Tanzanian malignant lymphomas: WHO classification, presentation, ploidy, proliferation and HIV/EBV association

BACKGROUND

In Tanzania, the International Working Formulation [WF] rather than the WHO Classification is still being used in diagnosing malignant lymphomas (ML) and the biological characterization including the HIV/EBV association is sketchy, thus restraining comparison, prognostication and application of established therapeutic protocols.

METHODS

Archival, diagnostic ML biopsies (N = 336), available sera (N = 35) screened by ELISA for HIV antibodies and corresponding clinical/histological reports at Muhimbili National Hospital (MNH) in Tanzania between 1996 and 2006 were retrieved and evaluated. A fraction (N = 174) were analyzed by histopathology and immunohistochemistry (IHC). Selected biopsies were characterized by flow-cytometry (FC) for DNA ploidy (N = 60) and some by in-situ hybridization (ISH) for EBV-encoded RNA (EBER, N = 37).

RESULTS

A third (38.8%, 109/281) of the ML patients with available clinical information had extranodal disease presentation. A total of 158 out of 174 biopsies selected for immunophenotyping were confirmed to be ML which were mostly (84. 8%, 134/158) non-Hodgkin lymphoma (NHL). Most (83.6%, 112/134) of NHL were B-cell lymphomas (BCL) (CD20+), of which 50.9%, (57/112) were diffuse large B-cell (DLBCL). Out of the 158 confirmed MLs, 22 (13.9%) were T-cell [CD3+] lymphomas (TCL) and 24 (15.2%) were Hodgkin lymphomas (HL) [CD30+]. Furthermore, out of the 60 FC analyzed ML cases, 27 (M:F ratio 2:1) were DLBCL, a slight majority (55.6%, 15/27) with activated B-cell like (ABC) and 45% (12/27) with germinal center B-cell like (GCB) immunophenotype. Overall, 40% (24/60) ML were aneuploid mostly (63.0%, 17/27) the DLBCL and TCL (54.5%, 6/11). DNA index (DI) of FC-analyzed ML ranged from 1.103-2.407 (median = 1.51) and most (75.0%) aneuploid cases showed high (>40%) cell proliferation by Ki-67 reactivity. The majority (51.4%, 19/37) of EBER ISH analyzed lymphoma biopsies were positive. Of the serologically tested MLs, 40.0% (14/35) were HIV positive, mostly with high (> or =40.0%) Ki-67 reactivity.

CONCLUSIONS

According to the 2001 WHO Classification, most subtypes are represented in Tanzanian ML. Extranodal presentation was common among MNH lymphoma patients who also showed high aneuploidy, tumor proliferation (KI-67) and EBER positivity. DLBCL was frequent and phenotype heterogeneity appeared similar to observations in Western countries suggesting applicability of established intervention approaches. HIV was apparently associated with high ML cell proliferation but extended studies are needed to clarify this.

Interphase FISH on TEL/AML1 positive acute lymphoblastic leukemia relapses--analysis of clinical relevance of additional TEL and AML1 copy number changes

OBJECTIVES

TEL/AML1 (ETV6/RUNX1) fusion resulting from the translocation t(12;21)(p13;q22) constitutes the most common chimeric fusion gene in initial childhood B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) (19-27%) and has been associated with good prognosis. Three secondary aberrations in TEL/AML1 positive ALL have been suspected to negatively influence outcome: deletion of the second TEL allele (T), gain of the second AML1 allele (A) and duplication of the derivative chromosome 21 (der(21), TA). Many studies have explored such aberrations in initial disease, while only few reports have investigated them in relapses.

METHODS

In this study, bone marrow samples from 38 children with relapsed TEL/AML1 RT-PCR positive and negative BCP-ALL were analyzed for these mutations by interphase fluorescence in situ hybridization and results were compared with published data.

RESULTS

In children with TEL/AML1 positive ALL relapse, additional (a) TEL loss, (b) combined AML1 and der(21) gain, (c) combined TEL loss and AML1 gain as well as (d) the occurrence of a subpopulation with the signal pattern 1T/3A/1TA appear to be related to higher peripheral blast counts (PBCs) at relapse diagnosis (a and d) or a tendency towards the occurrence of a subsequent relapse (b and c) (P-values <0.05).

CONCLUSIONS

Our data together with published results on TEL/AML1 positive ALL suggest that frequencies of additional TEL and AML1 mutations are, with the exception of loss of untranslocated TEL, higher in first relapses than in initial disease. They also show that it is important to consider combined mutations in the analysis of this leukemia entity.

Dose and time dependent apoptotic response in a human melanoma cell line exposed to accelerated boron ions at four different LET

The aim was to investigate and compare the influence of linear energy transfer (LET), dose and time on the induction of apoptosis in a human melanoma cell line exposed to accelerated light boron ((10)B) ions and photons. Cells were exposed in vitro to doses up to 6 Gy accelerated boron ions (40, 80, 125 and 160 eV nm(-1)) and up to 12 Gy photons (0.2 eV nm(-1)). The induction of apoptosis was measured up to 9 days after irradiation using morphological characterization of apoptotic cells and bodies. In parallel, measurements of cell-cycle distribution, monitored by DNA flow cytometry, and cell survival based on the clonogenic cell survival assay, were performed. In addition, the induction and repair of DNA double-strand breaks (DSB), using pulsed-field gel electrophoresis (PFGE) were studied. Accelerated boron ions induced a significant increase in apoptosis as compared with photons at all time points studied. At 1-5 h the percentage of radiation-induced apoptotic cells increased with both dose and LET. At the later time points (24-216 h) the apoptotic response was more complex and did not increase in a strictly LET-dependent manner. The early premitotic apoptotic cells disappeared at 24 h following exposure to the highest LET (160 eV nm(-1)). A postmitotic apoptotic response was seen after release of the dose-, time- and LET-dependent G2/M accumulations. The loss of clonogenic ability was dose- and LET-dependent and the fraction of un-rejoined DSB increased with increasing LET. Despite the LET-dependent clonogenic cell killing, it was not possible to measure quantitatively a LET-dependent apoptotic response. This was due to the different time course of appearance and disappearance of apoptotic cells.

Identification of the human/mouse syntenic common fragile site FRA7K/Fra12C1--relation of FRA7K and other human common fragile sites on chromosome 7 to evolutionary breakpoints

Common fragile sites (CFSs) are expressed as chromosome gaps in cells of different species including human and mouse as a result of the inhibition of DNA replication. They may serve as hot spots for DNA breakage in processes such as tumorigenesis and chromosome evolution. Using multicolor fluorescence in situ hybridization mapping, the authors describe here human CFS FRA7K on chromosome band 7q31.1 and its murine homolog Fra12C1. Within the syntenic FRA7K/Fra12C1 region lies the IMMP2L/Immp2l gene with a size of 899/983 kb. The authors further mapped 2 amplification breakpoints of the breast cancer cell line SKBR3 to the CFSs FRA7G and FRA7H. The 5 molecularly defined CFSs on chromosome 7 do not preferentially colocalize with synteny breaks between the human and mouse genomes and with intragenomic duplications that have occurred during chromosome evolution. In addition, in contrast to all currently reported data, CFSs in chromosome band 7q31 do not show increased DNA helix flexibility in comparison with control regions without CFS expression.

CGH of microdissected Kaposi's sarcoma lesions reveals recurrent loss of chromosome Y in early and additional chromosomal changes in late tumour stages

BACKGROUND

It is still unclear if Kaposi's sarcoma (KS) is a monoclonal cell proliferation or a polyclonal, hyperplastic, reactive process. Reports on KS cytogenetics are few and restricted to late stage disease and cell lines.

METHOD

We analysed 27 KS, early and late, AIDS related (AKS) and endemic (EKS) by laser microdissection, global DNA amplification and comparative genomic hybridization (CGH).

RESULT

Loss of Y chromosome was detected in 20/23 male KS, which was the only recurrent chromosomal aberration in all nine male early (patch) KS. Only one patch EKS showed in addition to the Y loss a loss of Xq. Late (nodular) AKS and EKS showed recurrent copy number changes in chromosomes 16, 17, 21, X and Y, as well as other random changes. The loss of chromosome 16, 17 and Y was confirmed by interphase fluorescence in situ hybridization (FISH) on paraffin sections. EKS showed a higher number of chromosomal abnormalities than AKS, indicating that rapid growth of AKS is less dependent on genetic changes than is EKS, possibly because of the immunosuppressed host environment in AKS.

CONCLUSION

Clonal loss of chromosome Y was detected in all early male KS, while additional chromosomal aberrations appeared during development to late KS. This increase in chromosomal abnormalities during tumour growth indicates genetic instability and the selection of survival cell clones establishing late, aggressive sarcoma growth. Our data support the view that KS (in males) develops into a clonal tumour yet initially is a hyperplastic reactive cell proliferation.

Common fragile sites are conserved features of human and mouse chromosomes and relate to large active genes

Common fragile sites (CFSs) are seen as chromosomal gaps and breaks brought about by inhibition of replication, and it is thought that they cluster with tumor breakpoints. This study presents a comprehensive analysis using conventional and molecular cytogenetic mapping of CFSs and their expression frequencies in two mouse strains, BALB/c and C57BL/6, and in human probands. Here we show that induced mouse CFSs relate to sites of spontaneous gaps and breaks and that CFS expression levels in chromosome bands are conserved between the two mouse strains and between syntenic mouse and human DNA segments. Furthermore, four additional mouse CFSs were found to be homologous to human CFSs on the molecular cytogenetic level (Fra2D-FRA2G, Fra4C2-FRA9E, Fra6A3.1-FRA7G, and Fra6B1-FRA7H), increasing the number of such CFSs already described in the literature to eight. Contrary to previous reports, DNA helix flexibility is not increased in the 15 human and eight mouse CFSs molecularly defined so far, compared to large nonfragile control regions. Our findings suggest that the mechanisms that provoke instability at CFSs are evolutionarily conserved. The role that large transcriptionally active genes may play in CFS expression is discussed.

Lymphatic and vascular origin of Kaposi's sarcoma spindle cells during tumor development

The histogenesis of Kaposi's sarcoma (KS) tumor spindle cells (SC) remains controversial but several immunohistochemical studies favor a lymphatic origin. Twenty KS surgical biopsies were analyzed for the coexpression of LANA, CD34, LYVE-1, D2-40, VEGFR-2, VEGFR3 by using double or triple immunostaining. Most of the SC in both early and late KS expressed the lymphatic markers LYVE-1, D2-40 and VEGFR-3 and the blood vascular endothelial/endothelial precursor cell markers CD34 and endothelial stem cell marker VEGFR-2. All the LANA+ SC in early and late KS were LYVE-1+, but only 75% of these LANA+ cells were CD34(+). The CD34(+)/LANA+ cells increased from early- (68.8%) to late-stage KS (82.2%). However, approximately 18% of the LANA+ SC in early KS were CD34(-) but were LYVE-1+, suggesting that resident lymphatic endothelial cells (LEC) are targeted for primary infection by human herpesvirus-8. This LANA+/LYVE-1+/CD34(-) (resident LEC) cell population clearly decreased during the development of KS from early (18.7%) to late KS (2.9%). Thus, in late stages of KS, most SC were LANA+/CD34(+)/LYVE-1+. However, in both early- and late-stage KS, approximately 18% of the SC were CD34(+)/LANA-/LYVE-1 -- and could represent newly recruited endothelial precursor cells, which become infected in the lesion and eventually undergo a phenotype switch expressing LEC markers. Our study apparently indicates that KS represents a unique variant of tumor growth with continues recruitment of tumor precursor cells as well as proliferation and decreased apoptosis of SC.

Human herpesvirus 8/Kaposi sarcoma herpesvirus cell association during evolution of Kaposi sarcoma

Kaposi sarcoma (KS) is associated with a herpesvirus (HHV-8/KSHV), which expresses a latency-associated nuclear antigen (LANA). The histopathology of KS is characterized by angiogenesis, inflammatory cells, and the development of CD34+ tumor spindle cells (SCs). However, the cellular basis for the recruitment and dissemination of HHV-8 during the development of KS lesions is not clear. Twenty-nine KS biopsies with AIDS (AKS, n=22) and without HIV infection (endemic KS or EKS, n=7) were immunostained by a triple antibody method to characterize HHV-8-infected and noninfected (LANA+/-) CD34+ SCs, infiltrating CD3+, CD68+, CD20+, and CD45+ leukocytes as well as proliferating (Ki67+) cells. The CD34+/LANA+ SCs were more frequent in late (nodular) as compared with early (patch/plaque) KS stages. However, in late AKS 36.0% of SCs (median of 11 cases) were CD34+/LANA- compared with 20.7% in early cases (median of 11 cases). Furthermore, both AKS and EKS showed, at all stages, a small (4.1-6.5%) population of LANA+/CD34- cells. Proliferating Ki67+ cells were seen (4.5-11.5%) at all KS stages, and were usually more frequent in early AKS, but no significant difference was observed between nodular AKS and EKS. Most of the proliferating cells in the KS lesions were LANA+/CD34+ but a small fraction was LANA+/CD34-. Lesional CD68+ and CD3+ cells varied between AKS (7.3 and 5.2%, respectively) and EKS (4.9 and 3.1%, respectively) but were not clearly stage related. No LANA+ cells were CD3+, CD20+, or CD45+ and very few (<0.5%) were CD68+. These results indicate that not all CD34+ KS SCs were LANA+, suggesting recruitment of noninfected SCs to the lesions. Cell proliferation in general was much higher in early as compared with the late AKS stages. LANA+ SCs could have a proliferative advantage as suggested by higher frequency of cycling (Ki67+) LANA+ SCs. Few macrophages but no lymphocytes are LANA+.

Different G2/M accumulation in M059J and M059K cells after exposure to DNA double-strand break-inducing agents

PURPOSE

To investigate and compare the cell cycle progression in relation to cell death in the human glioma cell lines, M059J and M059K, after exposure to DNA double-strand break-inducing agents.

METHODS AND MATERIALS

The M059J and M059K cells, deficient and proficient in the catalytic subunit of the DNA-dependent protein kinase, respectively, were exposed to 1 and 4 Gy of photons or accelerated nitrogen ions. In addition, M059J and M059K cells were treated with 10 and 40 mug/mL of bleomycin for 30 min, respectively. Cell cycle progression, monitored by DNA flow cytometry, was measured up to 72 h after treatment.

RESULTS

M059J, but not M059K, cells displayed G(2)/M accumulation after low linear energy transfer irradiation. High linear energy transfer radiation exposure however, resulted in a substantial increase of M059K cells in the G(2)/M phase detected at 48 h. At 72 h, the number of cells in the G(2)/M phase was equivalent to its control. M059J cells accumulated mainly in S phase after high linear energy transfer irradiation. In contrast to M059K, M059J cells were still blocked at 72 h. Bleomycin induced G(2)/M accumulation for both M059J and M059K cells detected 24 h after treatment. At 48 h, the percentage of bleomycin-treated M059J cells in G(2)/M phase remained high, and the number of M059K cells had decreased to control levels. Neither cell line showed cell cycle arrest (< or =10 h) after exposure to these agents.

CONCLUSION

Distinct cell cycle block and release is dependent on the complexity of the induced DNA damage and the presence of the DNA-dependent protein kinase catalytic subunit.

Epstein-Barr virus LMP1 status in relation to apoptosis, p53 expression and leucocyte infiltration in nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal carcinoma (NPC) is consistently associated with Epstein-Barr virus (EBV) infection. EBV-encoded LMP1, expressed in most of NPC, has been suggested to have an important role in the pathogenesis and development of NPC and its expression correlates with poor prognosis.

MATERIALS AND METHODS

Eighty-seven NPC biopsies were analyzed by immunohistochemistry for expression of markers of cell proliferation, apoptosis, infiltrating T lymphocytes and macrophages in relation to the LMP1 status.

RESULTS

Our findings indicate that the p53 accumulation in NPC was significantly correlated to LMP1 and MMP9 overexpression in NPC cells. The frequency of apoptotic cells in NPC, as analyzed by TUNEL labeling, correlated to Fas-L and caspase-3 expression, and inversely to LMP1, p53 and MMP 9 expression. CD8+ T cell infiltration was predominately seen in nests of cancer cells with a high level of EBV-LMP1 expression, but these CD8+ T cells showed low expression of CD25 and TIA-1, indicating that they were not activated.

CONCLUSION

Our observation suggests that the heavy infiltration by lymphocytes in LMP1-positive NPC tumors does not appear to counteract tumor growth by cytoxicity as indicated by the low apoptotic index. Thus, LMP1 seems to enhance survival- and proliferation-related signals in NPC. In analogy with other tumors, both the infiltrating T cells and the accumulated p53 may be inactive.

Aged transgenic mice with increased glucocorticoid sensitivity in pancreatic beta-cells develop diabetes

Glucocorticoids are diabetogenic hormones because they decrease glucose uptake, increase hepatic glucose production, and inhibit insulin release. To study the long-term effects of increased glucocorticoid sensitivity in beta-cells, we studied transgenic mice overexpressing the rat glucocorticoid receptor targeted to the beta-cells using the rat insulin I promoter. Here we report that these mice developed hyperglycemia both in the fed and the overnight-fasted states at 12-15 months of age. Progression from impaired glucose tolerance, previously observed in the same colony at the age of 3 months, to manifest diabetes was not associated with morphological changes or increased apoptosis in the beta-cells. Instead, our current results suggest that the development of diabetes is due to augmented inhibition of insulin secretion through alpha(2)-adrenergic receptors (alpha(2)-ARs). Thus, we found a significantly higher density of alpha(2)-ARs in the islets of transgenic mice compared with controls, based on binding studies with the alpha(2)-AR agonist UK 14304. Furthermore, incubation of islets with benextramine, a selective antagonist of the alpha(2)-AR, restored insulin secretion in response to glucose in isolated islets from transgenic mice, whereas it had no effect on control islets. These results indicate that the chronic enhancement of glucocorticoid signaling in pancreatic beta-cells results in hyperglycemia and impaired glucose tolerance. This effect may involve signaling pathways that participate in the regulation of insulin secretion via the alpha(2)-AR.

Dichotomy between CD1a+ and CD83+ dendritic cells in lymph nodes during SIV infection of macaques

The prevalence and differentiation of dendritic cells (DC) in lymphoid tissue of simian immunodeficiency virus (SIV)-infected cynomolgus monkeys was studied during disease progression. Lymph node biopsies were consecutively obtained from clinical rapid and slow progressors until the development of disease consistent with simian acquired immunodeficiency syndrome (sAIDS) occurred. Quantitative evaluation of CD1a+ DC and the expression of DC antigens related to maturation (CD83, DC-LAMP and S100b) were performed at the single cell level by in situ image analysis. Despite a persistent prevalence of CD1a+ DC in lymphoid tissue during disease progression, there was a subsequent drop of mature CD83+, DC-LAMP+ and S100b+ DC, correlating with the decline of CD4+ T cells in blood. Thus, disease progression to sAIDS was associated with impaired maturation of DC, and lack of CD83, DC-LAMP and S100b expression.

Serum HHV8 DNA and Tat antibodies in Kaposi's sarcoma patients with and without HIV-1 infection

Human herpesvirus 8 or Kaposi's sarcoma-associated herpesvirus (HHV8/KSHV) is believed to be the most important etiopathological factor of Kaposi's sarcoma (KS) and some specific types of malignant lymphomas. The diagnostic and prognostic significance of serum viral load in endemic (African) areas is poorly understood. In AIDS-related KS (AKS) it has been shown that HIV-Tat may be of pathogenic importance and that immunoreactivity to Tat may have prognostic significance. Here we report on the quantitative analysis of HHV8 DNA in serum from Tanzanian patients with KS (n = 19), either AIDS-related (AKS) (n = 14) or endemic KS (EKS) (n = 5) and non-KS control individuals (n = 4). Fourteen AKS sera were also tested for HIV-tat antibodies by a direct ELISA assay. In AKS patients detectable (12 out of 14) serum HHV8 DNA levels showed a median of 1400 copies/ml as compared to a median of 200 copies/ml for EKS, but for one AKS case with an exceptionally high level (25,500 copies/ml). The serum HHV8 DNA levels were usually higher in males (n = 17; median 580 DNA copies/ml) as compared to females (n = 6; median 120 DNA copies/ml) and in early, patch stages (n = 8; median 2,750 copies/ml) as compared to late, nodular stages (n = 11; median 200 DNA copies/ml). Of fourteen sera from AKS patients, seven were positive for antibody against HIV-1 tat. Epitope analysis of the anti-tat antibody spectrum showed reactivity to various non-functional sites, but not towards the functional epitopes 46-60 (TAR-binding region).

Noninvasive estimation of tumour viability in a xenograft model of human neuroblastoma with proton magnetic resonance spectroscopy (1H MRS)

The aim of the study was to evaluate proton magnetic resonance spectroscopy ((1)H MRS) for noninvasive biological characterisation of neuroblastoma xenografts in vivo. For designing the experiments, human neuroblastoma xenografts growing subcutaneously in nude rats were analysed in vivo with (1)H MRS and magnetic resonance imaging at 4.7 T. The effects of spontaneous tumour growth and antiangiogenesis treatment, respectively, on spectral characteristics were evaluated. The spectroscopic findings were compared to tumour morphology, proliferation and viable tumour tissue fraction. The results showed that signals from choline (Cho)-containing compounds and mobile lipids (MLs) dominated the spectra. The individual ML/Cho ratios for both treated and untreated tumours were positively correlated with tumour volume (P<0.05). There was an inverse correlation between the ML/Cho ratio and the viable tumour fraction (r=-0.86, P<0.001). Higher ML/Cho ratios concomitant with pronounced histological changes were seen in spectra from tumours treated with the antiangiogenic drug TNP-470, compared to untreated control tumours (P<0.05). In conclusion, the ML/Cho ratio obtained in vivo by (1)H MRS enabled accurate assessment of the viable tumour fraction in a human neuroblastoma xenograft model. (1)H MRS also revealed early metabolic effects of antiangiogenesis treatment. (1)H MRS could prove useful as a tool to monitor experimental therapy in preclinical models of neuroblastoma, and possibly also in children.

Cross-talk between human herpesvirus 8 and the transactivator protein in the pathogenesis of Kaposi's sarcoma in HIV-infected patients

AIDS-associated Kaposi's sarcoma (AKS) is particularly aggressive and it is one of the principal neoplasms in regions of Africa affected by both high endemic HHV8 and epidemic HIV infection. In this study, serum samples from 18 patients with Kaposi's sarcoma from Tanzania, mostly males (n = 15 vs 3), were subjected to analysis with respect to HHV8-DNA load and antibody spectrum against the HIV-1 tat protein. Of the 18 patients, 14 were HIV-1-positive. The median HHV8 virus load in the HIV-1-positive group was 2075 DNA copies/ml, compared to 450 copies/ml in the HIV-1-negative group. In the HIV-1-positive group, the males had a higher HHV8-DNA virus load as compared to females (median: 4600 vs 1400 genome copies per ml). Since tat can promote AKS development (4-6) by intercellular signalling pathways, and these signals can be abolished by anti-tat IgG (7-9), we have examined the anti-tat IgG spectrum in this study. It would be expected that the levels of serum HHV8-DNA are higher in KS patients who have low anti-tat IgG titer, or who are anti-tat IgG-negative. In the present study, seven out of fifteen AKS patients were positive for anti-tat IgG. Although, we have not seen a strict quantitative relationship between serum anti-tat IgG and HHV8-DNA levels, our data appear to suggest a correlation between the two parameters. In view of these observations and the published data, we suggest that cross-signalling pathways between the tat protein and HHV8-DNA are involved in the complexity of pathogenesis of Kaposi's sarcoma.

Calpain-mediated Bid cleavage and calpain-independent Bak modulation: two separate pathways in cisplatin-induced apoptosis

Calpain is a ubiquitous protease with potential involvement in apoptosis. We report that in human melanoma cells, cisplatin-induced calpain activation occurs early in apoptosis. Calpain activation and subsequent apoptosis were inhibited by calpeptin and PD150606, two calpain inhibitors with different modes of action. Furthermore, cisplatin induced cleavage of the BH3-only protein Bid, yielding a 14-kDa fragment similar to proapoptotic, caspase-cleaved Bid. However, Bid cleavage was inhibited by inhibitors of calpain, but not by inhibitors of caspases or of cathepsin L. Recombinant Bid was cleaved in vitro by both recombinant calpain and by lysates of cisplatin-treated cells. Cleavage was calpeptin sensitive, and the cleavage site was mapped between Gly70 and Arg71. Calpain-cleaved Bid induced cytochrome c release from isolated mitochondria. While calpeptin did not affect cisplatin-induced modulation of Bak to its proapoptotic conformation, a dominant-negative mutant of MEKK1 (dnMEKK) inhibited Bak modulation. dnMEKK did not, however, block Bid cleavage. The combination of dnMEKK and calpeptin had an additive inhibitory effect on apoptosis. In summary, calpain-mediated Bid cleavage is important in drug-induced apoptosis, and cisplatin induces at least two separate apoptotic signaling pathways resulting in Bid cleavage and Bak modulation, respectively.

Simian AIDS-related lymphoma growth in severe combined immunodeficiency mice is independent of karyotypic abnormalities or Bcl-6 mutations

Simian AIDS-related lymphomas (sARL) of cynomolgus monkeys infected with a simian immunodeficiency virus (SIVsm) were studied in relation to growth in severe combined immunodeficient (SCID) mice, karyotype abnormalities, and DNA sequence of the first noncoding region of the Bcl-6 gene. The tumors were diffuse large B cell lymphomas and expressed a simian homolog to Epstein-Barr virus (HVMF-1) in 12 of 13 primary tumors and corresponding cell lines. A tested cell line was tumorigenic in SCID mice. Tumors in the SCID mice showed cell growth features similar to those in the original lymphoma, suggesting that no subpopulation with growth advantage was selected for in the mice. Spectral karyotype analysis of sARL cell lines showed normal cytogenetic features except for a trisomy of monkey chromosome 2 (corresponding to human chromosomes 7 and 21) in two of five sARL lines, which was not recovered in SCID tumors established from the same cell line. Sequence analysis of a Bcl-6 gene fragment showed sequence variations indicative of population polymorphism(s) in 10 of 13 sARLs, and no evidence of Bcl-6 mutations. Thus Bcl-6 mutations in the first noncoding region are irrelevant for sARL development in cynomolgus monkeys and for tumorigenicity of sARL cell lines. We also demonstrate that no cytogenetic alterations are needed for the development of highly aggressive lymphomas in the SIV-immunosuppressed host.

Diagnostic DNA-flow- vs. -image-cytometry in effusion cytology

AIMS

To determine the sensitivity and specificity of flow- and image-cytometry for the detection of DNA-aneuploidy as a marker for malignant cells in effusions.

METHODS

200 effusions (80 tumor cell-positive, 74 negative and 46 cytologically equivocal) were stained with DAPI-SR for DNA-flow- and with Feulgen-Pararosaniline for -image-cytometry. They were measured using a PAS-flow-cytometer and an AutoCyte-QUIC-DNA-workstation according to the ESACP consensus reports for DNA-flow- and -image-cytometry, respectively [7,23,29,49].

RESULTS

Sensitivity of DNA-aneuploidy for the identification of malignant cells was 32.1% for DNA-flow- and 75.0% for -image-cytometry, specificity of -euploidy in benign cells was 100.0% for both methods. Positive predictive value of DNA-aneuploidy for the identification of malignant cells was 100.0% for both techniques, negative predictive value of DNA-euploidy was 48.6% for DNA-flow- and 72.0% for -image-cytometry.

CONCLUSIONS

Searching for DNA-aneuploidy as a diagnostic marker for neoplastic cells in serous effusions image-cytometry revealed superior sensitivity as compared with monoparametric flow cytometry.

Expression of CTLA-4 by human monocytes

Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4) is a receptor present on T cells that plays a critical role in the downregulation of antigen-activated immune responses. CTLA-4 interacts with the ligands CD80 and CD86 on antigen-presenting cells (APC), and also directs the assembly of inhibitory signalling complexes that lead to quiescence or anergy. In this study, we show that human monocytes constitutively express CTLA-4. About 3% of monocytes expressed CTLA-4 on the cell surface, whereas the intracellular expression was higher and present in about 20% of the monocytes. The sequences of the cDNAs from human monocytes were identical to the sequences of CTLA-4 from T cells. Expression of CTLA-4 was also confirmed in the activated myelomonocytic cell lines U937 and THP-1. Monocytes, but not T cells, activated by interferon (IFN)-gamma also secreted soluble CTLA-4 in vitro. The CTLA-4 expression was upregulated upon treatment with phorbol 12-myristate 13-acetate (PMA) and IFN-gamma. This increased expression could be partially abolished by staurosporine, an inhibitor of protein kinase C (PKC). Ligation of CTLA-4 in the monocyte-like cell-line U937 with antibodies against CTLA-4 partially inhibited the proliferation of cells and the upregulation of cell-surface markers CD86, CD54, HLA-DR and HLA-DQ induced by IFN-gamma and Staphylococcus aureus, Cowan I strain (SAC). Ligation of CTLA-4 suppressed the PMA-stimulated activation of transcription activator protein 1 (AP-1) and nuclear factor (NF)-kappaB in the U937 cell line, indicating the involvement of an inhibitory signal transduction. These data provide the first evidence that CTLA-4 is constitutively expressed by monocytes and thus might be important for the regulation of immune mechanisms associated with monocytes.

The MEK1 inhibitor PD98059 sensitizes C8161 melanoma cells to cisplatin-induced apoptosis

The regulation of apoptosis is believed to be dependent on the balance of the activities of different intracellular signalling systems. Activation of the SAPK/JNK pathway is implied in pro-apoptotic signalling, while activation of the MEK1/ERK pathway may have a viability-promoting effect. We show here that treatment with the MEK1 inhibitor PD98059 sensitizes the human melanoma cell line C8161 to cisplatin-induced apoptosis. In these cells, cisplatin at 40 microM did not elicit significant cell death, whereas massive cell death was seen when cells were pretreated for 20 h with 40 microM PD98059 before the addition of cisplatin. Concomitant addition of PD98059 and cisplatin did not have any sensitizing effect, and PD98059 on its own did not induce apoptosis. However, in three other human melanoma cell lines PD98059 did not potentiate cisplatin-induced apoptosis. Instead, in one of these cell lines (AA), PD98059 protected against cisplatin-induced cytotoxicity. We conclude that blocking of the MEK1/ERK pathway may, in some instances, potentiate the cytotoxic effect of cisplatin on human melanoma cell lines, whereas in other instances it may have a protective effect. Thus it cannot be regarded as a general approach to sensitizing melanoma cells to drug-induced apoptosis.

Proliferation and apoptosis in the evolution of endemic and acquired immunodeficiency syndrome-related Kaposi's sarcoma

Kaposi's sarcoma (KS) is a multifocal lesion that occurs predominantly in the skin, most frequently in people infected with HIV-1, and that evolves through early stages (patch and plaque) to a tumor-like late stage (nodular). Both, endemic African (EKS) and AIDS-associated (AKS) KS expressed human herpesvirus 8 (HHV-8) as shown by PCR. By immunohistochemistry the expression of cellular Bcl-2 and c-myc was confined in early stages of both EKS and AKS to relatively few endothelial cells (EC) whereas in nodular KS most of spindle cells (SC) strongly expressed both genes. CD40 was usually strongly expressed in SC at all KS stages as well as in EC of non-involved tissue whereas CD40L (CD154) was not demonstrable. Fas (CD95) was moderately to weakly expressed by SC whereas p53 and Waf-1 were found in less than 5% of the SC. In both AKS and EKS at nodular stage almost no apoptotic SC were detected. In most AKS and EKS low levels of cell proliferation were seen but AKS showed consistently higher values compared to EKS. All clinical types and stages of KS showed a diploid cellular DNA content by flow cytometric analysis of microselected lesions. Thus, we conclude that KS during evolution represents diploid, probably reactive, cell proliferation, which progressively increases the expression of strong cellular and also viral (HHV-8) antiapoptotic factors.

Increased apoptosis and increased clonogenic survival of 12V-H-ras transformed rat fibroblasts in response to cisplatin

Mutationally activated Ras is involved in tumor progression and likely also in drug resistance. Using survival, viability and apoptosis assays, we have here compared the cisplatin sensitivities of FR3T3 rat fibroblasts and a 12V-H-ras transformed subline (Ras2:3). Around 24 h after cisplatin treatment Ras2:3 cells showed higher apoptosis levels and lower viability than FR3T3. This increased sensitivity correlated with weaker cisplatin-induced activation of Jun N-terminal kinase (JNK). In contrast to apoptosis assays, colony formation assays showed that Ras2:3 were more resistant to cisplatin than were FR3T3. This was partly due to the increased cisplatin sensitivity of FR3T3 seeded at low densities, as required in colony formation assays. In addition, Ras2:3 cisplatin survivors had a higher relative proliferative capacity. Cell cycle analyses showed that FR3T3 cells initially responded with a dose-dependent G2 arrest, while Ras2:3 accumulated in S-phase. Experiments with an anti-apoptotic mutant of MEKK1 suggested that the apoptotic response of Ras2:3 cells is not specific to the S-phase fraction. In summary, the cisplatin response of ras-transformed fibroblasts is distinct from that of parental cells, in that they show increased apoptosis, a different cell cycle response and increased post-treatment proliferative capacity. The results illustrate the need to carefully consider methods and protocols for in vitro studies on chemotherapy sensitivity.

Combined analysis of DNA ploidy, proliferation, and apoptosis in paraffin-embedded cell material by flow cytometry

A flow cytometric assay was developed for correlated measurement of DNA content and apoptotic DNA strand breaks in cell nuclei of formalin-fixed, paraffin-embedded tissues. The assay allows a combined analysis of cell ploidy, proliferation, and apoptosis in sections of fixed paraffin-embedded archival or fresh tissue/cell specimens. It is based on (a) proteolytic release of cell nuclei from deparaffinized and rehydrated 90-microm thick sections of the fixed embedded specimen, (b) the inactivation of the protease, (c) FITC-labeling of DNA strand breaks by the terminal deoxynucleotidyl transferase (TdT)-mediated FITC-dUTP nick end-labeling (TUNEL) reaction, and (d) DNA staining with 4'6-diamidino-2-phenyleindole. The fluorescence was recorded with a double-beam flow cytometer equipped with a mercury arc lamp and an argon ion laser. Cytograms obtained with this assay correlated closely with those produced using nonembedded material from the same specimen. Furthermore, a significant correlation was found between flow cytometric analysis of apoptosis in cell nuclei released from paraffin blocks and conventional evaluation of TUNEL on (corresponding) sections (p < 0.001). Since necrotic cells can stain positively by TUNEL, the possibility to microscopically select nonnecrotic tumor regions for flow cytometric analysis is an important advantage of the assay.

Reliability of DNA cytometric S-phase analysis in surgical biopsies: assessment of systematic and sampling errors and comparison between results obtained by image and flow cytometry

Three major parameters in DNA histograms that contribute to the reliability of S-phase analysis were evaluated. These parameters are (1) the extent of background in relation to the amount of S-phase cells (and the validity of its subtraction), (2) the size of the "free" S-phase range (S(free)), and (3) the sampling error of cell counting. Tests in histograms obtained from surgical biopsies by flow cytometry (FCM) showed that the background subtraction is reliable if the found S-phase fraction is higher than the fraction of background events in the histogram range of the cell population. The size of S(free) was determined in computer-generated test histograms as a function of variables such as the coefficient of variation (CV) and the DNA index (DI). To calculate the sampling error of cell counting above background and in S(free), a model was developed that was validated by experimental data. This error can serve as an indicator of the uncertainty in S-phase analysis. The poor correlation found between %S values measured by image cytometry (ICM) and FCM in surgical biopsies was assigned to high uncertainty by low cell numbers in ICM histograms. A method is proposed to estimate quantitatively the reliability of S-phase analysis that can facilitate the interpretation of results.

Molecular mechanisms underlying interferon-alpha-induced G0/G1 arrest: CKI-mediated regulation of G1 Cdk-complexes and activation of pocket proteins

One prominent effect of IFNs is their cell growth-inhibitory activity. The mechanism behind this inhibition of proliferation is still not fully understood. In this study, the effect of IFN-alpha treatment on cell cycle progression has been analysed in three lymphoid cell lines, Daudi, U-266 and H9. Examination of the growth-arrested cell populations shows that Daudi cells accumulate in a G0-like state, whereas U-266 cells arrest later in G1. H9 cells are completely resistant to IFN-alpha's cell growth-inhibitory effects. The G0/G1-phase arrest is preceded by a rapid induction of the cyclin-dependent kinase inhibitors (CKIs), p21 and p15. In parallel, the activities of the G1 Cdks are significantly reduced. In addition to p21/p15 induction, IFN-alpha regulates the expression of another CKI, p27, presumably by a post-transcriptional mechanism. In the G1 Cdk-complexes, there is first an increased binding of p21 and p15 to their respective kinases. At longer exposure times, when Cdk-bound p15 and p21 decline, p27 starts to accumulate. Furthermore, we found that IFN-alpha not only suppresses the phosphorylation of pRb, but also alters the phosphorylation and expression of the other pocket proteins p130 and p107. These data suggest that induction of p21/p15 is involved in the primary IFN-alpha response inhibiting G1 Cdk activity, whereas increased p27 expression is part of a second set of events which keep these Cdks in their inactive form. Moreover, elevated levels of p27 correlated with a dissociation of cyclin E/Cdk2-p130 or p107 complexes to yield cyclin E/Cdk2-p27 complexes. In resistant H9 cells, which possess a homozygous deletion of the p15/p16 genes and lack p21 protein expression, IFN-alpha causes no detectable changes in p27 expression and, furthermore, no effects are observed on either pocket proteins in this cell line. Taken together, these data suggest that the early decline in G1 Cdk activity, subsequent changes in phosphorylation of pocket proteins, and G1/G0 arrest following IFN-alpha treatment, is not primarily due to loss of the G1 kinase components, but result from the inhibitory action of CKIs on these complexes.

Proliferation and apoptosis-related gene expression in experimental acquired immunodeficiency syndrome-related simian lymphoma

Lymphomas in 10 cynomolgus monkeys infected with a simian immunodeficiency virus (SIVsm) were studied with regard to proliferative activity and apoptosis-related gene expression. All were diffuse large-cell lymphomas, showed mono or oligoclonality and a 9/10 diploid cellular DNA content. Expression of a simian homologue to Epstein-Barr virus (HVMF-1) was shown in nine cases. The lymphomas showed moderate to high proliferative activity by Ki67 immunostaining and DNA flow cytometry, and a low number of apoptotic cells detected by TdT-mediated dUTP nick-end labeling (TUNEL). Immunohistochemistry showed abundant tumor infiltrating TIA-1(+) cytotoxic lymphocytes (CTL) and macrophages. Bcl-2, Mcl-1, and also Bax and Bak, but not p53 were demonstrable in the tumor cells by immunostaining. Our findings suggest a causal relationship between HVMF-1 infection and a low apoptotic index of the lymphomas due to the expression of Bcl-2. The apparent inefficient function of tumor-infiltrating CTL could be due to inactivation of CTL and/or resistance of the lymphoma cells to CTL effects. The tumors showed immunoreactivity for CD18, CD29, and CD49d, but not for CD11a, mimicking the phenotype of human Epstein-Barr virus (EBV)-related lymphomas. In summary, our observations indicate a high similarity between this simian model of acquired immunodeficiency syndrome (AIDS)-related lymphomas (ARL) and human ARL and other immunosuppression-related lymphomas.

Comparison of routine flow cytometric DNA analysis of fresh tissues in two laboratories: effects of differences in preparation methods and background models of cell cycle calculation

Routine flow cytometric DNA analysis was compared in two laboratories by using matched fresh-frozen breast cancer and soft tissue sarcoma biopsy specimens. Laboratory I applied the Vindelöv preparation method and an exponential background subtraction algorithm in the cell cycle calculation. Laboratory II used the Formalin-protease preparation technique and the sliced-nuclei background model. The results of the ploidy analysis showed good agreement between the two laboratories; however, the results of the cell cycle analysis showed considerable systematic differences between labs. Laboratory I obtained significantly lower values of S-phase fraction and higher values of G2-phase fraction than laboratory II. To explain these discrepancies, the effects of differences in the preparation methods and background subtraction algorithms were studied. The Vindelöv preparation method yielded higher debris and aggregation levels than the Formalin-protease technique and tended to give higher %S and %G2 values. When the two background models were used in the same histograms, the exponential background model tended to give %S values distinctly lower than and %G2 values almost identical to those obtained with the sliced-nuclei algorithm. The sum of these effects accounts for the observed inter-laboratory discrepancies. Different from the sliced-nuclei fit, the exponential background fit often did not accommodate to the original data in the <2c histogram region and resulted in a considerable inter-operator variability of %S calculation in histograms with <5% S. When aggregate correction was added to the sliced-nuclei algorithm, the differences between %S values in histograms from the two laboratories almost disappeared.

Comparison between radiation-induced cell cycle delay in lymphocytes and radiotherapy response in head and neck cancer

A study was made evaluating the use of radiation-induced cell cycle delay in lymphocytes to predict tumour response to radiotherapy. Peripheral blood lymphocytes were isolated from whole blood from 49 patients with head and neck cancer before treatment with radiotherapy and from 25 healthy donors. The clinical response to radiotherapy was assessed at 0-2 months after treatment. The level of radiation-induced cell cycle delay was measured using flow cytometry after mitogen stimulation of lymphocytes. The analysis of ten normal donors gave no significant difference in variability between the intra-assay and the intra-donor samples. However, the cell cycle data for lymphocytes from these healthy donors showed significant inter-individual differences in G2 phase accumulation. Patients showing no response to radiotherapy had a high level of S-phase cells compared with partial (P < 0.001) and complete responders (P = 0.016). An inverse relationship was found when analysing the fraction of cells in G2 (P = 0.009 and 0.034 respectively). In general, healthy donors had similar cell cycle kinetics compared with the non-responders. In conclusion, the result indicates that radiation-induced cell cycle delay in lymphocytes is inversely correlated with tumour response to radiotherapy in head and neck cancer patients. However, the value of the present test for predicting individual tumour response is limited, because of assay variability and overlap between groups.

Characterisation of the G1/S cell cycle checkpoint defect in lung carcinoma cells with different intrinsic radiosensitivities

Cell cycle perturbations in three lung carcinoma cell lines (U-1285,U1906 and U-1810) with different intrinsic radiosensitivities (SF2 U-1285 = 0.25, SF2 U-1906 = 0.45, SF2 U-1810 = 0.88) were investigated following x-irradiation. Cell cycle flow calculations showed that the G1-->S-phase transit was accelerated in irradiated compared with untreated U-1285 cells, up to 24 hours postirradiation. In U-1810 cells and U-1906 cells the postirradiation G1-->S transit decreased compared with controls. All three cell lines showed no postirradiation induction of p53 and p21CIP1 proteins. Cyclin E was overexpressed and cyclin E-dependent kinase activity was substantially induced by irradiation in U-1285 cells compared with U-1906 and U1810 cells while p27KIP1 was detected at the highest intensity in U-1810 cells and lowest in U-1285 cells. We hypothesise that the accelerated postirradiation G1-->S transit in U-1285 cells is associated with induction of cyclin E-dependent kinase activity and may account for increased radiosensitivity in these cells.

Induction of apoptosis and inhibition of cell growth are independent responses to interferon-alpha in hematopoietic cell lines

IFNs are capable of modulating a variety of cellular responses, including cell growth and apoptosis. The prospective connections between these two biological responses are not fully understood, and the molecular mechanisms underlying the effects of IFNs on these processes are not completely defined. We have investigated the relationship between IFN-alpha-induced apoptosis and cell cycle arrest in three hematopoietic cell lines, Daudi, U-266, and H9. It was found that IFN-alpha was a rapid and potent inducer of apoptosis in H9 and U-266 cells, whereas IFN-alpha-induced cell cycle arrest in Daudi cells is not associated with the onset of apoptosis. In H9 cells, apoptosis occurs without a preceding cell cycle block, whereas in U-266 cells, apoptosis occurs subsequent to G1 arrest. Cell cycle arrest per se, induced by serum starvation or treatment with aphidicolin, had only minor effects on the viability of these cell lines and did not abrogate the apoptosis-inducing capacity of IFN-alpha. Additionally, IFN-alpha-induced apoptosis occurred in cells from all cell cycle phases. Thus, we conclude that IFN-alpha-induced apoptosis seems to occur independent of cell growth inhibition. There were no changes in Bcl-2 or Bax protein levels that could account for the apoptosis-inducing effects of IFN-alpha in these cell lines. Moreover, examination of p53 status suggests that IFN-alpha-induced apoptosis in the U-266 and H9 cell lines occurs through a p53-independent pathway.

Non-tumorigenic SV40T immortalized human buccal epithelial cells show aneuploidy and genetic instability

Cytogenetic and DNA flow cytometric analysis was carried out on four SV40T-transfected human buccal epithelial cells lines. One of these was immortalized and showed a nontumorigenic phenotype when tested in athymic nude mice. DNA flow cytometric ploidy values correlated well with cytogenetic ploidy values as calculated from chromosome length or DNA content, whereas the chromosome counts correlated poorly with the flow cytometric results. Gross ploidy changes were seen at early passages, while the immortalized cell line had a stabilized DNA content in the near diploid range. However, this cell line showed ongoing random chromosomal changes with the appearance of new marker chromosomes balancing chromosome losses. The chromosome losses were mainly found in the groups 12-16 and 18-23 and the gains in the group 1-6. This reflects, together with the stabilization of the DNA content, a nonrandom component in the overall random chromosomal changes. In conclusion, aneuploidy and genetic instability found in the immortalized cell line were not linked to malignant growth in nude mice.

Fluorescence image cytometry for measurement of nuclear DNA content in surgical pathology

A study was made on various methodological aspects of fluorescence image cytometry (FICM) for measurement of nuclear DNA content by using CCD cameras attached to an epifluorescence microscope. Cell nuclei of paraffin-embedded specimens from mouse tissues and human prostate carcinomas were isolated and stained with 4'-6-diamidino-2-phenylindole (DAPI). We found that fluorescence fading, lamp stability, and the homogeneity of the illumination can easily be controlled. A camera with a signal-to-noise ratio of 53 dB gave a slightly more precise measurement than did a 46-dB camera. The linearity of the analysis results was very good. The coefficient of variation of mouse kidney standard cells in the DNA histograms was about 5% and 7.4% in histograms of prostate carcinoma biopsies. Stained cell nuclei can be stored for long periods at -20 degrees C without impairment of quality. Comparative measurements of ploidy by FICM and flow cytometry confirmed the accuracy of the FICM analyses. Thus, FICM appears to be an easy method for quantifying the DNA content of visually inspected cell nuclei in surgical pathology.

Cell cycle regulation of immunoglobulin class switch recombination and germ-line transcription: potential role of Ets family members

Previous studies have indicated that transcription of germ-line (GL) CH genes is necessary to obtain immunoglobulin (Ig) class switching. We report here a correlation between proliferation, switching and GL transcripts. Smu-S gamma 1 switch recombination in lipopolysaccharide (LPS) + interleukin-4 (IL-4)-activated mouse B cells was assayed by a digestion-circularization polymerase chain reaction. Switching to gamma 1 is reduced upon inhibition of DNA synthesis with hydroxy-urea (HU) or aphidicholin (AC). Incubation of activated B cells with HU severely reduces steady-state levels of GL gamma 1 and epsilon RNA. By utilizing elutriation to synchronize B cell blasts in different phases of the cell cycle, it was found that GL gamma 1 transcripts are mainly expressed in G1 and S phases, but not in G0. Using the electrophoretic mobility shift assay, we characterized two major LPS-induced complexes, which bind to the GL gamma 1 promoter and are expressed at levels which correlate with the amount of LPS-induced DNA synthesis. Furthermore, the intensity of the complexes is reduced when cells are arrested with the DNA synthesis inhibitors HU or AC. Elutriation experiments revealed that the complexes are expressed in G1 and S, but not in G0. They bind to an Ets consensus element near the major initiation sites used in proliferating cells. The possible implications of these findings for Ig isotype switching are discussed.

New epi-fluorescence optical system for independent analysis of two different fluorochromes in microscopy

A new epi-fluorescence optical system is described that uses splitting of the primary excitation and emission light beams, independent modification of the separated beams, and their reunification. The optical system was constructed for analysis of two different fluorochromes, e.g., DAPI and TRITC. Modifications in the separated beams comprise: (1) isolation of specific wavelengths (365 nm, 546 nm, 435-500 nm, and 590-750 nm), (2) wavelength switching without image displacement and blur by means of a light chopper alternating between ultraviolet-excitation/blue-detection and green-excitation/red-detection at frequencies of up to 140 Hz for observation by eye without image flicker, and (3) separate positioning of lenses for compensation of chromatic aberrations. This system demonstrates a good transmission of the chosen wavelengths. A high specificity of double fluorescence analysis with minimal effects of spectral overlap was obtained with good temporal resolution. It has been shown that it is feasable to obtain separate chromatic compensations for the use of a microscope objective in spectral regions outside the range for which the objective is corrected.

DNA synthesis after combined treatment with cisplatin and 5-fluorouracil of a mouse ascites tumor growing in vivo

We examined whether an increase in the salvage and/or the de novo synthesis of thymidine (TdR) can explain the elevated DNA synthesis rate found up to 15-20 h after combined treatment with cisplatin and 5-fluorouracil (5-FU), compared with single-drug regimen. The salvage and the de novo pathways of TdR in Bp8 mouse ascites tumor cells were reduced equally after the combined treatment and the single-drug treatments. The inhibition of the de novo pathway of TdR was confirmed by a reduced thymidylate synthase activity, as measured in cell extract. A marked imbalance of the deoxyribonucleotide triphosphates were found, in particular between the deoxypyrimidines. These imbalances were similar between the 5-FU single-drug treatment and combined treatment. We conclude that neither the extracellular TdR salvage nor the de novo synthesis of TdR explain the relatively elevated DNA synthesis rate after combined treatment. We suggest that the supra-additive effect of the combined treatment is due to an interaction between the elevated DNA synthesis, the imbalanced deoxyribonucleotides and the cisplatin-induced DNA cross-links, and possibly also due to a higher concentration of 5-FU incorporated into DNA.

Improved method for release of cell nuclei from paraffin-embedded cell material of squamous cell carcinomas

An improved method of releasing cell nuclei from paraffin-embedded highly keratinized squamous cell carcinomas by pretreatment with 85% formic acid-0.3% H2O2 followed by enzymatic treatment with subtilisin Carlsberg is described. After DAPI staining the resulting suspensions of cell nuclei were analyzed by DNA flow cytometry, in addition to microscopy. The total yield of released cell nuclei was improved and the proportion of tumor cell nuclei in the suspensions increased from 12% to 53% using this method compared to the conventional preparation technique. Cytoplasmic residue disappeared nearly completely. Thus, the finding of false aneuploid cell populations representing diploid cells with autofluorescent cytoplasm could be avoided. In addition, even small true aneuploid cell populations could be detected due to the increased proportion of released tumor cell nuclei and the lower proportion of background in the > 2C region.

Preparation of cell nuclei from fresh tissues for high-quality DNA flow cytometry

An easy method for preparation of bare cell nuclei from fresh solid tissues for DNA flow cytometry is described. Pieces of up to 2 x 2 x 2 mm3 size from fresh tissues were fixed in formalin. After removal of formalin by washing with ethanol and rehydration with tap water, the tissue pieces were incubated with subtilisin Carlsberg (pronase, Sigma protease XXIV) and then stained directly with DAPI. Staining with ethidium bromide gave unsatisfactory results. Neither mechanical disaggregation nor centrifugation were used. The resulting cell nucleus suspensions had extremely low frequencies of debris particles and of clumped cell nuclei. A good yield, a minimized loss, and a good stainability of cell nuclei were obtained. The applicability of the method was exemplified by the analysis of biopsies from the colon-rectum in patients with ulcerative colitis and of biopsies from the bladder in patients with bladder cancer and compared to the standard method of this laboratory, which uses mechanical disaggregation, ethanol fixation, pepsin treatment, and staining with ethidium bromide. The formalin-subtilisin Carlsberg technique resulted in good agreement of ploidy measurements compared to the standard method, a higher number of evaluable histograms, an improved detectability of aneuploid cell populations, and an improved accuracy of the S- and G2-phase analysis, particularly in samples with low proliferation. The method also makes it possible to use long-term storage and to transport samples by post.

Deoxyribonucleic acid ploidy of core biopsies and metastatic lymph nodes of prostate cancer patients: impact on time to progression. The European Organization for Research and Treatment of Cancer Genitourinary Group

We studied 98 patients with locally confined but lymph node positive prostatic cancer (1 stage T1, 29 stage T2, 55 stage T3 and 2 stage T4) who were not treated by radical prostatectomy. A retrospective analysis was done of deoxyribonucleic acid (DNA) ploidy of pretreatment core biopsies of the primary tumor and lymph node metastases. While DNA ploidy has been shown to be an important prognostic factor if applied to radical prostatectomy specimens, core biopsy specimens and nodal metastases have rarely been studied. Of the 98 patients 87 were evaluable for DNA ploidy: 45 (52%) had diploid, 13 (15%) had tetraploid and 29 (33%) had aneuploid tumors. The ploidy of the primary tumor and of the lymph node metastases correlated significantly with the rate of progression and interval to progression. Also, significant correlations were noted between the percentages of cells in the S phase or S plus G2 phases of the cell cycle and interval to progression. Most patients in this study are part of the European Organization for Research and Treatment of Cancer protocol 30846, a prospective randomized study of early versus delayed treatment in lymph node positive, otherwise locally confined prostate cancer. This study is ongoing. Early endocrine treatment was associated with a significantly longer interval to progression. In a Cox regression analysis of the prognostic factors involved in this study, early endocrine treatment was more important than ploidy or proliferation patterns. Stage (T category) and histopathological grade did not show a correlation with progression. Followup is still too short and the numbers of patients are too small for relevant subgroup analysis. DNA ploidy measurement by flow cytometry on archival (paraffin embedded) core biopsy and lymph node material is possible, and produces meaningful results in predicting the prognosis of prostatic cancer. Since this information can be made available before treatment decisions, its exact value in the management of locally confined prostate cancer can be determined.

The effects of cAMP on the expression of glycolytic isozymes in activated peripheral human T lymphocytes

Forskolin, an activator of adenylate cyclase, inhibits mitogen induction of glycolytic isozymes in human peripheral T cells. Inhibition of lactate dehydrogenase isozyme activity is correlated with lowered mRNA levels, suggesting a transcriptional block in the presence of increased cAMP. Forskolin added with the mitogen, or 12-24 h after the mitogen, strongly inhibits isozyme expression and DNA synthesis, and causes cells to accumulate in the G0 or early G1 phase of the cell cycle. The data suggest that DNA synthesis and isozyme expression are both inhibited by a cAMP-sensitive step(s) in the early activation or progression phase.

Flow sorting of tumor cells for morphometric analysis, particularly of rare cells

Using flow cytometric DNA measurement and sorting combined with morphometric light microscopy, different groups of cells were studied in a human melanoma pleural effusion, a human melanoma lymph node metastasis and a mouse tumor, as well as in normal reference tissues. Beside cells of the predominant tumor cell population, three types of rare tumor cells were studied after enrichment by sorting: a) giant cells from the greater than 8c region, comprising about 5% of the tumor cells, b) binucleated and multinucleated cells with unequal nuclear sizes within the same cell, found at frequencies of about 1.5%, and c) less than 2c cells which were derived from the so-called "debris"-region of the DNA histogram, found at frequencies of about 1 to 6%. All these rare cells were found only in the malignant tumors and not in the benign reference tissues. Morphometry showed that the increase in the cellular DNA content in the different fractions of tumor cells was combined with an increase in the cellular and nuclear sizes. However, the n/c-ratio was constant in the whole range of tumor cell fractions, including the fractions from the the less than 2c and the greater than 8c regions. The n/c-ratio of the less than 2c cells and giant cells differed from that of corresponding normal cells underlining their origin from the predominant tumor cell population. The possible linkage between the occurrence of the three rare cell types and genetic instability of tumors related to faulty nucleus and cell division is discussed.

Hydroxyurea-induced cell death in human T lymphoma cells as related to imbalance in DNA/protein cycle and deoxyribonucleotide pools and DNA strand breaks

The aim of this study was to elucidate the mechanism(s) behind the cellular toxicity of therapeutic concentrations of hydroxyurea (HU). Treatment of human T lymphoma cells (CCRF-CEM) with 60-100 microM of HU for 24 h decreased the growth rate by 90% due to accumulation of cells in early S phase. It induced a marked imbalance in both the DNA/protein cycle (as measured by two-parameter flow cytometry) and the deoxyribonucleotide (dNTP) pools. HU treatment did not enhance the frequency of DNA single-strand breaks (SSBs), as measured by the alkaline unwinding technique. Cell viability was unaffected. However, removal of HU led to 10-15% cell loss during the following 12 h period in parallel with increasing SSBs, and a rapid progression of cells through S and G2 stages. The unbalanced DNA to protein content per cell and the dNTP pools were normalized 6-12 and 24 h after removal of HU, respectively. These results show that marked changes in the DNA to protein ratio and dNTP pools alone are not directly lethal, but when combined with a high replicative DNA synthesis rate, as found after removal of HU, apparently lead to elevated cell death.

DNA ploidy in cell nuclei from paraffin-embedded material--comparison of results from two laboratories

In 49 pairs of contiguous sections from paraffin-embedded prostatic cancer tissue, the DNA indices (DIs) were determined by flow cytometry (FCM) at 2 different laboratories. In 3 of 45 pairs of evaluable nuclear suspensions, DIs of 1.1 (DNA aneuploid) were found at Laboratory 1, whereas all 3 tumours were classified as DNA diploid at Laboratory 2. In the remaining 42 specimens, the correlation between the DIs was excellent, though the application of strictly defined DNA ploidy ranges led to different DNA ploidy allocation in 3 cases. It is concluded that in 85-90% of the cases, reliable DIs can be obtained by FCM done in paraffin-embedded material at different laboratories. Slight technical variations and interpretation differences may lead to different ploidy allocation in 10-15% of the cases.

Expression of glycolytic isoenzymes in activated human peripheral lymphocytes: cell cycle analysis using flow cytometry

Human peripheral lymphocytes activated with concanavalin A and phorbol myristate ester exhibit an increase in glycolysis on a time-course similar to that for DNA synthesis. Elevated glycolysis is accompanied by increased specific activities of the glycolytic enzymes. Increased enzyme activities are accounted for by the appearance of specific isoenzyme forms (muscle forms) normally expressed in rapidly growing tumor cells or in growth-stimulated cells. In the present study we analyzed the expression of the glycolytic isoenzymes during cell cycle progression of activated human lymphocytes using two-parameter (DNA and protein) flow cytometry. Time-course studies and analysis of subpopulations prepared by elutriation centrifugation showed that the inducible isoenzymes are expressed at low levels or not at all in G0 cells. They are expressed first during the G0 to G1 transition or in early G1. However, expression increases throughout G1, reaching a maximum in S-phase. Thus, induction of glycolytic isoenzymes provides an excellent marker of T-cell activation and progression toward DNA synthesis.

An improved Hedley method for preparation of paraffin-embedded tissues for flow cytometric analysis of ploidy and S-phase

A modification of the Hedley-method for flow cytometric DNA analysis of paraffin-embedded tissues is presented. Dewaxed and dehydrated tissue from paraffin blocks was incubated with subtilisin Carlsberg (pronase, Sigma protease XXIV) and then stained directly without washing and centrifugation. The loss of material was minimized, which was advantageous, for example, for the analysis of core-biopsies, and all measured samples showed extremely low frequencies of clumped cell nuclei. This made is easier to detect polyploid nuclei and even rare nuclei of high ploidy could be identified. S-phase analyses were more precise, since the background originating from clumped debris particles was very low. The improved method was applied to the estimation of frequencies of high-polyploid nuclei found in various diploid, tetraploid, and aneuploid human myosarcomas of the uterus.

Modal DNA values and estramustine-binding protein (EMBP) as prognostic markers in prostatic cancer

In this study, we have investigated the model DNA values and the expression of estramustine-binding protein (EMBP) in formalin-fixed and paraffin-embedded TUR specimens from 76 untreated patients with prostatic cancer. In addition, specimens from 13 patients were analyzed for tumour EMBP expression only. Ploidy was measured as diploid, tetraploid and non-tetraploid aneuploid or aneuploid in the near-diploid region. All patients had been referred during 1978-1981, and were subjected to TUR due to urinary obstruction. Survival data were obtained for all patients through March 1988. Statistical analyses were performed using a Cox's regression model with respect to survival and cause specific survival and correlated to the DNA pattern and the expression of EMBP. The existence of a near-diploid aneuploid cell population as well as poor differentiation grade were both statistically significantly correlated with poor survival. Near-diploid aneuploid cell lines were seen in 9/76 (12%) of the patients and were also seen in well differentiated cancers (4/17). The expression of EMBP was most abundant in the moderately differentiated cancers. However, all prostatic cancer specimens investigated were positive for the antigen. Patients with poorly differentiated carcinomas and high EMBP expression showed a tendency towards better prognosis than those with poorly differentiated carcinomas and low EMBP expression. The present patient material was, however, too small to show a statistically significant correlation between EMBP and survival.

Two-wavelength mercury arc lamp excitation for flow cytometric DNA-protein analyses

Correlated DNA- and protein-determinations were performed using flow cytometry and DAPI-sulforhodamine 101 (SR101) staining. Two-wavelength UV-green excitation using a single HBO lamp was found to be superior to single wavelength UV excitation, since it resulted in a higher specificity in the SR101 measurements. The effects of overlapping in the emission spectra and of energy transfer from DAPI to SR101 were minimised. Different staining conditions and the specificity of SR101 staining were examined. No binding of SR101 to DNA and RNA could be detected. Good reproducibility was achieved in the protein measurements using human lymphocytes as an internal reference. Examples are given of the analysis of mixed cell populations with different cellular protein contents and different growth and metabolic activities. Correlated measurements of DNA and protein appear to be useful for further analysis of tumor cell populations.

The reproducibility of flow cytometric analyses in human tumors. Methodological aspects

Various methodological aspects of flow cytometry were studied in material from endometrial carcinoma, ovarian tumors and bladder carcinoma. Measurements of identical samples on two different occasions gave an excellent correlation of the obtained DNA values, r = 0.997 and a good reproducibility of the S-phase rate, r = 0.87. In large tumors different DNA values were found in 5/36 cases when central and surface biopsies were compared (indicating tumor heterogeneity) which stresses the importance of multiple biopsies. The S-phase rate of the surface biopsies was generally higher. Comparing staining with ethidium bromide and DAPI, a good correspondence of ploidy determinations in human bladder tumors was found, provided that diploid cells from the normal tissue component were used as internal reference. When ethidium bromide staining was used, there was a good agreement between the values of tumor ploidy obtained by external standardization using lymphocytes and internal standardization using diploid tumor cells, respectively. In DAPI staining with lymphocytes as an external standard the tumor ploidy was systematically overestimated by about 10% due to suboptimal staining of lymphocytes after 3 hours. This difference decreased after 18 hours of staining. Determination of S-phase fraction showed a good correlation between DAPI and ethidium bromide stained bladder tumor samples (r = 0.86). Human lymphocytes as an external standard showed good reproducibility. In conclusion, flow cytometric measurements of the ploidy level and S-phase rate are highly reproducible provided that tumor heterogeneity is taken into account and proper preparation and standardization methods are used.