptosis or programmed cell death represents a mechanism by which tumor cells with DNA damage can be deleted. Bcl-2 and p53 gene products have both been linked to apoptosis. Bcl-2 plays a role as an inhibitor of apoptosis that may extend the viability of cells containing genetic alterations and facilitate tumor progression. Mutant p53 has a similar effect. The purpose of this study was to investigate the relationship between bcl-2 and p53 expression and to clarify their roles in apoptosis in different histological graded breast carcinomas. We analysed 101 invasive ductal carcinomas of the breast for the expression of bcl-2, p53, c-erbB-2, estrogen and progesterone receptors using immunohistochemistry. Reciprocal expression of bcl-2 and p53 was present in 71.3% of cases. The bcl-2+/p53-expression pattern was prevalent in histological grade I and II tumors (77.4% and 59.3% respectively) and rarely present in histological grade III (6.3%). Conversely, bcl-2-/p53+ expression pattern was rarely present in histological grade I and II tumors (3.2% and 11.1% respectively) and prevalent in histological grade III (50.0%). Our results also showed that Bcl-2 expression was positively correlated with ER and PR, more prevalent in pre-menopausal status, and negatively correlated with cerbB-2 expression. Bcl-2 expression was involved in tumor progression in well-differentiated tumors and mutant p53 could substitute for bcl-2 function in poorly differentiated tumors. The bcl-2/p53 expression pattern of tumors may be of value in predicting therapeutic response and prognosis. Bcl-2 expression was correlated with other well-established prognostic factors and bcl-2 could be an estrogen-related protein.

Apoptosis and cytologic differentiation in hepatocellular carcinoma on fine needle aspiration samples

OBJECTIVE

To evaluate possible alterations of the mechanisms leading to apoptosis in hepatocellular carcinoma by studying bcl-2 expression on fine needle aspiration biopsy (FNAB) samples using immunocytochemistry.

STUDY DESIGN

The study was performed on a series of 84 hepatocarcinomas aspirated under ultrasound guidance. A Papanicolaou-stained smear for each case was destained and restained for bcl-2 by using the immunoperoxidase technique. bcl-2 Expression was then correlated with cytologic grading and the size of the tumor.

RESULTS

In 16 cases (19%), bcl-2 immunostaining gave a specific cytoplasmic signal. Fourteen of these positive cases were well differentiated, and two were pleomorphic tumors. Six positive cases were smaller than 5 cm, 3 were larger than 5 cm, and 7 were diffuse.

CONCLUSION

A significant percentage of hepatocellular carcinomas produce and accumulate bcl-2 protein in cell cytoplasm. bcl-2 Expression can be detected on destained cytologic smears. bcl-2 Expression seems to correlate with the cytologic degree of differentiation but not with the size of the tumor.

Expression of bcl-2 and apoptotic DNA fragmentation in human endometrial adenocarcinoma cells

Immunohistochemical detection of bcl-2 products and in situ estimation of DNA fragmentation during apoptosis by the nick and labelling method were performed to establish any correlation between these two apparently opposing processes in human solid tumors. Serial sections, one micrometer in thickness, from formalin-fixed and paraffin-embedded tissues of 10 cases of human endometrial adenocarcinoma were examined using the two techniques. A significant fraction of carcinoma cells were found to be stained by both methods, although there existed a general tendency for bcl-2 expression to be negatively correlated with DNA fragmentation in carcinoma tissue. The results thus suggest that bcl-2 expression does not always block apoptosis, and that simultaneous application of bcl-2 immunostaining and DNA nick end labeling is useful for showing the complex nature of apoptosis in histologic slides, especially in gynecological cancers.

Multiparameter flow-cytometric analysis of bcl-2 and Fas expression in normal and neoplastic hematopoiesis

Apoptosis (programmed cell death) is an important regulatory mechanism in hematopoiesis, and is thought to be a principal mechanism of action of cytotoxic chemotherapy. Proteins that modulate apoptosis include bcl-2, which inhibits apoptosis, and Fas (CD95, also known as APO-1), which induces apoptosis in susceptible cells bound by Fas ligand (FasL). To characterize precisely the expression of these apoptosis-regulatory proteins in normal and neoplastic hematopoiesis, the authors have performed multiparameter flow cytometric (FCM) analysis in a series of normal and abnormal marrow specimens. Among normal hematopoietic elements, bcl-2 expression was highest in myeloblasts (29 [+/- 9] x 10(3) molecules of equivalent soluble fluorochrome [MESF]), and lymphocytes (28[+/- 7] x 10(3) MESF). bcl-2 was essentially undetectable in granulocytes and nucleated red blood cells, whereas monocytes and B-cell precursors expressed intermediate levels of bcl-2 (11[+/- 4] x 10(3) and 7[+/- 1] x 10(3) MESF, respectively). Fas expression increased with granulocytic and monocytic differentiation; myeloblasts expressed 8(+/- 2) x 10(3) MESF, whereas granulocytes (15 [+/- 2] x 10(3) MESF) and monocytes (28[+/- 5] x 10(3) MESF) displayed relatively greater intensity of staining for Fas. Among lymphoid cells, Fas expression was heterogeneous. B cells expressed lower intensity Fas staining than both CD4+ and CD8+ T cells. Myeloblasts in 30 cases of myeloid leukemia and myelodysplasia studied for bcl-2 and/or Fas expression manifested variable levels of these molecules (range 9-105 x 10(3) MESF for bcl-2 and 3-33 x 10(3) MESF for Fas). In addition, intraclonal heterogeneity of bcl-2 and Fas expression was seen in certain cases of AML, which correlated with extent of differentiation. Among 28 cases of B-precursor ALL studied for bcl-2 and/or Fas expression, bcl-2 ranged from 22 to 60 x 10(3) MESF (P < .001 versus normal marrow B-cell precursors), and Fas varied between essentially undetectable levels and 6 x 10(3) MESF. In summary, normal marrow subsets display characteristic levels of the apoptosis-regulatory molecules, bcl-2 and Fas. In hematopoietic neoplasms, expression of bcl-2 and Fas varies among cases, and in some instances, within leukemic blast populations. Further study is required to understand the potential significance of this heterogeneous expression of bcl-2 and Fas in hematologic neoplasia.

Incidence of 5' bcl-2 rearrangement in patients with B cell chronic lymphocytic leukemia from India

The incidence of B cell chronic lymphocytic leukemia (B-CLL) is lower in Asian countries, including India, when compared with Western countries. The bcl-2 gene rearrangement was restricted to the 5' region and seen in only one of the 20 Indian patients analyzed. The incidence remains similar to that reported from Western and Japanese institutions.

Bcl-2 mutants with restricted subcellular location reveal spatially distinct pathways for apoptosis in different cell types

Human Bcl-2 is located in multiple intracellular membranes when expressed in MDCK and Rat-1/myc cells. We restricted expression to the endoplasmic reticulum or mitochondria by exchanging the Bcl-2 carboxy-terminal insertion sequence for an equivalent sequence from cytochrome b5 or ActA, respectively. MDCK cells are protected from serum deprivation-induced apoptosis by both wild-type Bcl-2 and the mutant targeted to mitochondria but not by the mutant targeted to endoplasmic reticulum. In contrast, when expressed in Rat-1/myc cells, the Bcl-2 mutant located at the endoplasmic reticulum is more effective than that targeted to mitochondria. In MDCK cells both mutants bind Bax as effectively as wild-type, demonstrating that Bax binding is not sufficient to prevent apoptosis.

Thyroid-stimulating hormone inhibits Fas antigen-mediated apoptosis of human thyrocytes in vitro

The mechanisms of TSH-induced growth stimulation of thyrocytes in vivo have yet to be elucidated. We examined the antiapoptotic effect of TSH toward Fas antigen-mediated apoptosis of thyrocytes. Fas antigen was expressed on approximately 40% of unstimulated thyrocytes, and the expression was significantly inhibited by the addition of TSH in a dose-dependent manner. Treatment of thyrocytes with 8-bromo-cAMP mimicked the effect of TSH, suggesting that the inhibitory effect of TSH on Fas antigen expression was mediated by activating protein kinase A. In contrast, treatment of thyrocytes with either interleukin-1 beta (IL-1 beta) or interferon- gamma (IFN gamma) markedly increased Fas antigen expression on thyrocytes, and these effects were inhibited in the presence of TSH. The expression of the protooncogene product Bcl-2 did not change after the addition of TSH, 8-bromo-cAMP, IL-1 beta, IFN gamma, or a combination of TSH and IL-1 beta or IFN gamma. When thyrocytes stimulated with either IL-1 beta or IFN gamma were treated with anti-Fas IgM mAb, the cells were committed to apoptosis, whereas this apoptotic process was significantly inhibited by the addition of TSH. These results indicate that the Fas antigen is functionally expressed on the surface of thyrocytes, and TSH inhibits Fas antigen-mediated apoptosis of thyrocytes through the inhibitory effect of Fas antigen expression, resulting in the promotion of growth of the thyroid gland.

Cell density increases Bcl-2 and Bcl-x expression in addition to survival of cultured cerebellar granule neurons

The proto-oncogene bcl-2 and its family members, bcl-x and bax are recognized as major regulators of cell death and survival. Although Bcl-2 and Bcl-x are expressed in brain, little is known how they are regulated in neurons. Here we have studied the expression of bcl-2, bcl-xL and bax mRNA in rat cerebellar granule neurons cultured under conditions which influence neuron survival. Insulin-like growth factor-1 and brain-derived neurotrophic factor supported the survival of these neurons, but affected neither the expression of bcl-2, bcl-xL nor bax mRNA. In contrast, bcl-2 and bcl-xL mRNAs were up-regulated in cerebellar granule neurons plated at high density exhibiting an increased neuronal survival. Western blots showed that cell density also increased Bcl-2 protein level. However, conditioned medium from dense cultures did not affect the level of bcl-2 mRNA nor survival of the neurons. This suggests that cell density promotes survival and regulates Bcl-2 expression in cerebellar granule neurons through a signaling pathway different from known neurotrophic factors.

Excessive apoptosis of mature T lymphocytes is a characteristic feature of human immune senescence

Recent evidence suggests that apoptotic deletion of activated mature lymphocytes is an essential physiological process implicated in both the regulation of the immune response and the control of the overall number of immunocompetent cells. Tightly interrelated signaling mechanisms convey either activation or death messages, achieving the necessary equilibrium between cell proliferation and cell deletion. During the course of aging, numerous alterations of these signaling pathways may shift the balance toward cell death. In the present investigation, the reduced DNA synthesis of anti-CD3 activated T lymphocytes isolated from elderly individuals is associated with an important and early cell deletion from the cultures. Visualization of DNA fragmentation in the remaining activated cells argues in favour of the apoptotic nature of the cell deletion. Quantification of histone-associated DNA fragments shows that the apoptotic process is greatly amplified in activated lymphocytes derived from senescent organisms. Further analysis reveals that IL-2 deprivation does not play a significant role in the age-related increase in apoptosis. Partial correction of this excessive apoptosis by products that bypass the early steps of the signaling cascade suggests that transmembrane signaling defects are involved in this process. Exploration of the antioxidant pathway reveals that the increased susceptibility of lymphocytes from senescent organisms to apoptosis is not explained by a decreased Bcl-2 expression and is not influenced by a modification of the intracellular concentration of glutathione (GSH).

Inactivation of bcl-2 results in progressive degeneration of motoneurons, sympathetic and sensory neurons during early postnatal development

Bcl-2 is a major regulator of programmed cell death, a critical process in shaping the developing nervous system. To assess whether Bcl-2 is involved in regulating neuronal survival and in mediating the neuroprotective action of neurotrophic factors, we generated Bcl-2-deficient mice. At birth, the number of facial motoneurons, sensory, and sympathetic neurons was not significantly changed, and axotomy-induced degeneration of facial motoneurons could still be prevented by brain-derived neurotrophic factor (BDNF) or ciliary neurotrophic factor (CNTF). Interestingly, substantial degeneration of motoneurons, sensory, and sympathetic neurons occurred after the physiological cell death period. Accordingly, Bcl-2 is not a permissive factor for the action of neurotrophic factors, and although it does not influence prenatal neuronal survival, it is crucial for the maintenance of specific populations of neurons during the early postnatal period.

Bcl-2 expression as a predictor of chemosensitivities and survival in small cell lung cancer

PURPOSE

The bcl-2 gene belongs to a new category of oncogene that inhibits programmed cell death (apoptosis). No data are available on the frequency or clinical importance of its expression in patients with small cell lung cancer (SCLC), although its expression is reported in SCLC cell lines. We investigated the correlation between bcl-2 expression and prognosis, including response to chemotherapy, in SCLC patients and report our findings here.

MATERIALS AND METHODS

Tumor specimens biopsied bronchoscopically in 38 SCLC patients were used for immunohistochemical study. Bcl-2 oncoprotein was detected by obtaining an immunostain using a specific monoclonal antibody, DAKO-bcl-2, 124. All patients received more than two courses of chemotherapy with 3- to 4-week intervals.

RESULTS

We detected bcl-2 expression in 21 of the 38 SCLC patients (55%). In 17 patients with bcl-2-negative tumors, the objective response to chemotherapy was 76% with 12% complete response and in 21 patients with bcl-2-positive tumors it was 62% with 8% complete response. The difference in response rate was not significant. In patients with bcl-2-positive tumors, survival time tended to be shorter than in those with bcl-2-negative tumors. There was no significant correlation between bcl-2 expression and clinical factors (gender, age, smoking, performance score, staging).

CONCLUSIONS

In 21 of the 38 SCLC patients bcl-2 oncoprotein was abnormally expressed and its expression may be associated with shorter survival times and poor response to chemotherapy.

Estradiol regulates tumor growth by influencing p53 and bcl-2 expression in human endometrial adenocarcinomas grown in nude mice

This study analyzes the effects of estradiol on p53 and bcl-2 expression, tumor growth and cell kinetic parameters in three human endometrial adenocarcinomas grown in nude mice. The tumors used were estradiol receptor (ER) positive but differed in receptor concentration and hormone sensitivity. All three tumors expressed wild-type p53 protein. Using a tumor with an estradiol independent but responsive (inhibited) growth phenotype, we found that an increase in the circulating estradiol concentration led to increases in p53 expression and a decrease in bcl-2 levels, resulting in increased cell loss (CL) measured as delayed tumor growth. In another tumor which demonstrated estradiol independent and resistant growth, we observed an estradiol dose-related increase in p53 expression but no changes in bcl-2 expression or cell kinetic parameters. The ER mechanism of these cells was at least partly intact, as evidenced by maintained PgR induction. The third tumor showed an estradiol independent and resistant growth phenotype and a non-functional ER mechanism, lacking PgR induction. After estradiol treatment of the tumor-bearing animals no changes were observed in p53 or bcl-2 expression or in cell kinetics. We conclude that estradiol may regulate tumor growth in some ER positive human endometrial adenocarcinomas through regulation of p53 expression, which in turn regulates the bcl-2 protein concentration. Furthermore, this regulation of p53 expression is estradiol dose dependent. These growth regulating functions appear to be strongly influenced by ER mechanisms and do not seem to operate synchronously in tumors with an estradiol resistant growth phenotype.

SSCP pattern indicative for p53 mutation is related to advanced stage and high-grade of tongue cancer

53 and bcl-2 are involved in the control of cell cycling and apoptosis. Environmental factors such as smoking and radiation can disturb p53 function and predispose a cell to malignant transformation. To investigate the role of p53 mutations, as well as p53 and bcl-2 protein expression in squamous cell carcinoma of the tongue, 39 samples were analysed. Since neck metastasis is the most important prognostic factor of this disease, samples from patients both with and without nodal disease were selected to find out whether there was any difference between the groups. Non-radioactive single-stranded conformation polymorphism (SSCP) was used to screen p53 mutations; an altered SSCP pattern indicating p53 mutation was found in 21 samples (54%). A significant correlation between tumour size, histological differentiation and p53 mutations was found (P < 0.01). Immunocytochemically, nuclear expression of p53 was moderate or strong in 18 (46%) samples. No correlation between altered p53 SSCP pattern and p53 immunoreactivity was seen. bcl-2 expression was cytoplasmic; moderate or strong staining was detected in only six of the carcinoma samples (15.5%). Interestingly, there was a significant correlation between smoking and bcl-2 expression (P < 0.01): all six samples with moderate or strong staining were taken from heavy smokers. Furthermore, all those patients died within 32 months.

Expression of bcl-2 in rheumatoid arthritis

Since defective apoptosis has been suggested to play a role in the development of autoimmune diseases, we have investigated the expression of the proto-oncogene bcl-2 in patients with rheumatoid arthritis (RA). The expression of bcl-2 was studied in peripheral blood (PB) and synovial fluid (SF) lymphocytes and synovial tissues (ST) from patients with RA using immunohistochemistry, flow cytometry and nucleic acid hybridization. Patients with reactive arthritis (ReA) or osteoarthritis (OA) and healthy individuals were used as controls. The expression of bcl-2 protein in PB lymphocytes and the expression of bcl-2 mRNA in PB mononuclear cells (PBMC) was similar in healthy controls and patients with RA. However, bcl-2 protein expression was significantly reduced in SF lymphocytes when compared to PB lymphocytes. Similar results were observed with lymphocytes from patients with ReA, and irrespective of whether total lymphocytes, T cells or different T-cell subsets were studied. In the synovial sections, the expression of bcl-2 was restricted to lymphocytes, and bcl-2+ cells were observed in the majority of samples from patients with RA, OA and ReA. These data indicate that the expression of bcl-2 is not increased in the lymphocytes or ST derived from patients with RA. Instead, decreased expression of bcl-2 protein in SF lymphocytes compared to PB lymphocytes was demonstrated. We suggest that bcl-2 does not play a significant role in the pathogenesis of RA.

Protection of retinal ganglion cells from natural and axotomy-induced cell death in neonatal transgenic mice overexpressing bcl-2

Approximately half of the retinal ganglion cells (RGCs) present in the rodent retina at birth normally die during early development. Overexpression of the photo-oncogene bcl-2 recently has been shown to rescue some neuronal populations from natural cell death and from degeneration induced by axotomy of nerves within the peripheral nervous system. Here we study in vivo the role of the overexpression of bcl-2 in the natural cell death of RGCs and in the degenerative process induced in these cells by transection of the optic nerve. We find that in newborn bcl-2 transgenic mice, the number of RGCs undergoing natural cell death is considerably lower than in wild-type pups. Consistently, a vast majority (90%) of the ganglion cells found in the retina of neonatal transgenics are maintained in adulthood, whereas only 40% survive in wild-type mice. After transection of the optic nerve, the number of degenerating ganglion cells, determined by counting pyknotic nuclei or nuclei with fragmented DNA, is substantially reduced in transgenic mice. In wild-type animals, almost 50% of ganglion cells degenerate in the 24 hr after the lesion, whereas almost the entire ganglion cell population survives axotomy in transgenic mice. Therefore, overexpression of bcl-2 is effective in preventing degeneration of this neuronal population, raising the possibility that ganglion cells are dependent on the endogenous expression of bcl-2 for survival. The remarkable rescue capacity of bcl-2 overexpression in these neurons makes it an interesting model for studying natural cell death and responses to injury in the CNS.

Expression of bcl-2 oncoprotein in various types of glomerulonephritis and renal allografts

BACKGROUND

Bcl-2 oncogene was identified as a transcript associated with the t (14;18) and exhibits the unique functional role of blocking apoptosis. Apoptosis as a remodelling mechanism has been reported to embryonic and adult kidney. The aim of this study was to investigate the expression of bcl-2 protein in normal and diseased renal tissue and to define any correlation with the type of renal injury.

MATERIALS AND METHODS

Our material comprised of 10 normal adult kidneys, 31 renal allografts with acute (22) and chronic (9) rejection, and 70 renal biopsies with various types of primary (49) (31 proliferative and 18 non-proliferative) and secondary (21) glomerulonephritis. The immunohistochemical strept.ABC method was performed on paraffin sections for the detection of bcl-2 protein with a monoclonal antibody after microwave pretreatment.

RESULTS

Bcl-2 protein was detected in all the cases of normal and diseased renal tissue, showing an analogous expression. The antigen was expressed in a few parietal epithelial cells, and in the majority of distal and collecting tubular epithelial cells, but not in the glomerular capillary tuft. No difference was found in bcl-2 expression between cases of proliferative and non-proliferative glomerulonephritis as a whole, or between primary and secondary glomerulonephritis. Bcl-2 expression in acute and chronic rejection demonstrated a similar cytoarchitectural expression to the one observed in normal kidneys and glomerulonephritis. Bcl-2 was detected in podocytes near intraglomerular fibrotic lesions and in epithelial cells of early adhesions and cellular crescents, wherever observed in cases of glomerulonephritis. However, bcl-2 expression in proximal tubular epithelial cells was significantly higher in cases of proliferative glomerulonephritis than in non-proliferative glomerulonephritis (P<0.01), while bcl-2 expression in parietal epithelial cells in cases of chronic rejection was higher than in cases of acute rejection (P<0.08).

CONCLUSIONS

The absence of bcl-2 expression in normal and diseased glomeruli suggests and supports the reported notion that the mechanism of apoptosis may be available in the injured glomerulus. Moreover, bcl-2 expression in podocytes near intraglomerular fibrotic lesions and in epithelial cells of early adhesions and cellular crescents indicates the deregulation of apoptosis and its possible role in the progression of glomerular scarring. Key words: apoptosis; bcl-2 oncoprotein; glomerulonephritis; immunohistochemical; renal rejection.

Flow cytometric analysis of apoptosis and bcl-2 in primary breast carcinomas: clinical and biological implications

Analysis of programmed cell death (apoptosis), of bcl-2, a critical regulator of this process, and of the proliferative fraction may provide detailed information on the biologic characteristics of tumor cell populations. To investigate the potential role of these parameters in assessing mammary carcinoma, we adapted flow cytometric procedures for concurrent measurement of apoptosis, bcl-2 expression, and cell proliferation in 54 primary breast carcinomas and correlated the findings with traditional clinicopathologic information. Overall, a significant inverse relationship between apoptosis levels and bcl-2 expression was observed (P = 0.005). Apoptosis levels correlated significantly with DNA aneuploidy (P = 0.03) and S + G2M fractions (P = 0.005) of these tumors. A significant correlation between bcl-2 expression and estrogen receptor positivity (P = 0.05) and DNA diploidy (P = 0.02) was noted. Bcl-2 expression, however, was inversely correlated with S + G2M fractions (P = 0.001). We conclude that analysis of apoptosis and bcl-2 by flow cytometry allows further characterization of tumor cell populations that may be useful for prognostic and therapeutic management of breast carcinoma.

Effect of dolastatin 10 on human non-Hodgkin's lymphoma cell lines

It is crucial to incorporate new and more potent antineoplastic agents in treating non-Hodgkin's lymphoma since standard chemotherapy fails to cause a significant increase in the survival rate. A potential chemotherapeutic agent is dolastatin 10; hence, the objective of our study is to investigate the effect of the antiproliferative agent dolastatin 10 on different grades of non-Hodgkin's lymphoma cell lines. All cell lines exposed to dolastatin 10 initiated an apoptosis process. Alteration of oncogenes and their product may direct the entry of the cells into apoptosis, among these oncogenes are bcl-2 and c-myc. All cell lines tested expressed c-myc and bcl-2 proteins. However, 24 h after exposing the cell lines to 1 ng/ml dolastatin 10, bcl-2 expression was abolished but there was no significant change in c-myc protein expression. The contradictory roles of c-myc in cell proliferation and death require that other gene(s) products regiment the outcomes of c-myc activity on a cell. A possible candidate for such a modifying gene is bcl-2, whose product prolongs cell survival and blocks apoptosis. Given the above, dolastatin 10 induction of cell arrest is the initiating signal to downregulate the antiapoptotic bcl-2 and reactivate the apoptotic pathway. The reductions in bcl-2 may stabilize the c-myc proliferative action and induce apoptosis.

Selective c-Jun overexpression is associated with ionizing radiation-induced apoptosis in the developing cerebellum of the rat

Immunohistochemistry to Bcl-2, Bax, c-Myc, c-Fos, Fos-related, c-Jun, Jun B and Jun D was used to study the involvement of these factors in ionizing radiation-induced apoptosis in the cerebellum of the developing rat. Selective c-Jun overexpression was observed during the whole process of radiation-induced cell death. Furthermore, c-Jun overexpression was restricted to apoptotic cells, as shown by double labeling with the method of in situ labeling of nuclear DNA fragmentation and c-Jun immunohistochemistry. This is the first in vivo evidence that selective c-Jun overexpression is associated with apoptotic cell death in the developing nervous system following ionizing radiation.

Detection of apoptosis in human endometriotic tissues

To clarify whether apoptosis is involved in endometriosis, we obtained eutopic endometrial tissues along with endometriotic tissues from the uterus (adenomyosis) (n = 12) and from the ovary (n = 12) from patients undergoing gynaecological surgery. Apoptosis-induced DNA fragmentation was detected by the TdT-mediated dUTP-biotin nick-end labelling method, and immunostaining with a monoclonal antibody against the Fas, Le(y) or B-cell leukaemia/lymphoma-2 (bcl-2) was also performed using the same tissue section. Analysis showed that apoptosis was occurring in all the samples of ovarian endometriotic tissue but in only two of the 12 adenomyotic and in five of the 24 eutopic endometrial tissue samples. In none of these cases was apoptosis correlated with phases of the menstrual cycle. The expression of bcl-2 in the eutopic endometrial and adenomyotic tissues was limited to the proliferative phase, and was observed in only one of the 12 cases of ovarian endometriosis. Fas and Ley were expressed randomly across a wide range in both the eutopic and ectopic endometrial tissues. These results suggest that the features of ovarian endometriosis are different from those of adenomyosis and eutopic endometrium in terms of the involvement of apoptosis. In addition, the regulatory mechanism involved in ovarian endometriosis may differ from that in other endometrial cells.

Analysis of interaction sites in homo- and heteromeric complexes containing Bcl-2 family members and the cellular prion protein

The cellular prion protein (PrP) binds to the C-terminus of Bcl-2 but not Bax. Therefore, we examined whether the C-terminus of Bcl-2 was important for other homomeric and heteromeric protein-protein interactions. Using the yeast two hybrid system and co-immunoprecipitation, three sites of homomeric interactions were identified within Bcl-2. The carboxy terminal 37 amino acids selectively homodimerized. Two additional regions of Bcl-2 (residues 1-129 and 126-200) interacted with each other, but not themselves permitting both intra- and intermolecular association. In addition, we analyzed heteromeric interactions of Bcl-2 with PrP and two Bcl-2 related proteins, Bax and A1. The domain requirements for binding of those three proteins to Bcl-2 were different from one another. Bax binding required almost the entire Bcl-2 molecule, while A1 bound to the amino terminal region (residues 1-82). PrP associated with the carboxy terminus of Bcl-2 (amino acids 200-236). These data suggest configurational models for Bcl-2 containing complexes. First, Bcl-2 may exist as both heterodimers and heteromultimers. Second, molecules such as Bax and A1 may serve to cap chains of Bcl-2 homodimers by interacting with dimerization domains in the extramembrane region. PrP may disrupt chains of Bcl-2 molecules at the homomeric association site in the transmembrane region.

Bcl-2 protein expression in lung cancer and close correlation with neuroendocrine differentiation

For determination of the cellular distribution of bcl-2 expression in lung cancer and clarification of its correlation with cell neuroendocrine differentiation, Bcl-2 immunostaining was carried out on a large series of formalin-fixed, paraffin-embedded lung cancer samples, and four general neuroendocrine marker and seven peptide hormone stainings were carried out on all Bcl-2-positive squamous cell carcinomas and adenocarcinomas of the lung as well as on 8 pulmonary neuroendocrine carcinomas histologically diagnosed. In addition, 3 small cell lung cancer cell lines were studied by Western blotting. Neuroendocrine differentiation in Bcl-2-negative squamous cell carcinomas and adenocarcinomas was examined with chromogranin A and alpha-subunit of Go protein stainings. Bcl-2 protein was detected in 104/111 small cell carcinomas, 8/8 neuroendocrine carcinomas, 0/6 typical (well differentiated) carcinoids, 23/64 squamous cell carcinomas, 4/65 adenocarcinomas, and all 3 small cell lung cancer cell lines. All 8 neuroendocrine carcinomas, 11 of the Bcl-2-positive squamous cell carcinomas, and all 4 Bcl-2 positive adenocarcinomas expressed multiple neuroendocrine markers. The distributions of Bcl-2 and neuroendocrine marker immunoreactivity closely paralleled each other on consecutive sections. In squamous cell carcinomas, Bcl-2-positive cells could be roughly subdivided into those with neuroendocrine differentiation features, usually demonstrating intense Bcl-2 staining, with basaloid tumor cells usually expressing weak to moderate Bcl-2 staining. The present study clearly shows Bcl-2 protein expression to be remarkably differentially regulated according to histological types of lung cancers and to appear to quite likely be closely associated with neuroendocrine differentiation of tumor cells, indicating that bcl-2 is importantly involved in cell development and differentiation, in addition to protecting cells from apoptosis. Bcl-2 might be usable as a neuroendocrine marker in lung cancers and possibly also in neural-crest-derived tumors.

MHC class II tolerant T cells undergo apoptosis upon re-exposure to tolerogen in vivo

Tolerance of MHC class II alloantigens can be achieved by intravenous injection of semiallogeneic hematopoietic cells into neonatal mice. Lymphoid cells of tolerant mice fail to proliferate or secrete interleukins IL-2 or IL-4 when stimulated in vitro with tolerogen. Since the lymphoid organs of B10.T(6R) tolerant mice contain normal levels of I-E reactive (V beta 11+) CD4+ T cells, deletion of alloreactive T cells does not appear to be the mechanism involved in the tolerance induction. To test whether T cells from tolerant animals can become activated under conditions that do not involve alloantigen stimulation, we stimulated these cells with immobilized anti-V beta 11 antibodies. Spleen cells from grafted tolerant and rejector mice proliferated in response to anti-V beta 11+ antibodies, suggesting they were not inert. We then tested whether V beta 11+ T cells from grafted mice can be induced to proliferate following stimulation with alloantigen in vivo. We adoptively transferred T cells from grafted tolerant and rejector mice into irradiated (B10.AQR x B10.T(6R))F1 mice and harvested the lymphoid organs after 65 h. Cells from both grafted tolerant and rejector mice underwent blast transformation, but only cells from rejector mice proliferated when exposed to immobilized anti-V beta 11 antibodies. The failure of V beta 11+ cells from tolerant mice to proliferate after in vivo stimulation may be because they are apoptotic. To test this hypothesis, spleen cells from naive or neonatally tolerized (with (B10.AQR x B10.T(6R))F1 cells) B10.T(6R) mice were adoptively transferred into irradiated (B10.AQR x B10.T(6R))F1 mice and bcl-2 expression was analysed in harvested V beta 11+ cells. Large cells recovered from recipients of naive 6R cells expressed bcl-2 mRNA. By contrast, large cells harvested from recipients of tolerized 6R cells did not express bcl-2 mRNA, suggesting bcl-2 mRNA expression was downregulated in these mice. Moreover, in another experiment, large V beta 11+ cells from grafted tolerant animals recovered after transfer into irradiated (B10.AQR x B10.T(6R))F1 mice did not express the bcl-2 protein as determined by flow cytometry, and contained fragmented DNA as assessed by the TUNEL method. Taken together, these data suggest that MHC class II tolerant T cells undergo apoptosis upon re-exposure to tolerogen in vivo.

Expression of CD95 antigen and Bcl-2 protein in non-Hodgkin's lymphomas and Hodgkin's disease

CD95 (APO-1/Fas) is a member of the superfamily that includes the nerve growth factor and tumor necrosis factor receptors, OX40, CD27, CD30, and CD40. Present on a minority of resting blood lymphocytes, CD95 expression is upregulated on activated T and B lymphocytes and natural killer cells, where binding of the antigen by anti-Fas and anti-APO-1 antibodies has been shown to induce apoptosis. This CD95-mediated apoptosis is at least partially inhibited by expression of the Bcl-2 protooncogene. To evaluate possible roles of CD95 and Bcl-2 in growth regulation of lymphoid neoplasms, we studied by immunohistochemistry the expression of CD95 and Bcl-2 in 67 B- and 5 T-cell lymphomas, and 10 cases of Hodgkin's disease. In all, 29 B and 2 T cell lymphomas, and 9 cases of Hodgkin's disease expressed CD95. Compared with diffuse large B-cell and Burkitt-like lymphomas, lowgrade B-cell lymphomas more frequently expressed CD95 (52% versus 26%; P < .005). None of the B-cell small lymphocytic lymphomas or mantle cell lymphomas expressed CD95, whereas the majority of follicle center lymphomas, extranodal marginal zone B-cell lymphomas, and immunocytomas were CD95+. Of the 29 CD95+ B-cell lymphomas, only 33% of the high-grade group coexpressed Bcl-2, compared with 87% of the low-grade group (P < .04). Two of three peripheral T-cell lymphomas--including one anaplastic large cell lymphoma--expressed CD95. Staining for CD95 was seen in 9 of 10 cases of Hodgkin's disease. The infrequent expression of CD95 in high-grade B-cell lymphomas suggests an association between loss of CD95 expression/function and a more aggressive tumor grade. Whereas frequent coexpression of Bcl-2 with CD95 may protect low-grade B-cell lymphomas against CD95-mediated apoptosis, in the high-grade group such coexpression is infrequent, and other regulators besides Bcl-2 may be involved in modulating the apoptosis signal delivered by CD95.

Cell renewal and functional morphology of human lactating breast: presentation of a new mode of cell death ('magentosis') characterized by nuclear periodic acid-Schiff reactivity

Cell kinetics and functional morphology of the human lactating breast were analyzed using 21 paraffin-embedded specimens of the lactating breast obtained by biopsy or surgery and two of the 'resting' breast. Four types (I-IV) of lactating lobules were categorized histologically, and were well correlated with their functional status demonstrated by immunohistochemistry for epithelial membrane antigen, beta-casein, lipase, lactoferrin, secretory component and IgA. Type I corresponded to a pre-lactating state, type II to an actively lactating state, type III to an early stage of regression, and type IV to an advanced stage of regression. Cell proliferation monitored by Ki-67 (MIB-1) immunostaining was at the highest level in type I lobules followed by type IV, while the labeling indices were low in types II and III. Apoptosis demonstrated by terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end-labeling (TUNEL) method showed labeling profiles comparable with the proliferative activity. Holocrine-type desquamative cells with intact-appearing nuclei were frequently recognized in type II lobules. In type III, a peculiar form of cell death, designated 'magentosis', was demonstrated. These degenerative cells occasionally shedding into the acinar lumen possessed homogeneous pale, TUNEL-negative nuclei with diastase-resistant periodic acid-Schiff (PAS) reactivity. 'Magentosis' specifically identified in an early phase of involution of the human lactating breast might represent a unique mode of cell death distinguishable from apoptosis and necrosis.

New members of the Bcl-2 family and their protein partners

Any model of apoptosis must explain the mechanism of action of the Bcl-2 family of proteins. This has proved to be unusually difficult. This review concentrates on some of the newly isolated members of this growing family and attempts to provide an insight into the complexity of interactions through which the Bcl-2 proteins modulate apoptosis.

Dysregulation of bcl-2, c-myc, and Fas expression during tricyclic antidepressant-induced apoptosis in human peripheral lymphocytes

Tricyclic antidepressants (TCAs) have been shown to induce apoptosis in human lymphocytes. In the present report, we investigated in parallel the regulation of the three oncogenes bcl-2, c-myc, and Fas. A reduction in c-myc and bcl-2 levels of 35-40% and 22-27%, respectively, was observed. On the other hand, Fas expression on the outer surface of the plasma membrane was increased up to 31%. In conclusion, bcl-2, c-myc, and Fas are undergoing dysregulation due to TCA-induced apoptosis.

Effects of modulators of protein kinases on taxol-induced apoptosis of human leukemic cells possessing disparate levels of p26BCL-2 protein

Taxol-induced polymerization of tubulin into stable microtubules and cell cycle metaphase arrest have been demonstrated to result in internucleosomal DNA fragmentation and morphological features of apoptosis in human leukemia cells. Recent studies have also shown that Taxol-induced apoptosis, but not Taxol-induced microtubular bundling or mitotic arrest, is significantly inhibited in cells that overexpress the bcl-2 gene product p26BCL-2. In the present studies we examined the effects of several modulators of activities of protein kinases on Taxol-induced DNA fragmentation and apoptosis in human pre-B leukemia 697 cells transfected with the cDNA of the bcl-2 gene and expressing high intracellular levels of p26BCL-2 (697/BCL-2 cells). Treatment with 0.1-1.0 microM MTaxol for 24 h produced prolonged mitotic arrest of control 697/neo cells, which had been transfected with the neomycin resistance gene. This resulted in apoptosis-associated large DNA fragments ranging between 5 and 200 kb and internucleosomal DNA fragmentation. Cotreatment with the phorbol ester phorbol dibutyrate (PdBU) significantly reduced Taxol-induced internucleosomal and large DNA fragmentation and inhibited apoptosis of 697/neo cells. In contrast, a combined exposure to Taxol and staurosporine (ST; 5 or 50 ng/ml), a potent inhibitor of protein kinase C and other kinases, significantly increased DNA fragmentation and apoptosis of 697/neo cells. Additionally, in 697/BCL-2 cells, ST partially overcame the suppressive effects of high p26BCL-2 levels on Taxol-induced apoptosis. Cotreatment with the tyrosine kinase inhibitor Genistein (30 microM) markedly inhibited Taxol-induced DNA fragmentation and apoptosis of 697/neo cells. However, it is noteworthy that the modulations of Taxol-induced DNA fragmentation and apoptosis by PdBU, ST, and Genistein occurred without significant effects on Taxol-mediated mitotic arrest of 697/neo cells. These agents also did not affect intracellular p26BCL-2 levels in 697/neo or 697/BCL-2 cells. These findings indicate that Taxol-induced apoptosis can be modulated by agents that affect the activities of protein kinases, and these effects are not mediated by modulations of Taxol-induced mitotic arrest or by alterations of intracellular p26BCL-2 levels.

Expression of topoisomerase II, bcl-2, and p53 in three human brain tumor cell lines and their possible relationship to intrinsic resistance to etoposide

We characterized three human brain tumor cell lines (D54, HBT-20, and HBT-28) with respect to resistance to etoposide (VP-16), a topoisomerase II-reactive drug. All three cell lines were inherently resistant to VP-16 when compared to other human cell lines, with D54 showing the greatest resistance using colony formation assays. Resistance to VP-16 has been attributed to decreased drug uptake and changes in topoisomerase II; however, drug uptake and topoisomerase II protein levels (immunoblot) were no lower in D54 than in HBT-20 and HBT-28, cell lines relatively more sensitive to VP-16. More to the point, measurement of topoisomerase II-mediated DNA cleavage of cellular DNA after treatment with VP-16 showed that the topoisomerase II in these cells was active. These data indicate mechanisms other than those attributable to decreased drug uptake or altered topoisomerase II exist for clinical resistance to VP-16. VP-16-induced DNA cleavage has been associated with apoptosis in some cell lines; however, neither DNA laddering nor morphological changes characteristic of apoptosis were detected in these cell lines after treatment with VP-16. Bcl-2 and mutant p53 were present in these cells. Either of these conditions can prevent apoptosis and could explain a dissociation between the proximal mediator of VP-16-induced cytotoxicity (topoisomerase II-DNA complex formation) and cellular death.

Predictive and prognostic markers in a series of patients with head and neck squamous cell invasive carcinoma treated with concurrent chemoradiation therapy

It has been proposed that diverse anticancer drugs and radiation therapy may induce a mode of cell death with the characteristics of apoptosis. Since apoptosis is under the control of several oncogenes, we analyzed the expression of the protein encoded by the proto-oncogenes bcl-2 and p53. Furthermore, we studied cell proliferation [using PC-10 mAb to proliferating cell nuclear antigen (PCNA)] and vascularization [using the CD-31 mAb and by counting intratumoral microvessel density (IMD)] using immunocytochemistry. A series of 73 patients with clinical stage II-IV squamous cell invasive carcinoma of the head and neck (H&N) were treated with concurrent chemoradiation therapy (cisplatin, 80 mg/m2, versus carboplatin, 375 mg/m2, three times every 3 weeks and a total dose of radiation therapy of 64 Gy in 6-8 weeks). We correlated the expression of these markers, determined prior to treatment, with response to the therapy and prognosis. Bcl-2 protein was expressed in 37.4% of the carcinomas (25/67 evaluable), and it was not significantly associated with any other feature studied. Forty (56. 4%) of the 71 carcinomas evaluable for p53 were p53 positive; the median IMD was 38 microvessels/field at the hot spot (range, 18-80), and the median percentage of nuclei labeled by the PC-10 mAb was 50% (range, 0-95%). In the univariate analysis, regional lymph node negativity (P = 0.016), good performance status (PS) (PS >/= 90; P = 0.044), bcl-2 positivity (P = 0.070), and low vascularization (P = 0. 085) were significantly associated with a higher probability of complete remission. In the multivariate analysis (final model), only IMD (continuous variable; P = 0.045) and PS (P = 0.017) retained significance. As far as prognosis is concerned, in the univariate analysis, patients with tumors with low histological grading (grades 1-2; P = 0.006), p53 negative (P = 0.09), bcl-2 positive (P = 0.08), and high PCNA labeling (P = 0.06) had a significantly better disease-free survival. In the multivariate analysis, only grading (P = 0.003) and p53 (P = 0.04) retained significance for disease-free survival. For overall survival, in the univariate analysis, the following markers were significantly prognostic when only deaths due to progression are considered: response to therapy (P = 0.00001), PS (P = 0.04), nodal status (P = 0.028), PCNA (P = 0.04), p53 (P = 0. 08), and grading (P = 0.01). In the multivariate analysis, only patients who achieved complete response (P = 0.00002), high PCNA values (P = 0.002), and low histological grading (P = 0.01) retained a statistically significant probability of better overall survival. Our results suggest that in this series of H&N cancer patients the markers capable of predicting response to therapy are distinct from those associated with prognosis, once the remission has been achieved. This information is potentially useful to the clinician for developing a more rational therapeutic approach for H&N cancer patients eligible for concurrent chemoradiation therapy.

Prognostic value of bcl-2 oncoprotein expression in stage II colon carcinoma

The bcl-2 proto-oncogene encodes a Mr 25,000 protein that has been shown to prevent apoptosis or programmed cell death. The bcl-2 protein is detectable in basal cells of normal colonic epithelium, and an altered topographic distribution of this protein is found in colonic neoplasms. However, the clinical significance of abnormal bcl-2 expression in colon carcinomas remains unknown. We examined the prognostic value of the bcl-2 protein in TNM stage II colon carcinomas and its relationship to DNA ploidy, cell proliferation indices, p53 expression, and clinicopathological features. We analyzed 119 resected and otherwise untreated, paraffin-embedded stage II colon carcinomas for bcl-2 and p53 protein expression using immunohistochemistry. DNA ploidy and proliferative index (% S-phase + % G2-M) were determined by flow cytometry, and tumor grade and vascular microinvasion were assessed on histological sections. Cytoplasmic expression of the bcl-2 protein was detected in 72 (66%) of 110 carcinomas, and a high level of expression was significantly correlated with diploid DNA content (P = 0.02) and low proliferative activity (P = 0.005). bcl-2 was not associated with nuclear p53 expression. In a univariate analysis, a higher fraction of bcl-2-positive tumor cells was associated with better relapse-free survival (P = 0.02) and overall survival (P = 0.05) rates. Moreover, a high level of bcl-2 expression was an independent predictor of better relapse-free survival (P = 0.04), but not overall survival (P = 0.14), after adjustment for other variables, including proliferative index, DNA ploidy, and race. In conclusion, bcl-2 overexpression is associated with favorable prognostic features and may predict clinical outcome in stage II colon carcinomas.

Hyaluronidase induces murine L929 fibrosarcoma cells resistant to tumor necrosis factor and Fas cytotoxicity in the presence of actinomycin D

Actinomycin D (ActD) enhances the potency of tumor necrosis factor-alpha (TNF-alpha) in killing cancer cells. However, it is determined in this study that murine L929 fibrosarcoma cells, when pretreated with bovine testicular hyaluronidase for 12-24 h, became resistant to the cytotoxic effect of TNF-alpha in the presence of DNA intercalators, such as ActD, doxorubicin, and daunorubicin. Monoclonal anti-Fas antibody-mediated apoptosis in the presence of ActD was also blocked in hyaluronidase-pretreated L929 cells. Hyaluronidase failed to up- or downregulate the expression of apoptosis regulatory proteins, including Bcl-2, Bcl-xL, ICH-1, and TIAR, suggesting that these proteins were not involved in the hyaluronidase-induced resistance to TNF/ActD. A semisynthetic polysulfated hyaluronic acid (HA) inhibited the increased TNF/ActD resistance, whereas unmodified HA, dextran sulfate, and naturally polysulfated glycosaminoglycans had no effect. Evidence is provided here that the induced resistance is related to serum fetuin and a novel intracellular 35-kDa TNF-binding protein (intra TBP). Under serum-free conditions, L929 became refractory to TNF/ActD cytotoxicity and hyaluronidase reversed the resistance. Exogenous fetuin increased L929 cell spreading and proliferation, and restored hyaluronidase-induction of TNF/ActD resistance in these serum-starved cells. Hyaluronidase failed to reduce the expression of TNF-receptors and their binding of TNF-alpha. However, binding and Western-blotting analyses revealed that hyaluronidase downregulated the intra-TBP. Overall, these observations suggest that serum fetuin and intraTBP are involved in the hyaluronidase induction of TNF/ ActD resistance.

Expression of Bcl-2 protein in human laryngeal keratoses

Strong Bcl-2 immunostaining was detected in 2 of 21 samples of human laryngeal keratoses, one of which contained neither p53 gene mutation nor human papillomavirus sequences nor significant levels of p53 protein. The other 19 samples including 6 cases with moderate or strong p53 staining were Bcl-2-unreactive or had minimal Bcl-2 reactivity similar to that observed in normal samples. Minimal Bcl-2 staining in 5 samples with moderate or severe dysplasia was only seen in the adjacent nondysplastic area. Our study shows that (1) some laryngeal keratoses strongly express Bcl-2 protein, (2) Bcl-2 expression does not appear to be dependent on p53, and (3) moderate or severe dysplasias may occur despite a decline in Bcl-2 expression.