Regulation of N-myristoyltransferase by novel inhibitor proteins

N-myristoylation ensures the proper function and intracellular trafficking of proteins. Many proteins involved in a wide variety of signaling, including cellular transformation and oncogenesis, are myristoylated. The myristoylation of proteins is catalyzed by the ubiquitously distributed eukaryotic enzyme N-myristoyltransferase (NMT). Previously, we reported that NMT activity is higher in colonic epithelial neoplasms than in normal-appearing colonic tissue and that the increase in NMT activity appears at an early stage in colonic carcinogenesis. Furthermore, we observed that NMT expression is elevated in colorectal and gallbladder carcinoma. In our laboratory, an endogenous NMT inhibitor protein (NIP71) was discovered from bovine brain that inhibited NMT activity in rat colonic tumors. Very recently we have demonstrated that the protein NIP71, which is a potential inhibitor of NMT, is homologous to heat-shock cognate protein (HSC70). In addition, we have discovered that enolase is a potent inhibitor of NMT. Further work may elucidate the role of HSC70 and/or enolase in the regulation of NMT, which may lead to the development of a gene-based therapy of colorectal cancer. The interaction of oncoproteomic and oncogenomic data sets through powerful bioinformatics will yield a comprehensive database of protein properties, which will serve as an invaluable tool for cancer researchers to understand the progress of tumorigenesis.     

Expression of N-myristoyltransferase inhibitor protein and its relationship to c-Src levels in human colon cancer cell lines

Earlier, we have reported that N-myristoyltransferase (NMT) activity is higher in colonic epithelial neoplasms than in normal appearing colonic tissue and that increase in NMT activity appears at an early stage in colonic carcinogenesis [Magnuson, B., Raju, R. V. S., Moyana, T. N., and Sharma, R. K. (1995) J. Natl. Cancer Inst. 87, 1630-1635]. In this study, we demonstrate increased NMT mRNA in well-differentiated adenocarcinomas. NMT and c-Src mRNA levels were generally elevated in a subset of human colon cancer cell lines. Western blotting analysis employing N-myristoyltransferase inhibitory protein (NIP(71)) antibody demonstrated low levels of NIP(71) in high-expressing c-Src cell lines and high levels of NIP(71) in low-expressing c-Src cell lines. Interestingly, down regulation of c-Src by antisense expression in the HT-29 cell line resulted in increased expression of NIP(71), suggesting c-Src may negatively regulate NIP(71) expression. Furthermore, this is the first study demonstrating the expression of NIP(71) in human colon cancer cell lines and a possible relationship to colon carcinogenesis.     

Expression of methionine aminopeptidase 2, N-myristoyltransferase, and N-myristoyltransferase inhibitor protein 71 in HT29

Protein myristoylation is a co-translational process, catalyzed by N-myristoyltransferase (NMT) that occurs after the initiating methionine is removed by methionine aminopeptidase (MetAP). The enzymes NMT and MetAP play a major role in the process of myristoylation of oncoproteins including the c-src family. In this study, we examined the levels of expression of MetAP2, NMT, and NMT inhibitor protein 71 (NIP71) in human colon cancer cell lines (HCCLs). We examined the influence of cell density on the expression of the above proteins in HT29 cells. Western blot analysis of MetAP2 and NMT demonstrated higher levels of protein expression in low density of HT29 while low expression in high density was observed. In addition, we observed that NIP71 and pp60(c-src) expressions were dependent on the cell density of HT29. This is the first study demonstrating the expression of MetAP2, NMT, pp60(c-src), and NIP71 in HCCLs.     

Mammalian myristoyl CoA: protein N-myristoyltransferase

Myristoyl CoA:Protein N-myristoyltransferase (NMT) is the enzyme which catalyses the covalent transfer of myristate from myristoyl CoA to the amino-terminal glycine residue of protein substrates. Although NMT is ubiquitous in eukaryotic cells, the enzyme levels and cellular distribution vary among tissues. In this article, we describe the properties of mammalian NMT(s) with reference to subcellular distribution, molecular weights, substrate specificity and the possible involvement of NMT in pathological processes. The cytosolic fraction of bovine brain contains multiple forms of NMT activity whereas bovine spleen contains only a single form. In bovine brain and spleen, the cytosol contained majority of NMT activity. In contrast, rabbit colon and rat liver NMT activity was predominantly particulate. Regional differences in NMT activity have been observed in both rabbit intestine and bovine brain. Results from our laboratory along with the existing knowledge, provide evidence for the existence of tissue specific isozymes of NMT.     

Mechanisms of action of NIP71 on N-myristoyltransferase activity

N-Myristoyl-CoA:protein N-myristoyltransferase (NMT) is the enzyme that catalyses the transfer of myristate from myristoyl-CoA to the N-terminal glycine of protein substrates. NMT was highly purified from bovine brain by procedures involving sequential column chromatography on DEAE-Sepharose CL-6B, phosphocellulose, hydroxylapatite, and mono S and mono Q f.p.l.c.. The highly purified NMT (termed NMT·II) possessed high specific activity with peptide substrates derived from the N-terminal sequences of the cAMP-dependent protein kinase and pp60^src (29,800 and 47,600 pmol N-myristoylpeptide formed/min/mg, respectively), intermediate activity with a peptide based on the N-terminal sequence of a viral structural protein (l) (M2; 17,300 pmol N-myristoylpeptide formed/min/mg) and very low activity with a peptide derived from the N-terminal sequence ofmyristoylatedalanine-richC-kinasesubstrate (MARCKS; 1500 pmol myristoylpeptide formed/min/mg). An NMT protein inhibitor (NIP₇₁) isolated from the particulate fraction of bovine brain (King MJ and Sharma RK: Biochem J 291635-639, 1993) potently inhibited highly purified NMT activity (IC₅₀ 23.7 nM). A minor NMT activity (NMT·PU; 30% total NMT activity), which failed to bind to phosphocellulose, was insensitive to NIP₇₁ inhibition. Inhibition of NMT was observed to be via mixed inhibition with respect to both the myristoyl-CoA and peptide substrates with NIP₇₁ having an apparent higher affinity for NMT than the NMT·myristoyl·CoA complex. Inhibition by NIP₇₁ at subsaturating concentrations of myristolyl-CoA and peptide resulted in a sigmoidal pattern of inhibition indicating that bovine brain possesses a potent and delicate on/off switch to control NMT activity.Abbreviations NMT N-myristoyl-CoA:protein N-myristoyltransferase - NMT·I mono Q N-myristoyl-CoA:protein N-myristoyltransferase peak I - NMT·II mono Q N-myristoyl-CoA:protein N-myristoyltransferase peak II - NMT·III mono Q N-myristoyl-CoA:protein N-myristoyltransferase peak III - NIP₇₁ 71 kDa heat-stable N-myristoyltransferase inhibitor protein     

Purification of Maize Cytosolic 70 kD Stress Protein: a Calmodulin-binding Protein in Plants

The maize cytosolic 70 kD stress protein (HSC70) has been purified by a two-step procedure employing affinity chromatography on ATP-agarose followed by DEAE52 ion-exchange chromatography. Using a biotinylated cauliflower calmodulin (CAM) gel-overlay technique in the presence of 1 mmol/L Ca2+ , the HSCT0 could bind to CAM. No band was shown on sodium dodecyl sulfate-polyacrylamide gel overlayed with biotinylated cauliflower CaM when 1 mmoL/L Ca2+ was replaced by 5 mmol/L EGTA. It indicated that the binding of HSC70 to CaM was dependent on Ca2+. The purified HSC70 inhibited the activity of CaM-dependent NADK and the degree of inhibition increased with augmentation of the HSC70, which appeared to be typically characteristic to CaM- binding protein.     

Mitochondrial precursor protein. Effects of 70-kilodalton heat shock protein on polypeptide folding, aggregation, and import competence

A hybrid precursor protein constructed by fusing the mitochondrial matrix-targeting signal of rat preornithine carbamyl transferase to murine cytosolic dihydrofolate reductase (designated pO-DHFR) was expressed in Escherichia coli. Following purification under denaturing conditions, pO-DHFR was capable of membrane translocation when diluted directly into import medium containing purified mitochondria but lacking cytosolic extracts. This import competence was lost with time, however, when the precursor was diluted and preincubated in medium lacking mitochondria, unless cytosolic proteins (provided by rabbit reticulocyte lysate) were present. Identical results were obtained for purified precursor made by in vitro translation. The ability of the cytosolic proteins to maintain the purified precursor in an import-competent state was sensitive to protease, N-ethylmaleimide (NEM), and was heat labile. Further, this activity appeared to be signal sequence dependent. ATP was not required for the maintenance of pO-DHFR competence, nor did purified 70-kDa heat shock protein (the constitutive form of Hsp70) substitute for this activity. Interestingly, however, purified Hsp70 prevented aggregation of the precursor in an ATP-dependent manner and, as well, retarded the apparent rate and extent of pO-DHFR folding. Partial purification of reticulocyte lysate proteins indicated that competence activity resides within a large mass protein fraction (200-250 kDa) that contains Hsp70. Sucrose density gradient analysis revealed that pO-DHFR reversibly interacts with components of this fraction. Pretreatment of the fraction with NEM, however, significantly stabilized the subsequent formation of a complex with the precursor. The results indicate that Hsp70 can retard precursor polypeptide folding and prevent precursor aggregation; however, by itself, Hsp70 cannot confer import competence to pO-DHFR. Maintenance of import competence correlates with interactions between the precursor and an NEM-sensitive cytosolic protein fraction. Efficient dissociation of the precursor from this complex appears to require a reactive thiol moiety on the cytosolic protein(s).     

Analysis of the compartmentalization of myristoyl-CoA:protein N-myristoyltransferase in Saccharomyces cerevisiae.

Myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyzes the cotranslational, covalent attachment of a rare fatty acid, myristic acid (C14:0), to the amino-terminal glycine residue of a number of eukaryotic proteins involved in cellular growth and signal transduction as well as several viral proteins necessary for assembly-replication. NMT has become a target for both anti-viral and anti-fungal therapy. Analysis of purified Saccharomyces cerevisiae NMT plus yeast strains with conditional lethal nmt1 mutations have provided insights about how this process is regulated in vivo. We have now defined the location of NMT in two strains of S. cerevisiae to better understand the functional and spatial relationships between this enzyme and cellular systems that generate its acyl-CoA and peptide ligands. Western blot studies using an affinity purified antibody raised in rabbits against purified S. cerevisiae NMT indicate that the acyltransferase represents 0.06% of total cellular proteins in an exponentially growing haploid strain with a wild type NMT1 allele. Another strain containing a single, integrated copy of a GAL1/NMT1 fusion gene and a nmt1 null allele had 12-fold higher levels of NMT when grown on galactose-containing media. This increase in NMT production had no detectable effects on growth or cellular morphology. Cell fractionation studies, confocal fluorescence immunocytochemical analysis, and immunogold electron microscopic surveys of fixed, gelatin-embedded cryosections of both strains revealed that NMT is a cytosolic protein that is not associated with cellular membranes (including the endoplasmic reticulum and plasma membrane), the nucleus, mitochondria, Golgi apparatus, or vacuoles. This finding is discussed in light of what is known about the location and activities of enzymes involved in de novo fatty acid biosynthesis and in amino-terminal processing of nascent proteins.     

Immunocytochemical Characterization and Subcellular Localization of Human Myristoyl-CoA: ProteinN-Myristoyltransferase in HeLa Cells

Antisera have been raised to three synthetic peptides based on the sequence of human myristoyl-CoA:proteinN-myristoyl transferase (NMT) and to the purified enzyme following its expression inEscherichia coli.These antisera have been affinity purified and shown to react both with theE. coliexpressed human NMT, and specifically with a protein of molecular weight of 63 kDa in immunoblots of the human cell line HeLa. The affinity purified antibodies have also been used to localize NMT in methanol/acetone permeabilized HeLa cells by immunofluorescent staining. The immunofluorescence showed a diffuse staining pattern throughout the cell, suggesting that the enzyme is predominantly cytosolic. This was confirmed by determining the distribution of NMT activity in different subcellular fractions of HeLa cells. Over 90% of NMT enzymatic activity was released from cell lysates during either hypotonic or isotonic homogenization. However, a small amount of enzymatic activity remained associated with cell membranes, despite extensive washing, and this was confirmed by immunoblot analysis of these membranes for NMT. In comparison, over 99.5% of lactate dehydrogenase activity was released under the same conditions, which suggests that the NMT was genuinely associated with the cell membranes. The membrane-bound enzyme behaved like a peripheral membrane protein. Permeabilization of HeLa cells with 50 μMdigitonin resulted in the release of 90–93% of lactate dehydrogenase compared to 73–85% of NMT, again suggesting that the majority of the enzyme is cytosolic, but that some may be associated with cell membranes or organelles.     

HSPA8/HSC70 chaperone protein

HSPA8/HSC70 protein is a fascinating chaperone protein. It represents a constitutively expressed, cognate protein of the HSP70 family, which is central in many cellular processes. In particular, its regulatory role in autophagy is decisive. We focused this review on HSC70 structure-function considerations and based on this, we put a particular emphasis on HSC70 targeting by small molecules and peptides in order to develop intervention strategies that deviate some of HSC70 properties for therapeutic purposes. Generating active biomolecules regulating autophagy via its effect on HSC70 can effectively be designed only if we understand the fine relationships between HSC70 structure and functions.     

Structural organization of the spinach endoplasmic reticulum-luminal 70-kilodalton heat-shock cognate gene and expression of 70-kilodalton heat-shock genes during cold acclimation.

The 70-kD heat-shock proteins (HSP70s) are encoded by a multigene family in eukaryotes. In plants, the 70-kD heat-shock cognate (HSC70) proteins are located in organellar and cytosolic compartments of cells in most tissues. Previous work has indicated that HSC70 proteins of spinach (Spinacia oleracea) are actively synthesized during cold-acclimating conditions. We have isolated, sequenced, and characterized cDNA and genomic clones for the endoplasmic reticulum (ER) luminal HSC70 protein (immunoglobulin heavy chain-binding protein; BiP) of spinach. The spinach ER-luminal HSC70 is a constitutively expressed gene consisting of eight exons. Spinach BiP mRNA appears to be up-regulated during cold acclimation but is not expressed during water stress or heat shock. In contrast to the differential regulation of mRNA, the ER-luminal HSC70 protein levels remain constant in response to various environmental stresses. Two other members of the spinach 70-kD heat-shock (HS70) multigene family also show differential expression in response to a variety of environmental stresses. A constitutively expressed cytosolic HSC70 protein in spinach appears also to be up-regulated in response to both cold-acclimating and heat-shock treatments. Spinach also contains a cold-shock-induced HS70 gene that is not expressed during heat shock or water stress. Since HSP70s are considered to be involved with the chaperoning and folding of proteins, the data further support the concept that they may be important for maintaining cellular homeostasis and proper protein biogenesis during cold acclimation of spinach.     

A novel inhibitor protein of N-myristoyltransferase from Escherichia coli

Myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyzes the covalent attachment of myristate to the N-terminal of the glycine residue of various eukaryotic and viral proteins of diverse functions. Earlier, we have demonstrated that NMT activity is elevated in colon and gall bladder cancer. Attenuation of NMT activity may prove a novel therapeutic protocol for cancer. We report here a novel inhibitor protein of NMT being expressed in Escherichia coli cells containing the human NMT gene on increasing the incubation period from 5 to 24h. The inhibitor protein was purified by SP-Sepharose column chromatography, heat treatment, ammonium sulfate precipitation, and Superose 12 HR/30 FPLC column chromatography. The inhibitor protein had an apparent molecular mass of 10kDa by gel filtration. It inhibited human NMT in a concentration-dependent manner with 50% inhibition at 640+/-4.68nM. The inhibitor protein showed no direct interaction with myristoyl-CoA and demonstrated no demyristoylase or protease activity. Therefore, we conclude that the inhibitor protein acts directly on NMT.     

Coenzyme A dependent myristoylation and demyristoylation in the regulation of bovine spleen N-myristoyltransferase

N-myristoyltransferase (NMT) is an essential eukaryotic enzyme that catalyzes the transfer of myristate to the NH₂-terminal glycine residue of a number of important proteins of diverse function. Little is known about the control and regulation of NMT in higher eukaryotes. Bovine spleen N-myristoyltransferase has been purified and characterized [Raju, RVS, Kalra J & Sharma RK (1994) J Biol Chem 269:12080–12083]. The activation of bovine spleen NMT with thiol reducing compounds, and its inhibition by the oxidizing agent sodium iodate, suggest a role for oxidation/reduction in NMT regulation. Available knowledge concerning coenzyme A (CoA), the thiol in the cell, indicated that the agents tested on NMT could also reduce or oxidize CoA. The studies suggested that reduced CoA is the key regulator of NMT activity, while oxidized CoA did not allow NMT to promote myristoylation. Further, the process of myristoylation and demyristoylation may be governed by NMT, depending on the differential concentration of CoA. The process of demyristoylation could be blocked by excess CoA. We therefore hypothesize that the initial event in the regulation of NMT is an increase in cellular CoA concentration which could be coupled to an increase in protein myristoylation. Once the CoA concentration in the cell decreases due to oxidation, the demyristoylation process would be operative.Abbreviations NMT N-myristoyl CoA:protein N-myristoyltransferase - hNMT human NMT - YNMT yeast NMT - DTNB N-55 dithiobis(2-nitrobenzoic acid) - DTT dithiothretol - 2-ME 2-mercaptoethanol     

Potential role of N-myristoyltransferase in pathogenic conditions

N-Myristoyltransferase (NMT) is the enzyme that catalyzes the covalent transfer of myristic acid to the N-terminal glycine residue of a protein substrate. In this review article, I summarize that NMT may have a potential role in cardiac muscle in the experimentally induced ischemia-reperfusion rat model and also in the streptozotoein-induced diabetic rat. Both the expression and activity of NMT were increased by ischemia-reperfusion. Immunohistochemical studies showed cytosolic localization of NMT in normal rat heart and predominant nuclear localization after ischemia followed by reperfusion. However, the localization of NMT is reversed by treatment with a calpain inhibitor (ALLM N-Ac-Leu-Leu-methioninal). During ischemia-reperfusion, the degradation of c-Src, which is a substrate of NMT, was observed. These findings suggested that the Src signaling may be impaired in ischemia-reperfusion owing to the altered localization of NMT from cytoplasm to nucleus. Streptozotocin-induced diabetes (an animal model for insulin-dependent diabetes mellitus) resulted in a 2.0-fold increase in rat liver NMT activity as compared with control animals. In obese (fa/fa) Zucker rats (an animal model for non-insulin-dependent diabetes mellitus), there was an approximately 4.7-fold lower liver particulate NMT activity as compared with control lean rat livers. Administration of sodium orthovanadate to the diabetic rats normalized liver NMT activity. These results would indicate that rat liver particulate NMT activity appears to be inversely proportional to the level of plasma insulin, implicating insulin in the control of N-myristoylation. These are the first studies demonstrating the role of NMT in the pathogenesis of ischemia-reperfusion and diabetes mellitus. These conditions remain an important area of investigation.     

Identification and characterization of a 66–68-kDa protein as a methotrexate-binding protein in murine leukemia L1210 cells

We previously observed an unidentified, tyrosine-phosphorylated, membrane-associated, 66–68-kDa protein which was present in the L1210 murine leukemia cells but not present, at least in the tyrosine-phosphorylated form, in cisplatin–methotrexate (CDDP–MTX) cross-resistant L1210/DDP cells. We purified and characterized this 66–68-kDa protein by affinity chromatography purification using its two identified properties, tyrosine phosphorylation and MTX-binding, and yielded a single band of 66–68 kDa. The purified protein was subjected to trypsin digestion and the isolated peptide fragments were sequenced and yielded two partial peptide sequences: VEIIANDQ and VTNAVVTVPAYFNDSQRQA. The two peptide sequences were used to search for the mouse genome at the national center for biotechnology information (NCBI) database for Open Reading Frame Sequence (ORFs) containing these peptides using the TBLASTN function. A single gene was identified containing both sequences, the HSPa8 gene, which codes for the heat shock family protein, HSC70. We further demonstrated that HSC70 is a MTX-binding protein using a binding assay with MTX-agarose beads followed by Western blotting. The HSC70 also existed in various cancer cell lines and showed binding to MTX. Additionally, the HSC70 protein, cloned from the L1210 murine leukemia cells, was expressed and purified from E. coli cells using a polyhistidine-tag purification system and it also showed the binding properties with MTX. DnaK, the HSC70 homologue in E. coli, also binds to MTX. By using the purified truncated HSC70 domains, we identified the adenosine triphosphatase (ATPase) domain of HSC70 that can bind to MTX. Thus, we have tentatively characterized a new, novel property of HSC70 as a MTX-binding protein.     

In vivo modulation of N-myristoyltransferase activity by orthovanadate

N-Myristoyltransferase (NMT) catalyses the transfer of myristate from myristoyl-CoA to the NH₂-terminal glycine residue of several proteins and are important in signal transduction. STZ-induced diabetes (an animal model for insulin-dependent diabetes mellitus, IDDM) resulted in a 2-fold increase in rat liver NMT activity as compared with control animals. In obese Zucker (fa/fa) rats (an animal model for non-insulin dependent diabetes mellitus, NIDDM) there was a4.7-fold lower liver particulate NMT activity as compared with the control lean rat livers. Administration of sodium orthovanadate to the diabetic rats normalised liver NMT activity. These results would indicate that the rat liver particulate N-myristoyltransferase activity appears to be inversely proportional to the level of plasma insulin, implicating insulin in the control of N-myristoylation.Abbreviations NMT N-myristoyl-CoA:protein N-myristoyltransferase - IDDM insulin-dependent diabetes mellitus - NIDDM non-insulin-dependent diabetes mellitus - NIP₇₁ 71 kDa N-myristoyltransferase inhibitor protein - NAF₄₅ 45 kDa N-myristoyltransferase activating factor     

Requirement of N-myristoyltransferase 1 in the development of monocytic lineage

N-myristoyltransferase (NMT) exists in two isoforms, NMT1 and NMT2, that catalyze myristoylation of various proteins crucial in signal transduction, cellular transformation, and oncogenesis. We have recently demonstrated that NMT1 is essential for the early development of mouse embryo. In this report, we have demonstrated that an invariant consequence of NMT1 knock out is defective myelopoesis. Suppressed macrophage colony forming units were observed in M-CSF-stimulated bone marrow cells from heterozygous (+/-) Nmt1-deficient mice. Homozygous (-/-) Nmt1-deficient mouse embryonic stem cells resulted in drastic reduction of macrophages when stimulated to differentiate by M-CSF. Furthermore, to understand the requirement of NMT1 in the monocytic differentiation we investigated the role of NMT, pp60c-Src (NMT substrate) and heat shock cognate protein 70 (inhibitor of NMT), during PMA-induced differentiation of U937 cells. Src kinase activity and protein expression increased during the differentiation process along with regulation of NMT activity by hsc70. NMT1 knock down in PMA treated U937 cells showed defective monocytic differentiation. We report in this study novel observation that regulated total NMT activity and NMT1 is essential for proper monocytic differentiation of the mouse bone marrow cells.     

Differential gene expression of HSC70/HSP70 in yellowtail cells in response to chaperone-mediated autophagy

A cell line derived from the tailfin of the marine teleost yellowtail fish Seriola quinqueradiata was established to examine cellular temperature regulation in an ectothermic animal. Three cytosolic members of the HSP70 family, heat-shock cognate proteins HSC70-1, HSC70-2 and heat-shock protein HSP70, were isolated from cultured yellowtail cells as stress-responsive biomarkers. Expression of hsp70 was heat-inducible, in contrast to the hsc70-1 gene product, which was expressed constitutively. In addition, expression of hsc70-2 was only induced under severe heat-shock conditions. Subcellular fractionation and immunocytochemistry showed localization of HSC70/HSP70 in the lysosomes, indicating that chaperone-mediated autophagy is induced by heat shock. Thus, chaperone-mediated autophagy is assisted by HSC70/HSP70, and heat-inducible expression of the genes encoding these proteins may be responsible for survival and adaptation under heat-shock conditions in fish cells.     

Potential role of N-myristoyltransferase in cancer

Colorectal cancer is the second leading cause of malignant death, and better preventive strategies are needed. The treatment of colonic cancer remains difficult because of the lack of effective chemotherapeutic agents; therefore it is important to continue to search for cellular functions that can be disrupted by chemotherapeutic drugs resulting in the inhibition of the development and progression of cancer. The current knowledge of the modification of proteins by myristoylation involving myristoyl-CoA: protein N-myristoyltransferase (NMT) is in its infancy. This process is involved in the pathogenesis of cancer. We have reported for the first time that NMT activity and protein expression were higher in human colorectal cancer, gallbladder carcinoma and brain tumors. In addition, an increase in NMT activity appeared at an early stage in colonic carcinogenesis. It is conceivable therefore that NMT can be used as a potential marker for the early detection of cancer. These observations lead to the possibility of developing NMT specific inhibitors, which may be therapeutically useful. We proposed that HSC70 and/or enolase could be used as an anticancer therapeutic target. This review summarized the status of NMT in cancer which has been carried in our laboratory.