K-sam, an amplified gene in stomach cancer, is a member of the heparin-binding growth factor receptor genes

Epigenetically controlled fibroblast growth factor receptor 2 signaling imposes on the RAS/BRAF/mitogen-activated protein kinase pathway to modulate thyroid cancer progression

Fibroblast growth factor (FGF) signals play fundamental roles in development and tumorigenesis. Thyroid cancer is an example of a tumor with nonoverlapping genetic mutations that up-regulate mitogen-activated protein kinase (MAPK). Here, we show that FGF receptor 1 (FGFR1), which is expressed mainly in neoplastic thyroid cells, propagates MAPK activation and promotes tumor progression. In contrast, FGFR2 is down-regulated in neoplastic thyroid cells through DNA promoter methylation. Reexpression of FGFR2 competes with FGFR1 for the immediate substrate FGFR substrate 2 to impede signaling upstream of the BRAF/MAPK pathway. These data unmask an epigenetically controlled FGFR2 signal that imposes precisely on the intragenically modified BRAF/MAPK pathway to modulate thyroid cancer behavior.

Deciphering the underlying genetic and epigenetic events leading to gastric carcinogenesis

Gastric cancer is a common aggressive malignancy. Although its incidence shows considerable variation among different countries, gastric cancer is still a major health problem worldwide. The causes of stomach cancer are not completely understood. What is clear is that gastric cancer is a multi-stage process involving genetic and epigenetic factors. This review is an in-depth study of the known genetic and epigenetic processes in the development of this tumor, and delineates possible approaches in gene and epigenetic therapy.

Aberrant hypermethylation of the FGFR2 gene in human gastric cancer cell lines

We have previously shown that fibroblast growth factor receptor 2 (FGFR2) plays an important role in gastric carcinogenesis. In this study, we assessed DNA methylation status in the promoter region of FGFR2 gene in gastric cancer cell lines, and indicated that this region was highly methylated, compared with FGFR2-expressing gastric cancer cell lines. Moreover, the restoration of FGFR2 expression by treating methylated cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine strongly suggests that the loss of FGFR2 expression may be due to the aberrant hypermethylation in the promoter region of the FGFR2 gene. Thus, our results suggest that the epigenetic silencing of FGFR2 through DNA methylation in gastric cancer may contribute to tumor progression.

A novel molecular targeting compound as K-samII/FGF-R2 phosphorylation inhibitor, Ki23057, for Scirrhous gastric cancer

BACKGROUND & AIMS

Scirrhous gastric carcinoma carries the highest mortality of all gastric cancers. The poor prognosis is reported to be associated with K-samII amplification, which encodes fibroblast growth factor receptor type 2 (FGF-R2). Ki23057, a newly developed small molecule-acting K-samII/FGF-R2 autophosphorylation inhibitor, is a tyrosine kinase inhibitor that competes with adenosine triphosphate for the binding site. The aim of the current study is to clarify the possibility of molecular target therapy with Ki23057 for treating scirrhous gastric cancer.

METHODS

Five human gastric cancer cell lines were used. OCUM-2MD3 and OCUM-8 were derived from scirrhous carcinomas. MKN-7, MKN-45, and MKN-74 cells were derived from nonscirrhous carcinomas. In vitro effects of Ki23057 on cell growth were determined by calculating the number of cancer cells. The influences of Ki23057 on the mitogen-activated protein kinase and phosphatidylinositol 3 kinase signaling pathways and the apoptosis pathway in the gastric cancer cells were also examined. For in vivo experiments, the Ki23057 was administered orally to mouse models of peritoneal dissemination.

RESULTS

K-samII amplification was found in OCUM-2MD3 and OCUM-8 cells but not in MKN-7, MKN-45, or MKN-74 cells. Ki23057 significantly inhibited the proliferation of scirrhous cancer cells but not nonscirrhous gastric carcinoma cells. Ki23057 decreased phosphorylation of K-samII/FGF-R2, extracellular signal-regulated kinase, and Akt and increased apoptosis in scirrhous cancer lines. The oral Ki23057 administration significantly (P < .001) prolonged survival of mice with peritoneal dissemination following injection of OCUM-2MD3 scirrhous cancer cells.

CONCLUSIONS

A novel K-samII/FGF-R2 phosphorylation inhibitor, Ki23057, appears therapeutically promising in scirrhous gastric carcinoma with K-samII amplification.

Cytoarchitecture of fibroblast growth factor receptor 2 (FGFR-2) immunoreactivity in astrocytes of neurogenic and non-neurogenic regions of the young adult and aged rat brain

Fibroblast growth factors (FGFs) are polypeptides that exert diverse biological effects on many cell types and tissues during embryogenesis and adulthood. In the adult brain, FGF-2 is primarily expressed by astrocytes and select groups of neurons. It has been shown that FGF-2 is neuroprotective and can stimulate proliferation of NSCs in neurogenic regions of the adult mammalian brain. Cellular responses to FGFs are mediated through membrane-spanning tyrosine kinase receptors in conjunction with low affinity binding to heparin sulfate proteoglycans. Four FGF receptors (FGFR1-4) have been cloned and characterized to date. In this study, we describe the anatomical distribution of FGFR-2 in young and aged rat brains. We demonstrate that the olfactory bulb, hippocampus, and cerebellum display the most robust FGFR-2 expression and observed age-related decrease in FGFR-2 levels in some but not all brain regions. In addition, we identified astrocytes as the primary source of FGFR-2 expression using immunofluorescence confocal microscopy. The astrocyte populations in the neurogenic areas, the subventricular zone (SVZ) and the subgranular zone (SGZ) of the dentate gyrus, express high levels of FGFR-2 protein, which points to its possible involvement in neurogenesis. We also explored the role of FGFR-2 in response to perforant pathway lesion and observed enhanced FGFR-2 expression by astrocytes surrounding the lesion. Thus, FGF-2 biological effects on astrocytes appear to be mediated through FGFR-2-dependent mechanisms, and this may provide an indirect route by which FGF-2 acts on neuronal populations.

Keratinocyte growth factor expression and activity in cancer: implications for use in patients with solid tumors

Keratinocyte growth factor (KGF) is a locally acting epithelial mitogen that is produced by cells of mesenchymal origin and has an important role in protecting and repairing epithelial tissues. Use of recombinant human KGF (palifermin) in patients with hematologic malignancies reduces the incidence and duration of severe oral mucositis experienced after intensive chemoradiotherapy. These results suggest that KGF may be useful in the treatment of patients with other kinds of tumors, including those of epithelial origin. However, its application in this context raises issues that were not pertinent to its use in hematologic cancer because epithelial tumor cells, unlike blood cells, often express the KGF receptor (FGFR2b). Thus, it is important to examine whether KGF could promote the growth of epithelial tumors or protect such tumor cells from the effects of chemotherapy agents. Analyses of KGF and FGFR2b expression in tumor specimens and of KGF activity on transformed cells in vitro and in vivo do not indicate a definitive role for KGF in tumorigenesis. On the contrary, restoring FGFR2b expression to certain malignant cells can induce cell differentiation or apoptosis. However, other observations suggest that, in specific situations, KGF may contribute to epithelial tumorigenesis. Thus, further studies are warranted to examine the nature and extent of KGF involvement in these settings. In addition, clinical trials in patients with solid tumors are underway to assess the potential benefits of using KGF to protect normal tissue from the adverse effects of chemoradiotherapy and its possible impact on clinical outcome.

Cellular and molecular aspects of gastric cancer

Gastric cancer remains a global killer with a shifting burden from the developed to the developing world. The cancer develops along a multistage process that is defined by distinct histological and pathophysiological phases. Several genetic and epigenetic alterations mediate the transition from one stage to another and these include mutations in oncogenes, tumour suppressor genes and cell cycle and mismatch repair genes. The most significant advance in the fight against gastric caner came with the recognition of the role of Helicobacter pylori (H pylori) as the most important acquired aetiological agent for this cancer. Recent work has focussed on elucidating the complex host/microbial interactions that underlie the neoplastic process. There is now considerable insight into the pathogenesis of this cancer and the prospect of preventing and eradicating the disease has become a reality. Perhaps more importantly, the study of H pylori-induced gastric carcinogenesis offers a paradigm for understanding more complex human cancers. In this review, we examine the molecular and cellular events that underlie H pylori-induced gastric cancer.

Differential signal transduction of alternatively spliced FGFR2 variants expressed in human mammary epithelial cells

Gene amplification and protein overexpression of fibroblast growth factor receptor 2 (FGFR2) characterize the SUM-52 breast cancer cell line developed in our laboratory. SUM-52 cells express nine distinct alternatively spliced isoforms of FGFR2. Among these isoforms are two otherwise identical FGFR2 variants that express either the C1 or C3 carboxyl terminus. FGFR2-C3 variants are not normally expressed by human mammary epithelial (HME) cells, and we have shown that overexpression of FGFR2-C3 in HME cells results in potent transformation. In particular, FGFR2-C3 expression leads to robust levels of constitutively tyrosine phosphorylated FRS2 in the absence of ligand stimulation. In contrast, overexpressed FGFR2-C1 requires constant stimulation with exogenous keratinocyte growth factor (KGF) to mimic the signaling capability of FGFR2-C3. However, activation of FRS2 that results from KGF-stimulated FGFR2-C1 signaling is transient and is associated with a mobility shift of FRS2 not observed when this signaling molecule is activated by the C3 isoform of FGFR2. Mutation of the only tyrosine phosphorylated site present in the C1 terminus and absent from C3, Tyr769, did not yield a receptor that rivaled the potent signaling of FGFR2-C3. We therefore conclude that aberrant expression of alternatively spliced isoforms of FGFR2 with the C3 carboxyl terminus in the SUM-52 breast cancer cells results in sustained activation of signal transduction leading to transformation.

Pathology and molecular biology of gastric cancer

Several attempts to classify gastric cancer (GCA) have been made over the past decades. Most successful, and widely used, is the classification by Laurén, which distinguishes, by microscopical morphology alone, two main cancer pathogeneses, diffuse (DGCA) and intestinal (IGCA) subtypes, which appear clearly as dissimilar clinical and epidemiological entities. Here we review the main differences in epidemiology, histopathology, and molecular pathology of the two main subtypes of gastric carcinomas based on Laurén classification. In clinical practice, however, clinical staging, particularly in predicting the survival, still remains superior to all classifications of gastric cancer independent of cancer type. The existence of local precursor lesions or conditions of IGCA tumours, i.e. Helicobacter pylori gastritis, atrophic gastritis (AG), intestinal metaplasia (IM), adenoma, dysplasia, and intramucosal neoplasia, is firmly established. The links of DGCA with intestinal-type epithelium, AG or IM are poor, or do not exist. So far, H. pylori gastritis is the only universal precursor condition for DGCA. It implies that AG and achlorhydria are of minor significance and infrequent in the development of DGCA but are important steps in that of IGCA. Despite an increasing body of data, the overall view on molecular pathology of GCA remains fragmentary. No consistent differences in the molecular pathology of GCA subtypes to meet the Laurén classification have been established. With the exception of TP53, no gene mutation occurring regularly in both histological types of GCA has been reported. Chromosomal aberrations and loss of heterozygosity seem to be non-specific and do not follow any consistent route in the progression of GCA. Microsatellite instability is more commonly found in IGCA than in DGCA. The present epigenetic data suggest that most of the decrease (or loss) of gene expression may be explained by promoter hypermethylation which is more often found in IGCA. In DGCA specific genes such as CDH1 are more often hypermethylated. Compared with GCA, in premalignant condition lesions gene mutations and chromosomal aberrations are infrequent. Epigenetic dysregulation might also represent a major mechanism for altered gene expression in premalignant stages in gastric carcinogenesis.

Fibroblast growth factor receptor 2, gain-of-function mutations, and tumourigenesis: investigating a potential link

Activating germline mutations in the fibroblast growth factor receptor (FGFR) gene family have been identified in several dominantly inherited skeletal disorders; in the case of FGFR3, the same somatically arising mutations have also been isolated from a variety of tumour tissues. Whilst the role of FGFR2 mutations in congenital syndromes has been well documented, their relationship with cancer has not been clearly defined. Based on evidence that gain-of-function mutations in FGFR2 drive positive selection in adult spermatogonia, the present study investigated, by denaturing high-performance liquid chromatography (DHPLC), DNA sequencing, and restriction digestion, the prevalence of FGFR2 mutations in 58 tumour cell lines of various types, and 29 testicular germ cell tumour samples. Although sequence variations and allelic imbalance were identified in FGFR2, none of the previously documented dominant mutations was detected in any of the tumour types examined. This suggests that gain-of-function FGFR2 mutations are not commonly encountered in tumourigenesis and specifically excludes a major contribution in testicular tumours.

Novel regions of chromosomal amplification at 6p21, 5p13, and 12q14 in gastric cancer identified by array comparative genomic hybridization

Gastric cancer (GC) frequently displays changes in DNA copy number, but few studies have precisely correlated specific genetic alterations with changes in gene expression. We undertook both array comparative genomic hybridization (aCGH) and expression analyses of 20 primary GCs using a cDNA microarray with more than 9,300 genes. Diverse clinical and histopathologic tumor subtypes, including signet-ring tumors and tumors at the gastroesophageal junction, were analyzed. All tumors showed changes in gene copy number, with the majority showing multiple changes. Regions of gain and loss were generally consistent with previous cytogenetic reports; however, the use of aCGH greatly increased the resolution of measured genomic change. By comparing gene expression and high-resolution measurement of gene copy number directly, we were able to identify several regions of high-level gain associated with substantially increased gene expression that have not been defined previously in GC. Novel candidate oncogenes included dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 2 (DYRK2) and protein tyrosine kinase 7 (PTK7).

p150 overexpression in gastric carcinoma: the association with p53, apoptosis and cell proliferation

To clarify the significance of p150 expression, 102 gastric carcinomas were immunohistochemically investigated and 14 fresh samples of the cancer were analyzed with the immunoblot method. Tumor cell apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labeling (TUNEL). Both Ki-67 antigen and p53 expression were analyzed immunohistochemically. Eighty-six out of 102 (85%) gastric cancers stained positively for p150. All 14 tumors analyzed by Western blotting overexpressed p150. Statistical analysis revealed a close association between p150 overexpression and the clinicopathologic parameters of gastric cancer. All well-differentiated cancers showed high p150 expression (p < 0.005). Furthermore, high p150 expression was more frequently seen in tumors at early invasive stages (p < 0.005), in tumors without metastases (both local and distant, p < 0.005) and in early TNM stages (p < 0.005) in general. As we have found for cervix and esophagus carcinoma, when tumors progress to high malignancy and metastasis, p150 begins to regress and then breaks down. A good correlation of p150 expression, but not p53 expression, with tumor cell apoptosis could be demonstrated (p < 0.01). The Ki-67 labeling index, i.e., the index for a proliferative marker, showed no correlation with either p150 or p53 expression. The results suggest that p150 may be a new early tumor marker for gastric carcinoma similar to that for esophagus and cervix carcinoma.

Comparative study between DNA copy number aberrations determined by quantitative microsatellite analysis and clinical outcome in patients with stomach cancer

PURPOSE

We detected the relative DNA copy numbers (RCNs) at target loci in patients with stomach cancer with quantitative microsatellite analysis. We additionally clarified the relationship between DNA copy number aberrations and the clinical outcome of the patients.

EXPERIMENTAL DESIGN

Fresh frozen samples were obtained from 30 patients who had undergone surgery for stomach cancer. Seven microsatellite loci in chromosomes 8q, 16q, and 20q and one gene-specific locus (ZNF217) were selected as the target loci. The DNA copy number was obtained relatively to a pooled reference consisting of six microsatellite primer sets selected from the regions where few aberrations have been reported in comparative genomic hybridization analysis. On the basis of the TaqMan PCR system, the internal probes used were carrying donor (6-carboxyfluorescein) and acceptor (6-carboxytetramethylrhodamine) fluorescent molecules complementary to CA repeats in the microsatellite markers and to one gene-specific oligomer in the gene-specific marker.

RESULTS

Chromosome 8q gain, 20q gain, and 16q loss were detected in 18 (60.0%), 8 (26.7%), and 13 (43.3%) cases, respectively. Gains in the RCNs of D8S1801 and D8S1724 were most frequently found (36.7%). There was a significant correlation between the loss of D16S3026 and reduced survival duration (P = 0.0158), and the simultaneous aberrations of D8S1801 gain and D16S3026 loss (double marker positive) was significantly associated with reduced survival duration (P = 0.0008). According to Cox proportional hazards model, the double marker positive was a significant and independent factor indicating an unfavorable prognostic factor (relative risk, 17.176; 95% confidence interval, 2.782-106.026; P = 0.0022).

CONCLUSION

RCN aberrations in tumor tissues determined by quantitative microsatellite analysis enable identification of the prognostic factors that correlate with clinical outcome of the patients with stomach cancer.

Genetic alterations in 102 primary gastric cancers by comparative genomic hybridization: gain of 20q and loss of 18q are associated with tumor progression

Gastric cancer is one of the most common cancers. Molecular events in the carcinogenesis of gastric cancer remain, however, largely undefined. We investigated changes in DNA copy number in 102 gastric cancers by CGH. We found changes in DNA copy number in all cases, with frequent (> or =30% of patients) gains at 20q, 8q, 20p, 7q, 17q, 5p, and 13q. Frequent (> or =20%) losses were found at 19p, 18q, 5q, 21q, 4p, 4q, 15q, and 17p. The mean number of total alterations was significantly lower in grade 3 and scirrhous-type carcinomas (10.81 in grade 3 vs 13.98 in grade 1 and grade 2, 9.31 in scirrhous-type vs 13.18 in medullary- and intermediate-type). The mean number of losses and total alterations were higher in tumors at pT2, pT3 and pT4 (4.68 and 12.77 in pT2, pT3, and pT4 vs 2.55 and 9.22 in pT1). The mean number of losses was higher in carcinomas with lymph node metastasis (4.83). The mean number of gains and total alterations were higher in carcinomas with venous invasion (8.44 and 13.28). Several chromosomal alterations were linked in a statistically significant manner to specific clinicopathological parameters. Gain of 17q, 20p, and 20q and loss of 4p were associated with the pattern of the cancer-stroma relationship; loss of 18q was associated with pT category; gain of 5p was associated with pN category; loss of 4q and loss of 21q were associated with lymphatic invasion; gain of 7p and loss of 4q and 18q were associated with venous invasion; and loss of 18q was associated with pathological stage. These data suggest that gain of 20q and loss of 18q might play an important role in the development and progression of gastric cancer. Moreover, some genes on 20q and 18q might be target genes of gastric cancer.

Genetic lineage of poorly differentiated gastric carcinoma with a tubular component analysed by comparative genomic hybridization

Analysis of cell lineage is based on the use of genetic markers inherent to the lineage to be analysed. The breakpoints of unbalanced translocations, and the pattern of chromosomal loss/gain determined by comparative genomic hybridization (CGH), have been previously used to demonstrate lineages in diffuse-type gastric carcinoma. Signet ring cell carcinoma was shown to progress to poorly differentiated adenocarcinoma, and early diffuse-type gastric carcinoma to advanced diffuse-type gastric carcinoma. The present study focuses on poorly differentiated adenocarcinoma with a tubular component to clarify its derivation. CGH and array CGH were applied to DNA extracted from multiple portions of individual tumours and amplified by degenerate oligonucleotide-primed (DOP) PCR and the changes common to the samples in each tumour (stemline changes) were compared between the tumours with and those without a tubular component. Within individual tumours, the samples from the tubular component and those from the other components had common stemline changes and a very similar frequency pattern of chromosomal changes, indicating their common derivation. Frequent stemline changes were 8q+, 7p+, 3q+, 20q+, and 10p+, and these were different from those in the tumours without a tubular component. It was noticed that there were two subgroups in the tumours with a tubular component: one with 5p+, 6p+, 7p+, and 10p+, and the other without these changes. The latter had cytogenetic and clinicopathological features similar to those of the tumours without a tubular component. Analysis of the clonal evolution process by constructing dendrograms for each tumour gave results consistent with the notion that the latter subgroup may derive from signet ring cell carcinoma and the former from tubular adenocarcinoma.

Fibroblast growth factor receptor-3 is expressed in undifferentiated intestinal epithelial cells during murine crypt morphogenesis

Prior studies have demonstrated that fibroblast growth factor receptor-3 (FGFR-3) regulates proliferation of undifferentiated intestinal epithelial cells in vitro. However, the function(s) of FGFR-3-mediated signaling during intestinal development and epithelial differentiation in vivo remain unknown. The goal of this study was to define the temporal, regional, and cell-specific patterns of FGFR-3 expression and its ligands during normal intestinal ontogeny and epithelial regeneration. Both the IIIb and IIIc isoforms of FGFR-3 mRNA, which result from differential splicing of the FGFR-3 primary transcript, were detected in mouse small intestine as early as embryonic day 16. FGFR-3 levels peaked in the small intestine from 7 to 21 days after birth and decreased thereafter to reach the low levels observed in adult mice. FGFR-3 IIIb and IIIc mRNA levels were highest in the duodenum and proximal jejunum with lower levels of both seen in the distal jejunum, ileum, and colon. FGFR-3 was expressed in a subset of proliferating undifferentiated crypt epithelial cells located in the intervillous epithelium and in the lower half of nascently forming crypts but not in differentiated epithelial cell types. FGFR-3 IIIb was the dominant isoform expressed in both small intestinal and colonic crypts. Expression of FGF1, FGF2, and FGF9, known ligands of FGFR-3, paralleled patterns of FGFR-3 expression during gut development. These data suggest that signaling through FGFR-3 plays a role in regulating morphogenic events involved in formation of intestinal crypts and/or the fate of epithelial stem cells.

ras Gene mutations and expression of Ras signal transduction mediators in gastric adenocarcinomas

OBJECTIVE

To investigate ras gene alteration in human gastric adenocarcinomas and its potential relationship to ras signal transduction mediators.

DESIGN

Genomic DNA from 104 gastric tumors were analyzed by sequencing of polymerase chain reaction-amplified products for the presence of ras mutations. All the samples were further investigated with the use of immunohistochemical analysis for ERK1 and ERK2.

SETTING

Tertiary care teaching hospital.

PATIENTS

Seventy patients from a Korean population and 34 from a Midwestern US population composed of white Americans and African Americans.

RESULTS

Fifteen tumors (14%) were positive for either H-ras or K-ras mutation: 9 (13%) of 70 Korean patients and 6 (18%) of 34 US patients. Seven (78%) of the 9 mutated tumors from Korean patients and all 6 (100%) from the US patients were intestinal-type lesions. Either ERK1 and/or ERK2 was overexpressed in 68 samples (65%). No association was established between ras mutations and overexpression of ERK1/2. However, the correlation between ERK1/2 and progression (early vs late) was statistically significant (P =.007).

CONCLUSIONS

These data suggest that ras mutations are uncommon in gastric adenocarcinomas and that differing racial and/or geographic mechanisms may not underlie ras gene alteration. Most ras mutations were, however, observed in the group of intestinal-type samples, supporting the different genetic mechanisms of carcinogenesis between the intestinal- and diffuse-type tumors. It is noteworthy that enhanced ERK1/2 activity could be one of the characteristics of tumor invasiveness in gastric cancers.

A novel splice variant of fibroblast growth factor receptor 2 in human leukemia HL-60 cells

Fibroblast growth factor receptors (FGFRs) genes have been shown to be translocated in multiple myeloma (MM) and myeloproliferative disorder (MPD), indicating an important role for the FGFRs in hematologic malignancies. Here, we describe a novel splice variant of FGFR2 (FGFR2AT-I) arising from skipping exons 7-10 in human myeloid leukemia HL-60 cells, encoding a FGFR2 in which the Ig-like-III domain is deleted while the remainder of the mature molecule is fused in-frame to the transmembrane and COOH-terminal cytoplasmic kinases. Binding assays demonstrated that the FGFR2AT-I was able to bind FGF1, FGF2, and FGF7, leading to loss of ligand binding specificity. Furthermore, overexpression of FGFR2AT-I resulted in increased AKT and MAPK activation, conferring a survival advantage. Taken together, these findings indicate that the dysregulation of FGFRs' function by aberrant mRNA splicing contributes to tumor progression.

Keratinocyte growth factor regulates proliferation and differentiation of hematopoietic cells expressing the receptor gene K-sam

OBJECTIVE

The aim of this study was to establish a new method to overcome the problems of gene therapy targeting hematopoietic cells, namely low transduction efficiency and induction of differentiation during cytokine treatment.

MATERIALS AND METHODS

The K-sam gene encoding the receptor for keratinocyte growth factor (KGF) was transduced to three factor-dependent hematopoietic cell lines (Ba/F3, 32Dcl3, and UT-7/GM) using retroviral vector, and their proliferation, differentiation, and intracellular signaling were studied. This gene also was transduced to murine bone marrow cells, and proliferation of colony-forming cells (CFCs) by KGF stimulation was examined.

RESULTS

Although KGF is known to target only epithelial cells, all of the three cell lines transduced with K-sam proliferated due to KGF stimulation. Morphologic observation showed that KGF induced proliferation but did not cause significant differentiation of 32D/K-sam cells. KGF treatment increased phosphorylation of ERK1/2 but did not activate STAT molecules. Granulocyte colony-stimulating factor transduced the differentiation signal with the phosphorylation of STAT3 without significant ERK1/2 activation. Proliferation by KGF of murine primary bone marrow cells transduced with K-sam then was examined in liquid culture. KGF treatment significantly increased production of CFCs derived from K-sam-transduced bone marrow cells without causing the exhaustion of immature CFCs.

CONCLUSIONS

KGF could efficiently induce proliferation of hematopoietic cells expressing the K-sam gene without obvious induction of differentiation or exhaustion of immature progenitor cells. The in vitro data are important for further preclinical in vivo study.

Expression of the insulin-like growth factors (IGFs) and the IGF-binding proteins (IGFBPs) in human gastric cancer cells

Insulin-like growth factor (IGF)-I and -II are potent mitogens and postulated to exert autocrine, and paracrine effects on growth regulation in human gastric cancer. Their mitogenic effects are tightly regulated by the IGF binding proteins (IGFBPs). In this study, we evaluated the mRNA expression of IGF-I, IGF-II and the IGFBPs in a panel of human gastric cancer cell lines, and normal and tumour tissue specimens from patients with gastric cancer by reverse transcriptase-polymerase chain reaction (RT-PCR) and competitive PCR. Conditioned media (CM) of the gastric cancer cell lines were studied for the secretion of the IGFBPs by western ligand blot (WLB) and western immunoblot (WIB). IGF-I and IGF-II were expressed in all of the gastric cancer cell lines, and the normal and tumour tissue specimens. Overexpression of the IGFs, in particular, IGF-II, was observed in the tumour tissues. The expression pattern of IGFBPs was heterogeneous among the gastric cancer cell lines. IGFBP-2 was expressed in all of the gastric cancer cell lines, whereas IGFBP-1 was not detected in any cell lines. IGFBP-4 was expressed in the most of cell lines. IGFBP-3, IGFBP-5 and IGFBP-6 were expressed in approximately 50% of cell lines. In addition, exogenous IGF-I and IGF-II stimulated the proliferation of gastric cancer cells, suggesting the existence of a functional IGF system in gastric cancer. Taken together, our data-suggest that the IGF-IGFBP system may play an important role in the initiation, progression and metastasis of gastric cancer. Further studies are needed to understand the exact role of IGFs and IGFBPs in gastric neoplasia.

Chromosomal alterations in paired gastric adenomas and carcinomas

Gastric adenoma is a precancerous lesion of the stomach and its malignant transformation is thought to result from accumulative series of gene alterations. The aim of this study was to determine the pattern of chromosomal changes during gastric carcinogenesis. Pairs of adenoma and carcinoma tissues from 15 gastrectomy cases containing both adenomas and carcinomas in the same (adjacent pairs, 6 cases) and different (non-adjacent pairs, 9 cases) lesions, were analyzed for chromosomal alterations of 39 non-acrocentric chromosomal arms by comparative genomic hybridization (CGH). CGH analysis identified frequent chromosomal alterations in most of the gastric adenomas (14/15, 93%) and all of the carcinomas. The mean number of chromosomal alterations was higher in carcinoma (5.5 for adenoma and 11.7 for carcinoma; P = 0.006, by nonparametric Wilcoxon's test). Losses on the short arm of chromosome 17 were most common in both adenomas (43%) and carcinomas (67%). The pattern of chromosomal alterations in paired gastric adenomas and carcinomas showed greater similarity compared to the non-case pairs and this similarity was increased in the adjacent pairs. Deletion mapping analysis on chromosome 17p also demonstrated that the conserved deletion area was more frequent in the adjacent pairs. Among these 6 adjacent pairs, all had common deletion areas. In contrast, among the 9 non-adjacent pairs, 2 (22%) had common area of deletion, 5 (56%) showed deletion only in the carcinoma, and the remaining 2 (22%) had no deletion on 17p, suggesting diverse genetic changes might be involved in the multiple tumor formation. Our results that common clonal genetic changes between adjacent pairs of gastric adenomas and carcinomas and accumulated genetic changes in the carcinomas provide evidences for the stepwise mode of gastric carcinogenesis through the accumulation of a series of genetic alterations.

Activated fibroblast growth factor receptor 3 is an oncogene that contributes to tumor progression in multiple myeloma

The t(4;14) translocation occurs frequently in multiple myeloma (MM) and results in the simultaneous dysregulated expression of 2 potential oncogenes, FGFR3 (fibroblast growth factor receptor 3) from der(14) and multiple myeloma SET domain protein/Wolf-Hirschhorn syndrome candidate gene 1 from der(4). It is now shown that myeloma cells carrying a t(4;14) translocation express a functional FGFR3 that in some cases is constitutively activated by the same mutations that cause thanatophoric dysplasia. As with activating mutations of K-ras and N-ras, which are reported in approximately 40% of patients with MM, activating mutations of FGFR3 occur during tumor progression. However, the constitutive activation of ras and FGFR3 does not occur in the same myeloma cells. Thus the activated forms of these proteins appear to share an overlapping role in tumor progression, suggesting that they also share the signaling cascade. Consistent with this prediction, it is shown that activated FGFR3-when expressed at levels similar to those seen in t(4;14) myeloma-is an oncogene that acts through the MAP kinase pathway to transform NIH 3T3 cells, which can then generate tumors in nude mice. Thus, FGFR3, when overexpressed in MM, may be not only oncogenic when stimulated by FGF ligands in the bone marrow microenvironment, but is also a target for activating mutations that enable FGFR3 to play a ras-like role in tumor progression.

Tyrosine kinases and gastric cancer

Carcinoma of the stomach is one of the most prevalent cancer types in the world today. Two major forms of gastric cancer are distinguished according to their morphological and clinicopathological classifications (well differentiated/intestinal type and poorly differentiated/diffuse type), characteristics that could also be attributed to the altered expression of different types of oncogenes or tumor suppressor genes. Significant differences exist for gastric cancer incidence comparing people of different ethnic origins, implicating various genetic and epigenetic factors for gastric oncogenesis. There are only a limited number of molecular markers available for gastric cancer detection and prognostic evaluation, among which are tyrosine kinases. There is convincing evidence that tyrosine kinases are involved in oncogenesis and disease progression for many human cancers. Amplifications of certain tyrosine kinases (c-met, k-sam and erbB2/neu) have been associated with human gastric cancer progression. Alternatively spliced transcripts and enhanced protein-expression levels for some of these tyrosine kinases are correlated with clinical outcomes for gastric cancer patients. With advent of high throughput techniques, it is now possible to detect nearly all expressed tyrosine kinases in a single screen. This increases the chance to identify additional tyrosine kinases as predictive markers for gastric cancers. In this article, we will first review the literature data concerning certain tyrosine kinases implicated in gastric carcinogenesis and then summarize more recent work which provide comprehensive tyrosine kinase profiles for gastric cancer specimens and cell lines. Two new gastric cancer molecular markers (tie-1 and mkk4) have been identified through the use of these profiles and demonstrated effective as clinical prognostic indicators.

Recurrent chromosome changes in 62 primary gastric carcinomas detected by comparative genomic hybridization

Comparative genomic hybridization (CGH) has been applied to detect recurrent chromosome alterations in 62 primary gastric carcinomas. Several nonrandom chromosomal changes, including gains of 8q (31 cases, 50%), 20q (29 cases, 47%) with a minimum gain region at 20q11. 2-q12, 13q (21 cases, 34%) with a minimum gain region at 13q22, and 3q (19 cases, 31%) were commonly observed. The regions most frequently lost included: 19p (23 cases, 37%), 17p (21 cases, 33%), and 1p (14 cases, 23%). High copy number gain (DNA sequence amplification) was detected in 6 cases. Amplification of 8q23-q24.2 and 20q11.2-q12 were observed in 3 cases. Gain of 20q and loss of 19p were confirmed by fluorescence in situ hybridization using corresponding bacterial artificial chromosomes (BAC) clones from those regions. The gain and loss of chromosomal regions identified in this study provide candidate regions involved in gastric tumorigenesis.

Functional characterization of the keratinocyte growth factor system in human fetal gastrointestinal tract

Keratinocyte growth factor (KGF) is a paracrine growth factor whose mRNA has been detected in human adult and rodent gut tissues together with its associated receptor. Our objectives were to assess the presence of immunoreactive KGF ligand and receptor proteins in human fetal gastrointestinal (GI) tract segments and to evaluate the role of exogenous KGF on cell proliferation and intestinal digestive functions. KGF (26-28 kD doublet) was identified in esophagus, stomach, small intestine, and colon by Western blot. Its receptor (135 kD) was ubiquitously detected in proliferative and differentiated epithelial cells of each GI segment by use of indirect immunofluorescence (anti-bek, anti-K-sam). The addition of KGF to explants cultured in serum-free conditions greatly stimulated DNA synthesis in all GI tract tissues. The growth factor up-regulated intestinal sucrase-isomaltase and gamma-glutamyl-transpeptidase activities in jejunal explants, whereas it down-regulated these activities in colon explants. It is suggested that the KGF system likely represents an important paracrine pathway that is able to stimulate cell proliferation in all segments of the human fetal GI tract and to differentially regulate intestinal digestive functions.

Molecular characteristics of eight gastric cancer cell lines established in Japan

Molecular characterization of eight gastric cancer cell lines established in Japan are summarized according to the genetic and epigenetic alterations and growth factor status. TMK-1 poorly differentiated adenocarcinoma cell line harbors mutant p53 tumor suppressor gene and rearrangement of p15MTS2. MKN-1 adenosquamous carcinoma line with mutant p53 reveals silencing of E-cadherin by promoter CpG hypermethylation. MKN-7 well-differentiated adenocarcinoma cell line has amplification of c-erbB2 oncogene and cyclin E gene. MKN-28 well-differentiated adenocarcinoma cell line reveals mutations in p53 and APC tumor suppressor genes and silencing of CD44. The MKN-45 poorly differentiated adenocarcinoma cell line with wild-type p53 is characterized by homozygous deletion of p16CDKN2/MTS1/INK4A and p15MTS2, amplification of c-met oncogene and promoter mutation of E-cadherin. MKN-74 derived from moderately differentiated tubular adenocarcinoma has wild-type p53. KATO-III signet ring cell carcinoma line has genomic deletion of p53, amplification of K-sam and c-met oncogene and mutation of E-cadherin. HSC-39 signet ring cell carcinoma cell line harboring p53 missense mutation has homozygous deletion of p16CDKN2/MTS1/INK4A and p15MTS2, amplifications of c-myc, c-met, K-sam and CD44 gene and mutation in beta-catenin gene.

Fibroblast growth factor-10: a stromal mediator of epithelial function in the ovine uterus

Fibroblast growth factor-10 (FGF-10) is a stromal-derived paracrine growth factor considered to be important during embryogenesis; however, its expression by cells in the female reproductive tract has not been investigated. Therefore, an ovine FGF-10 cDNA was cloned from an ovine endometrial cDNA library to investigate expression and potential paracrine characteristics of FGF-10 in the ovine uterus. The ovine FGF-10 cDNA encodes a protein of 213 amino acids and possesses an unusually long 5' untranslated region (UTR). In situ hybridization demonstrated that ovine FGF-10 mRNA was expressed by endometrial stromal cells and by mesenchymal cells of the chorioallantoic placenta. The mRNA for FGF-7, a homologue of FGF-10, was localized in the tunica muscularis of blood vessels in endometrium and myometrium. In contrast, FGF receptor 2IIIb, the high-affinity receptor for both FGF-10 and FGF-7, was expressed exclusively in luminal epithelium, glandular epithelium, and placental trophectoderm. The in vivo spatial expression pattern suggests that FGF-10 is a novel endometrial stromal cell-derived mediator of uterine epithelial and conceptus trophectodermal functions. The nonoverlapping spatial patterns of expression for FGF-10 and FGF-7 in ovine uterus and conceptus suggest independent roles in uterine function and conceptus development.

Allelic loss of the region of chromosome 1p35-pter is associated with progression of human gastric carcinoma

In order to identify the region on distal chromosome 1p that is thought to include one or more tumor suppressor genes for gastric carcinoma, 39 gastric carcinomas were examined for allelic loss using 11 polymorphic microsatellite markers and 1 marker of single strand conformation polymorphism. Loss of heterozygosity (LOH) was found in 18 (46%) of 39 informative patients. The regions with high frequency of loss of heterozygosity were the loci at D1S548 (6 / 17; 35.3%) and D1S2843 (7 / 20; 35%), and we found three commonly deleted regions on chromosome 1p35-pter. The frequency of allelic loss in the region of chromosome 1p35-pter was significantly associated with advanced-stage gastric carcinoma, but not with early-stage tumor or with the histology. These results suggest that allelic loss at chromosome 1p35-pter may play a role in the progression of gastric carcinoma.

Keratinocyte growth factor: expression by endometrial epithelia of the porcine uterus

Keratinocyte growth factor/fibroblast growth factor-7 (KGF/FGF-7) is an established paracrine mediator of hormone-regulated epithelial growth and differentiation. In all organs studied, KGF is uniquely expressed in cells of mesenchymal origin. To determine whether KGF and its receptor, keratinocyte growth factor receptor (KGFR) or fibroblast growth factor receptor-2IIIb, were expressed in the porcine uterus as a potential paracrine system mediating progesterone action, we cloned KGF and KGFR partial cDNAs from the porcine endometrium. KGF and KGFR expression was detected in endometrium by Northern blot hybridization. Interestingly, in situ hybridization results demonstrated that KGF was expressed by endometrial epithelia and was particularly abundant between Days 12 and 15 of the estrous cycle and pregnancy. KGF secretion into the lumen of the porcine uterus was also detected on Day 12 of the estrous cycle and pregnancy. KGFR was expressed in both endometrial epithelia and conceptus trophectoderm. These novel findings suggest that KGF may act on the uterine endometrial epithelium in an autocrine manner and on the conceptus trophectoderm in a paracrine manner in the pig, which is the only species possessing a true epitheliochorial type of placentation.

Sequential numerical changes of chromosomes 7 and 18 in diffuse-type stomach cancer cell lines: combined comparative genomic hybridization, fluorescence in situ hybridization, and ploidy analyses

Sequential changes of chromosomal copy number were analyzed retrospectively in five diffuse-type gastric cancer cell lines by comparative genomic hybridization (CGH), DNA cytometry, and fluorescence in situ hybridization (FISH) with centromeric and painting probes. By CGH, we found loss of 18q21 in all of the cell lines and gains of 7p11-q31, 20q, and 22 in four of the five cell lines. Actual copy numbers of chromosomes 7 and 18 were determined by FISH: disomy 18 with (partial) loss of 18q in the two DNA-diploid cell lines (AGS and MKN-45), trisomy 7 in MKN-45, disomy 18 and tetrasomy 7 with one-copy loss of 7p and one-copy gain of 7q tip in DNA-triploid HSC-39/40A, and trisomy 18 and hexasomy 7 with one-copy loss of 7q in DNA-tetraploid KATO-III. Because the DNA aneuploidy is thought to result through tetraploidization, and the duplicated chromosomal changes in DNA aneuploid tumors seem to precede tetraploidization, the duplicated gain of chromosome 7 and one-copy loss of 7q in KATO-III were inferred to have occurred before and after tetraploidization, respectively. Similarly, HSC-39/40A were inferred to be preceded by the DNA-diploid stage with disomy 7 and monosomy 18. As the loss of 18q21 and the gain of 7p11-q31 were inferred to have occurred already in the DNA diploid stage in at least four and two of the cell lines, respectively, the 18q21 loss may be more important than the 7q gain as an earlier event in the genesis of diffuse-type stomach cancer. The combined CGH, FISH, and ploidy analyses thus give us a clue to extract important earlier events from the chromosomal changes that were screened by CGH alone.

Role of fibroblast growth factor-2 in human brain: a focus on development

Trophic factors have gained a great degree of attention as regulators of neural cells proliferation and differentiation as well as of brain maturation. Very little is known, however, about their effects on human immature nervous system. In this paper, data on expression of fibroblast-growth factor-2 and its receptors are reviewed and discussed in the light of its possible role in human brain development.

Expression of keratinocyte growth factor and its receptor in colorectal cancer

BACKGROUND AND AIMS

The mesenchymal derived keratinocyte growth factor stimulates growth, differentiation and migration of intestinal epithelial cells. In the human gastrointestinal tract an overexpression of this growth factor has been reported in inflammatory bowel disease and pancreatic cancer. In the present study we investigated expression patterns of keratinocyte growth factor and receptor in normal and neoplastic colonic mucosa and in metastases. Furthermore, biological effects on normal intestinal and colorectal cancer cell lines were determined.

MATERIALS AND METHODS

Expression patterns were analysed at the mRNA level by reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. Localization of ligand and receptor in normal intestinal mucosa and cancer tissue was investigated by immunohistochemistry. Mitogenic effects of keratinocyte growth factor were assayed by [3H]thymidine incorporation in normal (Intestine-407, IEC-6, IEC-18) and colorectal cancer cell lines (Colo320, LoVo, SW403, SW707).

RESULTS

mRNA expression of keratinocyte growth factor and receptor was detected in the majority of normal and cancer samples without significant alterations. At the protein level keratinocyte growth factor expression did not differ between normal and malignant specimens, whereas protein expression of the receptor was increased up to twofold in well- to moderately differentiated colorectal cancers. DNA synthesis was significantly stimulated by keratinocyte growth factor in all three normal intestinal cell lines, whereas this growth factor did not significantly alter the [3H]thymidine incorporation in the colorectal cancer cell lines.

CONCLUSION

Keratinocyte growth factor and its receptor were detected in the majority of samples from normal and neoplastic colonic mucosa, with an overexpression of the receptor seen in the more differentiated tumour samples. Keratinocyte growth factor is a strong mitogen for normal intestinal cells, whereas it is less effective in neoplastic cells.

Normal human fibroblasts produce membrane-bound and soluble isoforms of FGFR-1

Fibroblast growth factors (FGFs) are polypeptide mitogens for a wide variety of cell types and are involved in other processes such as angiogenesis and cell differentiation. FGFs mediate their biological responses by activating high-affinity tyrosine kinase receptors. Currently, there are four human fibroblast growth factor receptor (FGFR) genes. To investigate the mechanisms by which alpha FGF and beta FGF may mediate mitogenic signal transduction in human skin-derived fibroblasts, we analyzed these cells for the presence of high-affinity FGFRs. We show that normal human dermal fibroblasts express a single high-affinity FGFR gene, FGFR-1. Cloning and sequencing of two distinct FGFR-1 cDNAs suggested that normal human dermal fibroblasts express a membrane-bound and a putatively secreted form of FGFR-1. We show that normal human dermal fibroblasts produce two FGFR-1 proteins, one of which exists in conditioned media. The mRNA for the putatively secreted form of FGFR-1 appears to be down-regulated by serum treatment of the cells.

Tumour suppressive properties of fibroblast growth factor receptor 2-IIIb in human bladder cancer

FGFRs (fibroblast growth factor receptors) are encoded by four genes (FGFR1-4). Alternative splicing results in various receptor isoforms. The FGFR2-IIIb variant is present in a wide variety of epithelia, including the bladder epithelium. Recently, we have shown that FGFR2-IIIb is downregulated in a subset of transitional cell carcinomas of the bladder, and that this downregulation is associated with a poor prognosis. We investigated possible tumour suppressive properties of FGFR2-IIIb by transfecting two human bladder tumour cell lines, J82 and T24, which have no endogenous FGFR2-IIIb expression, with FGFR2-IIIb cDNA. No stable clones expressing FGFR2-IIIb were isolated with the J82 cell line. For the T24 cell line, stable transfectants expressing FGFR2-IIIb had reduced growth in vitro and formed fewer tumours in nude mice which, in addition, grew more slowly. The potential mechanisms leading to decreased FGFR2-IIIb mRNA levels were also investigated. The 5' region of the human FGFR2 gene was isolated and found to contain a CpG island which was partially methylated in more than half the cell lines and tumours which do not express FGFR2-IIIb. No homozygous deletion was identified in any of the tumours or cell lines with reduced levels of FGFR2-IIIb. Mutational analysis of the entire coding region of FGFR2-IIIb at the transcript level was performed in 33 bladder tumours. In addition to normal FGFR2-IIIb mRNA, abnormal transcripts were detected in two tumour samples. These abnormal mRNAs resulted from exon skipping which affected the region encoding the kinase domain. Altogether, these results show that FGFR2-IIIb has tumour growth suppressive properties in bladder carcinomas and suggest possible mechanisms of FGFR2 gene inactivation.

Novel exons located more than 200 kb downstream of the previously described 3' exon of the K-sam gene for generating activated forms of KGF receptor

The K-sam gene was first identified as an amplified gene in the poorly differentiated types, especially in the scirrhous type, of gastric cancers. We have recently found and reported that the carboxyl-terminal exons of K-sam are frequently deleted in the scirrhous type of gastric cancer. The deletion generates preferential expression of at least six novel K-sam-II mRNAs: K-sam-IIH1, -IIH2 and -IIH3/O4, and K-sam-IIO1, -IIO2, and -IIO3, which encode novel proteins lacking the transformation-inhibitory sequence or activated K-sam proteins. In this study, we investigated expression of the previously described K-sam-IIC1 and -IIC3 mRNAs and the novel six K-sam-II mRNAs in 14 gastric cancer cell lines, 7 breast cancer cell lines, and 20 human normal tissues. All the six novel K-sam-II mRNAs were expressed preferentially in the cell lines derived from the scirrhous type of gastric cancers but not in the 7 breast cancer cell lines and the 20 human normal tissues. We further determined the positional relationship of four exons of H1, O1, O2, and O3 out of the six exons of H1, H2, H3/O4, O1, O2, and O3, and found that these four novel K-sam exons were located more than 200 kb downstream of the previously described carboxyl-terminal exon of the K-sam gene. Expression of K-sam-IIH1, -IIO1, and -IIO2 mRNAs encoding activated K-sam products in the scirrhous type of gastric cancer cell lines HSC39, OCUM2M, HSC59, and HSC60 was not due to the deletion of the C1 exon of K-sam.

The acidic domain and first immunoglobulin-like loop of fibroblast growth factor receptor 2 modulate downstream signaling through glycosaminoglycan modification

Fibroblast growth factor receptors (FGFRs) are membrane-spanning tyrosine kinases that have been implicated in a variety of biological processes including mitogenesis, cell migration, development, and differentiation. We identified a unique isoform of FGFR2 expressed as a diffuse band with an unusually large molecular mass. This receptor is modified by glycosaminoglycan at a Ser residue located immediately N terminal to the acidic box, a stretch of acidic amino acids. The acidic box and the glycosaminoglycan modification site are encoded by an alternative exon of the FGFR2 gene. The acidic box appears to play an important role in glycosaminoglycan modification, and the presence of this domain is required for modification by heparan sulfate glycosaminoglycan. Moreover, the presence of the first immunoglobulin-like domain encoded by another alternative exon abrogated the modification. The high-affinity receptor with heparan sulfate modification enhanced receptor autophosphorylation, substrate phosphorylation, and ternary complex factor-independent gene expression. It also sustained mitogen-activated protein kinase activity and increased eventual DNA synthesis, a long-term response to fibroblast growth factor stimulation, at physiological ligand concentrations. We propose a novel regulation mechanism of FGFR2 signal transduction through glycosaminoglycan modification.

Identification of a novel activated form of the keratinocyte growth factor receptor by expression cloning from parathyroid adenoma tissue

Parathyroid adenomas are benign tumors in the parathyroid glands, whose pathogenesis is largely unknown. We utilized an expression cDNA cloning strategy to identify oncogenes activated in parathyroid adenomas. An expression cDNA library was prepared directly from a clinical sample of parathyroid adenoma tissue, transfected into NIH3T3 cells, and foci of morphologically transformed cells were isolated. Following plasmid rescue, we identified cDNAs for the keratinocyte growth factor receptor at a high frequency. Interestingly, approximately half of the clones encoded a variant receptor containing an altered C-terminus. Analysis of the transforming activity of the variant receptor revealed that the altered C-terminus up-regulated the transforming activity in a ligand-independent manner. The higher transforming activity was not accompanied by increase of dimerization or overall autophosphorylation of the receptor. However, tyrosine phosphorylation of downstream receptor substrates, including Shc isoforms and possibly FRS2, are increased in the transfectants expressing the parathyroid tumor-derived receptor. Genomic analysis showed that a previously unidentified exon was used to form the novel isoform. This alternative splicing appears to occur preferentially in parathyroid adenomas.

The prognostic significance of amplification and overexpression of c-met and c-erb B-2 in human gastric carcinomas

BACKGROUND

The c-met and the c-erb B-2 protooncogenes belong to a family of tyrosine kinase growth factor receptors. Abnormalities of these oncogenes and protein products have been reported in several cancers. The authors investigated the correlation between clinical factors and amplification or overexpression of the c-met and/or c-erb B-2 gene in Japanese patients with gastric carcinoma patients, with a focus on prognostic significance.

METHODS

Amplification and overexpression of c-met and c-erb B-2 were investigated retrospectively in 128 gastric carcinoma patients by using immunohistochemistry and Southern blot hybridization. Survival analysis was performed with the Kaplan-Meier test, and the log rank test was used for statistical analysis.

RESULTS

Overexpression of c-met and c-erb B-2 was observed in 46.1% and 16.4% of gastric carcinoma cases, respectively. Gene amplification of c-met and c-erb B-2 was detected in 10.2% and 11.7% of gastric carcinoma cases, respectively. Amplification and overexpression of c-met were correlated significantly with depth of tumor invasion and lymph node metastasis, whereas amplification and overexpression of c-erb B-2 were correlated significantly with histologic type. The survival rate of patients with amplification and/or overexpression of c-met or c-erb B-2 was significantly poorer than that of patients with no amplification or overexpression. Multivariate analysis revealed that c-met overexpression and lymph node metastasis were independent prognostic factors.

CONCLUSIONS

These data suggest that overexpression and/or gene amplification of c-met and c-erb B-2 may be prognostic factors in gastric carcinoma.

Chromosome band 16q24 is frequently deleted in human gastric cancer

We have analysed the loss of heterozygosity (LOH) on chromosome bands 16q22-q24 in 24 primary gastric cancer tissues and found three regions of frequent allelic loss (16q22, 16q24.1-q24.3 and 16q24.3). The region for the most frequent allelic loss (63%) was in 16q24.1-q24.3. LOH of this region had no relationship with histological subtype, but a significant association between LOH and microscopic lymphangial invasion was observed. Although not significant, vascular and gastric wall invasions are also associated with LOH. The region includes the locus for the H-cadherin gene. Therefore we examined the genetic and epigenetic alterations of this gene. Markedly reduced expression was observed in gastric cancer cell lines compared with that of normal gastric mucosa. However, no mutation was found in this gene in any of the gastric cancer tissues or the gastric cancer cell lines. Furthermore, we analysed the methylation status of the 5'-flanking region of the gene, but no significant association was found. We suggest that some other tumour suppressor gene(s) in 16q24.1-q24.3 may be responsible for gastric carcinogenesis.

Expression of cell-cycle regulators, cyclin E and p21WAF1/CIP1, potential prognostic markers for gastric cancer

AIMS

The deregulation of cyclin, cyclin-dependent kinases (CDKs) and their inhibitors could have a crucial role in the development of diverse human cancers.

METHODS

In this study, we analysed the expression of cyclin D1, cyclin E, p21WAF1/CIP1 and p27KIP1 in 84 surgically resected gastric cancers by immunohistochemistry with long-term follow-up (median 38 months). We also evaluated the relation between each cell cycle regulator and various clinicopathological findings, including age, sex, histological grade, tumour location, tumour type and stage and lymph-node metastasis.

RESULTS

Overexpression of cyclin D1 and E was detected in 21/84 (25%) and 34/84 (40.5%) patients, respectively. Normal gastric epithelium showed consistently positive immunostain for p21WAF1/CIP1 and p27KIP1 in more than 50% of nuclei. Loss of p21WAF1/CIP1 and p27KIP1 expression was noted in 45/84 (53.6%) and 44/84 (52.4%) patients, respectively. Among the various clinicopathological findings, overexpression of cyclin E was associated with lymph-node metastasis (P=0.003) and recurrence (P=0.043). Loss of p21WAF1/CIP1 expression was more frequent in diffuse type cancers (P=0.005) and was correlated with recurrence (P=0.002) and death (P=0.002). Overexpression of cyclin E and loss of p21WAF1/CIP1 expression were significantly correlated with decreased disease-free (P=0.037; P= 0.001) and overall (P=0.031; P=0.001) survival.

CONCLUSIONS

These results suggest that immunohistochemical analysis for cell cycle regulators, especially cyclin E and p21WAF1/CIP1, might be a useful prognostic indicator in gastric cancer.

FGF-18, a novel member of the fibroblast growth factor family, stimulates hepatic and intestinal proliferation

The fibroblast growth factors (FGFs) play key roles in controlling tissue growth, morphogenesis, and repair in animals. We have cloned a novel member of the FGF family, designated FGF-18, that is expressed primarily in the lungs and kidneys and at lower levels in the heart, testes, spleen, skeletal muscle, and brain. Sequence comparison indicates that FGF-18 is highly conserved between humans and mice and is most homologous to FGF-8 among the FGF family members. FGF-18 has a typical signal sequence and was glycosylated and secreted when it was transfected into 293-EBNA cells. Recombinant murine FGF-18 protein (rMuFGF-18) stimulated proliferation in the fibroblast cell line NIH 3T3 in vitro in a heparan sulfate-dependent manner. To examine its biological activity in vivo, rMuFGF-18 was injected into normal mice and ectopically overexpressed in transgenic mice by using a liver-specific promoter. Injection of rMuFGF-18 induced proliferation in a wide variety of tissues, including tissues of both epithelial and mesenchymal origin. The two tissues which appeared to be the primary targets of FGF-18 were the liver and small intestine, both of which exhibited histologic evidence of proliferation and showed significant gains in organ weight following 7 (sometimes 3) days of FGF-18 treatment. Transgenic mice that overexpressed FGF-18 in the liver also exhibited an increase in liver weight and hepatocellular proliferation. These results suggest that FGF-18 is a pleiotropic growth factor that stimulates proliferation in a number of tissues, most notably the liver and small intestine.

Fibroblast growth factor receptor-1 expression in the cortex and hippocampus in Alzheimer's disease

Localization of fibroblast growth receptor (FGFR)-1 immunoreactivity was investigated immunochemically in postmortem brain tissue of Alzheimer's disease (AD) and age-matched control cases using a rabbit polyclonal antibody and a mouse monoclonal antibody specific for FGFR-1. In control cases, FGFR-1 immunoreactivity was identified in astrocytes in white matter and in hippocampal pyramidal neurons. In AD cases, the immunoreactivity in reactive astrocytes surrounding senile plaques was increased. The pattern of FGFR-1 immunoreactivity was confirmed in selected cases by in situ hybridization for FGFR-1 mRNA. Immunoreactivity using a monoclonal antibody demonstrated a similar distribution pattern. The localization of FGFR-1 is consistent with previous reports on the involvement of FGF-1 and FGF-2 in AD.

An intronic sequence element mediates both activation and repression of rat fibroblast growth factor receptor 2 pre-mRNA splicing

Alternative splicing of fibroblast growth factor receptor 2 (FGF-R2) is an example of highly regulated alternative splicing in which exons IIIb and IIIc are utilized in a mutually exclusive manner in different cell types. The importance of this splicing choice is highlighted by studies which indicate that deregulation of the FGF-R2 splicing is associated with progression of prostate cancer. Loss of expression of a IIIb exon-containing isoform of FGF-R2 [FGF-R2 (IIIb)] accompanies the transition of a well-differentiated, androgen-dependent rat prostate cancer cell line, DT3, to the more aggressive, androgen-independent AT3 cell line. We have used transfection of rat FGF-R2 minigenes into DT3 and AT3 cancer cell lines to study the mechanisms that control alternative splicing of rat FGF-R2. Our results support a model in which an important cis-acting element located in the intron between these alternative exons mediates activation of splicing using the upstream IIIb exon and repression of the downstream IIIc exon in DT3 cells. This element consists of 57 nucleotides (nt) beginning 917 nt downstream of the IIIb exon. Analysis of mutants further demonstrates that an 18-nt "core sequence" within this element is most crucial for its function. Based on our observations, we have termed this sequence element ISAR (for intronic splicing activator and repressor), and we suggest that factors which bind this sequence are required for maintenance of expression of the FGF-R2 (IIIb) isoform.

The heparan sulfate-fibroblast growth factor family: diversity of structure and function

The fibroblast growth factor (FGF) receptor complex is a ubiquitous regulator of development and adult tissue homeostasis that bridges the peri-cellular matrix and the intracellular environment. Diverse members of the FGF polypeptide family, the FGF receptor tyrosine kinase (FGFRTK) family and the FGF receptor heparan sulfate proteoglycan (FGFRHS) family combine to result in active and specific FGFR signal transduction complexes. Regulated alternate splicing and combination of variant subdomains give rise to diversity of FGFRTK monomers. Divalent cations cooperate with the FGFRHS to conformationally restrict FGFRTK trans-phosphorylation, which causes depression of kinase activity and facilitates appropriate activation of the FGFR complex by FGF. Diffusional and conformational molecular models of the oligomeric FGFR complex are presented to explain how different point mutations in the FGFRTK commonly cause craniofacial and skeletal abnormalities of graded severity by graded increases in FGF-independent activity of total FGFR complexes. The role of the FGF family in liver growth and function and in prostate tumor progression is discussed.

Effect of fibroblast growth factor saporin mitotoxins on human bladder cell lines

Mitotoxins targeted via high-affinity growth factor receptors on the cell surface are a potential means of anticancer therapy. We have evaluated the effect of a chemically conjugated (FGF2-SAP) and a fusion protein (rFGF2-SAP) mitotoxin containing FGF-2 and saporin on normal (FHs 738B1) and malignant bladder cell lines (HT1197, TCCSUP, EJ-6, and RT4). The FGF-saporins demonstrated potent cytotoxicity in malignant bladder cell lines with an ID50 range of 0.13-13.6 nM, whereas cells derived from normal fetal bladder (FHs 738B1) were less sensitive to FGF2-saporins (ID50 > 100 nM). Greater than a 100-fold difference in cytotoxicity between FGF-saporins and unconjugated saporin was observed. Assessment of cellular FGF-2 content and secretion showed that FHs 738B1 and TCCSUP contained and secreted significantly more FGF-2 compared to other cell lines tested. (125)I-FGF-2 receptor binding studies showed the presence of high-affinity (pM) FGF receptors on all bladder cell lines. Cross-linking studies revealed the presence of a major receptor-ligand complex of 90 kDa on FHs 738B1 and 160-170 kDa on the other bladder cell lines. All cell lines studied, except RT4, expressed solely FGFR-1. These studies demonstrate that FGF2-saporins have antiproliferative activity on human bladder cancer cell lines. However, the number of high-affinity FGF receptors, and FGF-2 cellular content and secretion are not absolute determinants of cellular sensitivity to FGF2-saporins.

Enhanced signaling and morphological transformation by a membrane-localized derivative of the fibroblast growth factor receptor 3 kinase domain

Fibroblast growth factor (FGF) receptors (FGFRs) are membrane-spanning tyrosine kinase receptors that mediate regulatory signals for cell proliferation and differentiation in response to FGFs. We have previously determined that the Lys650-->Glu mutation in the activation loop of the kinase domain of FGFR3, which is responsible for the lethal skeletal dysplasia thanatophoric dyplasia type II (TDII), greatly enhances the ligand-independent kinase activity of the receptor. Here, we demonstrate that expression of this construct induces a c-fos promoter construct approximately 10-fold but does not lead to proliferation or morphological transformation of NIH 3T3 cells. In contrast, the isolated kinase domain of activated FGFR3, targeted to the plasma membrane by a myristylation signal, is able to stimulate c-fos expression by 40-fold, induce proliferation of quiescent cells, and morphologically transform fibroblasts. This result suggests that the extracellular and transmembrane domains of FGFRs exert a negative regulatory influence on the activity of the kinase domain. Targeting of the activated kinase domain to either the cytoplasm or the nucleus does not significantly affect biological signaling, suggesting that signals from FGFR3 resulting in mitogenesis originate exclusively from the plasma membrane. Furthermore, our novel observation that expression of a highly activated FGFR3 kinase domain is able to morphologically transform fibroblasts suggests that dysregulation of FGFR3 has the potential to play a role in human neoplasia.

Fibroblast growth factor-1 induction of delayed-early mRNA expression in NIH 3T3 cells is prolonged by heparin addition

Fibroblast growth factor (FGF)-1, also known as acidic FGF, is a multifunctional heparin-binding protein that is mitogenic for a wide variety of cell types cultured in vitro and a potent angiogenic agent in vivo. These cellular responses are mediated via high-affinity binding to a family of four membrane-spanning tyrosine kinase receptors. FGF-1-stimulated mitogenesis is potentiated by heparin, a sulfated glycosaminoglycan. In this study, we examined the effect of exogenous heparin on FGF-1-inducible gene expression in murine NIH 3T3 cells using both wild-type FGF-1 and FGF-1/glu132, an FGF-1 mutant with a reduced apparent affinity for heparin. The induction levels and temporal expression kinetics of two immediate-early response mRNAs (early growth response gene-1, thrombospondin-1) as well as two delayed-early response mRNAs (proliferin, ornithine decarboxylase) were monitored by Northern blot hybridization analysis. We found that although FGF-1 alone can promote the initial induction of these four mRNAs, heparin coaddition is necessary for prolonged delayed-early mRNA expression. This heparin effect occurs when cells are stimulated with wild-type FGF-1 but not with FGF-1/glu132. Furthermore, FGF-1 and heparin must be added together at the initial time of mitogen stimulation and they must remain present in the cell culture medium for a minimum period of 8 h to promote sustained delayed-early mRNA expression. These findings are consistent with the proposal that heparin promotes a long-term FGF-1:FGFR interaction which is required for sustained delayed-early gene expression and a full mitogenic response.

Differential expression of the fibroblast growth factor receptor (FGFR) multigene family in normal human adult tissues

This report describes a systematic analysis of the expression of the fibroblast growth factor receptor (FGFR) multigene family (FGFR1, FGFR2, FGFR3, and FGFR4) in archival serial sections of normal human adult tissues representing the major organ systems, using immunohistochemical techniques. Polyclonal antisera specific for FGFR1, FGFR2, FGFR3, and FGFR4 and a three-stage immunoperoxidase technique were employed to determine the cellular distribution of these receptors at the protein level. The expression profiles for the tissue-specific cellular localization of the FGFR multigene family demonstrated wide-spread and striking differential patterns of expression of individual receptors in the epithelia and mesenchyme of multiple tissues (stomach, salivary glands, pancreas, thymus, ureter, and cornea) and co-expression of FGFR1-4 in the same cell types of other tissues. The wide-spread expression of FGFR1-4 in multiple organ systems suggests an important functional role in normal tissue homeostasis. Differences in the spatial patterns of FGFR gene expression may generate functional diversity in response to FGF-1 and FGF-2, both of which bind with equally high affinity to more than one receptor subtype. In vivo, this may lead to functional differences that are crucial for the regulation of normal physiological processes and are responsible for the pathological mechanisms that orchestrate various disease processes.

Gastric cancer associated with overexpression of parathyroid hormone-related peptide (PTHrP) and PTH/PTHrP receptor in relation to tumor progression

Parathyroid hormone-related peptide (PTHrP) is involved in cell proliferation in both neoplastic and non-neoplastic tissues. We describe an autopsy case of gastric cancer in a patient who showed serum hypercalcemia and overexpression of PTHrP and PTH/PTHrP receptor in the metastatic tumor cells. The primary gastric tumor was poorly differentiated adenocarcinoma, and multiple metastases were present in the bone, multiple visceral organs, peritoneum, and lymph nodes. PTHrP and its mRNA were detected only in the metastatic tumor cells, but not in primary gastric tumor. PTH/PTHrP receptor was also demonstrated immunohistologically in metastatic tumor cells. This case suggests that the expression of PTHrP is related to tumor progression and the poor prognosis in tumors associated with humoral hypercalcemia.