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Biomedical subjects

I Horikawa

Publications and source records attributed to I Horikawa.

31 records · Page 2Linked to original sources
PubMed1995

Molecular cloning of a novel human cDNA on chromosome 1q21 and its mouse homolog encoding a nuclear protein with DNA-binding ability.

We previously reported that human chromosome 1q21 or 1q23-q24 carries a transformation suppressor gene(s) for Kirsten sarcoma virus-transformed NIH3T3 cells. In this study, we have isolated a novel human cDNA on 1q21 (designated as YL-1) as a candidate, then cloned its mouse homolog. Human and mouse YL-1 cDNA shared 96% in amino acid homology and presumably encoded a transcription factor-like polypeptide. An analysis using a specific antibody revealed the nuclear localization of YL-1 protein. The bacterially expressed YL-1 could bind to DNA. Thus, YL-1 protein possibly functions as a transcriptional regulator.

3T3 Cells↗
PubMed1995

Normal human chromosome 2 induces cellular senescence in the human cervical carcinoma cell line SiHa.

For identification of the chromosome carrying cellular senescence-inducing activity, normal human chromosome 2, 3, 6, 7, 9, 11, or 12 tagged with a selectable marker gene (neo) was introduced into the human cervical carcinoma cell line SiHa via microcell-mediated chromosome transfer. Seventy-six percent (158/207) of the G418-resistant clones obtained by the transfer of chromosome 2 showed a remarkable change in morphology (cells were flat), and 93% (147/158) of them ceased to divide (senesced) prior to 6-9 population doublings, whereas most of the clones generated by the transfer of other chromosomes exhibited a morphology similar to that of the parental cells and continued to grow. Chromosome analyses suggested that cells which escaped from senescence contained only a small fragment derived from the transferred chromosome 2, whereas the transferred chromosomes were apparently intact in most of the continuously growing microcell hybrids with introduction of other chromosomes. These results indicate that the normal human chromosome 2 carries a gene or genes that induce cellular senescence in SiHa cells.

Animals↗
PubMed1995

Forced expression of YL-1 protein suppresses the anchorage-independent growth of Kirsten sarcoma virus-transformed NIH3T3 cells.

The YL-1 gene, encoding a novel nuclear protein with transcription factor-like features, has been isolated from the human chromosome 1q21, one of the regions supposedly carrying a transformation suppressor gene(s) for Kirsten sarcoma virus-transformed NIH3T3 (DT) cells. To test the suppressive activity of the YL-1 gene product, we forced the expression of human YL-1 cDNA in DT cells. The anchorage-independent growth (colony-forming ability in soft agar medium) was markedly suppressed in cells highly expressing the exogenous human YL-1 protein. Moreover, the soft agar clones, which were rarely originated from these cells, expressed reduced levels of exogenous YL-1 or none, with or without the loss/rearrangement of the introduced cDNA. In control experiments, cells carrying an introduced vector alone or an antisense-strand expression plasmid grew in soft agar as efficiently as parental DT cells. In contrast to the suppression of anchorage-independent growth, the forced expression of YL-1 did not effect the transformed phenotypes in adherent culture and tumorigenicity in nude mice. These findings not only indicated that the YL-1 protein functions as a transformation suppressor, but also suggest that it may be important for elucidating anchorage independence under separate genetic control from other transformed phenotypes.

3T3 Cells↗
PubMed1995

Genetic heterogeneity of chromosome 11 associated with tumorigenicity in HeLa D98-OR cells.

D98-OR is a tumorigenic subline of HeLa cells. We isolated nine subclones from D98-OR and examined their tumorigenicity in nude mice. Three, two, and four subclones were highly, weakly, and nontumorigenic, respectively. While they all contained two copies of intact chromosome 11, restriction fragment length polymorphism (RFLP) analysis revealed that the allelic composition of this chromosome differed among them. The highly tumorigenic subclones were heterozygous for the 11p and 11q loci, whereas those that were weakly or nontumorigenic were homozygous. Thus, the loss of one chromosome 11 with the duplication of another associated with the reduced tumorigenicity. Taken together with previous reports, our results indicate that a putative tumor suppressor gene on chromosome 11 controls tumorigenic expression in a gene dosage-dependent manner, and most importantly, suggested that the functional inactivation of the gene requires only a "one-hit" mutation.

Animals↗
PubMed1995

Subchromosomal mapping of a putative transformation suppressor gene on human chromosome 1.

We previously reported that the introduction of a normal human chromosome 1 via microcell-mediated chromosome transfer suppressed the transformed phenotypes, including anchorage-independent growth, of Kirsten murine sarcoma virus-transformed NIH3T3 (DT) cells. Soft-agar clones derived from DT-#1 cells (DT cells with an intact transferred human chromosome 1) exclusively failed to retain an intact form of this chromosome. Thus, a gene(s) with a suppressive activity on this chromosome had probably been lost. We therefore attempted to identify a commonly deleted region on human chromosome 1 in these soft-agar clones. Although eight of the 9 soft-agar clones examined still contained regions on this chromosome, to a greater or lesser degree, four loci on 1q21 and 1q23-q24 were commonly lost in all of them. Furthermore, the soft-agar clones had growth properties similar to those of DT cells. Thus, chromosome and DNA analyses suggested that human 1q21 and/or 1q23-q24 carries a transformation suppressor gene(s) which controls the transformed phenotypes of DT cells.

3T3 Cells↗
PubMed1995

[Studies on tumor suppressor genes by gene/chromosome transfer].

The gene/chromosome transfer into cultured cancer cells has not only confirmed that genes isolated by the positional cloning method can actually suppress various transformed phenotypes of the cells, but also allowed to speculate cellular functions of cloned or uncloned tumor suppressor genes. One of the important functions of uncloned ones is to induce the cellular senescence program in immortal cancer cells, as revealed by the chromosome transfer. This method has also identified novel chromosomes (or chromosomal regions) carrying putative tumor suppressor genes, which have never been suggested by other approaches, e.g., LOH analyses. Thus, the studies on tumor suppressor genes using cultured cancer cells have different advantages from those of the molecular genetics/molecular biology studies.

Animals↗
PubMed1991

Normal human chromosome 5, on which a familial adenomatous polyposis gene is located, has tumor suppressive activity.

The suppressive activity of normal human chromosome 5 was detected by means of the chromosomal transfer technique using DT cells as recipients. A hybrid clone, which exhibited reduced tumorigenicity, contained chromosomal regions such as 5pter-p15, q21 and q33-qter. Since a familial adenomatous polyposis gene has been reported to be located at 5q21-q22, the suppressive activity of chromosome 5 might be due to this gene.

Adenomatous Polyposis Coli↗
PubMed1991

[Tumor-suppressor genes].

The existence of tumor-suppressor genes has been primarily suggested by three lines of evidences: 1) the suppression of transformed phenotypes of tumor cells by cell-cell hybridization with normal cells; 2) non-random chromosome deletions in a variety of tumors; 3) loss of heterozygosity in specific chromosomal regions in tumor cells. Results from monochromosome transfer experiments also suggest the existence of multiple, functionally distinct tumor-suppressor genes. Recently, several tumor-suppressor genes, which appeared to be functionally distinct, (i.e., Rb gene, WT gene and DCC gene) were isolated. Most recently, it was suggested that the inactivations of at least three different tumor-suppressor genes were required for the colorectal carcinogenesis at different steps. Thus, these findings support that losses or alterations in the dosage of multiple tumor-suppressor genes play crucial roles during initiation and/or progression of a wide variety of cancers.

Eye Neoplasms↗
PubMed1990

Normal human chromosome 1 carries suppressor activity for various phenotypes of a Kirsten murine sarcoma virus-transformed NIH/3T3 cell line.

In order to identify chromosomes that carry putative tumor-suppressor genes for the various phenotypes of Kirsten sarcoma virus-transformed NIH/3T3 (DT) cells, we performed microcell-mediated chromosome transfer into DT cells. We first isolated mouse A9 clones, containing a single human chromosome 1, 11 or 12 tagged with pSV2-neo plasmid DNA. Then, chromosome 1, 11 or 12 was transferred from the A9 clones into DT cells by microcell fusion. The growth rate, colony-forming ability in soft agar and tumorigenicity of the DT cells were controlled by chromosome 1, but not by chromosome 11 or 12, indicating that normal human chromosome 1 carries a putative tumor-suppressor gene(s) that affects various transformed phenotypes of DT cells.

Animals↗
PubMed1990

[The incidence and clinical significance of paraaortic lymph node metastases in patients with uterine cervical cancer].

Paraaortic lymph node dissection was performed in the treatment of patients with carcinoma of the cervix who were subjected to radical hysterectomy between June, 1982 and March, 1988 at the Department of Obstetrics and Gynecology, Hokkaido University Hospital, Sapporo, Japan. Thirteen out of 246 (5.3%) patients had metastases in the paraaortic lymph node. Of the patients with stage I carcinoma of the cervix, 1.0 per cent had positive paraaortic lymph node. Of the patients with stage II carcinoma, 4.9 per cent had metastases in the paraaortic lymph nodes, and of the stage III patients, 16.7 per cent had positive paraaortic lymph nodes. The incidence of paraaortic node involvement increased along with the advance of the disease. Of the patients with squamous cell carcinoma of the cervix, 4.6 per cent had paraaortic lymph node metastases. Of the patients with adenocarcinoma of the cervix including mixed carcinoma, 6.8 per cent had positive paraaortic node. All the patients with positive paraaortic lymph nodes had metastatic diseases in the pelvic nodes. In addition, the number of groups of positive pelvic nodes in the patients with positive paraaortic lymph nodes was significantly larger than that in those with negative paraaortic nodes. At the time of reporting, seven out of 13 patients with positive paraaortic lymph node have died of the disease. The mean survival period of those seven patients was 14.9 +/- 12.2 (mean +/- SD) months. Of the remaining six surviving patients, three have been doing well for more than three years.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1989

Multiple chromosomes carrying tumor suppressor activity, via microcell-mediated chromosome transfer, for various tumor cell lines.

The ability of normal human fibroblast-derived chromosomes to suppress tumorigenicity in nude mice and in vitro growth properties of various tumor cell lines was examined. Normal human chromosomes tagged with pSV2neo gene by DNA transfection were transferred to the following human tumor cell lines by microcell-fusion: SiHa (uterine cervical carcinoma), A204 (rhabdomyosarcoma), SK-NEP-1 (Wilms' tumor), HHUA (uterine endometrial carcinoma), SK-N-MC (neuroblastoma), YCR (renal cell carcinoma), HT1080 (fibrosarcoma), and CC1 (chorionic carcinoma). The results indicate the presence of a putative tumor-suppressor gene(s) in multiple chromosomes, and suggest that multiple genes may normally be involved in suppressing the transformed phenotypes at different stages in some tumors. Thus, the microcell transfer of chromosomes to specific tumor cell lines is a useful technique to demonstrate the presence of tumor-suppressor genes on individual chromosomes, and may also be useful in cloning of tumor-suppressor genes as well as elucidating their function in cell-growth and differentiation.

Animals↗