Expression cloning of NaDC-2, an intestinal Na(+)- or Li(+)-dependent dicarboxylate transporter

A cDNA coding for a Na(+)-dicarboxylate cotransporter from Xenopus laevis intestine, NaDC-2, was isolated by functional expression cloning in Xenopus oocytes. NaDC-2 encodes a 622-residue polypeptide with a predicted mass of 68.6 kDa. The sequence and secondary structure of NaDC-2 are related to the mammalian renal Na(+)-dicarboxylate and Na(+)-sulfate cotransporters. NaDC-2 mRNA is expressed only in the intestine. Oocytes injected with NaDC-2 cRNA exhibit increased transport of succinate, citrate, and glutarate. Transport of succinate by NaDC-2 is stimulated by Na+ or Li+, with Michaelis-Menten constant values for succinate of 0.3 mM (in Na+) and 0.7 mM (in Li+). Na+ and Li+ activation curves show sigmoid kinetics, with Hill coefficients of 1.4 (nNa) and 1.7 (nLi), indicating that multiple cations are involved in the transport of succinate. The transport of succinate by NaDC-2 is insensitive to pH, whereas the transport of citrate is inhibited at high pH. The differences in functional properties between NaDC-2 and the structurally related Na(+)-dicarboxylate cotransporters NaDC-1 and hNaDC-1 will form the basis of detailed structure-function studies.

Ketamine-induced peripheral analgesia in rats

AIM

To examine whether ketamine may directly act at peripheral nociceptors to produce analgesia.

METHODS

Wistar rats were anesthetized with urethane. As a nociceptive flexion reflex (FR), C responses from the posterior biceps semitendinosus (PBST) muscle was evoked by electrical stimulation (2 ms, 80 V, 2-3 pulses, 0.5 Hz) via a pair of stainless steel needles inserted subcutaneously applied to the two toes of ipsilateral hindpw.

RESULTS

Subcutaneous injection of ketamine (36 mmol.L-1, 5 microL) into the ipsilateral hindpaw produced an inhibition of C responses. At 9 min after application of ketamine, injection of naloxone (1%, 5 microL) into the same area annulled ketamine-induced inhibition.

CONCLUSION

Ketamine as a dissociate anesthetic acts on peripheral nociceptors to produce analgesia, which is related to activity of peripheral opioid receptors.

Isolation of a gene encoding nodulin-like intrinsic protein of Escherichia coli

Members of the membrane intrinsic protein (MIP) family are expressed in various organisms including plants, insects, and vertebrates. E. coli is known to have a MIP member gene, glycerol facilitator (G1pF). Here we report the isolation of E. coli gene encoding BniP, bacterial nodulin-like intrinsic protein. BniP encodes a 231 amino acid, 24 kDa protein with 42% amino acid identity to Nod26, 38% amino acid identity to AQP1, and 29% amino acid identity to G1pF. Analysis of deduced amino acid sequence predicted a hydrophobic protein with six membrane-spanning domains. Expression of BniP in Xenopus oocytes induced slight increase in osmotic water permeability, but not glycerol or ion permeability. Our results showed that BniP is a new member of the MIP channel-forming proteins of E. coli.

Relationship of p53 alteration and myc family gene overexpression with the clinical characteristics of lung cancer

OBJECTIVE

To evaluate the relationship of p53 alteration and myc family gene overexpression with the clinical characteristics of lung cancer.

METHODS

A series of 59 resected primary lung cancer specimens was analyzed for p53 gene by DNA/PCR sequencing and immunohistochemistry technique, and for myc family genes by RT-PCR methods.

RESULTS

Thirty-seven of 57 tumors were found to have p53 mutations or/and p53 protein accumulation. The presence of p53 alteration was not related to tumor size, lymph node metastasis, stage and relapse. Forty-seven cases were analyzed for myc family genes. The results showed that there was a positive correlation between unregulative expression of myc genes and the above mentioned clinical parameters. Our finding also showed that 19 of 30 cases (63%) with p53 alteration had myc gene overexpression which occurred in 63% and 76% cases with stage III and relapse, respectively, which was higher than 27% and 22% with p53 alteration but no myc gene overexpression and 50% and 71% with p53 negative but myc gene overexpression.

CONCLUSIONS

p53 alteration is a vital genetic event in the earlier stage of lung carcinogenesis, but not a prognostic marker. myc family genes overexpression may be regarded as one of the independent prognostic determinants in lung cancer. The cooperation between p53 alteration and myc gene overexpression may occur during progression of lung cancer, but prognostic determinant is myc gene overexpression.

[Relationship of mdr1 gene expression and multidrug resistance of primary lung cancer]

OBJECTIVE

To evaluate the expression of mdr1 gene in various type of primary lung cancer.

METHOD

A serious of 48 resected primary lung cancer tissues from 5 post-chemotherapy and 43 untreated patients and 33 adjacent normal lung tissues were analyzed for mdr1 gene by RT-PCR method.

RESULTS

Fifteen of 48 tumor tissues were found to have overexpression of mdr1 gene, comprising 6 of 12 adenocarcinomas, 7 of 22 squamous cell carcinomas, 1 of 2 sarcocarcinomas, 1 of 12 small cell carcinomas. Of 5 post-chemotherapy specimens, only one case showed positive. In addition, 3 of 33 adjacent normal tissues also showed mdr1-positive. Overexpression of mdr1 gene did not be associated with tumor size, metastasis and stage of lung cancer. The relapse rate with mdr1-positive cases was higher (80%) than that with mdr1-negative (58%) by one year follow-up of these patients.

CONCLUSION

Overexpression of mdr1 gene can be detected in untreated primary lung cancer, specially in non-small cell lung cancer and may be regarded as one poorly prognostic marker.

Cloning and characterization of the beta subunit of human proximal sequence element-binding transcription factor and its involvement in transcription of small nuclear RNA genes by RNA polymerases II and III

The proximal sequence element (PSE)-binding transcription factor (PTF), which binds the PSE of both RNA polymerase II- and RNA polymerase III-transcribed mammalian small nuclear RNA (snRNA) genes, is essential for their transcription. We previously reported the purification of human PTF, a complex of four subunits, and the molecular cloning and characterization of PTF gamma and delta subunits. Here we describe the isolation and expression of a cDNA encoding PTF beta, as well as functional studies using anti-PTF beta antibodies. Native PTF beta, in either protein fractions or a PTF-Oct-1-DNA complex, can be recognized by polyclonal antibodies raised against recombinant PTF beta. Immunodepletion studies show that PTF beta is required for transcription of both classes of snRNA genes in vitro. In addition, immunoprecipitation analyses demonstrate that substantial and similar molar amounts of TATA-binding protein (TBP) and TFIIIB90 can weakly associate with PTF at low salt conditions, but this association is dramatically reduced at high salt concentrations. Along with our previous demonstration of both physical interactions between PTF gamma/PTF delta and TBP and the involvement of TFIIIB90 in the transcription of class III snRNA genes, these results are consistent with the notion that a TBP-containing complex related to TFIIIB is required for the transcription of class III snRNA genes, and acts through weak interaction with the four-subunit PTF.

[Data analysis on the causes of death through disease surveillance program in Gansu province in the early 1990's]

In order to observe the changes of the causes of death among the residents in Gansu, mortality and years of porential life lost (YPLL) are used in this article to analyse the data of causes of death in 1990-1994. Data indicates that the average mortality of residents was 591.98 per 100,000. The main sequence were as below: respiratory diseases, cardiorasculor and cerebrovascalar diseases, neoplasms, injuries and pediatric diseases. Chronic diseases take up 74.4% of an mortalities. Average YPLL was 55.84/1000. YPLL sequence was as follows: injuries, neoplasms, respiratory system diseases, infectious diseases, cardiorascular diseases.

Structure of aquaporin-2 vasopressin water channel

Aquaporin-2 (AQP-2) is a vasopressin-regulated water channel in the kidney collecting duct. AQP-2 is selectively permeable to water molecule and is translocated between the apical membrane and subapical endosomes in response to vasopressin. To investigate the localization and structure of the aqueous pathway of the AQP-2 water channel, a series of site-directed mutants was constructed and functionally analyzed. Insertion of N-glycosylation reporter sequence into each hydrophilic loop (HL) indicated that AQP-2 has a six-membrane spanning topology and that insertional mutations in HL-2 or HL-5 do not alter water channel function. Mercury-sensitive site of AQP-2 is located near the second asparagine-proline-alanine (NPA) domain at cysteine 181, but not near the first NPA domain. Replacement of HL-3 or HL-4 with the corresponding part of Escherichia coli glycerol facilitator abolished water channel function without changing plasma membrane expression of the channel protein. Introduction of cysteine residues in His-122, Asn-123, Gly-154, Asp-155, or Asn-156 induced partial mercury sensitivity, and point mutations in asparagine 123 significantly altered water permeability. Our results implicate that the structure of AQP-2 is different from models previously proposed for AQP-1 and that HL-3 and HL-4 are closely located to the aqueous pathway.

[Analysis on the health status of residents from Diseases Surveillance Points in Gansu Province]

We have surveyed a population size of 6633315 from Diseases Surveillance Points (DSP) system in Gansu province for the last eleven years. The annual birth rate was 18.20% with an annual standard mortality rate 545.80/10(5). The annual standard mortality for male and female were 607.53/10(5) and 483.29/10(5) respectively. The major causes of death were Respiratory system diseases, Cardiovascular diseases, Neoplasms, Injuries, Digestive system diseases, Pediatric diseases, Infectious diseases in sequence. In eleven years, there seemed to be a rising trend in the mortalities of following diseases as: Cerebrovascular diseases, Ischemic heart diseases, Rheumatic fever and heart disease, Lung Cancer, Liver Cancer, Cancer of the Esophagus, Intestinal cancer, Cervical cancer, Injury, Congenital abnomalities, to different degrees. However, an obvious descending trend on the morbidity and mortality of infectious diseases was moticed. The average life expectancy was 71.05 years in DSP, with male 69.57 years, and female 72.72 years. Diseases with higher PYLL were Injuries, Neoplasms, Respiratory system diseases and the like. Data suggested not only the prevention andcontrol of infectious diseases, but also the surveillance of injuries and the prevention and control of chronic diseases should be strengthened.

Multimodality therapy including surgical resection for limited small cell lung cancer

From 1975 through 1990, 199 patients with limited small cell lung cancer (LSCLC) were subjected to multimodality treatment including surgical resection combined with chemotherapy or chemoradiotherapy in our department. The median postoperative survival time of the 199 patients was 39 months, and the 5-year survival rate was 26%, which was decreased with increase of tumor-stage. In comparison of the survival time of patients in Stage I and those in Stage IIIa, there was a significant difference (P < 0.01). There were no significant differences in survival rate of 3 and 5 years between the patients receiving chemotherapy prior to or after surgical resection. The improvement in survival was documented by surgical resection combined with chemotherapy or chemoradiotherapy for LSCLC. The effect of multimodality treatment is correlated with tumor P-TNM staging, the involvement of lymph node, especially that of the mediastinal lymph node, is a negative factor influencing the prognosis. Surgical resection is an initial management, followed by chemotherapy or chemoradiotherapy may be indicated in LSCLC patients of Stage I, Stage II and some Stage IIIa as the cancer can be resected completely.

[Surgical treatment of 165 cases of stage III small cell lung carcinoma]

The author analysed the effect of surgical therapy in 165 cases with stage III SCLC from 1979 to the end of 1991, and compared with 87 cases of combined therapy and 78 cases in simple operative therapy. The author also makes an observation of cases with pre-operative and (or) post-operative chemo- and radiation therapy. Their over-all 5 year survival rate was 16.6%. Stage among 5 year survival cases in TNM stage. IIIa was 20.4% and no for Stage IIIb. The 5 year survival of combined therapy was 22.8% and that of simple operative group was 7.9%. The result shows that in the Stage III SCLC combined therapy is superior to that of simple operative group. It seems that postoperative radiation and chemotherapy is better than pre-operative in combined therapy group. The author's opinion is that surgical indication of SCLC is limited to stage IIIa.

cAMP-dependent phosphorylation stimulates water permeability of aquaporin-collecting duct water channel protein expressed in Xenopus oocytes

Among water channel proteins (aquaporins), aquaporin-collecting duct (AQP-CD) is the vasopressin-regulated water channel. Vasopressin causes cAMP production in the renal collecting duct cells, and this is believed to lead to exocytic insertion of water channel into the apical membrane (shuttle hypothesis). AQP-CD contains a consensus sequence for cAMP-dependent protein kinase, residues at positions 253-256 (Arg-Arg-Gln-Ser). To determine the role of this site, Ser-256 was substituted for Ala, Leu, Thr, Asp, or Glu by site-directed mutagenesis. In Xenopus oocytes injected with wild-type or mutated AQP-CD cRNAs, osmotic water permeability (Pf) was 4.8-7.7 times higher than Pf of water-injected oocytes. Incubation with cAMP plus forskolin or direct cAMP injection into the oocytes increased Pf of wild-type, but not mutated, AQP-CD-expressing oocytes, whereas the amounts of AQP-CD expression were similar in wild and mutated types as identified by Western blot analysis. In vitro phosphorylation studies of AQP-CD proteins expressed in oocyte showed that cAMP-dependent protein kinase phosphorylated wild-type, but not mutated, AQP-CD proteins. Phosphoamino acid analysis revealed that this phosphorylation occurred at the serine residue. Moreover, phosphorylation of AQP-CD protein in intact rat kidney medulla tissues was stimulated by incubation with cAMP. Our data suggest that cAMP stimulates water permeability of AQP-CD by phosphorylation. This process may contribute to the vasopressin-regulated water permeability of collecting duct in addition to the apical insertion of AQP-CD by exocytosis.

Proximal sequence element-binding transcription factor (PTF) is a multisubunit complex required for transcription of both RNA polymerase II- and RNA polymerase III-dependent small nuclear RNA genes

The proximal sequence element (PSE), found in both RNA polymerase II (Pol II)- and RNA Pol III-transcribed small nuclear RNA (snRNA) genes, is specifically bound by the PSE-binding transcription factor (PTF). We have purified PTF to near homogeneity from HeLa cell extracts by using a combination of conventional and affinity chromatographic methods. Purified PTF is composed of four polypeptides with apparent molecular masses of 180, 55, 45, and 44 kDa. A combination of preparative electrophoretic mobility shift and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses has conclusively identified these four polypeptides as subunits of human PTF, while UV cross-linking experiments demonstrate that the largest subunit of PTF is in close contact with the PSE. The purified PTF activates transcription from promoters of both Pol II- and Pol III-transcribed snRNA genes in a PSE-dependent manner. In addition, we have investigated factor requirements in transcription of Pol III-dependent snRNA genes. We show that in extracts that have been depleted of TATA-binding protein (TBP) and associated factors, recombinant TBP restores transcription from U6 and 7SK promoters but not from the VAI promoter, whereas the highly purified TBP-TBP-associated factor complex TFIIIB restores transcription from the VAI but not the U6 or 7SK promoter. Furthermore, by complementation of heat-treated extracts lacking TFIIIC activity, we show that TFIIIC1 is required for transcription of both the 7SK and VAI genes, whereas TFIIIC2 is required only for transcription of the VAI gene. From these observations, we conclude (i) that PTF and TFIIIC2 function as gene-specific as gene-specific factors for PSE-and B-box-containing Pol III genes, respectively, (ii) that the form of TBP used by class III genes with upstream promoter elements differs from the from used by class III genes with internal promoters, and (iii) that TFIIIC1 is required for both internal and external Pol III promoters.

Karyotypic analysis in the process of immortalization of human cells treated with 4-nitroquinoline 1-oxide

The establishment of a model system of neoplastic transformation of normal human cells has been attempted with a chemical carcinogen, 4-nitroquinoline 1-oxide (4NQO). In the course of these experiments, it was noticed that immortalization of human cells is a multi-step process involving several mutational genetic events. Thus, chromosomal changes which occurred during the process of immortalization of human fibroblasts were examined. To accomplish immortalization, fibroblasts obtained from an embryo were repeatedly treated with 10(-6) M 4NQO from primary culture to passage 51 (59 treatments in total). Before immortalization, some chromosomes (especially, chromosomes 2, 6, 8, 10, 11, 12, 15, 19, and 20), were lost at a relatively high frequency. After immortalization, the chromosomes distributed so broadly in the triploid to hypotetraploid region without a distinct modal number or without marker chromosomes that it was difficult to identify the specific chromosomes related to the immortalization of human cells. No specific structural chromosomal changes were detected. Although the significance of such chromosome changes in relation to immortalization is not clear, the loss of some specific chromosomes suggests that genes which are involved in cellular aging and which suppress immortalization may have been lost in the immortalization process.

Effects of Buthus martensii Karsch scorpion venom on the release of noradrenaline from in vitro and in vivo rat preparations

The aim of this study was to test the neuronal effects of the Chinese Buthus martensii Karsch (BMK) scorpion venom in vivo and in vitro in order to understand the mechanism involved in the cardiovascular pressor effect of this venom. In conscious unrestrained rats, administration of 100 micrograms/kg i.v. BMK venom induced an increase in blood pressure, which was associated with a significant increase in plasma noradrenaline. In isolated atria, BMK also induced an increase in the stimulation-induced release of [3H]noradrenaline in a dose-dependent manner. The modulatory effect of agents acting at sympathetic prejunctional adrenoceptors on [3H]noradrenaline release was not altered by BMK venom administration. Finally, it was observed that 100 micrograms/mL BMK venom increased the intracellular calcium concentration in acutely dissociated sympathetic neurons from adult rat superior cervical ganglion. This action appeared to be mainly due to an influx of extracellular calcium. BMK venom induced a small rise in intracellular calcium in the absence of external calcium, indicating that it may also mobilize calcium from intracellular stores. The results observed in this study suggest that BMK venom may induce pressor responses by releasing noradrenaline from the sympathetic nerve terminals and that activation of neuronal calcium channels may be involved in that process.

Cardiovascular effects of Buthus martensii (Karsch) scorpion venom

Buthus martensii (Karsch) (BMK) scorpion envenomation is a common medical problem in China and BMK scorpion has been widely used in traditional Chinese medicine. However, the cardiovascular effects of this venom have not been systematically investigated. In the present study, i.v. BMK venom injection significantly increased the blood pressure in conscious rats in a concentration-dependent manner (ED50 = 59 +/- 12 micrograms/kg). The increase in blood pressure occurred within 1 min of injection of the venom and was sustained for more than 50 min. Heart rate was not changed by the venom in conscious rats. In vitro studies with BMK venom revealed the increase in the force of contraction, without modification of the contraction frequency (within 20 min) of isolated atrial strips. Contractions of isolated arterial strips from aorta, renal and vertebral arteries were also enhanced by BMK venom with a time lag of 8 min between the application of the venom and the initiation of the contraction. Furthermore, BMK venom-induced rises in blood pressure in vivo and increased contraction of isolated vessel strips were inhibited by prazosin and tolazoline, respectively, two alpha 1-adrenergic antagonists. BMK venom alone did not alter intracellular calcium concentrations, [Ca2+]i, in cultured vascular smooth muscle cells and endothelial cells. However, BMK venom significantly increased the metabolism of InsP3 in dispersed cardiac myocytes, indicating a direct effect on cardiac myocytes. These results demonstrate the significant cardiovascular effects of BMK venom, which may be mediated by an alteration in InsP3 in cardiac myocytes but not by [Ca2+]i in vascular smooth muscle cells.

Neoplastic transformation and characterization of human fibroblasts by treatment with 60Co gamma rays and the human c-Ha-ras oncogene

Human fibroblasts (KMST-6) immortalized by treatment with 60Co gamma rays were further neoplastically transformed by transfection of the c-Ha-ras oncogene from human lung cancer. The ras-transfected cells formed undifferentiated fibrosarcoma in nude mice. One of the tumors was recultured and a neoplastic human fibroblast line, KMST-6/RAS, was established. To analyze multistep carcinogenesis of human cells, the cellular characteristics of these genetically matched immortalized (KMST-6) and neoplastic (KMST-6/RAS) cell lines were studied in detail. KMST-6/RAS cells showed an increased saturation density, colony formation on confluent monolayers of normal human fibroblasts, proliferation in neomycin-containing medium, anchorage-independent growth, and enhanced expression of the transfected c-Ha-ras oncogene, whereas the immortalized cells did not demonstrate these characteristics. Unexpectedly, growth of KMST-6/RAS cells was serum-dependent, although they were neoplastic. Interestingly, the neoplastic cells did not show the criss-crossing or piling up growth pattern characteristic of transformed rodent fibroblasts.

Construction of a retrotransposition indicator sequence using a neomycin resistance-encoding gene containing a functional intron

An intron from a Syrian hamster gene was inserted into a neo gene such that splicing of the neo gene mRNA results in the synthesis of active aminoglycoside phosphotransferase. The unspliced construct is inactive in Escherichia coli, but confers resistance to G418 when transfected into mouse and hamster cells. This selectable marker is designed to aid in the cloning and identification of genomic integration sites following retrotransposition.

Immortalization of epithelial-like cells from human liver tissue with SV40 T-antigen gene

The cells derived from the human embryo liver tissue were transfected with a plasmid pSV3neo containing both the large and small T-antigen gene of the early region of simian virus 40 (SV40), and two cell strains, OUMS-21 and -22, were obtained. OUMS-22 cells, to date, have reached over 100 population doublings through a culture crisis and are considered to have become an immortal cell line. However, OUMS-21 cells failed to become an immortal cell line. Both OUMS-21 and -22 cells were SV40 T-antigen-positive, epithelial-like, and immunoreactive against an anti-keratin 18 monoclonal antibody but against neither an anti-vimentin nor an anti-von Willebrandt factor VIII monoclonal antibody. The staining pattern of cytokeratin in these cells was similar to that in the differentiated human hepatoblastoma and hepatocellular carcinoma cell lines but not to that in the human cholangiocellular carcinoma cell lines. OUMS-21 and -22 cells expressed neither alpha-fetoprotein nor albumin mRNAs. These cells showed no tyrosine aminotransferase activity. However, both OUMS-21 and -22 cells were sensitive to cytotoxicity of aflatoxin B1, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole, and benzo[a]pyrene, whereas human embryo lung fibroblasts were insensitive to the cytotoxicity of these carcinogens. These findings suggest that OUMS-21 and -22 cells may arise from undifferentiated liver stem cells or from hepatocytes that lost their ability to express the liver-specific functions prior to immortalization. Both OUMS-21 and -22 cells expressed glutathione S-transferase pi (GST-pi) mRNA. The expression of GST-pi mRNA highly increased in OUMS-22 cells with their immortalization. Karyotypic analysis showed that numerical and structural aberrations of the chromosomes were profound, but neither specific events nor marker chromosomes were found in OUMS-21 and -22 cells. Both OUMS-21 and -22 cells could grow in soft agar, but they were not tumorigenic when transplanted into nude mice.

Immortalization of normal human fibroblasts by treatment with 4-nitroquinoline 1-oxide

Normal human fibroblasts (the OUMS-24 strain), derived from a 6-week-old human embryo, were transformed (into the OUMS-24F line) and immortalized by repeated treatments (59 times) with 4-nitroquinoline 1-oxide (4NQO). Treatment began during primary culture and ended at the 51st population doubling level (PDL). At the 57th PDL (146 days after the last treatment), morphologically altered, epithelial-type cells appeared, began to grow and became immortal (now past the 100th PDL). However, the control fibroblasts, which were not treated with 4NQO, senesced at the 62nd PDL. The finding that extensive, repeated treatments with 4NQO are required for the immortalization of normal human cells, indicates that multiple mutational events are involved in the immortalization of human cells in general. In other words, immortalization itself seems to be a multi-step process. Karyotypic analysis showed that many cells were hypodiploid before immortalization, but that afterwards chromosomes were distributed broadly in the diploid to tetraploid regions. The immortalized cells showed amplification and enhanced expression of c-myc. Two-dimensional electrophoretic analysis showed that the number of disappearing cellular proteins was greater than the number of the newly appearing ones after the cells became immortalized. Since the immortalized cells showed neither anchorage-independent growth nor tumorigenicity, they are useful for studying factors that can contribute to multi-step carcinogenesis in human cells. In addition, genetically matched normal (OUMS-24) and immortalized (OUMS-24F) cells will be useful for analyzing the genes related to cellular mortality and immortalization.

Antiproliferative effects of suramin on human cancer cells in vitro and in vivo

The present experiment was undertaken to study what types of human cancers are responsive to the antiproliferative effects of suramin. The human malignant cells used were as follows: cervical cancer (HeLa), mammary cancer (MCF-7), bladder cancer (EJ), hepatoma (HuH-7, PLC/PRF/5), embryonal carcinoma (PA-1), in vitro transformed fibroblasts (KMST-6, SUSM-1, VA-13), five myeloma cell lines (KMM-1, KMS-5, KMS-11, KMS-12, RPMI 8226), Burkitt's lymphoma (Raji), acute promyelocytic leukemia (HL-60), chronic myelocytic leukemia (K562), Epstein-Barr virus nuclear antigen positive lymphoblastoid cells (KMS-9). The cells were treated with 25 to 100 micrograms/ml suramin for 72h. Proliferation of HuH-7 and two human myeloma cells (KMS-11 and KMS-12) was remarkably inhibited, and that of PA-1, PLC/PRF/5, KMST-6, two other myeloma cell lines (KMM-1 and KMS-5), Raji and HL-60, was moderately inhibited. In order to confirm part of the results obtained from in vitro experiments, in vivo experiments were also undertaken. The growth of HuH-7 cells transplanted subcutaneously into nude mice was significantly suppressed by intravenous injection of suramin. We discussed the possibility that certain types of human cancers, the growth of which seemed to be more or less dependent on polypeptide growth factors, might be sensitive to the antiproliferative effects of suramin.