Flowering plants used against snakebite

A list of flowering plants used for the treatment of snakebite has been complied from a variety of literature sources. Details of the geographical area and parts used are given and the basis for the reputed activity discussed. Methods of testing the reputed activity of such plants are reviewed and the identity and mode of action of the chemical substances which might be responsible is discussed for some of the plants listed.

Monoclonal antibodies to the myogenic regulatory protein MyoD1: epitope mapping and diagnostic utility

Monoclonal antibodies (MoAbs) were developed against recombinant wild-type murine MyoD1 protein. Each of 4 MoAbs was immunologically reactive with recombinant MyoD1 protein by enzyme-linked immunosorbent assay, and each specifically stained the nuclei of myogenic cells. Epitopes were mapped using fusion protein constructs with specific deletions of defined regions of the MyoD1 molecule. MoAb 5.2F recognized an epitope in the amino terminal region between amino acid residues (AAR) 3 and 56, whereas epitopes for MoAbs 1.1A, 5.4G, and 5.8A were in the carboxyl terminus (AAR 167-318) of the MyoD1 protein. The epitope for MoAb 5.8A was further delineated to AAR 170-209 by Western analysis and immunoprecipitation of in vivo transcribed and translated MyoD1 protein having specific deletions in the carboxyl terminus. The 5.8A epitope was ultimately localized to the region between AAR 180 and 189 of the protein by enzyme-linked immunosorbent assay using 10-amino acid residue synthetic peptides. This sequence is apparently unique to MyoD1 and has little homology to other myogenic regulatory proteins (myogenin, Myf5, Myf6, and MRF4). Transfection of cDNA for murine MyoD1 into a nonmuscle cell line conferred 5.8A reactivity, confirming the specificity of this reagent. MoAb 5.8A was then used to examine the expression of MyoD1 in normal and malignant human tissues. MyoD1 was not detected in any normal adult tissue but was detected in 25 of 25 histologically confirmed rhabdomyosarcomas. Staining was localized to the nucleus and showed marked heterogeneity between cells as well as differential staining within nuclei. Specific subcellular localization of 5.8A was further determined by immunoelectron microscopy, where antibody was found to localize to electron-dense areas, more frequently associated with the nuclear submembranous region. In addition to rhabdomyosarcomas, MoAb 5.8A stained 2 of 5 Wilms' tumors and one ectomesenchymoma, neoplasms known to contain myogenic elements. The 5.8A reagent was also of value in the accurate histopathological classification of 2 of 4 tumors previously diagnosed as extraosseous Ewing's sarcoma and 2 of 3 tumors diagnosed as undifferentiated sarcomas.

Synthesis and chemical characterization of N-substituted phenoxazines directed toward reversing vinca alkaloid resistance in multidrug-resistant cancer cells

A series of 21 N-substituted phenoxazines has been synthesized in an effort to find more specific and less toxic modulators of multidrug resistance (MDR) in cancer chemotherapy. Thus, N-(omega-chloroalkyl)- and N-(chloroacyl)phenoxazines were found to undergo iodide-catalyzed nucleophilic substitution on reaction with various secondary amines, including N,N-diethylamine, N,N-diethanolamine, morpholine, piperidine, pyrrolidine and (beta-hydroxyethyl)piperazine. Products were characterized by UV, IR, 1H-, and 13C-NMR, mass spectral data, and elemental analyses. All of the compounds were examined for cytotoxicity and for their ability to increase the accumulation of the vinca alkaloids, vincristine (VCR) and vinblastine (VLB) in multidrug-resistant GC3/Cl (human colon adenocarcinoma) and KBChR-8-5 (HeLa variant) cell lines. Compounds were compared to the standard modulator verapamil (VRP). Substitutions on the phenoxazine ring at position 10 were associated with an increase in antiproliferative and anti-MDR activities. Modification of the length of the alkyl bridge and the type of amino side chain also influenced the potency of these effects. From among the compounds examined, 10 derivatives were found to increase the accumulation of VCR and VLB in GC3/Cl and KBChR-8-5 cells relative to the effect of VRP, suggesting that with the exception of pyrrolidinyl, the tertiary amine attachments to the phenoxazine nucleus linked through a three- or four-carbon alkyl chain resulted in enhanced anti-MDR activity. On the basis of their 50% growth inhibitory (IC50) values, five of the ten compounds, namely, 10-(3'-chloropropyl)phenoxazine, 10-[3'-[N-bis(hydroxyethyl)- amino]propyl]phenoxazine, 10-(3'-N-morpholinopropyl)phenoxazine, 10-(4'-N-morpholinobutyl)phenoxazine and 10-(N-piperidinoacetyl)phenoxazine were selected as relatively nontoxic chemosensitizers. These modulators, at nontoxic concentrations, potentiated the cytotoxicity of VCR and VLB in GC3/Cl and KBChR-8-5 cells. Further, two compounds 10-(3'-N-morpholinopropyl)phenoxazine, and the butyl derivative, enhanced accumulation of VLB in GC3/Cl, KBChR8-5 and highly resistant KB-V1 cells to a level significantly greater than the maximal level achieved with VRP. Additional experiments to understand the mechanism of action of these agents in modulating MDR are in progress.

Absence of tRNA-guanine transglycosylase in a human colon adenocarcinoma cell line

Queuosine (Q), found exclusively in the first position of the anticodons of tRNA(Asp), tRNA(Asn), tRNA(His) and tRNA(Tyr), is synthesized in eucaryotes by a base-for-base exchange of queuine, the base of Q, for guanine at tRNA position 34. This reaction is catalyzed by the enzyme tRNA-guanine transglycosylase (EC 2.4.2.29). We measured the specific release of queuine from Q-5'-phosphate (queuine salvage) and the extent of tRNA Q modification in 6 human tumors carried as xenografts in immune-deprived mice. Q-deficient tRNA was found in 3 of the tumors but it did not correlate with diminished queuine salvage. The low tRNA Q content of one tumor, the HxGC3 colon adenocarcinoma, prompted us to examine a HxGC3-derived cell line, GC3/M. GC3/M completely lacks Q in its tRNA and measurable tRNA-guanine transglycosylase activity; the first example of a higher eucaryotic cell which lacks this enzyme. Exposure of GC3/M cells to 5-azacytidine induces the transient appearance of Q-positive tRNA. This result suggests that at least one allele of the transglycosylase gene in GC3/M cells may have been inactivated by DNA methylation. In clinical samples, we found Q-deficient tRNA in 10 of 46 solid tumors, including 2 of 13 colonic carcinomas.

Mutation(s) of the thymidylate synthase gene of human adenocarcinoma cells causes a thymidylate synthase-negative phenotype that can be attenuated by exogenous folates

Biological characterization of a human colon adenocarcinoma cell line deficient in thymidylate synthase (TS-) is described. The clone, designated TS-C1/C1, was derived from the parental line GC3/C1 by selection in medium containing aminopterin, thymidine (dThd), and low concentrations of 5-formyltetrahydrofolate (5-CHO-H4PteGlu), and was subsequently reselected by single-step cloning in 500 microM methotrexate in the presence of dThd. This clone retained its TS- phenotype, was highly resistant to methotrexate (greater than 100,000-fold), and remained tumorigenic in mice (P.J. Houghton, et al., Proc. Natl. Acad. Sci. USA, 86: 1377-1381, 1989). In studies reported, it is shown that high levels of exogenous folate can support the growth of the TS- C1/C1 clone in the absence of dThd. Activation of dTMP biosynthesis de novo was demonstrated within 6 h of exposing cells to 20 microM [6R,S]5-CHO-H4PteGlu, and greater than or equal to 80% of activity was lost within 24 h of removing this folate from the medium. The labeling index was determined by autoradiographic techniques using [6-3H]2'-deoxyuridine. None of the greater than 6,000 cells radiolabeled in the absence of [6R,S]5-CHO-H4PteGlu, whereas 33.5% labeled in the presence of 20 microM exogenous folate. Relative to the parental (TS+) clone, there was a greater than 87,500-, an 8,182-, and a 425-fold higher requirement for 5-methyltetrahydrofolate ([6R,S]5-CH3-H4PteGlu), PteGlu, and [6R,S]5-CH3-H4PteGlu to support 50% maximal colony formation in the absence of dThd. Quantitative analysis of the combined pools of 5,10-methylenetetrahydrofolate (CH2-H4PteGlun) and H4PteGlun showed that parental GC3/C1 cells had higher endogenous folate pools compared to TS-C1/C1 cells [168 +/- 40 (SD) and 10.9 +/- 0.3 fmol/10(6) cells, respectively]. Qualitatively the distribution of polyglutamate species and their redistribution in cells exposed to 20 microM [6R,S]5-CHO-H4PteGlu were similar in the two lines. Analysis of pools in a second, independently derived, TS- clone (TS-C3/C3, a transcription-negative mutant) demonstrated undetectable levels of CH2-H4PteGlun and H4PteGlun. This line cannot be rescued by exogenous folate. The data thus suggest that deletion of dTMP synthase activity may cause redistribution of reduced folate pools. In cytosolic extracts from parental GC3/C1 (TS+) cells, [6R]CH2-H4PteGlu1 acted as a cofactor in the release of 3H2O from [5-3H]dUMP, whereas no activity was detected in cytosols from TS-C1/C1. In contrast dTMP synthase activity was detected in cytosols from TS- C1/C1 cells in the presence of [6R]CH2-H4PteGlu5.(ABSTRACT TRUNCATED AT 400 WORDS)

Factors that influence the therapeutic activity of 5-fluorouracil [6RS]leucovorin combinations in colon adenocarcinoma xenografts

The therapeutic activity of FUra alone or combined with [6RS]LV doses ranging from 50 to 1,000 mg/m2 was examined in eight colon adenocarcinoma xenografts, of which five were established from adult neoplasms (HxELC2, HxGC3, HxVRC5, HxHC1, and HxGC3/c1TK-c3 selected for TK deficiency) and three were derived from adolescent tumors (HxSJC3A, HxSJC3B, and HxSJC2). The growth-inhibitory effects of FUra were potentiated by higher doses of [6RS]LV (500-1,000 mg/m2) in three lines (HxGC3/c1TK-c3, HxSJC3A, and HxSJC3B) and by a low dose of [6RS]LV in only one tumor (HxVRC5). Expansion of pools of CH2-H4PteGlun+H4PteGlun (greater than or equal to 2.4-fold) in response to higher doses of [6RS]LV was obtained in all lines except HxHC1. Metabolism of [6RS]LV was high in HxVRC5, with high levels of 5-CH3-H4PteGlu being detected, but not in HxHC1, in which levels of 5-CH3-H4PteGlu and CH = H4PteGlu+10-CHO-H4PteGlu remained relatively low. In the adolescent tumors, levels of CH = H4PteGlu+10-CHO-H4PteGlu were consistently higher than those of 5-CH3-H4PteGlu following [6RS]LV administration, and in HxSJC3A, in which pools of CH2-H4PteGlun+H4PteGlun were significantly expanded, 5-CH3-H4PteGlu concentrations were lower than those observed in the other two lines. The sensitivity of tumors to FUra +/- [6RS]LV and the characteristics of [6S]LV metabolism did not correlate with the activity of CH = H4PteGlu synthetase, the enzyme responsible for the initial cellular metabolism of [6S]LV to CH = H4PteGlu. Thus, no single metabolic phenotype correlated with the [6RS]LV-induced expansion of CH2-H4PteGlun+H4PteGlun pools. Potentiation of the therapeutic efficacy of FUra by [6RS]LV was observed in HxGC3/c1TK-c3 xenografts but not in parent HxGC3 tumors, demonstrating the influence of dThd salvage capability in the response to FUra-[6RS]LV combinations. Plasma dThd concentrations in CBA/CaJ mice were high (1.1 microM). The present data therefore demonstrate the importance of (1) higher doses of [6RS]LV, (2) expansion of pools of CH2-H4PteGlun+H4PteGlun, and (3) dThd salvage capability in potentiation of the therapeutic efficacy of FUra in colon adenocarcinoma xenografts. The plasma levels of FUra achieved in mice are presented.

Evaluation of 9-dimethylaminomethyl-10-hydroxycamptothecin against xenografts derived from adult and childhood solid tumors

The topoisomerase I inhibitor 9-dimethylaminomethyl-10-hydroxycamptothecin (topotecan) was evaluated against a panel of xenografts comprising four lines of adult colon adenocarcinoma, three colon tumors derived from adolescents, six childhood rhabdomyosarcomas from previously untreated patients as well as sublines selected in vivo for resistance to vincristine and melphalan, and three lines of childhood osteogenic sarcoma. Efficacy was determined at maximal tolerated dose levels using intermittent i.p. administration [every 4 days for 4 doses (q4dx4)] or daily p.o. or i.p. administration 5 days per week for up to 20 courses. On a q4dx4 schedule, the maximum tolerated dose (MTD) was 12.5 mg/kg per administration, which caused marked weight loss and lethality in approximately 5% of the tumor-bearing mice. This schedule caused significant growth inhibition (but no tumor regression) in advanced adult colon adenocarcinomas. The minimal treated/control (T/C) ratios were 0.49, 0.54, and 0.3 for three of the tumor lines and were achieved at 18-21 days after the initiation of treatment. In contrast, rhabdomyosarcomas were considerably more sensitive, with T/C ratios being < 0.1 for three lines, whereas topotecan was less active against two other rhabdomyosarcoma xenografts (minimal T/C ratios, 0.17 and 0.14). As inhibitors of topoisomerase I have been demonstrated to have activity in the replication phase of the cell cycle (S-phase-specific), prolonged administration schedules were examined. Mice received topotecan 5 days per week for 3 weeks either by i.p. injection or by oral gavage (p.o.). In selected experiments, p.o. administration was continued for up to 20 weeks. Oral administration for 3 weeks (2 mg/kg per dose) resulted in complete regression of all six lines of rhabdomyosarcoma, with two lines demonstrating no regrowth during the period of observation (> or = 84 days). Similar results were obtained after i.p. administration, suggesting significant schedule dependency for these tumors. For colon tumors, the daily administration schedule (i.p. or p.o.) demonstrated some advantage over the intermittent schedule, resulting in partial regressions and significant inhibition of the growth of several colon adenocarcinoma lines. In rhabdomyosarcoma Rh12 and VRC5 colon adenocarcinoma, both of which demonstrated intermediate sensitivity to topotecan, and in osteosarcoma OS33, protracted p.o. administration for 13-20 weeks (1.0-1.5 mg/kg per dose given daily x 5 days) caused complete regression without regrowth in Rh12 and OS33 tumors and partial regression of all VRC5 tumors. No toxicity was observed using this schedule of administration. Topotecan demonstrated significant activity against all three osteosarcoma xenografts examined, with optimal schedules causing complete regression in two lines.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of antitumor diarylsulfonylureas on in vivo and in vitro mitochondrial structure and functions

Diarylsulfonylureas are novel oncolytic agents shown to have therapeutic activity against both rodent solid tumors and xenografts of human tumors in mice. Previous studies have shown that diarylsulfonylureas localize in mitochondria and cause morphological changes in these organelles. We have investigated the mechanism of action of diarylsulfonylureas, namely, N-(5-indanylsulfonyl)-N'-(4-chlorophenyl)urea (ISCU) and the N-4-methyl analogue (MPCU), by studying their effect on mitochondrial morphology and uptake of rhodamine 123 in GC3/c1 cells in culture and the oxidative phosphorylation in isolated mitochondria from mouse liver, using pyruvate-malate and succinate as substrates. Morphometric analysis of mitochondria in GC3/c1 cells exposed to ISCU showed that ISCU (165 microM) doubled the mitochondrial size after 24-h exposure in culture. Also, ISCU (100 microM), like 40 microM carbonylcyanide p-trifluoromethoxyphenylhydrazone, significantly reduced the rhodamine 123 uptake by GC3/c1 cells studied by flow cytometry. In isolated mitochondria both ISCU and MPCU uncoupled oxidative phosphorylation at 50 microM, with pyruvate-malate as substrate, as was indicated by a significant increase in the State 4 oxygen consumption. This resulted in the loss of ADP phosphorylation and, therefore, the ADP/oxygen ratio was reduced to zero and the respiratory control ratio to one. The succinate oxidation was also significantly impaired by ISCU, causing some decrease in ADP phosphorylation. On the other hand, MPCU did not exhibit any significant effect on the oxidation of succinate. At concentrations of lower than 50 microM, both of these compounds exhibited a deleterious effect, causing damage to mitochondrial functions in the presence of pyruvate-malate as substrates. These data confirm, through morphometric analysis, our previous qualitative observations of abnormal mitochondrial morphology observed in GC3/c1 cells grown in the presence of high concentrations of ISCU and MPCU and further suggest that diarylsulfonylureas, by uncoupling mitochondrial oxidative phosphorylation, may lower cellular ATP. It is probable that this mechanism contributes, at least partially, to cytotoxicity in GC3/c1 cells exposed to high concentrations of ISCU for relatively brief periods (2 to 4 h) and possibly contributes to cytotoxicity at drug concentrations that can be achieved in rodents.

Interaction between 5-fluorouracil, [6RS]leucovorin, and recombinant human interferon-alpha 2a in cultured colon adenocarcinoma cells

Recombinant human interferon-alpha 2a (rIFN-alpha 2a; 500 or 5,000 IU/mL) or [6RS] leucovorin ([6RS]LV; 1 microM) each potentiated the cytotoxic activity of 5-fluorouracil (FUra) by 2.6- to 3.2-fold during 72 hr exposures in two human colon adenocarcinoma cell lines (GC3/c1; VRC5/c1). When all three agents were combined, FUra cytotoxicity was further potentiated by 3.2- to 4.3-fold (total 10- to 14-fold). Potentiation of FUra cytotoxicity occurred at clinically achieveable concentrations of rIFN-alpha 2a and [6RS]LV. Effects were reversed by dThd (20 microM), although the activity of CB3717, a quinazoline-based, specific inhibitor of thymidylate synthase, was not potentiated by rIFN-alpha 2a. Data suggest the requirement of a 5-fluoropyrimidine for biochemical modulation and interaction at the level of thymidylate synthase or DNA.

Rhabdomyosarcoma. From the laboratory to the clinic

The prospect of identifying and developing new agents for treatment of rhabdomyosarcomas is discussed in the light of current prognosis for children with advanced stage disease. Preliminary attempts to identify tumor-specific agents using in vitro cell culture show potential promise, but as yet remain unproven. The more complex system of identifying therapeutically active agents using human tumor xenografts has demonstrated usefulness. The potential problems associated with this system are discussed.

Influence of Extracellular pH on the Accumulation and Cytotoxicity of N-(4-Methylphenylsulfonyl)-N′-(4-chlorophenyl)urea in Human Cell Lines

The effect of extracellular pH (pH(e)) on the accumulation and cytotoxicity of the diarylsulfonylurea antitumor agent N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)urea (MPCU) has been examined. In a human colon adenocarcinoma cell line, GC3/C1, the initial rate of uptake of [3H]MPCU (2.4 microM) was increased by 4.5-fold as pH(e) was reduced from 7.4 to 6.5. Steady state levels of MPCU were inversely proportional to pH(e) and were 5-fold greater at pH 6.0 compared to 7.4. Similar results were obtained using Rh30 cells derived from an alveolar rhabdomyosarcoma. MPCU rapidly re-equilibrated after achieving steady state when pH(e) was altered, indicating that MPCU was not tightly bound within cells. In both cell lines, the uncoupling agent, carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP), significantly reduced (GC3/C1) or completely inhibited (Rh30) accumulation of MPCU at each pH(e) examined. Sodium azide had the same effect on the accumulation of MPCU as FCCP. The effects of FCCP and azide appeared to be due to collapse of the pH differential across the mitochondrial inner membrane rather than the gradient across the plasma membrane. As extracellular pH (pH(e)) decreased, intracellular pH(pH(i)) also decreased in GC3/C1 cells, such that the greatest pH differential (pH(i) - pH(e)) was 0.2 units at pH(e) 6.0. Neither FCCP nor azide significantly altered this pH gradient, indicating a minor role, if any, for the plasma membrane pH gradient in accumulation of MPCU in GC3/C1 cells. The effect of pH(e) (7.4 to 6.0) on cytotoxicity of MPCU was determined after exposure of cells for 4 hr to various concentrations of MPCU in the presence of 10% fetal bovine serum. Decreasing the pH(e) from 7.4 to 6.0 increased the potency of MPCU by 4.7- and 4.5-fold in Rh30 and GC3/C1 cells, respectively. In cells exposed to drug/pH(e) combinations that resulted in 50% reduction in colony forming potential, the steady state levels of [3H]MPCU were similar (range 8.8 +/- 0.9 to 10.56 +/- 0.6 nmol/10(6) cells). These results demonstrate that decrease of pH(e) significantly enhanced the uptake of MPCU accumulation into an FCCP/azide-sensitive compartment, and cytotoxicity of this agent. These data further support the hypothesis that sequestration of diarylsulfonylureas into the FCCP/azide-sensitive compartment (probably mitochondria) was associated with its cytotoxicity. The role of pH(e) in determining therapeutic selectivity of diarylsulfonylureas is discussed.

Myogenic regulatory protein (MyoD1) expression in childhood solid tumors: diagnostic utility in rhabdomyosarcoma

Transcripts for the muscle regulatory gene MyoD1 are expressed during normal skeletal muscle myogenesis and in rhabdomyosarcomas but not in other tissues or in soft-tissue sarcomas. Here we report the distribution of MyoD1 protein, determined by reactivity with anti-MyoD1 polyclonal sera in normal tissues, rhabdomyosarcoma cell lines, and in a variety of pediatric solid tumors. The distribution of MyoD1 protein was highly restricted in normal tissues and was detected only in fetal skeletal muscle and more faintly in adult skeletal muscle. All six human rhabdomyosarcoma cell lines analyzed expressed MyoD1 mRNA transcripts as well as immunoreactive protein. The immunohistochemical expression of MyoD1 protein was then examined in 49 surgical specimens from a variety of pediatric solid tumors. Each of 16 rhabdomyosarcoma specimens was positive for MyoD1, including four that did not express the intermediate filament protein desmin. Two of five specimens originally designated sarcoma type indeterminate (STI) and two of three specimens originally designated extraosseous Ewing's sarcoma (EOE) were positive for MyoD1, suggesting commitment to myogenic differentiation. Three of eight Wilms' tumors, which also expressed desmin and had clearly evident myogenic elements, also were positive for MyoD1. Tumors that failed to express MyoD1 protein included neuroblastoma, primitive neuroectodermal tumor, non-Hodgkins lymphoma, embryonal sarcoma of the liver, malignant fibrous histiocytoma, malignant rhabdoid tumor, and Ewing's sarcoma of the bone. These results indicate that expression of MyoD1 protein is highly restricted in normal human tissues and that expression of this gene product in malignant tissue may be diagnostic for rhabdomyosarcoma. Furthermore MyoD1 staining may be a valuable adjunct in the classification of pediatric soft-tissue sarcomas.

Morphological and molecular characterization of spontaneous myogenic differentiation in a human rhabdomyosarcoma cell line

Skeletal muscle differentiation consists of an ordered withdrawal of committed cells from the cell cycle and their fusion to form multinucleated myotubes. To determine if differentiation of malignant myoblasts parallels that of normal skeletal muscle, a cell line (Rh28) was established from an alveolar rhabdomyosarcoma. Rh28 displays a constant population doubling time of 45-55 h until passage 60, when the doubling time progressively increases until proliferation ceases. Loss of proliferative capacity is associated with morphological evidence of differentiation to multinucleated myotubes, fusion, and the expression of numerous muscle-specific genes. In contrast to normal myogenic differentiation, multinucleated cells continue to synthesize DNA and express abundant c-myc transcripts. These observations suggest synchronous replication and possible arrest in the G2-phase of the cell cycle, since there was no evidence of mitotic activity in differentiated cells. Terminal differentiation of early passage Rh28 cells was induced in the presence of 10% dialyzed fetal calf serum but not by medium containing 2% undialyzed serum, suggesting a role for low molecular weight growth factors in this process. Our data indicate that the Rh28 cell line may be of value in elucidating the relationship between oncogenic transformation and differentiation in rhabdomyosarcoma.

Malignant rhabdoid tumor: a highly malignant childhood tumor with minimal karyotypic changes

Malignant rhabdoid tumors (MRT) are rare; thus very few cytogenetic studies of this type of tumor have been performed. We report the results of cytogenetic studies of 10 MRTs from various anatomic primary sites. Six cases had normal diploid karyotypes with no detectable rearrangements or aneuploidy except for occasional tetraploid cells. In 4 of these cases the tumor phenotype was verified by electron microscopic studies. In a seventh case only normal cells were identified in short-term culture, but a del(13)(q14) appeared after 4 months in culture. A soft tissue MRT contained a translocation, t(8;15)(q12;p11), and a liver MRT contained a del(3)(q21) or t(3;?)(q21;?). The single case of a primary brain MRT had monosomy 22 with deletion of part of the remaining chromosome 22. Our findings indicate that visible chromosomal rearrangements occur in fewer than half of MRTs. When combined with other reported series, our study indicates that monosomy 22 is a non-random chromosomal abnormality in primary MRT of the brain.

Influence of guanine nucleotides on vincristine binding in tumor cytosols and purified tubulin: evidence for an inhibitor of vincristine binding

In cytosols from human rhabdomyosarcoma xenografts, the formation of vincristine (VCR)-tubulin complex and its stability were increased by GTP (Bowman et al.: Biochem. Biophys. Res. Commun., 135:695-700, 1986). We have further examined this modulation to determine whether a) GTP was protecting the VCR binding site from denaturation, b) the enhancement of complex formation was guanosine specific, and c) whether this influence was a direct interaction between GTP, VCR, and tubulin, or was mediated through another factor. In GTP-depleted cytosols from tumor xenografts HxRH18 and HxRh12, VCR binding activity was stable for at least 2 hours at 37 degrees C, indicating that the enhancement of complex formation and stability was not due to protection of tubulin integrity as measured by VCR binding; 10 nM GTP increased complex formation slightly, with complex formation increasing as GTP concentrations were increased to 5 microM, where maximum effect was observed. GTP and GDP (0.1 mM) both increased complex formation three-fold, while GMP, GMP-PNP, and ITP increased formation 1.5-fold. IMP, CTP, and ATP had no significant effect. Therefore, the modulation of VCR binding was relatively specific for the guanine nucleotides GDP and GTP. Microtubule protein, purified from Rh18 and Rh12 tumors by cycles of polymerization-depolymerization, bound VCR rapidly and binding was not influenced by GTP. This suggested that GTP modulation of VCR binding in cytosols was through a soluble factor lost in tubulin purification. In experiments with cytosol fractionated by molecular weight, there was inhibition of VCR binding activity by fractions with an mw range 20-50 kD. This inhibition was decreased by 25% by the addition of GTP. These data suggest that in tumor cytosols there may be competition between VCR and a natural ligand that is modulated by GTP. Two potential models for VCR binding are proposed.

Insulin-like growth factor II acts as an autocrine growth and motility factor in human rhabdomyosarcoma tumors

Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and appears to arise from developing striated muscle-forming cells. Since insulin-like growth factor II (IGF-II) is involved in normal muscle growth and maturation and elevated IGF-II mRNA levels have previously been reported in rhabdomyosarcomas, we have been studying the possible role of IGF-II in the unregulated growth and invasive potential of these embryonal tumors. In this study, we demonstrate that 13 of 14 rhabdomyosarcoma tumors express high levels of IGF-II mRNA relative to normal adult muscle and also express mRNA for the type I IGF receptors on their cell surface, the receptor thought to mediate the effects of IGF-II on muscle cells. We have established several rhabdomyosarcoma cell lines in mitogen-free media and demonstrate that these cells express type I IGF receptors on their cell surface and secrete IGF-II into the media. Exogenous IGF-II is able to stimulate cellular motility in these cell lines as assayed in a modified Boyden chamber. Finally, alpha IR-3, a type I receptor antagonist, inhibits the growth of these cell lines in serum-free media but does not inhibit IGF-II-induced motility of these cells. These data suggest that endogenously produced IGF-II functions as an autocrine growth and motility factor in many rhabdomyosarcoma tumors. The mitogenic actions of IGF-II are mediated through a domain of the type I IGF receptor that is blocked by alpha IR-3. IGF-II-induced motility may be mediated through an alternative signaling pathway.

Influence of dose of [6RS]leucovorin on reduced folate pools and 5-fluorouracil-mediated thymidylate synthase inhibition in human colon adenocarcinoma xenografts

Using preclinical models of human colon adenocarcinomas in immune-deprived mice, the influence of dose of [6RS]leucovorin ([6RS]LV, 20 to 1000 mg/m2) administered by 24-h i.v. infusion was determined on the following parameters: (a) plasma concentrations of the active [6S] and inactive [6R] isomers of [6RS]LV and the biologically active diastereoisomer of 5-methyltetrahydrolate (5-CH3-H4PteGlu); (b) expansion of intratumor pools of 5,10-methylenetetrahydrofolates (CH2-H4PteGlun) and tetrahydrofolates (H4PteGlun), that may influence the binding of 5-fluorodeoxyuridylate to thymidylate synthase; (c) the distribution of polyglutamate forms of CH2-H4PteGlun and H4PteGlun; and (d) (5-fluorouracil (FUra)-mediated thymidylate synthase inhibition in Hx-ELC2, HxGC3, HxVRC5, and HxHC1 tumors. Folypolyglutamate synthetase activities were also determined in each line. Linear increases in plasma concentrations of [6R]LV, [6S]LV, and 5-CH3-H4-PteGlu were determined over the complete range of [6RS]LV doses examined. However, in neoplastic tissues three patterns of biochemical modulation by [6RS]LV were evident. (a) In HxELC2 and HxVRC5 tumors, pools of CH2-H4PteGlun and H4PteGlun were elevated in proportion to the dose of [6RS]LV between dose levels of 50 and 200 mg/m2. Subsequent expansion of these pools continued that was disproportionate to the dose of [6RS]LV until no further increase was observed beyond 800 mg/m2 [6RS]LV, at which point pools were maximally expanded by 4- to 4.5-fold. The extent of retardation of recovery of thymidylate synthase activity increased as the dose of [6RS]LV was increased in both tumors, when FUra (15 or 50 mg/kg), was administered by i.v. bolus injection 3 h into the 24-h infusion of [6RS]LV. This was related to the increase in predominance of CH2-H4PteGlu2-5 with increasing dose of [6RS]LV. (b) For HxHC1 tumors, little expansion of CH2-H4PteGlun and H4PteGlun pools (maximum, 137% of control) was detected at the highest dose levels of [6RS]LV, and no significant modulation of FUra-inhibited thymidylate synthase activity was detected, even at 1000 mg/m2 [6RS] LV. CH2-H4PteGlu5 remained similar or decreased as the dose of [6RS] LV was increased. (c) For line HxGC3, pools of CH2-H4PteGlun and H4PteGlun increased gradually from 169% of control at 20 mg/m2 [6RS] LV to 233% of control at 1000 mg/m2 [6RS]LV, and were intermediate between the expansion observed in HxHC1 in comparison to HxELC2 and HxVRC5 tumors. CH2-H4PteGlu3-5 were elevated at low dose levels of [6RS]LV.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between dose rate of [6RS]Leucovorin administration, plasma concentrations of reduced folates, and pools of 5,10-methylenetetrahydrofolates and tetrahydrofolates in human colon adenocarcinoma xenografts

[6RS]Leucovorin (5-formyltetrahydrofolate; 5-CHO-H4PteGlu) administered in different regimens in combination with 5-fluorouracil (FUra) has increased the response rates to FUra in patients with colon adenocarcinoma. Using preclinical models of human colon adenocarcinomas as xenografts in immune-deprived mice, the effect of the rate of administration of racemic [6RS]leucovorin on the concentration-time profile of reduced folates in plasma, size of intratumor pools of 5,10-methylenetetrahydrofolates (CH2-H4PteGlun) and tetrahydrofolates (H4PteGlun), and the distribution of their polyglutamate species have been examined. Bolus injection i.v., or 4-h or 24-h infusion of [6RS]leucovorin (500 mg/m2) yielded similar concentration profiles of the biologically active [6S] and inactive [6R] isomers of 5-CHO-H4-PteGlu and 5-methyltetrahydrofolate (5-CH3-H4PteGlu) in mouse plasma to those previously reported in humans, but with more rapid elimination half-lives (t1/2 = 11 to 16 min, 23 to 41 min, and 30 to 35 min, respectively). Thus, reduced folates remained elevated in plasma during the period of [6RS]leucovorin administration. In HxELC2 and HxGC3 tumors, pools of CH2-H4PteGlun and H4PteGlun were increased from 350% to 700% of control, but only during [6RS]leucovorin infusion. Intracellular levels subsequently declined rapidly, similar to the loss of reduced folates from plasma. Increasing the rate of [6RS]leucovorin delivery by decreasing the time for administration from a 24-h to a 4-h infusion did not further increase the intratumor pools of CH2-H4PteGlun and H4PteGlun, suggesting saturation in the cellular metabolism of [6RS]leucovorin. In HxGC3 tumors, CH2-H4PteGlu4-5 were elevated more rapidly than in line HxELC2, which accumulated predominantly a shorter chain length species following i.v. bolus injection. During the 4-h infusion schedule, di- and triglutamate species in particular accumulated in both tumors with no elevation in CH2-H4PteGlu5 until the infusion was discontinued, when this species increased as the shorter chain length forms were declining. However, during the 24-h infusion of [6RS]leucovorin, CH2-H4PteGlu3-5 were elevated in tumors. Since these species have been reported to increase the binding affinity of [6-3H]5-fluorodeoxyuridine monophosphate ([6-3H]FdUMP) to thymidylate synthase, and intratumor pools of CH2-H4PteGlun and H4PteGlun were elevated during the 24-h infusion of [6RS]leucovorin, this was considered to be the preferred schedule for administration.(ABSTRACT TRUNCATED AT 400 WORDS)

Expression of the 5.1 H11 antigen, a fetal muscle surface antigen, in normal and neoplastic tissue

The monoclonal antibody 5.1 H11 recognizes an antigen on human fetal muscle and on rhabdomyosarcoma cell lines and xenografts that has been shown to be homologous to the neural cell adhesion molecule. To evaluate its range of expression, we used immunoperoxidase staining of fresh frozen-tissue sections to determine monoclonal antibody 5.1 H11 reactivity in normal and neoplastic tissue. Among normal tissue specimens, intense antibody staining was seen in brain and peripheral nerve, and weaker staining in ganglionic elements of colon. In addition to 26 of 29 rhabdomyosarcoma specimens, 5.1 H11 antibody showed reactivity to 9 of 10 Wilms' tumors, 6 of 6 neural tumors, and 4 of 4 gliomas, and with single specimens of ectomesenchymoma, clear-cell sarcoma of kidney, undifferentiated sarcoma of liver, ovarian fibroma, and neurofibroma. We conclude that the monoclonal antibody 5.1 H11 recognizes an antigen present not only on fetal muscle but on normal brain and nerve as well. In addition to rhabdomyosarcoma, a variety of other tumors, most of which have been previously shown to express neural cell adhesion molecule, also appear to express the antigen recognized by 5.1 H11. Our results thus offer additional confirmatory evidence that an epitope of neural cell adhesion molecule is the antigen for 5.1 H11.

Cellular pharmacology of 5-fluorouracil in a human colon adenocarcinoma cell line selected for thymidine kinase deficiency

A human colon adenocarcinoma cell line (GC3TK-) was selected for thymidine kinase (TK) deficiency from cloned parental cells (GC3C1) by exposure to 5-bromodeoxyuridine (BrdUrd). The cellular pharmacology of 5-fluorouracil (FUra) and the influence of physiological concentrations of thymidine (dThd; 0.1 to 1 microM) on FUra cytotoxicity during brief exposure in both cell lines were examined. The uptake of FUra during a 1-hr drug exposure, its metabolism to ribo- and deoxyribonucleotides, incorporation into RNA, and inhibition of thymidylate synthase were similar in GC3C1 and GC3TK- cells as were the IC50 values for FUra (26 and 23 microM respectively). TK deficiency did not reduce the intracellular concentrations of FdUMP generated from FUra. In GC3C1, at FUra concentrations up to 100 microM, cytotoxicity was prevented by co-administration of dThd (0.1 to 20 microM). The relationship between cell survival and thymidylate synthase inhibition was close under these conditions. At higher drug concentrations, less dThd protection was observed, and none was detected in GC3TK- cells. Thus, the metabolism of FUra did not appear to be altered substantially in GC3C1 cells selected for TK deficiency. Also in these cells, at concentrations of FUra less than 100 microM, FUra cytotoxicity appeared to be mediated via the inhibition of thymidylate synthase.

Development and characterization of pediatric osteosarcoma xenografts

Of 33 surgical specimens of osteosarcoma obtained from 24 patients, eight were established as transplantable tumor lines in immune-deprived CBA/CaJ inbred mice. Each line retained the histological characteristics of the corresponding primary tumor and produced human lactate dehydrogenase isozymes. Volume doubling times, which ranged from a mean of 12.3 +/- 5.6 to 39.3 +/- 9.8 days, were stable for individual lines over multiple passages. Flow cytometric analysis indicated similar cellular DNA content values in the primary human tumors and established xenograft lines; the presence of two separate stem lines, as in the original tumors, was observed in the laboratory models. Comparison of two methods of immune deprivation indicated that thymectomy, whole-body irradiation, and bone marrow reconstitution was associated with a higher rate of successful engraftment than was thymectomy, 1-beta-D-arabinofuranosylcytosine treatment, and whole-body irradiation. Bone marrow-reconstituted mice also showed less variability in tumor volume doubling time. We conclude that osteosarcoma can be heterotransplanted into bone marrow-reconstituted mice with a relatively high success rate and that the xenografts retain features characteristic of the tumors of origin. The availability of these models should prove useful in the development of new therapeutic regimens and in understanding the biology of osteosarcoma.

Studies on the cellular pharmacology of N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)-urea

The cellular pharmacology of N-(4-methylphenylsulfonyl)-N'-(4-chlorophenyl)-urea (MPCU) has been examined in a cloned line of GC3 human colon adenocarcinoma cells. There was a rapid concentrative accumulation of drug, which could be separated into energy-independent and -dependent phases. Accumulation over 15 sec was linear and temperature dependent, but not energy dependent (azide insensitive). The rate of uptake was a linear function of concentration over a wide range (0.0026 to 5 mM). No saturation kinetics were demonstrated. Steady state was achieved within 10 min, and drug levels associated with GC3/C1 cells exceeded the extracellular concentration by 4- to 6-fold. This second phase "concentrative accumulation" of drug was azide sensitive. When cells were incubated to steady state in the presence of azide, removal of azide (with addition of glucose) resulted in a further uptake of sulfonylurea to a higher steady state. When [3H]MPCU was removed from the medium after achieving steady state, loss of drug from cells was rapid (T1/2 approximately 130 sec), and no tight-binding component was apparent. After achieving steady state, cell-associated drug was lost into drug-containing medium reaching a lower steady state if 10 mM azide (+/- glucose) was added. These data indicate that MPCU may enter cells by a non-saturable energy-independent process (passive diffusion) and bind weakly to some intracellular component or become sequestered to some compartment in an energy-dependent manner.