Fibroblast growth factor receptor 4 single nucleotide polymorphism Gly388Arg in head and neck carcinomas.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is considered to be a progressive disease resulting from alterations in multiple genes regulating cell proliferation and differentiation like receptor tyrosine kinases (RTKs) and members of the fibroblast growth factor receptors (FGFR)-family. Single-nucleotide polymorphism (SNP) Arg388 of the FGFR4 is associated with a reduced overall survival in patients with cancers of various types. We speculate that FGFR4 expression and SNP is associated with worse survival in patients with HSNCC. AIM: To investigate the potential clinical significance of FGFR4 Arg388 in the context of tumors arising in HNSCC, a comprehensive analysis of FGFR4 receptor expression and genotype in tumor tissues and correlated results with patients' clinical data in a large cohort of patients with HNSCC was conducted. METHODS: Surgical specimens from 284 patients with HNSCC were retrieved from the Institute of Pathology at the Ludwig-Maximilian-University in Germany. Specimens were analyzed using immunohistochemistry and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The expression of FGFR4 was analyzed in 284 surgical specimens of HNSCC using immunohistochemstry. FGFR4 polymorphism was detected by PCR-RFLP. Patients' clinical data with a minimum follow-up of 5 years were statistically evaluated with a special emphasis on survival analysis employing Kaplan-Meier estimator and Cox regression analysis. RESULTS: Concerning the invasive tumor areas the intensity of the FGFR4 expression was evaluated in a four-grade system: no expression, low expression, intermediate and high expression. FGFR4 expression was scored as "high" (+++) in 74 (26%), "intermediate" (++) in 103 (36.3%), and "low" (+) in 107 (36.7%) cases. Analyzing the FGFR4 mutation it was found in 96 tumors (33.8%), 84 of them (29.6%) having a heterozygous and 12 (4.2%) homozygous mutated Arg388 allele. The overall frequency concerning the mutant alleles demonstrated 65% vs 34% mutated alleles in general. FGFR4 Arg388 was significantly associated with advanced tumor stage (P < 0.004), local metastasis (P < 0.0001) and reduced disease-free survival (P < 0.01). Furthermore, increased expression of FGFR4 correlated significantly with worse overall survival (P < 0.003). CONCLUSION: In conclusion, the FGFR4 Arg388 genotype and protein expression of FGFR4 impacts tumor progression in patients with HNSCC and may present a useful target within a multimodal therapeutic intervention.

A single nucleotide change in the mouse genome accelerates breast cancer progression.

In the growth factor receptor gene FGFR4 the presence of the common single nucleotide polymorphism Arg388 has been associated with progression of various types of cancer including breast cancer. However, a causative relationship is not readily assigned due to genetic heterogeneity in different patient cohorts. To address this issue, we compared the effects of this allele on malignant progression in the WAP-TGFalpha transgenic mouse model of breast cancer. A knock-in strain was generated to introduce an analogous Arg385 allele into the murine FGFR4 gene. Mouse embryonic fibroblasts derived from this strain displayed accelerated cell transformation, with transformed cells exhibiting greater motility and invasive behavior. In the in vivo context of TGFalpha-induced mammary carcinogenesis, tumor development and progression was significantly advanced in tumor mass, size, and onset of pulmonary metastases. Our findings definitively identify the FGFR4 Arg388 allele as a functional prognostic marker for breast cancer progression.

Silencing of GRP94 expression promotes apoptosis in pancreatic cancer cells.

As a molecular chaperone, GRP94 is the most abundant glycoprotein in the endoplasmic reticulum, playing an important role in maintaining cellular homeostasis. Here, we investigated the expression and the role of GRP94 in regulating cell growth and apoptosis in pancreatic cancer cells. GRP94 mRNA levels were analyzed by QRT-PCR. Immunohistochemistry was performed to localize GRP94 in tissues of the normal pancreas (n=20), chronic pancreatitis (n=20) and pancreatic ductal adenocarcinoma (n=44). Silencing of GRP94 expression was carried out by transfection with specific siRNA oligonucleotides. Apoptosis was induced by treatment with actinomycin D. Compared to normal pancreatic tissues, median mRNA levels of GRP94 were 1.5- and 3.7-fold (p<0.05) lower in chronic pancreatitis and pancreatic cancer tissues, respectively. GRP94 protein was strongly expressed in normal acinar cells and moderately expressed in normal ductal cells. GRP94 expression was lost in 48% of the cancer cases. Moderate or strong staining in cancer cells was observed in 32 and 20% of pancreatic cancer tissues, respectively. Silencing GRP94 by siRNA increased apoptosis of pancreatic cancer cells in vitro. Patients with higher than the median expression have a tendency for a worsened survival. When the small number of patients with the highest expression (n=3) were compared with the rest of the group (n=41), the survival difference was significantly worse (5 vs. 18 months, respectively, p=0.006). Down-regulation of GRP94 decreases apoptosis resistance in pancreatic cancer cells. Clinically, patients with high GRP94 expression show a tendency for a worsened survival.

Confirmation of DNA microarray-derived differentially expressed genes in pancreatic cancer using quantitative RT-PCR.

The fact that pancreatic ductal adenocarcinoma (PDAC) is still an exceptionally lethal disease with an annual mortality almost equivalent to its annual incidence has stimulated intense research efforts directed at understanding the underlying molecular mechanisms. By enabling simultaneous expression analysis of thousands of genes, microarray technology has significantly contributed to illuminating the pathophysiology of PDAC. Gene expression profiling studies have been performed for molecular classification of clinically relevant tumor subtypes and have shed light on various signaling pathways associated with tumor progression. Altered expression levels of several genes have been identified as correlating with functional in vitro data as well as patient survival, indicating the potential clinical value of transcriptional profiling. However, broad clinical use of array techniques for patient characterization has been hampered by their cost intensity and by limited inter-study comparability. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR), as the most sensitive technique for mRNA detection and quantification, will complement arrays for the confirmation of individual transcripts in larger sample cohorts. This review highlights recent studies that addressed gene expression analysis with both methodologies and that identified components of the TGF-beta signaling pathway, BNIP3, or periostin to be differentially expressed in PDAC. These studies demonstrated that the combination of microarray and RT-PCR technologies is a highly efficient and reliable approach for the identification of clinically important diagnostic and prognostic biomarkers, as well as for the discovery of novel therapeutic target candidates.

Cancer-stellate cell interactions perpetuate the hypoxia-fibrosis cycle in pancreatic ductal adenocarcinoma.

BACKGROUND AND AIMS: Although both cancer and stellate cells (PSCs) secrete proangiogenic factors, pancreatic cancer is a scirrhous and hypoxic tumor. The impact of cancer-PSCs interactions on angiogenesis was analyzed. METHODS: Expression of periostin, CD31, and alpha-smooth muscle actin was assessed by immunohistochemistry. Human PSCs and cancer cells were cultivated under normoxia and hypoxia alone, or in coculture, to analyze the changes in their angiogenic and fibrogenic attributes, using enzyme-linked immunosorbent assay, immunoblot, and quantitative polymerase chain reaction analyses and growth of cultured endothelial cells in vitro. RESULTS: On the invasive front of the activated stroma, PSCs deposited a periostin-rich matrix around the capillaries in the periacinar spaces. Compared with the normal pancreas, there was a significant reduction in the microvessel density in chronic pancreatitis (five-fold, P < .001) and pancreatic cancer (four-fold, P < .01) tissues. In vitro, hypoxia increased PSCs' activity and doubled the secretion of periostin, type I collagen, fibronectin, and vascular endothelial growth factor (VEGF). Cancer cells induced VEGF secretion of PSCs (390 +/- 60%, P < .001), whereas PSCs increased the endostatin production of cancer cells (210 +/- 14%, P < .001) by matrix metalloproteinase-dependent cleavage. In vitro, PSCs increased the endothelial cell growth, whereas cancer cells alone, or their coculture with PSCs, suppressed it. CONCLUSIONS: Although PSCs are the dominant producers of VEGF and increase endothelial cell growth in vitro, in the peritumoral stroma, they contribute to the fibrotic/hypoxic milieu through abnormal extracellular matrix deposition and by amplifying endostatin production of cancer cells.

Northern blot analysis for detection and quantification of RNA in pancreatic cancer cells and tissues.

Investigation of gene expression significantly contributes to our knowledge of the regulation and function of genes in many areas of biology. In this protocol, we describe how northern blot analysis is used to identify gene expression patterns at the RNA level in human cancer cells as well as in cancerous and normal tissues. RNA molecules are separated by gel electrophoresis and are subsequently transferred to a porous membrane by capillary action. Specific sequences in the RNA are detected on the membrane by molecular hybridization with radiolabeled nucleic acid probes. Despite the development of newer methods, such as real-time PCR, nuclease protection assays and microarrays, northern blot analysis is still a standard technique used in the detection and quantification of mRNA levels because it allows a direct comparison of the mRNA abundance between samples on a single membrane. This entire northern blotting protocol takes approximately 4 d to complete.

Fibroblast growth factor receptor 4 regulates proliferation, anti-apoptosis and alpha-fetoprotein secretion during hepatocellular carcinoma progression and represents a potential target for therapeutic intervention.

BACKGROUND/AIMS: FGFR4, a member of the fibroblast growth factor receptor family, has been recently associated with progression of melanoma, breast and head and neck carcinoma. Given its uniquely high expression in the liver, we investigated its contributory role to hepatocellular carcinoma (HCC). METHODS: We performed a comprehensive sequencing of full-length FGFR4 transcript in 57 tumor/normal HCC tissue pairs, and quantified their mRNA expressions. Notable mutations and expression patterns were correlated with patient data. Clinically significant trends were examined in in vitro models. RESULTS: We found eight genetic alterations including two highly frequent polymorphisms (V10I and G338R). Secretion of alpha-fetoprotein (AFP), a HCC biomarker, was increased among patients bearing homozygous Arg388 alleles. One-third of these patients exhibited increased FGFR4 mRNA expression in the matched tumor/normal tissue. Subsequent in vitro perturbation of FGFR4 signaling through both FGF19-stimulation and FGFR4 silencing confirmed a mechanistic link between FGFR4 activities and tumor aggressiveness. More importantly, inhibition of FGFR activity with PD173074 exquisitely blocked HuH7 (high FGFR4 expression) proliferation as compared to control cell lines. CONCLUSIONS: FGFR4 contributes significantly to HCC progression by modulating AFP secretion, proliferation and anti-apoptosis. Its frequent overexpression in patients renders its inhibition a novel and much needed pharmacological approach against HCC.

Hypoxia-inducible proto-oncogene Pim-1 is a prognostic marker in pancreatic ductal adenocarcinoma.

BACKGROUND: Pim-1 is a proto-oncogene involved in cell survival, differentiation and proliferation in several hematologic and epithelial malignancies. Clinically, absence of Pim-1 expression correlates with poor prognosis in prostate cancer. In the present study, the expression of Pim-1 is analyzed in pancreatic cancer and correlated to clinicopathological parameters. RESULTS: Compared to benign, inflammatory and pre-malignant conditions (i.e., the normal pancreas, chronic pancreatitis and benign intraductal papillary mucinous neoplasm), expression of Pim-1 mRNA and protein increased significantly in pancreatic malignancies. Absence of Pim-1 immunopositivity in cancer cells strongly correlated with a poor prognosis (median survival 13.8 vs. 23.4 months, p = 0.0016). In vitro, rapidly dividing (high versus low serum concentrations) and hypoxic cells displayed higher Pim-1 mRNA and protein levels. METHODS: Pim-1 mRNA and protein was evaluated with quantitative real-time RT-PCR, immunofluorescence and immunocytochemistry analyses. Ex vivo expression analysis using semi-quantitative immunohistochemistry was performed using human pancreatic tissues of the normal pancreas (n = 10), chronic pancreatitis (n = 30), pancreatic ductal adenocarcinoma (n = 59) and other pancreatic tumors (n = 42). In consecutive sections HIF1-alpha was used as a marker of hypoxia. Survival of patients (n = 35) was compared using the Kaplan-Meier method and a log-rank test. In vitro analyses were performed using cultured pancreatic cancer cell lines (n = 8) and primary human pancreatic stellate cells. CONCLUSION: Hypoxia is a novel inducer of Pim-1 expression. Compared to non-malignant tissues Pim-1 significantly increases in pancreatic cancer. However, the presence of Pim-1 in cancer cells has a positive prognostic impact.

Genetic alterations in the tyrosine kinase transcriptome of human cancer cell lines.

Protein tyrosine kinases (PTKs) play a critical role in the manifestation of cancer cell properties, and respective signaling mechanisms have been studied extensively on immortalized tumor cells. To characterize and analyze commonly used cancer cell lines with regard to variations in the primary structure of all expressed PTKs, we conducted a cDNA-based sequence analysis of the entire tyrosine kinase transcriptome of 254 established tumor cell lines. The profiles of cell line intrinsic PTK transcript alterations and the evaluation of 155 identified polymorphisms and 234 somatic mutations are made available in a database designated "Tykiva" (tyrosine kinome variant). Tissue distribution analysis and/or the localization within defined protein domains indicate functional relevance of several genetic alterations. The cysteine replacement of the highly conserved Y367 residue in fibroblast growth factor receptor 4 or the Q26X nonsense mutation in the tumor-suppressor kinase CSK are examples, and may contribute to cell line-specific signaling characteristics and tumor progression. Moreover, known variants, such as epidermal growth factor receptor G719S, that were shown to mediate anticancer drug sensitivity could be detected in other than the previously reported tumor types. Our data therefore provide extensive system information for the design and interpretation of cell line-based cancer research, and may stimulate further investigations into broader clinical applications of current cancer therapeutics.

PTP-PEST phosphatase variations in human cancer.

Signal transduction via tyrosine phosphorylation, normally fine-tuned by the concerted action of both protein tyrosine kinases and protein tyrosine phosphatases (PTPs), is a key mechanism in tumorigenesis. PTP-PEST, a ubiquitously expressed cytoplasmic tyrosine phosphatase, is thought to play an important role in cell adhesion and motility, and may be involved in metastasis. A search for sequence variations within the gene PTPN12 (alias PTP-PEST) was performed in breast cancer cell lines, leading to the identification of three amino acid substitutions at positions 322, 573, and 709. These alterations were also found in squamous cell carcinoma cell lines and could be verified in primary human breast and kidney tumor samples. Analysis of peripheral blood samples confirmed the germline origin of these alterations. Furthermore, functional characterization of the Ile322 and Ala573 PTP-PEST mutants revealed an enhancement of in vitro phosphatase activity, whereas the Lys709 variant showed reduced catalytic activity. These data demonstrate the existence of PTP-PEST variants that might be meaningful for human cancer and underscore the need for further characterizing PTP-PEST and its signaling pathways in context of this disease.

FGFR4 Arg388 allele is associated with resistance to adjuvant therapy in primary breast cancer.

PURPOSE: A recent study presented first evidence that a single nucleotide polymorphism (SNP) at codon 388 of fibroblast growth factor receptor 4 (FGFR4) gene, causing a transmembrane domain missense mutation (Gly388Arg), is associated with disease outcome in node-positive breast cancer. This article addresses the clinical relevance of this SNP, FGFR4 genotype, phenotype, and HER2 regarding patient outcome and influence of adjuvant systemic therapy in a substantial primary breast cancer collective (n = 372; median follow-up, 94.5 months). METHODS: Polymerase chain reaction restriction fragment length polymorphism analysis of germ-line polymorphism was performed in uninvolved lymph nodes; FGFR4 and HER2 expression were assessed immunohistochemically in tissue microarrays. RESULTS: In 51% of patients, homo- or heterozygous Arg388 allele was present. No correlation existed between FGFR4 genotype and expression or HER2 status. In node-negative patients, FGFR4 genotype was not correlated with disease outcome. In node-positive patients, however, FGFR4 Arg388 was significantly associated with poor disease-free survival (DFS; P = .02) and overall survival (OS; P = .04). Notably, this association seems to be attributable to relatively poor therapy response in Arg388 carriers, reflected in their significantly shorter DFS (P = .02) and OS (P = .045) among patients receiving adjuvant systemic therapy. It is also seen as a significant interaction term in a multivariate proportional hazards model with Arg388 carriers having only about half as much benefit from adjuvant systemic therapy as wild-type carriers. CONCLUSION: According to this study, FGFR4 Arg388 genotype is a marker for breast cancer progression in patients with adjuvant systemic therapy, particularly chemotherapy, and thus may indicate therapy resistance.

EGFR signaling leads to downregulation of PTP-LAR via TACE-mediated proteolytic processing.

Proteolytic processing and ectodomain shedding have been described for a broad spectrum of transmembrane proteins under both normal and pathophysiological conditions and has been suggested as one mechanism to regulate a protein's function. It has also been documented for the receptor-like protein tyrosine phosphatase PTP-LAR, induced by treating cells with the tumor promoter TPA or the calcium ionophor A23187. Here we identified the epidermal growth factor receptor (EGFR) as both an association partner of PTP-LAR, that mediates phosphorylation of the latter, as well as an inducer of LAR-cleavage. Both overexpression of this kinase and stimulation of endogenous EGFR in various tumor cell lines were shown to induce proteolytic processing of the catalytic LAR-P-subunit. In contrast to TPA-induced shedding of PTP-LAR, EGFR-mediated cleavage did not require PKC-activity. For both stimuli, however, processing of the P-subunit turned out to be dependent on the activation of the MAP kinases ERK1 and ERK2, and was completely abrogated upon pre-treating cells with Batimastat, indicating the involvement of a metalloproteinase in this pathway. Being strongly impaired in fibroblasts derived from ADAM-17/TACE-knockout-mice or tumor cells that express a dominant negative mutant of ADAM-17/TACE, cleavage of PTP-LAR is suggested to be mediated by this metalloproteinase. Paralleled by rapid reduction of cell surface-localized LAR-E-subunit, EGFR-induced cleavage could be shown to lead to degradation of the catalytic LAR-P-subunit, thereby resulting in a significantly reduced overall cellular phosphatase activity of PTP-LAR. These results for the first time identify a protein tyrosine phosphatase as a potential substrate of TACE and describe proteolytic processing of PTP-LAR as a means of regulating phosphatase activity downstream and thus under the control of EGFR-mediated signaling pathways.

Involvement of the FGFR4 Arg388 allele in head and neck squamous cell carcinoma.

Fibroblast growth factor receptors (FGFRs) have been implicated in various forms of human hyperproliferative disorders such as cancers of the cervix and bladder. We investigated the expression pattern of FGFR4 and the clinical significance of the recently identified Gly/Arg polymorphism (388) in head and neck squamous cell carcinomas (HNSCCs) of the oral cavity and the oropharynx. Sections from 104 paraffin-embedded tumors were analyzed by a restriction fragment length polymorphism-based method to determine the FGFR4 genotypes. Protein expression was investigated immunohistochemically and graded into a low, intermediate, or high degree of staining. FGFR4 expression was scored as high in 17, as intermediate in 59 and as low in 28 cases. The FGFR4 Arg388 allele was found in 59 tumors, 46 of them having heterozygous and 13 homozygous genotypes. High expression of the FGFR4 Arg388 allele was significantly associated with reduced overall survival (p = 0.032) and with an advanced tumor stage (p = 0.023), whereas expression of the FGFR4 Gly388 had no impact on disease progression. Our findings indicate that high expression of FGFR4 in connection with the Arg388 allele is associated with poor clinical outcome and support the significance of FGFR4 as a diagnostic marker and a target for therapeutic intervention in human HNSCC.

Beyond Herceptin and Gleevec.

Identification of the key role of protein kinases as potential oncoproteins has led to the emergence of a new era of target-directed therapies. Among a variety of novel therapeutic strategies two have shown the most promise and led to a variety of therapeutic agents in clinical development. One approach utilises humanised monoclonal antibodies generated against the extracellular domain of transmembrane protein kinases. The second approach is the generation of small molecule ATP analogues targeting the kinase domain itself. The approval of agents such as Herceptin for the treatment of advanced breast cancer and Gleevec for chronic myelogenous leukemia and gastrointestinal stromal tumours are the first examples of gene-based cancer drugs and represent the first example of a novel strategy in anti-cancer therapy.