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At least 559 records · Page 31Linked to original sources
PubMed2002

Identification of FGF receptor-binding peptides for cancer gene therapy.

Linear FGF receptor-binding heptapeptides were identified by phage display using sequential rounds of biopanning against cells with displacement of phage by FGF2. The consensus motif MXXP was iterated after four to five rounds and the peptide MQLPLAT was studied in depth. Phage bearing MQLPLAT showed high levels of binding to FGF receptor positive cells, with over 90% of phage bound being eluted competitively by adding free FGF2. MQLPLAT phage showed only limited binding to Cos7 cells deficient in receptors for FGF. MQLPLAT phage bound to SKOV3 cells with a K(d) of 2.51 x 10(-10) M. Although binding could be blocked by preincubation with free FGF2, heparin could not displace the phage. Use of MQLPLAT to target polyelectrolyte gene delivery vectors in vitro in the presence of serum achieved up to 40-fold greater transgene transduction than nontargeted vectors. MQLPLAT phage were administered into gastric carcinomas via the tumor-feeding artery immediately following resection from patients. The phage showed up to 9-fold more accumulation in the tumor than in adjacent regions of normal tissue, whereas control phage showed less than 2-fold. These peptides should provide useful ligands for specific delivery of gene therapy vectors to clinically relevant targets.

Amino Acid Motifs↗
PubMed2005

A multiprong approach to cancer gene therapy by coencapsulated cells.

Immune-isolation of nonautologous cells with microencapsulation protects these cells from graft rejection, thus allowing the same recombinant therapeutic cell line to be implanted in different recipients. This approach was successful in treating HER2/neu-expressing tumors in mice by delivering an interleukin-2 fusion protein (sFvIL-2), or angiostatin. However, treatment with interleukin-2 led to profuse inflammation, while angiostatin delivery did not result in long-term tumor suppression, in part due to endothelial cell-independent neovascularization (vascular mimicry). We hypothesize that coencapsulating the two producer cells in the same microcapsules may enhance the efficacy and ameliorate the above side effects. Hence, B16-F0/neu tumor-bearing mice were implanted with sFvIL-2- and angiostatin-secreting cells coencapsulated in the same alginate-poly-L-lysine-alginate microcapsules. However, this protocol only produced an incremental but not synergistic improvement, as measured with greater tumor suppression and improved survival. Compared to the single sFvIL-2 treatment, the coencapsulation protocol showed improved efficacy associated with: mobilization of sFvIL-2 from the spleen; a higher level of cytokine delivery systemically and to the tumors; increased tumor and tumor-associated endothelial cell apoptosis; and a reduced host inflammatory response. However, compared to the single angiostatin treatment, the efficacy was reduced, primarily due to a "bystander" effect in which the angiostatin-secreting cells suffered similar transgene silencing as the coencapsulated cytokine-secreting cells. Nevertheless, the level of "vascular mimicry" of the single angiostatin treatment was significantly reduced. Hence, while there was no synergy in efficacy, an incremental improvement and some reduction in undesirable side effects of inflammation and vascular mimicry were achieved over the single treatments.

Alginates↗
PubMed1999

Cancer gene therapy using a pro-apoptotic gene, caspase-3.

Caspase-3 is a member of the cysteine protease family, which plays a crucial role in apoptosis. We applied the human caspase-3 gene as a novel form of anticancer gene therapy. Overexpression of human caspase-3 alone could not induce apoptosis of tumor cell lines, but apoptosis was markedly enhanced by the addition of etoposide. In an AH130 liver tumor model, transduction of human caspase- 3, but not the empty vector, induced extensive apoptosis and reduced tumor volume when combined with etoposide administration. However, this effect was not observed with a Bcl-2 overexpressing tumor. In conclusion, caspase-3 gene transduction accompanied by an additional death stimulus may be a useful method of anticancer gene therapy, except for Bcl-2 overexpressing tumors.

Adenoviridae↗
PubMed2000

Efficacy of cancer gene therapy in aging: adenocarcinoma cells engineered to release IL-2 are rejected but do not induce tumor specific immune memory in old mice.

Numerous studies have demonstrated the efficacy of cytokine gene-engineered tumor cells to induce tumor rejection and specific memory acquisition into syngeneic immunocompetent mice by activation of host-dependent antitumor responses. A progressive immune dysfunction, mainly involving thymus-dependent specific immunity, occurs during aging. In this study we evaluated whether the injection of IL-2 gene-transfected tumor cells in old mice causes an immune activation which results in tumor rejection and induction of specific immune memory as occurs in young animals. Young and old mice were inoculated with syngeneic parental mammary adenocarcinoma cells (TS/A p.c.) or with TS/A cells engineered to release IL-2 (TS/A-IL2). Three clones of TS/A-IL-2 cells were used producing low (30 U, B1.30), intermediate (3600 U, B6.3600), or high (6000 U, B4.6000) IL-2. While the B1.30 clone grew in 100% of mice, the B6.3600 and B4.6000 clones were promptly rejected in both young and old animals. In young mice, rejection was associated with a large neutrophil and macrophage infiltration, with a minor number of CD4+ and CD8+ lymphocytes. In old mice, neutrophils and macrophages were the main cells involved in tumor rejection whereas both CD4+ and CD8+ lymphocytes were scarcely present in tumoral infiltrate. A lower number of apoptotic tumor cells was found in TS/A-IL2-challenged old mice in comparison with young animals. To test whether the injection of TS/A-IL2 cells induced a specific immune memory, mice with no tumors after the challenge with B6.3600 and B4.6000 clones received a lethal challenge of TS/A p.c. 90% and 30% of young mice previously injected with B4.6000 or B6.3600 clones, respectively, rejected TS/A p.c. In old mice, B4.6000 cells did not confer protection, whereas only 10% of mice which received B6.3600 cells were able to reject TS/A p.c. Neither the graft of a young thymus or the adoptive transfer of young T lymphocytes to old mice induced specific immune memory for TS/A p.c. in old animals. These data suggest the necessity to refine antitumor vaccination procedures in aging.

Adenocarcinoma↗
PubMed2005

Growth suppression induced by the TRC8 hereditary kidney cancer gene is dependent upon JAB1/CSN5.

TRC8 encodes an E3-ubiquitin ligase disrupted in a family with hereditary renal cell carcinoma (RCC). We previously reported that Drosophila Trc8 (DTrc8) overexpression inhibits growth and that human and fly proteins interact with with the COP9 signalosome (CSN) subunit JAB1/CSN5. However, further mechanistic evidence linking DTrc8 growth suppression to CSN5 was lacking. Here, we show that haploinsufficiency of CSN5, or a T100I point mutation (CSN5(3)), relieved growth suppression by DTrc8, whereas CSN5(1) (E160V) and CSN5(2) (G147D) mutations had no effect. The strength of yeast two-hybrid interactions between DTrc8 and CSN5 were in complete agreement with the observed phenotypes. DTrc8 overexpression resulted in elevated levels of CSN5 and CSN7, but had no effect on NEDD8-modified Cul-1. In contrast to CSN5, heterozygosity for CSN4null had no effect on the DTrc8 phenotype. We also looked for genetic interactions between DTrc8 and other MPN domain proteins in the CSN and 26S proteasome lid. CSN6 haploinsufficiency restored growth, whereas reduction of proteasome subunits RPN8 or RPN11 had no effect. DTrc8 expression increased the level of digitonin-extractable CSN complex, consistent with elevated levels of CSN5 and 7. Our genetic results confirm that DTrc8-induced growth suppression is CSN5 (and CSN6) dependent. While there was no obvious influence on CSN deneddylation activity, the increase in CSN subunits and holocomplex suggests that TRC8 modulates signalosome levels or compartmentalization.

Adaptor Proteins, Signal Transducing↗
PubMed2006

RING-dependent tumor suppression and G2/M arrest induced by the TRC8 hereditary kidney cancer gene.

TRC8/RNF139 and von Hippel-Lindau (VHL) both encode E3 ubiquitin (Ub) ligases mutated in clear-cell renal carcinomas (ccRCC). VHL, inactivated in nearly 70% of ccRCCs, is a tumor suppressor encoding the targeting subunit for a Ub ligase complex that downregulates hypoxia-inducible factor-alpha. TRC8/RNF139 is a putative tumor suppressor containing a sterol-sensing domain and a RING-H2 motif essential for Ub ligase activity. Here we report that human kidney cells are growth inhibited by TRC8. Inhibition is manifested by G2/M arrest, decreased DNA synthesis and increased apoptosis and is dependent upon the Ub ligase activity of the RING domain. Tumor formation in a nude mouse model is inhibited by TRC8 in a RING-dependent manner. Expression of TRC8 represses genes involved in cholesterol and fatty acid biosynthesis that are transcriptionally regulated by the sterol response element binding proteins (SREBPs). Expression of activated SREBP-1a partially restores the growth of TRC8-inhibited cells. These data suggest that TRC8 modulation of SREBP activity comprises a novel regulatory link between growth control and the cholesterol/lipid homeostasis pathway.

Amino Acid Sequence↗
PubMed2001

E. coli nitroreductase/CB1954: in vitro studies into a potential system for feline cancer gene therapy.

Investigations were carried out to identify a suitable prodrug activating system for feline gene therapy with the eventual aim of treating feline thyroid disease and feline neoplasia. The E. coli nitroreductase (NTR)/CB1954 prodrug activating system was evaluated in vitro in feline cells by transient transfection with a nitroreductase expressing construct and subsequent treatment with the prodrug CB1954. The feline cells successfully expressed E. coli nitroreductase, which was able to activate the prodrug CB1954 resulting in cytotoxicity to both transformed and adjacent cells (a bystander effect) in vitro. In the absence of nitroreductase, CB1954 was non-toxic to feline cells. In addition, the nitroreductase gene was expressed in rat thyroid cells under the control of the cell type specific feline thyroglobulin promoter. This paper demonstrates that the E. coli nitroreductase/CB1954 system may be suitable for in vivo feline gene therapy, and further investigations are warranted.

Animals↗
PubMed1996

Converting cancer genes into killer genes.

Over the past decade, it has become clear that tumorigenesis is driven by alterations in genes that control cell growth or cell death. Theoretically, the proteins encoded by these genes provide excellent targets for new therapeutic agents. Here, we describe a gene therapy approach to specifically kill tumor cells expressing such oncoproteins. In outline, the target oncoprotein binds to exogenously introduced gene products, resulting in transcriptional activation of a toxic gene. As an example, we show that this approach can be used to specifically kill cells overexpressing a mutant p53 gene in cell culture. The strategy may be generally applicable to neoplastic diseases in which the underlying patterns of genetic alterations or abnormal gene expression are known.

Cell Line↗