Biomedical subjects

Murray Korc

Publications and source records attributed to Murray Korc.

41 records · Page 3Linked to original sources

PubMed2002

Targeting of suicide gene delivery in pancreatic cancer cells via FGF receptors.

Pancreatic ductal adenocarcinomas (PDACs) overexpress various cell-surface tyrosine kinase receptors, including the type I high-affinity fibroblast growth factor receptor (FGFR-1). The purpose of this study was to determine whether FGFR-targeted gene therapy is feasible in this disorder. Accordingly, the effects of a conjugate consisting of fibroblast growth factor (FGF)-2 linked to a Fab' fragment against the adenovirus knob region were evaluated in human pancreatic cancer cell lines treated with an adenoviral vector containing the herpes simplex virus thymidine kinase (AdTK) gene. An adenoviral vector containing the firefly luciferase reporter gene (AdLuc) served to assess infection efficiency, and was initially tested in L6 rat myoblasts. In parental L6 cells that express exceedingly low levels of high-affinity FGFRs, transduction with AdLuc was enhanced 7- to 10-fold with the FGF2-Fab' conjugate, whereas in L6 cells transfected to express FGFR-1, it was enhanced 39- to 52-fold. The pancreatic cancer cell lines expressed variable levels of the four high-affinity FGF receptors, and exhibited 2- to 34-fold increases in gene transduction in the presence of the FGF2-Fab' conjugate. In the absence of FGF2-Fab' there was no correlation between surface binding of FGF2 and AdLuc transduction efficiency, whereas in the presence of FGF2-Fab', enhanced AdLuc transduction efficiency correlated with greater surface binding of FGF2. In the absence of AdTK, all the cell lines were insensitive to ganciclovir, whereas after AdTK transduction, only ASPC-1 and PANC-1 cells were resistant to ganciclovir even in the presence of FGF2-Fab'. Ganciclovir-mediated inhibition was dependent on the conjugate in CAPAN-1 and COLO-357 cells, but was independent of the conjugate in T3M4 and MIA-PaCa-2 cells. Real-time quantitative PCR of laser-captured cancer cells revealed high levels of various FGFR mRNA species in six of seven PDAC tumor samples. These findings indicate that transduction efficiency with FGF2-Fab' in pancreatic cancer cells is independent of native adenoviral transduction efficiency and is greatest in cells that exhibit concomitant expression of various high-affinity FGFRs. In view of the overexpression of high-affinity FGFRs in the cancer cells in PDAC, our findings also suggest that the combined use of AdTK, ganciclovir, and FGF2-Fab' may ultimately be a promising therapeutic approach in a subgroup of patients with PDAC.

Adenocarcinoma↗

PubMed2002

IIIc isoform of fibroblast growth factor receptor 1 is overexpressed in human pancreatic cancer and enhances tumorigenicity of hamster ductal cells.

BACKGROUND & AIMS: Fibroblast growth factors (FGFs) are mitogenic polypeptides that signal via FGF receptors (FGFRs). Pancreatic ductal adenocarcinomas (PDACs) overexpress multiple FGFs, implying a potential for growth modulation. In this study we investigated the importance of the IIIc splice variant of FGFR-1 (FGFR-1 IIIc) in PDAC. METHODS: Expression of FGFR-1 IIIc was determined by a ribonuclease protection assay in pancreatic cancer cell lines and in tissues. In situ hybridization was used to localize FGFR-1 IIIc messenger RNA (mRNA) in pancreatic tissues. A cDNA encoding FGFR-1 IIIc was stably transfected into the well-differentiated TAKA-1 pancreatic ductal cell line that is not responsive to FGF5 and does not express FGFR-1. RESULTS: FGFR-1 IIIc was expressed in 5 of 7 pancreatic cancer cell lines and in the majority of the cancer cells in 4 of 7 PDAC samples. In vitro, TAKA-1 cells stably transfected with FGFR-1 IIIc exhibited increased basal growth; enhanced basal tyrosine phosphorylation of FGFR substrate-2 (FRS2), Shc, and phospholipase Cgamma; and increased activation of mitogen-activated protein kinase (MAPK). PD98059, an inhibitor of MAPK, suppressed the basal growth of parental and transfected clones, but the effect was more marked in clones expressing FGFR-1 IIIc. In vivo, tumor formation in nude mice was dramatically enhanced with FGFR-1 IIIc transfected (20 of 20) in comparison with sham transfected (0 of 10) cells. CONCLUSIONS: Our data indicate that FGFR-1 IIIc is expressed in human pancreatic cancer cells, promotes mitogenic signaling via the FRS2-MAPK pathway, and has the potential to enhance pancreatic ductal cell transformation.

Adult↗

PubMed2002

Connective tissue growth factor is involved in pancreatic repair and tissue remodeling in human and rat acute necrotizing pancreatitis.

OBJECTIVE: To analyze the involvement of connective tissue growth factor (CTGF) in the transforming growth factor-beta (TGF-beta) pathway during acute necrotizing pancreatitis (ANP) in humans and rats. SUMMARY BACKGROUND DATA: Connective tissue growth factor is involved in several fibrotic diseases and has a critical role in fibrogenesis and tissue remodeling after injury. METHODS: Normal human pancreas tissue samples were obtained through an organ donor program from five individuals without a history of pancreatic disease. Human ANP tissues were obtained from eight persons undergoing surgery for this disease. In rats, ANP was induced by intraductal infusion of taurocholate. The expression of CTGF was studied by Northern blot analysis, in situ hybridization, and immunohistochemistry in both human and rat pancreatic tissue samples. RESULTS: Northern blot analysis revealed enhanced CTGF mRNA expression in human ANP tissue samples compared with normal controls. In addition, a concomitant increase in TGF-beta1 was present. By in situ hybridization, CTGF mRNA was localized in the remaining acinar and ductal cells and in fibroblasts. In regions of intense damage adjacent to areas of necrosis, CTGF mRNA signals were most intense. Inflammatory cells were devoid of any CTGF mRNA signals. By immunohistochemistry, CTGF protein was localized at high levels in the same cell types as CTGF mRNA. In ANP in rats, concomitantly enhanced mRNA levels of CTGF, TGF-beta1, and collagen type 1 were present, with a biphasic peak pattern on days 2 to 3 and day 7 after induction of ANP. CONCLUSIONS: These data indicate that CTGF participates in tissue remodeling in ANP. The expression of CTGF predominantly in the remaining acinar and ductal cells indicates that extracellular matrix synthesis after necrosis is at least partly regulated by the remaining pancreatic parenchyma and only to a minor extent by inflammatory cells. Blockage of CTGF, a downstream mediator of TGF-beta in fibrogenesis, might be useful as a target to influence and reduce fibrogenesis in this disorder.

Adult↗

PubMed2002

Soluble type II transforming growth factor-beta receptor attenuates expression of metastasis-associated genes and suppresses pancreatic cancer cell metastasis.

Pancreatic ductal adenocarcinoma (PDAC) is a deadly malignancy that frequently metastasizes and that overexpresses transforming growth factor-beta s (TGF-beta s). To determine whether TGF-beta s can act to enhance the metastatic potential of PDAC, PANC-1 human pancreatic cancer cells were transfected with an expression construct encoding a soluble type II TGF-beta receptor (sT beta RII) that blocks cellular responsiveness to TGF-beta 1. When injected s.c. in athymic mice, PANC-1 clones expressing sT beta RII exhibited decreased tumor growth in comparison with sham-transfected cells and attenuated expression of plasminogen activator inhibitor 1 (PAI-1), a gene associated with tumor growth. When tested in an orthotopic mouse model, these clones formed small intrapancreatic tumors that exhibited a suppressed metastatic capacity and decreased expression of plasminogen activator inhibitor 1 and the metastasis-associated urokinase plasminogen activator. These results indicate that TGF-beta s act in vivo to enhance the expression of genes that promote the growth and metastasis of pancreatic cancer cells and suggest that sT beta RII may ultimately have a therapeutic benefit in PDAC.

Animals↗

PubMed2001

Expression of the IIIc Variant of FGF Receptor-1 Confers Mitogenic Responsiveness to Heparin and FGF-5 in TAKA-1 Pancreatic Ductal Cells.

Human pancreatic cancer is a devastating diseasewith a poor prognosis (1). Although the exact reasonsfor the aggressive nature of this disorder are unknown, certain observations have pointed to theimportant role of growth factors in its pathobiology(2). Many of these cancers frequently overexpressfibroblast growth factors (FGFs) (3). FGF signalingis mediated through four high-affinity tyrosine kinasereceptors, termed fibroblast growth-factor receptors(FGFRs) (3,4). The extracellular domain of FGFRsis usually composed of three immunoglobulin (Ig)-like domains (I-III), a transmembrane region followedby a juxtamembrane domain, and a splittyrosine kinase catalytic domain. Several isoformsof FGFR-1, -2, and -3 have been identified, some of which exhibit different ligand-binding properties(3,5). Alternative splicing of the second half of Igdomain III of FGFR-1 results in three receptor variants,termed IIIa, IIIb, and IIIc. The IIIa splice variantyields a secreted receptor that is devoid of anysignaling capacity (5). The expression of the IIIbvariant is generally restricted to epithelial cell types,whereas the expression of the IIIc variant is restrictedto mesenchymal cell types (6-11).

Journal Article↗