Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0598934 (tumor growth)
 58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to increase the selective localization of anti-cancer drugs to the target tumor cells, polyclonal or monoclonal anti alpha-fetoprotein antibody (aAFP) was conjugated with anti-cancer drugs such as daunomycin (DM), adriamycin (AM) and mitomycin C (MMC) by chemical modification. Dextran (Dex) or poly L-glutamic acid (PLGA) was used to bind aAFP with DM (AM) as an intermediate drug carrier. For the conjugation of aAFP with MMC, a direct binding method through the aziridine ring of the activated MMC derivative or an indirect binding method through serum albumin as an intermediate drug carrier was employed. These conjugates caused greater inhibition of both in vitro and in vivo tumor growth of AFP-producing target tumor cells than did a mixture of aAFP and anti-cancer drugs or a simular conjugate of these drugs with normal horse immunoglobulin. AFP has high affinity to unsaturated fatty acids (UFA) such as arachidonic acid (C20:4) and so on. The antitumor effect of UFA-DM conjugate was also assessed using AFP-producing rat ascites hepatoma cells. It was found that UFA-DM conjugated showed highly selective cytocidal effects against the hepatoma cells.
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PMID:[Chemical modification of anti-cancer drugs to increase their affinity to tumor antigens]. 258 Apr 85

Previous studies from this laboratory have demonstrated that growth of the methylcholanthrene (MCA) sarcoma is dependent on total nitrogen substrate availability in vivo and on the specific amino acids asparagine and glutamine in vitro. This experiment determines whether these two phenomena can be used to selectively depress tumor growth and maintain host carcass. Sixty-two rats were inoculated with sarcoma and were infused for 10 days with isocaloric (60 kcal/day) TPN solutions at 100%, 16%, 10%, and 5% of normal nitrogen levels, either with (W) or isonitrogenously without (WO) the amino acids asparagine, glutamine, aspartic acid, and glutamic acid. W solutions contained 33% of these amino acids. Mean weights of 100 W tumors were significantly greater (p = 0.002) than all other groups. Total body weights minus tumor weights were similar in W versus WO animals at each rate of nitrogen infusion. Mean venous plasma concentrations of asparagine, aspartic acid, glutamine, and glutamic acid were similar in all eight groups. These data indicate that the same degree of tumor depression produced by nitrogen deprivation can also be produced by removal of asparagine, glutamine, and their precursors from nutrient solutions without adverse effects on carcass mass. The mechanisms involved are not readily explained by analysis of venous plasma amino acid concentrations.
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PMID:Influence of total nitrogen, asparagine, and glutamine on MCA tumor growth in the Fischer 344 rat. 289 15

Analogues of classical antifolates with the 4-aminobenzoyl group replaced by 4-amino-1-naphthoyl were synthesized for study after molecular modeling indicated ample spatial accommodation for the naphthalene ring and even larger groups in models based on reported X-ray crystallographic data describing the binding of methotrexate to human dihydrofolate reductase (DHFR). The side-chain precursors, N-(4-amino- and 4-(methylamino)-1-naphthoyl)-L-glutamic acid diethyl esters, were synthesized, and the 2,4-diamino-substituted heterocyclic groups were attached using several methods. Target compounds included naphthoyl analogues of aminopterin (AMT), methotrexate (MTX), 5-deazaAMT, 5-deazaMTX, 5-methyl-5-deazaAMT, 5-methyl-5-deazaMTX, and 5,8-dideazaAMT. A 5,6,7,8-tetrahydronaphthoyl analogue of 5-deazaAMT was also prepared. None of the naphthoyl analogues showed loss in binding to DHFR compared with the corresponding antifolate bearing the benzoyl group, thus confirming the anticipated bulk tolerance. Only the 5,6,7,8-tetrahydronaphthoyl analogue displayed reduced antifolate effects. Substrate activity toward folylpolyglutamate synthetase was, however, severely compromised. The naphthoyl compounds were transported into L1210 cells 3-6 times more readily than MTX, and despite apparently low levels of intracellular polyglutamylation, each compound was found to be significantly more potent than MTX in inhibiting tumor cell growth in vitro in three lines (L1210, HL60, and S180). The MTX, 5-methyl-5-deazaAMT, and 5-methyl-5-deazaMTX analogues were evaluated in vivo alongside MTX against E0771 mammary adenocarcinoma in mice. All three proved more effective than MTX in retarding the tumor growth. The naphthoyl analogue of 5-deazaAMT strongly inhibited DHFR from Pneumocystis carinii, Toxoplasma gondii, and rat liver giving IC50 (pM) values of 0.53, 2.1, and 1.6 respectively, but this compound did not inhibit in vitro growth of T. gondii, thus indicating lack of transport.
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PMID:Studies on analogues of classical antifolates bearing the naphthoyl group in place of benzoyl in the side chain. 827 97

ZD2767 represents an improved version of antibody-directed enzyme prodrug therapy. It consists of a conjugate of the F(ab')2 A5B7 antibody fragment and carboxypeptidase G2 (CPG2) and a prodrug, 4-[N,N-bis(2-iodoethyl)amino]phenoxycarbonyl L-glutamic acid. The IC50 of the prodrug against LoVo colorectal tumor cells was 47 microM, and cleavage by CPG2 released the potent bis-iodo phenol mustard drug (IC50 = 0.34 microM). The drug killed both proliferating and quiescent LoVo cells. Administration of the ZD2767 conjugate to nude mice bearing LoVo colorectal xenografts resulted in approximately 1% of injected ZD2767 conjugate localizing/g of tumor after 72 h, and blood and normal tissue levels of the conjugate were 10-50-fold lower. A single round of therapy involving the administration of the prodrug 72 h after the conjugate to athymic mice bearing established LoVo xenografts resulted in approximately 50% of the tumors undergoing complete regressions, tumor growth delays greater than 30 days, and little toxicity (as judged by body-weight loss). Similar studies using a control antibody-CPG2 conjugate that does not bind to LoVo tumor cells resulted in a growth delay of less than 5 days, confirming the tumor specificity of this approach. These studies demonstrate the potential of ZD2767 for the treatment of colorectal cancer.
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PMID:ZD2767, an improved system for antibody-directed enzyme prodrug therapy that results in tumor regressions in colorectal tumor xenografts. 876 23

The water-soluble conjugates of mitomycin C (MMC) with N-succinyl-chitosan (N-Suc-chitosan) and glycol-chitosan (Gly-chitosan), named N-Suc-chitosan-glu-MMC and Gly-chitosan-glu-MMC, respectively, were characterized mainly by the plasma concentration-time profiles of MMC after intraperitoneal administration and their in vivo antitumor effect against P388 leukemia and Sarcoma 180. Before in vivo evaluation, polymer-drug binding characteristics were checked by gel-chromatography. Gel-chromatographs proposed the covalent binding of 1a-(4-carboxybutyryl)-MMC (glu-MMC) with both the polymer supports. The plasma concentration of MMC showed that each conjugate released MMC in vivo at a similar rate. Kinetic analysis suggested that the in vivo drug release should be considerably faster than the in vitro release in the buffer, pH 7.4, alone. In the treatment against P388 leukemia inoculated intraperitoneally, Gly-chitosan-glu-MMC showed the highest increase in life span (ILS) at 10 mg MMC eq/kg. It was lethally toxic at the dose of 20 mg MMC eq/kg, while N-Suc-chitosan-glu-MMC gave the highest ILS value at this dose. Each conjugate exhibited a little larger ILS value than MMC. For the Sarcoma 180 solid tumor inoculated subcutaneously, the polymer characteristics affected the antitumor effect. Namely, with the intravenous injection, Gly-chitosan-glu-MMC hardly exhibited any tumor growth inhibition, but N-Suc-chitosan-glu-MMC showed significant tumor growth suppression. As to the intratumoral administration, the tendency to suppress tumor growth was observed in MMC and both the conjugates.
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PMID:In vivo drug release and antitumor characteristics of water-soluble conjugates of mitomycin C with glycol-chitosan and N-succinyl-chitosan. 888 36

Angiogenesis is essential for tumor growth and metastasis. Here, we have developed a peptide antagonist of human angiogenin, which is a potent and tumor-associated angiogenic factor. ANI-E peptide was derived from the phage clone, which binds to angiogenin via the disulfide-constrained octapeptide epitope that is displayed on its surface, and is displaced by actin. Disulfide-constrained ANI-E peptide inhibits the interaction of angiogenin with actin, which is regarded as the angiogenin-binding protein on the surface of endothelial cells, without any visible effect on the ribonucleolytic activity of angiogenin. The peptide also inhibits the neovascularization that is induced by angiogenin in the chick chorioallantoic membrane assay. The antiangiogenic activity of the peptide is specific for angiogenin because the peptide does not have any apparent effect on embryonic angiogenesis or the preexisting blood vessels. The disulfide bond and the glutamic acid inside the disulfide ring of ANI-E peptide are indispensable for its antiangiogenin activity. Furthermore, ANI-E peptide blocks the angiogenesis that is induced by the angiogenin-secreting PC3 human prostate adenocarcinoma cells, without any direct effect on the proliferation, as well as the adhesion of PC3 cells to angiogenin. Therefore, the inhibition of the tumor-induced angiogenesis by ANI-E peptide is most likely caused by the neutralization of the extracellular angiogenin that is secreted by PC3 cells. On the basis of our results, ANI-E peptide may be effective for the treatment of various human tumors that secrete angiogenin. Our results also strongly support the hypothesis that the interaction of angiogenin with the cell surface actin-like protein is essential for the biological action of angiogenin, and angiogenin has an essential role in tumor-induced angiogenesis.
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PMID:Development of antiangiogenin peptide using a phage-displayed peptide library. 928 81

The irregular nature of solid tumor vasculature produces a heterogeneous distribution of antibody-targeted therapies within the tumor mass, which frequently results in reduced therapeutic efficacy. We have, therefore, combined two complementary therapies: Antibody-directed Enzyme Prodrug Therapy (ADEPT), which targets tumor cells, and an agent that selectively destroys tumor vasculature. A single i.p. dose (27.5 mg/kg) of the drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA), given to nude mice bearing the LS174T colorectal xenograft, destroyed all but a peripheral rim of tumor cells, without enhancing survival. The ADEPT system, in which a pretargeted enzyme activates a prodrug, consisted of the F(ab')2 fragment of anti-carcinoembryonic antigen antibody A5B7 conjugated to the bacterial enzyme carboxypeptidase G2 and the prodrug 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-L-glutamic acid, which was given i.p. in three doses of 500 mg/kg at 72, 84, and 96 h post-conjugate administration (25 units of carboxypeptidase G2). The antibody-enzyme conjugate could be selectively retained at approximately twice the control levels by administration of the antivascular agent at the time of optimal conjugate localization within the tumor (20 h post-conjugate administration), as demonstrated by gamma counting, phosphor plate image analysis, and active enzyme measurement. This resulted in significantly enhanced tumor growth inhibition in groups of six mice, compared to conventional ADEPT therapy, with no concomitant increase in systemic toxicity. In a separate experiment, aimed at trapping the prodrug within the tumor, a 16-fold increase over control values was produced (means, 44.8 versus 2.8 microg/g tumor) when DMXAA was given 4 h prior to 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-L-glutamic acid. The therapeutic window was small, with no significant enhancement of prodrug retention when DMXAA was given at either earlier or later time points. This correlated with the time of vascular shut-down induced by the antivascular agent. We are currently investigating whether it is more advantageous to trap increased levels of conjugate or prodrug within the tumor for maximal enhancement of conventional ADEPT. These studies demonstrate that combined use of antibody-directed and antivascular therapies can significantly benefit the therapeutic outcome of either strategy alone.
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PMID:Enhancement of antibody-directed enzyme prodrug therapy in colorectal xenografts by an antivascular agent. 1046 98

Ras proteins are small GTPases playing a pivotal role in cell proliferation and differentiation. Their activation state depends on the competing action of GTPase Activating Proteins (GAP) and Guanine nucleotide Exchange Factors (GEF). A tryptophan residue (Trp1056 in CDC25Mm-GEF), conserved in all ras-specific GEFs identified so far has been previously shown to be essential for GEF activity. Its substitution with glutamic acid results in a catalytically inactive mutant, which is able to efficiently displace wild-type GEF from p21ras and to originate a stable ras/GEF binary complex due to the reduced affinity of the nucleotide-free ras/GEF complex for the incoming nucleotide. We show here that this 'ras-sequestering property' can be utilized to attenuate ras signal transduction pathways in mouse fibroblasts transformed by oncogenic ras. In fact overexpression of the dominant negative GEFW1056E in stable transfected cells strongly reduces intracellular ras-GTP levels in k-ras transformed fibroblasts. Accordingly, the transfected fibroblasts revert to wild-type phenotype on the basis of morphology, cell cycle and anchorage independent growth. The reversion of the transformed phenotype is accompanied by DNA endoreduplication. The possible use of dominant negative ras-specific GEFs as a tool to down-regulate tumor growth is discussed.
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PMID:A dominant negative RAS-specific guanine nucleotide exchange factor reverses neoplastic phenotype in K-ras transformed mouse fibroblasts. 1081 6

The poly(L-glutamic acid)-paclitaxel (PG-TXL) conjugate has been shown to exhibit significantly greater antitumor activity than conventionally formulated paclitaxel (TXL) against solid tumors (Li et al., Cancer Res., 58: 2404-2409, 1998). Here we report that local tumor irradiation enhanced the distribution of PG-TXL given 24 h later to ovarian OCa-1 carcinoma implanted i.m. in C3Hf/Kam mice. Radiation significantly increased tumor uptake of PG-TXL and tumor vascular permeability, caused elevation of the serum concentration of vascular endothelial growth factor, and arrested OCa-1 cells in the G1 phase of cell cycle. The enhancement factors, as measured by incremental tumor growth delay compared with PG-TXL alone, ranged from 1.36-4.44. Complete tumor regression was also observed at a higher radiation dose (>10 Gy) and a higher PG-TXL dose (>80 mg equivalentTXL/kg). Furthermore, combined radiation and PG-TXL produced a significantly greater tumor growth delay than treatment with radiation and TXL when both drugs were given at the same equivalent TXL dose of 60 mg/kg 24 h after tumor irradiation (enhancement factors, 4.44 versus 1.50). These data suggest that conjugation of TXL to poly(L-glutamic acid) is necessary for improved response and that the supra-additive effect of combined radiation and PG-TXL therapy is due in part to modulation of the enhanced permeability and retention effect of macromolecules by radiation. We propose a treatment strategy combining radiation and macromolecular chemotherapy that may have important clinical implications in terms of scheduling and optimization of the therapeutic ratio.
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PMID:Tumor irradiation enhances the tumor-specific distribution of poly(L-glutamic acid)-conjugated paclitaxel and its antitumor efficacy. 1091 31

Although combined chemotherapy and radiotherapy has produced significantly improved response and survival rates among cancer patients, there is still a compelling need to establish the most effective way to deliver these agents. We hypothesize that the radiosensitizing effect of a chemotherapeutic agent can be further enhanced if the drug is delivered at an optimal concentration and is maintained in the tumor for a prolonged period. Using a water-soluble poly(L-glutamic acid)-conjugated paclitaxel (PG-TXL) as a model compound, we investigated whether paclitaxel delivered by means of polymeric carrier could increase the tumor's response to radiation. Mice bearing 8-mm syngeneic ovarian carcinoma OCa-1 tumors implanted intramuscularly were treated with i.v. injected PG-TXL alone or in combination with single doses of local radiation. The enhancement factors at 24 h interval, as measured by incremental tumor growth delay compared with radiation alone, ranged from 2.48 to 4.28. The values varied as a function of radiation dose. The enhancement of radioresponse is also a function of time interval between injection of PG-TXL and tumor irradiation. The enhancement factor increased with decreasing interval, suggesting that radiation may in turn mediate the sensitivity of tumor toward PG-TXL. Thus, the mechanism of PG-TXL's radiopotentiation activity is probably multifactorial. Remarkably, while combined radiation and TXL produced additive or even sub-additive interaction when radiation preceded TXL injection, combined radiation and PG-TXL produced synergistic interaction in a mammary MCa-4 tumor model. Radiation significantly increased tumor uptake of PG-TXL, suggesting a potential role of radiation-modulated antitumor activity of polymeric drugs. Our data support a treatment strategy combining radiation and polymeric chemotherapy that may have important clinical implications in terms of scheduling and optimization of the therapeutic ratio.
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PMID:Potentiation of radioresponse by polymer-drug conjugates. 1148


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