Cytoplasmic Bcl-2 Research Articles

Flow cytometric immunophenotyping including Bcl-2 detection on fine needle aspirates in the diagnosis of reactive lymphadenopathy and non-Hodgkin's lymphoma

Fine-needle aspiration (FNA) with immunophenotyping by immunocytochemistry (IC) on cytospins has recently received increased consideration in the diagnosis of lymphoma. The aim of our study was to establish the diagnostic value of a four-color flow cytometric (FCM) panel, including cytoplasmic Bcl-2, in cytologic diagnosis of malignant non-Hodgkin's lymphoma (NHL) and reactive lymphoid hyperplasia (RH). We investigated 424 FNAs from 396 patients. FCM panel included lambda/kappa/CD19/CD5, CD23/CD10/CD20/CD19, CD4/CD7/CD8/CD3 and Bcl-2/CD10/CD19/CD3 in fluorescein isothiocyanate, phycoerythrin, and peridinin chlorophyll protein or a tandem conjugate of R-phycoerythrin and indodicarbocyanine and allophycocyanin. Bcl-2 expression was evaluated separately for gated B and T cells. In 97% of 172 RH samples, FCM was concordant with the diagnosis. FCM gave correct immunologic diagnosis in 95% of low-grade B-cell NHLs, 78% of high-grade B-cell NHLs, and 53% of T-cell lymphomas. Malignant B cells had higher Bcl-2 expression than did reactive B and T cells. This helped to establish a correct diagnosis especially in cases where no clear-cut monoclonality could be shown by kappa/lambda staining or where there was no expression of surface light chain. The highest Bcl-2 expression was found in follicular lymphomas. Our FCM panel allowed precise classification of NHL in FNA material in 89.5% of all samples. Bcl-2 staining can be recommended for primary differentiation between reactive hyperplasia and NHL.

Flow Cytometric Expression of bcl-2 by CD10+ B-Cells Reliably Distinguishes Follicular Lymphoma from Follicular Hyperplasia.

The diagnosis of follicular lymphoma (FL) is often straightforward in most biopsy specimens. In a minority of cases, however, a differentiation from follicular hyperplasia (FH) can be challenging, especially in small needle core biopsies. The difficulty can be compounded in cases of FL with non-diagnostic immunoglobulin light chain ratios and cases of lymphoma without any significant surface expression of either immunoglobulin kappa or lambda light chain. The expression of bcl-2 by follicle center B-cells is often used to distinguish FL from FH using immunohistochemistry. The interpretation of bcl-2 expression patterns by immunohistochemistry, however, can be difficult because of normal expression of bcl-2 by T-cells present in reactive lymphoid follicles and by normal expression of bcl-2 by mantle zone B-cells. We have utilized multiparameter flow cytometry to evaluate the expression of bcl-2 in cases of FL and FH with successful results. This study includes consecutive biopsy specimens from well-documented cases of FL (n = 12) and FH (n = 16). Other lymphoma types were not included. Cytoplasmic expression of bcl-2 was evaluated on CD10+CD19+ B-cells using permeabilization techniques on a four-color Beckman-Coulter Epics-XL flow cytometer. Appropriate controls were run in each case. All cases of CD10-expressing FL showed significant expression of bcl-2 by CD10+ B-cells in contrast to no significant expression of bcl-2 by CD10+ follicle center B-cells of reactive follicles (Positive predictive value, 100%; Negative predictive value, 100%). Although our patient population is small, the results indicate that the expression of cytoplasmic bcl-2 on CD10+ B-cells by flow cytometry reliably distingushes FL from FH using CD10 gating. This method is superior to immunohistochemical evaluation of bcl-2 in cases with CD10 expression. A minority of FL, however, do not show bcl-2 expression (not seen in our series) and such cases must be taken into consideration when evaluating a clonal B-cell population with CD10 but no bcl-2 expression.DIAGNOSISCD45+CD19+(%)CD45+CD19+CD10+(%)bcl2+(%) in CD10+ gateFL grade 1/3656538FL grade 1/3684467FL grade 1/3727299FL grade 1/3886299FL grade 2/3726899FL grade 1/3595995FL grade 1/3968494FL grade 1/3595995FL grade 1/3453899FL grade 2/3767476FL grade 1/3544790FL grade 2/3353498

Nuclear Partners of Bcl-2: Bax and PML

A milestone in understanding the functioning of the antiapoptotic cytoplasmic protein Bcl-2 was the discovery that Bcl-2 was capable of heterodimerising with the pro-apoptotic protein Bax at the mitochondrial level, creating a delicate balance of cell death preventing and promoting regulators. In recent years we identified substantial pools of Bcl-2 and Bax in nucleoplasm as well. We demonstrated that nuclear Bcl-2 controls cellular proliferation and, in an indirect manner, apoptosis. Sound support for functional presence of nuclear Bcl-2 and Bax would be evidence of Bcl-2-Bax binding in this compartment. Here we show by immunoprecipitation-using a battery of commercially available, monoclonal antibodies-that Bcl-2 binds Bax in nuclei of human breast cancer cells. Interestingly, findings by others pointed at an interaction between the product of the promyelocytic leukemia gene, the PML protein, and Bax. PML plays a part in cell proliferation and apoptosis, a rather similar role we assigned to nuclear Bcl-2. Nuclear Bcl-2, but not Bax, was found to immunoprecipitate with nuclear PML. These data show that binding of Bcl-2 with structurally and functionally related proteins extends to the nucleus, emphasizing its pivotal role in Bcl-2-mediated actions.

Expression of bcl-2 and bax in chewing tobacco-induced oral cancers and oral lesions from India.

Deregulation of oncogenes and tumor suppressor genes involved in apoptosis has been associated with tumor development and progression. To investigate the involvement of apoptosis regulating proteins in oral cancer in Indian patients, primarily associated with chewing tobacco habits, immunohistochemical expression of bcl-2 and bax was examined in 63 oral squamous cell carcinomas, and 31 putative premalignant lesions. Our studies revealed overexpression of tumor specific cytoplasmic bcl-2 in 56% and bax in 43% oral cancers. The oral cancers in the Indian patients are preceded by premalignant oral lesions; hence oral lesions were examined for bcl-2 and bax expression. We observed aberrant expression of bcl-2 in 16% oral lesions comprising leukoplakias and SMF and bax in 55% oral lesions. We have already reported, p53 expression in these oral cancers and lesions. It was noteworthy that 30% oral cancers demonstrated a p53+bcl2+ pattern, and 14% samples exhibited p53+bcl2+bax+ pattern. However, none of the oral lesions showed concurrent deregulation of p53 and bcl-2 or all the three genes. Interestingly 45% oral lesions were p53-bax+ as compared to 18% oral cancers; while 39% oral lesions were bcl2-bax+ as compared to 14% oral cancers, indicating overexpression of bax in oral lesions, in the absence of p53 and bcl-2 proteins. Significant correlation was observed between positive nodal status and bcl2+ (p=0.047) and p53+bcl-2+ (p=0.01) in oral cancers. Kaplan Meier survival analysis showed significantly (p=0.059) higher survival in patients with p53- oral tumors than with p53+ tumors. Our studies thus indicate frequent overexpression of apoptosis regulators bcl-2, bax and p53 proteins in oral cancers, and a subset of oral lesions, representing early events in oral car-cinogenesis. The aberrant bcl-2 expression and loss of p53 function observed, may play an important role in the tumorigenesis of oral cancers by allowing escape from apoptosis and enabling additional genetic alterations to accrue.

Studies of the mechanism of cytolysis by tumour-infiltrating lymphocytes.

In order to determine the mechanism of tumour destruction by tumour-infiltrating lymphocytes (TIL), we examined the ability of both CD4+ and CD8+ effector TIL, and TIL clones, to manifest granzyme-mediated and Fas-mediated destruction of tumour targets. In many in vitro studies TIL have been shown to manifest anti-tumour reactivity, yet many tumours escape immunological destruction. To investigate the role of Fas expression and the concomitant sensitivity to the inducibility of apoptotic death, we derived TIL from four melanomas and one glioma. The glioma, and all but one of the melanomas, expressed Fas, but Fas-mediated apoptosis could only be detected if the targets were treated with cyclohexamide. The melanomas and the glioma all expressed detectable cytoplasmic Bcl-2 protein, known to exert anti-apoptotic activity. Lysis of tumours by CD8-enriched cultures and CD8+ clones was Ca2+-dependent and could not be modified by an anti-Fas MoAb. In CD4-enriched cultures or CD4+ clones with cytotoxic potential against tumour cells, cytotoxicity was also Ca2+-dependent. As Ca2+-dependent cytotoxicity is usually the result of secretion of perforin/granzyme-B, we investigated the presence of perforin in cytotoxic CD4+ clones and demonstrated the presence of granular deposits of this enzyme in some of the CD4+ clones. Although an anti-Fas MoAb did not block the lysis of melanoma targets by CD4+ clones, the examination of Fas-dependent targets demonstrated that these clones also had the potential to kill by the Fas/Fas ligand system. These data suggest that the predominant mechanism in tumour killing by TIL appears to be perforin-granzyme-dependent, and that the solid tumour cell lines we studied are less susceptible to Fas-mediated apoptosis. As non-apoptotic pathways may enhance tumour immunogenicity, exploitation of the perforin-granzyme-dependent cytotoxic T lymphocyte (CTL) pathways may be important for achieving successful anti-tumour responses.

P53 and bcl-2 Overexpression as Associated Risk Factors in Patients 40 Years Old or Less with Transitional Cell Carcinoma of the Bladder

Objectives: Transitional cell carcinoma (TCC) of the bladder in younger patients has historically a favourable prognosis. bcl-2 and p53 genes are implicated in cell cycle regulation with roles on programmed cell death. Presence of nuclear accumulation of p53 and cytoplasmic accumulation of bcl-2 were proposed to confer a growth advantage to tumour cells. In this study, we investigated the roles of p53 and bcl-2 as prognostic factors in TCC of bladder in patients younger than 40 years. Patients and Methods: From 1986 to 1998, 25 patients younger than 40 years were treated for TCC of bladder in our hospital. Of the tumour specimens, 24 were adequate for evaluating p53 and bcl-2 oncoproteins (group I). As a control (group II), we randomly selected 30 patients older than 50 years treated for bladder cancer in this period. Two oncoproteins were detected by immunohistochemical analysis in paired tumour tissue specimens in both groups. Retrospectively obtained clinical follow-up data were available, with a mean follow-up of 44 and 25.5 months in groups I and II, respectively. Relations between tumour recurrences and progression with positivity of bcl-2 and p53 were investigated. Results: Expression of bcl-2 was observed in 13 (54.1%) and 11 (36.7%) and nuclear p53 accumulation in 9 (37.5%) and 17 (56.7%) of groups I and II, respectively. In the presence of p53 expression, tumours showed significantly more progression in group I (55 vs. 6.7%) and group II (41.1 vs. 0%). Recurrence rates were not significantly different in tumours with and without nuclear p53 overexpression in both groups. Also, recurrence and progression rates were not significantly different in tumours with and without cytoplasmic bcl-2 overexpression in both groups. Grade (G) and stage appeared as important prognostic factors in both groups since 60% of GIII tumours showed progression in group I, but none of GI and GII tumours. Similarly, 75% of T3 tumours progressed, while these rates were 25 and 25% for T1–T2 tumours in group I. In group II, 31.2, 25 and 0% of GIII, GII and GI tumours progressed, while 50, 41.6 and 0% of T3, T2 and T1 tumours progressed, respectively. Conclusions: Nuclear p53 expression in TCC appears to be associated with a poorer prognosis in both younger and older patients. Although cytoplasmic bcl-2 overexpression is found in the majority of tumours in the younger group, it is not associated with tumour progression and recurrence.

Routine Formaldehyde Fixation Irreversibly Reduces Immunoreactivity of Bcl-2 in the Nuclear Compartment of Breast Cancer Cells, but not in the Cytoplasm

Bcl-2 and Bax belong to a family of proteins involved in apoptosis regulation and are believed to reside in the cellular cytoplasm. The authors recently reported interphase nuclear localization of both proteins after immunofluorescence staining of formaldehyde- and methanol-fixed human and rodent cell monolayers. In addition, the authors' data confirmed earlier reports on Bcl-2 immunoreactivity of mitotic chromosomes in human cells. In their experience, nuclear or mitotic staining of Bcl-2, in contrast with cytoplasmic Bcl-2 immunoreactivity, is rarely observed in formaldehyde-fixed, paraffin-embedded breast cancer specimens. Therefore, the authors wondered if nuclear and mitotic Bcl-2 immunoreactivity could be irreversibly reduced by certain fixation procedures, including formaldehyde fixation. Here the authors investigated the effects of various routinely used fixation protocols and antigen retrieval techniques on Bcl-2 and Bax immunoreactivity in monolayers of MCF-7 human breast cancer cells. Whereas nuclear and mitotic immunoreactivity for Bcl-2 was clearly present after formaldehyde and methanol fixation, it was completely absent in cells fixed in acetone, methanol, or formaldehyde alone. In addition, it was found that in particular nuclear and mitotic Bcl-2, and to a lesser extent cytoplasmic Bcl-2 immunoreactivity, decreased after prolonged formaldehyde fixation, whereas Bax immunoreactivity diminished only slightly. Heat-mediated antigen retrieval after prolonged formaldehyde fixation elevated cytoplasmic, but not nuclear and mitotic, Bcl-2 immunoreactivity.

Routine Formaldehyde Fixation Irreversibly Reduces Immunoreactivity of Bcl-2 in the Nuclear Compartment of Breast Cancer Cells, but not in the Cytoplasm

Bcl-2 and Bax belong to a family of proteins involved in apoptosis regulation and are believed to reside in the cellular cytoplasm. The authors recently reported interphase nuclear localization of both proteins after immunofluorescence staining of formaldehyde-and methanol-fixed human and rodent cell monolayers. In addition, the authors' data confirmed earlier reports on Bcl-2 immunoreactivity of mitotic chromosomes in human cells. In their experience, nuclear or mitotic staining of Bcl-2, in contrast with cytoplasmic Bcl-2 immunoreactivity, is rarely observed in formaldehyde-fixed, paraffin-embedded breast cancer specimens. Therefore, the authors wondered if nuclear and mitotic Bcl-2 immunoreactivity could be irreversibly reduced by certain fixation procedures, including formaldehyde fixation. Here the authors investigated the effects of various routinely used fixation protocols and antigen retrieval techniques on Bcl-2 and Bax immunoreactivity in monolayers of MCF-7 human breast cancer cells. Whereas nuclear and mitotic immunoreactivity for Bcl-2 was clearly present after formaldehyde and methanol fixation, it was completely absent in cells fixed in acetone, methanol, or formaldehyde alone. In addition, it was found that in particular nuclear and mitotic Bcl-2, and to a lesser extent cytoplasmic Bcl-2 immunoreactivity, decreased after prolonged formaldehyde fixation, whereas Bax immunoreactivity diminished only slightly. Heat-mediated antigen retrieval after prolonged formaldehyde fixation elevated cytoplasmic, but not nuclear and mitotic, Bcl-2 immunoreactivity.

The angiogenic pathway "vascular endothelial growth factor/flk-1(KDR)-receptor" in rheumatoid arthritis and osteoarthritis.

Active angiogenesis, together with an up-regulation of angiogenic factors, is evident in the synovium of both rheumatoid arthritis (RA) and osteoarthritis (OA). The present study assessed, by immunohistochemistry, the microvessel density in the synovium of these arthritides and in normal controls, in relation to the expression of the angiogenic factors vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) and the apoptosis-related proteins bcl-2 and p53. More importantly, using the novel 11B5 MAb, the activated "VEGF/flk-1(KDR)-receptor" microvessel density was assessed. VEGF expression in fibroblasts was diffuse in both RA and OA. Diffuse PD-ECGF expression of fibroblasts was noted in all cases of RA, while fibroblast reactivity was focal in the OA material. The standard microvessel density (sMVD), as assessed with the anti-CD31 monoclonal antibody (MAb), was higher in RA (64+/-12) and in OA (65+/-16) than in normal tissues (52+/-8; p=0.008 and 0.0004, respectively). The activated microvessel density (aMVD), assessed with the 11B5 MAb, was significantly higher in RA (29+/-10) than in OA (17+/-4; p<0.0001) and than in normal tissues (14+/-2; p<0.0001). The "activation ratio" (aMVD/sMVD) was statistically higher in RA (0.46+/-0.17) than in OA and normal synovial tissues, the latter two having a similar ratio (0.28+/-0.08 and 0.26+/-0.03, respectively). Cytoplasmic bcl-2 expression was frequent in the synovial cells of OA, but rare in RA. Nuclear p53 protein accumulation was never observed. It is suggested that the angiogenic pathway VEGF/flk-1(KDR) may play an important role in the pathogenesis of RA and OA. Thus, failure of VEGF/flk-1(KDR) activation, in the presence of increased VEGF expression, may indicate a synovium with an impaired capacity to establish a viable vasculature, consistent with the degenerative nature of OA. On the other hand, the activated angiogenesis in RA shows a functional, still pathologically up-regulated VEGF/flk-1(KDR) pathway. Whether restoration of an impaired VEGF/flk-1(KDR) pathway in OA, or inhibition of this in RA, would prove of therapeutic importance requires further investigation.

Failure of Bcl-2 family members to interact with Apaf-1 in normal and apoptotic cells.

CED-9 blocks programmed cell death (apoptosis) in the nematode C. elegans by binding to and neutralizing CED-4, an essential activator of the aspartate-directed cysteine protease (caspase) CED-3. In mammals, the CED-9 homologs Bcl-2 and Bcl-xL also block apoptosis by interfering with the activation of CED-3-like caspases. However, it is unknown whether this occurs by binding to the CED-4 homolog Apaf-1. Whilst two groups previously detected an interaction between Bcl-xL and Apaf-1 in immunoprecipitates,1,2 another group found no interaction between Apaf-1 and any of ten individual members of the Bcl-2 family using the same experimental approach.3 In this study, we aimed to resolve this discrepancy by monitoring the binding of Apaf-1 to three Bcl-2 family members within cells. Using immunofluorescence and Western blot analysis, we show that whilst Apaf-1 is a predominantly cytoplasmic protein, Bcl-2, Bcl-xL and Bax mostly reside on nuclear/ER and mitochondrial membranes. This pattern of localization is maintained when the proteins are co-expressed in both normal and apoptotic cells, suggesting that Bcl-2, Bcl-xL or Bax do not significantly sequester cytoplasmic Apaf-1 to intracellular membranes. In addition, we confirm that Apaf-1 does not interact with Bcl-2 and Bcl-xL in immunoprecipitates. Based on these data, we propose that Apaf-1 is not a direct, physiological target of Bcl-2, Bcl-xL or Bax.

Follicular lymphoma can be distinguished from benign follicular hyperplasia by flow cytometry using simultaneous staining of cytoplasmic bcl-2 and cell surface CD20.

The distinction between benign follicular hyperplasia (FH) and follicular lymphoma (FL) is sometimes problematic. We wanted to determine whether the expression of bcl-2 of FH was quantitatively different from that of FL, using surface CD20 expression as a discriminator of the various lymphoid compartments. Lymph node cell suspensions from 12 cases of FH and 17 cases of FL were analyzed by flow cytometry using a combined surface CD20 and intracellular bcl-2 staining. CD20- T cells in FH demonstrated the same bcl-2 expression as the CD20+ mantle cells, but the bright CD20+ germinal center cells showed near absence of bcl-2 expression. In contrast, the neoplastic cells of FL showed greater bcl-2 expression than the T cells of the same tumors and all cell populations of FH. This difference was particularly significant between the neoplastic B cells of FL and the germinal center cells of FH. The combined analysis of CD20 and bcl-2 should be useful for the differential diagnosis between FH and FL and particularly applicable to limited samples or when B-cell clonality is in question. Whether the quantitation of bcl-2 expression can be of further discriminatory value in malignant lymphomas remains to be determined.

Bcl-2 and Bax proteins are present in interphase nuclei of mammalian cells.

The Bcl-2 family of proteins comprises both cell death inhibiting and cell death promoting members, generally believed to be cytoplasmic and predominantly membrane-associated. Like Bcl-2, many Bcl-2-related proteins contain a C-terminal membrane insertion domain and much research is aimed at evaluating the functional role of their localization to the outer membranes of mitochondria, the endoplasmic reticulum, and perinuclear membranes. However, confocal fluorescence microscopy of human breast cancer cells and rat colon cancer cells immunostained with commercial antibodies raised against different epitopes of the anti-apoptotic Bcl-2 and the pro-apoptotic Bax protein revealed that these proteins are not only present in the cellular cytoplasm, but also within interphase nuclei. This was confirmed by Western blot analysis of isolated nuclei. In human cells, certain epitopes of Bcl-2, but not of Bax, were also found to be associated with mitotic chromatin. Anti-estrogen treatment of human breast cancer cells or transfection with antisense bcl-2 led to a reduction in both cytoplasmic and nuclear Bcl-2. Transfection of human bcl-2 and bax into rat cells resulted in cytoplasmic and nuclear Bcl-2 and Bax. This data seems in line with increasing evidence that the role of the Bcl-2 family of proteins should be extended to activities inside the nuclear compartment.

Combined role of tumor angiogenesis,bcl-2, and p53 expression in the prognosis of patients with colorectal carcinoma

The objective of this study was to evaluate intratumoral neoangiogenesis in Dukes Stage B and Stage C (AJCC/UICC Stage I and III) colorectal adenocarcinoma and its correlation with nuclear p53 oncoprotein accumulation and cytoplasmic bcl-2 expression as well as to assess the prognostic significance of these features in patient outcome. Paraffin embedded specimens from 55 patients with Dukes Stage B (AJCC/UICC Stage I) and 51 patients with Dukes Stage C (AJCC/UICC Stage III) colorectal adenocarcinoma who were treated with surgery were assessed. Patients with lymph node involvement (Dukes Stage C [AJCC/UICC Stage III]) also were treated with postoperative pelvic radiotherapy and adjuvant chemotherapy with 5-fluorouracil and leucovorin with or without interferon-alpha. Immunohistochemistry was performed using the anti-CD31 monoclonal antibody (MoAb) for vessel staining, the DO7 MoAb for nuclear p53 expression, and the clone 124 for cytoplasmic/perinuclear bcl-2 expression. Patient follow-up ranged from 4-70 months (median, 28 months). High vascular grade (microvessel score [MS] >/= 40) was observed in 39 of 106 specimens (37%), a medium MS (16-39) was observed in 29 of 106 cases (27%), and a low MS (7-15) was observed in 38 of 106 cases (36%). Positive expression of the bcl-2 protein in > 10% of cells was observed in 33 of 106 cases (31%), whereas p53 nuclear oncoprotein accumulation in > 10% of cells occurred more frequently (44 of 106 cases [42%]). No correlation among p53 expression, bcl-2 expression, and vascular grade was observed. Stroma infiltration by CD31 positive lymphocytes was associated strongly with increased vessel density (P = 0.0001). In univariate analysis Dukes stage was the only significant prognostic parameter (P = 0.02), whereas p53 and vascular grade showed marginal prognostic significance (P = 0.07 and P = 0.09, respectively). In Dukes Stage C (AJCC/UICC Stage III) patients, high vascular grade was the only parameter that predicted a worse overall survival (P = 0.04). Double stratification showed that patients with high vascular grade and positive p53 expression had a poorer survival (P = 0.03). The results of the current study suggest that p53 mutations, loss of bcl-2 expression, and tumor angiogenesis are events linked to the processes of metastases and local invasion in patients with colorectal carcinoma. Increased vascularization appears to be the most important prognostic factor in patients with Dukes Stage C (AJCC/UICC Stage III) colorectal adenocarcinoma.

Localization of survival motor neuron protein in human apoptotic-like and regenerating muscle fibers, and neuromuscular junctions.

Mutations in the gene encoding survival motor neuron (SMN) protein are found in > 98% of patients with autosomal-recessive spinal muscular atrophy. We investigated the possible role of SMN in normal and abnormal human muscle by immunostaining biopsies of 20 patients with various neuromuscular diseases using monoclonal antibodies against SMN. SMN was strongly expressed cytoplasmically in chronic peripheral neuropathies, in about 80% of chronically denervated, very atrophic muscle fibers containing clumps of TUNEL-positive pyknotic nuclei: about 60% of those fibers also had cytoplasmic Bcl-2 and Bax immunoreactivity. In regenerating muscle fibers of various myopathies SMN co-localized with desmin, Bcl-2 and Bax; it was also present at the postsynaptic domain of normal human neuromuscular junctions. Thus, SMN may play a role in normal and pathological processes of adult human muscle fibers.

Bcl-2 protein expression is associated with a prognostically favourable phenotype in breast cancer irrespective of p53 immunostaining.

A role for altered programmed cell death in cancer stems from the description of alterations on tumour-associated genes involved in the regulation of apoptosis such as p53 and bcl-2. The balance between the latter may have significant implications for the pathobiology of breast cancer. This study was therefore undertaken to evaluate the expression of these two gene products with opposite functions. A total of 142 paraffin-embedded tumour blocks were evaluated for nuclear p53 (a marker of p53 inactivation) and cytoplasmic bcl-2 immunohistochemistry. The results were semiquantitated. The bcl-2 protein was found within the infiltrating neoplastic cells of 97 (68%) specimens but it was also detectable in tumours' in situ compartments and in benign mammary tissue. We identified a strong correlation between bcl-2 immunoreactivity and oestrogen receptor positivity (P = 0.03), while bcl-2 expression also correlated significantly with small tumour size (P = 0.006) and low nuclear grade (P = 0.01), but it did not correlate with the expression of p53. bcl-2 presence tended to diminish with disease progression (P = 0.06). Quantitatively increased bcl-2 immunostaining was significantly associated with older patients (P = 0.02) as well as with presence of progesterone receptors (P = 0.01). Thirty-seven tumours (26%) were judged positive for p53 protein expression. The p53 positivity status was independent of all classical histopathological variables; however, high p53 expression was negatively linked to oestrogen receptors (P = 0.005). In breast cancer, bcl-2 protein is associated with a prognostically favourable phenotype and appears to be related to hormonal regulation, rather than to disabled p53 gene function.

Expression of Bcl-2 by human bone marrow mast cells and its overexpression in mast cell leukemia.

Bcl-2 protein plays a major role in the prevention of programmed cell death of differentiating cells. In the present study, the expression of cytoplasmic bcl-2 by human Bone Marrow Mast Cells (BMMC) from both normal and pathological bone marrow samples was examined. A total of 35 subjects corresponding to 9 healthy volunteers, 8 cases of adult indolent systemic mast cell disease (SMCD), 4 cases of pediatric mastocytosis (PM), 11 cases of hematological malignancies (HM), 2 cases of reactive bone marrow, and 1 case of mast cell leukemia (MCL) were analyzed. The expression of bcl-2 was studied using quantitative three-color flow cytometry. We also studied the molecular configuration of the bcl-2 gene and other relatives by Southern blot and polymerase chain reaction (PCR) in the MCL case. Bcl-2 expression was detected in BMMC from all samples analyzed. No significant differences on the expression of bcl-2 were detected between BMMC from healthy subjects and patients with SMCD, PM, HM, and reactive bone marrow. By contrast, bcl-2 protein was overexpressed in BMMC from MCL patient without gene rearrangement. Our results show that bcl-2 protein was constitutively expressed by BMMC. BMMC from MCL display overexpression of bcl-2, which could not be related to molecular rearrangements involving the bcl-2 gene. The expression of this protein by mature MC may play a role in the prevention of MC apoptosis and thus help to explain the long survival of these cells. The overexpression of bcl-2 by BMMC in MCL may help to explain their resistance to chemotherapy-induced apoptosis.

Detection of intracellular antigens by flow cytometry: comparison of two chemical methods and microwave heating

Detection of intracellular antigens by flow cytometry requires effective fixation and permeabilization of the cell membrane. This study compares three fixation/permeabilization techniques: two commercial chemical reagents, the ORTHOPermeaFix (OPF) and the FIX&PERM Cell Permeabilization Kit (F&P), and a novel method based on microwave heating (MWH). They have been applied to the detection of two nuclear (p53 and rb/p105) and two cytoplasmic (bcl-2 and mdr-1/gp-170) antigens, using positive- and negative-control cell lines and peripheral blood mononuclear cells. Western blotting was performed as a control of protein expression. For the four antigens assessed, cellular morphology, discrimination between intact cells and debris, percentage of positive cells, and mean fluorescence intensity were examined. For this last parameter, the assessment of the MWH technique was performed using SD and a graphical approach inspired by the concepts described by Bland and Altman (Lancet 1986;346: 1085-7) as well as Petersen et al. (Clin Chem 1997;43: 2039-46). The statistical analysis shows that MWH is comparable to the commercial methods and that its reproducibility is also equivalent to OPF and F&P. As assessed for some of the most clinically relevant intracytoplasmic and intranuclear antigens, the MWH method appears to be a valuable and inexpensive alternative. It is worth noting that, unlike commercial reagents, MWH altered surface antigens. Interestingly, this feature, which would prevent cell selection on the basis of combined membrane and intracellular epitopes, is associated with a decrease of nonspecific background fluorescence.

Correlation of proliferation indices, apoptosis, and related oncogene expression (bcl-2 and c-erbb-2) and p53 in proliferative, hyperplastic, and malignant endometrium

Background: The various morphological groupings of endometrial pathology are often difficult to distinguish from each other. The endometrium is an actively proliferating tissue and there is an overlap in cell proliferation fraction (CPF) between benign proliferative endometrium (BPE) and endometrial carcinoma (EC). Apoptosis in benign cycling endometrium is related to the menstrual cycle. In this study we evaluated CPF, apoptosis, and oncogenes that relate to cell turnover (bcl-2, p53, and c-erbB-2) in the spectrum of endometrial pathology. Methods: We examined a total of 64 cases consisting of 10 cases of BPE, 18 cases of simple endometrial hyperplasia (SEH), 18 cases of complex hyperplasia (CEH; including eight cases with atypical hyperplasia), and 18 cases of EC, FIGO grade 1. CPF was measured by the mitotic index (MI) and by the percentage of Ki-67 positive nuclei (Ki-67 index). Apoptotic index (AI) was determined on hematoxylin and eosin sections. Results: MI was 2.48% in BPE, 0.65% in SEH, 0.6% in CEH, and 0.91% in EC (P < .00001). Ki-67 index was 38.44%, 16.4%, 23.25%, and 31.7% respectively (P < .00001). Al was 1.17%, 2.2%, 2.57%, and 3.31% respectively (P = .02). The AI/MI and AI/Ki-67 ratios were lowest in BPE and highest in SEH (P = .007). All cases of BPE, 84% of SEH cases, 77% of CEH cases, and 88% of EC cases displayed cytoplasmic and/or nuclear bcl-2 expression. Cytoplasmic bcl-2 expression increased from BPE to SEH, whereas it decreased in CEH and EC with emergence of only nuclear expression. Of the EC cases, 38.8% showed intense nuclear bcl-2 reactivity and a significantly higher Ki-67 index than cases with cytoplasmic expression (P = .01). No p53 or c-erbB-2 expression was seen in either BPE or EH. Of the EC cases, 50% were positive for p53 whereas 30% were positive for c-erbB-2. C-erbB-2-positive cases had a significantly higher Ki-67 index and AI than negative cases (P = .02). Cases of EC with p53 expression also had significantly higher AI (P = .01). Conclusions: In actively proliferating tissues like endometrium, CPF does not correlate with progression to malignancy. In contrast, AI and derived AI/CPF ratios are better indicators of progression. The expression of p53, c-erbB-2, and nuclear bcl-2 in EC correlate with higher cell turnover indices (CPF and AI).

Bcl-2 and p53 overexpression as associated risk factors in transitional cell carcinoma of the bladder.

Bcl-2 and p53 genes are implicated in cell cycle regulation with roles on programmed cell death. Consequently, presence of Bcl-2 and nuclear accumulation of p53 were proposed to confer a growth advantage tumour cells. We have investigated their role as prognostic factors in fresh tumour samples from a cohort of twenty patients with transitional cell carcinoma of the bladder by immunohistochemical analysis in paired specimens. Expression of Bcl-2 was observed in 11 cases (69%) and nuclear p53 accumulation in 9 (45%). In the presence of Bcl-2 protein expression, tumours showed a slightly higher rate of recurrence (55% vs. 40%) and significantly more progression (36% vs. 0%). Recurrence and progression rates were not significantly different in tumours with and without nuclear p53 overexpression (recurrence rates 56% vs. 55% and progression rates 33% vs. 27%, respectively). Grade and stage appeared as important prognosticators since 75% of grade 3 tumours showed recurrence and 50% progressed in contrast to 44% and 13%, respectively, of grades 1 and 2 tumours. Similarly, 50% of Ta-T1 tumours recurred and 20% progressed, while these rates were 75% and 75% for T2-T3 tumours. Also, expression of Bcl-2 and nuclear accumulation of p53 correlated with grade. In grade 3 tumours, 75% showed nuclear p53 overexpression and 80% cytoplasmic Bcl-2 protein. These figures were 25% and 64% for grades 1 and 2 tumours. In conclusion, Bcl-2 protein expression in transitional cell carcinoma appears to be associated with a poorer prognosis and together with nuclear p53 overexpression they are associated with tumour de-differentiation.

Bcl-2 expression and prognosis of patients with endometrial carcinoma.

Bcl-2 protein inhibits apoptosis, reduces the requirement for growth factors, and thereby extends the survival of cells. Recent findings of Bcl-2 in several solid tumors suggest that it might contribute to the genesis of some types of cancer. Over-expression of Bcl-2 might play a role in carcinogenesis and malignant progression of endometrial carcinoma. The aims of this study were to determine Bcl-2 expression in endometrial carcinoma in relation to other histopathologic prognostic factors, and to test its prognostic significance in patients with endometrial carcinoma. A total of 61 endometrioid-type endometrial carcinomas were immunohistochemically investigated for Bcl-2 expression on cryostat sections. Bcl-2 localization was observed in cytoplasm in 18 tumors, in nucleus in 27 tumors, or in both in 5 tumors. In 11 tumors, Bcl-2 was observed neither in cytoplasm nor in nucleus. There was not a statistically significant relationship between grade of tumor and Bcl-2 expression. Cytoplasmic Bcl-2 became less frequently expressed as the tumor invaded the myometrium deeper (p < 0.025). Retroperitoneal lymph-node dissection was performed in 57 patients. Multiple-regression analysis showed that lymph-vascular space invasion and nuclear expression of Bcl-2 were correlated to pelvic lymph-node metastasis (p < 0.0001 and < 0.05 respectively). Univariate Cox regression analysis revealed that nuclear Bcl-2 expression was associated with shorter survival (p < 0.05) than that of patients with cytoplasmic Bcl-2 expression. Pelvic node metastasis was a significant prognostic factor for patients who underwent systematic retroperitoneal lymph-node dissection. Cox multivariate-regression analysis revealed that pelvic node metastasis and cervical invasion were the most important prognostic factors in this series of patients. When the analysis was made after exclusion of pelvic node metastasis, histologic grade (hazard ratio = 2.4), cervical invasion (hazard ratio = 3.7) and nuclear Bcl-2 expression (hazard ratio = 11.5) were shown to be significant predictors of survival of the patients. These results indicate that aberrant Bcl-2 expression might be involved in malignant progression of endometrioid-type endometrial carcinoma. Site of Bcl-2 localization may be an important predictor of prognosis for patients with endometrioid-type endometrial carcinoma.