CD8+ T cells in cutaneous T-cell lymphoma: expression of cytotoxic proteins, Fas Ligand, and killing inhibitory receptors and their relationship with clinical behavior

PURPOSE

We investigated the number, phenotype, and prognostic significance of CD8+ T cells in patients with mycosis fungoides (MF) and CD30- primary cutaneous large T-cell lymphoma (PCLTCL).

PATIENTS AND METHODS

Immunohistochemical stainings for CD8, granzyme B (GrB), T cell-restricted intracellular antigen (TIA-1), Fas ligand (FasL), and killer-cell inhibitory receptors (KIRs; CD95, CD158a, and CD158b) were performed on 83 first-diagnostic biopsy samples obtained from patients with plaque-stage MF (n = 42), tumor-stage MF (n = 20), and CD30- PCLTCL (n = 21).

RESULTS

Serial sections and double-staining experiments showed that the large majority of CD8+ T cells in MF and CD30- PCLTCL expressed TIA-1 and FasL, whereas only a minority expressed GrB, which suggested that these CD8+ T cells were partly activated cytotoxic T lymphocytes (CTLs). These CD8+ CTLs never or rarely expressed KIRs. This phenotype was a constant feature of CD8+ CTLs and did not alter with disease progression. In contrast, the median percentage of CD8+ CTLs in plaque-stage MF (22%), tumor-stage MF (7%), and CD30- PCLTCL (3%) differed significantly (P < .0001) and was associated with a significant decrease in 5-year survival. Also within the group of tumor-stage MF, a significant relation between CD8+ CTLs and survival was found. Multivariate analysis in the total group of MF demonstrated that both skin stage and percentage of CD8+ CTLs were independent parameters of survival.

CONCLUSION

Our results demonstrated that partly activated CD8+ CTLs were present in CTCL and that high proportions of these cells correlated with a better prognosis. This suggested that these CD8+ CTLs could play an important role in the antitumor response in these conditions.

Prevalence of anti-human papillomavirus type 16, 18, 31, and 58 virus-like particles in women in the general population and in prostitutes

Genital human papillomavirus (HPV) infection is sexually transmitted. The aim of the study was to characterize serological responses to HPV types 16, 18, 31, and 58 by exploring type-specific virus-like particles (VLPs) in two groups of women with very distinct sexual behaviors. Anti-VLP antibodies for types 16, 18, 31, and 58 and HPV DNA in cervical cells were investigated with 177 prostitutes and 283 age-matched controls from the female general population in Spain. Anti-VLP positivity increased with number of lifetime sexual partners in women from the general population, and no seroresponse was found in virgins. However, in prostitutes HPV infection was characterized by higher multireactivity to three or four VLPs (25%) than the general population (3%) and by a more frequent antibody response to HPV-58 than in the general population. About 75% of the women seropositive for type 58 had been born in a Latin American country. Seroprevalence of HPV and cervical HPV DNA in prostitutes were 14 and 10 times higher than observed in women in the general population (prevalence odds ratio [POR] of HPV seropositivity, 14.04 [95%; CI = 8.4 to 23.6] and POR for HPV DNA, 10.4 [95% CI = 3.9 to 27.6). Our results indicate that prostitutes are at an increased risk of oncogenic HPV infections, and they confirm the validity of anti-VLPs as markers of present or past HPV infection, that the number of sexual partners is the major determinant in acquisition of oncogenic HPV, and that anti-VLPs could be used as a marker of repeated infection in prostitutes.

Cytological regression and clearance of high-risk human papillomavirus in women with an abnormal cervical smear

We studied the natural course of high-risk human papillomavirus (HPV) infection and cytological regression in women referred for colposcopy because of abnormal cervical smears. We found that high-risk HPV clearance preceded regression of cervical lesions by an average of 3 months. The cumulative 1-year rate of cytological regression was similar in women with mild and moderate dyskaryotic cervical smears. Thus, retesting of high-risk HPV after 6 months in women with mild to moderate dyskaryosis predicts cytological regression.

High-risk HPV testing in women with borderline and mild dyskaryosis: long-term follow-up data and clinical relevance

In The Netherlands and most other European countries, women with two serial cervical smears with borderline or mild dyskaryosis (BMD) within 6 months are referred for colposcopy-directed biopsies. Only about 10% of these women have high-grade cervical intraepithelial neoplasia (CIN). This study therefore investigated whether human papillomavirus (HPV) testing could identify which women with smears read as BMD are most likely to have high-grade CIN, either at referral or during follow-up and the relationship was determined between clearance of high-risk HPV and regression of abnormal cytology. Women with smears read as BMD (n=278) were referred to the gynaecologist for colposcopy. They were subdivided into two groups; group A comprised women with a single smear (n=172) and group B women with two sequential smears (n=106) read as BMD before referral. High-risk HPV detection with Hybrid Capture II (HC II) was performed on a cervical scrape taken at the first visit before colposcopy (i.e. baseline smear) and during follow-up. Biopsies were taken when lesions suspected for CIN were seen at colposcopy. High-risk HPV DNA was present in the baseline smears of 126 (45.0%) women; 26 (20.6%) of them had histologically confirmed CIN 2/3 at the first visit and another 14 (11.1%) during follow-up. Only one of the 152 women (0.7%) with a negative high-risk HPV test had a CIN 2 lesion at the first visit and no CIN lesions were detected during follow-up of these women. After exclusion of women who were treated for prevalent high-grade CIN, the median follow-up times were 1.3 years (range 0.0-4.3 years) and 1.6 years (range 0.0-4.5 years) for women with HPV-negative and HPV-positive baseline smears, respectively. The sensitivity of a positive high-risk HPV test for CIN 2/3 at the first visit was 96.3%, the specificity 60.2%, the positive predictive value 20.6%, and the negative predictive value 99.3%. These values did not change markedly when stratified for group A or group B. Thus, a high-risk HPV positive test was strongly associated with the presence at the first visit and the development of CIN 2/3 lesions during follow-up. Moreover, regression of abnormal cytology in women with a positive high-risk HPV test at baseline was strongly associated with viral clearance and occurred 0.3 years (range -1.2 to 1.7 years) later than HPV clearance. This study establishes the value of a high-risk HPV positive test for women at risk of high-grade CIN, with virtually no risk for missing CIN 2/3. Addition of a test on high-risk HPV in women with BMD could prevent 55% of the referrals and/or repeat smears.

Prognostic value of morphometry in patients with normal breast tissue or usual ductal hyperplasia of the breast

Women with usual ductal hyperplasia have a relative risk of 1.6-1.9 of subsequent breast cancer development. This slightly increased risk is generally not considered sufficiently high to justify (chemo)preventive therapy. It is therefore important to identify high-risk ductal hyperplastic lesions that would benefit from such a treatment. Nuclear morphometric features have been shown in previous work to be useful for objectively describing morphologic features associated with high risk in (pre)invasive breast lesions. The aim of this study was to evaluate whether such morphometric features can also predict subsequent invasive cancer development in patients with the common pattern of usual ductal hyperplasia or a normal breast biopsy. The present case-control study included 423 women with normal breast biopsies (n = 89) or biopsies containing usual ductal hyperplasia (n = 334). Of these 423 women, 132 developed invasive breast cancer during follow-up (mean 16.7 +/- 7.0 years). On the original hematoxylin and eosin-stained sections, nuclear morphometry was performed with a digitizing video overlay system, and mitotic and apoptotic indices were assessed. Patients with mean nuclear feature values for area, perimeter, diameter or longest axis above the 75th percentile had 1.6-1.7 times the breast cancer risk of women with mean nuclear feature values below this value. Pairwise combinations of these features yielded slightly higher cancer risks for the fourth quartile patients, with the highest risk (1.9) for patients with SD of nuclear area and perimeter values above the 75th percentile. The number of apoptotic or mitotic cells had no prognostic value for patients with apparently normal tissue or usual ductal hyperplasia. Our results give a first indication that normal breast tissue or usual ductal hyperplasia harbor nuclear morphologic changes that, when assessed by morphometry, may be used to predict breast cancer development. It is worthwhile studying this further in independent groups of patients with long-term follow-up.

Differential expression of human Polycomb group proteins in various tissues and cell types

Polycomb group proteins are involved in the maintenance of cellular identity. As multimeric complexes they repress cell type-specific sets of target genes. One model predicts that the composition of Polycomb group complexes determines the specificity for their target genes. To study this hypothesis, we analyzed the expression of Polycomb group genes in various human tissues using Northern blotting and immunohistochemistry. We found that Polycomb group expression varies greatly among tissues and even among specific cell types within a particular tissue. Variations in mRNA expression ranged from expression of all analyzed Polycomb group genes in the heart and testis to no detectable Polycomb group expression at all in bone marrow. Furthermore, each Polycomb group gene was expressed in a different number of tissues. RING1 was expressed in practically all tissues, while HPH1 was expressed in only a few tissues. Also within one tissue the level of Polycomb group expression varied greatly. Cell type-specific Polycomb group expression patterns were observed in thyroid, pancreas, and kidney. Finally, in various developmental stages of fetal kidney, different Polycomb group expression patterns were observed. We conclude that Polycomb group expression can vary depending on the tissue, cell type, and development stage. Polycomb group complexes can only be composed of the Polycomb group proteins that are expressed. This implies that with cell type-specific Polycomb group expression patterns, cell type-specific Polycomb group complexes exist. The fact that there are cell type-specific Polycomb group targets and cell type-specific Polycomb group complexes fits well with the hypothesis that the composition of Polycomb group complexes may determine their target specificity. J. Cell. Biochem. Suppl. 36: 129-143, 2001.

Distinct chromosomal aberrations in Epstein-Barr virus-carrying gastric carcinomas tested by comparative genomic hybridization

BACKGROUND & AIMS

Approximately 10% of gastric adenocarcinomas carry the human pathogenic Epstein-Barr virus (EBV). The role of EBV in the pathogenesis of these carcinomas remains to be established.

METHODS

To obtain a comprehensive overview of chromosomal aberrations in EBV-carrying and EBV-negative gastric carcinomas we performed comparative genomic hybridization (CGH) on 44 gastric carcinomas, 10 EBV-positive, and 34 EBV-negative. Additionally, DNA flow cytometry was done.

RESULTS

Loss of chromosome 4p (P < 0.001) and of 11p (P < 0.02) was exclusively restricted to EBV-carrying gastric carcinomas. In addition, loss of 18q (P < 0.02) was significantly more frequent in EBV-carrying gastric carcinomas. The latter involves loci, which have already been linked to gastric carcinogenesis such as the DCC and SMAD4 gene. In contrast, the losses on chromosome 4 and 11 do not yet harbor a gene related to gastric carcinogenesis. No significant correlation was found between DNA-ploidy and the EBV-status. A number of chromosomal aberrations were found at comparable frequencies in both groups, i.e., losses of chromosome 17, 12q, and loss of 1p. Interestingly, gains of 13q (10/34) and 3q (5/34) and loss of 1q (5/34) were solely observed in EBV-negative gastric carcinomas.

CONCLUSIONS

These data indicate that EBV-carrying and EBV-negative gastric carcinomas have different pathogenetic pathways in which EBV might play a crucial role.

Prognostic factors in primary cutaneous large B-cell lymphomas: a European multicenter study

PURPOSE

Most primary cutaneous B-cell lymphomas have an excellent prognosis. However, primary cutaneous large B-cell lymphomas (PCLBCLs) of the leg have been recognized as a distinct entity with a poorer prognosis in the European Organization for Research and Treatment of Cancer (EORTC) classification. This distinction on the basis of site has been debated. Our aim was to identify independent prognostic factors in a large European multicenter series of PCLBCL.

PATIENTS AND METHODS

The clinical and histologic data of 145 patients with PCLBCL were evaluated. According to the EORTC classification, 48 patients had a PCLBCL of the leg and 97 had a primary cutaneous follicle center-cell lymphoma (PCFCCL). Data from both groups were compared. Univariate and multivariate analyses of specific survival were performed using a Cox proportional hazards model.

RESULTS

Compared with PCFCCL, PCLBCL-leg were characterized by an older age of onset, a more recent history of skin lesions, a more frequent predominance of tumor cells with round nuclei and positive bcl-2 staining, and a poorer 5-year disease-specific survival rate (52% v 94%; P <.0001). Univariate survival analysis in the entire study group showed that older age, a more recent onset of skin lesions, the location on the leg, multiple skin lesions, and the round-cell morphology were significantly related to death. In multivariate analysis, the round-cell morphology (P <.0001), the location on the leg (P =.002), and multiple skin lesions (P =.01) remained independent prognostic factors. The round-cell morphology was an adverse prognostic factor both in PCLBCL-leg and in PCFCCL, whereas multiple skin lesions were associated with a poor prognosis only in patients with PCLBCL-leg.

CONCLUSION

With site, morphology, and number of tumors taken into account, guidelines for the management of PCLBCL are presented.

Absence of tpr-met and expression of c-met in human gastric mucosa and carcinoma

The c-met proto-oncogene, encoding the hepatocyte growth factor receptor, can be activated by various mechanisms. These include, among others, gene amplification with concomitant overexpression and the tpr-met oncogenic rearrangement. In the case of gastric cancer, contradictory results on the presence of the tpr-met oncogenic rearrangement have been published. The current study aimed therefore to assess the prevalence of tpr-met expression in Caucasian gastric adenocarcinomas, to evaluate the importance of this oncogene in their carcinogenesis. In addition, the level of c-met expression was determined, to evaluate the role of this alternative mode of activation of the proto-oncogene. A series of Caucasian gastric adenocarcinomas (n=43) and normal gastric mucosal samples (n=14) was analysed for tpr-met and c-met expression. Expression of tpr-met mRNA in the samples was performed by two reverse transcriptase polymerase chain reaction (RT-PCR) assays, with excellent correlation. The specificity of both methods was confirmed by direct sequencing of the PCR products of the MNNG-HOS cell line, which is known to contain the rearrangement. The level of c-met expression was assessed using semi-quantitative RT-PCR assays and immunohistochemistry (IHC). None of the normal gastric mucosal or gastric adenocarcinoma samples expressed tpr-met mRNA, as determined by both RT-PCR assays. Seventy per cent of the adenocarcinomas showed overexpression of c-met, according to elevated c-met mRNA levels, compared with the expression level of normal gastric mucosa. A significant correlation was found between the level of c-met mRNA and protein expression. In conclusion, these results strongly suggest that tpr-met activation does not play a role in Caucasian gastric carcinogenesis, while overexpression of the c-met gene occurs in the majority of Caucasian gastric adenocarcinomas.

Cost effectiveness analysis of a population based screening programme for asymptomatic Chlamydia trachomatis infections in women by means of home obtained urine specimens

OBJECTIVES

To evaluate the cost effectiveness of a systematic screening programme for asymptomatic Chlamydia trachomatis infections in a female inner city population. To determine the sensitivity of the cost effectiveness analysis to variation in the probability of developing sequelae.

METHODS

A decision tree was constructed to evaluate health effects of the programme, such as averted sequelae of chlamydial infection. Cost effectiveness from a societal perspective was estimated for screening by means of a ligase chain reaction on mailed, home obtained urine specimens, in a population with a C trachomatis test prevalence of 2.9%. An extensive sensitivity analysis was performed for the probability of sequelae, the percentage of preventable pelvic inflammatory disease (PID), and the discount rate.

RESULTS

The estimated net cost of curing one woman, aged 15-40 years, of a C trachomatis infection is US$1210. To prevent one major outcome (PID, tubal factor infertility, ectopic pregnancy, chronic pelvic pain, or neonatal pneumonia), 479 women would have to be screened. The net cost of preventing one major outcome is $15 800. Changing the probability of PID after chlamydial infection from 5% to 25% decreases the net cost per major outcome averted from $28 300 to $6380, a reduction of 78%. Results were less sensitive to variations in estimates for other sequelae. The breakeven prevalence of the programme ranges from 6.4% for the scenario with all probabilities for complications set at the maximum value to a prevalence of 100% for probabilities set at the minimum value.

CONCLUSIONS

Systematic screening of all women aged 15-40 years for asymptomatic C trachomatis infections is not cost effective. Although the results of the analyses are sensitive to variation in the assumptions, the costs exceed the benefits, even in the most optimistic scenario.

HPV presence precedes abnormal cytology in women developing cervical cancer and signals false negative smears

In a retrospective case-control study, we investigated high-risk HPV DNA presence by general primer GP5+/6+ PCR in the last normal cervical smear in the patient archives (i.e. baseline smear) of 57 women who later developed cervical cancer. Also, normal cervical smears of 114 age-matched control women were analysed. High-risk HPV DNA was detected in 37 of the 57 (65%) baseline smears of the case women, and 7 (6%) of 114 smears of the control women (OR 28, 95% Cl 11-72). The HPV positive subsequent smears and cervical cancer biopsies of the case women contained the same HPV type as was detected in the baseline smear. After cytological revision, the baseline smears of 48 case women (84%) were reclassified as abnormal, 33 (69%) of which scored high-risk HPV DNA positive. Ultimately, an undisputable normal baseline smear was found in only 10 case women. In 7 (70%) of them this smear was HPV positive, whereas only 7 (7%) of 104 revised, undisputable normal smears of control women were high-risk HPV positive (OR 32, 95% Cl 6.8-153). The results showed that (1) high-risk HPV presence precedes abnormal cytology in women who develop cervical cancer, and (2) high-risk HPV testing signals false-negative smears of women at risk of cervical cancer.

Lymphomatoid papulosis with a natural killer-cell phenotype

Lymphomatoid papulosis (LyP) is defined as a recurrent self-healing papulonodular eruption with the histological features of a (CD30+) cutaneous T-cell lymphoma. The atypical cells usually have a CD3+/-, CD4+/-, CD8-, CD30+, CD56- T-cell phenotype. We report an unusual case of LyP, in which the atypical cells expressed a CD3-, CD4-, CD8-, CD30+, CD56+ phenotype. Detailed phenotypic and genotypic analysis confirmed that these cells had a natural killer (NK)-cell phenotype. Lymphomas with an NK-cell phenotype usually have a poor prognosis. However, the waxing and waning of papular lesions for more than 20 years and the excellent response to low-dose oral methotrexate in this patient suggest similar clinical behaviour to LyP cases with a T-cell phenotype.

Biological evidence that human papillomaviruses are etiologically involved in a subgroup of head and neck squamous cell carcinomas

High-risk human papillomaviruses (HPVs) have been proposed to be associated with a subset of head and neck cancers (HNSCCs). However, clear biological evidence linking HPV-mediated oncogenesis to the development of HNSCC is hardly available. An important biological mechanism underlying HPV-mediated carcinogenesis is the inactivation of p53 by the HPV E6 oncoprotein. In the present study we investigated this biological relationship between HPV and HNSCC. In total 84 HNSCC tumors were analyzed for the presence of high-risk HPV nucleic acids by DNA polymerase chain reaction-enzyme immunoassay (PCR-EIA) and E6 reverse transcriptase (RT)-PCR as well as for the presence of mutations in the p53 gene. We found 20/84 HPV16 DNA-positive cases with one or more DNA assays, 10 of which were consistently positive with all assays. Only 9/20 cases showed E6 mRNA expression, indicative for viral activity. Only these nine E6 mRNA-positive cases all lacked a p53 mutation, whereas both the other HPV DNA-positive and HPV-DNA negative tumors showed p53 mutations in 36% and 63% of the cases, respectively. Moreover, only in lymph node metastases of HPV E6 mRNA-positive tumors both viral DNA and E6 mRNA were present. Our study provides strong biological evidence for a plausible etiological role of high-risk HPV in a subgroup of HNSCC. Analysis of E6 mRNA expression by RT-PCR or alternatively, semiquantitative analyses of the viral load, seem more reliable assays to assess HPV involvement in HNSCC than the very sensitive DNA PCR analyses used routinely.

Similarity in expression of cell cycle proteins between in situ and invasive ductal breast lesions of same differentiation grade

There is increasing evidence that there are different progression routes leading to invasive breast cancer, depending on histology and differentiation grade. The aim of this study was to determine alterations in the expression of proteins involved in proliferation and apoptosis in non-invasive and invasive ductal breast lesions. Immunohistochemistry was performed on 106 usual ductal hyperplasias (UDH), 61 DCIS lesions and 53 invasive ductal breast carcinomas. Increased proliferation (Ki67), overexpression of cyclin D1, HER-2/neu, p21 and p53, and decreased expression of bcl-2 and p27 could already be found in UDH. Significant differences between UDH and DCIS lesions were found for only one protein when UDH was compared with well-differentiated DCIS (p27), for three proteins when compared with intermediately differentiated DCIS (p21, cyclin D1, Ki-67), and for all proteins when compared with poorly-differentiated DCIS. Comparing DCIS with invasive lesions of same differentiation grade, proliferation was elevated in the invasive lesions. Altered expression of the other proteins was in general only slightly increased in the invasive lesion compared with DCIS. The number of proteins with altered expression per lesion was highest in poorly-differentiated lesions and was comparable between DCIS and invasive cancer of the same differentiation grade. In conclusion, the biggest changes in expression of these proliferation and apoptosis related proteins appear to occur during the transition from hyperplasia to DCIS; they probably play a minor role in the transition from DCIS to invasive breast lesion of same differentiation grade. Well-differentiated in situ and invasive breast lesions share many of the aberrations in expression of these proteins, as do poorly-differentiated in situ and invasive lesions. However, there are many differences between the well and poorly-differentiated lesions. This further supports the existence of different progression routes leading to breast cancer.

Coexpression of BMI-1 and EZH2 polycomb-group proteins is associated with cycling cells and degree of malignancy in B-cell non-Hodgkin lymphoma

Polycomb-group (PcG) proteins, such as BMI-1 and EZH2, form multimeric gene-repressing complexes involved in axial patterning, hematopoiesis, and cell cycle regulation. In addition, BMI-1 is involved in experimental lymphomagenesis. Little is known about its role in human lymphomagenesis. Here, BMI-1 and EZH2 expression patterns are analyzed in a variety of B-cell non-Hodgkin lymphomas (B-NHLs), including small lymphocytic lymphoma, follicular lymphoma, large B-cell lymphoma, mantle-cell lymphoma, and Burkitt lymphoma. In contrast to the mutually exclusive pattern of BMI-1 and EZH2 in reactive follicles, the neoplastic cells in B-NHLs of intermediate- and high-grade malignancy showed strong coexpression of BMI-1 and EZH2. This pattern overlapped with the expression of Mib-1/Ki-67, a marker for proliferation. Neoplastic cells in B-NHL of low-grade malignancy were either BMI-1(low)/EZH2(+) (neoplastic centroblasts) or BMI-1(low)EZH2(-) (neoplastic centrocytes). These observations show that low-, intermediate-, and high grade B-NHLs are associated with increased coexpression of the BMI-1 and EZH2 PcG proteins, whose normal expression pattern is mutually exclusive. This expression pattern is probably caused by a failure to down-regulate BMI-1 in dividing neoplastic cells, because BMI-1 expression is absent from normal dividing B cells. These observations are in agreement with findings in studies of Bmi-1 transgenic mice. The extent of BMI-1/EZH2 coexpression correlated with clinical grade and the presence of Mib-1/Ki-67 expression, suggesting that the irregular expression of BMI-1 and EZH2 is an early event in the formation of B-NHL. This points to a role for abnormal PcG expression in human lymphomagenesis. (Blood. 2001;97:3896-3901)

Telomerase suppression by chromosome 6 in a human papillomavirus type 16-immortalized keratinocyte cell line and in a cervical cancer cell line

BACKGROUND

High-risk human papillomavirus (HPV) types play a major role in the development of cervical cancer in vivo and can induce immortalization of primary human keratinocytes in vitro. Activation of the telomere-lengthening enzyme telomerase constitutes a key event in both processes. Because losses of alleles from chromosome 6 and increased telomerase activity have been observed in high-grade premalignant cervical lesions, we analyzed whether human chromosome 6 harbors a putative telomerase repressor locus that may be involved in HPV-mediated immortalization.

METHODS

Microcell-mediated chromosome transfer was used to introduce chromosomes 6 and 11 to the in vitro generated HPV type 16 (HPV16)-immortalized keratinocyte cell line FK16A and to the in vivo derived HPV16-containing cervical cancer cell line SIHA: Hybrid clones were analyzed for growth characteristics, telomerase activity, human telomerase reverse transcriptase (hTERT) and HPV16 E6 expression, and telomere length. FK16A hybrid clones were also transduced with an hTERT-containing retrovirus to examine the effect of ectopic hTERT expression on growth. Statistical tests were two-sided.

RESULTS

Introduction of human chromosome 6 but not of chromosome 11 to both cell lines yielded hybrid cells that demonstrated crisis-like features (i.e., enlarged and flattened morphology, vacuolation, and multinucleation) and underwent growth arrest after a marked lag period. In the chromosome 6 hybrid clones analyzed, telomerase activity and hTERT messenger RNA (mRNA) expression were statistically significantly reduced compared with those in the chromosome 11 hybrid clones (for telomerase activity, P =.004 for the FK16A hybrids and P =.039 for the SiHa hybrids; for hTERT mRNA expression, P =.003 for the FK16A hybrids). The observed growth arrest was associated with telomeric shortening. Ectopic expression of hTERT in FK16A cells could prevent the telomeric shortening-based growth arrest induced by chromosome 6.

CONCLUSIONS

Chromosome 6 may harbor a repressor of hTERT transcription, the loss of which may be involved in HPV-mediated immortalization.

Distinct BMI-1 and EZH2 expression patterns in thymocytes and mature T cells suggest a role for Polycomb genes in human T cell differentiation

BMI-1 and EZH2 Polycomb-group (PcG) proteins belong to two distinct protein complexes involved in the regulation of hematopoiesis. Using unique PcG-specific antisera and triple immunofluorescence, we found that mature resting peripheral T cells expressed BMI-1, whereas dividing blasts were EZH2(+). By contrast, subcapsular immature double-negative (DN) (CD4(-)/CD8(-)) T cells in the thymus coexpressed BMI-1 and EZH2 or were BMI-1 single positive. Their descendants, double-positive (DP; CD4(+)/CD8(+)) cortical thymocytes, expressed EZH2 without BMI-1. Most EZH2(+) DN and DP thymocytes were dividing, while DN BMI-1(+)/EZH2(-) thymocytes were resting and proliferation was occasionally noted in DN BMI-1(+)/EZH2(+) cells. Maturation of DP cortical thymocytes to single-positive (CD4(+)/CD8(-) or CD8(+)/CD4(-)) medullar thymocytes correlated with decreased detectability of EZH2 and continued relative absence of BMI-1. Our data show that BMI-1 and EZH2 expression in mature peripheral T cells is mutually exclusive and linked to proliferation status, and that this pattern is not yet established in thymocytes of the cortex and medulla. T cell stage-specific PcG expression profiles suggest that PcG genes contribute to regulation of T cell differentiation. They probably reflect stabilization of cell type-specific gene expression and irreversibility of lineage choice. The difference in PcG expression between medullar thymocytes and mature interfollicular T cells indicates that additional maturation processes occur after thymocyte transportation from the thymus.

Selective gene delivery toward gastric and esophageal adenocarcinoma cells via EpCAM-targeted adenoviral vectors

Application of recombinant adenoviral vectors for cancer gene therapy is currently limited due to lack of specificity for tumor cells. For gastric and esophageal adenocarcinoma, we present here that the relative abundant expression of the primary adenovirus receptor, coxsackie/adenovirus receptor (CAR), on normal epithelium compared to carcinoma favors the transduction of the epithelium. As such, to achieve specific transduction of cancer cells, targeting approaches are required that ablate the binding of the virus to CAR and redirect the virus to tumor-specific receptors. By immunohistochemistry and reverse transcriptase polymerase chain reaction assays, we demonstrate a marked difference in expression of the human epithelial cell adhesion molecule (EpCAM) between normal and (pre)malignant lesions of the stomach and esophagus. Based on this, we explored the feasibility of using EpCAM to achieve gastric and esophageal adenocarcinoma selective gene transfer. Adenoviral vectors redirected to EpCAM using bispecific antibodies against the adenovirus fiber-knob protein and EpCAM specifically infected gastric and esophageal cancer cell lines. Using primary human cells, an improved ratio of tumor transduction over normal epithelium transduction was accomplished by the EpCAM-targeted vectors. This study thus indicates that EpCAM-targeted adenoviral vectors may be useful for gastric and esophageal cancer-specific gene therapy in patients.

Activity of the EBNA1 promoter associated with lytic replication (Fp) in Epstein-Barr virus associated disorders

BACKGROUND/AIMS

In Epstein-Barr virus (EBV) positive cell lines that are stably infected, three different promoters are known to direct the transcription of EBV nuclear antigen 1 (EBNA1). These are located in the BamHI-C, BamHI-Q, and BamHI-F regions of the viral genome (Cp, Qp, and Fp, respectively). Fp is activated upon induction of the viral lytic cycle. The aim of this study was to investigate the activity of Fp in EBV associated diseases.

METHODS

Using reverse transcriptase polymerase chain reaction, a qualitative analysis of EBNA1 promoter usage in various EBV associated diseases was performed.

RESULTS

Fp driven transcription was detected in the context of primary infection and/or lytic replication; at least a portion of the Fp driven transcripts encoded EBNA1. Qp driven EBNA1 transcripts were detected in most samples across the range of disorders tested. Cp driven EBNA1 transcripts were detected in the context of immune suppression and in samples containing EBV positive (non-neoplastic) lymphoid cells.

CONCLUSIONS

These results confirm the previously proposed "housekeeping" function of the Qp promoter.

Pathologic analysis of sentinel lymph nodes

The sentinel lymph node (SLN) procedure enables selective targeting of the first draining lymph node, where the initial metastases will form. A negative SLN predicts the absence of tumor metastases in the other regional lymph nodes with a high degree of accuracy. This means that in case of a negative SLN, regional lymph node dissection is no longer necessary. Besides saving patients the significant morbidity associated with lymph node dissection, it will also save costs. Crucial for the success of the SLN procedure is the screening of the SLN for metastases by the pathologist. To this end, several techniques are available such as standard histo- and cytopathological techniques, immunohistochemistry, flow cytometry, and molecular biological techniques. In this paper, the value of these methods for detecting SLN metastases is discussed. Some of these techniques have also appeared to be quite useful for intraoperative evaluation of SLNs. The standard protocol for detection of SLN metastases consists of extensive histopathological investigation including stepped sections stained with hematoxylin and eosin (HE) and immunohistochemistry. Intraoperative frozen section analysis and imprint cytology of SLNs have been shown to be reasonably reliable for detecting breast cancer metastases in SLNs. Further studies are necessary to establish the role of multiparameter flow cytometry and sophisticated molecular biological techniques such as reverse transcription polymerase chain reaction (RT-PCR) in detecting SLN metastases.