Lectin-like oxidized low density lipoprotein receptor 1-deficient mice show resistance to instability-induced osteoarthritis.

OBJECTIVES: The lectin-like oxidized low density lipoprotein (ox-LDL) receptor 1 (LOX-1)/ox-LDL system, which contributes to the pathogenesis of atherosclerosis, may be involved in the development of osteoarthritis (OA). However, the mechanisms by which the LOX-1/ox-LDL system contributes to OA development in vivo are unclear. In this study, we investigated the direct involvement of LOX-1/ox-LDL in OA development by using LOX-1-knockout (LOX-1(-)/(-)) mice in a joint instability-induced model of OA. METHOD: OA development was evaluated with histological scoring at 4 and 8 weeks after surgery to induce knee destabilization in LOX-1(+)/(+) and LOX-1(-)/(-) mice. Immunohistological analysis was used to evaluate the expression of LOX-1, ox-LDL, Runt-related transcription factor 2 (Runx2), and type X collagen (COL X) in articular chondrocytes and osteophyte-forming cells. In addition, double immunofluorescence staining was performed to determine the relationships between LOX-1 and Runx2 or COL X expression. RESULTS: In the model of knee destabilization, symptoms were significantly suppressed in LOX-1(-)/(-) mice. LOX-1, ox-LDL, Runx2, and COL X were overexpressed in articular chondrocytes and osteophyte-forming cells in LOX-1(+)/(+) mice and were significantly downregulated in articular chondrocytes and osteophyte-forming cells in LOX-1(-)/(-) mice compared with those in LOX-1(+)/(+) mice. Double immunostaining indicated that LOX-1 localization coincided with Runx2 and COL X expression. CONCLUSIONS: These data indicate that the LOX-1/ox-LDL system plays a pivotal role in the pathogenesis of instability-induced OA through endochondral ossification. LOX-1-positive chondrocytes and osteophyte-forming cells may be possible targets to prevent disease progression in OA.

Receptors for T cell-replacing factor/interleukin 5. Specificity, quantitation, and its implication.

T cell-replacing factor (TRF)/IL-5 is a glycosylated polypeptide that acts as a key factor for B cell growth and differentiation. Since IL-5 action is probably mediated by specific cell surface receptor(s), we have characterized the binding of IL-5 to cells using biosynthetically [35S]methionine-labeled IL-5 and 125I-IL-5 that had been prepared using Bolton-Hunter reagent. The radiolabeled IL-5 binds specifically to BCL1-B20 (in vitro line) (a murine chronic B cell leukemic cell line previously shown to differentiate into IgM-secreting cells in response to IL-5) within 10 min at 37 degrees C. There are two classes of binding sites with high affinity (Kd = 66 pM) and low affinity (Kd = 12 nM) for IL-5 and an average number of binding sites for high affinity and for low affinity were 400 and 7,500 per cell, respectively. The specificity of binding of radiolabeled IL-5 has been confirmed by demonstrating that only unlabeled IL-5 and anti-IL-5 mAb but not by IL-1, IL-2, IL-3, IFN-gamma, and GM-CSF inhibit radiolabeled IL-5 binding to BCL1-B20 cells. Treatment of surface-bound radiolabeled IL-5 with bivalent crosslinkers identified a membrane polypeptide of Mr 46,500 to which IL-5 is crosslinked. A variety of cell types have been surveyed for the capacity to bind specifically radiolabeled IL-5 with high affinity. BCL1 cells MOPC104E (murine myeloma cell line) expressed IL-5-R, whereas BAL. 17 and L10 A (B cell lymphoma) did not. T cell line, mastocytoma cell line, or macrophage tumor cell line did not display detectable levels of IL-5-R. were hardly detectable on normal resting B cells but were expressed on LPS-activated B cells, fitting the function of IL-5 that acts on activated B cells for their differentiation into Ig-secreting cells. Intriguingly, early B cell lines (J-87 and T-88) that grow in the presence of IL-5 expressed significant but low numbers of high-affinity binding sites for IL-5. The biological effects of IL-5 were mediated by high-affinity binding sites. The identification and characterization of IL-5-R should provide new insight into the apparent diverse biological activities of IL-5.

Induction of hypertrophic chondrocyte-like phenotypes by oxidized LDL in cultured bovine articular chondrocytes through increase in oxidative stress.

OBJECTIVE: It has been reported that the lectin-like oxidized low-density lipoprotein (Ox-LDL) receptor 1 (LOX-1) is expressed by chondrocytes in osteoarthritis (OA) cartilage and that Ox-LDL binding to LOX-1 increases intracellular oxidative stress in cultured bovine articular chondrocytes (BACs). It was recently demonstrated that reactive oxygen species (ROS) induce hypertrophic differentiation of chondrocytes in the growth plate. It has also been shown that activated chondrocytes in OA have hypertrophic chondrocyte-like phenotypes. The purpose of this study was to determine whether Ox-LDL induces hypertrophic chondrocyte-like phenotypes in BACs. DESIGN: Changes in type X collagen (COL10) and runt-related transcription factor 2 (Runx2) mRNA expression in BACs after Ox-LDL stimulation were investigated using real-time polymerase chain reaction (PCR). Western blotting and immunofluorescent cell staining were used to investigate changes in protein level. The antioxidant N-acetyl cysteine (NAC) was used to ascertain whether oxidative stress is involved in COL10 and Runx2 expression. We induced LOX-1 knockdown cells using small interfering RNA (siRNA) to examine the receptor specificity of Ox-LDL. RESULTS: COL10 expression was upregulated by Ox-LDL in a time- and dose-dependent manner. Immunofluorescent staining showed that Ox-LDL increased COL10 production in the extracellular matrix. Ox-LDL-induced upregulation of COL10 was suppressed by pretreatment with NAC and siRNA. Expression of Runx2 was upregulated by Ox-LDL and H(2)O(2), and these effects were suppressed by NAC pretreatment. CONCLUSION: Ox-LDL binding to LOX-1 induces a hypertrophic chondrocyte-like phenotype through oxidative stress, indicating that Ox-LDL plays a role in the degeneration of cartilage.

Oxidized LDL binding to LOX-1 enhances MCP-1 expression in cultured human articular chondrocytes.

OBJECTIVE: It has been suggested that oxidized low-density lipoprotein (ox-LDL) has some roles in progression of osteoarthritis. The purpose of this study is to investigate whether ox-LDL binding to lectin-like ox-LDL receptor 1 (LOX-1) enhances monocyte chemoattractant protein 1 (MCP-1) expression in cultured human articular chondrocytes (HACs). METHOD: The time course and dose response of MCP-1 mRNA expression and MCP-1 protein release into medium following ox-LDL stimulation were investigated using quantitative Real time PCR (delta-delta Ct method) and enzyme-linked immunosorbent assay (ELISA), respectively. To examine the receptor specificity of ox-LDL action, HACs were preincubated with anti-human LOX-1 monoclonal antibody (TS92). RESULTS: A time-course study revealed that MCP-1 mRNA expression increased 5.09+/-0.86 fold 12h after ox-LDL stimulation compared to time-0. ox-LDL stimulation increased MCP-1 protein level in conditioned medium in a time-dependent manner. Increased MCP-1 level was evident 6h after stimulation, reaching 830+/-91 pg/ml at 24h (33+/-8 pg/ml at time-0). Dose responses of MCP-1 expression were also evident in mRNA and protein levels. Pretreatment with TS92 markedly suppressed these stimulating effects of ox-LDL, although that with non-specific IgG did not. Native LDL did not affect MCP-1 expression. CONCLUSION: Our results suggest that ox-LDL enhances MCP-1 expression in HACs and supports the hypothesis that ox-LDL is involved in cartilage degeneration.

Severe mandibuloacral dysplasia caused by novel compound heterozygous ZMPSTE24 mutations in two Japanese siblings.

Mandibuloacral dysplasia (MAD) is a rare autosomal recessive progeroid syndrome, characterized by mandibular hypoplasia, acroosteolysis affecting distal phalanges and clavicles, delayed closure of the cranial sutures, atrophic skin, and lipodystrophy. Recently, mutations in lamin A/C (LMNA) and zinc metalloprotease (ZMPSTE24), involved in post-translational processing of prelamin A to mature lamin A, have been identified in MAD kindreds. We now report novel compound heterozygous mutations in exon 1 (c.121C>T; p.Q41X) and exon 6 (c.743C>T; p.P248L) in ZMPSTE24 in two Japanese sisters, 7- and 3-year old, with severe MAD and characteristic facies and atrophic skin. The older sister had lipodystrophy affecting the chest and thighs but sparing abdomen. Their parents and a brother, who were healthy, had heterozygous mutations. The missense mutation, P248L, was not found in 100 normal subjects of Japanese origin. The mutant Q41X was inactive in a yeast halo assay; however, the mutant P248L retained near normal ZMPSTE24 activity. Immunoblots demonstrated accumulation of prelamin A in the patients' cell lysates from lymphoblasts. The lymphoblasts from the patients also revealed less intense staining for lamin A/C on immunofluorescence. We conclude that ZMPSTE24 deficiency results in accumulation of farnesylated prelamin A, which may be responsible for cellular toxicity and the MAD phenotype.

Inhibition of human leukocyte migration in agar by 3-M potassium chloride extracts of stomach, colon, and lung cancers.

Inhibition of leukocyte migration in agarose-agar was used as a probe for tumor-associated antigen in 3-M KCl solubilized extracts of gastric, colon, and lung cancers from humans. Twelve of 40 (30%) leukocyte preparations from gastric cancer patients, 10 of 21 (48%) from colon cancer patients, and 7 of 14 (50%) from lung cancer patients were inhibited by their respective histologically homologus cancer extract. However, among 75 preparations from various cancer patients, leukocytes from only 2 gastric cancer patients were inhibited by paired normal gastric tissue extracts. Only 2 of 68 preparations from normal individuals and none of 67 preparations from patients with nonmalignant diseases, such as gastric peptic ulcer, gastritis, colon polyposis, colitis, pulmonary tuberculosis, chronic bronchitis, and sarcoidosis, were inhibited by cancer extracts. These findings suggest the presence in KCl extracts of gastric cancer of presumed tumor-associated antigen(s) that is antigenically distinct from that of either colon or lung cancer.

Isolation of complementary DNA clones for genes exhibiting reduced expression after treatment of mouse teratocarcinoma stem cells with a tumor-promoting phorbol ester.

For the study of the effects of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) on early mammalian cell differentiation, a complementary DNA (cDNA) library was constructed on the poly(A)+RNAs extracted from undifferentiated F9 cells derived from a 129/Sv mouse teratocarcinoma OTT6050, and screening was done for the cNDA sequences corresponding to the mRNAs, the levels of which decreased significantly in the F9 cells after the TPA treatment. From about 80,000 clones screened, 3 different cDNA clones, pFT27, pFT43, and pFT60, were isolated and characterized. Levels of the RNAs hybridizable to these clones were decreased by fourfold to more than fiftyfold within 1-10 hours in the presence of TPA. Northern blotting experiments identified transcripts corresponding to these clones: pFT27 hybridized to 3.0 kb RNA, pFT43 hybridized to 1.5 kb RNA, and pFT60 hybridized to 1.0 kb RNA. The levels of these 3 transcripts were also decreased after treatment of the undifferentiated F9 cells with retinoic acid (RA) and dibutyryl cyclic AMP (cAMP). The TPA-induced as well as the RA- and cAMP-induced decreases in the RNAs hybridizable to pFT27 were regulated at the transcriptional level, whereas similar decreases in the RNAs hybridizable to pFT43 and pFT60 were regulated at the post-transcriptional level. These findings show that TPA treatment shares common effects with RA and cAMP on the undifferentiated F9 cells.

Transcatheter arterial chemoembolization therapy for hepatocellular carcinoma using polylactic acid microspheres containing aclarubicin hydrochloride.

Transcatheter arterial chemoembolization therapy using polylactic acid microspheres containing aclarubicin hydrochloride (ACR) was performed in 62 patients with primary hepatocellular carcinoma. These microspheres were about 200 microns in diameter and contained 10% (w/w) aclarubicin. A single dose of polylactic acid microspheres containing ACR (50-100 mg of ACR) was administered 1 to 8 times with a mean of 2.2 doses (a total of 160 treatments) in 62 patients. Antitumor effects were observed from the decrease in serum alpha-fetoprotein levels (82.1% of the patients) and in two dimensional size of tumor on computed tomography (93.6%). The cumulative survival rate was 54.3% at 1 year, 24.6% at 2 years, and 19.2% at 3 years, respectively, among 59 patients with unresectable tumors. In 3 resected liver specimens, there was a significant accumulation of ACR in the tumor, and severe necroses of the tumors were observed histologically. Systemic toxicity was mild and all patients tolerated this treatment. These results suggest that transcatheter arterial chemoembolization with the use of polylactic acid microspheres containing ACR is a useful tumor-targeting chemotherapy and is effective in the treatment of hepatocellular carcinoma.

Serum carcinoembryonic antigen level increases correlate with tumor progression in patients with differentiated gastric carcinoma following noncurative resection.

Serum carcinoembryonic antigen (CEA) levels were determined serially in 30 preoperative and postoperative patients with differentiated and 47 with undifferentiated gastric cancers. Macroscopic noncurative resection of the stomach was done for those patients. There was no difference between survival curves in the differentiated and undifferentiated cases, and the 50% survival was 13.1 months for the differentiated group and 12.5 months for the undifferentiated group. Preoperative serum CEA levels were 10.4 +/- 5.2 ng/ml for the differentiated and 4.0 +/- 1.6 ng/ml for the undifferentiated cases, and CEA-positive rates were 20.0% for the differentiated and 14.9% for the undifferentiated cases. There was no difference in preoperative CEA values with regard to tissue types. In the course of tumor progression, CEA levels increased during the first postoperative year in the differentiated cases and related reciprocally to decreases in survival rates. Little change was noted in the undifferentiated cases. Therefore, the serial postoperative assay of serum CEA levels has predictability with regard to tumor progression in patients with a differentiated gastric cancer.

Effects of 1,3-chelation induced by cis-diamminedichloroplatinum(II) on the stability of DNA duplexes.

Several 1,3-intra-strand cross-linked decadeoxynucleotide duplexes, modified with cis-diamminedichloroplatinum(II) (cis-DDP), and their base substitution analogues at the complementary site to the intervening base of the coordination sites, were synthesized and measured for UV-melting profiles to determine melting temperature (Tm) values. The results indicated the thermal stability of the oligonucleotide duplexes containing Pt-induced 1,3-intra-strand cross-linking did not depend on the kind of intervening base of the coordination site but rather on its complementary base. These results may explain the mutagenicity of cis-DDP from a chemical aspect.

Reduced bone marrow toxicity of neocarzinostatin by conjugation with divinyl ether-maleic acid copolymer.

Neocarzinostatin (NCS) was conjugated with divinyl ether-maleic acid anhydride copolymer (pyran copolymer), and its therapeutic effect was compared with that of NCS. The conjugated NCS (pyran-NCS) with a molecular weight of about 23,000, exhibited in vitro cytotoxic activity against eight cell lines and bone marrow cells that was similar to the cytotoxic activity of NCS on a molar basis. Furthermore, both drugs had similar effects against a multidrug-resistant Chinese hamster ovary cell line (CHR C5) and its parent cell line (AUXB1) in vitro. However, pharmacological analysis showed that pyran-NCS had reduced accumulation in the spleen, and most important was three times less hematotoxic in vivo compared with NCS. Also, pyran-NCS had a 1.7-fold higher 50% lethal dose (LD50). Antitumor activity of pyran-NCS and NCS was tested against two different forms of Meth A tumor. In a solid tumor model, pyran-NCS and NCS suppressed tumor growth at three-fourths of the LD50 to 12.8 and 19.0% of the control tumor as evaluated on day 28, respectively (P less than 0.025). In an ascitic tumor model, the percentage increase in the median life span caused by pyran-NCS and NCS was more than 400 and 150% on day 60, respectively. Pyran-NCS is more effective than NCS because the reduced acute toxicity permits an increased drug dosage.

Effects of combination anti-vascular endothelial growth factor receptor and anti-epidermal growth factor receptor therapies on the growth of gastric cancer in a nude mouse model.

We hypothesised that the combination of anti-angiogenic and anti-epidermal growth factor (EFG)-receptor (R) therapies would more effectively inhibit gastric cancer growth than single-agent therapy. TMK-1 gastric cancer cells were injected into the gastric wall of nude mice to generate tumours. After 4 days, mice were randomly assigned to the following groups: control, DC101 ([vascular endothelial growth factor (VEGF)-receptor (R)-2 antibody], C225 (EGF-R antibody), or a combination of DC101 and C225. The combination therapy significantly inhibited gastric tumour growth compared with the control group, whereas the decrease in tumour growth in mice treated with DC101 or C225 alone did not reach statistical significance. All mice administered DC101 demonstrated decreased tumour vascularity and increased endothelial cell apoptosis. C225 alone did not affect angiogenesis, but inhibited tumour cell proliferation. The combination therapy led to a further decrease in tumour cell proliferation. The combination of anti-VEGF-R and anti-EGF-R therapies was effective in inhibiting gastric cancer growth. These findings support the hypothesis that inhibiting multiple biological pathways that mediate tumour growth may be an effective therapeutic strategy.

Changes in production of interleukin-1 and interleukin-2 associated with obstructive jaundice and biliary drainage in patients with gastrointestinal cancer.

Increased susceptibility to infection in patients with obstructive jaundice has been well documented in vitro and in vivo. Nevertheless, an underlying mechanism for immunocompromise in these patients has not been identified. This study was undertaken to evaluate the production of two important immunoregulatory molecules, interleukin-1 (IL-1) and interleukin-2 (IL-2), by peripheral blood mononuclear cells in cancer patients with obstructive jaundice before and after percutaneous transhepatic biliary drainage (PTBD). After decompression with PTBD, IL-1 and IL-2 production was significantly increased (IL-1: from 7.9 +/- 4.9 to 13.9 +/- 4.9 U/ml, p less than 0.05; IL-2: from 8.8 +/- 4.9 to 14.1 +/- 6.5 U/ml, p less than 0.05). There was a positive correlation between IL-1 and IL-2 production (r = 0.424, p less than 0.05). The production of both interleukins correlated negatively with serum total bilirubin level (IL-1 r = -0.478, p less than 0.05; IL-2: r = -0.482, p less than 0.05) and positively with high-density lipoprotein cholesterol in serum (IL-1: r = 0.505, p less than 0.01; IL-2: r = 0.494, p less than 0.05). IL-2 production also correlated positively with serum albumin levels (r = 0.511, p less than 0.01). These results suggest that hyperbilirubinemia and abnormal lipid metabolism may be associated with impaired interleukin production, which may result in an increased susceptibility to infection during obstructive jaundice.

Action of Escherichia coli heat-stable enterotoxin II on isolated sections of mouse ileum.

When Escherichia coli STII was applied to the serosa of the ileum at a concentration of 40 micrograms/ml, an acceleration of the spontaneous motility and a weak contraction were induced 2-3 min later. The induction was not affected by the addition of atropine (10(-6) M), but was abolished by the addition of papaverine (10(-4) M). When STII was applied to the mucosa, the acceleration of the spontaneous motility appeared 7-8 min later, but a contraction was not induced. These results suggest that STII acts directly on muscle cell of the ileum and enhances the spontaneous motility of the intestine.

Effects of glucagon on myoelectrical activity of the stomach of conscious and anesthetized dogs.

Effects of glucagon on gastric electrical and mechanical activities recorded by means of a chronically implanted suction electrode and a force strain gauge transducer were examined in conscious and anesthetized dogs. Glucagon (1-10 micrograms/kg) induced inhibition of gastric electrical activity together with mechanical activity in conscious dogs. The plasma glucagon level following exogenous glucagon administration which induced the inhibitory effects on electrical and mechanical activities was over 5 ng/ml. alpha- and beta-adrenoceptor blocking agents did not significantly alter the inhibitory effect of glucagon. Changes in plasma concentrations of glucose, cAMP, insulin, gastrin and catecholamines after glucagon administration were not correlated with the inhibitory action of glucagon on the gastric electrical and mechanical activities. Glucagon at higher concentrations (10(-6) -5 x 10(-6) g/ml) did not produce appreciable changes in motility of the canine gastric strips in vitro. In an anesthetized condition, the inhibitory action of glucagon was completely abolished. Results indicate that exogenously applied glucagon possibly acts directly on the central nervous system, and thus resulted in the inhibition of the gastric electrical and mechanical activities.

Partial purification and characterization of CA19-9 antigen from the ascitic fluid of a patient with pancreatic cancer.

CA19-9 immunoreactive protein was partially purified from the ascitic fluid of a patient with pancreatic cancer by perchloric acid fractionation, gel chromatography and Affi-gel Blue column chromatography, resulting in a purified sample of 5.0 x 10(6) CA19-9 units per milligram of protein (3700-fold purification). Western blotting analysis of this purified sample revealed a single band of molecular weight 210 kDa. Although the original ascitic fluid showed a high CA125 immunoreactivity, this purified sample had no CA125 immunoreactivity. The elution pattern for CA19-9 activity on Affi-gel Blue column is quite distinct from that for CA125. These results suggest that CA19-9 antigen in carcinoma patients may be identical or very similar to that recently purified from the culture media of the colorectal cell line SW1116 and is distinct from CA125 antigen.

Cutaneous mycosis caused by Paecilomyces lilacinus.

A 20-year-old woman had erythematous scaly plaques persistent for 15 years on the left cheek. Cultures from scales and biopsy specimens on Sabouraud's glucose agar repeatedly yielded floccose lilac colonies, and those on a Czapek's solution agar plate developed deep purplish red pigment, which is characteristic of Paecilomyces lilacinus. The PAS stain of the tissue section showed ovoid, divergent, or club-shaped fungal elements among the inflammatory cells or in giant cells. Two months after the patient and a control subject were inoculated with the isolates, P lilacinus could be reisolated from the patient only. Oral administration of griseofulvin significantly reduced erythema and papules. This is the first report, to our knowledge, of deep cutaneous mycosis caused by P lilacinus.

Clinicopathological analysis of synchronous multiple gastric carcinoma.

Clinicopathological analysis was performed on 839 cases surgically resected for gastric carcinoma. The incidence of multiple gastric carcinoma was 4.8% (40 cases, 97 lesions). Multiple carcinoma was more frequently observed in early than in advanced carcinoma (P less than 0.01). The rate of intestinal type lesions was significantly (P less than 0.01) higher in multiple than in single gastric carcinoma, and all of the intestinal type carcinoma correlated with intestinal metaplasia, which is assumed to be closely related to pyloric and atrophic fundic gland area. Eight cases (20.0%) of multiple carcinoma were both in the upper one-third and lower one-third of the stomach. Twenty-nine (51.9%) of the accessory lesions were not detected pre-operatively; 12 (21.1%) of them were detected only by postoperative histology. Twelve (48.0%) of 25 early cancerous foci located in the anterior wall and greater curvature were overlooked before operation. These results indicate that the whole stomach must be carefully examined to detect accessory carcinoma before gastric surgery, especially for intestinal type carcinoma, with greater attention paid to the anterior wall and greater curvature, and that complete removal of the pyloric and atrophic fundic gland area would be required for distal gastrectomy.

Endotoxin inactivation by the humoral components in the tolerant rat serum.

A rapid inactivation of endotoxin has shown to occur following its incubation in serum obtained from endotoxin-tolerant rats with the aid of the limulus amebocyte lysate (LAL) assay. The tolerant rat had large quantities of lipopolysaccharide inhibitor (LPSI) activity, which does not appear to be complement. Heating tolerant rat serum for 60 min at 56 degrees C or the addition of lead acetate to the tolerant serum both resulted in the loss of LPSI activity. This paper focuses on the most unique properties of LPSI, namely it's alteration of activity after heating or the addition of lead acetate, compared with those properties of inhibitors for endotoxin which have been previously demonstrated by a number of investigators.

Cytotoxicity of smancs in comparison with other anticancer agents against various cells in culture.

The cytoxicity of neocarzinostatin (NCS) and smancs [copoly(styrene maleic acid)-conjugated NCS] to various cultured cells was compared with that of several other antitumor agens in clinical use on various malignant and non-malignant cells as regards to their effect on colony formation of cells. Both NCS and smancs showed the most potent cytotoxicity against all tumor cell lines tested; the IC50s (colony inhibitory concentration 50%) of these drugs were 3.2-20 nM, 10-1000 times lower than those of other drugs. In contrast, NCS and smancs exhibited relatively lower toxicity to normal cells such as human skin fibroblasts and chick embryonic fibroblasts (IC50, about 50 and 100 nM, respectively). Normal rat hepatocytes were found to be very resistant to NCS and smancs (both IC50s were about 500 nM). Moreover, the minimum exposure time of smancs to cultured tumor cells required to achieve effective cytotoxic activity was much shorter than that of NCS and other drugs. Namely, at 30 nM more than 80% cells were killed by exposure to smancs for only a few minutes, whereas with NCS more than 80 min of exposure time was required. It was also found that smancs inhibited the uptake of 3H-thymidine into DNA as expected. These results clearly indicate that smancs is an unique antitumor agent with a broad antitumor spectrum which exhibits some characteristics similar to, but also some very different from NCS.