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At least 289 records · Page 16Linked to original sources
PubMed2006

In vitro developmental competence of pig nuclear transferred embryos: effects of GFP transfection, refrigeration, cell cycle synchronization and shapes of donor cells.

The present study was designed to evaluate the feasibility of producing pig transgenic blastocysts expressing enhanced green fluorescent protein (GFP) and to examine the effects of shape and preparation methods of donor cells on in vitro developmental ability of pig nuclear transferred embryos (NTEs). In experiment 1, the effect of GFP transfection on development of pig NTEs was evaluated. The cleavage and blastocyst rates showed no significant difference between NTEs derived from transfected and non-transfected donors. In experiment 2, the effect of different nuclear donor preparation methods on in vitro development of NTEs was examined. The cleavage rate showed no statistically significant differences among three preparation methods. The blastocyst rates of donor cells treated once at -4 degrees C and those of freshly digested cells were similar to each other (26.3% vs 17.9%). The lowest blastocyst rates (5.88%) were observed when cells cryopreserved at -196 degrees C were used as donors. In experiment 3, the effect of different cell cycle synchronization methods on the in vitro development potential of pig NTEs was evaluated. The cleavage rate of NTEs derived from cycling cells was much better than that of NTEs derived from serum-starved cells (64.4% vs 50.5%, p < 0.05), but no significant difference was observed between the the blastocyst rates of the two groups. In experiment 4, the effect of different shapes of cultured fibroblast cells on the in vitro development of pig NTEs was examined. The fusion rate for couplets derived from rough cells was poorer than that observed in couplets derived from round smooth cells (47.8% vs 76.8%, p < 0.05). However, there were no significant differences observed in the cleavage rate and blastocyst rate. In conclusion, the present study indicated that (i) refrigerated pig GFP-transfected cells could be used as donors in nuclear transfer and these NTEs could be effectively developed to blastocyst stage; (ii) serum starvation of GFP-transfected cells is not required for preimplantation development of pig NTEs; and (iii) a rough surface of GFP-transfected donor cells affects fusion rate negatively but has no influence on the cleavage rate or blastocyst rate of pig NTEs.

Animals↗
PubMedDate not supplied

Production of GFP and glucoamylase by recombinant Aspergillus niger: effects of fermentation conditions on fungal morphology and protein secretion.

The effect of filamentous fungal morphology on heterologous protein secretion was investigated using the recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP], which contained the gene coded for the GLA-GFP (glucoamylase-green fluorescence protein) fusion protein. Three culturing systems were studied to develop different morphological forms of the fungus. Free-cell cultures in conventional stirred-tank bioreactors grew in pellet form with various sizes depending on culturing conditions. Cells immobilized on cotton cloth grew in mycelial form in a rotating fibrous bed (RFB) and a static fibrous bed (SFB) bioreactors. The expression of the fusion protein was growth-associated and dependent on the fungal morphology. Immobilized cells produced 10-fold more GFP and glucoamylase than well-oxygenated free-cell pellets. In free-cell cultures, excretion of the fusion protein occurred mainly from cell autolysis, when oxygen or nutrient were depleted, whereas protein secretion took place from the beginning of the fermentation in immobilized-cell cultures. Also, protein secretion was found to be strongly dependent on morphology. Small pellets of a 1-mm size secreted 82% of GFP produced, whereas 43% of GFP remained intracellular in larger pellets of 5 mm. Complete secretion of GFP was obtained with cells immobilized on the fibrous matrix. The improvement in heterologous protein synthesis and secretion can be attributed to the filamentous mycelial morphology since protein secretion occurred predominantly at the tips of growing hyphae. Secretion of proteases occurred mainly in the stationary phase or when cell autolysis were induced by nutrient depletion and was not dependent on morphology, although immobilizing the cells also reduced protease activity. The RFB bioreactor gave the best fermentation performance because of its ability to control the cell morphology that was amenable to efficient oxygen transfer and protein secretion.

Aspergillus niger↗
PubMedDate not supplied

Study of adenovirus production in serum-free 293SF suspension culture by GFP-expression monitoring.

The red-shifted S65T mutant green fluorescent protein (GFP) was used to compare the adenovirus (Ad) production and post-infection survival of 293SF and 293S cells in serum-free and serum-containing flask cultures, respectively. The GFP-expressing vector permitted the quantification of both the level of GFP expressed by infected cells and the infectious viral content of the cultures by flow cytometry in a simple, fast, sensitive, and reliable way. The GFP has the main advantage of fluorescing without any substrate addition. Infected cultures showed the coexistence of two populations of fluorescent cells, high-fluorescence cells (HFCs) and low-flourescence cells (LFCs), in proportions that varied between 20 and 75 hpi. The gradual increase in the number of LFCs at the expense of HFCs correlated well with the increase in the number of dead cells. This relationship could be used for the continuous measure of a culture's viability with the appropriate on-line instrumentation. The post-infection death rate of infected 293SF cells was higher than that of infected 293S cells, but the level of GFP fluorescence in viable, highly fluorescent cells was similar in the two infected cell lines. The number of infectious viral particles (IVPs) was quantified in less than 24 h by an infection assay of 293S cells in wells with viral particles extracted from the culture samples, and the results were more reproducible (+/- 10% variation) than those generally reported for conventional plaque assay titrations or end-point dilutions. The viable cell-specific IVP concentrations were for most experiments similar, indicating again that the difference between the two cell lines was their unequal post-infection viabilities, not the virus production by the infected living cells.

Adenoviridae↗
PubMed2001

Uniform GFP-expression in transgenic medaka (Oryzias latipes) at the F0 generation.

A green fluorescent protein (GFP) cDNA flanked by inverted terminal repeats (ITR) of adeno-associated virus was constructed. The construct sharply improved the efficiency and specificity of the transient expression of genes driven by two general promoters (cytomegalovirus and medaka beta-actin) and one muscle-specific promoter (zebrafish alpha-actin) in transgenic medaka. In addition, treatment with ITR sequence-containing constructs resulted in a dramatic increase in the number of embryos showing uniform GFP-expression at F0. Of the GFP-positive embryos, 34.6% (81/234), 10% (10/60), and 18% (38/212) showed homogenous GFP-expression for the derivative constructs of the cytomegalovirus, alpha-actin, and beta-actin promoters, respectively. As a result of uniform GFP-expression, green fluorescence in founders was (a) extended for an entire lifetime without degradation, and (b) transmitted as a genetic trait to F1 and F2 progeny of some transgenic lines via Mendelian inheritance. A Southern blot analysis revealed a random integration of the transgene into the genome of founders and progeny in both head-to-tail and tail-to-tail concatemerization patterns. Interestingly, some transgenic medaka with uniform and strong fluorescence could be visually noticeable to the unaided eye.

Actins↗
PubMed2003

GFP-transfected tumor cells are useful in examining early metastasis in vivo, but immune reaction precludes long-term tumor development studies in immunocompetent mice.

To develop effective therapeutic strategies aimed at treating tumor metastasis, critical steps in this process must be better understood. For this purpose we have established a new model to visualize and quantify early metastasis. Murine CT-26 colon adenocarcinoma cells were stably transfected with green fluorescent protein (GFP). Tumor cells were intraportally delivered to the liver of Balb/c mice and subsequently tracked by intravital fluorescence microscopy. Coinjection of fluorescent beads and in vivo propidium iodide staining allowed examination of initial tumor cell arrest, extravasation, viability and proliferation. Results showed that GFP-transfection compared to conventional labeling procedures (Calcein, cytoplasmic microspheres) did not alter early metastatic properties. However, the long-term development of liver metastases expressing GFP was markedly reduced compared to wild type CT-26 tumor cells. An increase in the size and the number of liver metastases in T- and B-cell-deficient SCID mice suggested an immune response to the GFP transfected cells responsible for the reduced metastatic growth in wild-type mice. Based on our findings, this model can be used to examine the early steps of metastasis in vivo. However, in immunocompetent mice, the use of GFP-labeled tumor cells should be limited to tracking cell arrest and extravasation, whereas evaluations of long-term metastatic growth should be performed in immunodeficient mice.

Adenocarcinoma↗
PubMed2004

Degradation of GFP-labelled POM121, a non-invasive sensor of nuclear apoptosis, precedes clustering of nuclear pores and externalisation of phosphatidylserine.

The nuclear pore membrane protein POM121 is specifically degraded during apoptosis by a caspase-3-dependent process enabling early detection of apoptosis in living cells expressing POM121-GFP. Here we further investigated temporal aspects of apoptotic degradation of POM121-GFP. We demonstrate that decreased POM121-GFP fluorescence precedes annexin V-labelling of apoptotic cells. This indicates that degradation of the nuclear pore complex starts prior to redistribution of plasma membrane phosphatidylserine, which serves as a signal for phagocytotic elimination of apoptotic cells. Furthermore, a caspase-resistant GFP-labelled mutant of POM121 resisted degradation even in late apoptosis and was detected in clustered nuclear pores. Thus, it can be concluded that loss of POM121-GFP is a specific sensor of the activation of caspase-3-dependent proteolysis at the nuclear pores.

Animals↗
PubMed2000

Melanophore lineage and clonal organization of the epidermis in Xenopus embryos as revealed by expression of a biogenic marker, GFP.

Melanophore lineage during embryogenesis of Xenopus laevis was traced using the overexpression of a biogenic marker, green fluorescent protein (GFP). Two different approaches were applied after injection of GFP mRNA (hence a marker construct) into each blastomere at the 16-cell stage. In in vivo experiments, the embryos injected with a marker construct were grown until stage 45, in which melanophores were distributed over the whole body and were good enough for checking GFP expression at their migratory destination. In in vitro experiments, neural tubes of the embryos injected with a marker construct were isolated and cultured at stage 21 to examine by virtue of GFP expression how neural crest cells differentiate into melanophores. The results obtained from both in vivo and in vitro experiments indicated the following: 1) selected animal blastomeres vastly contribute to the development of melanophores, whereas other animal blastomeres do so slightly at a limited pace; and 2) vegetal blastomeres never contribute to melanophores in normal development, whereas certain vegetal blastomeres have a potential to give rise to melanophores in vitro. The analyses using GFP also disclosed that the dorsal and ventral epidermis derive from the restricted animal blastomeres in the normal development. Since the dorso-ventrality of the epidermis has been inseparably coupled with integumental pigmentation, the clonal organization of the epidermis observed in the present study is discussed in the light of pigment pattern formation attributed by melanophores.

Animals↗
PubMed2002

Induction of autophagy causes dramatic changes in the subcellular distribution of GFP-Rab24.

Rab GTPases comprises a large family of proteins, with more than 50 gene products localized in distinct subcellular compartments. Rab24 is a member of this family whose function is not presently known. In order to elucidate the role of this protein we have generated a GFP-tagged Rab24 and studied the distribution of this chimera by fluorescence microscopy. GFP-Rab24 showed a perinuclear reticular localization that often encircled the nucleus. This reticular pattern partially overlapped with ER markers, cis-Golgi, and the ER-Golgi intermediate compartment. Surprisingly, when GFP-Rab24-transfected cells were starved to induce autophagy the distribution of the protein changed dramatically. GFP-Rab24 localized in large dots, cup-shaped structures and ring-shaped vesicles. Some of these vesicles were labeled with monodansylcadaverine, a specific autophagosome marker. In the presence of vinblastine, an agent that induces the formation of very large autophagic vesicles, GFP-Rab24 accumulated in the large vacuoles that were also labeled by monodansylcadaverine. Furthermore, Rab24 colocalized with LC3, a mammalian homolog of the yeast protein Apg8/Aut7, an essential gene for autophagy. This is the first report indicating that Rab24 localizes on autophagosomes, suggesting that this Rab protein is involved in the autophagic pathway.

Androstadienes↗
PubMed1998

Pure populations of transduced primary human cells can be produced using GFP expressing herpes virus vectors and flow cytometry.

Herpes simplex virus (HSV) has often been suggested as a vector for gene delivery to the nervous system although it is also capable of infecting many other cell types. HSV also has the ability to package large genetic insertions so the expression of multiple genes from a single virus is possible. Here we show that a green fluorescent protein (GFP) expressing HSV1 vector can transduce two primary human cell types--quiescent human CD34+ hematopoietic progenitor cells and dendritic cells--which are both hard to transduce by other means. We also show that GFP is an effective marker when expressed from an HSV vector in vivo in the mouse brain. When GFP is expressed together with a second gene (in this case lacZ) from a single virus, transduced GFP-positive CD34+ hematopoietic progenitor cells or dendritic cells can both be generated at an effective efficiency of 100% for the second gene. Here transduction with the vector is combined with flow cytometry allowing GFP-positive cells to be sorted from the untransduced population. Such completely transduced populations of quiescent CD34+ hematopoietic progenitor and dendritic cells cannot easily be achieved by other means, and might thus allow experimental or therapeutic protocols to be carried out requiring high-level transduction which would not otherwise be possible. Such an approach using HSV vectors might also be applicable to other cell types for which transduction is as yet unreliable or of low efficiency.

Animals↗
PubMed2005

GFP-PCNA as an S-phase marker in embryos during the first and subsequent cell cycles.

BACKGROUND INFORMATION: Proliferating cell nuclear antigen (PCNA) is a key component of the DNA replication machinery involved in the process of DNA elongation, recombination, methylation and repair. We have used PCNA fused with green fluorescent protein (GFP-PCNA) as a convenient tool to show the progress of S-phase in single embryos in vivo. Here we make a comparison between Hoechst 33342 and GFP-PCNA as in vivo event markers for DNA synthesis. Hoechst 33342 and DAPI (4,6-diamidino-2-phenylindole) have been used as a simple and rapid method for assessing membrane permeability and staining DNA in mammalian cells. However, it is difficult to use these dyes in living embryos during cell cycle progression studies over long periods of time as they are phototoxic. Moreover, though Hoechst staining reveals nuclear morphology, it gives no information about the progress of S-phase. RESULTS: We have microinjected or expressed a GFP-PCNA chimera to develop a method which enables visualization of S-phase in sea urchin and Caenorhabditis elegans embryos during the first and subsequent embryonic cell cycles and in Drosophila stage 4 embryos during syncytial nuclear divisions. We find that nuclear accumulation of GFP-PCNA correlates with S-phase onset. Loss of the chimera from the nucleus occurs when the nuclear envelope breaks down at mitosis. CONCLUSIONS: GFP-PCNA is a accurate and non-toxic marker of S-phase in embryos during early development.

Animals↗
PubMed1999

The assembly and migration of SeqA-Gfp fusion in living cells of Escherichia coli.

SeqA protein, which binds to hemi-methylated GATC sequences of DNA, is localized to discrete fluorescent foci in wild-type Escherichia coli cells. In this work, we observed cellular localization of the SeqA-Gfp fusion in living cells. SeqA-Gfp was localized to a discrete focus or foci in wild-type and seqA null mutant cells, but the fusion was dispersed in the whole cell in dam null mutant cells lacking Dam methyltransferase. These results were consistent with the previous description of the localization of SeqA by immunofluorescence microscopy. Time-lapse experiments revealed that duplicated SeqA-Gfp foci migrated rapidly in opposite directions. Flow cytometry demonstrated that the fusion restored synchronous replication of chromosomal DNA from multiple origins in seqA null mutant cells, indicating that SeqA-Gfp is biologically active. Immunoprecipitation of the fusion from cell extracts using anti-Gfp antibody indicated that the fusion was assembled with the wild-type SeqA protein.

Bacterial Outer Membrane Proteins↗
PubMed1998

A GFP-mouse talin fusion protein labels plant actin filaments in vivo and visualizes the actin cytoskeleton in growing pollen tubes.

The C-terminus of mouse talin (amino acids 2345-2541) is responsible for all of the protein's f-actin binding capacity. Unlike full-length talin, the C-terminal f-actin binding domain is unable to nucleate actin polymerization. We have found that transient and stable expression of the talin actin-binding domain fused to the C-terminus of the green fluorescent protein (GFP-mTn) can visualize the actin cytoskeleton in different types of living plant cells without affecting cell morphology or function. Transiently expressed GFP-mTn co-localized with rhodamine-phalloidin in permeabilized tobacco BY-2 suspension cells, showing that the fusion protein can specifically label the plant actin cytoskeleton. Constitutive expression of GFP-mTn in transgenic Arabidopsis thaliana plants visualized actin filaments in all examined tissues with no apparent effects on plant morphology or development at any stage during the life cycle. This demonstrates that in a number of different cell types GFP-mTn can serve as a non-invasive marker for the actin cytoskeleton. Confocal imaging of GFP-mTn labeled actin filaments was employed to reveal novel information on the in vivo organization of the actin cytoskeleton in transiently transformed, normally elongating tobacco pollen tubes.

Actins↗
PubMed2000

Light-induced nuclear import of phytochrome-A:GFP fusion proteins is differentially regulated in transgenic tobacco and Arabidopsis.

Phytochromes (phy) are a family of photoreceptors that control various aspects of light-dependent plant development. Phytochrome A (phyA) is responsible for the very low fluence response (VLFR) under inductive light conditions and for the high irradiance response (HIR) under continuous far-red light. We have recently shown that nuclear import of rice phyA:GFP is regulated by VLFR in transgenic tobacco. The import is preceded by very fast, light-induced formation of sequestered areas of phyA:GFP in the cytosol. Here we report that expression of the Arabidopsis phyA:GFP fusion protein in phyA-deficient Arabidopsis plants complements the mutant phenotype. In these transgenic Arabidopsis lines, both light-dependent cytosolic formation of sequestered areas of the phyA:GFP as well as VLFR or HIR-mediated nuclear import of the fusion protein was observed. By contrast, light-dependent nuclear import of the same fusion protein was induced only by continuous far-red light (HIR) but not by pulses of far-red light (VLFR) in transgenic tobacco. These results demonstrate that photoregulation of intracellular partitioning of the Arabidopsis phyA:GFP differs significantly in different genetic backgrounds.

Arabidopsis↗
PubMed2003

GFP-tagging of cell components reveals the dynamics of subcellular re-organization in response to infection of Arabidopsis by oomycete pathogens.

Cytoplasmic aggregation, the rapid translocation of cytoplasm and subcellular components to the site of pathogen penetration, is one of the earliest reactions of plant cells against attack by microorganisms. We have investigated cytoplasmic aggregation during Arabidopsis-oomycete interactions. Infection by non-pathogenic Phytophthora sojae was prevented in the plant epidermal cell layer, whereas Peronospora parasitica isolates Cala2 (avirulent) and Noks1 (virulent) could both penetrate into the mesophyll cell layer. Epidermal cell responses to penetration by these oomycetes were examined cytologically with a range of transgenic Arabidopsis plants expressing Green Fluorescent Protein (GFP)-tagged cell components. These included plants containing GFP-TUA6 for visualizing microtubules, GFP-hTalin for actin microfilaments, GFP-tm-KKXX for endoplasmic reticulum (ER), and STtmd-GFP for the Golgi apparatus. In all interactions, actin microfilaments were actively re-arranged and formed large bundles in cytoplasmic strands focused on the penetration site. Aggregation of ER membrane and accumulation of Golgi bodies at the infection site were observed, suggesting that production and secretion of plant materials were activated around the penetration site. Microtubules did not become focused on the penetration site. No difference was evident between the responses of epidermal cells in the non-host, incompatible and compatible interactions. This result indicates that the induction of cytoplasmic aggregation in Arabidopsis epidermal cells was neither suppressed by the virulent strain of Peronospora, nor effective in stopping infection.

Actin Cytoskeleton↗
PubMed2001

Distribution of an NMDA receptor:GFP fusion protein in sensory neurons is altered by a C-terminal construct.

The NMDA receptor plays an important role in mediating sensory input to the spinal cord. Domains within the C-terminus of the NMDA receptor bind to cytoskeletal proteins and facilitate membrane targeting and synaptic clustering, and may participate in regulation of receptor function. One strategy to manipulate NMDA receptor function is to express C-terminal constructs in neurons to disrupt synaptic clustering via competition for binding motifs in cytoskeletal proteins and postsynaptic densities. Biolistic particle-mediated gene transfer was used to deliver plasmid DNA into organotypic cultures of dorsal root ganglia (DRG). Fusion proteins consisting of recombinant (r)NMDA receptor subunit 1-1 (rNR1-1) deletion constructs and enhanced green fluorescent protein (GFP) were expressed in sensory neurons and demonstrated unique distribution patterns within the cell. Expression of the full length rNR1-1:GFP construct was cytosolic and localized to membranous patches similar to endogenous NR1-1 protein expression in sensory neurons. Expression of a construct containing only the C-terminus, GFP:C0C1C2, demonstrated nuclear and membranous localization. When the GFP:C0C1C2 construct was co-expressed with rNR1-1 in sensory neurons, membranous localization of rNR1-1 was disrupted. In contrast, co-expression of a C-terminal cassette lacking the C1 exon cassette, GFP:C0C2, with rNR1-1 did not alter the membranous distribution of rNR1-1. This observation verifies the utility of a gene transfer strategy to diminish membranous NR1-1 content by expressing a construct containing the C1 exon cassette.

Active Transport, Cell Nucleus↗
PubMed2005

Cell-to-cell movement of GFP during embryogenesis and early seedling development in Arabidopsis.

There is increasing evidence for intercellular trafficking of macromolecules through plasmodesmata (PD) during plant development. Here we study the ability of PD to traffic proteins during embryogenesis and early seedling development in Arabidopsis. Transgenic lines that induce GFP expression only in meristems, MSG (meristem-specific GFP), were used to monitor GFP movement. Cell-to-cell movement of different-sized GFP reporters reveals that embryos and young seedlings traffic proteins at least 54 kDa in size. Although 27-kDa soluble GFP (1 x sGFP) freely moves between cells throughout the entire embryo during all stages analyzed, 2 x sGFP movement becomes more restricted as development proceeds. After germination, cells near the apical meristem in seedlings show a higher size exclusion limit (SEL), whereas the SEL becomes more restricted as surrounding tissues develop identities. Although 1 x sGFP moves throughout leaf primordia, as the leaf develops only the basal part of leaf petioles, main vascular tissues, and leaf veins (not blades) allow 1 x sGFP movement. Although previous studies showed that embryos allow movement of small symplastic tracers (0.5 kDa), the present data demonstrate that the embryo constitutes a single symplast that allows transport of macromolecules as well. Even 2 x sGFP moves from its site of expression at the apical meristem in embryos and seedlings, yet the extent of movement is more limited than 1 x sGFP. Thus, PD have distinct SELs in different subregions of the embryo and seedling. These studies support the general concept that PD in younger tissues are more dilated and less restrictive than PD in older (nonvascular) tissues.

Arabidopsis↗
PubMed2001

A protein trap strategy to detect GFP-tagged proteins expressed from their endogenous loci in Drosophila.

In Drosophila, enhancer trap strategies allow rapid access to expression patterns, molecular data, and mutations in trapped genes. However, they do not give any information at the protein level, e.g., about the protein subcellular localization. Using the green fluorescent protein (GFP) as a mobile artificial exon carried by a transposable P-element, we have developed a protein trap system. We screened for individual flies, in which GFP tags full-length endogenous proteins expressed from their endogenous locus, allowing us to observe their cellular and subcellular distribution. GFP fusions are targeted to virtually any compartment of the cell. In the case of insertions in previously known genes, we observe that the subcellular localization of the fusion protein corresponds to the described distribution of the endogenous protein. The artificial GFP exon does not disturb upstream and downstream splicing events. Many insertions correspond to genes not predicted by the Drosophila Genome Project. Our results show the feasibility of a protein trap in Drosophila. GFP reveals in real time the dynamics of protein's distribution in the whole, live organism and provides useful markers for a number of cellular structures and compartments.

Animals↗
PubMed2003

Biweekly low-dose sequential gemcitabine, 5-fluorouracil, leucovorin, and cisplatin (GFP): a highly active novel therapy for metastatic adenocarcinoma of the exocrine pancreas.

Phase II studies have suggested an improved response rate and acceptable toxicity profile associated with gemcitabine combinations compared to gemcitabine alone for treatment of metastatic adenocarcinoma of the pancreas. The GFP regimen (gemcitabine, 5-fluorouracil, leucovorin, and cisplatin) is based on laboratory evidence of disease-specific chemotherapy interaction. This retrospective analysis examined the outcome of 49 consecutive patients with histologically confirmed metastatic pancreatic adenocarcinoma treated between July 1998 and September 2000. Day 1 treatment consisted of gemcitabine 500 mg/m2 over 30 minutes and then leucovorin 300 mg bolus, 5-fluorouracil (5-FU) 400 mg/m2 bolus, followed by infusional 5-FU 600 mg/m2 over 8 hours. Day 2 consisted of leucovorin 300 mg bolus, 5-FU 400 mg/m2 bolus, followed by cisplatin 50-75 mg/m2 over 30 minutes and then infusional 5-FU 600 mg/m2 over 8 hours. Treatment was administered every 2 weeks. Median patient age was 61.5 years, 74% were men, and 20 patients had refractory disease (11 patients had disease progression upon gemcitabine-based therapy). Grade 3-4 toxic effects (% patients) consisted of neutropenia (30%), thrombocytopenia (14%), anemia (8%), and neutropenic fever (2%). Grade 3-4 nonhematological toxicities (% patients) consisted of neuropathy (14%), ototoxicity (8%), nephrotoxicity (6%), nausea/vomiting (14%), and mucositis (10%). The majority of dose reductions were made for neuropathy or cytopenias. Filgrastim and erythropoietin were given as needed to promote dose intensity. Eight patients attained a partial response (PR) by RECIST criteria. Fourteen had stable disease (SD). Two patients attaining PR and two attaining SD had progressive disease with prior gemcitabine-based therapy. The median time to disease progression (TTP) from GFP start was 9 weeks. For all 49 patients, the median overall survival (OS) from GFP start was 10.6 months, 12-month survival was 46%, and 24-month survival was 30%. Notably, upon disease progression, 31 patients continued to receive the GFP regimen with irinotecan 80 mg/m2 inserted on day 1 following gemcitabine, the G-FLIP regimen (gemcitabine, 5-fluorouracil, leucovorin, irinotecan, and cisplatin). Measured from G-FLIP initiation, the TTP for the 31 patients treated sequentially was 10 weeks, and for the 14 patients attaining SD or PR the TTP was 25 weeks. The median overall survival measured from GFP initiation was 11.8 months. The response rate, non-cross resistance, TTP, OS, and tolerability warrant prospective development of this novel combination. This experience also demonstrates that adding a single new drug such as irinotecan to the same first-line chemotherapy combination upon disease progression may be an important alternative for the treatment of relapsed/resistant cancer.

Adenocarcinoma↗