Polysomy of chromosome 7 is associated with amplification and overexpression of the EGF-receptor gene in a human carcinoma cell line derived from a brain metastasis

Radiolabeling of epidermal growth factor with 99mTc and in vivo localization following intracerebral injection into normal and glioma-bearing rats

High grade gliomas may have amplified expression of the epidermal growth factor receptor (EGFR) gene c-erb-B, which often is associated with increased expression of transmembrane EGFR. The purpose of the present study was to develop a method for labeling EGF with 99mTc and to determine whether the resulting radioligand would localize, following intracerebral injection, in rats bearing EGFR-positive gliomas. EGF has a relatively low molecular mass (approximately 6 kDa) compared to monoclonal antibodies, and this has allowed smaller bioconjugates, which should diffuse more rapidly within the brain and more effectively target disseminated glioma cells, to be constructed. In the present study, EGF has been labeled with either 131I or 99mTc, and in vitro uptake of the resulting radioligand has been investigated using C6EGFR rat glioma cells, which had been transfected with the EGFR gene. Cellular uptake of 131I radioactivity peaked after approximately 30 min of incubation with [131I]EGF, following which time it declined, while 99mTc radioactivity continued to increase over a 6 h incubation with [99mTc]-EGF. To determine if radiolabeled EGF had in vivo tumor-localizing properties, C6EGFR glioma cells were implanted stereotactically into the brains of Fischer rats. Four weeks later, either 99mTc- or 131I-labeled EGF was injected intracerebrally into normal or glioma-bearing animals using the same stereotactic coordinates. External gamma scintigraphy revealed that 131I radioactivity disappeared rapidly from the brain regions of tumor-bearing animals compared to 99mTc, approximately 50% of which remained in the tumor for up to 12 h. In contrast, only approximately 20% remained in the brains of non-tumor-bearing animals after 6 h. These studies are the first to describe a method for radiolabeling EGF with 99mTc and to detect it by external scintigraphy in the brains of tumor-bearing animals.

Interphase cytogenetics of prostate cancer: fluorescence in situ hybridisation (FISH) analysis of Japanese cases

No numerical aberration of chromosomes that might be specific for prostate cancer has so far been established. We used fluorescence in situ hybridisation (FISH) with centromere-specific probes for chromosomes 7, 8, 17, X and Y to establish the distribution of centromere copy numbers in frozen-stored or freshly prepared samples of benign prostate hypertrophy (BPH) and to detect numerical aberrations of these chromosomes in 28 prostate cancers from Japanese men. There was no significant difference in the data of centromere copy numbers between fresh and frozen-stored tissue. The most common aberration in prostate cancers was a gain of chromosome 8 (57%), with numerical aberration of chromosome 7 being the second most frequent anomaly (50%). Numerical aberration of chromosome 7 is most significantly associated with a higher Gleason score (GS) (P < 0.005) or with lymph node metastasis (P < 0.001). Numerical aberration of several chromosomes, including chromosomes 7 and/or 8, was common in aggressive prostate cancers. Loss of chromosome Y was detected in only 4% of cases. FISH analysis thus proved to be a useful method for detecting numerical aberrations of individual chromosomes, with application to touch preparations of frozen-stored tissue having the advantage of exact sampling of cancer foci. The results suggest that numerical aberration of chromosome 7 is associated with aggressive tumour behaviour and poor prognosis of patients with prostate cancer. The association between genetic change and chromosomal abnormality should be studied in detail.

ADP-ribosylation of the G protein Rho inhibits integrin regulation of tumor cell growth

Using a gastric derived tumor line, we investigated the involvement of beta 1 integrin and Rho in cell growth regulation in response to collagen. The addition of C3 exoenzyme from clostridium botulinum to specifically ribosylate and inhibit the function of the rho gene products inhibited cellular proliferation in a dose-dependent fashion. C3 exoenzyme exhibited broad cytostatic activity toward a number of tumor lines and induced G0/G1 accumulation, cyclin A inhibition, and pronounced alterations in cell morphology. Integrin-mediated adhesion to collagen led to the expression of the cyclin A gene whose expression could be blocked using anti-beta 1 integrin monoclonal antibodies. Phospholipid levels were induced upon beta 1 integrin-mediated adhesion to collagen, and the phospholipid induction was inhibited by either antibodies to beta 1 integrin or pretreatment of cells with C3 exoenzyme. Significant reduction in phospholipid levels correlated with proliferation for a panel of tumor lines deprived of adhesion to substrate. These results implicate a novel role for integrins and Rho in the regulation of tumour growth in response to matrix.

Integrin-mediated entry into S phase of human gastric adenocarcinoma cells

The integrins are a family of integral membrane receptors that participate in binding to various extracellular and cell surface proteins during adhesion, migration, and homing of normal and neoplastic cells. In this study, we characterized the involvement of integrins in mediating the growth of an adhesion-dependent gastric adenocarcinoma line, ST2. This line was distinguished and selected for study based on its inability to grow when suspended in soft agar or plated on poly(2-hydroxyethyl methacrylate)-coated dishes. ST2 cells arrested in G0/G1 of the cell cycle when deprived of adhesion to substrate. Using purified matrix components, collagen was found to be highly active in promoting beta 1 integrin-mediated cell attachment and spreading. Subsequent to spreading on collagen, the cells were released from G0/G1 block and progressed into S phase. Monoclonal antibodies to alpha 2 or beta 1 integrin blocked the reinduction of both cell spreading and entry into S phase. These studies suggest that during the metastatic process, integrin receptor interaction with the insoluble matrix may be an important step leading to proliferation of some tumors.

Numerical abnormalities of chromosome 7 in human prostate cancer detected by fluorescence in situ hybridization (FISH) on paraffin-embedded tissue sections with centromere-specific DNA probes

Fluorescence in situ hybridization (FISH) using chromosome-specific alpha-satellite DNA probes for chromosomes 7, 8, and 12 was performed on paraffin-embedded tissue sections and touch imprint preparations of 53 cases of human prostate cancer. Subsequent haematoxylin and eosin (H & E) staining of the hybridized tissue sections allowed unambiguous assignment of hybridization signals either to tumour or to non-tumorous parenchyma. Fifty-three cases of human prostate cancer were evaluated for numerical aberrations of chromosome 7. Scoring 200 cells of tumour and non-tumorous parenchyma in each case revealed abnormalities exclusively in tumour parenchyma in 41 cases (77 per cent). Ten of 41 cases (24 per cent) showed trisomy 7, and 15 cases (37 per cent) monosomy 7 or trisomy 7 in combination with monosomy 7, respectively. Sixteen cases (39 per cent) exhibited polysomy 7 in cells of the tumour parenchyma. In the tumour tissue in one case, different polyploid clones (triploid, tetraploid) and polysomy 7 could be identified by double hybridization with chromosome-specific DNA probes for chromosome 7, plus 8 or 12. The indicated numerical aberrations of chromosome 7 were correlated with 78 per cent of advanced pathological stages or poorly differentiated tumours (pT3/4 or G3) of prostate carcinomas. A statistical analysis of the data revealed significant relationships of particular numerical abnormalities of chromosome 7 to different pathological categories (pT, G, pN) of tumour classification. For the T-classification, the frequency of cells carrying polysomy 7 and polysomy 7/+7 increases significantly from pT1 to pT3/4 (P = 0.022).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical follow-up in 24 nonfamilial renal tumors cytogenetically characterized in tissue culture

OBJECTIVE

This study investigates the relationship between clonal chromosomal abnormalities detected in nonfamilial renal cell carcinoma and the clinical outcome, specifically, whether or not patients whose tumors had karyotypic changes have a different prognosis than those whose tumors did not.

METHOD

Fresh tumor tissue obtained from 32 cases was grown in tissue culture. Twenty four grew successfully and were harvested and multiple cells of each karyotyped. Clinical follow-up was obtained for at least five years or until the time of death.

RESULTS

Fourteen of 24 cases demonstrated karyotypic abnormalities including loss of Y chromosome (64%), trisomy 7 (50%), trisomy 12 (14%), trisomy 9, 10, 14, 15, 16, and 17, monosomy 9 and 20, and long-arm deletion of chromosome 16 (1 case each). Tumors were well-differentiated in 16 cases, moderately differentiated in 5 cases, and poorly differentiated in 1 case; 13 cases were pathologic Stage I, 5 Stage II, and 6 Stage III. Thirty-three percent of the patients demonstrated clinical progression.

CONCLUSIONS

No significant difference in prognosis could be found between patients with and without karyotypic abnormalities. The only clinical or pathologic difference which could be established was sex distribution. Significantly greater numbers of males had karyotypic abnormalities than females, but this could be explained by the high number of Y chromosome deletions that were detected. The lack of correlation between karyotypic abnormalities and clinical outcome may reflect a confounding factor in genetic evolution such that clinically determining chromosomal changes present early in a tumor's growth in vivo may no longer be present when the tumor is diagnosed, treated, or after it is grown in culture. This may make demonstration of such clinically significant chromosomal changes very difficult.

Relationships between Ki-67 labelling index, amplification of the epidermal growth factor receptor gene, and prognosis in human glioblastomas

The aim of this study was to determine possible relationships between Ki-67 labelling index (Ki-67 LI), amplification of the epidermal growth factor receptor (EGFR) gene, and prognosis in human glioblastomas. Ki-67 LI was determined on cryosections of biopsy specimens of 20 human glioblastomas with a mouse anti-human Ki-67 monoclonal antibody. Amplification of the EGFR gene was determined by slot blot and Southern blot analyses of DNA extracted from the tumour biopsies. The Ki-67 LI was higher in the glioblastoma group with EGFR gene amplification (8 tumours, median value of Ki-67 LI 4.2, range 0.4-24.6) than in those without EGFR gene amplification (12 tumours, median value of Ki-67 LI 0.8, range 0.2-11.8) (0.05 p less than 0.1). The glioblastoma patients with Ki-67 LI greater than 1.5 (10 tumours) had a statistically significant shorter survival than those with Ki-67 LI less than 1.5 (10 tumours) (p less than 0.05). The glioblastoma patients with EGFR gene amplification lived shorter time than those without EGFR gene amplification (p greater than 0.05).

Expression of the epidermal growth factor receptor gene in human brain metastases

Biopsy specimens of human brain metastases were examined for amplification and expression of the proto-oncogene c-erbB1 (located on chromosome 7) encoding the epidermal growth factor receptor (EGFR). Moreover, the tumour DNA was also examined for amplification of other cancer-related genes on this chromosome: the proto-oncogene c-met, the gene for platelet-derived growth factor A-chain, and the gene for plasminogen activator inhibitory type 1. All 18 brain metastases demonstrated positive binding of biotinylated EGF on cryosections. Three out of 18 metastases had amplification of the EGFR gene; the other chromosome-7 genes tested were not amplified. Thus, an increased EGFR gene expression seems to be a general finding in a wide range of carcinomas metastatic to the brain, whereas we found only occasional selective EGFR gene amplifications in single cases.

Nuclear and DNA-binding proteins in human brain tumors

Nuclear proteins obtained from human brain tumor cell lines by differential salt extraction were subjected to high-resolution two-dimensional electrophoresis. Several hundred spots were detectable in the low salt (0.4 M NaCl) extract using silver staining. These patterns exhibited remarkable differences between the different cell lines we analyzed. A less complex pattern occurred when nuclei were subsequently treated with high salt (2.5 M NaCl/5 M urea). We compared the electropherograms from various human glioblastoma cell lines and found them very similar and even a high degree of similarity occurs between glioblastomas and other human tumor cell lines. Beside these more general observations we detected several proteins at least enriched in human glioblastomas which were totally absent in low grade astrocytomas and nonglial tumors. They could be separated from the bulk of nonspecific proteins by simple modifications of the isoelectric focusing conditions. From these results we conclude that nuclear proteins obtained by sequential salt extraction and separated by two-dimensional techniques may provide tumor specific proteins suitable for antibody production.