Cytogenetic instability with balanced chromosome changes in an SV40 transformed human uroepithelial cell line.

Cytogenetic analysis at the 15th, 34th, 50th, and 56th passages of an SV40 immortalized human uroepithelial cell line (SV-HUC-1) showed continuous chromosome change and marker formation. Throughout these passages the transformed cells maintained their epithelial morphology, were SV40 T antigen positive, did not shed infectious SV40 virus, and were repeatedly found to be nontumorigenic when innoculated into athymic nude mice. Each of the passages studied was characterized by extensive karyotypic changes due to formation, rearrangement, and disappearance of different markers. A marker involving chromosome 1 was stable at three of the passages studied, whereas markers involving the X chromosome changed at each passage studied. Because of the incorporation of several chromosomes or chromosome arms into markers, the karyotype was genetically balanced in the first passage studied, with no net loss or gain of chromosomal material despite a modal number of 44. In subsequent passages, despite continued instability and generation of new markers, there was a slight but additive loss of genomic balance which increased with time in culture. Since continued karyotypic rearrangements did not lead to tumorigenic conversion, it is probable that genetic instability coupled with selection for the most balanced genome may be important for the immortalization of this cell line.

Amplification in human breast cancer of a gene encoding a c-myc mRNA-binding protein.

The coding region determinant-binding protein (CRD-BP) binds in vitro to c-myc mRNA and is thought to stabilize the mRNA and increase c-Myc protein abundance. The CRD-BP gene has 15 exons and 14 introns, is single-copy, and is located on chromosome 11 in mice and 17 in humans, close to HER-2/neu. The CRD-BP gene is moderately amplified in 12 of 40 human breast cancers; it is highly amplified in 2 others (14.4 and 20 copies). Despite their proximity, CRD-BP and HER-2/neu genes can be amplified independently. Amplification of a gene that might up-regulate c-Myc abundance could accelerate breast cancer.

Cell culture of human colon adenomas and carcinomas.

Cell lines were established from colon adenomas, including tubular and villous polyps, primary adenocarcinomas, and metastases arising in patients with colon adenocarcinomas. The protocol for cultivating these diverse tissues includes primary cultivation of tissue explants on a type I collagen gel followed by nonenzymatic subculture of the epithelial outgrowth. All early passages were accomplished using low subculture ratios. Cultured cells elaborate morphological structures which are similar to features present in the tissues from which they were cultivated. Specifically, all structural features of colon epithelial cells were identified, including junction formation, prominent microvilli, and mucin secretion, in several cell lines. Five cell lines cultured from colonic neoplasms at different stages of cancer progression were selected for detailed characterization. Cells grown from two tubular polyps had normal human karyotypes. Cells from a villous polyp and all adenocarcinomas were aneuploid with stable marker chromosomes. The established cell lines exhibit distinct phenotypes based on growth characteristics in vitro and in athymic mice; and it is suggested that these cell lines represent useful models for studying the evolution of colon cancer from a benign to an aggressive cell type.

EJ/ras neoplastic transformation of simian virus 40-immortalized human uroepithelial cells: a rare event.

To determine if expression of mutant p21 ras could convert Simian Virus 40-immortalized human uroepithelial cell line (SV-HUC) to tumorigenicity, SV-HUC cells were transfected with pSV2-neo (a neomycin-resistant gene) or PREJ/ras (c-HA-ras-1 with the 12th codon mutation and neo). Seven independent G418-resistant clones (A----G) were isolated from each group (SV-HUC/ras and SV-HUC/neo). SV-HUC/ras clones were morphologically altered, while SV-HUC/neo clones retained a typical SV-HUC epithelial morphology. Electrophoretic analysis of immunoprecipitated ras proteins detected altered p21 ras protein in four of seven SV-HUC/ras clones at passage (P)2 and in five of seven clones at P12 posttransfection. The relative levels of ras p21 differed among the clones and appeared to increase with passage in culture. RNA and DNA dot blot analyses showed that clones with more abundant mutant p21 also had higher ras RNA levels and, in one case, increased ras gene copy number. No altered ras protein was detected in any SV-HUC/neo clones. ras- and neo-transfected clones were tested for tumorigenicity at P2 posttransfection and again at P12 by four s.c. inoculations each into athymic nude mice. None of 56 inoculations of SV-HUC/neo clones was tumorigenic. None of the SV-HUC/ras clones at P2 gave rise to tumors at all four injection sites. However, two ras-transfected clones, SV-HUC/ras-B and SV-HUC/ras-F, produced one tumor each. One clone, SV-HUC/ras-D which produced abundant mutant p21, was negative when inoculated at P2, but produced tumors in four of four sites when reinoculated after ten passages in vitro. All tumorigenic clones had detectable levels of mutant ras p21. However, the relative levels of altered p21 ras protein among the SV-HUC/ras clones did not directly predict their tumorigenic potential, as several nontumorigenic SV-HUC/ras clones had protein levels equal to or higher than the most tumorigenic clone (SV-HUC/ras-D at P12). Cell lines established from the tumor explants exhibited higher ras gene copy numbers, higher RNA levels, and more abundant p21 than was seen in the clones at the time of inoculation. Therefore, increases in ras protein abundance occurred during tumor formation in vivo, as well as during passage of cells in culture, and such cells apparently had a selective growth advantage. However, expression of abundant mutant ras protein was not in itself sufficient for neoplastic transformation of SV-HUC.(ABSTRACT TRUNCATED AT 400 WORDS)

Rare clonal karyotypic variants in primary cultures of human breast carcinoma cells.

Cytogenetic analyses were performed on 40 previously untreated primary human breast carcinomas, four untreated breast metastases, nine human breast fibroadenomas, and ten normal human mammary tissues, all in primary culture. The results revealed predominantly normal diploid cells with abnormal clones in two of 40 primary carcinomas and one of four metastases. 3p deletion [del(3)(p14-21)], similar to that associated with small cell lung cancer, was found in a primary tumor from a patient with bilateral breast cancer. In addition, a clone with t(1;4) was found in another primary breast carcinoma, while a t(1;5) clone was found in a metastatic tumor.

Establishment and characterization of human colorectal cancer cell lines.

A protocol for establishment of human colorectal carcinoma cell lines from fresh surgically removed tissues is described. Twelve human colorectal carcinoma cell lines were established from 6 of 18 primary cancers and four of four metastases. Cell lines from concurrent primary tumors and metastases were established from two individual patients. Two primary cancers gave rise to multiple cell lines with differing biological characteristics. Factors contributing to our success appear to be differential selection on the basis of substrate adherence and the timing of passage. The protocol avoids the use of feeder layers or passage through athymic mice. The established cell lines exhibit a range of karyotypes, morphologies, and growth characteristics.

Nonrandom chromosome losses in stepwise neoplastic transformation in vitro of human uroepithelial cells.

An in vitro/in vivo transformation system was used to study chromosome region losses in stepwise neoplastic transformation and progression of human uroepithelial cells. Complete cytogenetic analyses were done on 17 independent carcinomas derived using this system and showed that losses of chromosome regions on 3p (P = 0.0003), 6q (P = 0.01), and 18q (P = 0.0003) were nonrandom. The smallest common losses [i.e., 3(p13----pter), 6(q21----q23), and 18(q21.1----qter)] were in putative cancer suppressor gene regions. In addition, cumulative losses from a group of 10 chromosome arms (i.e., 1p, 1q, 3p, 5q, 6q, 9q, 11p, 13q, 17p, and 18q) frequently deleted in clinical carcinomas were very significant (P = 0.0005) compared to losses from all other arms. Loss of 3p and 18q both correlated with transformation to high grade carcinomas (P = 0.001 and P = 0.004, respectively). These data provide new evidence supporting hypotheses that chromosome regions 3(p13----pter) and 6(q21----q23) contain genes that suppress cancer development. These results also provide new data confirming the hypothesis that genetic loss(es) in the 18(q21.1----qter) region are associated with the development of high grade malignancies.

Methylation of the androgen receptor promoter CpG island is associated with loss of androgen receptor expression in prostate cancer cells.

Androgen-independent metastatic prostate cancer is characterized by a heterogeneous loss of androgen receptor (AR) expression among tumor cells. In this study, we evaluate DNA hypermethylation as a potential transcriptional regulatory mechanism in AR-negative prostate cancer cell lines. Nucleotide sequence analysis demonstrates an approximately 15-kb CpG island in the AR gene that encompasses the transcription start site and exon 1. Using Southern blotting with methylation-sensitive restriction enzymes and methylation-specific PCR, we find aberrant methylation in the AR expression-negative cell lines Du145, DuPro, TSU-PR1, and PPC1. Incomplete methylation in the AR CpG island is also seen in normal female breast and ovarian tissues consistent with the inactivation of one X chromosome by hypermethylation. In contrast, prostate cancer cell lines LNCaP and PC3 express AR and are unmethylated. Normal prostate epithelial cell strains demonstrate no methylation. Exposure of AR-negative prostate cancer cell lines to 5-aza-2' deoxycytidine, a demethylating agent, induces the reexpression of AR RNA in DuPro and TSU-PR1. This reexpression is associated with a demethylation of this region. Prostate-specific antigen, an androgen-responsive gene, is also specifically induced in these lines after AR reexpression. Therefore, in vitro DNA methylation of the 5' CpG AR island may be associated with the loss of AR expression. Furthermore, our results demonstrate that treatment with demethylating agents may engender the reexpression and function of the androgen receptor in AR-negative cell lines.

Methylation of the androgen receptor minimal promoter silences transcription in human prostate cancer.

Advanced hormone-independent prostate cancer is characterized by a significant loss of androgen receptor (AR) expression in 20-30% of the tumors. The transcriptional block underlying this phenomenon is not known, but we have proposed that methylation of CpG sites in the AR promoter may reversibly inactivate transcription of the AR (D. F. Jarrard et al, Cancer Res., 58: 5310-5314, 1998). In this study, detailed methylation analysis using bisulfite sequencing was performed on a series of AR expression-positive and -negative prostate cancer cells. We found that methylation of several consensus sequences in the AR promoter (from -131 to -121 and +44 to +54) are tightly linked to the loss of AR expression in metastatic hormone-independent prostate cancer cell lines. These consensus sites of methylation correlate with the minimal promoter region critical for AR transcription. In human tissues, no methylation was demonstrated in normal or primary prostate cancers that express the AR. Four of 15 tumors obtained from men who had died from hormone-independent prostate cancer demonstrated a significant loss of AR expression immunohistochemically and two (50%) of these AR-negative tumors contained AR methylation. We conclude that the AR promoter contains specific CpG methylation hot spots that are markers for gene silencing. Furthermore, AR methylation may represent a phenotype important in the development of hormone independence in a subset of advanced prostate cancer in which AR expression is lost. The finding of AR methylation also represents the first report of aberrant methylation on an X-linked gene associated with a somatic male cancer.

HER-2/neu gene amplification characterized by fluorescence in situ hybridization: poor prognosis in node-negative breast carcinomas.

PURPOSE: The HER-2/neu gene codes for a membrane receptor protein that is homologous, but distinct from the epidermal growth factor receptor. This investigation was performed to validate fluorescence in situ hybridization (FISH) as a sensitive and specific method for assessing HER-2/neu gene amplification in archival tissue and to test whether this alteration is associated with poor prognosis. MATERIALS AND METHODS: HER-2/neu gene amplification was determined by FISH in 140 archival breast cancers, previously characterized for gene amplification by Southern hybridization or dot-blot hybridization, and for gene expression by Northern hybridization, Western immunoblot, or immunohistochemistry. A separate cohort of 324 node-negative breast cancers was assessed for amplification by FISH to determine the utility of HER-2/neu gene amplification. RESULTS: Relative to solid-matrix blotting procedures, FISH analysis of HER-2/neu gene amplification showed a sensitivity of 98% and a specificity of 100% in 140 breast cancers. Among patients treated by surgery only, the relative risks (relative hazard) of early recurrence (recurrent disease within 24 months of diagnosis), recurrent disease (at any time), and disease-related death were statistically significantly associated with amplification. The prognostic information contributed by HER-2/neu amplification was independent of the other markers studied. CONCLUSION: FISH was an alternative technique for determining gene amplification and had some distinct advantages over Southern hybridization. Our results demonstrate that HER-2/neu gene amplification in the absence of adjuvant therapy is an independent predictor of poor clinical outcome and is a stronger discriminant than tumor size. Women with small tumors that had gene amplification were at increased risk of recurrence and disease-related death.

Quantifying chromosome changes and lineage involvement in myelodysplastic syndrome (MDS) using fluorescent in situ hybridization (FISH).

A simplified technique for fluorescent in situ hybridization (FISH) was used to investigate the prevalence of chromosomally abnormal clones in 13 cases of myelodysplastic syndrome (MDS). Biotinylated centromeric probes for chromosomes 7, 8, 12 and X, as well as painting probes for chromosomes 7 and 11, were applied to air-dried bone marrow smears stored from 6 to 23 months. Nine of the cases had been previously karyotyped, and five of these demonstrated normal karyotypes which were confirmed by FISH. The remaining four cases showed different chromosome changes. One case of sideroblastic anemia with chronic lymphocytic leukemia showed minor clones with either monosomy 12 (12% of cells) or tetraploidy (15% of cells) by FISH, whereas metaphase cytogenetics had demonstrated trisomy 12 in 20% of cells, with no evidence of tetraploidy. Another case which had been previously karyotyped was found to have a t(7;11) in 90% of cells while only 10% of cells were shown by FISH to contain this translocation. Monosomy 7 was demonstrated by FISH in a case of refractory anemia (RA), while trisomy 8 was found in a case of RA with excess blasts in transformation (RAEB-T), and in both of these cases the aneuploid clone was present in eosinophils as well as in erythroid and granulocytic precursors but not in lymphocytes or histiocytes, thereby demonstrating the value of FISH for identifying the affected cell lineage.

Extensive amplification of bcr/abl fusion genes clustered on three marker chromosomes in human leukemic cell line K-562.

Using fluorescence in situ hybridization (FISH), we were able to demonstrate 22-24-fold amplification of the bcr/abl fusion gene in the human leukemic cell line K-562. About 60% of the amplified sequences are localized to a large acrocentric marker chromosome, with another 30% clustered on a small acrocentric chromosome. In addition to these two masked Ph chromosomes, the remaining bcr/abl fusion genes are located on a der(2) distal to band q33. G- and C-banding analysis revealed similar unique banding patterns in both masked Ph chromosomes and suggests that amplification occurred by tandem duplication of the bcr/abl fusion site. Because the number of bcr/abl fusion genes may be increasing over time, it is critical that researchers using K-562 cells should be aware of this extensive amplification.

Establishment and characterization of an Epstein-Barr virus spontaneously transformed lymphocytic cell line derived from a hairy cell leukemia patient.

Hairy cell leukemia is a rare, B-cell malignancy uniquely sensitive to the antitumor effects of alpha and beta interferons (IFN). In order to further study the effects of IFN in this disease, we derived a cell line (HC1) from the peripheral blood mononuclear cells of a patient with hairy cell leukemia (HCL). Cells exhibited the typical morphological features of HCL, including the characteristic cytoplasmic projections by light, transmission, and scanning electron microscopy. HC1 cells were of B-cell lineage, as evidenced by immunophenotypic analysis. Although originally TRAP positive, HC1 cells lost this biochemical marker following 3 months in culture. Monoclonality of the cell line was confirmed by a clonal karyotypic abnormality characteristic of B-cell malignancies, and the presence of a single, distinctive fused terminal EBV fragment. The cells formed colonies in soft agar and were tumorigenic in irradiated nude mice. HC1 cells were sensitive to the antiproliferative effects of IFN-a and IFN-beta, but only moderately sensitive to the growth inhibitory effects of IFN-gamma. Incubating the cells in the presence of Type 1 IFN resulted in stabilization of cell numbers, without cellular proliferation or loss. Cell cycle analysis revealed that IFN-alpha resulted in a build-up of cells in the S phase of the cell cycle, suggesting a cytostatic effect of IFN on the growth of these cells. The HC1 cell line provides a model system which will be useful for in vitro studies of the biology and treatment of this disease.

Normal growth and differentiation in a spontaneously immortalized near-diploid human keratinocyte cell line, NIKS.

We report the isolation and characterization of a spontaneously immortalized human keratinocyte cell line, NIKS. The cell line is not tumorigenic in athymic nude mice and maintains cell-type-specific requirements for growth in vitro. NIKS cells express steady-state levels of transforming growth factor-alpha, transforming growth factor-beta1, epidermal growth factor receptor, c-myc, and keratin 14 mRNAs comparable with the parental BC-1-Ep keratinocyte strain. BC-1-Ep and NIKS keratinocytes produce similar levels of cornified envelopes and nucleosomal fragmentation in response to loss of substrata attachment. DNA fingerprinting results confirm that the NIKS cells originated from the parental BC-1-Ep keratinocytes. NIKS cells contain 47 chromosomes due to an extra isochromosome of the long arm of chromosome 8, and the near-diploid karyotype appears to be stable with repeated passage. A fully stratified squamous epithelium is formed by the NIKS keratinocytes in organotypic culture. Ultrastructural analysis of both the parental and immortalized keratinocytes reveals abundant desmosomes, hemidesmosomes, and the production of a basal lamina. Our findings with the NIKS cells support the observation that spontaneous immortalization is not linked to alterations in squamous differentiation or the ability to undergo apoptosis. The NIKS human keratinocyte cell line is an important new tool for the study of growth and differentiation in stratified squamous epithelia.

DNA polymerase alpha defect in the N syndrome.

The N syndrome is characterized by mental retardation, malformations, chromosome breakage, and development of T-cell leukemia (Opitz et al.: Proceedings of the II International Congress IASSMD pp 115-119, 1971; Hess et al.: Clinical Genetics 6:237-246, 1974b, American Journal of Medical Genetics [supplement] 3:383-388, 1987). N syndrome fibroblasts were studied to see if the high chromosome breakage rate associated with this apparently X-linked syndrome could be related to a deficiency of DNA polymerase alpha, a product of a gene localized to the X chromosome. Bleomycin, which is known to break double-stranded DNA, produced increased chromosome breakage in normal control, Fanconi anemia, and N syndrome fibroblasts. When aphidicolin was used to inhibit repair mediated by DNA polymerase alpha, both normal control and Fanconi anemia fibroblasts showed significantly more chromosome breakage than was produced by bleomycin alone, but there was no increase in the amount of breakage seen in the N syndrome fibroblasts over that seen with bleomycin alone. This suggests that the N syndrome is due to a mutation affecting the region of the X chromosome on which the gene for DNA polymerase alpha is located, and that the high risk of T-cell leukemia observed in the hemizygote is due to this DNA repair defect.

The trisomy 4p syndrome: case report and review.

We report a further case of trisomy 4p: a 5-year-old mentally retarded boy with characteristic facial features, eye abnormalities, flexion contractures, several bone anomalies, and hyperactivity. In a review of 27 cases (11 male, 16 female, 22 families) the cytogenetic and clinical data were tabulated and analyzed. Diagnosis is established by karyotype: there is always partial or apparently "total" trisomy of the short term arm of chromosome 4. In 19 families a parent carried either a balanced translocation (16 times) or a pericentric inversion (3 times); 3 patients had de novo duplication of 4p. In several cases, additional deletions or trisomies were present. From the analysis of all cases, but particularly of the "pure" trisomies, the phenotypic spectrum of this condition was observed and found to be a specific multiple congenital anomaly/mental retardation (MCA/MR) syndrome. Its main features are a characteristic facial appearance, postnatal growth retardation, severe psychomotor retardation with or without seizures, microcephaly, and various major and minor anomalies.

The dup(3q) syndrome: report of eight cases and review of the literature.

Clinical and cytogenetic examinations were performed on eight unrelated infants with duplication of part of the long arm of chromosome 3. A review of published cases shows a clinical syndrome characterized by statomotoric retardation, shortened life span, and a multiple congenital anomalies (MCA) syndrome of abnormal head configuration, hypertrichosis, hypertelorism, ocular anomalies, anteverted nostrils, long philtrum, maxillary prognathia, down-turned corners of the mouth, highly arched or cleft plate, micrognathia, malformed auricles, short, webbed neck, clinodactyly, simian crease, talipes, and congenital heart disease. The dup(3q) syndrome is a clinically easily recognizable entity.

Toward quality assurance for metaphase FISH: a multi-center experience.

Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multi-center determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for SNRPN and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and 2 control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15) (q11.2-->q12) and 15 with normal 15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 minutes; slides processed in batches of 4 and analyzed singly required 36.9 minutes. We conclude that proficiency testing for FISH using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.

Toward quality assurance for metaphase FISH: a multicenter experience.

Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multicenter determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for small nuclear ribonucleoprotein polypeptide N (SNRPN) and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid, and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and two control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15)(q11.2-->q12) and 15 with normal #15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete, or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made, including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 min; slides processed in batches of 4 and analyzed singly required 36.9 min. We conclude that proficiency testing for FISH by using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.