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L C Panasci

Publications and source records attributed to L C Panasci.

53 records · Page 3Linked to original sources
PubMed1987

Biological activity, binding, and metabolic fate of Ac-[Nle4, D-Phe7]alpha-MSH4-11NH2 with the F1 variant of B16 melanoma cells.

The alpha-MSH (alpha-melanocyte-stimulating hormone) agonist, Ac-[Nle4, D-Phe7]alpha-MSH4-11NH2 (hereafter called ND4-11 alpha-MSH), is at least 10-fold more potent than alpha-MSH as a stimulus of tyrosinase activity in F1 variant cells of B16 melanoma. The binding to these cells during an incubation with 5 nM (3H)ND4-11 alpha-MSH at 37 degrees C is maximal at 0-30 min, 22 fmol/10(6) cells, but declines to 40% of this value at 4 hr. in the presence of 5 nM (3H)ND4-11 alpha-MSH at 37 degrees C, the acid soluble (cell surface) radioactivity decreased rapidly from 11.4 fmol/10(6) cells at 5 min to 4.6 fmol/10(6) cells at 4 hr. Chromatographic analysis of media and cellular samples revealed that there was no evidence of degradation of (3H)ND4-11 alpha-MSH in the medium but there was evidence of intracellular degradation of (3H)ND4-11 alpha-MSH. Ammonium chloride (10mM) resulted in an increase in acid resistant radioactivity (internalized hormone) at 4 hr. The binding to F1 variant cells during an incubation with 0.155 nM or 5 nM (3H)ND4-11 alpha-MSH at 4 degrees C was constant from 4 hr to 24 hr. Under these conditions, there was no time-dependent change in the acid soluble radioactivity from 4 to 24 hr. Scatchard analysis of (3H)ND4-11 alpha-MSH binding to F1 variant cells at 4 degrees C demonstrated that there were approximately 4500 receptors per cell and an association constant of 17.1 nM-1. These results are consistent with a process of (3H)ND4-11 alpha-MSH binding to its receptor followed by internalization of the receptor-hormone complex and then intracellular degradation of the hormone.

Ammonium Chloride↗
PubMed1986

Characterization of L-threonine and L-glutamine transport in murine P388 leukemia cells in vitro. Presence of an N-like amino acid transport system.

The transport of L-threonine and L-glutamine into murine P388 leukemia cells has been characterized. Threonine appears to be a specific substrate for a Na+-dependent amino acid transport system similar to system ASC of the HTC hepatoma cell. Threonine transport is uninhibited by 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid and alpha-(methylamino)isobutyric acid, shows a pattern of transport similar to that seen in HTC hepatoma cells over the pH range of 5.5-7.5, and is inhibited by L-serine and L-cysteine. Approximately two-thirds of glutamine transport into P388 cells also appears to enter P388 cells via this ASC-analogous system. However, based upon (a) inhibition studies with threonine (where the K1 of threonine inhibition of glutamine transport was 7-fold the Km of threonine transport), (b) inhibition analysis of glutamine transport with various amino acids and amino acid analogues, and (c) different patterns of transport between threonine and glutamine over the pH range of 5.5-7.5, approximately one-third of glutamine transport can be attributed to a second Na+-dependent amino acid transport system. This system appears to be similar to the system N of rat hepatocytes. Glutamine and threonine do not appear to enter P388 cells via systems A or L to any significant degree. P388 cells do not appear to exhibit 'adaptive regulation' of amino acid transport. Differences in 'adaptive regulation' could therefore not be utilized for comparing threonine and glutamine transport.

Aminoisobutyric Acids↗
PubMed1986

In vitro comparative studies of the myelotoxicity and antitumor activity of 6-[bis-(2-chloroethyl)-amino]-6-deoxy-D-glucose versus melphalan utilizing the CFU-C and HTSCA assays.

6-[Bis-(2-chloroethyl)-amino]-6-deoxy-D-glucose (C-6) is a new glucose-containing nitrogen mustard that has significant activity for murine P388 leukemia with relative sparing of bone marrow in mice. The in vitro myelotoxicity of C-6 compared with that of melphalan, a clinically active, myelosuppressive nitrogen mustard, was determined in the CFU-C assay in human bone marrow samples obtained from normal volunteers. There was no significant difference between the myelosuppressive actions of C-6 and melphalan at any of the concentrations used except for 4.0 microM, at which C-6 was significantly (P less than 0.05) more toxic than melphalan. Both agents decreased the number of bone marrow cell colonies to approximately 12% of control at 6.6 microM (1 h incubation), which is a good approximation of melphalan's CxT (concentration by time) in man. We used the human tumor stem cell assay (HTSCA) to investigate in vitro antitumor activity. We obtained two specimens of malignant melanoma and two of malignant ovarian carcinoma from patients not previously treated with chemotherapy. The antitumor activity of melphalan was either similar to or greater than that of C-6 at all concentrations utilized against any of the four tumor specimens, except at 1.3 microM for tumor I. In particular, there was no significant difference in the antitumor activities of the two agents at 6.6 microM. These results suggest that C-6 will not be less myelosuppressive than melphalan at doses that produce equivalent antitumor activity in man. In addition, C-6 did not demonstrate increased myelotoxicity for normal human bone marrow cells incubated in glucose-deficient medium as against medium containing 300 mg% glucose at any of the concentrations used. This suggests that C-6 is not transported into normal human bone marrow cells via the glucose transport system, despite the presence of a glucose moiety within the molecule.

Analysis of Variance↗
PubMed1985

Effects of amino acids on the transport and cytotoxicity of melphalan by human bone marrow cells and human tumor cells.

In human tumor cells freshly obtained from patients with breast cancer, ovarian cancer, or adenocarcinoma of unknown etiology and in normal human bone marrow cells, the cell-to-medium ratio (intracellular/extracellular concentration) in vitro of 5.42 microM melphalan rose rapidly to levels of 6-17 after 35 min at 37 degrees C in Dulbecco's phosphate-buffered saline containing bovine serum albumin and glucose. Only patient C (breast cancer) had received chemotherapy. In all cells studied, L amino acids (1 mM) such as leucine, glutamine, tyrosine, and methionine reduced the cell-to-medium ratio of melphalan at 3 and 35 min. There was a good correlation between the reduction of melphalan transport at 35 min in the heterogeneous nucleated bone marrow cell population by amino acids and their effect on melphalan cytotoxicity in the CFU-C system. Aminoisobutyric acid (A1B), a specific substrate of the A system of amino acid transport, at a concentration between 1 and 50 mM had no significant effect on melphalan uptake at 3 min in any of the human cells studied except those of patient C. At 35 min A1B (10 or 50 mM) significantly reduced the intracellular melphalan concentration in normal bone marrow cells and tumor cells from patients B and C. At 2 mM, 2-aminobicyclo-(2, 2,1)-heptane-2-carboxylic acid (BCH), a specific substrate of the L system of amino acid transport, reduced the cell-to-medium ratio to 70% of control at 3 and 35 min in human bone marrow cells. In tumor cells from patients A, B, D, and F, 2 mM BCH had no significant effect on melphalan uptake at 3 min; it slightly decreased uptake in tumor cells from patient C. At 35 min, 2 mM BCH significantly reduced melphalan transport in tumor cells from patients C and F only. The lack of a BCH-suppressible component to melphalan uptake into human tumor cells freshly obtained from previously untreated patients contrasts with the presence of this component in murine L1210 leukemia cells, murine P388 leukemia cells, and human tumor cell lines. This suggests that minor differences in melphalan transport may exist amongst species and also between human tumor cells which are freshly obtained and cell lines maintained in culture.

Adenocarcinoma↗
PubMed1985

Utilization of the HTSCA and CFU-C assay to identify two new 2-chloroethylnitrosourea congeners of amino acid amides with increased in vitro activity against human glioma compared with BCNU.

AspCNU and SarCNU are two amino acid amide congeners (L-asparaginamide and sarcosinamide congeners) of chloroethylnitrosoureas. The in vitro myelotoxicity of these agents compared with BCNU at 1-8 micrograms/ml was determined in bone marrow cells from normal volunteers in the CFU-C assay. AspCNU and SarCNU were significantly (P less than 0.05) less myelotoxic than BCNU at equivalent microgram concentrations. SarCNU or AspCNU at 3 micrograms/ml demonstrate equivalent in vitro myelotoxicity to BCNU 1 microgram/ml. We used the human tumor stem cell assay (HTSCA) to investigate in vitro antitumor activity. We obtained four specimens of malignant glioma and one specimen of meningioma from patients not previously treated with chemotherapy. AspCNU and SarCNU were significantly (P less than 0.05) more active than BCNU at 1-3 micrograms/ml concentrations in the HTSCA in all four malignant glioma specimens. In the one meningioma specimen, BCNU was significantly (P less than 0.05) more active than either AspCNU or SarCNU at all concentrations studied. These results suggest that AspCNU or SarCNU at doses that should produce less myelotoxicity than BCNU may be more active than BCNU against gliomas.

Antineoplastic Agents↗
PubMed1984

Effect of administration of sodium cyanate and melphalan on the lifespan of P388 tumor-bearing CD2F1 mice.

Sodium cyanate (NaOCN) at a dose of 250 mg/kg was shown to decrease protein synthesis in P388 leukemia tumor cells to approximately 52% of control values at 2 h and 32% at 5 h after NaOCN administration, without a corresponding decrease in various normal tissues of the tumor-bearing CD2Fl mice. CD2Fl mice that had received P388 tumor cells IP 1 day prior to drug administration underwent various schedules of treatment with NaOCN and melphalan (MLN). NaOCN (200 mg/kg or 250 mg/kg) administered IP has no significant antitumor activity (increased mean lifespan [ILS] less than 20%). The simultaneous IP administration of NaOCN (250 mg/kg) plus MLN (15 mg/kg) resulted in a significantly greater antitumor activity (approximately 265% of control, with 21 of 30 animals being long-term survivors) than MLN (15 mg/kg) alone (approximately 156% of control, with 11 of 30 animals being long-term survivors). This synergism was not observed when MLN was administered 4 h after NaOCN administration. The synergistic activity of MLN with NaOCN does not appear to be secondary to alterations in the absorption from the peritoneal cavity into the systemic circulation as determined by 3H2O. NaOCN does not increase the intracellular concentration of [chloroethyl-14C]MLN into P388 cells. The mechanism of the synergistic antitumor activity of simultaneous IP administration of NaOCN and MLN is unknown.

Absorption↗
PubMed1983

Comparison of the transport of chlorozotocin and CCNU in L1210 leukemia and murine bone marrow cells in vitro.

The uptake of radiolabeled CLZ and CCNU by L1210 leukemia and murine bone marrow cells was investigated to determine whether the preferential ratio of alkylation of L1210 DNA to murine bone marrow DNA of 1.3 by 0.1 mM CLZ, as against a ratio of 0.6 by equimolar CCNU, is secondary to differences in uptake. The concentration of intact CLZ was determined in the medium and the intracellular water space. The cell: medium ratio (intracellular concentration/medium concentration) of CLZ in bone marrow cells was greater than that seen for L1210 cells. However, the intracellular CLZ concentration generally remained constant in both cell types at 37 degrees C, between 7.0 and 10.0 pmole/microliters. The L1210: murine bone marrow cell ratio of intracellular CLZ concentrations was approximately 1.0 from 10 to 60 min. The intracellular CCNU concentration during the uptake of 0.1 mM (chloroethyl-U-14C) CCNU at 37 degrees C was constant at 85 pmol/microliters from 10 to 60 min in L1210 cells, but slowly decreased from 66 pmole/microliters at 20 min to 43 pmole/microliters at 60 min in bone marrow cells. The L1210: murine bone marrow cell ratio of intracellular CCNU concentrations ranged from 1.45 to 1.98 from 20 to 60 min. Thus, it appears that the preferential ratio of alkylation of L1210 DNA to murine bone marrow DNA by CLZ compared with equimolar CCNU cannot be explained by differences in uptake of the two agents by the two cell types. The uptake of 0.1 mM CLZ at 37 degrees C by L1210 cells in McCoy's 5A medium containing 300 mg% glucose was not affected by the addition of 5 mM cold drug, nor was it affected by the absence of glucose in the medium, with or without cold drug. This suggests that CLZ uptake into L1210 cells is via passive diffusion and that CLZ does not enter these cells via the glucose transport mechanism.

Animals↗
PubMed1980

Pharmacokinetics of vinblastine-loaded platelets utilized in the treatment of platelet-phagocytizing tumors.

Vinblastine-loaded platelets (VLP) have been successfully used in the treatment of idiopathic thrombocytopenic purpura. Three patients with platelet-phagocytizing tumors and thrombocytopenia were treated with VLP. Patient 1 has sustained a response for 11 months. Patient 2 was not evaluable for response because of early death. Patient 3 had a brief partial response. Vinblastine levels were measured by radioimmunoassay in the platelet-rich plasma, platelet-poor plasma, and serum. The pharmacokinetic data obtained on the patients suggest that: (a) the amount of vinblastine bound to platelets in vivo is a function of the platelet-poor plasma vinblastine level and the platelet count; (b) VLP will probably not have any therapeutic advantage, compared with iv vinblastine alone in patients with normal platelet counts; and (c) it appears that delivery of vinblastine was tumor-specific, since the bone marrow serum vinblastine level in patient 2, obtained when the marrow was replaced by tumor cells, was 2.5-fold higher than a simultaneous peripheral blood serum vinblastine level after VLP. Additional studies with VLP appear warranted in patients with platelet-phagocytizing tumors resulting in thrombocytopenia.

Adult↗
PubMed1979

Chlorozotocin. Mechanism of reduced bone marrow toxicity in mice.

Chlorozotocin is a chloroethyl nitrosourea with a glucose carrier that has curative activity for the murine L1210 leukemia, but is nonmyelosuppressive in mice. To determine the mechanism for this unique property of reduced bone marrow toxicity, comparative studies were conducted with chlorozotocin and CCNU, a myelotoxic chloroethyl nitrosourea. Suspensions of L1210 leukemia and murine bone marrow cells were incubated for 2 h with 0.1 mM [(14)C]-chloroethyl chlorozotocin or CCNU. Chlorozotocin demonstrated a fourfold increased covalent binding of the chloroethyl group to L1210 nuclei when compared to equimolar CCNU. Chlorozotocin alkylation of L1210 cells resulted in the binding of 57 pmol of [(14)C]ethyl group/mg of DNA, which represented a 2.3-fold increased alkylation when compared to CCNU. In marked contrast, the binding of the chloroethyl group to bone marrow nuclei was equivalent for both drugs. In addition, chlorozotocin alkylation of murine bone marrow DNA, 45 pmol of [(14)C]ethyl group/mg of DNA, was equivalent to that of CCNU. The ratio of L1210:bone marrow DNA alkylation was 1.3 for chlorozotocin compared to 0.6 for CCNU. The intracellular carbamoylation of L1210 and bone marrow protein by CCNU was 400- to 600-fold greater than that produced by chlorozotocin. After a 2-h exposure to 0.1, 0.05, or 0.01 mM drug, both chlorozotocin and CCNU produced a reduction in the cloning efficiency of L1210 cells that was dose dependent. However, chlorozotocin was significantly more cytotoxic than CCNU at all three molar concentrations (P < 0.01). Chlorozotocin, 0.1 mM, reduced L1210 DNA synthesis to 1% of control by 48 h, in contrast to 16% with equimolar CCNU (P < 0.01). In mice bearing 10(5) L1210 cells, chlorozotocin produced its optimal antitumor activity (332% increased life span [ILS]) at doses of 48-64 mumol/kg, with >50% indefinite survivors. In contrast, CCNU at the same molar doses resulted in only a 191% ILS; a CCNU dose of 128 mumol/kg was required for comparable optimal L1210 antitumor activity, 413% ILS. On a molar basis, the dose of chlorozotocin that produced optimal in vivo L1210 antitumor activity was one-third to one-half that of CCNU. Chlorozotocin, unlike CCNU, produced no murine bone marrow toxicity at its optimal therapeutic dose. This unique combination of antitumor activity without myelosuppression can be correlated with the advantageous ratio of L1210:bone marrow in vitro DNA alkylation by chlorozotocin (1.3) as compared to equimolar CCNU (0.6).

Alkylation↗
PubMed1978

Pharmacologic disposition of chlorozotocin in mice.

Cholorozotocin is a water-soluble chloroethylnitrosourea with the cytotoxic group attached to the C2 position of glucose. The distribution of the alkylating and carbamoylating moieties of the chlorozotocin molecule was determined in mice following the ip administration of an LD10 dose: 20 mg/kg. The half-life (T 0.5) for the plasma disappearance of intact drug was 5 minutes. The plasma disappearance of the ethyl-14C group was biphasic up to 120 minutes after administration; the T 0.5 of the initial phase was 17.5 minutes and the T 0.5 of the prolonged second phase was107 minutes. The disappearance of glucose-14C chlorozotocin followed kinetics similar to the chloroethyl-labeled compound. Fifteen minutes after administration, ethyl-14C drug concentrated maximally in the liver (194 nmols/g of tissue) and the kidney (131 nmols/g of tissue). Uptake into the bone marrow at 60 minutes after ip administration of the ethyl-labeled drug was 6.6 pmols of the ethyl-14C group covalently bound to proteins and nucleic acids per 10(7) nucleated cells. The concentration of ethyl-14C drug in the brain remained at 4 mnols/g of tissue up to 2 hours after administration, reflecting the water-soluble property of this new nitrosourea.

Animals↗
PubMed1977

Biological and biochemical properties of 1-(2-chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea (NSC D 254157), a nitrosourea with reduced bone marrow toxicity.

1-(2-Chloroethyl)-3-(beta-D-glucopyranosyl)-1-nitrosourea (GANU), a water-soluble nitrosourea, differs from 2-[3-(2-chloroethyl)-3-nitrosoureido]-D-glucopyranose (chlorozotocin) by the placement of the cytotoxic group on C-1 of glucose. Its biological and biochemical properties are compared with those of chlorozotocin. At a 10% lethal dose (10 mg/kg i.p.), GANU demonstrates minimal myelosuppression. This dose failed to depress normal bone marrow DNA synthesis, in contrast to a 96% inhibition in L1210 DNA synthesis. In L1210 cell suspension, equimolar doses of GANU and chlorozotocin produced equivalent degrees of inhibition in DNA synthesis. GANU has significant L1210 activity in BALB/c X DBA/2 F1 mice treated on Day 2 of tumor growth. A 117% increased life-span and 15% 45-day survivors are atained with 15 mg/kg i.p., a 50% lethal dose. However, in concurrent studies using randomly selected littermate groups of mice, GANU proved less active than chlorozotocin which produced a 306% increased life-span (15 mg/kg i.p.). GANU and chlorozotocin have similar in vitro alkylating activity but the in vitro carbamoylating activity of GANU is sevenfold that of chlorozotocin. On a molar basis, the lethal toxicity of GANU is twice that of chlorozotocin. The significant carbamoylating activity of GANU may contribute to its greater toxicity and therefore limit the mumoles of alkylating agent that can be administered to the tumor. These structure-activity studies further confirm that the addition of a glucose carrier to a cytotoxic nitrosourea moiety can selectively reduce bone marrow toxicity while retaining antitumor activity.

Animals↗