Different expression of P14ARF defines two groups of breast carcinomas in terms of TP73 expression and TP53 mutational status

In 95 breast carcinomas, we investigated P14ARF and TP73 mRNA expression and their relationship to TP53 mutations, determined by an immunohistochemical method, studying several clinicopathologic features of the tumors. P14ARF and TP73 mRNA levels were determined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR), using beta-actin as a control. P14ARF was overexpressed in 19% of the cases and underexpressed in 24%. TP73 was overexpressed in 22% of the tumors, and normal levels were found in the remaining 78%. The analysis of TP53 showed positive immunostaining in 38% of cases. The association of P14ARF and TP73 overexpression was statistically significant, as was the association between positive TP53 staining and TP73 overexpression. P14ARF was related to TP53 only in those cases in which there was low expression of P14ARF. Concomitant overexpression of P14ARF and TP73 was statistically related to positive TP53 immunostaining. The analysis of concomitant P14ARF and TP73 overexpression and clinicopathologic parameters of the tumors showed a statistically significant difference with respect to peritumoral vessel invasion (P = 0.01), lymph node metastasis (P = 0.03), negative ERBB2 expression (P = 0.005), and more advanced pathologic stages (P = 0.03). These results suggest that overexpression of P14ARF and TP73 could be implicated in breast carcinoma tumorigenesis and, ultimately, in the phenotypic features of these lesions.

The c-Jun NH(2)-terminal protein kinase/AP-1 pathway is required for efficient apoptosis induced by vinblastine

Vinblastine is an important antitumor agent that induces G(2)-M arrest and subsequent apoptosis in a wide variety of cell lines, but the molecular mechanisms that link mitotic arrest and apoptosis are poorly understood. The AP-1 transcription factor has been implicated in many critical cellular processes, including apoptosis, and is a major target of the c-Jun NH(2)-terminal kinase signaling pathway that is activated by vinblastine and other microtubule inhibitors. In this study we sought to determine the role of c-Jun NH(2)-terminal kinase/AP-1 in the response of KB3 carcinoma cells to vinblastine. For this purpose, we generated KB3 cell lines that stably expressed the c-Jun dominant-negative deletional mutant TAM67, which lacks the NH(2)-terminal transactivation domain. KB3-TAM67 cell lines displayed normal growth kinetics and essentially unaltered basal AP-1 activity, but vinblastine-induced phosphorylation of c-Jun and activating transcription factor-2, and AP-1 activation, were strongly inhibited. KB3-TAM67 cell lines arrested normally at G(2)-M in response to vinblastine, but were significantly more resistant to the drug, exhibiting markedly delayed apoptosis and increased overall survival, relative to control cells. To investigate the underlying mechanisms, differential expression of apoptotic regulatory genes was monitored by immunoblot and cDNA microarray analysis. We found that vinblastine treatment caused down-regulation of p53 and its target p21 and up-regulation of tumor necrosis factor alpha, Bak, and several other genes in control but not in KB3-TAM67 cells, identifying these genes as putative targets of vinblastine-inducible AP-1. These results demonstrate that vinblastine-inducible AP-1 plays a destructive, proapoptotic role and may do so by regulating the expression of a specific subset of target genes that promotes efficient apoptotic cell death following mitotic arrest.

Leiomyosarcoma of the vulva. A case report

BACKGROUND

Leiomyosarcoma of the vulva is a rare mesenchymal tumor. Biologic features of a low grade tumor were investigated by an immunohistochemical workup.

CASE

A 38-year-old woman presented with a slowly growing vulvar mass. Surgical treatment was performed, and a low grade leiomyosarcoma of the vulva was diagnosed. Immunohistochemical reactions were performed with monoclonal antibodies against desmin, vimentin, smooth muscle actin, cytokeratin, S-100 protein, estrogen, progesterone and androgen receptor, p53 protein, Ki-67 antigen, leukocyte common antigen and polyclonal antibodies to factor VIII-related antigen. Expression of estrogen, progesterone and androgen receptor was present in addition to a moderate number of Ki-67-positive cells and absence of p53 protein overexpression and lymphatic cell infiltration besides adequate microvessel density for smooth muscle tumors. Since the immunohistochemical markers indicated a less aggressive tumor, any further adjuvant therapy was rejected. The patient was without recurrence 24 months later.

CONCLUSION

The immunohistologic profile proved the low histologic grade of vulvar leiomyosarcoma. The findings helped to estimate prognosis and plan therapy.

Measures of cell turnover (proliferation and apoptosis) and their association with survival in breast cancer

Our objective was to investigate the prognostic significance of cell turnover (apoptosis and proliferation) in breast cancer patients. Apoptosis was microscopically quantitated on histological sections from 791 breast cancer patients with long-term follow-up (median, 16.3 years). Apoptotic counts were also compared with proliferation data (mitotic counts and MIB-1 labeling); apoptosis data derived from terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay; and pathobiological variables, including p53, erbB-2, and estrogen receptor (ER). High apoptotic counts were associated with increased cellular proliferation, ER negativity, immunopositivity of erbB-2 and p53 (P < 0.0001), and shortened disease-specific survival (DSS; P = 0.0009) and disease-free survival (DFS; P = 0.0006). Other factors associated with shortened DFS and DSS by univariate analysis were high tumor grade, nodal metastases, and large tumor size (P < 0.0001 for each). Multivariate analysis of data for all of the patients demonstrated that tumor size, nodal status, ER, histological grade, and erbB-2 showed independent prognostic value. In node-negative patients, tumor size and mitotic rate per 1000 cells independently predicted DFS (P = 0.0055). Tumor grade was the only independent predictor of DSS. For node-positive patients, tumor size, nodal status, ER, and erbB-2 were independent prognostic factors. The number of mitoses per 1000 was independently associated with DFS (P = 0.043) but not with DSS. Apoptosis data did not provide independent prognostic value in any, node-positive or node-negative, breast cancer patients.

Cyclooxygenase-2 expression in human gliomas: prognostic significance and molecular correlations

Cyclooxygenase (COX)-2, the inducible isoform of prostaglandin H synthase, has been implicated in the growth and progression of a variety of human cancers. Although COX-2 overexpression has been observed in human gliomas, the prognostic or clinical relevance of this overexpression has not been investigated to date. In addition, no study has analyzed the relationship between COX-2 expression and other molecular alterations in gliomas. Consequently, we examined COX-2 expression by immunohistochemistry in tumor specimens from 66 patients with low- and high-grade astrocytomas and correlated the percentage of COX-2 expression with patient survival. We also analyzed the relative importance of COX-2 expression in comparison with other clinicopathological features (age and tumor grade) and other molecular alterations commonly found in gliomas (high MIB-1 level, p53 alteration, loss of retinoblastoma (Rb) protein or p16, and high bcl-2 level). Kaplan-Meier analyses demonstrated that high COX-2 expression (>50% of cells stained positive) correlated with poor survival for the study group as a whole (P < 0.0001) and for those with glioblastoma multiforme in particular (P < 0.03). Cox regression analyses demonstrated that COX-2 expression was the strongest predictor of outcome, independent of all other variables. In addition, high COX-2 expression correlated with increasing histological grade but did not correlate with positive p53 immunostaining, bcl-2 expression, loss of p16 or retinoblastoma protein expression, or high MIB-1 expression. These findings indicate that high COX-2 expression in tumor cells is associated with clinically more aggressive gliomas and is a strong predictor of poor survival.

Adenovirus-mediated transfer of p53 augments hyperthermia-induced apoptosis in U251 glioma cells

PURPOSE

Hyperthermia kills glioma cells by inducing apoptosis and is thereby an effective therapeutic modality for the treatment of malignant gliomas. However, cells harboring mutated p53 are refractory to hyperthermia-induced apoptosis. In this study, we assessed whether or not adenovirus (Adv)-mediated transduction of p53 overrides this resistant mechanism.

METHODS AND MATERIALS

We transduced the p53 wild-type tumor suppressor gene into U251 glioma cells harboring mutated p53 using Adv vectors in combination with hyperthermia (43, 44.5 degrees C), and evaluated the degree of cell death and apoptosis.

RESULTS

The percentage of cells that had died, as measured by trypan blue staining, among U251 cells infected with the Adv for p53 (Adv-p53) and treated with hyperthermia, was significantly higher than the percentage of cells that had died among U251 cells infected with Adv-p53 and not treated with hyperthermia, or those infected with the control Adv for dE (Adv-dE) and treated with hyperthermia. The degree of apoptosis, measured at 24 h after treatment, in hyperthermia-treated U251 cells infected with Adv-p53 (43 degrees C, 73%; 44.5 degrees C, 92%) was much higher than that infected with Adv-p53 (41%), or that infected with control Adv-dE and treated with hyperthermia (43 degrees C, 1.3%; 44.5 degrees C, 19%). Treatment with combined hyperthermia and Adv-p53 infection induced cleavage of caspase-3 in U251 cells.

CONCLUSION

These results indicate that Adv-mediated transduction of p53 would render glioma cells highly sensitive to hyperthermia.

[The protein expression of p53 and bcl-2 in laryngeal squamous cell carcinoma]

OBJECTIVE

To detect the relationship of p53 and bcl-2 gene to laryngeal carcinoma.

METHODS

p53 and bcl-2 protein expressions were examined in the specimens of 60 laryngeal carcinomas and 8 vocal cord polyps by immunohistochemistry method.

RESULTS

Overexpressions of p53 and bcl-2 were found in the laryngeal carcinoma specimens; the positive rates of p53 and bcl-2 protein expression were 61.7%(37/60) and 43.3%(26/60), respectively. Negative results were observed in all the vocal cord polyp specimens. The positive rates of p53 and bcl-2 expression were related to the histological grade and cervical lymphatic metastasis of laryngeal carcinoma but not related to clinical stage and tumor types.

CONCLUSION

The results of this study support the hypothesis that p53 and bcl-2 gene may be involved in the apoptosis of laryngeal carcinoma and they may play an important role in the pathogenesis of laryngeal cancer.

p53 Displacement from Centrosomes and p53-mediated G1 Arrest following Transient Inhibition of the Mitotic Spindle

Growing evidence indicates a central role for p53 in mediating cell cycle arrest in response to mitotic spindle defects so as to prevent rereplication in cells in which the mitotic division has failed. Here we report that a transient inhibition of spindle assembly induced by nocodazole, a tubulin-depolymerizing drug, triggers a stable activation of p53, which can transduce a cell cycle inhibitory signal even when the spindle-damaging agent is removed and the spindle is allowed to reassemble. Cells transiently exposed to nocodazole continue to express high levels of p53 and p21 in the cell cycle that follows the transient exposure to nocodazole and become arrested in G(1), regardless of whether they carry a diploid or polyploid genome after mitotic exit. We also show that p53 normally associates with centrosomes in mitotic cells, whereas nocodazole disrupts this association. Together these results suggest that the induction of spindle damage, albeit transient, interferes with the subcellular localization of p53 at specific mitotic locations, which in turn dictates cell cycle arrest in the offspring of such defective mitoses.

Antisense Inhibition of BRCA1 Expression and Molecular Analysis of Hereditary Tumors Indicate That Functional Inactivation of the p53 DNA Damage Response Pathway Is Required for BRCA-Associated Tumorigenesis

OBJECTIVE

The purpose of this investigation was to test the hypothesis that mutation of TP53 is a requirement for BRCA-associated cancer development.

METHODS

A cell line experimentally deficient in BRCA1 protein was constructed using a regulatable antisense expression vector expressing 4000 bp from the BRCA1 cDNA. Changes in BRCA1, p53, and p21 protein levels were assayed by immunoblotting. Ovarian tumors with germline mutations in BRCA1 or BRCA2 were screened for mutations in TP53 by single-strand conformation polymorphism analysis.

RESULTS

Antisense inhibition of BRCA1 protein caused p53 and p21 protein levels to rise, indicating that partial loss of BRCA1 function activates the p53 DNA damage response pathway. Somatic mutation of TP53 was observed in 7 of 14 BRCA-associated ovarian tumors.

CONCLUSIONS

Our findings provide novel evidence that loss of BRCA1 function in human cells activates the p53 DNA damage response pathway and that loss of this pathway, by somatic mutation of TP53, is a likely requirement for BRCA-associated tumor development.

Angiogenesis and apoptosis-related protein (p53, bcl-2, and bax) expression versus response of gastric adenocarcinomas to paclitaxel and carboplatin chemotherapy

The role of angiogenesis and apoptosis-related proteins in defining response to chemotherapy is poorly understood. We examined the microvessel density (MVD) and the expression of p53, bcl-2, and bax proteins in a series of 28 locally advanced gastric adenocarcinomas, treated with paclitaxel and carboplatin. A strong cytoplasmic reactivity in more than 10% of cancer cells was recorded in 25% of cases for p53 protein, and in 14% and 64% of cases for bcl-2 and bax proteins, respectively. Microvessel density was assigned in three categories: low (<35), medium (35-60), and high (>60). Tumors of medium MVD showed a significantly higher response rate compared with those of high or low MVD (p = 0.01 and 0.001, respectively), and prognosis was significantly better in this group of patients with medium MVD tumors (p < 0.02). Loss of bax protein expression was somewhat more frequent in tumors resistant to chemotherapy, but this difference was not of statistical significance. Nuclear p53 reactivity was associated with higher MVD (p = 0.02). The expression of p53 and bcl-2 did not influence the outcome of treatment. The present study suggests that although apoptosis-related proteins may have a role in defining response to taxanes, parameters related to tumors' vasculature, such as drug availability or angiogenic tissue regeneration, may be equally important.

Widespread expression of thioredoxin and thioredoxin reductase in non-small cell lung carcinoma

We investigated the expression of thioredoxin (Trx) and thioredoxin reductase (TrxR) in 89 non-small cell lung carcinomas. Additionally, immortalized human bronchial epithelial cells (BEAS 2B) and four human lung carcinoma cells lines (A549, SK-MES-1, CALU-6, and A427) were studied by Western blot and reverse transcription-PCR for the synthesis of Trx and TrxR protein and mRNA expression in vitro. The histological samples were also studied for immunohistochemical p53 and proliferating cell nuclear antigen expression and apoptosis. In non-neoplastic lung, Trx and TrxR expression was seen in bronchial epithelial cells and alveolar macrophages, metaplastic alveolar epithelial cells, and chondrocytes of the bronchus. In non-small cell lung carcinomas, there was a widespread expression of Trx and TrxR with only three and eight cases negative, respectively. Trx and TrxR expression was located in both cytoplasmic and nuclear compartments of the cells. There was a statistical association between cytoplasmic and nuclear Trx or TrxR expression. Grade I-II tumors showed stronger cytoplasmic and nuclear Trx and TrxR immunoreactivity than grade III tumors. No association was found between p53 and proliferating cell nuclear antigen expression and Trx or TrxR immunoreactivity. However, apoptosis was inversely associated with nuclear Trx and TrxR positivity. In the cell lines studied, both non-neoplastic BEAS 2B cells and all of the carcinoma cell lines expressed Trx and TrxR proteins and mRNA. The results show that these redox-regulating proteins are highly expressed in lung carcinomas taking part in activation of transcriptional factors and regulation of apoptosis in non-small cell lung carcinoma. In high-grade tumors, Trx and TrxR expression is diminished, suggesting loss of redox regulation in tumors with low differentiation.

[Expression of surviving gene and its relationship with expression of P53, c-myc, k-ras proteins in non-small-cell lung cancer]

OBJECTIVE

To study the expression of surviving and its relationship with expression of P53, c-myc, k-ras in non-small-cell lung cancer (NSCLC).

METHODS

Expression of the surviving mRNA was evaluated by reverse transcriptase polymerase chain reaction (RT-PCR) in 76 NSCLC tumor samples, 20 benign phymatoid lesion and 21 adjacent normal lung tissue samples. Immunohistochemical assay was to detect the expression of P53, c-myc, k-ras proteins.

RESULTS

Expression of surviving gene was detected in a significantly greater proportion of NSCLC (61%) than phymatoid lesion (30%) and adjacent normal lung tissue (19%) (P < 0.001). There was no relationship between surviving gene expression and histologic subtype, differentiation, TNM stages, or lymph node metastases. The expression of surviving gene correlated with P53 or c-myc expression, but not k-ras expression.

CONCLUSION

(1) The up-regulation expression of surviving gene in NSCLC suggested that surviving may play a role in the pathway of carcinogenesis and surviving may be identified as a potential therapeutic target in NSCLC. (2) surviving, de-activation of antioncogene P53 and up-regulation of oncogene c-myc might play synergetic roles in the process of carcinogenesis of NSCLC. But surviving and k-ras may be independently involved in the pathogenesis of lung cancer.

Relevance of the rates of PCNA, Ki-67 and p53 expression according to the epithelial compartment in cervical lesions

In order to assess further biological evidence for similarities among the "diagnostic classes" of cervical lesions, which are now a matter of international discussion in the search for a uniform classification, the purpose of this study was to characterize the immunoexpression of cell proliferation markers (proliferating cell nuclear antigen, PCNA and Ki-67) and protein p53. Each marker was individually quantified in basal, intermediate, and superficial epithelial compartments presenting chronic cervicitis (CC) accompanied by the cytopathic effects of infection by human papillomavirus (CCHPV) or not (CC), as well as in cervical intraepithelial neoplasia (CIN) grades I, II, and III. A total of 100 patients were evaluated and the positive nuclei were counted separately, including all extensions of the available epithelium. The percentage of PCNA- and Ki-67-positive cells increased with increasing grade of the cervical lesions, although PCNA immunoreactivity was always greater than the immunoreactivity observed with Ki-67 antigen. The immunoexpression of p53 protein was found to be weak, with no remarkable behavior in any specific "diagnostic class". The differences in cell proliferation markers found herein further emphasize the progressive loss of epithelial layer organization in the course of the development of preneoplastic changes in cervical squamous epithelium. Furthermore, difficulties in morphologically distinguishing "borderline lesions" persist when cell cycle markers are studied, further supporting the suggestion to consider the lesions of CCHPV and CIN I together as only one diagnostic class. Conversely, the different immune profile found between CIN II and III further supports the validity of the subdivision of CIN into three groups.

[Treatment of lymph node metastasis from the viewpoint of surgical oncology]

We have investigated methods to predict lymph node metastasis in early gastric cancer. First, the efficacy of fluorescence in situ hybridization (FISH) using the dual-color method was evaluated as a potential marker of lymph node metastasis in 20 early gastric cancers. A significant increase in the fraction of cells with a decrease in p53 was observed in early gastric cancer compared with normal tissues. More importantly, a significant increase in the fraction of cells with p53 deletion was observed in patients with lymph node metastasis. The predictive accuracy was 45%. Second, the relationship between the degree of expression of biological markers and lymph node metastasis was examined. High expression of p27 and cyclin E had a strong correlation with lymph node metastasis. Moreover, all patients with combined high expression of p27, cyclin E, and matrix metalloproteinase-9 had lymph node metastasis. However, these represented only 21% of cases with lymph node metastasis. Difficulty in the clinical use of these biological markers to detect lymph node metastasis depends on the feedback mechanism of cell cycle regulators or heterogeneity of the lesion. These problems should be resolved in the near feature.

ATM protein expression correlates with radioresistance in primary glioblastoma cells in culture

PURPOSE

Glioblastoma multiforme (GBM) is one of the malignancies most resistant to radiation therapy. In contrast, cells derived from individuals with ataxia telangiectasia (AT), possessing mutations in the ATM gene, demonstrate increased sensitivity to ionizing radiation. Using a collection of glioma specimens adapted to tissue culture and several established GBM cell lines, we investigated the relationship between ATM protein expression and radiosensitivity. The three aims of our study were to: (1) quantify ATM protein levels in cultured glioma cells; (2) measure the correlation between ATM protein levels and radiation sensitivity; and (3) examine the dependence of ATM on p53 status.

METHODS AND MATERIALS

Glioma specimens were collected, catalogued, and adapted to grow in culture. Levels of ATM, p53, and p21 proteins were determined by Western blot. Radiation sensitivities were determined by clonogenic assays. p53 mutation status was determined by DNA sequencing. Correlations were identified by linear regression analysis.

RESULTS

ATM protein levels were variable in the primary gliomas. Glioma cell lines demonstrated significantly lower levels of ATM protein. Clonogenic assays of cell strains and cell lines yielded survival fractions (SF2s) consistent with the radioresistant behavior of GBM tumors in vivo. Regression analysis revealed a high correlation between ATM protein levels and SF2 for primary glioma cell strains, but not for established GBM cell lines. p53 status failed to predict radiosensitivity.

CONCLUSION

We have demonstrated that while our collection of low passage cell cultures depends on ATM for their resistance to IR, established cell lines may acquire adaptive characteristics which downplay the role of the ATM gene product in vitro. Therefore, attenuating ATM gene expression may be a successful strategy in the treatment of GBM tumors.

p53 protein accumulation and genomic instability in head and neck multistep tumorigenesis

Head and neck cancer develops in a multistep process and is associated with increasing frequencies of p53 alterations and with increasing genomic instability. To study the relationship of p53 alterations and genomic instability during head and neck tumorigenesis, we analyzed p53 protein expression and chromosome 9 and 17 polysomy in 48 squamous cell carcinomas of the head and neck and their adjacent normal epithelium (31 sites), hyperplastic (24 sites), and dysplastic lesions (26 sites). Normal oral epithelium obtained from seven nonsmoking, cancer-free individuals served as negative controls. Six (19%) of 31 lesions in adjacent normal epithelium, 7 (29%) of 24 hyperplastic lesions, 12 (46%) of 26 dysplastic lesions, and 28 (58%) of 48 squamous cell carcinomas expressed p53. In contrast, no normal control epithelium had detectable p53 expression. To determine the relationship between dysregulated p53 expression and genomic instability during tumorigenesis, we compared p53 immunohistochemistry distributions and chromosome polysomy levels (by chromosome in situ hybridization) in different histological groups associated with tissue progression. Although the degree of chromosome polysomy increased for all of the groups during histological progression, lesions with dysregulated p53 expression showed nearly 2-4-fold increased levels of chromosome polysomy. This trend was significant for dysplastic lesions (P = 0.005 and P = 0.002 for chromosomes 9 and 17, respectively) and for squamous cell carcinoma (P = 0.005 and P = 0.002 for chromosomes 9 and 17, respectively). Image analysis studies for 28 p53-expressing tumors and their adjacent premalignant lesions demonstrated a strong spatial correlation between stepwise transitions from low to high p53 expression and increased chromosome polysomy frequencies in 13 (46%) of 28 cases. These findings suggest that altered p53 expression is associated with increased genetic instability in preneoplastic epithelium and may play a driving force for increasing the rate of accumulation of genetic events during head and neck tumorigenesis.

Frequent p53 mutation in brain (fetal)-type glycogen phosphorylase positive foci adjacent to human 'de novo' colorectal carcinomas

'de novo' carcinogenesis has been advocated besides 'adenoma carcinoma sequence' as another dominant pathway leading to colorectal carcinoma. Our recent study has demonstrated that the distribution of brain (fetal)-type glycogen phosphorylase (BGP) positive foci (BGP foci) has a close relationship with the location of 'de novo' carcinoma. The aims of the present study are to investigate genetic alteration in the BGP foci and to characterize them in the 'de novo' carcinogenesis. 17 colorectal carcinomas without any adenoma component expressing both immunoreactive p53 and BGP protein were selected from 96 resected specimens from our previous study. Further investigations to examine the proliferating cell nuclear antigen (PCNA)-labelling index, and the p53 and the codon 12 of K-ras mutation using the polymerase chain reaction-single strand conformation polymorphism were performed in the BGP foci, BGP negative mucosa and carcinoma. The BGP foci were observed sporadically in the transitional mucosa adjacent to the carcinoma in all cases. The PCNA labelling index in the BGP foci was significantly higher than that in the BGP negative mucosa (P< 0.001). p53 mutations were observed in 8 carcinomas, but no K-ras mutation was detected. Interestingly, although none of the overexpressions of p53 protein was detected immunohistochemically in the BGP positive foci, the p53 gene frequently (41.2% of the BGP foci tested) mutated in spite of no K-ras mutation. The present study demonstrates potentially premalignant foci in the colorectal transitional mucosa with frequent p53 gene mutation. It is suggested that BGP foci are promising candidates for the further investigation of 'de novo' colorectal carcinogenesis.

Isolated late local recurrences with high mitotic count and early local recurrences following breast-conserving therapy are associated with increased risk on distant metastasis

PURPOSE

Local recurrence (LR) after breast-conserving therapy (BCT) is associated with an increased risk for the development of distant metastasis. We studied risk factors for distant metastasis risk (DMR) and poor prognosis within a group of patients with LR as first event.

PATIENTS AND METHODS

From a cohort of 1481 breast carcinomas treated with BCT in the period 1980-1994, a total of 68 pT1-3 N0-1 patients developed LR as first event. We have studied risk factors for the development of distant metastasis within this group of patients with LR. In addition to clinical factors (age at BCT and LR, mode of detection, location of LR, and treatment of LR), the histology slides of the primary and the recurrent tumor were reviewed. Immunohistochemical staining was performed for the following proteins: bcl-2, cyclin D1, E-cadherin, EGF receptor, ER, PR, Ki-67, c-erbB-2/neu, and p53. Statistical analyses were performed using conditional logistic regression.

RESULTS

At a median follow-up after LR of 5.6 years, the 5-year DMR was 53%. In univariate analysis, none of the factors of the primary tumor was found to be associated with DMR after LR. Of the recurrent tumor the following factors were found to be risk factors for high DMR after LR: interval between treatment of the primary tumor and LR at 2 years or less (relative risk, 2.38; 95% confidence interval, 1.22-4.76; p = 0.008) and high mitotic count (relative risk, 2.51; 95% confidence interval, 1.03-6.15; p = 0.04). All patients with noninvasive recurrent tumor were alive at the time of analysis. Patients with an interval of greater than 2 years and a recurrent tumor with high mitotic count were found to have an equally poor prognosis compared to patients with LRs detected after a short interval.

CONCLUSION

LR after BCT is associated with higher DMR and poor prognosis. Patients with LR within 2 years after BCT are especially at high risk. Late recurrences with high mitotic count have the same poor prognosis as early recurrences. For these patients, systemic treatment at time of the detection of LR should be considered.

Inhibition of 6-hydroxydopamine-induced p53 expression and survival of neuroblastoma cells following interaction with astrocytes

The neurotoxin 6-hydroxydopamine has been used to induce selective dopaminergic cell death in animal models of Parkinson's disease. The response of neurons to this toxin has been shown to be greatly influenced by astrocytes. Our laboratory reported previously that human neuroblastoma SH-SY5Y cells became more resistant to the toxicity of 6-hydroxydopamine when co-cultured with mouse astrocytes. This enhanced tolerance required direct and specific adhesion between SH-SY5Y cells and astrocytes. We hypothesized that this interaction led to biochemical changes in SH-SY5Y cells, thereby protecting these cells from toxicity. To study these changes, we again co-cultured SH-SY5Y cells with astrocytes and treated them with 6-hydroxydopamine. An optimized condition of trypsin treatment was employed to separate SH-SY5Y cells from astrocytes quickly. Western blot analysis demonstrated that 6-hydroxydopamine significantly increased p53 protein in monolayer SH-SY5Y cells grown in either regular medium or conditioned medium from astrocytes. This change, however, was not observed in the group co-cultured with astrocytes. Data obtained from the ribonuclease protection assay indicated that similar changes also occurred at the transcriptional level. The enhanced resistance of the co-cultured SH-SY5Y cells to the toxicity of 6-hydroxydopamine is attributed to the ability of astrocytes to prevent the increase of p53 induced by this toxin. This study demonstrates the significance of the interaction between astrocytes and neurons when they are exposed to neurotoxins.

Coexpression of Mutant p53 and p193 Renders Embryonic Stem Cell–Derived Cardiomyocytes Responsive to the Growth-Promoting Activities of Adenoviral E1A

Abstract —Expression of adenoviral E1A in cardiomyocytes results in the activation of DNA synthesis followed by apoptosis. In contrast, expression of simian virus 40 large T antigen induces sustained cardiomyocyte proliferation. Previous studies have shown that T antigen binds to 2 proapoptotic proteins in cardiomyocytes, namely the p53 tumor suppressor and p193 (a new member of the BH3-only proapoptosis subfamily). Structure-function analyses identified a p193 C-terminal truncation mutant that encodes prosurvival activity. This mutant was used to test the role of p193 in E1A-induced cardiomyocyte apoptosis. E1A induced apoptosis in cardiomyocytes derived from differentiating embryonic stem cells. Expression of the prosurvival p193 mutant alone or a mutant p53 alone did not block E1A-induced apoptosis. In contrast, combinatorial expression of mutant p193 and mutant p53 blocked E1A-induced apoptosis, resulting in a proliferative response indistinguishable from that seen with T antigen. These results confirm the hypothesis that there are 2 proapoptotic pathways, encoded by p53 and p193, respectively, which restrict cardiomyocyte cell cycle activity in differentiating embryonic stem cell cultures. Furthermore, these results explain in molecular terms the phenotypic differences of E1A versus T-antigen gene transfer in cardiomyocytes.

Inactivation of p53 sensitizes U87MG glioma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea

We examined the effect of p53 inactivation on the response of U87MG glioma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). These studies were motivated by three observations: (a) some human astrocytomas are sensitive to BCNU and some are resistant; (b) chemosensitive astrocytomas are more likely to be found in young adults whose tumors are more likely to harbor a p53 mutation; and (c) mouse astrocytes lacking the p53 gene are more sensitive to BCNU than wild-type cells. Here, we observed that p53 inactivation by transfection with pCMV-E6 sensitized U87MG cells to BCNU. Compared with control U87MG-neo cells with intact p53 function, the clonogenic survival of U87MG-E6 cells exposed to BCNU was reduced significantly. In U87MG-E6 cells, sensitization to BCNU was associated with failure of p21(WAF1) induction, transient cell cycle arrest in S phase, accumulation of polyploid cells, and significant cell death. In contrast, resistance to BCNU in U87MG-neo cells was associated with up-regulation of p53, prolonged induction of p21(WAF1), sustained cell cycle arrest in S phase, and enhancement of DNA repair. U87MG cells with disrupted p53 function were less able to repair BCNU-induced DNA damage and survive this chemotherapeutic insult. The question arises of whether p53 dysfunction might be a chemosensitizing genetic alteration in human astrocytic gliomas.

Detection of JC virus DNA sequences and expression of the viral regulatory protein T-antigen in tumors of the central nervous system

JC virus (JCV) is a neurotropic polyomavirus infecting greater than 70% of the human population worldwide during early childhood. Replication of JCV in brains of individuals with impaired immune systems results in the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). Furthermore, JCV possesses an oncogenic potential and induces development of various neuroectodermal origin tumors including medulloblastomas and glioblastomas in experimental animals. The oncogenecity of JCV is attributed to the viral early gene product, T-antigen, which has the ability to associate with and functionally inactivate well-studied tumor suppressor proteins including p53 and pRB: The observations from laboratory animal experiments have provided a rationale for examining the presence of the JCV DNA sequence and expression of the viral oncogenic protein in human brain tumors. We have examined 85 clinical specimens from the United Kingdom, Greece, and the United States, representing various human brain tumors including oligodendroglioma, astrocytoma, pilocytic astrocytoma, oligoastrocytoma, anaplastic astrocytoma, anaplastic oligodendroglioma, glioblastoma multiforme, gliomatosis cerebri, gliosarcoma, ependymoma, and subependymoma, for their possible association with JCV. We performed gene amplification techniques using a pair of primers that recognize the JCV DNA sequence, and we demonstrated the presence of the viral early sequence in 49 (69%) of 71 samples. More importantly, our results from immunohistochemistry analysis revealed expression of JCV T-antigen in the nuclei of tumor cells in 28 (32.9%) of 85 tested samples. These observations, along with earlier in vitro and in vivo data on the transforming ability of this human neurotropic virus invite additional studies to re-evaluate the role of JCV in the pathogenesis of human brain tumors.

Alterations in p53 and E2F-1 function common to immortalized chicken embryo fibroblasts

A number of non-virally and non-chemically immortalized chicken embryo fibroblast (CEF) cells have been established recently in continuous cell culture. All immortal CEF cells tested showed common genetic alterations in the expression patterns of p53 and E2F-1 mRNA and protein which were down- and up-regulated, respectively. The biological effects of differentially regulated p53 and E2F-1 were determined by reporter gene transcriptional activity assays, DNA binding assays, and Northern blot analysis of the expression patterns of down-stream genes. In addition, expression of most of the cyclin genes was up-regulated in immortal CEF cells, which may be associated with the rapid cell division rates and serum-independent growth patterns seen in immortal CEF cells. The telomeric lengths and chromosome integrity were maintained in all immortal CEF cell lines without detectable telomerase activity. Although the functional inactivations of the p53 and Rb regulatory pathways are known to be common events for cellular immortalization, the genetic changes leading to alteration of p53 and E2F-1 function through transcriptional and post-transcriptional regulation seem to be unique in immortal CEF cells.

Characterization of germline TP53 splicing mutations and their genetic and functional analysis

Germline TP53 splicing mutations have been described infrequently (>2%) in the literature, however in a series of 40 patients and families identified by our group in which there are germline TP53 mutations, seven affect splicing (18%). The low figure reported in the literature might reflect the method of mutation detection, which in many studies does not include all splice junctions. These data indicate that a significant proportion of TP53 germline mutations are currently unrecognized. We have carried out detailed studies of the effects of the different mutations on splicing, and see distinct variations in the effects of the same mutation in different patients. Furthermore we have identified the usage of a non-consensus splice donor site in four families with an intron 4 splice donor mutation.

[The role of estrogen receptor, vitamin D receptor and calcium receptor genotypes in the pathogenesis of colorectal cancer]

In this study, the Xbal polymorphisms of the estrogen-, the Bsml polymorphism of the vitamin D- as well as the A986S polymorphism of the calcium-sensing receptor genes were investigated in 56 patients with colorectal cancer. The expression of erbB-2, epidermal growth factor receptor, ras, p53 and their relationship to estrogen-, vitamin D- and calcium-sensing receptor genotypes were also studied. In subjects exhibiting XX genotype of the estrogen receptor gene or bb genotype of the vitamin D receptor gene, erbB-2 expression was significantly lower compared to those with xx, Xx or BB, Bb (6/56 and 11/56 vs. 31/56 and 26/56; p = 0.0043 and 0.041). The presence of the XX alleles of estrogen receptor gene significantly correlated with the overexpression of the epidermal growth factor receptor expression in tumors, whereas in xx and Xx genotypes, significantly higher expression was seen (7/56 vs. 30/56; p = 0.049). Analyzing the combinations of the two gene allelic variants, we have found XXbb genotype to be associated with a significantly lower erbB-2 expression, compared to other combinations (Xxbb, XxBb, XXBb) (2/7 vs. 7/7, 4/5, 4/5; p = 0.0011). Patients with AA calcium-sensing receptor genotype were in higher UICC stages at the time of discovery of their disease than those with AS genotype. The AA allelic variant of the calcium-sensing gene was more frequent among patients with colorectal cancer compared to controls (36/56 vs. 36/112; p = 0.0004). Our observations raise the possibility that estrogen-, and vitamin D receptor gene polymorphisms accompanied with variable oncogene expression might influence the pathogenic processes resulting in the development of colorectal cancer. The A986S polymorphism of calcium-sensing receptor might also be a prognostic marker of the disease.