Utility of microdissection and polymerase chain reaction for the detection of immunoglobulin gene rearrangement and translocation in primary intraocular lymphoma

OBJECTIVE

Primary intraocular lymphoma, a non-Hodgkin's lymphoma, is a primary central nervous system lymphoma (PCNSL). Diagnosis is usually made by identifying malignant, large B lymphocytes in the vitreous, eye, brain, and cerebral spinal fluid; however, these cells are few, friable, and difficult to recognize. Recently, clonal heavy chain immunoglobulin (IgH) gene rearrangement and bcl-2 gene translocation have been reported in systemic B-cell lymphoma and are used for the detection of malignant cells and in making a diagnosis. The authors investigated the molecular changes in three eyes and a chorioretinal biopsy specimen of four patients with PCNSL.

DESIGN

Human tissue study.

MATERIALS

Five ocular specimens of PCNSL were collected.

INTERVENTION

The first patient had a diagnostic enucleation of the left eye. The second patient underwent diagnostic chorioretinal biopsy. In the third case, a pair of autopsied eyes with reactive lymphoplasmacytic infiltrates of a patient with acquired immune deficiency syndrome (AIDS) were studied. In the fourth case, an enucleated eye of a patient with AIDS-associated lymphoma was sampled.

MAIN OUTCOME MEASURES

The bcl-2 and IgH genes of the lymphoma cells from routine, paraffin-embedded, formaldehyde-fixed, or frozen histologic tissue sections were analyzed using microdissection and polymerase chain reaction (PCR) technique.

RESULTS

Lymphoma cells obtained from the above four cases showed IgH rearrangement gene in the third framework of the VH region. Bcl-2-associated translocation also was detected in three cases (cases 1, 2, and 4).

CONCLUSION

Rearrangement of the IgH gene can serve as a molecular marker for PCNSL. Microdissection allows for procurement and analysis of specific, selected, minute cell populations that are obtained from histologic sections of the complex, heterogeneous tissue. Translocation of IgH and bcl-2, the apoptotic "survival" signal and proto-oncogene, could contribute to the pathogenesis of PCNSL. The combination of microdissection and PCR is a powerful tool for studies of small lesions and cell populations and for understanding disease mechanisms.

Modulation of Bcl-2 expression: a potential component of estrogen protection in NT2 neurons

Neuroprotective effects of estrogen have been demonstrated against a variety of cytotoxic insults. We present data here addressing a possible mechanism of estrogen neuroprotection in the human teratocarcinoma cell line NT2 terminally differentiated to a neuronal phenotype. Cell death induced by H2O2 or glutamate results in a dose-dependent cell death of NT2 neurons, while 24 h of estrogen pretreatment significantly enhances neuronal viability. Bcl-2 expression has been shown to reduce oxidative stress and prevent cell death. In NT2 neurons, Bcl-2 levels are dramatically elevated upon differentiation and are further enhanced with estrogen treatment. These results suggest that neuroprotective effects of estrogen may be related to increases in Bcl-2 expression.

Mutation analysis of CD95 (APO-1/Fas) in childhood B-lineage acute lymphoblastic leukaemia

The CD95 system plays an important role in lymphocyte homeostasis, has been implicated in the development of lymphoid malignancies, exerts a tumour suppressor function, and contributes to drug-induced cytotoxicity. We hypothesized that mutations of CD95 may occur in childhood B-lineage acute lymphoblastic leukaemia (ALL), a disease known for its constitutive resistance towards CD95-mediated apoptosis. We investigated 32 primary B-lineage ALL of childhood and five B-lineage ALL cell lines. All primary leukaemias expressed CD9 5 and bcl-2 to a variable degree. Most of the leukaemias were resistant towards CD95-mediated apoptosis. However, using SSCP analysis, no mutations in the coding and proximal promoter region could be detected. We conclude that the resistance towards CD95-mediated apoptosis observed in most de novo B-lineage ALL is not caused by mutations of the CD95 death receptor.

[Expression of p53 and bcl-2 in colorectal adenomas and carcinomas]

Recent publications have associated p53 and bcl-2 genes in the process of neoplastic transformation. As the colonic adenoma-carcinoma sequence is an adequate natural model for carcinogenesis, it was considered interesting to analyze the expression of bcl-2 and p53 in these neoplasms. Seventy three adenomatous polyps (adenomas) and 60 adenocarcinomas of the colon and rectum were studied. Adenomas showed mild dysplasia in 16, moderate in 27, severe in 15 and focal carcinoma in the remaining 15. Adenocarcinomas surpassed the deep muscle layer in every case and were moderately differentiated. The studied gene expression was analized immunohistochemically using antibodies bcl-2 from Dako and p53 from Novocastra, both at a 1:100 dilution. Cytoplasmic stain for bcl-2 and nuclear stain for p53 above 10% of the cells were considered positive for each gene respectively. Results showed that there was accumulation of p53 protein in 26/58 (45%) adenomas with different grades of dysplasia. This result is similar to the reactivity found in adenomas with focal carcinoma where 8/15 (53%, p = 0.4) were positive but different from adenocarcinomas which were positive in 47/60 (78%, p = 0.0001). Regarding bcl-2, positivity was found in 53/73 (73%) of all the adenomas whereas adenocarcinoma showed expression in 14/60 (23%, p = 0.0000). When adenomas were grouped according to their degree of dysplasia and the existence of focal carcinoma, a diminishing frequency of reactivity for bcl-2 was found and when adenomas with three different grades of dysplasia were fused together, 47/58 (81%) were positive and this was compared with adenomas having focal carcinoma, 6/15 (40%) and with adenocarcinoma, 14/60 (23%), they showed significant differences (p = 0.001 and p = 0.0000 respectively). The analysis of the frequency of expression for both genes studied in the different lesions described yielded an inverse relation between them. This study allows the conclusion that the expression of bcl-2 is an early event in carcinogenesis and that it is replaced by mutation of p53 as the neoplastic change progresses.

Role of the bcl-2/bax pathway in hepatocyte apoptosis during acute rejection after rat liver transplantation

It is well established that hepatocytes undergo apoptotic cell death in the course of rejection of liver grafts. The present study was designed to investigate the role of the bcl-2/bax pathway in liver allograft tissue. Orthotopic liver transplantation was performed in three groups of rats: group 1, a syngeneic combination (Lewis to Lewis), group 2, an allogeneic combination (ACI to Lewis), and group 3, an allogeneic combination (ACI to Lewis) treated with 15-deoxyspergualin. The number of apoptotic cells identified by the TUNEL method in the grafted liver reflected the severity of acute rejection. In group 1, both bcl-2 mRNA and bax mRNA were expressed in trace amounts. In group 2, bcl-2 mRNA was slightly expressed while the expression of bax mRNA rose steadily. In group 3, bcl-2 mRNA expression levels remained similar to group 1, while bax expression levels exceeded those in group 1, but were less than in group 2. Expression of bcl-2 mRNA was stationary in comparison with expression of bax mRNA. Significantly higher levels of bax mRNA were expressed from day 4 in group 2 than in group 1 (on postoperative days 4, 6, and 8, P < 0.05, group 2 vs group 1). We also investigated bax protein and results consistent with the mRNA analysis data were obtained. These findings suggest that apoptotic cell death in liver allograft rejection is regulated, at least in part, by bax.

Expression of bcl-2 homologue mRNAs in rat liver allograft: rejection-induced cell apoptosis is associated with upregulation of bax and bcl-xs expression

Apoptosis is considered to play an important role in rejection of organ transplants, although the precise mechanism has not been elucidated. In this study, we screened for the expression of bcl-2 homologues (bcl-2, bax, bcl-xl, and bcl-xs) and Fas ligand (FasL) by RT-PCR method in grafts during acute rejection in rats following liver transplantation. Both bax and bcl-xs (inducers of apoptosis) mRNA levels increased steadily in the allografted group from postoperative day (POD) 2 to 8, while no remarkable changes of bcl-2 and bcl-xl expression (inhibitors of apoptosis) were recognized. Significant induction of FasL gene expression was observed in the allografted group on POD 4 and expression gradually decreased thereafter, although minimal FasL mRNA expression was seen in isografts. Our results indicated, for the first time, that rejection-induced cell apoptosis is closely associated with upregulation of bax and bcl-xs expression besides FasL, but not with down-regulation of bcl-xl.

Expression of bcl-2 in testicular carcinoma: correlation with tumor progression and MDR1/Pgp

BACKGROUND

The expression of bcl-2 has been studied extensively in a variety of human tumors. However, there is a lack of clinical data regarding its expression in germ cell testicular tumors (GCTTs).

METHODS

In this study, the authors screened 70 patients with GCTTs for bcl-2 expression using immunohistochemistry (IHC) and the streptavidin-biotin-alkaline phosphatase method. This expression was also correlated with the metastatic behavior, clinical stages, and multidrug resistance gene product protein (MDR1/Pgp) immunostaining of GCTTs.

RESULTS

Overall, 41 carcinomas (58%) stained positively with anti-bcl-2 monoclonal antibody. According to histologic type, these lesions with positive staining included 11 of 26 seminomas (42.3%) and 30 of 44 nonseminomatous germ cell testicular tumors (NSGCTs) (68%). The incidence of bcl-2 immunostaining was higher (P = 0.05, two-tailed Fisher's exact test) among NSGCTs than among seminomas. The expression of bcl-2 was more prevalent among tumors from patients with metastases than among tumors from metastasis free patients (P = 0.000). There was a significant difference between the three stages of disease in the expression of bcl-2 (chi2 = 0.000), i.e., bcl-2 expression was clearly dominant among tumors at advanced stages. A significant association between bcl-2 and Pgp immunostaining was established (P = 0.004).

CONCLUSIONS

These findings revealed that bcl-2 expression occurs in GCTTs. Furthermore, they suggest that bcl-2 is associated with a more advanced malignant phenotype of this tumor.

Interferon-alpha enhances CD95L-induced apoptosis of human malignant glioma cells

CD95 ligand (CD95L)-induced apoptosis is a novel immunotherapeutic approach to malignant glioma. Here, we report that interferon-alpha (IFN-alpha) sensitizes LN-229 and T98G human malignant glioma cells to CD95L-induced apoptosis. In contrast to the effects of IFN-gamma and TNF-alpha which sensitize glioma cells to CD95 antibody-induced apoptosis in part by enhancing CD95 expression, IFN-alpha has no effect on CD95 expression at the cell surface of LN-229 and T98G cells. To confirm that changes in CD95 expression are not required for the effects of IFN-alpha, we show that IFN-alpha enhances CD95L-induced apoptosis even in CD95-transfected LN-308 glioma cells. These LN-308 cells have little endogenous CD95 expression but express high levels of CD95 from a stably integrated CD95 expression plasmid. The sensitizing effects of IFN-alpha appear to be independent of cell cycle effects of IFN-alpha and are unaffected by ectopic expression of the bcl-2 proto-oncogene. IFN-alpha enhances CD95L-induced activation of caspase-3, a critical mediator of CD95L-induced cell death. IFN-alpha also increases the cytotoxic effects of BCNU, teniposide and cytarabine in both cell lines, and of vincristine in LN-229 cells. Doxorubicin and 5-fluorouracil toxicity are unaffected by IFN-alpha. IFN-alpha may be a useful adjunct to novel strategies of immunochemotherapy for malignant gliomas that target CD95-mediated apoptosis.

[Bcl-2/JH gene re-arrangement determined by PCR as a means to detect minimal residual disease in malignant lymphomas]

OBJECTIVE

To develop a sensitive method to detect minimal residual disease and to elucidate the significance of bcl-2 gene rearrangement in diagnosis and therapy of malignant lymphoma.

METHODS

Using polymerase chain reaction(PCR) to detect bcl-2 gene rearrangement and using serial dilution method to define the sensitivity of PCR.

RESULTS

In 9 different malignant lymphoma cell lines, Su-DHL-4 and Su-DHL-6 were shown bcl-2(MBR)/JH rearrangement, the sensitivity of PCR was 1:10(5). In 16 patients with follicular lymphoma, the peripheral blood and bone marrow were PCR positive in 4 both at initial diagnosis and after complete remission.

CONCLUSION

Detection of bcl-2 gene rearrangement by PCR provides a sensitive and specific assay of minimal residual disease. It helps improve staging of disease, stratification and evaluation of treatment.

The extent of proliferative and apoptotic activity in intraductal and invasive ductal breast carcinomas detected by Ki-67 labeling and terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labeling

BACKGROUND

The balance among cell proliferation, cell differentiation, and cell death determines the cell number in a population as well as the size or even the stage of a tumor. Thus, to improve our understanding of the pathogenesis of neoplasms, it is important to investigate the regulation of both cell proliferation and cell death.

METHODS

This study examined the occurrence of apoptosis and proliferative capacity in 46 breast carcinomas: 20 intraductal carcinomas (ductal carcinomas in situ [DCIS]) and 26 infiltrative ductal carcinomas (IDC). Terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labeling (TUNEL) and immunostaining with the Ki-67 antibody were used in the examination. A ladder of DNA fragments induced by apoptosis was demonstrated by means of DNA agarose gel electrophoresis in 10 of the available TUNEL positive and negative samples.

RESULTS

The results were correlated with p53, bcl-2, estrogen receptor (ER), and progesterone receptor (PR) protein expression, which would suggest association with apoptosis by immunohistochemistry. The apoptosis and proliferation of each cancer were expressed as the number of tumor cells undergoing apoptosis and proliferation per 1000 tumor cells. The extent of apoptosis was more frequently observed in DCIS than in IDC (21.9+/-6.8 vs. 4.0+/-0.9, P < 0.001), and the proliferation activity was significantly higher in IDC than in DCIS (16.8+/-6.5 vs. 3.5+/-0.8, P < 0.006). Apoptosis associated with MIB-1 positive cells and TUNEL labeling was significantly higher in IDC than in DCIS (3.26 vs. 0.42, P=0.001). In DCIS, apoptosis was correlated with p53 (r=0.663, P=0.005), and p53 had a reverse correlation with bcl-2 (r=0.620, P= 0.018). Moreover, bcl-2 expression was associated with ER (P=0.028) and PR (P= 0.005) expression in both DCIS and IDC.

CONCLUSIONS

The results of this study show that a higher degree of apoptosis and lower proliferation activity in intraductal carcinoma result in a steady-state, self-renewing condition in which net growth of the tumor is rare. The results also indicate that apoptosis was altered by the expression of p53, bcl-2, ER, and PR.

Polymerase chain reaction diagnosis of t(14;18) from paraffin-embedded tissues fixed with Holland Bouin fluid

The t(14;18) translocation and its molecular counterpart, the bcl-2/IgH gene rearrangement, are highly characteristic of follicular non-Hodgkin lymphomas. The identification of the tumor-specific t(14;18) clone is mandatory for any molecular studies on residual disease because of the existence of circulating t(14;18)-bearing benign cells. In this study, the ability to specifically polymerase chain reaction (PCR) amplify t(14;18) with DNA purified from tissues fixed with Holland Bouin fluid is demonstrated. The specificity of the PCR product was confirmed by internal probe hybridization and with comparison of the nucleotidic sequences of this PCR product with those obtained from the corresponding frozen material. Although the sensitivity of the technique is 50% to 60%, paraffin-embedded tissues fixed with bouin fluid may be a good alternative to frozen tissues to detect t(14;18) in tumors.

Regulators of proliferation and apoptosis in carcinoma of the larynx

Expression of interrelated gene products regulating cell proliferation and apoptosis may be disordered in squamous cell carcinoma (SCC) of the larynx compared with normal squamous mucosa. Certain of these abnormalities, alone or in combination, may be of prognostic significance in low-stage carcinomas of the larynx. A retrospective study of archival material was made. Expression of the Bcl-2 family of apoptosis-related genes (bcl-2, bcl-X, mcl-1, and bax) and the proliferation- and apoptosis-related genes p53 and cyclin D-1 were determined in 40 low-T-stage laryngeal carcinomas and in uvular epithelium from patients without SCC. Among the antiapoptotic members of the Bcl-2 family, Bcl-X and Mcl-1 showed more intense and widespread staining than Bcl-2 itself in both normal squamous mucosa and SCC. The well-ordered expression patterns of Bcl-2-related proteins found in normal epithelium were lost in SCC, and patterns of expression varied widely among individual tumors. Also, mean expression levels for Bax and cyclin D-1 were significantly lower than in normal epithelium (P = .036 and P = .009, respectively), whereas expression of p53 was higher in tumors (P = .034). Expression of Bcl-X and Mcl-1 was greater in poorly differentiated than in well-differentiated tumors (P = .014 and P = .031, respectively). No associations were seen between marker expression patterns and clinical outcome in this group of patients. Bcl-x and Mcl-1 appear to be the most abundantly expressed antiapoptotic proteins of the Bcl-2 family in both normal squamous mucosa and SCC of the larynx. Multiple genes regulating proliferation and apoptosis are expressed abnormally in laryngeal SCC compared with normal epithelium. In particular, loss or measurable decrease in expression of the proapoptotic protein Bax in tumors may contribute to the deranged growth control of SCC. Further study is needed to evaluate the prognostic significance of particular patterns of disordered expression of proteins regulating proliferation and apoptosis in SCC of different head and neck sites.

Activation of bcl-2 suppressible 40 and 44 kDa p38-like kinases during apoptosis of early and late B lymphocytic cell lines

Activation of several different kinases characterizes the induction of apoptosis. Abelson virus transformed pre-B lymphocytes undergo apoptosis within 24 h of serum deprivation, PKA activation or gamma-irradiation, and the activity of two kinases of ca. 40 and 44 kDa is specifically induced during this apoptotic process. Bcl-2 expression prevents both apoptosis and the induction of these kinases. Immunologic and substrate similarities indicate that these kinases are related to the p38 family of MAP kinases. More mature cells of the B lymphocytic lineage, plasmacytomas, also exhibit induction of these kinases when apoptosis is induced by withdrawal of serum or IL-6. Treatment of the pre-B cells with ICE protease inhibitors when apoptotic stimuli are delivered prevents induction of the kinase activity, and partially inhibits apoptosis. These findings indicate that the induction of these 40 and 44 kDa p38 related kinases is a common feature of apoptosis in mouse B lymphocytic cells and may represent a step downstream of ICE proteases in the signal cascade that leads to programmed cell death.

Apoptosis regulating genes in prostate cancer (review)

Prostatic adenocarcinoma is emerging as a major cause of morbidity and mortality in the male population in the western world. Programmed cell death (apoptosis) in the prostate is activated by hormone ablation and is under the control of several regulating genes including the tumour suppressor gene p53 and the proto-oncogene bcl-2. Bcl-2 belongs to a rapidly expanding family of genes which form two functionally antagonistic groups controlling cell death and survival. Apoptosis regulating genes appear to play an important role in the development and progression of prostatic adenocarcinoma and offer a potential target for future therapeutic strategies.

Molecular characterization of Warthin tumor

OBJECTIVE

Warthin tumor of the salivary gland is composed of oncocytic epithelium with a prominent follicular lymphoid infiltrate. The purpose of this study was to characterize the clonality of this lymphoid component by means of polymerase chain reaction technology.

STUDY DESIGN

DNA was isolated from paraffin-embedded tissue from 20 cases of typical Warthin tumor of the salivary gland and amplified by polymerase chain reaction to assess B- and T-cell clonality.

RESULTS

No dominant clonal populations were identified in any tumor. However, minor clonal expansions of both B and T cells were detected in up to 50% of tumors (immunoglobulin H, 50%; T-cell antigen receptor beta, 10%; T-cell antigen receptor gamma, 5%). No tumors showed evidence of bcl-2 proto-oncogene translocation, whereas 95% contained detectable Epstein-Barr virus DNA.

CONCLUSION

The B- and T-cell components of Warthin tumor are polyclonal with oligoclonal expansion of both T and B cells in some lesions.

Controlled proliferation by multigene metabolic engineering enhances the productivity of Chinese hamster ovary cells

The eukaryotic cell cycle is regulated by a complex network of many proteins. Effective reprogramming of this complex regulatory apparatus to achieve bioprocess goals, such as cessation of proliferation at high cell density to allow an extended period of high production, can require coordinated manipulation of multiple genes. Previous efforts to establish inducible cell-cycle arrest of Chinese hamster ovary (CHO) cells by regulated expression of the cyclin-dependent kinase inhibitor (CDI) p21 failed. By tetracycline-regulated coexpression of p21 and the differentiation factor CCAAT/enhancer-binding protein alpha (which both stabilizes and induces p21), we have achieved effective cell-cycle arrest. Production of a model heterologous protein (secreted alkaline phosphatase; SEAP) has been increased 10-15 times, on a per cell basis, relative to an isogenic control cell line. Because activation of apoptosis response is a possible complication in a proliferation-arrested culture, the survival gene bcl-xL was coexpressed with another CDI, p27, found to enable CHO cell-cycle arrest predominantly in G1 phase. CHO cells stably transfected with a tricistronic construct containing the genes for these proteins and for SEAP showed 30-fold higher SEAP expression than controls.

Genomic structure and domain organisation of the human Bak gene

The Bcl-2 homologue, Bak, is a potent inducer of apoptosis. FISH data presented here located the gene to 6p21.3. Mapping was consistent with its location centromeric of the HSET locus and approximately 400kb from the MHC. The construction of a contig of genomic clones across the locus facilitated the sequencing of a PAC containing the gene. Comparison of the gene structure to functional and physical domains revealed a good agreement between the physical structure and the intron-exon organisation. The position of a single intron was conserved in comparison to other members of the Bcl-2 family, namely Bax, CED-9, Bcl-X and Bcl-2, but all other introns were displaced, consistent with a divergent phylogeny.

Apoptosis, bcl-2 expression, and proliferative activity in human endometrial stroma and endometrial granulated lymphocytes

Human endometrial leukocytes undergo regular cyclical changes during the menstrual cycle, with a striking increase in the phenotypically unusual population of CD56+ CD16- endometrial granulated lymphocytes (eGLs) in the late secretory phase and early pregnancy. The factors that regulate this increase in eGL numbers are unclear; their unusual morphology, however, has led to the suggestion that they undergo apoptosis at the end of the menstrual cycle. Apoptosis, bcl-2 expression, and proliferative activity were examined in the stroma of normal cycling, progesterone-treated, and early-pregnancy endometrium. The expression of bcl-2 and the Ki67 proliferation marker by highly purified (> 98% CD56+) eGLs from endometrium during the menstrual cycle and from first-trimester decidua was also studied. Apoptotic cells were rarely observed in the endometrial stroma of any of the samples examined. Stromal bcl-2 expression, however, increased from the proliferative to the premenstrual phase, and double immunohistochemical labeling demonstrated large numbers of bcl-2+ CD56+ eGLs. In contrast, Ki67 expression was high in the endometrial stroma during the proliferative phase, fell during the secretory phase, and rose again premenstrually, because of expression by eGLs. Isolated CD56+ eGLs also showed high bcl-2 and Ki67 expression at the end of the menstrual cycle. Unlike premenstrual endometrium, progesterone-treated endometrium and first-trimester decidua contained few proliferating cells, expressed high levels of bcl-2, and showed no evidence of apoptosis. Thus, eGLs do not undergo apoptosis in premenstrual endometrium, and their regulatory mechanisms remain to be clarified.

Evidence of apoptosis in human carotid atheroma

PURPOSE

Apoptosis is a morphologically distinct form of programmed cell death that plays a major role in cellular development and homeostasis. In this study, we examined the role that apoptosis may have in the pathogenesis of atherosclerosis.

METHODS

We examined immunohistochemically 20 normal carotid arteries and the carotid arteries of 86 patients (mean age, 68 years; range, 52 to 80 years) who underwent atherectomy for primary atherosclerosis. The expression of two genes, BCL2, which inhibits apoptosis, and BAX, which induces apoptosis, was examined and correlated to the presence of risk factors that included hypertension, smoking, hyperlipidemia, and diabetes mellitus.

RESULTS

BAX expression was found in 26 of 86 cases (30%), and no immunoreactivity was found in the normal carotid specimens. BCL2 expression was not seen in any examined tissues (atherosclerotic or normal carotid arteries). Of the 26 patients who expressed the BAX gene, 22 were hypertensive (85%), and hypertension (>160/95 mm Hg) was present in 25 of 60 patients (41%) who did not express the BAX gene (p < 0.01). No significant correlation was found between the expression of the BAX gene and other risk factors (smoking, hyperlipidemia, diabetes mellitus) or presenting symptoms.

CONCLUSIONS

In a significant number of stenosed carotid arteries (30%), we found no evidence of apoptosis suggested by the presence of BAX expression. Hypertension was more prevalent in those patients with BAX gene expression than in those patients without BAX gene expression. BCL2 expression, which inhibits apoptosis, was not found. Further study of this phenomenon may contribute to the discovery of new treatments for atherosclerosis.

Lac/Tet dual-inducible system functions in mammalian cell lines

The Escherichia coli Lac repressor (Lac system) and tetracycline responsive promoter (Tet system) systems have been used individually to regulate gene expression at the cellular as well as the organismal levels. In this study, these two systems were combined (designated Lac/Tet dual-inducible system) to regulate two inducible genes simultaneously in a single cell. The isopropyl-beta-D-thiogalactopyranoside (IPTG) and tetracycline (used for the operation of the Lac and the Tet systems) were non-cytotoxic to the cells when added together into the cells at around the optimal concentrations (IPTG: < or = 5 mM; tetracycline: < 1.5 micrograms). The rate and efficiency of induction and repression of two inducible genes regulated by the Lac/Tet dual-inducible system were similar to the results obtained when one inducible gene is regulated by one inducible system in a single cell. The Lac/Tet dual-inducible system could function in many cell lines, which was demonstrated by regulating the expression of beta-galactosidase and luciferase reporter genes in five tumor cell lines by transient transfection analysis. The feasibility of introducing a second inducible system into an already established inducible cell line was confirmed. Finally, we showed that the Lac/Tet dual-inducible system functions at translational and at functional levels in a stable cell line named 7-4-b, which contains the Ha-ras and bc1-2 inducible genes. In conclusion, this study extends the application of prokaryotic inducible systems from the regulation of a single gene to two genes and helps clarify the relationship between two genes and the effects of two genes on the cells.

Expression of bcl-2 and bcl-X in bladder cancer

PURPOSE

TP53 and RB1 gene mutations in bladder transitional cell carcinoma (TCC) are correlated with grade, stage, recurrence, and survival and may correlate with tumor cell apoptotic potential. Overexpression of the bcl-2 and bcl-X anti-apoptotic genes has been correlated with poor prognosis and chemotherapy resistance in other systems. Similar studies have not been performed in TCC. We thus sought to determine expression of bcl-2 and bcl-X in TCC and correlate these with stage, survival and abnormal pRb or p53 expression.

MATERIALS AND METHODS

Forty-two TCC samples (19 Ta and 23 locally advanced tumors) and normal urothelial controls were examined. Immunohistochemistry for p53, pRb, bcl-2 and bcl-X was performed on an automated system using indirect streptavidin biotin/horseradish peroxidase staining. Western immunoblot analysis was performed on bladder cancer cell lines to further characterize bcl-X expression. Recurrence-free and disease-specific survival were retrospectively determined. Kaplan-Meier survival curves were compared using the log rank test, and correlation of abnormal staining with stage and p53 or pRb status was determined using Fisher's exact test.

RESULTS

Bcl-2 was expressed in less than 1% of normal urothelial cells, but moderate expression of bcl-x was found in all normal urothelial samples. Only 7.0% of TCC samples (1/19 Ta and 2/23 locally advanced tumors) demonstrated bcl-2 overexpression. Bcl-X overexpression was observed in 45.2% of TCC (8/19 Ta and 11/23 locally advanced tumors). Western blot analysis also revealed that both the long (29 kDa) anti-apoptotic form and short (19 kDa) pro-apoptotic form were overexpressed in bladder cancer cell lines and normal human urothelial cells. Bcl-X overexpression was weakly correlated with normal p53 expression (p = 0.06). There were no correlations of bcl-2 and bcl-X overexpression with abnormal p53, pRb, or tumor stage. There were no differences in recurrence-free or overall survival in patients with abnormal bcl-X staining.

CONCLUSIONS

Bcl-2 overexpression is rare in TCC. Bcl-X overexpression is common, likely reflecting its expression pattern in normal urothelium, but is not correlated with stage or abnormal p53 or pRb staining. Within the power limitations of this small study, bcl-X overexpression is not correlated with recurrence or survival.

Tumour growth and cell kinetics in variants of a human endometrial adenocarcinoma expressing either wild-type or mutant p53

We have compared the baseline cell proliferation and tumour growth in two variants of a human endometrial adenocarcinoma grown in nude mice. One of these tumour variants expressed wild-type p53 whereas the other had mutations of the p53 gene at codon 175 in both alleles and at codon 248 in one allele. There was no difference in growth rate between the tumour variants. Cell proliferation parameters, such as labelling index and S-phase fraction, were significantly increased in the tumour with mutated p53 and consequently there was a significantly lower proportion of cells in the G1-phase, proposing an at least partial loss of suppressor function in this tumour. Semi-quantitative analysis of the p53 and bcl-2 proteins showed a significant overexpression of p53 and a decreased expression of the bcl-2 protein in the p53 mutated tumour variant compared with the variant with wild-type p53. We conclude that wild-type p53 protein acts as an active suppressor in the regulation of the baseline growth and cell kinetics of this tumour and could be linked through a p53--bcl-2 system in human endometrial adenocarcinomas.

Detection of single and associated lesions of the Bcl-1, Bcl-2, Bcl-6, c-myc, p53 and p16 genes in B-cell non-Hodgkin's lymphomas: value of molecular analysis for a better assignment of the histologic subtype

BACKGROUND AND OBJECTIVE

Molecular genetic abnormalities have been frequently described in non-Hodgkin's lymphomas (NHL). These lesions have been associated with specific entities, allowing a better categorization of NHL. However, these abnormalities are not as specific as initially described and their association is still unknown.

DESIGN AND METHODS

By Southern blot and polymerase chain reaction, we have simultaneously analyzed the proto-oncogenes Bcl-1, Bcl-2, Bcl-6, c-myc and MLL and the tumor suppressor genes p53 and p16, in 100 unselected B-cell NHL patients at diagnosis, to establish its incidence throughout the different NHL subtypes, defined both by Working Formulation and REAL classifications, and to assess the frequency of co-existence of two or more genetic lesions within each individual patient.

RESULTS

Fifty two cases displayed some genetic abnormality. Bcl-1, altered in 12 cases, was highly specific to mantle cell lymphomas (57% of them), but 6 cases had a different histologic subtype. Bcl-2 was rearranged in 26 cases: 70% in follicular lymphomas (FL) and 20% in diffuse large cell lymphomas; these abnormalities were also present in other subtypes, i.e. marginal lymphomas (30%). Bcl-6 abnormalities were mostly found in diffuse large cell lymphomas (29%) but also found in other subgroups, like FL (14%). C-myc rearrangements were specific to Burkitt's lymphoma. MLL gene was always germline. Deletions and/or rearrangements of p53 and p16 genes were rare (4% and 8% of all cases, respectively). Finally, association of genetic lesions was a relatively common finding (13% of cases), especially in cases with adverse prognostic morphologies according to the REAL.

INTERPRETATION AND CONCLUSIONS

Molecular abnormalities are frequent in NHL at diagnosis, not only as unique lesions but also associated. A relative high specificity of some alterations was seen, thereby contributing to a better assessment of the histological subtype.

Ratio of bcl-xshort to bcl-xlong is different in good- and poor-prognosis subsets of acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous collection of leukemic disorders ranging from chemotherapy-sensitive subsets [inversion 16 and t(8;21)], which often can be cured with cytosine arabinoside alone, to the most resistant subsets, which can survive even supralethal levels of combination alkylator chemotherapy (cytogenetic subsets monosomy 5 and monosomy 7).

MATERIALS AND METHODS

To analyze the expression of BCL-2 family genes, which are expressed in these subsets of AML, we used PCR sequence amplification reactions that are dependent on oligonucleotide primers representing the BH1 and BH2 homology domains to generate the unique regions between BH1 and BH2. These primers are conserved among all members of the BCL-2 gene family and are separated by a 150 nucleotide region sequence between the BH1 and BH2 domains. The PCR products unique to each BCL-2 family member were cloned directionally into sequencing vectors. The identity of the insert of each clone was determined by slotblots of the DNA amplified from individual colonies and by hybridization with radioactive probes specific to the bcl-2, bcl-x, or bax genes.

RESULTS

We found that bcl-2 is the predominant member expressed in AML samples with a poor prognosis (-5, -7), whereas the transcripts of bcl-x are higher than those of bcl-2 in the AML samples with a good prognosis [inv16, t(8;21)]. No significant difference in bax expression was detected between AML subsets of good and bad prognosis. The ratio of bcl-xlong, which inhibits apoptosis, to bcl-xshort, which promotes apoptosis, was determined by amplification with a pair of primers specific to bcl-x followed by separation of the PCR product on agarose gels. Bcl-xlong and bcl-xshort appeared as bands of different molecular mass on a molecular weight gel and were visualized by ethidium bromide staining or Southern blot analysis with a bcl-x-specific probe.

CONCLUSIONS

We found that the ratio of bcl-x long to bcl-x short was higher in the AML patients with a poor prognosis. These experiments showed that the levels of BCL-2 family members in the leukemia cells of good- and poor-prognosis subsets are different. In addition, novel members of the BCL-2 family were isolated from the cells of AML patients of either prognosis.

Mitochondria and apoptosis

Programmed cell death serves as a major mechanism for the precise regulation of cell numbers and as a defense mechanism to remove unwanted and potentially dangerous cells. Despite the striking heterogeneity of cell death induction pathways, the execution of the death program is often associated with characteristic morphological and biochemical changes, and this form of programmed cell death has been termed apoptosis. Genetic studies in Caenorhabditis elegans had led to the identification of cell death genes (ced). The genes ced-3 and ced-4 are essential for cell death; ced-9 antagonizes the activities of ced-3 and ced-4, and thereby protects cells that should survive from any accidental activation of the death program. Caspases (cysteine aspartases) are the mammalian homologues of CED-3. CED-9 protein is homologous to a family of many members termed the Bcl-2 family (Bcl-2s) in reference to the first discovered mammalian cell death regulator. In both worm and mammalian cells, the antiapoptotic members of the Bcl-2 family act upstream of the execution caspases somehow preventing their proteolytic processing into active killers. Two main mechanisms of action have been proposed to connect Bcl-2s to caspases. In the first one, antiapoptotic Bcl-2s would maintain cell survival by dragging caspases to intracellular membranes (probably the mitochondrial membrane) and by preventing their activation. The recently described mammalian protein Apaf-1 (apoptosis protease-activating factor 1) could be the mammalian equivalent of CED-4 and could be the physical link between Bcl-2s and caspases. In the second one, Bcl-2 would act by regulating the release from mitochondria of some caspases activators: cytochrome c and/or AIF (apoptosis-inducing factor). This crucial position of mitochondria in programmed cell death control is reinforced by the observation that mitochondria contribute to apoptosis signaling via the production of reactive oxygen species. Although for a long time the absence of mitochondrial changes was considered as a hallmark of apoptosis, mitochondria appear today as the central executioner of programmed cell death. In this review, we examine the data concerning the mitochondrial features of apoptosis. Furthermore, we discuss the possibility that the mechanism originally involved in the maintenance of the symbiosis between the bacterial ancestor of the mitochondria and the host cell precursor of eukaryotes, provided the basis for the actual mechanism controlling cell survival.

Pore formation domain of human pro-apoptotic Bax induces mammalian apoptosis as well as bacterial death without antagonizing anti-apoptotic factors

A trace amount of the pro-apoptotic factor human Bax was sufficient to kill host Escherichia coli (Asoh, S., Nishimaki, K., Nanbu-Wakao, R., and Ohta, S., submitted). The region of Bax lethal to E. coli cells was determined by introducing truncated human bax mutant genes. A peptide corresponding to amino acid residues 115 to 144 of Bax was the smallest peptide capable of inducing cell death of E. coli. A truncated bax gene (Bax112-192) containing the region lethal to E. coli was then introduced into a murine promyeloid cell line, FDC-P1. Constitutively expressed Bax112-192 induced apoptosis as judged by decrease of transfectants surviving and DNA fragmentation. These results indicate that Bax112-192 contains the region directly responsible for mammalian apoptosis as well as bacterial death. Flow cytometric analysis by FITC-Annexin V showed that the transfectant cells expressing Bax112-192 or native Bax became apoptotic even without external stimuli. The apoptotic population in the cells expressing Bax112-192 was not decreased by co-expression of Bcl-2 or Bcl-XL, while Bcl-2 or Bcl-XL suppressed apoptosis in the cells expressing native Bax. Therefore, Bax induces apoptosis by its own activity without blocking the anti-apoptotic activity involved in Bcl-2 or Bcl-XL.

Genetic alterations in the development of mammary and prostate cancer in the C3(1)/Tag transgenic mouse model

We have generated a transgenic mouse model in which female mice develop ductal mammary adenocarcinomas and male mice develop prostatic adenocarcinomas by using a transgene containing the hormone-responsive rat prostatic steroid binding protein 5' flanking region C3(1) fused to the simian virus 40 (SV40) large T antigen. We have identified some genetic alterations during mammary and prostate tumor progression: (i) p53 is functionally inactivated during mammary cancer development without p53 mutations; (ii) Alterations in apoptosis during mammary tumor progression are p53 and bcl-2 independent; (iii) Ha-ras mutations occur early in the development of prostate cancer. This unique animal model offers the opportunity to study multistep tumorigenesis in these organs.

The anti-apoptosis bcl-2 proto-oncogene is preferentially expressed in limbic structures of the primate brain

By virtue of its capacity to prevent apoptosis the protooncogene bcl-2 is believed to play a crucial role in CNS development. Studies in rodents have shown that the anti-apoptosis Bcl-2 protein is widely expressed during CNS development, but undergoes a marked down-regulation during maturation and is present only at low concentrations in adult CNS. In contrast, current data suggest that Bcl-2 protein in adult monkey brain results from microglial expression. In the present immunohistochemical study, however, numerous subsets of Bcl-2-immunoreactive neurons were encountered in the amygdala, hippocampus, hypothalamus, limbic cortices and striatum of squirrel monkeys. Of particular interest was the presence in the basal portion of the amygdala and adjoining piriform cortex of numerous intensely immunoreactive cells with long and thick immunopositive processes that ran into the ventral amygdalofugal pathway. At striatal level Bcl-2-positive neurons were strictly confined to calbindin-poor striosomes, which are specifically innervated by limbic cortices. This study has provided the first evidence for the occurrence of Bcl-2 in mature monkey brain. It has further shown that this protein is preferentially expressed in limbic structures in primate forebrain. The sustained expression of this anti-apoptosis protein may protect limbic system neurons from various injuries or neurodegeneration. It may also be involved in the functional and structural changes that occur throughout adulthood in some regions of the primate limbic system.

Expression of bcl-2 in invasive and in situ carcinoma of the uterine cervix

OBJECTIVE

The oncoprotein bcl-2 inhibits apoptosis. The purpose of this study was to assess the expression of bcl-2 in human cervical carcinoma and to correlate this with clinicopathologic parameters.

STUDY DESIGN

Immunohistochemical staining for bcl-2 protein (MoAB clone 124) was performed on operative tissue specimens from 22 patients with carcinoma in situ of the cervix and from 137 patients with invasive cervical carcinoma (International Federation of Gynecology and Obstetrics stages I to IV). The immunoreactivity of bcl-2 was scored as positive (> or = 5% staining cells) or negative (< 5% staining cells).

RESULTS

Eighty-two percent of in situ carcinomas and 61% of invasive cervical carcinomas were bcl-2 positive. Expression of bcl-2 was correlated to tumor stage (p < 0.001) and to presence of vascular (p < 0.005) or lymphatic tumor (p < 0.023) permeation. In univariate analysis there was a strong relationship between bcl-2 expression and overall survival (p < 0.001). In multivariate analysis bcl-2 expression (p < 0.001), International Federation of Gynecology and Obstetrics stage (p = 0.011), and presence of lymphatic permeation (p = 0.014) proved to be independent prognostic factors.

CONCLUSIONS

Expression of bcl-2 is lost during tumor progression and is a strong prognostic parameter, suggesting that the regulation of apoptosis plays an important role in the behavior of cervical carcinomas. Better understanding of the mechanisms involved may lead to improved medical treatment strategies.

Retinoic acid induces apoptosis-associated neural differentiation of a murine teratocarcinoma cell line

Incubation with all-trans retinoic acid (RA) induces PCC7-Mz1 embryonic carcinoma cells to cease proliferation and to develop into a tissue-like pattern of neuronal, astroglial, and fibroblast-like derivatives over a period of several days. Concomitant with the induction of differentiation by RA, a sizable fraction of the Mz1 stem cells detaches and dies, with the maximal level of cell death achieved after 10 h of RA treatment. This RA-induced cell death fulfills all criteria of apoptosis, including nuclear condensation, intranucleosomal DNA degradation, expression of cysteine aspases (caspases), and the formation of apoptotic bodies. Apoptosis could be suppressed by the pan-caspase inhibitor zVAD-fmk (benzyloxycarbonyl-valinyl-alaninyl-aspartyl fluoromethyl ketone). Induction of apoptosis required at least 2 h of incubation with RA and followed the same RA concentration (EC50 = 10(-7) M RA) and time dependence as the induction of differentiation as delineated by the expression of the neuron-specific protein kinase C substrate GAP-43. RA-induced apoptosis increased with the plating density of PCC7-Mz1 cells. This effect was not due to deprivation of an essential nutrient or factor from the medium because apoptosis was not significantly affected by an increase of the concentration of fetal calf serum. In addition to RA, apoptosis could be induced by DNA-damaging treatment (UV light, cisplatin, methanesulfonic acid methyl ester) and cell cycle-arresting agents (hydroxyurea) as well as by serum depletion. Because inhibition of transcription and translation caused cell death efficiently even in the presence of serum, the synthesis of apoptosis-inhibiting factors by the cultured cells is indicated. Neither ApoI/Fas antibody nor glutamate induced apoptosis. Mz1 cells that have entered a differentiation pathway in response to RA treatment become increasingly less sensitive to apoptosis. This may be due in part to the expression of the bcl-2 proto-oncogene, which was detectable on the mRNA and protein level beginning 4 days after the addition of RA. The intracellular signaling pathway leading to apoptosis does not involve conventional or novel members of the protein kinase C gene family. Neither activation of protein kinase C by phorbol esters (phorbol 12,13-dibutyrate) nor inhibition by specific inhibitors (GF109203X, Gö 6976) and long-term treatment with phorbol 12,13-dibutyrate, in the presence or absence of RA, significantly influenced the amount or rate of apoptosis of PCC7-Mz1 cells. We conclude that the apoptotic activity following RA treatment of cultured PCC7-Mz1 cells probably is controlled by the same cascade of gene regulatory events that govern the early cell lineage determinations in this in vitro model system of neural development.

Suppression of apoptosis by bcl-2 does not prevent p53-mediated control of experimental metastasis and anchorage dependence

Mutations in the p53 tumor suppressor gene are frequently associated with the metastatic stage of tumor progression. Inactivation of p53 was shown to promote metastasis under experimental conditions. To determine the p53 functions that are involved in the control of tumor metastasis, we compared properties of three types of transformed mouse fibroblasts: with intact p53, with p53-mediated apoptosis suppressed by bcl-2 and with p53 inactivated by dominant negative mutants. Although expression of bcl-2 blocked apoptosis in detached cells and increased tumor cell survival in the blood circulation, it was insufficient to affect the ability of p53 to cause cell cycle arrest in detached cells and suppress experimental metastasis. For the suppression of metastasis complete inactivation of p53 was required. We conclude that the apoptotic function of p53 is dispensable for the p53-dependent suppression of experimental metastasis that is presumably achieved by controlling anchorage dependence. These data provide a possible explanation to dramatic differences in values of bcl-2 and mutant p53 as prognostic markers in human cancer.

Comparative study of invasive squamous cell carcinoma and verrucous carcinoma of the oral cavity: expression of bcl-2, p53, and Her-2/neu, and indexes of cell turnover

Significant clinical and biological differences are found between invasive squamous cell carcinoma (SCCA) and verrucous carcinoma (VC) of the oral cavity. The correct diagnosis of these tumors has important therapeutic implications. Immunoperoxidase stains for bcl-2, p53, and Her-2/neu, and in situ end-labeling of DNA to identify apoptosis were performed in eight VC and eight SCCA matched for age, sex, and stage. Marked differences were identified in the pattern of expression of oncogenes and the indexes of cell turnover in these two types of tumors. VC displayed minimal apoptosis in rare keratinizing cells (0 to 3%); p53-positive cells (4/8) and Ki-67 (8/8) were confined to the nuclei of the basal proliferating layers; and bcl-2 (4/8) was expressed only in the cytoplasm of rare tumor cells. In contrast, SCCA displayed higher apoptosis rates (5 to 10%), whereas p53- (5/8) and Ki-67- (8/8) positive nuclei were distributed randomly throughout the tumor. Very well differentiated areas in one SCCA case had a pattern of staining for p53 and Ki-67 similar to the one seen in VC. In SCCA bcl-2 showed patchy cytoplasmic staining (4/8) or strong cytoplasmic and nuclear positivity (2/8) in the less differentiated tumors. Her-2/neu was negative in all VC and SCCA cases. The different levels and patterns of gene expression and cell turnover between SCCA and VC undoubtedly correlate with the different biology and prognosis of these tumors.

Analysis of bcl-2 in sporadic breast carcinoma

BACKGROUND

The bcl-2 gene encodes a protein that blocks apoptosis and might help to promote tumor development. It is expressed in a high percentage of breast tumors and is associated with good prognostic features. However, the mechanisms that regulate bcl-2 expression in breast carcinoma are unknown. Moreover, immunohistochemical detection of bcl-2 is related inversely to p53 expression. This notwithstanding, the immunohistochemical detection of p53 does not always correlate with the detection of p53 gene mutations. The authors studied the molecular organization of bcl-2 as well as the methylation status of its CpG island and analyzed the correlation between bcl-2 expression and p53 gene mutations.

METHODS

The molecular organization of the bcl-2 gene and the methylation pattern of its CpG island were analyzed by Southern blot analysis. In addition, immunohistochemical analysis of bcl-2 and p53 protein expression was performed. Finally, the presence of mutations at exons 5-9 of the p53 gene were analyzed by polymerase chain reaction and single-strand conformation polymorphism.

RESULTS

No molecular abnormality was found at the bcl-2 locus in cases of sporadic breast carcinoma. Moreover, loss of heterozygosity analysis failed to detect any allelic loss in the study cases. It also was found that the bcl-2 CpG island was demethylated in all cases. These results point to a lack of correlation between bcl-2 protein expression and the presence of p53 gene mutations.

CONCLUSIONS

The level of bcl-2 expression in breast carcinoma is not associated with any somatic abnormality or epigenetic change at the bcl-2 locus. Conversely, although bcl-2 expression is related inversely to p53 protein expression, the analysis of p53 mutations (limited to exons 5-9) failed to demonstrate any relationship between p53 mutations and bcl-2 protein expression.

t(14;18) chromosomal translocation in follicular lymphoma: an event occurring with almost equal frequency both at the D to J(H) and at later stages in the rearrangement process of the immunoglobulin heavy chain gene locus

bcl-2/IgH fusion is considered a genetic error which occurs at the diversity (D) to joining (J(H)) stage of the gene rearrangement process in the immunoglobulin heavy chain (IgH) gene locus. Translocations of the bcl-2 protooncogene to the IgH locus at ontogenetically later IgH gene rearrangements are thought to represent exceptions. In the present study we analysed the junctional nucleotide sequence of 18 bcl-2/IgH fusion genes identifiable by polymerase chain reaction performed on DNA extracted from diagnostic lymph node tissue of 14 follicular lymphoma patients. In all clones studied, segments of variable length were found interposed between bcl-2 and J(H) gene sequences. Nucleotide sequence data analysis and comparisons performed with the corresponding germline sequences using the GenBank/EMBL database revealed the presence of D segments in most of the bcl-2/IgH fusion genes under study (13/18). By the same kind of computer-aided analysis, previously unrecognized D segments were identified in many published junctional sequences. These results suggest that bcl-2/IgH fusion events are very prevalent in rather more differentiated stages in B-cell ontogeny than previously recognized.

In vitro activation of low-grade non-Hodgkin's lymphoma by murine fibroblasts, IL-4, anti-CD40 antibodies and the soluble CD40 ligand

The in vitro analysis of growth regulation in low-grade B non-Hodgkin's lymphoma (B-NHL) is hampered by the rapid apoptotic death of the malignant B cells ex vivo. A complex culture system, using murine CDw32 transfected fibroblasts (LTK-cells), IL-4 and anti-CD40 mAb, has been established for the propagation of normal mature B cells in vitro. We investigated the influence of the different components of this coculture system on cell survival and apoptosis of B-NHL cells. Nine samples from patients with follicular lymphoma and from eight patients with immunocytoma were analyzed. No cell proliferation of B-NHL cells could be induced in the culture system. However, CDw32-transfected murine fibroblasts most efficiently supported cell viability of B-NHL cells with an increase in cell survival by 114% compared to the control (P = 0.047). IL-4 alone also had a stimulatory effect on cell survival of B-NHL cells after 6 days. In contrast, the soluble recombinant CD40 ligand gp39 and the anti-CD40 mAbs mAb89 and EA-5 did not prolong cell survival. CDw32 transfectants blocked apoptosis of B-NHL cells efficiently from 67% in the control to 16% (P = 0.001). Reduction in apoptosis was accompanied by an elevated bcl-2 protein expression. IL-4 or mAb89 did not further reduce apoptotic cell death in CDw32 transfectant-dependent cocultures. Our data underline the pivotal role of LTK- cells for cell survival of B-NHL cells in vitro. The efficient blockage of apoptosis associated with increased bcl-2 protein expression causes prolonged cell viability of the B-NHL cells.

Activation of the metaphase checkpoint and an apoptosis programme in the early zebrafish embryo, by treatment with the spindle-destabilising agent nocodazole

We have studied the developmental activation of the metaphase checkpoint, and the consequences of activating this checkpoint, in the zebrafish embryo. (1) Treatment with nocodazole (a microtubule destabiliser) before mid-blastula transition (MBT) produces complete destruction of all nuclei in the deep cell layer of the embryo. In contrast, nocodazole treatment after MBT efficiently produces metaphase arrest in this cell layer. Thus, the metaphase checkpoint becomes activated at MBT. (2) Although a metaphase arrest is induced by nocodazole, it is not induced by paclitaxel (a microtubule stabiliser). Thus the metaphase checkpoint appears to sense a destabilisation, but not a stabilisation, of spindle microtubules. (3) Metaphase-arrested cells (in nocodazole) can be driven into the next interphase by adding the Ca2+-specific ionophore A23187. Thus, a Ca2+-signalling pathway lies downstream of, or parallel to, the metaphase checkpoint. (4) After mid-gastrula stage, treatment with nocodazole produces DNA fragmentation in all three cell layers. In the enveloping epithelial monolayer (EVL), this is associated with a classical apoptotic phenotype. In the deep layer, it is associated with an unusual, highly condensed nuclear state that is entered directly from metaphase arrest. Thus, after the mid-gastrula stage, the embryo responds to nocodazle by undergoing apoptosis. (5) Nocodazole-induced apoptosis in the deep cell layer can be blocked by the caspase-1,4,5 inhibitors Ac-YVAD-CHO and Ac-YVAD-CMK. This suggests that a homologue of the C. elegans ced-9-ced-4-ced-3 pathway is involved in control over apoptosis in the early zebrafish embryo.

Immunohistochemical demonstration of bcl-2 protein in ameloblastoma

The bcl-2 gene is known through its product, bcl-2 protein, which prevents apoptosis, and also by its expression in development, especially in sites characterized by epithelial-mesenchymal interactions. In the developing tooth germ, bcl-2-protein is expressed in the epithelial component. In this study, we examined the expression of bcl-2 protein immunohistochemically in 25 ameloblastomas using a monoclonal antibody against anti-human bcl-2 oncoprotein. In all 25 cases, bcl-2 protein was found mainly in the outer layer of tumor cells, whereas the inner cells (stellate reticulum-like cells and squamoid cells) were negative. The bcl-2 protein is therefore thought to play a role in maintaining the stem-cell population in the peripheral layers of the tumor nests from which proliferating cells can be recruited.

Clinical and molecular aspects of motoneurone diseases: animal models, neurotrophic factors and Bcl-2 oncoprotein

Animal models of motor neurone disease (MND) are being increasingly used for screening molecules with clinical potential. A number of different treatments to decrease the progression of neuronal cell loss have been proposed; these include: Bcl-2 (B-cell leukaemia oncogene-2), neurotrophic factors, glutamate receptor inhibitors and Ca2+ channel antagonists. In this review Yves Sagot, Richard Vejsada and Ann C. Kato focus on the effects of neurotrophic factors and Bcl-2, both of which have been shown to prevent cell death in various experimental paradigms. Studies performed in animal models of MND have confirmed the potential of these molecules to support motoneurone survival. Some of them have been shown to act in synergy and these results are discussed in the context of molecular mechanisms leading to collaborative and synergistic activities, and also with respect to presumptive subpopulations of motoneurones, which express diverse receptors for neurotrophic factors. Finally, the current status of clinical trials for amyotrophic lateral sclerosis using neurotrophic factors will be discussed, as well as recent reports that neurotrophic factors can exert adverse effects on neuronal survival.

Induction of B cell apoptosis by co-cross-linking CD23 and sIg involves aberrant regulation of c-myc and is inhibited by bcl-2

A novel system to study the effects of co-cross-linking CD23/FceRII and sIg on murine B lymphocytes utilizes a highly multivalent form of anti-Ig prepared by covalently linking anti-Ig antibodies to a DNP-dextran backbone. CD23-sIg co-cross-linking is accomplished by the addition of DNP-specific monoclonal IgE. Previous studies demonstrated that co-cross-linking CD23 and sIg significantly inhibited mouse B cell proliferation, especially at high doses of the multivalent anti-Ig. Interestingly, examination of early activation signals reveals no difference in B cells subjected to co-cross-linking conditions as compared to B cells activated with anti-Ig alone. Total cellular protein tyrosine phosphorylation levels are unchanged by co-cross-linking. Analysis of B cell mRNA reveals that co-cross-linking the receptors does not alter the expression levels of ornithine decarboxylase 8 h after stimulation as compared to the controls. In contrast, levels of the proto-oncogene c-myc were significantly elevated 1 h after inducing B cell activation under co-cross-linking conditions. However, it remains unclear whether this aberrant c-myc regulation plays any role in inducing apoptosis. In addition, on day 3 after stimulation, the co-cross-linking of CD23 and sIg resulted in the formation of apoptotic B cells, determined by both photomicroscopy of the B cell cultures and FACS analysis of B cell nuclei. B cells obtained from bcl-2 transgenic mice proliferated as well as controls, and failed to undergo apoptosis when CD23 and sIg were co-cross-linked on their surface. These studies indicate that co-cross-linking of CD23 with B cell sIg inhibits B cell proliferation by a mechanism that is distinct from that seen by co-cross-linking of the Fc gamma RII and sIg. In addition, these results suggest a means by which antigen-specific IgE can down-regulate additional B cell activation and IgE synthesis.

Rapid development of affinity matured monoclonal antibodies using RIMMS

Affinity matured murine monoclonal antibody producing cell lines can now be rapidly generated using a novel repetitive, multiple site immunization strategy designated RIMMS. RIMMS capitalizes on rapid hypermutation and affinity maturation events which occur in B cell populations localized within secondary lymphatic tissue early in response to antigenic challenges. A murine myeloma cell line, P3XBcl-2-13, stably transfected with Bcl-2, enhances the outgrowth of hybridomas following somatic fusion with immune lymphocytes isolated from pooled peripheral lymph nodes (PLN) 8-14 days after the initial immunization. Immunizations somatic fusion, screening and isolation of affinity matured IgG secreting monoclonal antibody cell lines occur within a one month time period. By using RIMMS, we have been able to expedite the isolation of affinity matured monoclonal antibodies to numerous antigens, including a drug hapten.

[Detection of bcl-2/JH fusion gene in patients with B cell non-Hodgkin's lymphoma by polymerase chain reaction and its clinical implication]

OBJECTIVE

To investigate the frequency and clinical implication of bcl-2/JH gene rearrangement in B cell non-Hodgkin's lymphomas(B-NHLs).

METHODS

Major breakpoint region (MBR) and minor cluster region(mcr) of bcl-2 rearrangement were amplified by polymerase chain reaction in fresh tumor tissue, bone marrow and peripheral blood samples from 23 cases of B-NHL.

RESULTS

Translocation breakpoint was revealed in 10 fresh tumor tissue (71.4% of follicular NHL, 31.3% of diffuse NHL), 8 bone marrow and 7 peripheral blood specimens. The MBR was involved in most of the cases, while the mcr only in one. In addition, of 18 patients with normal bone marrow morphology, 4 were PCR positive, including 2 in early stage ( I and II). Untreated patients with bcl-2 gene rearrangement obtained lower complete remission rate than those without the rearrangement.

CONCLUSION

Detection of bcl-2/JH fusion gene was helpful in diagnosing and staging lymphomas, selecting treatment protocols, and monitoring minimal residual diseases.

Prognostic significance of Bcl-2 expression in localized squamous cell carcinoma of the head and neck

This study was conducted to determine whether Bcl-2 overexpression in localized squamous cell carcinoma of the head and neck (SCCHN) might serve as a marker for tumors unlikely to respond to standard treatment. Tissue samples from 33 patients undergoing surgery or irradiation for early-stage SCCHN during the year 1977 to 1992 were stained for Bcl-2. All patients had either T1N0 lesions of the oral cavity, pharynx, or larynx or T1N0 or T2N0 lesions of the true vocal cords. Of the 33 patients, 26 remained disease-free after at least 3 years of follow-up; the remaining 7 patients developed either tumor recurrence or a second primary tumor, 4 of which were fatal. Twelve patients had tissue specimens staining positive for Bcl-2; 6 of these patients had a poor outcome, and 6 had a good outcome. The relationship between poor outcome and overexpression of Bcl-2 in tumor cells was statistically significant (p = .0047 by Fisher's exact test). For tumors overexpressing Bcl-2, there was no significant difference in recurrence rate between those undergoing surgery and those undergoing radiotherapy as the primary mode of treatment. The overexpression of Bcl-2 in early lesions in this study predicted a cure rate of 50%, as opposed to the generally expected 90%, suggesting that Bcl-2 is a significant prognostic indicator in early SCCHN. Future studies will determine if altering the treatment will improve outcome in these patients.

Prognostic value of the expression of p53, bcl-2, and bax oncoproteins, and neovascularization in patients with radically resected non-small-cell lung cancer

PURPOSE

To assess the prognostic value of p53, bcl-2, bax, and neovascularization in radically resected non-small-cell lung cancer (NSCLC) patients.

PATIENTS AND METHODS

Tumors from 116 patients were assessed by immunohistochemistry for expression of p53 (DO7 and PAb1081), bcl-2, and the quantification of microvessel density (CD-31). In addition, the expression of bax was assessed in 61 stage I tumors. The median levels of expression of each marker were used as cutoff points.

RESULTS

p53 was not correlated to any patient or tumor characteristic, whereas bcl-2 showed higher expression in squamous cell carcinomas (P < .001). bax expression was significantly related with male sex (P = .006) and adenocarcinoma type (P = .0013). p53 status, assessed with one monoclonal antibody (MoAb), was not predictive for survival; however, the combination of staining results obtained with two MoAbs identified the DO7-/PAb1801+ tumors as those with the worst prognosis. bcl-2 expression was associated with longer survival in stage I patients (P = .0169). The combined group expressing p53+(PAb1801)/bcl-2- had the worst survival in stage I patients (P = .034) and in the whole series in comparison with the other combinations of the two oncoproteins. bax expression alone had no influence on survival of stage I patients, but patients with bax+/bcl-2- tumors had the worst prognosis (P = .02 in comparison with bax+/bcl-2+). Tumor neovascularization was not related with other factors, and patients with CD-31+ tumors had a shorter survival duration than those with CD-31- tumors only in stage II (P = .0283). By multivariate analysis including all patients, the presence of p53+/ bcl-2- tumor expression and large tumor diameter (> or = 4cm) were independent prognostic factors for shorter survival duration. For stage I, only the presence of bax+/ bcl-2- tumor expression had a significant negative influence on survival.

CONCLUSION

The interaction and the regulation of new biologic markers, such as those involved in the apoptotic pathway, are complex. Combinations of the expression of several of them may give more valuable information than the study of just one. Prognostic influence of p53 staining varied depending on the choice of antibody and the combination of bcl-2- together with p53+ (PAb1801) or with bax+ had the worst influence on survival for patients with stage I NSCLC.

Multiple bcl-2/Ig gene rearrangements in persistent polyclonal B-cell lymphocytosis

Persistent polyclonal B-cell lymphocytosis is a benign lymphoproliferative disorder of unknown aetiology occurring exclusively in women, characterized by typical binucleated lymphocytes, polyclonal expansion of B cells and elevated serum IgM. Owing to the role of Bcl-2 oncogene in inhibition of apoptosis, we have investigated the presence of the bcl-2/Ig gene rearrangement. Bcl-2/Ig gene rearrangement was determined by polymerase chain reaction targeting the usual breakpoint regions of the t(14;18). Bcl-2/Ig gene rearrangement was identified in all six patients and, more importantly, multiple rearrangements were present in five patients. The frequency of the bcl-2/Ig gene rearrangement is estimated to be of one translocation in 1 x 10(2) to 1 x 10(3) peripheral blood mononuclear cells. We conclude that persistent polyclonal B-cell lymphocytosis is associated with bcl-2/Ig gene rearrangement. These findings are of clinical importance because these patients may be misdiagnosed as having a leukaemic expression of non-Hodgkin's lymphoma.

PCR analysis of IgH and BCL2 gene rearrangement in the diagnosis of follicular lymphoma in lymph node fine-needle aspiration. A critical appraisal

In order to improve the cytomorphologic diagnosis of malignant lymphoma on lymph node fine-needle aspiration (FNA), and to make a confident discrimination between low-grade follicular non-Hodgkin's lymphoma (NHL) and lymphoid hyperplasia, polymerase chain reaction (PCR) analysis was performed of the Ig CDR3 region and BCL2 breakpoint region in 25 nonselected cases of malignant lymphoma (17 NHL and 8 Hodgkin's disease [HD]) with histologic control, and 22 cases of lymph nodal hyperplasia with histologic and/or clinical control. Among lymphomas, IgH monoclonality was detected in 7 (77%) of 9 NHLs and BCL2 rearrangement in 3 (17.6%) of 17 NHLs, all of which were follicular centroblastic-centrocytic (FCBCC). Three BCL2/JH negative FCBCC cases were monoclonal for CDR3. Neither IgH monoclonality nor BCL2 rearrangement were found in HD. Among cytologically diagnosed lymphoid hyperplasias, one IgH polyclonal case was considered false-negative, being histologically diagnosed as lymphoplasmacytic NHL on the subsequent excisional biopsy. Another 4 cases (2 BCL2 rearranged and 2 monoclonal for IgH) were considered false-positive on the basis of histologic features or clinical control. These data indicate that the combined PCR analysis of IgH and BCL2 rearrangements can confirm a cytologic diagnosis of lymphoma in FNAs while, due to the occurrence of both false-positive and false-negative results, it is of limited value in the distinction between follicular lymphoma and lymphoid hyperplasia without morphologic or clinical support.