Human HST1 (HSTF1) gene maps to chromosome band 11q13 and coamplifies with the INT2 gene in human cancer

FADS2 function at the major cancer hotspot 11q13 locus alters fatty acid metabolism in cancer

Dysregulation of fatty acid metabolism and de novo lipogenesis is a key driver of several cancer types through highly unsaturated fatty acid (HUFA) signaling precursors such as arachidonic acid. The human chromosome 11q13 locus has long been established as the most frequently amplified in a variety of human cancers. The fatty acid desaturase genes (FADS1, FADS2 and FADS3) responsible for HUFA biosynthesis localize to the 11q12-13.1 region. FADS2 activity is promiscuous, catalyzing biosynthesis of several unsaturated fatty acids by Δ6, Δ8, and Δ4 desaturation. Our main aim here is to review known and putative consequences of FADS2 dysregulation due to effects on the 11q13 locus potentially driving various cancer types. FADS2 silencing causes synthesis of sciadonic acid (5Z,11Z,14Z-20:3) in MCF7 cells and breast cancer in vivo. 5Z,11Z,14Z-20:3 is structurally identical to arachidonic acid (5Z,8Z,11Z,14Z-20:4) except it lacks the internal Δ8 double bond required for prostaglandin and leukotriene synthesis, among other eicosanoids. Palmitic acid has substrate specificity for both SCD and FADS2. Melanoma, prostate, liver and lung cancer cells insensitive to SCD inhibition show increased FADS2 activity and sapienic acid biosynthesis. Elevated serum mead acid levels found in hepatocellular carcinoma patients suggest an unsatisfied demand for arachidonic acid. FADS2 circular RNAs are at high levels in colorectal and lung cancer tissues. FADS2 circular RNAs are associated with shorter overall survival in colorectal cancer patients. The evidence thusfar supports an effort for future research on the role of FADS2 as a tumor suppressor in a range of neoplastic disorders.

The potential of fibroblast growth factor/fibroblast growth factor receptor signaling as a therapeutic target in tumor angiogenesis

INTRODUCTION

Fibroblast growth factors (FGFs) are endowed with a potent pro-angiogenic activity. Activation of the FGF/FGF receptor (FGFR) system occurs in a variety of human tumors. This may lead to neovascularization, supporting tumor progression and metastatic dissemination. Thus, a compelling biologic rationale exists for the development of anti-FGF/FGFR agents for the inhibition of tumor angiogenesis in cancer therapy.

AREAS COVERED

A comprehensive search on PubMed was performed to identify studies on the role of the FGF/FGFR system in angiogenesis. Endothelial FGFR signaling, the pro-angiogenic function of canonical FGFs, and their role in human tumors are described. In addition, experimental approaches aimed at the identification and characterization of nonselective and selective FGF/FGFR inhibitors and their evaluation in clinical trials are summarized.

EXPERT OPINION

Different approaches can be envisaged to inhibit the FGF/FGFR system, a target for the development of 'two-compartment' anti-angiogenic/anti-tumor agents, including FGFR selective and nonselective small-molecule tyrosine kinase inhibitors, anti-FGFR antibodies, and FGF ligand traps. Further studies are required to define the correlation between tumor vascularization and activation of the FGF/FGFR system and for the identification of cancer patients more likely to benefit from anti-FGF/FGFR treatments. In addition, advantages and disadvantages about the use of selective versus non-selective FGF inhibitors remain to be elucidated.

Alu-Alu fusion sequences identified at junction sites of copy number amplified regions in cancer cell lines

Alu elements are short, ∼300-bp stretches of DNA and are the most abundant repetitive elements in the human genome. A large number of chromosomal rearrangements mediated by Alu-Alu recombination have been reported in germline cells, but only a few in somatic cells. Cancer development is frequently accompanied by various chromosomal rearrangements including gene amplification. To explore an involvement of Alu-Alu fusion in gene amplification events, we determined 20 junction site sequences of 5 highly amplified regions in 4 cancer cell lines. The amplified regions exhibited a common copy number profile: a stair-like increase with multiple segments, which is implicated in the breakage-fusion-bridge (BFB) cycle-mediated amplification. All of the sequences determined were characterized as head-to-head or tail-to-tail fusion of sequences separated by 1-5 kb in the genome sequence. Of these, 4 junction site sequences were identified as Alu-Alu fusions between inverted, paired Alu elements with relatively long overlapping sequences of 17, 21, 22, and 24 bp. Together with genome mapping data of Alu elements, these findings suggest that when breakages occur at or near inverted, paired Alu elements in the process of BFB cycle-mediated amplification, sequence homology of Alu elements is frequently used to repair the broken ends.

Growth factors as active participants in carcinogenesis: a perspective

Growth factors are low molecular peptides active in the stimulation of cell proliferation and in the regulation of embryonic development and cellular differentiation. Significant progress has been made in developing effective strategies to treat human malignancies with new chemical compounds based on a rationale directed against various components of signaling pathways. Many of these drugs target a growth factor receptor--for instance, in the form of monoclonal antibodies or inhibitors of tyrosine kinases, such as monoclonal antibodies against epidermal growth factor receptors used in treating certain types of breast cancer. Imatinib mesylate [Gleevec]) is an excellent example of mediators of signal transduction, such as tyrosine kinases. Growth factors proper are used to ameliorate various and sometimes fatal side effects of cytotoxic and/or myelosuppressive chemotherapy. Basic characteristics of several growth families are discussed with therapeutic modalities based on growth factor activity or, more often, inhibition of such activity.

Molecular biology of the hst-1 gene

The hst-1 gene (or HSTF1 by human gene nomenclature) was originally identified in our laboratory by an NIH/3T3 focus formation assay using DNA from a human gastric cancer. Sequence analysis predicted the hst-1 product to be a novel growth factor with 30-50% homology with six other heparin-binding growth factors: basic and acidic fibroblast growth factors (FGFs), the int-2 protein, FGF5, the hst-2/FGF6 protein and keratinocyte growth factor (KGF). A recombinant hst-1 protein was synthesized in silkworm cells and found to be a potent heparin-binding mitogen for murine fibroblasts and human vascular endothelial cells. Although hst-1 expression cannot be detected in most cancer cells, including gastric cancers, it is expressed in mouse embryos and in some germ cell tumours. Both hst-1 and int-2 are located on band q13.3 of human chromosome 11 within a distance of 35 kbp; in the mouse genome these two genes are separated by less than 20 kbp. They are differentially transcribed in the F9 mouse teratocarcinoma cell line; hst-1 is expressed in undifferentiated stem cells and int-2 in differentiated endodermal cells. The hst-1 and int-2 genes were coamplified in a variety of cancer cells, most notably in more than 50% of oesophageal cancers.

Aberrant fibroblast growth factor receptor signaling in bladder and other cancers

Fibroblast growth factors (FGFs) are potent mitogens, morphogens, and inducers of angiogenesis, and FGF signaling governs the genesis of diverse tissues and organs from the earliest stages. With such fundamental embryonic and homeostatic roles, it follows that aberrant FGF signaling underlies a variety of diseases. Pathological modifications to FGF expression are known to cause salivary gland aplasia and autosomal dominant hypophosphatemic rickets, while mutations in FGF receptors (FGFRs) result in a range of skeletal dysplasias. Anomalous FGF signaling is also associated with cancer development and progression. Examples include the overexpression of FGF2 and FGF6 in prostate cancer, and FGF8 overexpression in breast and prostate cancers. Alterations in FGF signaling regulators also impact tumorigenesis, which is exemplified by the down-regulation of Sprouty 1, a negative regulator of FGF signaling, in prostate cancer. In addition, several FGFRs are mutated in human cancers (including FGFR2 in gastric cancer and FGFR3 in bladder cancer). We recently identified intriguing alterations in the FGF pathway in a novel model of bladder carcinoma that consists of a parental cell line (TSU-Pr1/T24) and two sublines with increasing metastatic potential (TSU-Pr1-B1 and TSU-Pr1-B2), which were derived successively through in vivo cycling. It was found that the increasingly metastatic sublines (TSU-Pr1-B1 and TSU-Pr1-B2) had undergone a mesenchymal to epithelial transition. FGFR2IIIc expression, which is normally expressed in mesenchymal cells, was increased in the epithelial-like TSU-Pr1-B1 and TSU-Pr1-B2 sublines and FGFR2 knock-down was associated with the reversion of cells from an epithelial to a mesenchymal phenotype. These observations suggest that modified FGF pathway signaling should be considered when studying other cancer types.

Chromosomal imbalances in oral squamous cell carcinoma: examination of 31 cell lines and review of the literature

Classical and molecular cytogenetic analysis, including fluorescence in situ hybridization (FISH) and chromosomal comparative genomic hybridization (CGH), were used to examine genetic changes involved in the development and/or progression of oral squamous cell carcinoma (OSCC). Of 31 OSCC cell lines studied, more than one-third expressed clonal structural abnormalities involving chromosomes 3, 7, 8, 9, and 11. Eleven OSCC cell lines were evaluated using CGH to identify novel genome-wide gains, losses, or amplifications. By CGH, more than half of the cell lines showed loss of 3p, gain of 3q, 8q, and 20q. Further, molecular cytogenetic analyses by FISH of primary tumors showed that the karyotypes of cell lines derived from those tumors correlated with specific gains and losses in the tumors from which they were derived. The most frequent nonrandom aberration identified by both karyotype and CGH analyses was amplification of chromosomal band 11q13 in the form of a homogeneously staining region. Our data suggest that loss of 9p and 11q13 amplification may be of prognostic benefit in the management of OSCC, which is consistent with the literature. The results of this study validate the relationship between these OSCC cell lines and the tumors from which they were derived. The results also emphasize the usefulness of these cell lines as in vitro experimental models and provide important genetic information on these OSCC cell lines that were recently reported in this journal.

Wnt signaling in stem cells and lung cancer

The Wnt signal transduction pathway plays important roles during embryo development, regulating cell proliferation and survival of immature cells. However, its improper function can lead to harmful consequences for humans, such as aberrant cell proliferation and, therefore, cancer. Increasing evidence suggests that stem cells may be the source of mutant cells that cause cancers to develop and proliferate. Wnt signaling has been shown to promote self-renewal in both gut epithelial and hematopoietic stem cells (HSCs) and to trigger critical pathways in carcinogenesis. Although the function of stem cells in solid tumor development is unclear, the Wnt pathway's role in determining the fate and self-renewal potential of cancer stem cells suggests a critical role in carcinogenesis. The development of new inhibitors, such as antibodies or small molecules, to inhibit this pathway may be of great therapeutic utility against cancer.

Wnt2 as a new therapeutic target in malignant pleural mesothelioma

Malignant mesothelioma of the pleura (MPM) is a highly aggressive neoplasm with a poor prognosis and limited treatment options. A better understanding of its pathogenesis is essential to developing alternative therapeutic strategies. We previously demonstrated that the Wnt signaling pathway is activated in MPM through the overexpression of disheveled proteins. To extend our knowledge of Wnt signaling activation in MPM, we performed Wnt-specific microarrays in normal pleura and MPM. We found that the most common event in MPM was the upregulation of Wnt2. We inhibited Wnt2 by siRNA and a monoclonal anti-Wnt2 antibody and analyzed their effects on apoptosis and downstream signaling effectors. We then assessed the antiproliferative effects of the Wnt2 antibody and Alimta, one of the current standard treatments of MPM. We confirmed Wnt2 overexpression at the mRNA and protein level in MPM cell lines and tissues. We then demonstrated that inhibition of Wnt2 by siRNA or a monoclonal antibody induces programmed cell death in MPM cells. We next analyzed the effects of the anti-Wnt2 antibody and of Alimta on MPM cell proliferation. We found that although Wnt2 antibody by itself had less antiproliferative potency than Alimta, the two in combination had substantially more activity than Alimta alone. We thus propose that inhibition of Wnt2 is of therapeutic interest in the development of more effective treatments for MPM.

Recurrent chromosomal rearrangements at bands 8q24 and 11q13 in gastric cancer as detected by multicolor spectral karyotyping

AIM: To identify chromosomal translocations specific to gastric cancer (GC), spectral karyotyping (SKY) analysis was performed on established cell lines and cancerous ascitic fluids.

METHODS: SKY analysis of 10 established cell lines and seven cancerous ascitic fluid samples identified recurrent chromosomal breakpoints and translocations in GC, several of which involved chromosomal loci of oncogenes or tumor suppressor genes.

RESULTS: A total of 630 chromosomal breaks were identified. Chromosome no.8 was the most frequently involved in rearrangements (65 breaks), followed by chromosomes no.11 (53), no. 1 (49), no. 7 (46), no. 13 (37), no. 3 (36), no. 17 (33), and no. 20 (29). Frequent breakpoints were detected in 8q24.1 (30 breaks), 11q13 (29), 13q14 (16), 20q11.2 (14), 7q32 (13), 17q11.2 (13), 18q21 (12), 17q23 (9), 18q11.2 (9). SKY analysis identified a total of 242 chromosomal rearrangements including 190 reciprocal and non-reciprocal translocations. The recurrent combinations of chromosomal bands involved in translocations were 8q24.1 and 13q14 (3 cases), 8q24.1 and 11q13 (3), 11q13 and 17q11.2 (2), and 18q11.2 and 20q11.2 (2). Our study validated the ability of SKY to characterize in detail the chromosomal rearrangements in solid tumors and derived cell lines. Moreover, fluorescence in situ hybridization helped to identify the insertions, translocations, and homogeneously staining regions of MYC and CCND1 gene loci.

CONCLUSION: The non-random co-localization of certain cytogenetic bands suggests the importance of chromosomal translocations in gastric carcinogenesis, by serving as landmarks for the cloning of GC causing genes.

Wnt Signaling in Stem Cells and Non–Small-Cell Lung Cancer

Evidence suggests that stem cells may be the source of mutant cells that cause cancers to develop and proliferate. Wnt signaling has been shown to promote self-renewal in gut epithelial and hematopoietic stem cells and to trigger critical pathways in carcinogenesis. In this review, we highlight the progress in understanding how the Wnt pathway contributes to stem cell maintenance and its role in lung carcinogenesis. Although the function of stem cells in solid tumor development is unclear, the Wnt pathway's role in determining the fate and self-renewal potential of cancer stem cells suggests a critical role in carcinogenesis and that developing drugs to inhibit this pathway may be of therapeutic interest.

Wnt signaling in lung cancer

Wnt signaling has recently emerged as a critical pathway in lung carcinogenesis as already demonstrated in many cancers and particularly in colorectal cancer. We critically discuss in this review the individual components of the Wnt pathway and their role in lung cancer development. We propose that activation of the Wnt-mediated signal occurs in a different manner in lung cancer than in colorectal cancer. In lung cancer, mutations of APC or beta-catenin are rare and the Wnt pathway appears to be activated upstream of beta-catenin. We identified at least three mechanisms of activation: overexpression of Wnt effectors such as Dvl, activation of a non-canonical pathway involving JNK and repression of Wnt antagonists such as WIF-1. The respective relevance of each event and their likely relationship remain unclear. Nevertheless, we propose that many of the studied components of the Wnt pathway may serve as potential targets in the search for therapeutic agents and we can reasonably argue that blockade of Wnt pathway may lead to new treatment strategies in lung cancer.

Genomic rearrangements involving rDNA and centromeric heterochromatin in vulvar epidermoid carcinoma cell line A-431

The cytogenetic and molecular cytogenetic characterization of the human cell line A-431 derived from a vulvar epidermoid carcinoma is presented. A combination of karyotyping, fluorescence in situ hybridization (FISH) with chromosome- and/or region-specific probes, M-FISH, RxFISH, and comparative genomic hybridization (CGH) analysis was used. Six marker chromosomes with rearrangements involving insertions of single or double nucleolar organizing regions (NORs) and/or homogeneously staining regions containing active and overexpressed NORs and regions of centromeric heterochromatin were found: der(6), der(7), der(17), der(21), dic(13;14), and dic(14;18). The chromosomal origin of 14 other marker chromosomes was elucidated. Amplification of the C-MYC oncogene at 8q24 was revealed in two marker chromosomes: dup(8)(q24) and der(15)t(8;15)(q22;p11). Confirming previous reports, amplification of the cyclin D1 gene within an abnormal chromosome 11, that is, der(11)t(7;11)(p15;q21), was also detected. Loss of the TP53 tumor suppressor gene was evidenced over two der(17). Good concordance was found among karyotyping, FISH analysis, and CGH. Although reasons for NOR amplification or ectopic location in the epidermal carcinoma A-431 cell line are not clear yet, our data suggest that these phenomena play a supporting role with regard to other amplified genes. Thus, the A-431 cell line would be an appropriate model to study the different mechanisms involved in human tumorigenesis.

Identification of the CAB2/hCOS16 gene required for the repair of DNA double-strand breaks on a core amplified region of the 17q12 locus in breast and gastric cancers

We previously reported that CAB1 and c-ERBB-2 genes were found to be located in a core amplified region of the 17q12 locus, which is frequently amplified in various cancers. During identification of this core region, CAB2, a human homologue of the yeast COS16 required for the repair of DNA double-strand breaks was cloned. Autofluorescence analysis of cells transfected with its GFP fusion protein demonstrated that CAB2 translocates into vesicles, suggesting that overexpression of CAB2 may decrease intercellular Mn2+ by accumulating it in the vesicles, in the same way as yeast COS16. This is the first report identifying all of the genes on the core amplified region of the 17q12 locus in breast and gastric cancers.

Gene amplification profiling of esophageal squamous cell carcinomas by DNA array CGH

Gene amplification is one of the basic mechanisms that lead to overexpression of oncogenes. DNA array comparative genomic hybridization (CGH) has great potential for comprehensive analysis of both a relative gene-copy number and altered chromosomal regions in cancers, which enables us to identify new amplified genes and unstable chromosomal loci. We examined the amplification status in 32 esophageal squamous cell carcinomas (ESCCs) and 13 ESCC cell lines on 51 frequently amplified loci in a variety of cancers by both DNA array CGH and Southern blot analyses. The 1p34 locus containing MYCL1, 2p24 (MYCN), 7p12 (EGFR), and 12q14 (MDM2) were amplified in one of the 32 cases (3%), and the 17q12 locus (ERBB2) and 8p11 (FGFR1) in two of the 32 cases (6%), while only the 11q13 locus (Cyclin D1, FGF4, and EMS1) was frequently amplified (28%, 9/32), demonstrating this locus to be a major target in ESCCs. One locus, 8q24 (c-MYC) was found to be amplified only in the cell lines. Eight out of 51 loci (15.7%) were found to be amplified in at least one of the 32 primary ESCCs or the 13 ESCC cell lines, suggesting that chromosomal loci frequently amplified in a type of human cancer may also be amplified in other types of cancers. This paper is the first report of an application of DNA array CGH to ESCCs.

K-FGF mediated transformation and induction of metastatic potential involves altered ornithine decarboxylase and S-adenosylmethionine decarboxylase expression--role in cellular invasion

Omithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) expression was investigated in NIH-3T3 fibroblasts that secrete K-FGF. Correlations between altered ODC and SAMDC expression and malignant potential were determined. Increased ODC and SAMDC expression was associated with increased expression of both ODC and SAMDC mRNA and enzyme activity levels. Transcriptional and post-transcriptional regulatory mechanisms were found to account for the increased expression of both ODC and SAMDC. Amplification of the ODC gene also played a role. Correlations between the expression of ODC and the invasion ability of the K-FGF overexpressing cells were also found. Additionally, putrescine, which is a cellular polyamine, was found to play a role in determining the nature of the invasive capacity of the K-FGF overexpressing cells. The results of this study which established correlations between alterations in the expression of ODC and SAMDC, the key rate limiting and regulatory activities in the synthesis of cellular polyamines, and malignant potential as a consequence of K-FGF overexpression supports a model which suggests that growth factor modulation of ODC and SAMDC expression is part of the altered growth regulatory program associated with cellular transformation and malignant progression.

Heparan sulfate proteoglycans as regulators of fibroblast growth factor-2 receptor binding in breast carcinomas

Binding of fibroblast growth factors (FGFs) to their tyrosine kinase-signaling receptors (FGFRs) requires heparan sulfate (HS). HS proteoglycans (HSPGs) determine mitogenic responses of breast carcinoma cells to FGF-2 in vitro. For this study, we examined the role of HSPGs as modulators of FGF-2 binding to FGFR-1 in situ and in vitro. During stepwise reconstitution of the FGF-2/HSPG/FGFR-1 complex in situ, we identified an elevated ability of breast carcinoma cell HSPGs to promote receptor complex formation compared to normal breast epithelium. HSPGs isolated from the MCF-7 breast-carcinoma cell line were then fractionated according to their ability to assemble the FGF-2 receptor complex. All MCF-7 HSPGs are decorated with HS chains similarly capable of promoting FGF-2 receptor complex formation. In this in vitro model, syndecan-1 and syndecan-4 are the cell surface HSPGs contributing most to the complex formation. Relative expression levels of these syndecans in human breast carcinoma tissues correlate well with receptor complex formation in situ, indicating that in breast carcinomas, core protein levels determine FGF-2 receptor complex formation. However, variances in syndecan expression levels do not explain the difference in FGF-2 receptor complex formation between normal and malignant epithelial cells, suggesting that alterations in HS structure occur during malignant transformation.

Fibroblast growth factors

SUMMARY

Fibroblast growth factors (FGFs) make up a large family of polypeptide growth factors that are found in organisms ranging from nematodes to humans. In vertebrates, the 22 members of the FGF family range in molecular mass from 17 to 34 kDa and share 13-71% amino acid identity. Between vertebrate species, FGFs are highly conserved in both gene structure and amino-acid sequence. FGFs have a high affinity for heparan sulfate proteoglycans and require heparan sulfate to activate one of four cell-surface FGF receptors. During embryonic development, FGFs have diverse roles in regulating cell proliferation, migration and differentiation. In the adult organism, FGFs are homeostatic factors and function in tissue repair and response to injury. When inappropriately expressed, some FGFs can contribute to the pathogenesis of cancer. A subset of the FGF family, expressed in adult tissue, is important for neuronal signal transduction in the central and peripheral nervous systems.

Growth factors in glioma angiogenesis: FGFs, PDGF, EGF, and TGFs

It has become well accepted that solid tumors must create a vascular system for nutrient delivery and waste removal in order to grow appreciably. This process, angiogenesis, is critical to the progression of gliomas, with vascular changes accompanying the advancement of these tumors. The cascade of events in this process of blood vessel formation involves a complex interplay between tumor cells, endothelial cells, and their surrounding basement membranes in which enzymatic degradation of surrounding ground substance and subsequent endothelial cell migration, proliferation, and tube formation occurs. It is likely that a host of growth factors is responsible for mediating these key events. To date, a role for Vascular Endothelial Growth Factor (VEGF) in glioma angiogenesis has been convincingly demonstrated. This review explores the contribution of other growth factors--Fibroblast Growth Factors (FGFs), Platelet-Derived Growth Factor (PDGF), Epidermal Growth Factor (EGF), and Transforming Growth Factors (TGFs)--to glioma angiogenesis. These growth factors may influence glioma angiogenesis by directly stimulating endothelial cell proliferation, by mediating the expression of key proteases on endothelial cells necessary for angiogenesis, or by regulating the expression of VEGF and of each other.

Molecular cloning and characterization of human FGF-20 on chromosome 8p21.3-p22

The fibroblast growth factors (FGFs) play important roles in morphogenesis, angiogenesis, tissue remodeling, and carcinogenesis. Human FGF-20 has been cloned and characterized in this study. FGF-20 encodes a 211-amino-acid polypeptide with the FGF-core domain. A strong hydrophobic region was found in the FGF-core domain of FGF-20; however, no typical N-terminal signal sequence was found in FGF-20, just as in FGF-9 and FGF-16. Total amino acid identities are as follows: FGF-20 vs FGF-9, 71.6%; FGF-20 vs FGF-16, 66.2%; FGF-9 vs FGF-16, 72.4%. Phylogenic analysis indicated that FGF-20, FGF-9, and FGF-16 constitute a subfamily among the FGF family. FGF-20 mRNA of 2.4 kb in size was detected in colon cancer cell line SW480 by Northern blot analysis. Lower levels of FGF-20 mRNA were detected in human fetal tissues and primary cancers by cDNA-PCR. The nucleotide sequence of FGF-20 cDNA is split into three parts in the human genome sequence of the chromosome 8p21.3-p22 region (Accession No. AB020858). These results indicate that the FGF-20 gene, located on human chromosome 8p21.3-p22, consists of three exons. Compared with the nucleotide sequence of FGF-20 cDNA determined in this study, one nucleotide deletion and one nucleotide substitution in the putative coding region were identified in human genome sequence AB020858.

11q13 allelic imbalance discriminates pulmonary carcinoids from tumorlets. A microdissection-based genotyping approach useful in clinical practice

Pulmonary tumorlets are minute neuroendocrine cell proliferations believed to be precursor lesions to pulmonary carcinoids. Little is known of their molecular pathogenesis because of their small size. Using tissue microdissection, we evaluated 11q13 region allelic imbalance in the pathogenesis of pulmonary tumorlet/carcinoid lesions. The int-2 gene was selected because of its chromosomal location at 11q13 in close proximity to MEN1, a tumor suppressor gene frequently mutated in familial forms of neuroendocrine cancer. Three cohorts of patients were studied: subjects with typical carcinoid tumors and coexisting tumorlets (n = 5), typical carcinoids without tumorlets (n = 6), and tumorlets alone without carcinoid lesions (n = 5). A total of 11 carcinoids and 11 tumorlets were microdissected from 4-micrometer-thick histological sections. Genotyping was designed to detect allelic imbalance of the int-2 gene and involved DNA sequencing of two closely spaced deoxynucleotide polymorphisms. Subjects shown to be informative were evaluated for allelic imbalance in tumorlet/carcinoid tissue. Eight of 11 (73%) carcinoids manifested allelic, in contrast to only one of 11 (9%) of tumorlets. Int-2 allelic imbalance was significantly associated with carcinoid tumor formation (P < 0.01). In patients having both carcinoid tumors and tumorlets, the latter showed allelic balance and were thus discordant in genotype with coexisting carcinoid excluding pathogenesis of tumorlets from intramucosal spread from carcinoid tumors. Int-2 allelic imbalance was shown to be an early event in carcinoid tumor formation by virtue of the absence of allelic imbalance for other common cancer-related gene disturbances involving 11p13 (Wilms' tumor), 3p25 (von-Hippel-Lindau), and 17p13 (p53). Demonstration of 11q13 allelic imbalance by microdissection/genotyping may be a useful discriminatory marker for pulmonary neuroendocrine neoplasia.

Spectrum of transforming sequences detected by tumorigenicity assay in a large series of human neoplasms

We here summarize the analysis of 126 DNA samples from patients with hematopoietic neoplasias and solid tumors and from various tumor cell lines that were screened in the tumorigenicity assay. Thirty-eight samples were able to induce tumors after transfection in NIH/3T3 cells and injection into nude mice. Southern-blot analysis with a panel of oncogene probes revealed human ras genes in the vast majority of cases (25 N-ras, 2 K-ras, 1 H-ras) but also activated FGF4, dbl, ret and mas genes respectively. DNA samples from the 6 remaining transfectants were cloned into EMBL-3 phages and screened with a human specific repetitive Alu probe. Direct hybridization of a transfectant cDNA library allowed cloning of the ufo oncogene. Application of the exon-trapping technique to alu-positive phage DNA from the other transfectants enabled us to isolate tre, cot, B-raf, p85beta/HUMORF8 and a novel oncogene.

Prolactinomas express human heparin-binding secretory transforming gene (hst) protein product: marker of tumour invasiveness

BACKGROUND AND OBJECTIVE

We have shown previously that heparin-binding secretory transforming gene (hst) overexpression in rat pituitary cells mediates lactotroph tumour growth and stimulates PRL transcription, and that transforming sequences of the gene, which encode fibroblast growth factor-4 (FGF-4), are expressed in human prolactinomas. To further determine the role of hst in human PRL-secreting adenoma pathogenesis we studied the presence of hst protein in these tumours and other types of human pituitary adenoma.

PATIENTS AND DESIGN

Pituitary adenoma tissue samples were obtained at surgery from 14 patients with PRL-secreting adenomas, 5 patients with GH-secreting tumours, 3 with ACTH-secreting, and 13 patients with nonfunctioning tumours. Two normal pituitary tissue specimens were also studied. Clinical data, including tumour invasiveness assessed by preoperative MRI studies, were available. For hst protein immunolocalization, tumour frozen sections were immunostained with antihuman FGF-4 antibody. Immunoperoxidase staining for the proliferation-related nuclear antigen Ki-67 was performed using MIB-1 monoclonal antibody.

RESULTS

Normal anterior pituitary cells did not contain immunoreactive hst protein. Lactotrophs in five of 14 prolactinomas (36%) stained strongly for hst compared with immunoreactive pituicytes in only one of 21 nonfunctioning, GH-, and ACTH-secreting adenomas (P = 0.05). Immunoreactive hst in adenoma cells was detected in 3 of 5 invasive prolactinomas, and in 2 of 9 noninvasive PRL-cell adenomas. Immunostaining for the proliferation-related antigen Ki-67 showed a higher proliferation index in hst-positive adenomas (3.94 + 0.85%) as compared with those immunonegative for hst (1.98 + 0.7%; P = 0.05).

CONCLUSIONS

hst protein may be directly involved in prolactinoma development or progression, particularly in invasive tumours, probably due to the growth promoting effects of FGF-4.

Gene amplification of int-2 and erbB in human esophageal cancer: relationship to clinicopathological variables

Gene amplification is a relatively frequent event in human malignant tumors and is believed to play an important role in tumor progression. The int-2 and erbB genes are amplified more frequently than any other genes in human esophageal cancer. In order to investigate the correlation between these two proto-oncogenes and the clinical behavior of esophageal cancer, we examined DNA amplification of int-2 and erbB and analyzed their relationship to clinicopathological variables. Genomic DNA was extracted from 21 esophageal squamous carcinomas and normal esophageal mucosa, as well as from 4 metastatic tumors. We used Southern blot analysis for detection of gene amplification. Amplification of int-2 was observed in 13 of 21 cases (62%) and in all the metastatic tumors (4/4; 100%). We found a significant correlation between amplification of int-2 and the length of the primary lesion. Amplification of erbB was detected in 3 of 18 patients (17%). All patients who showed amplification of erbB also demonstrated amplification of int-2. These results suggest that amplification of int-2 or neighboring genes on 11q may participate in tumor progression and metastasis in patients with esophageal squamous cancer.

Biology of esophageal cancer and the role of combined modality therapy

1. The biology of esophageal cancer involves multifactorial environmental and genetic events. 2. The understanding of the clinical significance of molecular markers is rapidly evolving. 3. Combined-modality approaches should still include surgery in good performance status (ECOG scale < or = 2) patients. 4. Neoadjuvant chemoradiation is probably better than surgical resection alone for patients with potentially curable disease, but only validation of this approach by CALGB-9781 can justify this as a new "proven" standard-of-care in the United States. 5. A pathologic complete response to neoadjuvant therapy is the strongest predictor of long-term survival. 6. 5-FU, by either short course or protracted continuous infusion, comprises the backbone of combination chemotherapy in combined-modality design. 7. Radiation therapy should be given at standard 1.8 to 2 Gy/fraction without a scheduled break. 8. Only by enrolling sufficient numbers of patients in prospective clinical trials will clinicians be able to further define the optimal sequencing and actual necessity of each individual component of combined-modality therapy.

Molecular cloning of human GRB-7 co-amplified with CAB1 and c-ERBB-2 in primary gastric cancer

Many amplified-chromosome regions in human cancers have been identified, while there are only a limited number of reports for amplified genes in a single amplicon. We recently isolated four cDNA clones, A39, B47, C51, and CAB1, from 500 kilobases of yeast artificial chromosome DNA containing the c-ERBB-2 gene. B47 consisted of 615 base pairs and had about 85% homology with the corresponding sequence of mouse Grb-7. We report here the structure of human GRB-7 cDNA, and we report that the amounts of mRNA for c-ERBB-2, CAB1, and GRB-7 were elevated in concordance with the amplification.

Possibilities of a viral etiology for human breast cancer. A review

Previous studies related mouse mammary tumor virus (MMTV) to human breast cancer. However, the presence of human endogenous retroviruses (HERs) confounded these results. We selected a 660-bp sequence of the MMTV env gene with low homology to HER (or any other known gene) and searched for a sequence homologous to it, using the polymerase chain reaction (PCR). The 660-bp sequence was detected in 131 (39%) of 335 unselected breast cancers, in 2 (6.9%) of 29 fibroadenomas, and in 2 (1.65%) of 121 normal breast specimens. The sequence was not present in normal tissues, or in other human cancers or cell lines. Cloning and sequencing of the 660-bp sequence revealed that it is 95-98% homologous to MMTV env gene, but not the known HERs or other viral or human gene. Southern blot hybridization using labeled cloned sequences demonstrated that the 660-bp sequence was present in very low copy number as a 6-8 kb EcoRI fragment only in breast cancer samples and in some of the human breast cancer cell lines that were positive by PCR. Preliminary experiments using reverse transcriptase (RT)-PCR indicated that expression of the 660-bp sequence can be detected in 65% of the positive tumors. We were also able to identify in breast cancer DNA a segment of 1.6 kb comprising LTR and env gene sequences, which are homologous to MMTV, but not to the HERs. The origin of the MMTV-like sequences in tumor DNA could be the result of integrated MMTV-like sequences derived from a human mammary virus.

Detection of 11q13 amplification as the origin of a homogeneously staining region in small cell lung cancer by chromosome microdissection

Chromosomal homogeneous staining region (hsr), which is a cytogenetic indication of gene amplification, was found in the pleural effusion (BHII) of a patient with small cell lung cancer (SCLC) after failure of multiple drug treatments. Amplification of band 11q13 was identified as the origin of the hsr by means of chromosomal microdissection combined with G-banding, DNA amplification by polymerase chain reaction, and fluorescence in situ hybridization (micro-FISH). In situ hybridization with the biotin-labeled DNA probe generated from the hsrs of BHII to the cell line BHI, which was established from the lymph node metastasis prior to chemotherapy, revealed the preexistence of 11q13 amplification. This ruled out the possibility of therapeutic induction of the 11q13 amplification. However, the hsr-bearing marker chromosomes were identified by the micro-FISH approach as der(21)(Xqter-->Xq24::hsr(11)(q13)::21p11-->21qter+ ++) in BHII but as der(11)t(3;11)(q21;q13)hsr(11)(q13) in BHI. This suggests that 11q13 DNA sequence amplification may occur first and is then followed by various types of structural rearrangements. FISH analysis with INT2/FGF3 and HST1/FGF4 probes revealed that these protooncogenes were coamplified in the hsrs of BHI and BHII. The results obtained suggest that 11q13 amplification and the successive structural rearrangement may play an important role in the progression of the disease and its therapeutic response.

PRAD1/Cyclin D1 gene overexpression in mantle cell lymphoma

The t(11;14) (q13;q32) translocation and its molecular counterpart Bcl-1 rearrangement are consistent features of mantle cell lymphoma (MCL). This translocation activates the PRAD1/cyclin D1 gene that is considered to be the Bcl-1 oncogene. PRAD1/cyclin D1 gene overexpression is closely associated with MCL. The PRAD1/cyclin D1 protein is localized to the nucleus, and the strong correlation between PRAD1/cyclin D1 and MCL is also found in the protein level. This finding indicates that PRAD1/cyclin D1 expression is a highly specific and sensitive molecular marker for MCL. This gene may function as an oncogene in the malignant transformation of cells.

Translocation t(8;16)(p11;p13) in acute non-lymphocytic leukemia: report on two new cases and review of the literature

Two new cases of t(8;16)(p11;p13) in acute nonlymphocytic leukemia (ANLL) are described. These two patients in addition to the 34 previously described, showed a striking association with myelomonocytic (M4) or monocytic (M5) leukemia, extramedullary infiltration, erythrophagocytosis and disseminated intravascular coagulation. One of our patients showed a TCRbeta gene rearrangement. Alltogether 36 cases of t(8;16) ANLL have been documented until today. We here review their clinical and cytogenetic features.

Heparin-binding secretory transforming gene (hst) facilitates rat lactotrope cell tumorigenesis and induces prolactin gene transcription

We have shown previously that human prolactinomas express transforming sequences of the heparin-binding secretory transforming gene (hst) which encodes fibroblast growth factor-4 (FGF-4). To elucidate the role of hst in pituitary tumorigenesis we treated primary rat pituitary and pituitary tumor cell cultures with recombinant FGF-4 and also stably transfected pituitary cell lines with full-length human hst cDNA. Transfectants were screened for hst mRNA expression and FGF-4 production. FGF-4 (0.1-50 ng/ml) caused a dose-dependent 2.5-fold increase of prolactin (PRL) secretion (P < 0.001) in GH4 cells and up to 60% (P < 0.05) in primary cultures, while decreasing growth hormone release (P < 0.001). GH4 hst transfectants displayed markedly enhanced basal PRL secretion (threefold, P < 0.001) and also proliferated faster (P < 0.001). FGF-4 treatment of wild-type GH4 cells, transiently transfected with an expression construct (rPRL.luc) containing a luciferase reporter driven by the rPRL promoter, resulted in a dose-dependent increase of up to 3.3-fold in PRL transcriptional activity. Tumors derived from in vivo subcutaneous injection of GH4 hst-transfected cells strongly expressing FGF-4 grew more aggressively as assessed by histologic invasiveness and proliferating cell nuclear antigen staining (P < 0.01). The results indicate that hst overexpression mediates lactotrope tumor growth and potently stimulates PRL synthesis. Thus, hst may directly facilitate prolactinoma development via paracrine or autocrine action of its secreted protein, FGF-4.

Overexpression and localization of cyclin D1 mRNA and antigen in esophageal cancer

We examined the expression of cyclin D1 mRNA in two human carcinoma cell lines (A431 and TT) and 17 specimens of esophageal cancer with in situ hybridization. Cyclin D1 mRNA was overexpressed in the cytoplasm of cancer cells that showed cyclin D1 gene amplification by Southern blot hybridization. Cyclin D1 antigen was overexpressed in the nucleus of these cancer cells. The distribution of cyclin D1 mRNA-positive cells was similar to that of cyclin D1 antigen-positive cells in the cancer tissues. We then attempted to correlate overexpression of cyclin D1 antigen and prognosis, by using 55 formalin-fixed, paraffin-embedded specimens of esophageal cancer. The overall 5-year survival of patients with strongly staining tumors was significantly lower than that of patients with weakly or nonstaining tumors (7 versus 59%; P < 0.01). There was no significant correlation between cyclin D1 expression and other clinicopathological factors. These results suggest that cyclin D1 may play an important role in carcinogenesis and that cyclin D1 overexpression may be a useful prognostic factor in esophageal cancer.

Pathologic prognostic factors for gastrointestinal cancer

Numerous clinicopathologic factors have been reported to have prognostic significance for gastrointestinal cancer. Many problems, however, confront the surgeon assessing the extent of disease and the clinical and molecular pathologist distinguishing differences in tumor differentiation, behavior, and defining important prognostic markers of cancer. This review assesses current pathologic prognostic variables of gastric and colorectal cancer that have been reported to influence survival.

Chromosome 11q13 markers and D-type cyclins in breast cancer

One in six primary human breast cancers has DNA amplification centered on the cyclin D1 gene (CCND1) on chromosome 11q13. This genetic abnormality is preferentially associated with estrogen-receptor positive tumors and may define a sub-class of patients with an adverse prognosis. Although CCND1 has the credentials of a cellular oncogene, being a target for chromosomal translocation and retroviral integration, the 11q13 amplicon encompasses several other markers and CCND1 is not the only candidate for the key gene on the amplified DNA. To assess their relative importance, we have constructed a physical map of the amplified DNA and compared the extent and frequency of amplification across the region. Since it is likely that the gene providing the selective force for amplification will be expressed at elevated levels, we have also examined expression of both RNA and protein. By these criteria, cyclin D1 remains the strongest candidate for the key oncogene on the amplicon and we are currently investigating the functional consequences of its over-expression.

The genetics of human limb development

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Monoclonal antibodies against hst-1 gene product

Four monoclonal antibodies (MAbs) against the hst-1 gene product (hst-1 protein) were obtained by a somatic cell hybridization technique. The recognition sites of these MAbs designated HS-131, HS-210, HS-233 and HS-276 on the hst-1 protein were evaluated by competitive binding assay with synthetic polypeptides. HS-131 MAb and HS-276 MAb recognize the epitope located within the 59-73 and the 197-206 amino acid sequences, respectively. The epitopes recognized by HS-210 and HS-233 MAbs could not be determined, but these MAbs showed neutralizing activity against hst-1 protein. Using HS-131 and HS-233 MAbs, a sensitive sandwich enzyme immunoassay (sandwich EIA) has been developed. The assay sensitivity was 1.2-2.5 pg/well of hst-1 protein. Acidic and basic fibroblast growth factors were not cross-reactive up to a concentration of 1 microgram/ml.

Co-amplification of the gene for parathyroid hormone-related protein (PTHRP) and KRAS2 in a human lung cancer cell line

Parathyroid hormone-related protein (PTHRP) is expressed in a large number of tumors and is the mediator of parathyroid hormone-like effects seen in humoral hypercalcemia of malignancy. The gene coding for PTHRP has been localised to the short arm of chromosome 12. This is at the same region as the oncogene KRAS2, and amplification of KRAS2 has previously been found in human lung cancer. The BEN cell line which is known to express PTHRP was established from a patient who had squamous cell carcinoma of the lung with hypercalcemia. Cytogenetic analysis of the BEN cell line revealed a very complex karyotype with many marker chromosomes. Chromosomal in situ hybridization with biotinylated DNA probes visualized by a biotin-streptavidin-polyalkaline-phosphatase complex was used to analyse two dicentric marker chromosomes containing homogeneously staining regions (hsr) in BEN. The hsr were found to contain amplified PTHRP and KRAS2 at levels of 30-fold and 14-fold per cell, respectively. The higher level of amplification of the PTHRP gene would suggest that PTHRP is the target gene of amplification in the amplicon. This is the first report of gene amplification of PTHRP and in addition its co-amplification with KRAS2.

Characterization of two 11q23.3-11q24 deletions and mapping of associated anonymous DNA markers

Translocations in bands 11q23.3-11q24 are associated with several human cancers, including acute lymphoid and acute myeloid leukemias (AML) and Ewing's sarcoma. We have characterized two independent deletions in this region, one derived from a patient with AML who previously had a T-cell lymphoma, and another from a Wilms' tumor patient. Cytogenetic analysis of the ML-2 cell line established from the malignant cells of the AML patient indicated that one chromosome 11 homolog had an interstitial deletion, del(11) (q23q24), and the remaining homolog was involved in a recurring translocation, t(6;11) (q27;q23). According to karyotype analysis on the Wilms' tumor patient (EH), one chromosome 11 was normal and the other carried an interstitial deletion at 11q23.3-11q25. Somatic cell hybrids segregating the EH deletion (EHR4) and the ML-2 deletion (MLR4) have been isolated. The EH deletion is distal to the MLL probe recently associated with 11q23.3 leukemia breakpoints (Ziemin-van der Poel et al.: Proc Natl Acad Sci USA 88:10735-10739, 1991). The ML-2 deletion could involve the MLL gene at a point distal to other breakpoints within MLL. Both deletions include the Ewing's sarcoma breakpoint at 11q24.1. By Southern blot analysis we identified three anonymous DNA markers (D11S272, D11S273, and D11S219) and the ETS/oncogene, which map within each deleted region. These markers are conserved based on zoo blot analysis, and they are valuable for physical mapping and genetic characterization of a region that may code for gene products associated with growth control and tumor suppression in a variety of cancers.

Amplified region of chromosome band 11q13 in breast and squamous cell carcinomas encompasses three CpG islands telomeric of FGF3, including the expressed gene EMS1

DNA markers that map within the karyotypically defined band q13 on human chromosome 11 are amplified in a subset of mammary and squamous cell carcinomas. It is assumed that the amplified DNA includes a critical gene (or genes) whose overexpression provides a selective force in the development of the tumor. To help identify such genes, we have begun to construct a physical map of CpG islands in the region, making use of a squamous cell carcinoma cell line (UMSCC2) in which the 11q13 region is amplified 11-fold. We previously described the proximal end of this amplicon and the order of markers extending approximately 800 kb centromeric of the FGF3 locus (formerly INT2). We now report the use of chromosome jumping techniques to define additional CpG islands that lie distal to FGF3. These map within the amplified region in UMSCC2 cells and the most telomeric corresponds to the EMS1 gene. The data imply that the amplified DNA in UMSCC2 cells extends for over 1,500 kb and includes at least 7 potential genes. EMS1 and CCND1 (formerly PRAD1), the best candidates for the key gene on the 11q13 amplicon, are > or = 800 kb apart.

Chromosomal location and structure of amplicons in two human cell lines with coamplification of c-myc and Ki-ras oncogenes

Gene amplification is a major mechanism through which oncogenes and genes responsible for drug resistance are overexpressed in neoplastic cells, and several models for structure of amplified units (amplicons) are postulated. In order to identify consistent changes associated with oncogene amplification, we analyzed chromosomal location and physical distance of amplicons of two independent human cell lines that have coamplified c-myc and Ki-ras oncogenes. In one cell line, KHC287, amplified c-myc genes were localized in two chromosomes and Ki-ras in three chromosomes. One marker chromosome was almost entirely encompassed by both amplified genes. In the other cell line, Lu-65, both of the amplified genes shared the same locus, on chromosome 12q+. The two genes, however, are more than 1500 kb apart in both cell lines. The above findings indicate that two different amplified genes became associated on one chromosome in two independent cell lines. This suggests that a common mechanism is associated with chromosomal rearrangements affecting different amplified genes.

Steroid hormone receptor immunohistochemistry and amplification of c-myc protooncogene. Relationship to disease-free survival in breast cancer

BACKGROUND

It is important to develop parameters that aid in prognosticating which patients with breast cancer are more likely to have a rapid disease course and therefore might benefit from early aggressive therapies.

METHODS

Specimens from two groups of women, deliberately selected because their clinical courses differed greatly, were studied to detect amplification of the protooncogenes c-myc, int-2, and C-erbB-2/neu by slot-blot assay, the estrogen receptor (ER), and the progesterone receptor (PR) by both biochemical and immunohistochemical procedures (ERICA and PRICA). One group of 50 patients had a prolonged disease-free interval after initial surgery (mean, 6.4 years); the other group of 52 women had had rapid disease recurrence (mean, 1.4 years) or progression (5 patients died of disease within 1 year of diagnosis). The patients were selected from 1700 consecutively accessioned cases if they fit the study criteria and sufficient tissue was available for oncogene hybridization studies.

RESULTS

The two groups differed statistically by stage, number of involved axillary lymph nodes, ERICA and PRICA results (P = 0.001), and amplification of c-myc (P = 0.003). The percentage of patients with rapid disease recurrence and progression increased from 0-93% when risk factors changed from best case (ERICA and PRICA results, positive; c-myc, not amplified; and axillary nodes, not involved) to worst case (ERICA and PRICA findings, negative; c-myc, amplified; and axillary nodes, involved).

CONCLUSIONS

Women with these worst-case parameters were more likely to have a recurrence sooner and rapidly progressive disease. They might benefit from early aggressive therapeutic measures.

Establishment of a highly sensitive and specific exon-trapping system

We have established a highly sensitive and specific exon-trapping system (SETS) with a specific plasmid vector in which an exon in a given DNA segment is identified by its ability to remain as a mature mRNA after splicing. The SETS provides us with the isolation of possible exons rapidly and easily from DNA fragments in chromosomal regions of more than 300 kilobase pairs. Genomic DNA fragments were partially digested and subsequently cloned into plasmid pMHC2, an exon-trapping vector we have constructed. These constructs were transfected into COS-7 cells, and consequent RNA transcripts were spliced in the cells. The resulting mature mRNA was harvested and amplified by using reverse transcription-PCR. Possible exons can be recognized by the sizes of PCR products and cloned into a plasmid vector. The SETS provides a direct means of cloning exons from genomic DNA of more than 300 kilobase pairs within a short period of time. Using this system, we have screened 300-kilobase-pair genomic DNA segments derived from human chromosome 11q13. Human chromosome 11q13 may contain genes responsible for human cancers, because DNA amplification is observed in several malignant tumors. We have successfully identified exon 2 of the HST1 gene and additional transcribed sequences.

Elimination of extrachromosomally amplified MYC genes from human tumor cells reduces their tumorigenicity

Oncogene amplification has been observed in a broad spectrum of human tumors and has been associated with a poor prognosis for patients with several different types of malignancies. Importantly, at biopsy, the amplified genes localize to acentric extrachromosomal elements such as double-minute chromosomes (DMs) in the vast majority of cases. We show here that treatment of several human tumor cell lines with low concentrations of hydroxyurea accelerates the loss of their extrachromosomally amplified oncogenes. The decreases in MYC copy number in a human tumor cell line correlated with a dramatic reduction in cloning efficiency in soft agar and tumorigenicity in nude mice. No effect on gene copy number or tumorigenicity was observed for a closely related cell line containing the same number of chromosomally amplified MYC genes. One step involved in the accelerated loss of extrachromosomal elements is shown to involve their preferential entrapment of DMs within micronuclei. The data suggest that agents that accelerate the loss of extrachromosomally amplified genes could provide valuable tools for moderating the growth of a large number of human neoplasms.