Selective transfer of individual human chromosomes to recipient cells.

Two hypoxanthine phosphoribosyltransferase-deficient human cell lines, D98/AH-2 and HT1080-6TG, were stably transfected with pSV2 gpt, a plasmid containing the selectable marker Escherichia coli xanthine-guanine phosphoribosyl transferase (Eco gpt). Hypoxanthine-aminopterin-thymidine-resistant transformants arose with a frequency of ca. 10(-6) and contained mostly single, but occasionally multiple, copies of the plasmid sequences. These transformants actively express the Eco gpt marker. Single chromosomes from two different HT1080 gpt transformants and one D98 gpt transformant, containing the integrated plasmid sequences, were transferred via microcell-mediated chromosome transfer to hypoxanthine phosphoribosyl transferase-deficient mouse A9 cells. The transferred human chromosomes were identified as 2, 4, and 22, by using a combination of G-11 staining, G-banding, isoenzyme analysis, and in situ hybridization. This system is being used to create a library of interspecies microcell hybrid clones, each clone containing a unique single human chromosome in a mouse background. The complete library will represent the entire human karyotype.

Implication of chromosome 11 in the suppression of neoplastic expression in human cell hybrids.

Cytogenetic analyses of intraspecies human HeLa X fibroblast hybrid cell populations have provided tentative evidence for the correlation of loss of a single copy of chromosomes 11 and 14 with reexpression of tumorigenicity. In this study paired combinations of nontumorigenic and tumorigenic segregant HeLa X fibroblast hybrid cells from two independent fusion events were examined for the presence or absence of normal chromosomes 11 and 14. In human hybrid cell lines the parental origin of chromosomes can be distinguished on the basis of restriction fragment length polymorphisms. Genes for c-Ha-ras, insulin, and apolipoprotein A-1 on chromosome 11 and a polymorphic locus AW101 on chromosome 14 were used as Southern hybridization probes. Analysis of DNA from the parental fibroblast and HeLa cell lines and their nontumorigenic and tumorigenic hybrids showed the loss of a fibroblast chromosome 11 in four of the tumorigenic segregants and a HeLa chromosome 11 in a fifth hybrid cell line. This latter segregant has, interestingly, also lost a copy of chromosome 14 of fibroblast origin. There was no obvious correlation of loss of a copy of normal chromosome 14 and reexpression of tumorigenicity in any of the other hybrid cell populations. Our conclusion from these observations is that gene(s) that map to normal chromosome 11 might be involved in control of tumorigenic expression in these human hybrid cells.

Complete or partial homozygosity of chromosome 13 in primary retinoblastoma.

Sixteen retinoblastomas were examined with chromosome 13 polymorphic probes to determine the frequency of homozygosity for the chromosome in the tumors. Each of the tumors had two cytogenetically normal appearing No. 13 chromosomes. Nontumorous cells from the same patients were heterozygous for the various polymorphic chromosome 13 probes used. At least partial homozygosity for a single chromosome 13 was observed in 75% of the tumors. These studies confirm and extend previous studies which suggest that homozygosity or hemizygosity at RBI occurs in the majority of retinoblastomas. We also demonstrate in an additional tumor that rapid clonal evolution from hemizygosity to homozygosity can occur in the tumor.

Loss of a putative tumor suppressor locus after gamma-ray-induced neoplastic transformation of HeLa x skin fibroblast human cell hybrids.

The nontumorigenic HeLa x skin fibroblast hybrid cell line, CGL1, can be induced to re-express HeLa tumor-associated cell surface antigen, p75-IAP (intestinal alkaline phosphatase), with resulting neoplastic transformation, by exposure to gamma radiation. This has allowed the human hybrid system to be developed into a quantitative in vitro model for radiation-induced neoplastic transformation of human cells. Recently, several gamma-ray-induced IAP-expressing mutants (GIMs) of the nontumorigenic HeLa x skin fibroblast hybrid CGL1 were isolated and all were tumorigenic when injected subcutaneously into nude mice (Mendonca et al., Cancer Res. 51, 4455-4462, 1991). Control cell lines which were negative for p75-IAP (CONs) were also isolated from irradiated populations, and none were found to be tumorigenic. We have now begun to investigate the molecular basis of radiation-induced neoplastic transformation in this system by studying the potential genetic linkage between p75/IAP expression, tumorigenicity and damage to a putative tumor suppressor locus on fibroblast chromosome 11. Previous analysis of rare spontaneous segregants has indicated that this locus is involved in the regulation of tumorigenicity and in the expression of the HeLa tumor-associated cell surface marker intestinal alkaline phosphatase (p75-IAP) in this system. Therefore, analysis by restriction fragment length polymorphism and chromosome painting have been performed for chromosome 11, and for chromosome 13 as a control, for the p75/IAP-positive GIM and p75/IAP-negative CON cell lines. We report that in five of eight of the GIMs large-scale damage to the fibroblast chromosome 11's is evident (four GIMs have lost one complete copy of a fibroblast chromosome 11 and one GIM has both copies of fibroblast chromosome 11 heavily damaged). None of the CONs, however (0/5), have lost a complete copy of either fibroblast chromosome 11. No large-scale damage to the control chromosome 13's was detected in the GIMs or CONs. The data further suggest that both copies of fibroblast chromosome 11 contain an active locus and that radiation-induced loss of either fibroblast chromosome 11 will result in neoplastic transformation in this system. We conclude that it is the loss of a putative tumor suppressor locus on fibroblast chromosome 11 which is responsible at least in part for radiation-induced neoplastic transformation of these human hybrid cells.

Alternative mRNA splicing in colon cancer causes loss of expression of neural cell adhesion molecule.

BACKGROUND: The neural cell adhesion molecule (NCAM) has numerous isoforms resulting from alternative splicing of mRNA. The 3 major isoforms found in adult tissue are (1) a 120-kDa protein that is linked to the plasma membrane by glycosylphosphatidylinositol; (2) a 140-kDa form that has a transmembrane component and a cytoplasmic tail with unknown function; and (3) a 180-kDa isoform that has an intracellular protein that binds the cytoskeleton. NCAM is capable of homotypic binding and therefore plays a role in cell-cell adhesion for cells expressing the 180-kDa isoform by anchoring groups of cells into epithelial sheets. NCAM-180 is the isoform found in colonocytes, and loss of expression is associated with clinically aggressive colon cancers. METHODS: Western blotting and reverse transcriptase-polymerase chain reaction were used to screen commercially available cell lines for NCAM-180 expression. For cell-line pairs with differential NCAM-180 expression, exon analysis was performed with reverse transcriptase-polymerase chain reaction to determine where the molecule was spliced, culminating in failed expression. These results were confirmed with exon analysis in colon cancers harvested at the time of laparotomy. RESULTS: Analysis of a SW480 cell line (derived from a patient's primary colon cancer lesion) revealed NCAM-180 expression, whereas no expression was found in the SW620 cell line (derived from a metastatic lesion from the same patient). Exon analysis of NCAM mRNA transcripts from SW620 revealed that the transcripts were truncated after exon 12. This region correlates to an area between 2 fibronectin-III domains on the NCAM protein. CONCLUSIONS: The most common site for NCAM alternative splicing is between the 2 fibronectin-III domains corresponding to the border between exons 12 and 13 of the NCAM gene. Loss of NCAM-180 expression in aggressive colon carcinoma results from a splice defect in the same area, which may result in defective intracellular adhesion between colonocytes.

Loss of heterozygosity in squamous cell carcinomas of the head and neck defines a tumor suppressor gene region on 11q13.

Tumor suppressor genes APC, RB1, and DCC, as well as genes localized to 3p and 11q, have been implicated in the development of a number of human tumors. To determine whether allelic deletions occur at these loci in squamous cell carcinomas (SSCs) of the head and neck, 25 primary, 1 metastatic, and 3 recurrent tumors, along with the corresponding constitutional tissues, were analyzed by using a battery of polymorphic DNA markers. For two primary tumors, we also analyzed subsequent metastatic tumors of the lung. Polymerase chain reaction-based restriction fragment length polymorphism studies demonstrated loss of heterozygosity for the APC gene in 2 of 12 (17%), the RB1 gene in 5 of 22 (23%), and the DCC gene in 5 of 13 (38%) informative cases. Alleles on chromosomes 3p, 11q13, and 18q21.1 were lost in 7 of 20 (35%), 9 of 23 (39%), and 4 of 17 (24%) informative cases, respectively. A breakpoint was identified within the chromosomal region 3p13-21.2 in a SCC of the tongue. Breakpoints within 11q13 were identified in 2 additional tumors. Thus, allelic deletions of DCC, 3p, and 11q13 appear to be common in head and neck cancers, suggesting that these genes play a critical and complex role in the development of these tumors. Furthermore, the present study provides definitive evidence for a tumor suppressor gene at chromosome band 11q13 and localizes this gene to the INT2-D11S533 interval for future cloning and sequencing.

Rearrangement of chromosome band 11q13 in HeLa cells.

Previous somatic cell genetic and molecular genetic studies have localized the Hela cell tumor suppressor gene to the long arm of chromosome 11. To determine if loss of heterozygosity has occurred for the inactivation of the tumor suppressor gene, we investigated the molecular status of chromosome 11 in the HeLa cells. The restriction fragment length polymorphic (RFLP) analysis of four different HeLa sublines showed retention of heterozygosity for the long and short arm specific probes in three of the sublines. Fluorescence in situ hybridization (FISH) studies using whole chromosome painting probes identified 11 material in a marker chromosome in addition to the two normal appearing 11's in these three cell lines. The fourth cell line contained only two 11's. This cell line had lost the 11 material from the marker chromosome. Both molecular and karyotypic analyses indicated q13 as the common site of rearrangement in the derivation of these marker chromosomes. We therefore conclude that 11q13 rearrangement could contribute to the abnormal growth behaviour of HeLa cells in vivo and/or in vitro.

Detection of chromosome 11q13 amplification in head and neck cancer using fluorescence in situ hybridization.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) remains a cancer with one of the lowest five-year survival rates. Despite a better understanding of the disease and recent advances in diagnosis and treatment, survival rates for HNSCC patients have not improved. Chromosomal abnormalities are common in HNSCC, and aberrations of chromosome 11q13 have been correlated with a poor prognosis. MATERIALS AND METHODS: In this study we utilized fluorescence in situ hybridization (FISH) to determine the incidence of 11q13 amplification in twenty primary HNSCC tumors. INT-2 was used as the 11q13 probe, and 9 and 11 centromeric probes were used as controls. RESULTS: Polysomy, greater than two copies of chromosome 11, was found in 2 of 20 tumors. INT2 (11q13) amplification was found in 3 other tumors. CONCLUSIONS: These preliminary studies indicate tht analysis of a larger sample of tumors using FISH may yield important diagnostic and prognostic information about head and neck tumors.

Antisense cyclin D1 enhances sensitivity of head and neck cancer cells to cisplatin.

OBJECTIVES: Cyclin D1 is a cell cycle regulatory factor that modulates a critical step in cell cycle control. Cyclin D1 is overexpressed in a significant proportion of head and neck cancers and correlates with a poor prognosis. Abrogation of cyclin D1 action through antisense cyclin D1 shows promise as an antitumor therapy, with an inhibitory effect in head and neck squamous cell carcinoma both in vitro and in vivo. The suppressive effect of antisense cyclin D1 in head and neck cancer xenografts in nude mice is incomplete, however, suggesting that combination with another antitumor agent is necessary for complete tumor eradication. Cisplatin is a widely used chemotherapeutic agent in head and neck cancer, and is particularly effective in combination with radiation therapy. In this study, we investigate whether antisense cyclin D1 enhances the sensitivity of head and neck cancer cells to cisplatin. Such an enhancement of sensitivity would suggest that combination therapy using antisense cyclin D1 and cisplatin would be an effective treatment modality for head and neck cancer. STUDY DESIGN: Antisense cyclin D1 was transfected into the head and neck squamous cell carcinoma cell line CCL23 using a plasmid vector. Both the parental CCL23 cells and the antisense cyclin D1-transfected CCL23 cells (CCL23AS) were treated with cisplatin at increasing concentrations. The dosage of cisplatin ranged from 1 microg/mL to 10 microg/mL. Initial exposure to cisplatin was for 2 hours, with increasing exposure times in succeeding experiments. Cell viability assays were done following cisplatin exposure. Dose response curves for the two cell lines were plotted and compared. Western blot analyses were done on the cisplatin-treated cell lines to determine levels of cyclin D1 expression. RESULTS: Increasing concentrations of cisplatin resulted in significantly higher rates of cell killing in the antisense cyclin D1-transfected cells than in the parental cells. The ID50 values for the parental CCL23 cells and the antisense cyclin D1-transfected CCL23 cells were 7 microg/mL and 3 microg/mL, respectively, indicating significant enhancement of sensitivity to cisplatin in the antisense cyclin D1-transfected cells. Western blot analyses demonstrated decreased expression of cyclin D1 in the CCL23AS cells with increasing doses of cisplatin, compared with the parental CCL23 cells. CONCLUSIONS: Antisense cyclin D1-transfected CCL23 cells demonstrate an enhanced sensitivity to the effects of cisplatin compared with the parental cell line. Although the mechanism for this phenomenon is not completely understood, the data suggests the potential use of combination therapy using antisense cyclin D1 and cisplatin for head and neck cancers. While neither agent alone can completely eradicate head and neck cancers, the synergistic effect of the two may be an effective therapeutic protocol for refractory head and neck cancers. Future investigation into the combination of antisense cyclin D1 with cisplatin for treatment of head and neck cancer is needed.

Increased expression of transforming growth factor-beta1, acidic fibroblast growth factor, and basic fibroblast growth factor in fetal versus adult fibroblast cell lines.

OBJECTIVES: Fetal wound healing occurs without scar tissue formation. Differences in growth factor expression between fetal and adult fibroblasts have been explored. Recently we used RNA expression studies to demonstrate that transforming growth factor (TGF)-beta1, acidic fibroblast growth factor (alpha-FGF), and basic fibroblast growth factor (beta-FGF) could be detected in both fetal and adult fibroblast cell lines. In addition, adult fibroblasts showed greater relative expression of these growth factors than fetal fibroblasts. The aim of this study was to identify the level of protein expression in fetal and adult fibroblasts. STUDY DESIGN/METHODS: Fetal and adult fibroblasts were grown in culture using standard and serum-free media. After protein extraction, Western blot studies were performed to detect the presence and amount of TGFbeta-1, alpha-FGF, and beta-FGF growth factor proteins. beta-Tubulin was used as a control. RESULTS: TGFbeta-1, alpha-FGF, and beta-FGF proteins were detected in fetal and adult fibroblasts grown in standard and serum-free media. The fetal fibroblasts showed higher levels of all three growth factor proteins compared with the adult fibroblasts. CONCLUSIONS: Western blot studies suggest higher levels of TGFbeta-1, alpha-FGF, and beta-FGF expression in fetal fibroblasts. It is clear that significant differences exist in the expression/production of these growth factors and it seems likely that further study of these differences will help elucidate the unique healing capabilities of fetal fibroblasts.

Clinical application of fluorescence in situ hybridization for chromosome 11q13 analysis in head and neck cancer.

OBJECTIVE: Squamous cell carcinoma of the head and neck (HNSCC) still has one of the lowest 5-year survival rates. Despite advances in diagnosis, treatment, and research, survival rates have not improved in recent years. This report examines the utility of fluorescence in situ hybridization (FISH) in detecting chromosome 11q13 amplification in HNSCC and in evaluating the correlation between 11q13 amplification and tumor behavior. STUDY DESIGN: This study used FISH to determine the incidence of 11q13 amplification in 20 HNSCCs and 10 normal controls from the same patients. Tumor touch preparations and paraffin-embedded tissues from the same patient samples were used for comparative analysis. Both single and dual color FISH was performed. METHODS: Repetitive chromosome 11 specific alpha satellite DNA probe and chromosome 11q13 specific probe cyclin D1 were used for the FISH analysis. RESULTS: Experiments revealed amplification of chromosome 11q13 in three fresh touch preparations. FISH on paraffin tissues showed amplification in two additional samples. Intensity of amplification, as high as 20 copies per nucleus, was observed in paraffin preparations, whereas a maximum of only six copies was seen in fresh preparations. Amplification was not detected in any of the normal samples. All five cases with 11q13 amplification had metastases and four of these were from poorly differentiated tumors. In the nonamplified cases, 5 of 15 had metastases and 2 of 15 was poorly differentiated. CONCLUSIONS: The present study indicates that FISH is a useful technique for detecting molecular changes such as amplification of chromosome 11q13 in HNSCC. FISH in paraffin preparations allows for accurate measurement of intensity of amplification and makes it possible for the evaluation of a large collection of archival material. The data also suggest that 11q13 amplification is correlated with poorly differentiated tumors and metastasis. Thus FISH has the potential to be a valuable diagnostic/prognostic tool in head and neck cancers.

Deletion analysis of the p16/CDKN2 gene in head and neck squamous cell carcinoma using quantitative polymerase chain reaction method.

BACKGROUND: Recently, the p16/CDKN2/MTS1 gene in the 9p21-22 region has been offered as a candidate tumor suppressor gene. We examined the frequency of hemizygous and homozygous deletions of p16/CDKN2 in head and neck squamous cell carcinoma (HNSCC) using a quantitative polymerase chain reaction (PCR) method. DESIGN: Twenty-one HNSCC and 12 corresponding normal DNA samples were examined for deletion of p16/ CDKN2 using PCR amplification and fluorescent quantification of DNA. All tumor and normal DNA samples were also amplified with fluorescein-labeled primers for a control DNA marker on chromosome 8p (D8S265). The ratios of the observed fluorescence of the p16/CDKN2 and 8p PCR products were compared. SETTING AND PARTICIPANTS: Patients with HNSCC scheduled to undergo surgical resection of their tumors were recruited. After the specimen was removed, a portion of the tissue was snap frozen for further DNA extraction. RESULTS: Eight tumors (38%) had p16/CDKN2-D8S265 ratios of greater than 0.75; 8 tumors (38%), from 0.25 to 0.75; and 5 tumors (24%), of less than 0.25, the average ratio in this last group being 0.06. CONCLUSIONS: These ratios suggest a higher rate of homozygous deletion than previously reported and significant probable hemizygous deletion of the p16/CDKN2 gene in HNSCC.

Comparison of growth factor expression in fetal and adult fibroblasts: a preliminary report.

BACKGROUND: Fetal wounds can heal without any histological evidence of scarring. Fetal wounds lack the inflammatory infiltrate characteristic of adult wounds, and the fetal environment is not necessary for scarless healing to occur. Recent evidence suggests that fibroblasts are the main effector of scarless healing in fetal tissue. What has not been shown is what profile of growth factors the fibroblast uses to influence wound repair. OBJECTIVE: To determine the expression of growth factors (transforming growth factors beta1, beta2, and beta3; acidic and basic fibroblast growth factors; keratinocyte growth factor; and platelet-derived growth factor AA, BB, and AB) of fetal and adult fibroblasts in vitro. DESIGN: Adult and fetal fibroblasts were grown in culture, and messenger RNA was extracted by standard techniques. Northern hybridization was used to identify messenger RNA transcripts for the aforementioned growth factors. Densitometry was used to compare growth factor messenger RNA expression with that of a ubiquitously expressed control, glyceraldehyde phosphate dehydrogenase. RESULTS: The data suggest that fetal and adult fibroblasts express acidic and basic fibroblast growth factor and transforming growth factor beta1. Adult fibroblasts show twice the relative expression of these growth factors compared with fetal fibroblasts. CONCLUSIONS: The adult fibroblasts demonstrate a relative excess production of cytokines compared with fetal fibroblasts. This is thought to contribute to suboptimal wound healing in adult wounds compared with the scarless healing of fetal wounds.

Inhibition of cell proliferation in head and neck squamous cell carcinoma cell lines with antisense cyclin D1.

Cyclin D1 and cyclin G are essential regulatory factors in the progression of the cell cycle from G0 through G1 and S phase. Aberrations in expression of these cyclins may lead to dysregulated cellular proliferation that could result in neoplasia. Amplification and overexpression of cyclin D1 have been observed in many human cancers, whereas cyclin G is a new cyclin recently described in osteosarcoma cells. This study was performed to determine whether these cyclins were amplified in head and neck squamous cell carcinoma (HNSCC) tumors. Polymerase chain reaction of DNA extracted from 22 HNSCC primary tumors and three HNSCC cell lines did not reveal amplification of cyclin D1 in any of the tumor samples. Southern blot analysis identified amplification of cyclin D1 in a single tumor. Amplification of cyclin G was not observed in any of the tumors by Southern blot hybridization with a cyclin G probe. HNSCC cell lines transfected with antisense cyclin D1 were tested for cell proliferation by the incorporation of 3H-thymidine into cells grown in serum-free media. By 72 hours of incubation, there was a greater than 30% reduction in proliferation of cells transfected with antisense cyclin D1 as compared with non-transfected control cells. The results indicate that cyclin D1 may play an important role in the growth and proliferation of HNSCC cells.

Third place--Resident Research Competition, AAO-2000. Antisense cyclin D1 inhibits growth of head and neck cancer xenografts in nude mice.

PROBLEM: Cyclin D1 is a regulatory factor essential in the progression of the cell cycle from G1 through S phase. Amplification and overexpression of cyclin D1 have been observed in many human cancers including head and neck squamous cell carcinoma (HNSCC). We have previously transfected a HNSCC control cell line (CCL23) with an antisense cyclin D1 plasmid and demonstrated inhibition of cell proliferation in vitro. In this study, we examine whether antisense cyclin D1 could inhibit tumor growth in vivo. Methods/measures: The CCL23 and its antisense cyclin D1 transfected clone (CCL23 AS) were injected into the flanks of nude mice. Tumor growth was monitored weekly. After 5 weeks, tumors were removed and studied for tumor size, cyclin D1 expression, cyclin D1-dependent kinase activity, and retinoblastoma (Rb) phosphorylation. RESULTS: Compared with the control tumors, 11 of 19 antisense tumors were smaller, 7 tumors were of equal size, and 1 tumor was larger. Immunohistochemical analysis with an anti-cyclin D1 antibody demonstrated decreased cyclin D1 expression in CCL23 AS and the smaller antisense tumors. Cyclin D1-dependent kinase activity was reduced in CCL23 AS and the smaller antisense tumors, and this was accompanied by a relative decrease in phosphorylated Rb in these samples. CONCLUSION: Antisense cyclin D1 inhibits growth of HNSCC tumors. Cyclin D1 expression, cyclin D1-dependent kinase activity, and Rb phosphorylation are decreased in these tumors. CLINICAL SIGNIFICANCE: These findings lend support for the potential use of antisense cyclin D1 as gene therapy for HNSCC.

Localization of HeLa cell tumor-suppressor gene to the long arm of chromosome II.

Cytogenetic and molecular genetic analyses of human intraspecific HeLa x fibroblast hybrids have provided evidence for the presence of a tumor-suppressor gene(s) on chromosome 11 of normal cells. In the present study, we have carried out extensive RFLP analysis of various nontumorigenic and tumorigenic hybrids with at least 50 different chromosome 11-specific probes to determine the precise location of this tumor-suppressor gene(s). Two different hybrid systems, (1) microcell hybrids derived by the transfer of a normal chromosome 11 into a tumorigenic HeLa-derived hybrid cell and (2) somatic cell hybrids derived by the fusion of the HeLa (D98OR) cells to a retinoblastoma (Y79) cell line, were particularly informative. The analysis showed that all but one of the nontumorigenic hybrid cell lines contained a complete copy of the normal chromosome 11. This variant hybrid contained a segment of the long arm but had lost the entire short arm of the chromosome. The tumorigenic microcell and somatic cell hybrids had retained the short arm of the chromosome but had lost at least the q13-23 region of the chromosome. Thus, these results showed a perfect correlation between the presence of the long arm of chromosome 11 and the suppression of the tumorigenic phenotype. We conclude therefore that the gene(s) involved in the suppression of the HeLa cell tumors is localized to the long arm (q arm) of chromosome 11.

Inhibition of virion-associated reverse transcription by nucleoside triphosphatase in avian myeloblastosis virus.

RNA-dependent DNA polymerase activity of avian myeloblastosis virions as measured by the incorporation of [3H]TTP into trichloroacetic acid-precipitable material was very low. This apparent low polymerase activity was observed with virions isolated either from leukemic chicken plasma or from the supernatant of cultured leukemic myeloblasts. The inhibition of reverse transcriptase activity was caused by nucleoside triphosphatase present in avian myeloblastosis virions and could be reversed by ADP.

Deletion of chromosome 11 and of 14q sequences in neuroblastoma.

Restriction fragment length polymorphism (RFLP) analysis carried out on 45 primary neuroblastomas showed deletion of chromosome 11 sequences in 12 of 37 (32%) informative cases. Both 11p and 11q probes were informative in seven tumors; loss of all of chromosome 11, of only 11p sequences, and of only 11q sequences was observed in 4, 1, and 2 tumors, respectively. A cytogenetic abnormality involving translocation of chromosome arm 11q to chromosome arm 1p was observed in a primary tumor. Deletion of 14q was observed in 6 of 27 (22%) informative cases. Deletion of chromosome 11 but not 14q may correlate with regional and metastatic disease. These results suggest a possible role for sequences localized to chromosome 11 and to 14q in the development and/or progression of neuroblastoma.