[Studies on antiulcer agents. III. Synthesis and antiulcer activity of phenylpropanol derivatives]

It was found that (+/-)ethyl 2-[2-(3-hydroxypropyl)-4-oxocyclohexylidene]-propionate (1), (+/-)ethyl 2-[2-(3-hydroxypropyl)-4,5-dimethoxyphenyl]propionate (2) and (+/-)3-[2-(3-hydroxypropyl)-4,5-dimethoxyphenyl]-2-butanone (3) had excellent antiulcer activities. In order to study structure-activity relationships, (+/-)2-[(3-hydroxypropyl)phenyl]cyclopentanone derivatives (4, 5) and (+/-)2-[(3-hydroxypropyl)phenyl]cyclopentanol derivatives (6, 7) were synthesized and tested for antiulcer activities. As a result, (+/-)2-[2-(3-hydroxypropyl)-4-methoxy-5-(2- piperidinoethoxy)phenyl]cyclopentanone (5k) exhibited potent antiulcer activities.

[Studies on antiulcer agents. IV. Synthesis and antiulcer activity of phenylpropanol derivatives]

It was found that (+/-)ethyl 2-[2-(3-hydroxypropyl)-4-oxocyclohexylidene-propionate (1), (+/-)ethyl 2-[2-(3-hydroxypropyl)-4,5-dimethoxyphenyl]propionate (2), (+/-)3-[2-(3-hydroxypropyl)-4,5-dimethoxyphenyl]-2-butanone (3) and (+/-)2-[2-(3-hydroxypropyl)-4-methoxy-5-(2- piperidinoethoxy)phenyl]cyclopentanone (4) had potent antiulcer activities. In order to study structure-activity relationships, (+/-)3-[(3-hydroxypropyl)phenoxy]-2-butanone derivatives (5, 6) were synthesized and tested for antiulcer activities. Among them, (+/-)3-[2-(3-hydroxypropyl)-4-methoxy-5-[3-(4- methylpiperidino)propoxy]phenoxy]-2-butanone.3/2 oxalate (6k) was selected as a preferred antiulcer agent.

Increased expression of matrix metalloproteinase-II in experimental liver fibrosis in rats

Matrix metalloproteinase-II (MMP-II, 72-kd type IV collagenase, or gelatinase) is one of the gene families of zinc enzymes capable of degrading extracellular matrix molecules, and specifically of degrading type IV and V collagens, gelatin, fibronectin, and elastin. In this study, we used both the liver fibrosis model and the reversibility model of experimental cirrhosis to clarify how MMP-II participates in liver fibrosis of rats. To produce fibrosis model, rats received subcutaneous injections of CCl4 twice weekly for 7, 9, or 14 weeks. For the reversibility model, rats were treated with CCl4 three times a week for 8 weeks and killed at 3, 7, 14, 28, or 42 days after discontinuation of treatment. MMP-II gene expression was studied by Northern hybridization technique, and gelatinase activity of MMP-II was examined by zymography using gelatin substrate. At the same time, an immunohistochemical study using anti-type IV collagen antibody was carried out. In liver fibrosis model, nodule formation was established at 14 weeks. Immunodeposit of type IV collagen was increased in wide fibrous septa and was clearly observed along sinusoidal wall. Gene expression of MMP-II increased up to 7 to 12 times compared with that of controls, with the expression rate being maximum at an intermediate stage of fibrosis. Zymography showed the expressions of both 65-kd latent MMP-II, which is confirmed to be activated by adding p-aminophenylmercuric acetate, and 62-kd active MMP-II during fibrosis. The expression of both forms increased 13 to 28 times as the fibrosis progressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of matrix metalloproteinase 9 (92-kilodalton gelatinase/type IV collagenase = gelatinase B) in osteoclasts: implications for bone resorption

BACKGROUND

Matrix metalloproteinase 9 (MMP-9, 92-kD gelatinase/type IV collagenase = gelatinase B) is a member of the MMP gene family and implicated in tissue destruction in the various pathophysiologic conditions. Our previous study showed that MMP-9 purified from human fibrosarcoma cells can cleave the cross-link-containing NH(2)-terminal telopeptides of the alpha 2 chain of type I collagen and collagen types III, IV, and V as well as gelatins.

EXPERIMENTAL DESIGN

To investigate the role of MMP-9 in bone resorption we have examined its localization in the human bone tissues by immunohistochemistry and in situ hybridization. The enzymic properties were also biochemically studied.

RESULTS

Immunohistochemistry using monoclonal antibodies against MMP-1 (interstitial collagenase), MMP-2 (72-kD gelatinase/type IV collagenase = gelatinase A), MMP-3 (stromelysin-1), MMP-9, and tissue inhibitor of metalloproteinases-1 demonstrated that MMP-9 is localized exclusively in osteoclasts of the bone tissues from normal subjects and patients with rheumatoid arthritis or metastatic carcinoma whereas some osteoclasts are also labeled by anti-(MMP-1) antibody. Northern blot and in situ hybridizations of rheumatoid bone tissues using a RNA probe for MMP-9 exhibited strong signals for the mRNA within osteoclasts. MMP-9 depolymerized acid-insoluble polymers of type I collagen and digested collagen fibrils in the demineralized bone. The gelatinolytic activity of the proteinase was optimal at pH 7.5, but 50 to 80% of the full activity was retained at pH 5.5 to 6.0. It was also 90% active in the presence of 100 mM Ca2+. Degradation of acid-soluble and -insoluble type I collagens by MMP-9 was enhanced at higher concentrations of Ca2+. The zymogen of MMP-9 was activated up to approximately 85% of full activity by incubation at pH 2.3.

CONCLUSIONS

These results demonstrate that MMP-9 is produced by osteoclasts in the human bone tissues and suggest that it can degrade bone collagens in concert with MMP-1 and cysteine proteinases in the subosteoclastic microenvironment. This proteinase may play a role in the normal bone remodeling and pathologic bone resorption in the human diseases.

Induction of M(r) 92,000 type IV collagenase expression in a squamous cell carcinoma cell line by fibroblasts

A previous investigation (Matsumoto et al., J. Oral Pathol. Med., 18: 498-501, 1989) has shown that the in vitro invasion of a collagen gel by squamous cell carcinoma can be substantially augmented in the presence of fibroblasts. Therefore, we undertook a study to determine if the production of collagenase(s) by a squamous cell carcinoma cell line, UM-SCC-1, was up-regulated by fibroblasts. Cocultivation of UM-SCC-1 cells with MDA-TU-138 fibroblasts, both established from the oral cavity, resulted in a dose-dependent increase in the activity of a M(r) 92,000 gelatinase as shown by zymography. Augmented M(r) 92,000 gelatinase activity was a consequence of the stimulation of the UM-SCC-1 cells by a soluble, fibroblast-derived factor since this effect could be reproduced with fibroblast-conditioned medium but not with glutaraldehyde-fixed fibroblasts. The increased M(r) 92,000 gelatinolytic activity could be accounted for by an increase in M(r) 92,000 type IV collagenase (MMP-9) protein, as demonstrated by Western blotting for this metalloproteinase. Trypsin treatment of the fibroblast-conditioned medium abolished its ability to increase MMP-9 secretion by UM-SCC-1 cells. Furthermore, fractionation of the fibroblast-conditioned medium revealed a M(r) 3,000-10,000 soluble factor(s) which was responsible for the augmented production of MMP-9 by UM-SCC-1 cells. To determine if the increased production of MMP-9, in response to the fibroblasts, was a consequence of increased promoter activity, UM-SCC-1 cells were transiently transfected with a chloramphenicol acetyltransferase reporter driven by the MMP-9 promoter and plated on plastic or on a monolayer of MDA-TU-138 fibroblasts. A 4-5-fold stimulation of MMP-9 promoter activity was observed with UM-SCC-1 cells plated with the MDA-TU-138 fibroblasts, when compared with similarly transfected cells recultured on plastic. In conclusion, we have demonstrated that MMP-9 expression in a squamous cell carcinoma cell line is augmented by a fibroblast-derived protein(s). This finding indicates a role for stromal cells in the regulation of MMP-9 expression in squamous cell carcinoma. The ability of fibroblasts to regulate MMP-9 expression in tumor cells in vitro may explain the observation that the amount of M(r) 92,000 type IV collagenase mRNA in tumor cells is highest at the tumor:stromal interface of resected squamous cell carcinoma.

The C-terminal region of membrane type matrix metalloproteinase is a functional transmembrane domain required for pro-gelatinase A activation

We identified a new matrix metalloproteinase (membrane type matrix metalloproteinase (MT-MMP)) that has a potential transmembrane (TM) domain at the C terminus and reported its expression on the surface of invasive tumor cells. The expression of MT-MMP induced specific activation of 72-kDa pro-gelatinase A (Sato, H., Takino, T., Okada, Y., Cao, J., Shinagawa, A., Yamamoto, E., and Seiki, M. (1994) Nature 370, 61-65). Thus, MT-MMP on the cell surface is thought to play an important role in various physiological and pathological processes accompanying tissue remodeling. In this study, we demonstrated that the potential TM domain deduced from the amino acid sequence functions as a membrane linker when it is fused to a secretory protein, tissue inhibitor of matrix metalloproteinases-1. The pro-gelatinase A activation function of MT-MMP was abolished by truncation of the TM domain and recovered by fusing the MT-MMP mutant with the TM domain of interleukin 2 receptor alpha-chain. The truncated MT-MMP was released from the cells into the medium and detected as processed or modified forms. In spite of the deletion of the TM domain some portions of the mutant MT-MMP were still retained on the surface of cells. Thus, MT-MMP has an additional device to keep it on the cell surface. The TM domain however, plays an essential role in the pro-gelatinase A activation function of MT-MMP, probably regulating its fine orientation or the localization that is necessary to interact with substrate.

c-Jun, c-Fos and their family members activate the transcription mediated by three 21-bp repetitive sequences in the HTLV-I long terminal repeat

Transcription of human T-cell leukemia virus type I is regulated by a viral transactivatior Tax, through the 21-bp sequence in the long terminal repeat (LTR). We found that cellular transcription factor AP-1 (c-Jun/c-Fos heterocomplex) bound to the 21-bp sequence. The binding affinity of the complex increased in proportion to the number of the 21-bp sequence, and the transcriptional activation by AP-1 became evident only when the reporters had more than three 21-bp sequences. Thus, AP-1 may play a role in the viral transcription from the LTR with three 21-bp sequences in the absence of Tax, such as in the early stage of the virus infection.

[Studies on antiulcer agents. I. The effects of various methanol and aqueous extracts of crude drugs on antiulcer activity]

The antiulcer activities of 59 methanol and aqueous extracts obtained from 59 crude drugs on the ethanol-HCl-induced ulceration in rats were investigated. Among them 15 extracts were selected and they were further examined for their effects on indomethacin-, aspirin- and the water-immersion stress-induced ulcer. From these results, the methanol extract of root of Iris germanica was found to, show potent antiulcer activities. The above methanol extract was separated into 3 portions by solvent extraction, and the ether soluble portion was fractionated into 5 fractions (1 to 5) by chromatography. Fractions 4 and 5 showed significant antiulcer activities. Fraction 4 was further purified and the obtained gamma-irigermanal exhibited a potent antiulcer activity. However, further investigations are required to understand the mechanism.

[Studies on antiulcer agents. II. Synthesis and antiulcer activity of phenylpropanol derivatives]

It was found that gamma-irigermanal, obtained from the methanol extract of root of Iris germanica, exhibited a potent antiulcer activity. Therefore, this compound was selected as a lead-compound, and related compounds were synthesized and tested for antiulcer activities. It was found that (+/-) ethyl 2-[2-(3-hydroxypropyl)-4-oxocyclohexylidene]- propionate (1) had excellent antiulcer activities. Then phenylpropanol derivatives, obtained by changing from cyclohexane ring of 1 to benzene ring, were synthesized and tested for antiulcer activities in order to study structure activity relationships. As a result, (+/-) ethyl 2-[2-(3-hydroxypropyl)-4,5-dimethoxy-phenyl]propionate (2b) and (+/-) 3-[2-(3-hydroxypropyl)-4,5-dimethoxyphenyl]-2-butanone (5) were shown to have antiulcer activities.

Serum response factor has functional roles both in indirect binding to the CArG box and in the transcriptional activation function of human T-cell leukemia virus type I Tax

We previously reported that Tax1 of human T-cell leukemia virus type I interacts directly with serum response factor (SRF) and that Tax1 activates the transcription of several cellular immediate-early genes through the SRF binding site (CArG box). This activation required the transcriptional activation function of Tax1, identified as an activity of GALTax (a chimeric Tax1 with the yeast transcription factor GAL4) at the GAL4-binding site. In this study, we examined whether SRF plays a role in the transcriptional activation function of Tax1. Expression of Tax1 suppressed the GALTax activity at the GAL4 site as a result of squelching, and the suppressed activity was recovered by the overexpression of SRF, suggesting that SRF is a factor that is required for GALTax activity and that is inhibited by competition with Tax1. The expression of antisense SRF RNA specifically inhibited GALTax activity to less than 20%. Deletion of the Tax1 interaction domain of SRF at its C terminus converted SRF from an activator of GALTax to an inhibitor. These results suggest that SRF is an essential component of the transcriptional activation of Tax1 in addition to a mediator of CArG box binding.

A matrix metalloproteinase expressed on the surface of invasive tumour cells

Gelatinase A (type-IV collagenase; M(r) 72,000) is produced by tumour stroma cells and is believed to be crucial for their invasion and metastasis, acting by degrading extracellular matrix macro-molecules such as type IV collagen. An inactive precursor of gelatinase A (pro-gelatinase A) is secreted and activated in invasive tumour tissue as a result of proteolysis which is mediated by a fraction of tumour cell membrane that is sensitive to metalloproteinase inhibitors. Here we report the cloning of the complementary DNA encoding a new matrix metalloproteinase with a potential transmembrane domain. Expression of the gene product on the cell surface induces specific activation of pro-gelatinase A in vitro and enhances cellular invasion of the reconstituted basement membrane. Tumour cells of invasive lung carcinomas, which contain activated forms of gelatinase A, were found to express the transcript and the gene product. The new metalloproteinase may thus trigger invasion by tumour cells by activating pro-gelatinase A on the tumour cell surface.

Expression of 72 kDa type IV collagenase and invasion activity of human glioma cells

Metalloproteinases, inhibitors of metalloproteinases, plasminogen activators, inhibitors of plasminogen activators and cathepsins are thought to be involved in invasion by tumor cells. Glioblastoma multiforme is highly malignant and extremely refractory to therapy. One reason is because of its highly invasive nature within the nervous system. However, it remains unclear how invasion/dissemination of glioblastoma multiforme proceeds. In this study, we attempted to determine which proteinases were responsible for the invasion activity of human glioma cell lines in vitro. Nine human glioma cell lines (NHG1, NHG2, IN157, IN301, IN500, U251, U343, T98G and CCF-STTG1) derived from patients with glioma were grown in culture and used. We compared the invasion activity of glioma cell lines in a Matrigel invasion assay system, and formulated the activity as invasion index (%). Among the nine cell lines, IN157, IN500 and U343 showed less than 10% invasion activity (low group); NHGI, IN301 and CCF-STTG1 showed 10-25% activity (intermediate group); NHG2, U251 and T98G showed more than 30% activity (high group). Addition of an inhibitor of metalloproteinases, TIMP-1, to the assay system was found to significantly inhibit invasion activity of T98G cells (P < 0.01). Northern blot analysis demonstrated expression of urokinase-type plasminogen activator (uPA), tissue-type PA (tPA) and PA inhibitor-1 (PAI-1) in some of the above cell lines. Cellular levels of PAs and their inhibitor mRNA, however, appeared not to be correlated with invasion activity in most glioma cell lines except for CCF-STTG1. Expression of 72 kDa type IV collagenase (MMP-2) was much lower in IN157, IN500 and U343 than other cell lines, whereas expression of TIMP-1 was much higher in IN500 than in other cell lines. Zymographic activity was found to be comparable to MMP-2 mRNA levels in all cell lines except for CCF-STTG1. Type IV collagenolytic activity was also comparable to invasion activity in nine cell lines. These observations suggest the role of type IV collagenase and its inhibitors in determining capacity for invasion by human gliomas. However, a comprehensive analysis both in vitro and in vivo is required to confirm the role for this enzyme in glioma cell invasiveness.

Tax proteins of human T-cell leukemia virus type 1 and 2 induce expression of the gene encoding erythroid-potentiating activity (tissue inhibitor of metalloproteinases-1, TIMP-1)

A growth factor-like activity for erythroid cells (erythroid-potentiating activity) is produced by the T-cells infected with human T-cell leukemia virus type 2 (HTLV-2) (Gasson, J. C., Golde, D. W., Kaufman, S. E., Westbrook, C. A., Hewick, R. M., Kaufmann, R. J., Wong, G. G., Temple, P. A., Leary, A. C., Brown, E. L., Orr, E. C., and Clark, S. C. (1985) Nature 315, 768-771) and is reportedly identical with tissue inhibitors of matrix metalloproteinases-1 (TIMP-1) (Docherty, A. J. P., Lyons, A., Smith, B. J., Wright, E. M., Stephens, P. E., Harris, T. J. R., Murphy, G., and Reynolds, J. J. (1985) Nature 318, 66-69). We found that adult T-cell leukemia cell lines infected with HTLV-1 also express high levels of a TIMP-1 transcript. A viral transactivator of HTLV-1, Tax1, in a human T-cell line (Jurkat), was sufficient to stimulate transcription of the TIMP-1 gene. Deletion and mutation analysis of the TIMP-1 gene promoter showed that the AP-1 binding site in the 38-base pair sequence conserved between the human and mouse genes was essential for activation by Tax1. The transactivator of HTLV-2 also stimulated the promoter through the same cis-element. The reported growth-promoting activity of TIMP-1 against erythroid cells and potentially against HTLV-1-infected T-cells may modulate the clinical course of adult T-cell leukemia.

Expression of type-IV collagenases in human tumor cell lines that can form liver colonies in chick embryos

Chick embryo has been used as a model system for evaluating the metastatic potential of tumor cells. We have previously demonstrated that expression of the tissue inhibitor of matrix metalloproteinase-I (TIMP-I) gene can suppress liver colonization of tumor cels in chick embryo, probably by inhibiting the activity of matrix metalloproteinases (MMP) produced by tumor cells. In an attempt to identify MMP associated with liver colonization, we examined 24 human tumor cell lines for their potential to form metastatic colonies in chick-embryo liver after the cells had been inoculated into the chorioallantoic membrane (CAM) vein. We compared the results with the mRNA expression of MMP (MMP-I, MMP-2, MMP-3, MMP-9) studied previously. Three of 8 cell lines from mesenchymal tumors (fibrosarcoma HT1080, osteosarcomas SK-ES and MNNG/HOS) and 2 of 16 cell lines from epithelial tumors (gastric carcinoma KKLS and bladder carcinoma T24) proliferated in the livers. MMP-2 and MMP-9 were the enzymes whose transcripts were more frequently expressed in these 5 metastatic cell lines (MMP-1; 2/5, MMP-2; 4/5, MMP-3; 0/5, MMP-9; 3/5), but other cell lines that did not form liver colonies expressed the transcripts at lower frequency (MMP-2; 7/19, MMP-9; 3/19). Although either or both MMP-2 and MMP-9 transcripts were expressed in 4 of the 5 metastatic cell lines, they were undetectable in T24 cells. However, induced expression of both enzymes was detected by immunostaining in the T24 cells colonized in the liver. Thus, type-IV collagenases expressed by tumor cells may play a role in facilitating colonization in chick embryos.

Two distinct regions form a functional activation domain of the HTLV-1 trans-activator Tax1

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) is an enigmatic viral transactivator that regulates expression of the viral gene and also several cellular genes normally controlled by various mitogenic signals. However, previous studies have failed to define the functional domains of Tax1 for enhancer specificities and for transcriptional activation (95% of the protein portion was indispensable for the activation function). This complexity has hampered understanding of the molecular basis of Tax1 action. In this study, we analysed the activation function of a Tax1 fused to the heterologous DNA-binding domain of the yeast transcription factor GAL4 and dissected the domain required for the activation function by using derivatives of a Tax1 mutant with an insertion between amino acids (a.a.) 170 and 171. Analysis of the derivatives of the mutant fusion protein having various partial overlaps encompassing the interrupted site suggested that two contiguous stretches, AD-I (2-255 a.a.) and AD-II (227-337 a.a.), should be both intact for the activation function of Tax1 and that they form a functional activation domain.

Epstein-Barr virus lytic cycle spreads via cell fusion in a nasopharyngeal carcinoma hybrid cell line

NPC-KT cl.S61, a subclone derived from an epithelial-nasopharyngeal carcinoma hybrid cell line NPC-KT, showed extensive Epstein-Barr virus (EBV) production and cell fusion when the EBV replicative cycle was induced by 5-iodo-2'-deoxyuridine. On the contrary, parental NPC-KT cells produced virus at a lower level and did not show cell fusion. Cell fusion in cl.S61 cells was blocked by 2-deoxyglucose and acyclovir, inhibitors of glycosylation and EBV DNA polymerase, respectively, with a concomitant decrease in the number of cells expressing EBV growth-associated antigens. However, the frequency of virus antigen expression in parental NPC-KT cells was not significantly affected by these drugs. This result suggests that efficient production of EBV from cl.S61 cells is due to the spreading of viral replicative cycle via cell fusion. It was also demonstrated by in situ autoradiography that cl.S61 cells producing virus fused to not only EBV receptor/CR2 positive Raji and BJAB cells, but also to receptor-negative Jurkat cells. The possible mechanism of EBV entry into cells devoid of virus receptor by cell fusion is discussed.

Human T-cell leukemia virus type 1 Tax activates transcription of the human fra-1 gene through multiple cis elements responsive to transmembrane signals

We have shown that Tax1 of human T-cell leukemia virus type 1 stimulates the expression of several cellular immediate-early genes (M. Fujii, T. Niki, T. Mori, T. Matsuda, M. Matsui, N. Nomura, and M. Seiki, Oncogene 6:1023-1029, 1991). In this study, the 5'-flanking region of the human fra-1 gene, which is a Tax1-inducible fos-related gene, was isolated and Tax1 or serum-responsive cis elements were analyzed to obtain further insight into the mechanism of Tax1 action. The 62-bp sequence starting 46 nucleotides upstream from the translation initiation site showed 71% homology with the sequence surrounding the TATA box of the c-fos promoter. Regulatory motifs identified in the c-fos promoter, such as an Ets-binding site, E boxes, a CArG box, c-fos AP-1 sites, and two retinoblastoma control elements, were also found upstream of the c-fos homology region. A 502-bp fragment containing these motifs mediated transcriptional activation by Tax1 or by serum in a transient transfection assay. Three independent Tax1-responsive regions (TRRs) were identified, and mutations in each revealed that one of the retinoblastoma control elements in TRR1 and the c-fos AP-1 sites in TRR2 and TRR3 were essential for the activation. Although TRR2 contains a CArG box-like sequence, it was a weak binding site for p67SRF, if it bound at all, and was not required for activation. All three TRRs could also mediate the signals stimulated by serum. Thus, Tax1 appears to activate fra-1 gene expression by means of a part of the cellular machinery similar to that which mediates growth signals.

v-Src activates the expression of 92-kDa type IV collagenase gene through the AP-1 site and the GT box homologous to retinoblastoma control elements. A mechanism regulating gene expression independent of that by inflammatory cytokines

The 92-kDa type IV collagenase (matrix metalloproteinase-9; MMP-9) is frequently expressed in cells showing an invasive nature during physiological and pathological processes, and the expression is strictly controlled by a variety of trans-membrane signals. Binding sites for NF-kB, Sp-1, and AP-1 are reportedly required for induction of MMP-9 gene expression by tumor necrosis factor-alpha or 12-O-tetradecanoylphorbol-13-acetate. Comparison of the sequence of the newly cloned mouse MMP-9 promoter region with our previous human isolate revealed that, in addition to the above mentioned elements, four units of GGGG(T/A)GGGG sequence (GT box) were conserved between the two species. In this study, we have demonstrated that one of the GT boxes located downstream of the AP-1 site is essential along with the AP-1 site for the activation of the promoter by v-Src but not by tumor necrosis factor-alpha or 12-O-tetradecanoylphorbol-13-acetate. Gel mobility-shift assays revealed that binding proteins for retinoblastoma control element, including Sp-1 family protein, can bind specifically to GT boxes. Thus, the v-Src signals to the AP-1 site and to the GT box homologous to retinoblastoma control element acted synergistically in transcriptional activation. These results suggest that certain v-Src-mediated signals are propagated along pathways that are independent of inflammatory cytokines.

Tissue inhibitor of metalloproteinase 1 is a negative regulator of the metastatic ability of a human gastric cancer cell line, KKLS, in the chick embryo

Tissue inhibitors of metalloproteinases (TIMPs) are the negative regulators of matrix metalloproteinases that degrade extracellular matrix. We examined the regulatory role of TIMP-1 in the metastatic activity of human gastric cancer cell lines in chick embryos because unregulated matrix metalloproteinase activities are believed to be essential during metastatic processes. One of the nine cell lines examined, KKLS cells, formed metastatic colonies in the chick livers. These cells expressed undetectable levels of TIMP-1, and this was not inducible by 12-O-tetradecanoylphorbol 13-acetate. Derivatives of KKLS cells with different levels of TIMP-1 expression were prepared by transfection of the human TIMP-1 complementary DNA controlled by a simian virus 40 early promoter. Metastatic abilities were suppressed by almost 70% in the transfectants expressing high levels of TIMP-1. In contrast, no suppression was observed in the control transfectants or in cells expressing the transfected TIMP-1 gene at low levels. These data indicate that a reduced expression of TIMP-1 in KKLS cells is responsible for their consequent metastatic potential. Moreover, it suggests that matrix metalloproteinase enzymatic activities are a prerequisite for metastatic activity in this experimental model system.

Regulatory mechanism of 92 kDa type IV collagenase gene expression which is associated with invasiveness of tumor cells

92-kDa Type IV collagenase, a member of matrix metalloproteinases, is believed to play a critical role in physiological tissue-remodeling processes and also in many pathological conditions such as tumor invasion. We analyzed the 5'-flanking sequence of the 92 kDa type IV collagenase gene that controls the expression of the gene by ligating it to the chloramphenicol acetyltransferase gene. Deletion and mutation analysis revealed that three motifs, homologous to the binding sites for AP-1, NF-kappa B, and Sp-1 proteins, contributed positively to induction by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and tumor necrosis factor alpha (TNF alpha). The AP-1 site was indispensable but not sufficient for the induction and required synergistic cooperation with either the kappa B or the Sp-1 site. In OST cells, a nuclear factor which bound to Sp-1 was constitutively expressed, and those bound to AP-1 and kappa B elements were rapidly induced by TNF alpha treatment. Comparison of the findings with those for the promoters of other TPA-inducible matrix metalloproteinases, interstitial collagenase and stromelysin 1, revealed that the signal to the AP-1 sites is common for the TPA-inducibility of the genes but that the signals to the kappa B or Sp-1 sites, which are not present in interstitial collagenase and stromelysin 1 promoters, are the unique determinant for the inducibility of the 92 kDa type IV collagenase gene.

[Expression of matrix metalloproteinases in tumor cells]

Tumor cells have to degrade extracellular matrix components to invade surrounding tissue and to form metastatic colonies at distant organs. Matrix metalloproteinases are the enzymes that can degrade various types of native collagens and glycoproteins. In this study, we demonstrated the roles of matrix metalloproteinases in metastatic colony formation in chick embryo by transfecting TIMP-1 gene into a metastatic gastric cancer cell line, KKLS. The mechanism regulating expression of one of the type IV collagenases, MMP-9, was also studied using the promoter region of the gene.

Gastroprokinetic activity of nizatidine, a new H2-receptor antagonist, and its possible mechanism of action in dogs and rats

We studied the anti-acetylcholinesterase (AChE) activity of a new H2-antagonist, nizatidine, in in vitro experiments and its gastroprokinetic action in the dog and rat in comparison with other H2-antagonists, neostigmine and cisapride. The IC50 of nizatidine for AChE was 6.7 x 10(-6) M, and this activity was reversible. The relative anti-AChE potency was in the following order: neostigmine > nizatidine > cimetidine >> famotidine. The inhibition of AChE by nizatidine was noncompetitive, with a Ki value of 7.4 x 10(-6) M. Gastrointestinal (GI) motility was examined during the interdigestive state in dogs with chronically implanted force transducers. Nizatidine (0.3-3 mg/kg, i.v.) significantly increased the motor index in a dose-dependent manner. It was of interest that the contractile response of the GI tract to nizatidine was similar to the interdigestive migrating contractions-like activity. At the doses used in this study, neither cimetidine nor famotidine had a significant effect on the motor index. Neostigmine at a higher dose of 0.06 mg/kg and cisapride at 0.3 mg/kg were found to stimulate GI contractions. Gastric emptying was determined in rats given phenol red as a liquid test meal. Nizatidine (3 mg/kg, i.p., or above) significantly increased gastric emptying, whereas the other H2-antagonists had no such effect. The ED50 and ED90 values of nizatidine for inhibition of gastric acid secretion were 0.18 and 3.22 mg/kg in dogs, and 2.94 and 19.6 mg/kg in rats, respectively. These findings suggest that nizatidine stimulates GI contractions and accelerates gastric emptying at gastric antisecretory doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of HTLV-1 Tax1 with p67SRF causes the aberrant induction of cellular immediate early genes through CArG boxes

Tax1 of human T-cell leukemia virus type 1 (HTLV-1) is a transcriptional activator for viral gene expression and is also a transforming protein through inducing the expression of several cellular genes under the control of mitogenic signals. We identified the CArG boxes as a Tax1-responsive cis-acting element for the cellular immediate early genes c-fos, egr-1, and egr-2. Using a chimeric protein consisting of the CArG-binding factor p67SRF and the heterologous DNA-binding domain of a yeast transcription factor GAL4, we demonstrated that Tax1 activates the transcriptional activity of p67SRF through the GAL4-binding site. The carboxy-terminal half of p67SRF, which lacks domains for DNA-binding, dimerization, and ternary complex formation with p62TCF, was sufficient for the activation by Tax1. Tax1 produced in Escherichia coli bound p67SRF in vitro. The complex formation in vivo was also indicated by the finding that the acidic activation domain of VP16, by fusion to p67SRF, can complement the transcriptional activation function of a mutant Tax1 in trans. Thus, Tax1 activates CArG-mediated transcription without mitogenic signals through interaction with a CArG-binding factor, p67SRF. This must be one of the primary steps by which Tax1 causes aberration in growth control of the infected cells.

Epstein-Barr virus BZLF1 transactivator is a negative regulator of Jun

The Epstein-Barr virus BZLF1 protein that can induce the lytic cycle in latently infected cells is a transcription factor partially homologous to Fos and binds not only the canonical TPA (tetradecanoyl phorbol acetate)-responsive element (TRE) site but also sequences deviating from the TRE consensus sequence. Thus, expression of cellular genes regulated by AP-1, including the autoregulated AP-1 family, should be affected by BZLF1. However, induction of only Fos by BZLF1 was observed in a gel mobility shift assay using an oligonucleotide probe containing the TRE sequence and the antibody against Fos protein. The c-jun promoter, which contains a binding site for Jun and BZLF1, was stimulated by Jun but not by BZLF1. Furthermore, BZLF1 inhibited stimulation of the c-jun promoter by Jun. Jun together with Fos effectively activated the collagenase promoter that contains a single TRE site. However, not only was BZLF1 unable to stimulate the collagenase promoter, but it also inhibited activation by Jun and Fos. On the other hand, BZLF1 stimulated constructs containing multimeric binding sites. These results and those of previous studies of Epstein-Barr virus promoters regulated by BZLF1 indicate that BZLF1 requires adjacent multiple DNA-binding sites for cooperative interaction to function as a transactivator and to repress the activation by Jun of promoters containing a single TRE site. This suggests that BZLF1 evolved to confer distinct regulatory patterns upon viral target genes and cellular AP-1-responsive genes.