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1.
Health Phys ; 83(8 Suppl): S36-44, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12132727

ABSTRACT

Health care laser systems offer general laser hazards and additional specific concerns unique to the clinical environment. A formal laser hazard evaluation procedure provides an efficient mechanism for identifying potential laser safety hazards. This paper outlines such a medical laser hazard evaluation program and highlights the unique characteristics of medical lasers.


Subject(s)
Lasers/adverse effects , Radiation Protection , Safety Management , Humans
2.
J Med Chem ; 44(18): 2933-49, 2001 Aug 30.
Article in English | MEDLINE | ID: mdl-11520202

ABSTRACT

The synthesis, structure-activity relationships, and biological properties of a novel series of imidazole-containing inhibitors of farnesyltransferase are described. Starting from a 3-aminopyrrolidinone core, a systematic series of modifications provided 5h, a non-thiol, non-peptide farnesyltransferase inhibitor with excellent bioavailability in dogs. Compound 5h was found to have an unusually favorable ratio of cell potency to intrinsic potency, compared with other known FTIs. It exhibited excellent potency against a range of tumor cell lines in vitro and showed full efficacy in the K-rasB transgenic mouse model.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/chemical synthesis , Enzyme Inhibitors/chemical synthesis , Imidazoles/chemical synthesis , Lactams/chemical synthesis , Nitriles/chemical synthesis , Pyrrolidinones/chemical synthesis , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Binding Sites , Binding, Competitive , Biological Availability , Cell Line, Transformed , Dogs , Drug Design , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Farnesyltranstransferase , Genes, ras , Imidazoles/chemistry , Imidazoles/pharmacology , Lactams/chemistry , Lactams/pharmacology , Mice , Mice, Transgenic , Models, Molecular , Neoplasms, Experimental/pathology , Nitriles/chemistry , Nitriles/pharmacology , Pyrrolidinones/chemistry , Pyrrolidinones/pharmacology , Radioligand Assay , Stereoisomerism , Structure-Activity Relationship
3.
Bioorg Med Chem Lett ; 11(4): 537-40, 2001 Feb 26.
Article in English | MEDLINE | ID: mdl-11229765

ABSTRACT

The evaluation of SAR associated with the insertion of carbonyl groups at various positions of N-arylpiperazinone farnesyltransferase inhibitors is described herein. 1-Aryl-2,3-diketopiperazine derivatives exhibited the best balance of potency and pharmacokinetic profile relative to the parent 1-aryl-2-piperazinones.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Piperazines/pharmacology , Animals , Dogs , Enzyme Inhibitors/pharmacokinetics , Farnesyltranstransferase , Structure-Activity Relationship
4.
Prostate Cancer Prostatic Dis ; 4(1): 33-43, 2001.
Article in English | MEDLINE | ID: mdl-12497061

ABSTRACT

The effects of farnesyl:protein transferase inhibitors (FTIs) were evaluated against hormone-dependent and hormone-independent prostate cancer cell lines harboring mutant and wild type Ras. The combinations of the FTI with hormones and chemotherapy were explored. The effect of FTI on the growth of human prostate cancer lines was examined under anchorage-dependent and -independent conditions. Changes in Ras processing and cellular localization were examined by immunoblotting and immunocytochemistry. Hormone-dependent (LNCaP) and -independent (TSU-Pr1, PC3 and DU145) human prostate cancer cell lines were growth-inhibited by the FTI L-744,832 at concentrations ranging from 100 nM to 20 &mgr;M. The inhibition was accompanied by loss of protein farnesylation and with the accumulation of Ha-Ras as its unprocessed, cytosolic form. No effect on N- and Ki-Ras processing was observed. The transformed phenotype of TSU-Pr1 cells, which possess a Ha-Ras Gly-12-Val activating mutation, reverted following FTI treatment. Enhanced antitumor effects were observed when the FTI was combined with gamma-radiation, etoposide, doxorubicin, cisplatin, estramustine and the antihormone bicalutamide. In particular, the combination of taxol and FTI was synergistic for DU145 cells, a cell line that is only marginally sensitive to the FTI alone. The sensitivity of human prostate cancer cell lines to the FTI is independent of the presence of mutations of tumor suppressors, cell cycle regulators and of the activation of a variety of oncogenes, including Ras. A cell line expressing mutated Ha-Ras is particularly sensitive. Enhanced antitumor effects were observed with an anti-androgen, gamma-irradiation, and several chemotherapeutic agents. These findings support the clinical evaluation of FTIs alone or in combination as treatment for this disease. Prostate Cancer and Prostatic Diseases (2001) 4, 33-43

5.
Radiat Res ; 154(2): 125-32, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10931682

ABSTRACT

Successful radiosensitization requires that tumor cells become more radiosensitive without causing an equivalent reduction in the survival of cells of the surrounding normal tissues. Since tumor cell radiosensitivity can be influenced by RAS oncogene activation, we have hypothesized that inhibition of oncogenic RAS activity would lead to radiosensitization of tumors with activated RAS. We previously showed in tissue culture that prenyltransferase treatment of cells with activated RAS resulted in radiosensitization, whereas treatment of cells with wild-type RAS had no effect on radiation survival. Here we ask whether the findings obtained in vitro have applicability in vivo. We found that treatment of nude mice bearing T24 tumor cell xenografts with farnesyltransferase inhibitors resulted in a significant and synergistic reduction in tumor cell survival after irradiation. The regrowth of T24 tumors expressing activated RAS was also significantly prolonged by the addition of treatment with farnesyltransferase inhibitors compared to the regrowth after irradiation alone. In contrast, there was no effect on the radiosensitivity of HT-29 tumors expressing wild-type RAS. These results demonstrate that specific radiosensitization of tumors expressing activated RAS oncogenes can be obtained in vivo.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Colonic Neoplasms/radiotherapy , Enzyme Inhibitors/pharmacology , Radiation-Sensitizing Agents/pharmacology , Urinary Bladder Neoplasms/radiotherapy , Animals , Colonic Neoplasms/genetics , Farnesyltranstransferase , Gene Expression Regulation, Neoplastic/drug effects , Genes, ras/drug effects , Humans , Methionine/analogs & derivatives , Methionine/pharmacology , Mice , Mice, Nude , Neoplasm Recurrence, Local/pathology , Neoplasm Transplantation , Tumor Cells, Cultured , Tumor Stem Cell Assay , Urinary Bladder Neoplasms/genetics
6.
Cancer Res ; 60(10): 2680-8, 2000 May 15.
Article in English | MEDLINE | ID: mdl-10825141

ABSTRACT

For Ras oncoproteins to transform mammalian cells, they must be posttranslationally modified with a farnesyl group in a reaction catalyzed by the enzyme farnesyl:protein transferase (FPTase). Inhibitors of FPTase have therefore been developed as potential anticancer agents. These compounds reverse many of the malignant phenotypes of Ras-transformed cells in culture and inhibit the growth of tumor xenografts in nude mice. Furthermore, the FPTase inhibitor (FTI) L-744,832 causes tumor regression in mouse mammary tumor virus (MMTV)-v-Ha-ras transgenic mice and tumor stasis in MMTV-N-ras mice. Although these data support the further development of FTIs, it should be noted that Ki-ras is the ras gene most frequently mutated in human cancers. Moreover, Ki-RasB binds more tightly to FPTase than either Ha- or N-Ras, and thus higher concentrations of FTIs that are competitive with the protein substrate may be required to inhibit Ki-Ras processing. Given the unique biochemical and biological features of Ki-RasB, it is important to evaluate the efficacy of FTIs or any other modulator of oncogenic Ras function in model systems expressing this Ras oncoprotein. We have developed strains of transgenic mice carrying the human Ki-rasB cDNA with an activating mutation (G12V) under the control of the MMTV enhancer/promoter. The predominant pathological feature that develops in these mice is the stochastic appearance of mammary adenocarcinomas. High levels of the Ki-rasB transgene RNA are detected in these tumors. Treatment of MMTV-Ki-rasB mice with L-744,832 caused inhibition of tumor growth in the absence of systemic toxicity. Although FPTase activity was inhibited in tumors from the treated mice, unprocessed Ki-RasB was not detected. These results demonstrate the utility of the MMTV-Ki-rasB transgenic mice for testing potential anticancer agents. Additionally, the data suggest that although the FTI L-744,832 can inhibit tumor growth in this model, Ki-Ras may not be the sole mediator of the biological effects of the FTI.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/therapeutic use , Enzyme Inhibitors/therapeutic use , Genes, ras , Growth Inhibitors/therapeutic use , Mammary Neoplasms, Animal/drug therapy , Mammary Tumor Virus, Mouse , Methionine/analogs & derivatives , Animals , Disease Models, Animal , Farnesyltranstransferase , Female , Humans , Methionine/therapeutic use , Mice , Mice, Transgenic , Phenotype , Transgenes
7.
Science ; 287(5460): 1969-73, 2000 Mar 17.
Article in English | MEDLINE | ID: mdl-10720316

ABSTRACT

Cancer as a disease in the human population is becoming a larger health problem, and the medicines used as treatments have clear limitations. In the past 20 years, there has been a tremendous increase in our knowledge of the molecular mechanisms and pathophysiology of human cancer. Many of these mechanisms have been exploited as new targets for drug development in the hope that they will have greater antitumor activity with less toxicity to the patient than is seen with currently used medicines. The fruition of these efforts in the clinic is just now being realized with a few encouraging results.


Subject(s)
Antineoplastic Agents , Chemistry, Pharmaceutical , Drug Design , Neoplasms/drug therapy , Antineoplastic Agents/adverse effects , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Clinical Trials as Topic , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Enzyme Inhibitors/therapeutic use , Genetic Therapy , Humans , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathology , Neoplasms, Hormone-Dependent/drug therapy , Neoplasms, Hormone-Dependent/metabolism
9.
Bioorg Med Chem Lett ; 9(23): 3301-6, 1999 Dec 06.
Article in English | MEDLINE | ID: mdl-10612589

ABSTRACT

The design and syntheses of non-thiol inhibitors of farnesyl-protein transferase are described. Optimization of cysteine-substituted diarylethers led to highly potent imidazole-containing diarylethers and diarylsulfones. Polar diaryl linkers dramatically improved potency and gave highly cell active compounds.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Imidazoles/chemistry , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Ethers/chemistry , Humans , Imidazoles/pharmacology , Magnetic Resonance Spectroscopy , Molecular Structure , Sulfones/chemistry
10.
Blood ; 94(7): 2469-76, 1999 Oct 01.
Article in English | MEDLINE | ID: mdl-10498620

ABSTRACT

Oncogenic RAS alleles encode proteins that accumulate in the guanosine triphosphate (GTP)-bound state. Because post-translational processing of Ras by farnesyltransferase is essential for biologic function, inhibitors of this enzyme have been developed as rational cancer therapeutics. We have investigated farnesyltransferase inhibitor (FTI) L-744,832 in an in vivo murine model of myeloid leukemia that is associated with inactivation of the Nf1 tumor suppressor gene. Nf1 encodes a GTPase activating protein for Ras, and Nf1-deficient (Nf1-/-) hematopoietic cells show hyperactive Ras signaling through the mitogen-activated protein (MAP) kinase pathway. L-744,832 inhibited H-Ras prenylation in cell lines and in primary hematopoietic cells and abrogated the in vitro growth of myeloid progenitor colonies in response to granulocyte-macrophage colony-stimulating factor (GM-CSF). This FTI also partially blocked GM-CSF-induced MAP kinase activation, but did not reduce constitutively elevated levels of MAP kinase activity in primary Nf1-/- cells. Injection of a single dose of 40 or 80 mg/kg of L-744, 832 increased the amount of unprocessed H-Ras in bone marrow cells, but had no detectable effect on N-Ras. Adoptive transfer of Nf1-/- hematopoietic cells into irradiated mice induces a myeloproliferative disorder that did not respond to L-744,832 treatment. We speculate that the lack of efficacy in this model is due to the resistance of N-Ras and K-Ras processing to inhibition by this FTI.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Genes, Tumor Suppressor , Hematopoietic Stem Cells/drug effects , Methionine/analogs & derivatives , Proteins/metabolism , Animals , Cell Division/drug effects , Cells, Cultured , Colony-Forming Units Assay , Crosses, Genetic , Farnesyltranstransferase , Female , Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/metabolism , Leukemia, Myeloid , Leukocyte Count/drug effects , Liver/cytology , Liver/embryology , Male , Methionine/pharmacology , Mice , Mice, Inbred C57BL , Mice, Inbred Strains , Mice, Knockout , Neurofibromin 1 , Protein Prenylation , Proteins/genetics , ras Proteins/metabolism
11.
J Med Chem ; 42(17): 3356-68, 1999 Aug 26.
Article in English | MEDLINE | ID: mdl-10464022

ABSTRACT

Inhibitors of farnesyl protein transferase (FPTase) based upon a pseudotripeptide template are described that comprise an imidazole group substituted with a hydrophobic substituent. (1, 5)-Disubstitution of the imidazole group is shown to be the optimal array that leads to potent and selective inhibitors of FPTase. A variety of aryl and isoprenyl substituents are shown to afford effective inhibitors, and the mechanism by which these compounds inhibit FPTase has been investigated. The biochemical behavior of these compounds suggests that they bind to FPTase at the site usually occupied by the protein substrate. In experiments in cell culture, the methyl ester prodrugs of these inhibitors are cell permeant and potently inhibit the posttranslational modification of H-Ras protein. Additionally, these molecules revert the phenotype of ras transformed cells as evidenced by their ability to slow the growth of ras transformed cell lines in soft agar. One of the inhibitors, as its methyl prodrug, was evaluated in two in vivo models of tumor growth. The compound selectively inhibited the growth of tumors derived from H-ras transformed cells, in nude mice, and caused the regression of preexisting tumors in an H-ras transgenic animal model.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/chemical synthesis , Enzyme Inhibitors/chemical synthesis , Imidazoles/chemical synthesis , 3T3 Cells , Alkyl and Aryl Transferases/metabolism , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Binding Sites , Cell Line, Transformed , Drug Screening Assays, Antitumor , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/metabolism , Enzyme Inhibitors/pharmacology , Imidazoles/chemistry , Imidazoles/pharmacology , Mice , Mice, Nude , Mice, Transgenic , Neoplasm Transplantation , Prodrugs/chemical synthesis , Prodrugs/chemistry , Prodrugs/pharmacology , Protein Processing, Post-Translational/drug effects , Proto-Oncogene Proteins p21(ras)/antagonists & inhibitors , Structure-Activity Relationship
13.
J Med Chem ; 41(23): 4492-501, 1998 Nov 05.
Article in English | MEDLINE | ID: mdl-9804689

ABSTRACT

We have identified a novel fungal metabolite that is an inhibitor of human farnesyl-protein transferase (FPTase) by randomly screening natural product extracts using a high-throughput biochemical assay. Clavaric acid [24, 25-dihydroxy-2-(3-hydroxy-3-methylglutaryl)lanostan-3-one] was isolated from Clavariadelphus truncatus; it specifically inhibits human FPTase (IC50 = 1.3 microM) and does not inhibit geranylgeranyl-protein transferase-I (GGPTase-I) or squalene synthase activity. It is competitive with respect to Ras and is a reversible inhibitor of FPTase. An alkaline hydrolysis product of clavaric acid, clavarinone [2,24,25-trihydroxylanostan-3-one], lacking the 3-hydroxy-3-methylglutaric acid side chain is less active as a FPTase inhibitor. Similarly, a methyl ester derivative of clavaric acid is also inactive. In Rat1 ras-transformed cells clavaric acid and lovastatin inhibited Ras processing without being overtly cytotoxic. Excess mevalonate reversed the effects of lovastatin but not of clavaric acid suggesting that the block on Ras processing by clavaric acid was due to inhibition of FPTase and not due to inhibition of HMG-CoA reductase. Despite these results, the possibility existed that clavaric acid inhibited Ras processing by directly inhibiting HMG-CoA reductase. To directly examine the effects of clavaric acid and clavarinone on HMG-CoA reductase, cholesterol synthesis was measured in HepG2 cells. No inhibition of HMG-CoA reductase was observed indicating that the inhibition of Ras processing by this class of compounds is due to inhibition of FPTase. To date, clavaric acid is the second reported nitrogen-free compound that competes with Ras to inhibit FPTase activity. A series of related compounds derived from computer-based similarity searches and subsequent rational chemical synthetic design provided compounds that exhibited a range of activity (0.04 --> 100 microM) against FPTase. Modest changes in the structures of these inhibitors dramatically change the inhibitory activity of these inhibitors.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antibiotics, Antineoplastic/isolation & purification , Antineoplastic Agents/chemical synthesis , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/isolation & purification , Lanosterol/analogs & derivatives , Protein Prenylation/drug effects , Steroids/chemical synthesis , Animals , Antibiotics, Antineoplastic/chemistry , Antibiotics, Antineoplastic/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Basidiomycota/chemistry , Cell Line , Cholesterol/biosynthesis , Drug Design , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Farnesyl-Diphosphate Farnesyltransferase/antagonists & inhibitors , Humans , Hydrolysis , Hydroxymethylglutaryl CoA Reductases/metabolism , Hydroxymethylglutaryl-CoA Reductase Inhibitors/chemistry , Hydroxymethylglutaryl-CoA Reductase Inhibitors/isolation & purification , Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology , Kinetics , Lanosterol/chemistry , Lanosterol/isolation & purification , Lanosterol/pharmacology , Mice , Rats , Steroids/chemistry , Steroids/pharmacology , Structure-Activity Relationship , ras Proteins/antagonists & inhibitors , ras Proteins/biosynthesis , ras Proteins/genetics
14.
J Med Chem ; 41(14): 2651-6, 1998 Jul 02.
Article in English | MEDLINE | ID: mdl-9651171

ABSTRACT

Inhibitors of Ras protein farnesyltransferase are described which are reduced pseudopeptides related to the C-terminal tetrapeptide of the Ras protein that signals farnesylation. Reduction of the carbonyl groups linking the first three residues of the tetrapeptide leads to active inhibitors which are chemically unstable. Stability can be restored by alkylating the central amine of the tetrapeptide. Studies of the SAR of these alkylated pseudopeptides with concomitant modification of the side chain of the third residue led to 2(S)-(2(S)-¿[2(S)-(2(R)-amino-3-mercaptopropylamino)-3(S)- methylpentyl]naphthalen-1-ylmethylamino¿acetylamino)-4 -methylsulfany lbutyric acid (11), a subnanomolar inhibitor. The methyl ester (10) of this compound exhibited submicromolar activity in the processing assay and selectively inhibited anchorage-independent growth of Rat1 cells transformed by v-ras at 2.5-5 microM.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Esters/chemical synthesis , Molecular Mimicry , Naphthalenes/chemical synthesis , Oligopeptides/chemistry , Prodrugs/chemical synthesis , 3T3 Cells , Animals , Cell Division/drug effects , Cell Line, Transformed , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Esters/chemistry , Esters/pharmacology , Farnesyltranstransferase , Mice , Naphthalenes/chemistry , Naphthalenes/pharmacology , Oncogene Protein p21(ras)/antagonists & inhibitors , Prodrugs/chemistry , Prodrugs/pharmacology , Protein Processing, Post-Translational/drug effects , Rats , Structure-Activity Relationship
15.
Methods Mol Biol ; 84: 283-91, 1998.
Article in English | MEDLINE | ID: mdl-9666457

ABSTRACT

The methods outlined in Subheading 3. provide a logical sequence of assays with which to evaluate the biochemical and biological properties of potential FPTase inhibitors. The clinical predictability of these assays must await the evaluation of one or more of these compounds in humans.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Animals , Enzyme Inhibitors/chemistry , Genes, ras , Humans , Mice , Mice, Nude , Mice, Transgenic , Molecular Biology/methods
16.
Cancer Res ; 58(6): 1253-9, 1998 Mar 15.
Article in English | MEDLINE | ID: mdl-9515813

ABSTRACT

We tested the antineoplastic effect of the farnesyltransferase inhibitor L-744,832 in mammary and lymphoid tumors overexpressing the N-ras proto-oncogene in transgenic mice. Mice bearing mammary tumors were randomly assigned to receive daily 40 mg/kg s.c. injections of this compound (experimental group, n = 6) or vehicle (control group, n = 6) per day for 5.5 weeks. Treatment with the compound significantly reduced the mammary tumor mean growth rate in the experimental group (-0.7 mm3/day), as compared with the control group (+28.2 mm3/day; P < 0.001). There was a significant difference in lymphoma incidence at the end of the treatment between the experimental (0 of 6) and the control (3 of 6) groups (P < 0.05). Therefore, this compound is effective in treating in vivo mammary carcinomas and lymphomas in which an activated N-Ras pathway drives tumorigenesis. The number of apoptotic figures in mammary tumors was significantly higher (P = 0.04) in the experimental (14.7 +/- 8.1) than it was in the control (5.7 +/- 3.5) group, indicating that apoptotic induction could contribute to the mechanism of antitumor activity of this compound. We analyzed the level of processing of N-Ras and H-Ras after immunoprecipitation and Western blotting of protein extracts obtained from mammary tumors treated with L-744,832 or vehicle, either in vivo or in vitro (after primary culture of the same tumors), and from several in vitro treated control cell lines. In all compound-treated mammary tumors and cell lines, H-Ras was mostly unprocessed (more so after in vitro than after in vivo treatment), whereas N-Ras remained mostly processed. Both H-Ras and N-Ras remained fully processed in all vehicle-treated samples. These findings are consistent with a less intense antineoplastic effect of the treatment with the compound in our N-ras model than the effect previously reported for the same compound in H-ras transgenics. In addition, the finding that, in compound-treated mammary tumors, the N-Ras protein remains mainly processed suggests that, in our model, other proteins in addition to Ras may be a target for the compound. Our results and the previous findings of frequent N-ras activation in human hematopoietic malignancies support a role for L-744,832 in the treatment of lymphomas and of mammary carcinomas with an activated N-Ras pathway, as well as the testing of a farnesyl protein transferase inhibitor in humans to establish its clinical relevance.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Genes, ras , Lymphoma/drug therapy , Mammary Neoplasms, Experimental/drug therapy , Proto-Oncogene Proteins p21(ras)/genetics , Proto-Oncogene Proteins p21(ras)/metabolism , Animals , Farnesyltranstransferase , Gene Expression Regulation, Neoplastic , Methionine/analogs & derivatives , Methionine/pharmacology , Mice , Mice, Transgenic , Protein Processing, Post-Translational/drug effects , Proto-Oncogene Mas
17.
Mol Cell Biol ; 18(1): 85-92, 1998 Jan.
Article in English | MEDLINE | ID: mdl-9418856

ABSTRACT

The farnesyltransferase inhibitor L-744,832 selectively blocks the transformed phenotype of cultured cells expressing a mutated H-ras gene and induces dramatic regression of mammary and salivary carcinomas in mouse mammary tumor virus (MMTV)-v-Ha-ras transgenic mice. To better understand how the farnesyltransferase inhibitors might be used in the treatment of human tumors, we have further explored the mechanisms by which L-744,832 induces tumor regression in a variety of transgenic mouse tumor models. We assessed whether L-744,832 induces apoptosis or alterations in cell cycle distribution and found that the tumor regression in MMTV-v-Ha-ras mice could be attributed entirely to elevation of apoptosis levels. In contrast, treatment with doxorubicin, which induces apoptosis in many tumor types, had a minimal effect on apoptosis in these tumors and resulted in a less dramatic tumor response. To determine whether functional p53 is required for L-744,832-induced apoptosis and the resultant tumor regression, MMTV-v-Ha-ras mice were interbred with p53(-/-) mice. Tumors in ras/p53(-/-) mice treated with L-744,832 regressed as efficiently as MMTV-v-Ha-ras tumors, although this response was found to be mediated by both the induction of apoptosis and an increase in G1 with a corresponding decrease in the S-phase fraction. MMTV-v-Ha-ras mice were also interbred with MMTV-c-myc mice to determine whether ras/myc tumors, which possess high levels of spontaneous apoptosis, have the potential to regress through a further increase in apoptosis levels. The ras/myc tumors were found to respond nearly as efficiently to L-744,832 treatment as the MMTV-v-Ha-ras tumors, although no induction of apoptosis was observed. Rather, the tumor regression in the ras/myc mice was found to be mediated by a large reduction in the S-phase fraction. In contrast, treatment of transgenic mice harboring an activated MMTV-c-neu gene did not result in tumor regression. These results demonstrate that a farnesyltransferase inhibitor can induce regression of v-Ha-ras-bearing tumors by multiple mechanisms, including the activation of a suppressed apoptotic pathway, which is largely p53 independent, or by cell cycle alterations, depending upon the presence of various other oncogenic genetic alterations.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Carcinoma/genetics , Enzyme Inhibitors/pharmacology , Mammary Neoplasms, Experimental/genetics , Methionine/analogs & derivatives , Salivary Gland Neoplasms/genetics , Animals , Antineoplastic Agents/therapeutic use , Carcinoma/drug therapy , Carcinoma/pathology , Cell Cycle/drug effects , Enzyme Inhibitors/therapeutic use , Farnesyltranstransferase , Female , Genes, ras , Humans , Mammary Neoplasms, Experimental/drug therapy , Mammary Neoplasms, Experimental/pathology , Mammary Tumor Virus, Mouse , Methionine/pharmacology , Methionine/therapeutic use , Mice , Mice, Transgenic , Salivary Gland Neoplasms/drug therapy , Salivary Gland Neoplasms/pathology
18.
Mol Cell Biol ; 17(8): 4454-64, 1997 Aug.
Article in English | MEDLINE | ID: mdl-9234703

ABSTRACT

Among the mechanisms by which the Ras oncogene induces cellular transformation, Ras activates the mitogen-activated protein kinase (MAPK or ERK) cascade and a related cascade leading to activation of Jun kinase (JNK or SAPK). JNK is additionally regulated by the Ras-related G proteins Rac and Cdc42. Ras also regulates the actin cytoskeleton through an incompletely elucidated Rac-dependent mechanism. A candidate for the physiological effector for both JNK and actin regulation by Rac and Cdc42 is the serine/threonine kinase Pak (p65pak). We show here that expression of a catalytically inactive mutant Pak, Pak1(R299), inhibits Ras transformation of Rat-1 fibroblasts but not of NIH 3T3 cells. Typically, 90 to 95% fewer transformed colonies were observed in cotransfection assays with Rat-1 cells. Pak1(R299) did not inhibit transformation by the Raf oncogene, indicating that inhibition was specific for Ras. Furthermore, Rat-1 cell lines expressing Pak1(R299) were highly resistant to Ras transformation, while cells expressing wild-type Pak1 were efficiently transformed by Ras. Pak1(L83,L86,R299), a mutant that fails to bind either Rac or Cdc42, also inhibited Ras transformation. Rac and Ras activation of JNK was inhibited by Pak1(R299) but not by Pak1(L83,L86,R299). Ras activation of ERK was inhibited by both Pak1(R299) and Pak1(L83,L86,R299), while neither mutant inhibited Raf activation of ERK. These results suggest that Pak1 interacts with components essential for Ras transformation and that inhibition can be uncoupled from JNK but not ERK signaling.


Subject(s)
Cell Transformation, Neoplastic , Genes, ras/physiology , Mitogen-Activated Protein Kinases , Protein Serine-Threonine Kinases/physiology , Animals , COS Cells , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Cell Line , Fibroblasts , GTP Phosphohydrolases/metabolism , GTP-Binding Proteins/genetics , GTP-Binding Proteins/metabolism , JNK Mitogen-Activated Protein Kinases , Mitogen-Activated Protein Kinase 3 , Mutation , Oncogene Proteins v-raf , Protein Serine-Threonine Kinases/genetics , Rats , Retroviridae Proteins, Oncogenic/genetics , p21-Activated Kinases , rac GTP-Binding Proteins
19.
Curr Opin Chem Biol ; 1(2): 197-203, 1997 Aug.
Article in English | MEDLINE | ID: mdl-9667853

ABSTRACT

Over the past few years, the idea that farnesyl-protein transferase (FPTase) inhibitors might be effective antiproliferative/antitumor agents has been realized in studies of cultured cells and in rodent models of cancer. Most of the studies with FPTase inhibitors have focused on inhibiting the growth of ras-transformed cells in vitro or the growth of ras-dependent tumors in mice. More recently, it has been recognized that the antiproliferative effect of FPTase inhibitors may extend beyond ras-driven tumors. It now seems likely that the ability of FPTase inhibitors to reverse the malignant phenotype results, at least in part, from inhibiting the farnesylation of proteins other than Ras.


Subject(s)
Alkyl and Aryl Transferases/antagonists & inhibitors , Antineoplastic Agents/chemistry , Enzyme Inhibitors/chemistry , Genes, ras/drug effects , Farnesyltranstransferase , Humans
20.
Biofactors ; 6(3): 359-66, 1997.
Article in English | MEDLINE | ID: mdl-9288406

ABSTRACT

Ras, a signal-transducing protein involved in mediating growth factor-stimulated proliferation, is mutationally activated in over 30% of human tumors. To be functional Ras must bind to the inner surface of the plasma membrane, with post-translational lipid modifications being necessary for this localization. The essential, first modification of Ras is farnesylation catalyzed by the enzyme farnesyl: proteintransferase (FPTase). Inhibitors of FPTase (FTIs) are currently being tested to determine if they are capable of tumor growth inhibition. Here we describe our efforts, along with those of other groups, in testing the biological and biochemical effects of FTIs.


Subject(s)
Alkyl and Aryl Transferases , Antineoplastic Agents/therapeutic use , Enzyme Inhibitors/therapeutic use , Neoplasms/drug therapy , Transferases/antagonists & inhibitors , Animals , Genes, ras , Humans , Neoplasms/pathology , Protein Prenylation , Transferases/chemistry , Transferases/metabolism , Tumor Cells, Cultured , ras Proteins/metabolism
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