IDH1 and IDH2 mutation studies in 1473 patients with chronic-, fibrotic- or blast-phase essential thrombocythemia, polycythemia vera or myelofibrosis

In a multi-institutional collaborative project, 1473 patients with myeloproliferative neoplasms (MPN) were screened for isocitrate dehydrogenase 1 (IDH1)/IDH2 mutations: 594 essential thrombocythemia (ET), 421 polycythemia vera (PV), 312 primary myelofibrosis (PMF), 95 post-PV/ET MF and 51 blast-phase MPN. A total of 38 IDH mutations (18 IDH1-R132, 19 IDH2-R140 and 1 IDH2-R172) were detected: 5 (0.8%) ET, 8 (1.9%) PV, 13 (4.2%) PMF, 1 (1%) post-PV/ET MF and 11 (21.6%) blast-phase MPN (P<0.01). Mutant IDH was documented in the presence or absence of JAK2, MPL and TET2 mutations, with similar mutational frequencies. However, IDH-mutated patients were more likely to be nullizygous for JAK2 46/1 haplotype, especially in PMF (P=0.04), and less likely to display complex karyotype, in blast-phase disease (P<0.01). In chronic-phase PMF, JAK2 46/1 haplotype nullizygosity (P<0.01; hazard ratio (HR) 2.9, 95% confidence interval (CI) 1.7-5.2), but not IDH mutational status (P=0.55; HR 1.3, 95% CI 0.5-3.4), had an adverse effect on survival. This was confirmed by multivariable analysis. In contrast, in both blast-phase PMF (P=0.04) and blast-phase MPN (P=0.01), the presence of an IDH mutation predicted worse survival. The current study clarifies disease- and stage-specific IDH mutation incidence and prognostic relevance in MPN and provides additional evidence for the biological effect of distinct JAK2 haplotypes.

IDH1 and IDH2 mutation analysis in chronic- and blast-phase myeloproliferative neoplasms

Bone marrow DNA was screened for isocitrate dehydrogenase (IDH) mutations in 200 patients with chronic (n=166) or blast (n=34) phase myeloproliferative neoplasms (MPN). Included among the former were 77 patients with primary myelofibrosis (PMF), 47 essential thrombocythemia and 38 polycythemia vera (PV). Nine IDH mutations (5 IDH1 and 4 IDH2) were detected; mutational frequencies were approximately 21% (7 of 34) for blast-phase MPN and approximately 4% (3 of 77) for PMF. IDH mutations were seen in only 1 of 12 paired chronic-blast-phase samples and in none of 27 concurrently studied acute myeloid leukemia (AML) patients without antecedent MPN. IDH1 mutations included R132C (n=4; two post-PMF AML, one post-PV AML and one PMF) and R132S (n=1; post-PMF AML). IDH2 mutations included R140Q (n=3; one post-PMF AML, one post-PV AML and one PMF) and a novel R140W (n=1; mutation found in both chronic- and blast-phase samples). The entire study cohort was also screened for JAK2 and MPL mutations and JAK2V617F was found in three IDH-mutated cases (two PMF and one PV). This study shows a relatively high incidence of IDH mutations in blast-phase MPN, regardless of JAK2 mutational status, and the occurrence of similar mutations in chronic-phase PMF.

Enhanced production of matrix metalloproteinases and activation of matrix metalloproteinase 2 (gelatinase A) in human gastric carcinomas

We examined the production and tissue localization of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in gastric carcinoma tissues. MMP-1 (tissue collagenase), MMP-9 (gelatinase B) and TIMP-2 were immunolocalized in carcinoma cells and MMP-2 (gelatinase A) on tumor cell membranes, whereas no or little immunostaining for MMP-3 (stromelysin-1) and TIMP-1 was seen in carcinoma cells. Stromal cells in carcinoma tissue were also positively stained for these MMPs and TIMPs. MMP-2 immunostaining was observed exclusively on advanced gastric carcinoma cells and correlated with vascular invasion by tumor cells. Sandwich enzyme immunoassays revealed enhanced production of MMP-1, MMP-2, MMP-3, MMP-9 and TIMP-1 by carcinoma tissues. Gelatinolytic activities were significantly higher in carcinoma samples than in normal controls. Using gelatin zymography, active forms of MMP-2 and MMP-9 were more frequently detected in carcinoma tissue, and the activation rate of the zymogen of MMP-2 (proMMP-2), but not that of proMMP-9, correlated well with degree of local invasion and lymphatic permeation. Our data indicate an enhanced production of 4 MMPs in gastric carcinoma tissue and suggest that activation of pro-MMP-2 may be a key step for spreading of gastric carcinoma cells.

Early interstitial changes in hypertension-induced renal injury

To elucidate the mechanisms of hypertensive renal injury, we investigated the time course and extent of changes in matrix composition, as well as cell proliferation and infiltration in two-kidney, one clip rats. The nonclipped kidneys from hypertensive and sham-operated control rats (n = 5 to 10 in each group) were studied at 7, 14, 21, and 28 days after clipping. Systolic blood pressure was elevated by day 7 (154 +/- 3 versus 111 +/- 4 mm Hg in sham group, P < .001, n = 10 each). Hypertension resulted in an early expansion of the interstitial volume by 37%, whereas hypertensive vascular changes and glomerular injury did not become evident until day 21. Immunofluorescence studies revealed an early interstitial accumulation of collagens I, III, IV, V, VI, and fibronectin by day 7. In contrast, the glomeruli showed a mild to moderate increase in collagens I, III, IV, V, laminin, and fibronectin but not collagen VI later in the established phase of hypertension. Staining for proliferating cell nuclear antigen as a marker of cell replication was increased in tubular epithelial but not interstitial or glomerular cells. A progressive infiltration of macrophages (16 +/- 2 versus 9 +/- 1 ED1+ cells/mm2, P < .05, n = 6) and T lymphocytes (93 +/- 15 versus 74 +/- 7 CD4+ cells/mm2, n = 8) in the cortical interstitium had already occurred by day 7. On the other hand, only macrophages increased in number within the glomeruli. Thus, renovascular hypertension leads to an early tubular cell proliferation, mononuclear cell recruitment, and deposition of matrix proteins primarily within the interstitium. We conclude that the injury producing nephrosclerosis in this model extends far beyond the glomeruli. Both the tubules and the interstitium are actively involved and may be the more important initial sites of injury.

Overexpression of the wild type p73 gene in human bladder cancer

p73, a first p53 relative, was recently identified and shown to be monoallelically expressed in a number of different human tissues. To determine the potential role of this gene in human bladder cancer, we investigated p73 expression levels, allelic expression patterns, and analysed p73 mutations in 23 unselected primary invasive bladder cancers with matched normal tissues and in seven bladder cancer cell lines. In a comparison between normal and tumor tissues using quantitative RT-PCR analysis, we found that p73 was overexpressed in 22/23 bladder cancers, sometimes as great as 20-fold. Allelic expression analysis using a C/T polymorphism in exon 2 and a newly identified T/C polymorphism in exon 5 revealed that p73 was biallelically expressed in both normal bladder and cancer tissues, suggesting that p73 is not imprinted in bladder tissue. Mutation screening of the p73 gene in bladder cancer DNAs using denaturing high-performance liquid chromatography analysis and DNA sequencing revealed no tumor-specific mutations in any coding exons of the p73 gene. These data suggest that the p73 is unlikely to be a tumor suppressor gene, but that overexpression of p73 may contribute to tumorigenesis in bladder cancer.

Monocyte chemoattractant protein-1 and macrophage infiltration in hypertensive kidney injury

BACKGROUND

We investigated whether monocyte chemoattractant protein-1 (MCP-1) is expressed in hypertensive nephrosclerosis, and tested the effect of angiotensin II type 1 receptor blockade on MCP-1 expression and macrophage (MPhi) infiltration.

METHODS

Rats with two-kidney, one-clip (2K1C) hypertension with and without treatment with the angiotensin II type 1 receptor antagonist valsartan (3 mg/kg/day) were studied. In these animals as well as in spontaneously hypertensive rats (SHR), stroke-prone SHR (SHR-SP), hypertensive mRen-2 transgenic rats (TGR), and respective control strains, MCP-1 expression in the kidney was investigated by Northern and Western blots and by immunohistochemistry. Glomerular and interstitial MPhis were counted.

RESULTS

In the nonclipped kidney of 2K1C rats, MCP-1 expression was elevated at 14 and 28 days when significant MPhi infiltration was present. MCP-1 was localized to glomerular endothelial and epithelial cells, interstitial and tubular cells, MPhis, and vascular smooth muscle cells. A similar pattern of MCP-1 staining was present in TGR kidneys, whereas MCP-1 expression was not increased in SHR and SHR-SP. Valsartan reduced but did not normalize blood pressure, blocked the induction of MCP-1 protein in 2K1C kidneys, and decreased interstitial MPhi infiltration significantly.

CONCLUSION

MCP-1 expression is increased in angiotensin II-dependent models of hypertensive nephrosclerosis and is temporally and spatially related to MPhi infiltration. The angiotensin II type 1 receptor mediates the induction of MCP-1.

Expression and tissue localization of matrix metalloproteinase 7 (matrilysin) in human gastric carcinomas. Implications for vessel invasion and metastasis

We examined the production and tissue localization of matrix metalloproteinase-7 (MMP-7 = matrilysin) in human gastric carcinomas and analyzed the data in connection with the clinicopathological factors. Sandwich-enzyme immunoassay for the zymogen of MMP-7 (proMMP-7) showed enhanced production of MMP-7 in carcinoma tissues compared with control normal gastric mucosa. Immunohistochemical studies demonstrated that MMP-7 is localized predominantly to the carcinoma cells in 71% of the carcinoma samples (30/42 cases). The percentage of immunoreactive carcinoma cells to total carcinoma cells (positive ratio) was significantly higher in intestinal-type carcinomas (26%, median) than in diffuse-type carcinomas (3%, median) (p < 0.05). The positive ratio was markedly higher in carcinoma groups with vascular invasion (28%) or lymphatic permeation (12%) than in those without invasion (6%) or permeation (0%) (p < 0.05). It was also significantly higher in carcinoma groups with liver (49%) or lymph-node metastases (15%) than in those without metastases (6 and 2% respectively) (p < 0.05). Both proMMP-7 of 28 kDa and active MMP-7 of 19 kDa were detected in the carcinoma tissues by immunoblotting. Reverse-transcription-PCR showed specific amplification in 50% of the carcinoma cases (6/12 cases) and 8% of the normal control specimens (1/12 cases). In situ hybridization demonstrated that the carcinoma cells almost selectively express MMP-7 mRNA. These data suggest that enhanced production of proMMP-7 and its activation are implicated in invasion and metastasis of human gastric carcinomas.

Superficial-type adenomas and adenocarcinomas of the colon and rectum: a comparative morphological study

BACKGROUND/AIMS

It has been uncertain whether colorectal carcinomas preferentially arise on preexisting adenomas or de novo. However, from a morphological viewpoint, it seems unlikely that pedunculated or exophytic malignant polyps progress to the deeply ulcerated advanced carcinomas usually found clinically.

METHODS

The morphological features of 26 nonpolypoid, superficial-type colorectal tumors (17 adenomas and 9 adenocarcinomas) were compared to clarify the developmental route of colorectal carcinomas.

RESULTS

The adenomas and adenocarcinomas were very similar in size and gross appearance; however, examination of the surface appearances of unsectioned tumors by dissecting microscopy was helpful for distinguishing the two. Histologically, no adenomatous tissue was found in any case of superficial-type adenocarcinoma. Five of the nine adenocarcinomas, even including those of small size, invaded the submucosal layer, and two showed lymph node metastasis.

CONCLUSIONS

These findings suggest that superficial-type adenocarcinomas show rapid growth and aggressive behavior. We suggest that this type of carcinoma may not progress by the adenoma-to-carcinoma pathway but that it may arise from a very small superficial-type adenoma.

Environmental factors as regulators and effectors of multistep carcinogenesis

This review highlights current knowledge of environmental factors in carcinogenesis and their cellular targets. The hypothesis that environmental factors influence carcinogenesis is widely supported by both epidemiological and experimental studies. The fact that only a small fraction of cancers can be attributed to germline mutations in cancer-related genes further buttresses the importance of environmental factors in carcinogenesis. Furthermore, penetrance of germline mutations may be modified by either environmental or other genetic factors. Examples of environmental factors that have been associated with increased cancer risk in the human population include chemical and physical mutagens (e.g. cigarette smoke, heterocyclic amines, asbestos and UV irradiation), infection by certain viral or bacterial pathogens, and dietary non-genotoxic constituents (e.g. macro- and micronutrients). Among molecular targets of environmental influences on carcinogenesis are somatic mutation (genetic change) and aberrant DNA methylation (epigenetic change) at the genomic level and post-translational modifications at the protein level. At both levels, changes elicited affect either the stability or the activity of key regulatory proteins, including oncoproteins and tumor suppressor proteins. Together, via multiple genetic and epigenetic lesions, environmental factors modulate important changes in the pathway of cellular carcinogenesis.

The effect of the herbal medicine dai-kenchu-to on post-operative ileus

Post-operative ileus (PI) is an inevitable adverse consequence of abdominal surgical procedures. We performed a randomized study of the effects of the herbal medicine dai-kenchu-to (DKT) on 24 patients with PI. Patients received either 15 g of oral DKT or placebo daily for 14 days. The effects on upper gastrointestinal motility, frequency of secondary operation and recurrence of PI were investigated. The frequency of surgical operation was significantly lower in patients receiving DKT compared with placebo. Oral administration of DKT was clinically effective for PI in reducing both the need for further surgery and the recurrence of PI.

Endosonographic evaluation of c-kit-positive gastrointestinal stromal tumor

BACKGROUND

Endosonographic features of c-kit-positive gastrointestinal stromal tumors (GISTs) were compared with those of leiomyomas and schwannomas.

METHODS

Twenty-four patients with gastric mesenchymal tumors who underwent endoscopic ultrasonography (EUS) and surgical treatment were enrolled. GISTs were defined as c-kit (CD117)-positive tumors, leiomyomas as desmin-positive and c-kit-negative tumors, and schwannomas as S-100-positive and c-kit-negative tumors. Invasion to adjacent organs or more than 20 mitotic counts per 50 high power fields indicated malignancy.

RESULTS

There were 19 GISTs, three leiomyomas, and two schwannomas. All five malignant tumors were GISTs. A marginal halo was found in 12 of 19 GISTs and in both of the schwannomas, but not in any of the three leiomyomas. The echogenicities of GISTs were low but higher than that of the normal proper muscle layer, whereas those of leiomyomas and schwannomas were usually low. Lobulation of the tumor surface was documented only in GISTs, particularly in malignant ones. The tumor doubling time of a malignant GIST was 9.3 months, and that of six benign GISTs was 18.7 months (range = 10.7-28.0 months).

CONCLUSION

Marginal halo and relatively higher echogenicity on EUS might suggest GIST. Marginal lobulation and a short doubling time may be signs of a malignant GIST.

Preparation of specific antibodies against murine IL-1ra and the establishment of IL-1ra as an endogenous regulator of bacteria-induced fulminant hepatitis in mice

Blocking monoclonal antibodies (mAbs) specific to mouse interleukin-1 receptor antagonist (IL-1ra) were prepared by immunizing Armenian hamsters with recombinant mouse IL-1ra. A sensitive and specific ELISA against mouse IL-1ra was also established. In Propionibacterium acnes-induced liver injury, P. acnes induced transient increase of serum tumor necrosis factor-alpha levels but not those of IL-1ra, IL-1, and IL-6. However, subsequent lipopolysaccharide (LPS) challenge induced the increase of serum levels of all these cytokines and the peak serum IL-1ra level was more than 20 times as high as serum IL-1 levels. Immunohistochemical analysis demonstrated that IL-1ra was predominantly produced by hepatocytes during the course of the priming phase by P. acnes and eliciting phase by LPS challenge. Furthermore, the administration of a mAb to mouse IL-1ra exacerbates the liver injury induced by P. acnes and sublethal dose of LPS, suggesting a protective role of endogenous IL-1ra in this liver injury model.

Medullary carcinoma with lymphocytic infiltration of the stomach. Clinicopathologic study of 27 cases and immunohistochemical analysis of the subpopulations of infiltrating lymphocytes in the tumor

The current study attempts to clarify the possible immune response that occurs in medullary carcinoma with lymphocytic infiltration of the stomach by an immunohistochemical analysis of the subpopulations of tumor-infiltrating lymphocytes. This carcinoma was histologically characterized by the sparse population of small nests consisting of poorly differentiated carcinoma cells, widely separated by intervening nondesmoplastic stroma infiltrated uniformly with abundant lymphocytes frequently accompanied by lymph follicles. An immunohistochemical analysis revealed that T-cells were evenly distributed throughout the tumor with intimate contact with individual carcinoma cells, except the lymph follicles consisted mainly of B-cells. Because of the similarities of morphologic features and subpopulations of tumor-infiltrating lymphocytes of this carcinoma to the normal lymphoid tissue, an organized immune response combined with cell-mediated and humoral immunities against the invading carcinoma cells seemed to occur in this type of gastric carcinoma, resulting in a excellent prognosis compared with that in ordinary gastric carcinoma.

Alpha-fetoprotein (AFP)-producing gastric carcinoma. Is it hepatoid differentiation?

Biochemical and immunohistochemical analyses were done on five cases of gastric carcinoma with excessive production of alpha-fetoprotein (AFP). Histologic and ultrastructural examination of these cases showed conventional poorly differentiated adenocarcinoma of cuboidal or polygonal tumor cells in the medullary area with scattered AFP-positive cancer cells. Comparative studies on serum AFP between these cases and in hepatocellular carcinoma (HCC) or in testicular yolk sac tumor cases using concanavalin A (ConA)-affinity and lens culinalis agglutinin A (LCA)-affinity sepharose columns revealed that the AFP derived from four cases had a high ConA nonadsorping rate and high LCA-reactive fraction similar to that of yolk sac tumor. The AFP from one case had a small LCA-reactive fraction similar to that of HCC. Further immunohistochemical study using several markers for liver cells or germ cell tumor did not show additional evidence of these tumor cells to differentiate into liver cells or yolk sac tumor cells. Thus, this study indicates that AFP-producing gastric carcinomas are not always derived from hepatoid differentiation of the foregut. These gastric carcinomas might be categorized into medullary tumor with gastrointestinal tract-specific AFP.

Cloning of the human homolog of conductin (AXIN2), a gene mapping to chromosome 17q23-q24

Conductin or Axil, an Axin homolog, plays an important role in the regulation of beta-catenin stability in the Wnt signaling pathway. To facilitate the molecular analysis of the human gene, we isolated the human homolog, AXIN2. The cDNA contains a 2529-bp open reading frame and encodes a putative protein of 843 amino acids. Compared with rat and mouse homologs, AXIN2 shows an overall 89% amino acid identity. Several functional domains in this protein are highly conserved including the GRS (95.9%), GSK-3beta (96.3%), Dsh (98%), and beta-catenin (89.9%) domains. Radiation hybrid mapping localized the AXIN2 gene to human chromosome 17q23-q24, a region that shows frequent loss of heterozygosity in breast cancer, neuroblastoma, and other tumors. Human AXIN2 is thus a very strong candidate involved in multiple tumor types.

Genomic organization and mutation analysis of p73 in oligodendrogliomas with chromosome 1 p-arm deletions

p73, a protein having substantial structural and functional similarity to p53, has recently been identified and demonstrated to be a potential tumor suppressor. Its location on human chromosome 1p36.33 implicates p73 as a candidate for neuroblastoma. Like neuroblastoma, oligodendrogliomas also show a high frequency of deletions in chromosome 1p36.3. To determine whether p73 is a potential tumor suppressor gene involved in the development of oligodendrogliomas, we performed mutation analysis of p73 in oligodendrogliomas with chromosome 1 p-arm deletions. We first determined the genomic organization and the intron-exon boundary sequences of the p73 gene by long PCR, vectorette PCR, and Southern hybridization. This gene spans about 65 kb with a large first intron. Primer pairs for the amplification of each of the 13 p73 encoding exons were designed in corresponding introns. The amplicons were then analyzed using the denaturing high-performance liquid chromatography system for mutations in the p73 gene. Twenty oligodendroglioma samples with 1p36.3 deletions were screened, but no mutations were detected except for several polymorphisms. It is thus clear that p73 is not a candidate gene for oligodendroglioma despite its location in the frequently deleted 1p36.3 region.

Bilateral vestibular loss, oscillopsia, and the cervico-ocular reflex

Oscillopsia during head movement occurs in patients with bilateral vestibular loss and may be transient or persistent. To investigate mechanisms underlying recovery we tested the vestibulo-ocular reflex (VOR), visual-vestibular interaction, and the cervico-ocular reflex (COR); we used a pseudorandom oscillatory stimulus with a frequency band width of 0 to 5 Hz in six patients with bilaterally absent caloric responses and in 10 normal controls. Seven control subjects had low-gain COR responses, but these were anticompensatory with respect to the VOR. Three asymptomatic patients with an absent or grossly deficient VOR had increased oculomotor responses at all frequencies when oscillated in light. Compensatory COR responses were detected in these patients but not in patients with persisting oscillopsia. In some patients with bilateral vestibular loss, augmented cervico-ocular and visual reflexes may compensate, at least partially, for an absent VOR.

Loss of imprinting and allele switching of p73 in renal cell carcinoma

p73, a protein that has substantial structural and functional similarity to p53, has recently been identified. It was found to be monoallelically expressed in all cell lines and normal individuals tested. To elucidate its role in cancer development and as a potential imprinted tumor suppressor, we investigated the allele-specific expression of the human p73 gene in 28 cases of renal cell carcinoma and its imprinting status in fetal pancreatic and thymic tissues. Of 12 informative pairs of renal cell carcinoma and matched normal tissues identified by StyI restriction fragment length polymorphism (RFLP) in exon 2, p73 showed monoallelic expression in 11 out of 12 normal tissues but biallelic expression in 8/12 and switched allele expression in 2/12 of the matched corresponding cancers. An imprinting study of the p73 gene in two families using a newly identified exonic BanI RFLP indicated that expression of p73 was limited to the maternal allele in RNA from fetal pancreas and thymus, demonstrating that p73 is imprinted in at least these two tissues. These findings strongly suggest that loss of imprinting or switching of allelic expression of the p73 gene is associated with the development of renal cell carcinoma.

The changing direction of nystagmus in acute Menière's disease: pathophysiological implications

The direction(s) and pathophysiologic basis of nystagmus during an acute attack of Menière's disease have been subject to much debate in the world literature. Clinical recordings from two patients whose nystagmus was captured near the very beginning of the acute vertiginous episode are presented. Previous clinical observations in Meniere's disease, experimental animal models concerned with initiation of peripheral nystagmus, and the phenomenon of recovery are discussed.

A blue luminescent MOF as a rapid turn-off/turn-on detector for H2O, O2and CH2Cl2, MeCN: 3∞[Ce(Im)3ImH]·ImH

A blue emitting MOF is presented as a fast turn-off/turn-on detector for various analytes utilising 5d–4f-transitions of Ce³⁺.

Endocrine differentiation of gastric adenocarcinoma. The prevalence as evaluated by immunoreactive chromogranin A and its biologic significance

The prevalence of endocrine differentiation of conventional gastric adenocarcinoma was evaluated on the 212 cases (including 62 mucosal carcinomas) of consecutively resected stomach for adenocarcinoma in our hospital using anti-chromogranin A (CGA) antibodies. CGA-positive cells were found in 28 of 150 cases (18.7%) as an integral tumor component. In immunocytochemistry and electron microscopic examinations, we could classify these 28 cases into three groups according to the distribution patterns of CGA-positive cells. The first group consisted of 12 cases in which scattered CGA-positive cells were located in neoplastic glands. The second group consisted of six cases of scirrhous carcinoma in which CGA-positive cells were separated by fibrovascular tissue. The third group consisted of ten cases in which the positive cells were present in clusters. No definite correlation was recognized between the appearance of CGA cells and histologic types of predominance. In the analysis of the hormonal substances coexpressed by CGA-positive cells, immunoreactive serotonin (SER) was found most frequently, and somatostatin (SS), gastrin (GAS), glucagon/glicentin (GLU/GLI), and peptide-tyrosine-tyrosine (PYY) like immunoreactivities were found in a few tumor cells. CGA-positive cells occupied limited parts of the tumors in most cases, and they were noticeably more frequent in advanced stage cases. This might explain why endocrine differentiation reflects the dysexpression of the neoplastic stem cells. Furthermore, absence of mitotic figures in this type of cell and negativity of a single colony composed exclusively of CGA cells in metastatic foci suggested that these cells are in a dormant phase and are probably postmitotic.

Inhibition of metastasis in human gastric cancer cells transfected with tissue inhibitor of metalloproteinase 1 gene in nude mice

BACKGROUND

Tissue inhibitors of metalloproteinases (TIMPs) act as negative regulators of matrix metalloproteinases (MMPs) that degrade extracellular matrix. We evaluated the metastatic ability of the highly metastatic human gastric cell line KKLS, and that of cells transfected with exogenous TIMP-1 gene by the orthotopic transplantation model in nude mice.

METHODS

KKLS was derived from human gastric cancer. Expression of mRNA for tissue inhibitor of metalloproteinase-1 (TIMP-1) was almost undetectable in KKLS cells. KKLS cells were transfected with exogenous TIMP-1 gene by the Chen-Okay-ama method. Two clones (KTCLs) that expressed different levels of TIMP-1 and neomycin-resistant KKLS (K-neo) were obtained. The KKLS cells and these transfectants were orthotopically transplanted into nude mice (murine stomach) and metastasis in the murine liver was detected. As a method of detecting metastasis, we used a DNA fragment (human beta-globin gene) specific to human tumor cells that have metastasized into the murine liver by polymerase chain reaction (PCR).

RESULTS

Differences in tumor growth in the murine stomach were not observed between KKLS cells, K-neo cells, and the two transfectants expressing the different TIMP-1 levels (low, KTCL-1; high, KTCL-14). The KKLS cells and K-neo cells had undergone liver metastasis, as shown by PCR amplification of the human beta-globin gene fragment from the murine liver samples, since Week 1 after transplantation and the metastasis had grown exponentially; however, although KTCL-1 cells and KTCL-14 cells had undergone liver metastasis since Week 2, the metastasis had not grown. The average intensities of the amplified gene fragments from K-neo cells, KTCL-1 cells, and KTCL-14 cells in Week 4 after transplantation were 100%, 45%, and 18%, respectively, of the parenteral KKLS cells.

CONCLUSIONS

TIMP-1 was suggested to act as a negative regulator of the metastasis. The present data is thought to be especially important because the mice in this study underwent orthotopic transplantation with a metastatic model.