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M You

Publications and source records attributed to M You.

At least 73 records · Page 4Linked to original sources
PubMed1997

Detection of differentially expressed genes in methylnitrosourea-induced rat mammary adenocarcinomas.

In this study, altered gene expression in five methylnitrosourea (MNU)-induced rat mammary adenocarcinomas was investigated using a newly developed competitive cDNA library screening assay. In order to detect the differentially expressed cDNA transcripts, three cDNA libraries (rat mammary, rat liver, and rat kidney) with over 18,000 clones were differentially screened with competing normal and neoplastic mammary cDNA probes. Ninety-eight clones indicated by competitive hybridization to be differentially expressed in tumors were verified by dot-blot hybridization analysis. Of these clones, 45 were found to be overexpressed while 53 were underexpressed in tumors. Forty-five of the confirmed clones were further analyzed by single-pass cDNA sequence determination. Four clones showed homology with cytochrome oxidase subunit I, polyoma virus PTA noncoding region, cytoplasmic beta-actin, and mouse secretory protein containing thrombospondin motifs. Further investigation into the potential roles of these identified genes should contribute significantly to our understanding of the molecular mechanism(s) of rat mammary tumorigenesis.

Adenocarcinoma↗
PubMed1996

The 5'-flanking region of the E1 alpha form of the murine p16INK4a (MTS1) gene.

We have PCR-amplified and sequenced the immediate (841 bp) 5'-flanking region of murine p16INK4a (MTS1, CDKN2) tumor suppressor gene. Comparing to recently published 5'-flanking region of the human alpha form of p16INK4a, homologies were found in several regions of murine p16INK4a-alpha putative promoter sequence.

Animals↗
PubMed1996

Homozygous codeletion and differential decreased expression of p15INK4b, p16INK4a-alpha and p16INK4a-beta in mouse lung tumor cells.

The genes of murine cyclin D-dependent kinase inhibitors, p15INK4b and p16INK4a, are located in a region of chromosome 4 where overlapping deletions were found in lung adenocarcinomas. The p16INK4a gene uniquely consists of alternative first exons (E1alpha and E1beta), which are spliced to exon 2 in alternative reading frames to either encode p16INK4a (alpha form) or another potential tumor suppressor, p19ARF (beta form). We examined 99 lung adenocarcinomas of C3H/HeJ x A/J F1(C3AF1) and A/J x C3H/HeJ F1(AC3F1) mouse hybrids and 18 (13 metastatic, 5 nonmetastatic) tumorigenic mouse lung epithelial cell lines for p15INK4b and p16INK4a gene inactivation. Homozygous codeletion occurred in eight of the 13 (62%) metastatic, four of the five (80%) nonmetastatic cell lines, but in only six of 99 (6%) adenocarcinomas. Neither p15INK4b nor p16INK4a gene was individually deleted in any of the tumors or cell lines, and all deletions of the p16INK4a gene extended into exon 2, which would be expected to disrupt the functions of both p16INK4a and p19ARF. We also detected no intragenic mutations of either gene in 44 tumors that displayed loss of heterozygosity at the p16INK4a locus or in any of the cell lines. Transcript levels of p16INK4a-alpha, p16INK4a-beta and p15INK4b also were examined in each of the cell lines that retained copies of these genes. Whereas an immortal mouse lung epithelial cell line (E10) and two metastatic tumor cell lines (LM1 and E9) expressed p16INK4a-beta and p15INK4b mRNA, the alpha transcript of p16INK4a was detected in only the LM1 cell line. These results suggest that both p15INK4b and p16INK4a (alpha and beta) are targets of inactivation in mouse lung tumorigenesis.

Adenocarcinoma↗
PubMed1996

Activation of mitogen-activated protein (MAP) kinase pathway by pervanadate, a potent inhibitor of tyrosine phosphatases.

Rapid tyrosine phosphorylation of key cellular proteins is a crucial event in signal transduction. The regulatory role of protein-tyrosine phosphatases (PTPs) in this process was explored by studying the effects of a powerful PTP inhibitor, pervanadate, on the activation of the mitogen-activated protein (MAP) kinase cascade. Treatment of HeLa cells with pervanadate resulted in a marked inhibition of PTP activity, accompanied by a drastic increase in tyrosine phosphorylation of cellular proteins. The increased tyrosine phosphorylation coincided with the activation of the MAP kinase cascade as indicated by enzymatic activity assays of MEK (MAP kinase/ERK-kinase) and MAP kinase and gel mobility shift analyses of Raf-1 and MAP kinase. The activation was sustained but reversible. Upon removal of pervanadate, both tyrosine phosphorylation and MAP kinase activation declined to basal levels. Therefore, inhibition of PTP activity is sufficient per se to initiate a complete MAP kinase activation program.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1996

Loss of heterozygosity on chromosomes 1, 11, 12, and 14 in hybrid mouse lung adenocarcinomas.

An allelotype analysis of lung tumors in mouse hybrids was conducted to identify common regions of allelic loss. By using 50 informative genetic markers, the autosomes of 36 (A/J x C3H/HeJ) F1 adenocarcinomas were examined. Additional adenocarcinomas from as many as 72 (C3H/HeJ x A/J) F1 and 15 (BALB/cJ x DBA/2J) F1 hybrids also were analyzed for DNA loss at some of the loci. Loss of heterozygosity (LOH) was observed at multiple loci and occurred with the most regularity at markers on chromosomes 12 (28%), 14 (28%), 11 (21%), and 1 (20%). The frequency of LOH was not greater than 11% on any of the other chromosomes. Chromosomes 11 and 14 often displayed allelic loss at markers located near the p53 and retinoblastoma tumor suppressor loci, respectively. LOH at markers on chromosomes 12 and 14 was associated with tumors having overall frequencies of allelic loss that exceeded the median value. Losses on chromosomes 1, 11, 12, and 14 also showed a significant association with the adenocarcinoma stage of mouse lung tumorigenesis, suggesting that the inactivation of tumor suppressor loci on these chromosomes may participate in the progression of these tumors.

Adenocarcinoma↗
PubMed1996

Detection of genomic alterations in human cervical cancer by two-dimensional gel electrophoresis.

Two-dimensional gel electrophoresis was used to comprehensively scan the whole genome of 6 cervical intraepithelial neoplasia (CIN) lesions, 7 cervical squamous cell carcinomas, 1 cervical adenosquamous cell carcinoma, and 2 cervical adenocarcinomas for multiple genetic alterations, such as DNA amplification, chromosome deletion, loss of heterozygosity, and chromosome translocation, as compared with the paired normal tissues. DNA spot analysis of the genomic 2-dimensional gels was performed by a computer color overlay system and by spot recognition software allowing for objective spot comparison and quantitation. Nine spots were found to be amplified in the cervical carcinomas while two amplified spots were detected in the CIN III lesions. Fourteen DNA spots were either reduced in their intensity or absent in cervical carcinomas as compared to their normal paired tissues. Reduction of intensity in 6 spots was observed in the 5 CIN III lesions. These genetic alterations may represent changes in cancer genes that are associated with human cervical carcinogenesis. Further characterization of these alterations may be significant to the understanding of cervical tumorigenesis and to the development of biomarkers for clinical trials in cancer chemoprevention.

Adenocarcinoma↗
PubMed1996

DNA quantification in cervical intraepithelial neoplasia thick tissue sections by confocal laser scanning microscopy.

Image analysis of tissue biopsies for determination of DNA content as an early marker of neoplasia is hampered by the complexity of corrections necessary to dea with nuclear truncation and overlap in thin sections. The use of confocal laser scanning microscopy (CLSM) for measurement of cellular DNA content on whole cells within thick tissue sections offers the advantage of preservation of cellular architecture, capacity for 3-dimensional analysis, and absence of sectioning artifacts. We have applied this technique to pararosaniline-Feulgen stained human cervical tissues graded from normal to cervical intraepithelial neoplasia (CIN) III. For the purpose of comparison, 15 microns sections were stained and mapped so that the same cell population could be analyzed by both integrated optical density and fluorescence intensity. Distribution of DNA content from normal cervical epithelial cells 2-3 layers out from the basal cell layer measured by both methodologies showed a stable G0/G1 population with no observable S-phase or G2 cells. Cells measured from areas of increasing CIN grade showed progressively higher DNA content values that were not observable in normal tissue. Although these data are preliminary they suggest that CLSM can be used to identify aneuploid states within defined structural areas of pre-invasive neoplasia.

Coloring Agents↗
PubMed1995

Allelic loss of distal chromosome 4 in mouse lung tumors localize a putative tumor suppressor gene to a region homologous with human chromosome 1p36.

Loss of heterozygosity (LOH) of distal chromosome 4 was studied to localize a putative tumor suppressor gene in mouse lung neoplasia. Previous studies have implicated this region and its homologue on human chromosome 1p36-34 as sites of potential tumor suppressor genes. One hundred adenocarcinomas and 38 adenomas of the mouse lung were examined for LOH using nine simple sequence length polymorphism markers in a polymerase chain reaction-based approach. Forty-four adenocarcinomas displayed allele loss, all of which included losses at marker D4MIT54, which defined a critical region of 3 centiMorgans as the likely location of a putative tumor suppressor gene. In 58% of the tumors displaying LOH, all markers used in this study incurred allele loss. In contrast, retention of heterozygosity was observed at all markers tested in each of the adenomas studied, which suggests that the inactivation of this tumor suppressor gene participates in mouse lung tumor progression.

Adenocarcinoma↗
PubMed1995

(-)-Roemerine, an aporphine alkaloid from Annona senegalensis that reverses the multidrug-resistance phenotype with cultured cells.

A known aporphine alkaloid, (-)-roemerine [1], isolated from the leaves of Annona senegalensis, was found to enhance the cytotoxic response mediated by vinblastine with multidrug-resistant KB-V1 cells. In the absence of vinblastine, no significant cytotoxicity was observed with KB-3 or KB-V1 cells (ED50 > 20 micrograms/ml), and several other human tumor cell lines were also relatively insensitive. As indicated by its ability to inhibit ATP-dependent [3H]vinblastine binding to multidrug-resistant KB-V1 cell membrane vesicles, (-)-roemerine appears to function by interacting with P-glycoprotein. In addition to alkaloid 1, three inactive compounds [the aporphine alkaloid(-)-isocorydine (reported in the levo-configuration for the first time), and the lignans (+/-)-8,8'-bisdihydrosiringenin [2] (a new natural product), and (+)-syringaresinol] were also isolated.

Africa↗
PubMed1995

K-ras mutations in lung tumors from A/J and A/J x TSG-p53 F1 mice treated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and phenethyl isothiocyanate.

The purpose of this study was to evaluate the effects of the loss of a p53 allele and phenethyl isothiocyanate (PEITC) pre-treatment on the tumorigenicity of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and K-ras mutation frequency in a hybrid mouse model. Male TSG-p53 'knock-out' mice were bred with A/J female mice to produce (A/J x TSG-p53) F1 mice either homozygous (p53+/+) or heterozygous (p53+/-) for p53 alleles. These mice, together with female A/J mice, were treated at 6-8 weeks of age with NNK or dosed with PEITC prior to administration of NNK. The A/J mice treated with NNK had a 100% incidence of lung tumors, with 9.7 +/- 3.4 tumors/mouse. A/J mice pre-treated with PEITC prior to NNK administration had 3.5 +/- 2.1 lung tumors/animal, although the incidence remained at 100%. In (A/J x TSG-p53) F1 mice with either the p53(+/-) or p53(+/+) genotype PEITC pre-treatment significantly decreased tumor incidence (100 to 40 and 36%, respectively) and multiplicity (2.0 +/- 0.5 to 0.5 +/- 0.4 and 2.1 +/- 0.5 to 0.5 +/- 0.4, respectively), indicating that PEITC is an effective chemopreventive agent in both A/J mice and (A/J x TSG-p53) F1 mice. Analysis of lung tumor DNA from A/J mice treated with NNK or NNK/PEITC indicated that 15 of 17 (88%) and 20 of 23 (87%) of the tumors, respectively, contained G-->A transitions at the second base of codon 12 in the K-ras gene. Similarly, in lung tumors from (A/J x TSG-p53) F1 mice treated with NNK or NNK/PEITC 29 of 30 (96%) and 9 of 10 (90%), respectively contained G-->A transitions at the second base of codon 12 of the K-ras gene. No mutations of the p53 gene were found in any of the tumors analyzed, suggesting minimal involvement of this gene in the development of lung adenomas. These data indicate that absence of a p53 allele in (A/J x TSG-p53) F1 mice does not alter the incidence or multiplicity of NNK-induced lung tumors and that PEITC inhibition of NNK tumorigenesis does not affect the frequency or spectrum of K-ras gene mutations found consistently with NNK carcinogenesis.

Animals↗
PubMed1995

Cancer chemopreventive activity of brassinin, a phytoalexin from cabbage.

Brassinin [3-(S-methyldithiocarbamoyl)aminomethyl indole], a phytoalexin first identified as a constituent of cabbage, was synthesized and evaluated for cancer chemopreventive activity. Dose-dependent inhibition of 7,12-dimethylbenz[a]anthracene (DMBA)-induced preneoplastic lesion formation was observed with mouse mammary glands in organ culture, as was dose-dependent inhibition of DMBA-induced mouse skin tumors that were promoted by treatment with 12-O-tetradecanoylphorbol-13-acetate. Cyclobrassinin is a biologically derived product of the oxidative cyclization of brassinin, and was as active as the parent compound in inhibiting the formation of preneoplastic mammary lesions in culture; however, 2-methylbrassinin was not significantly active in this process. Therefore, oxidative cyclization may be an effective metabolic activation step. As judged by these tumor inhibition studies in conjunction with potential to induce phase II enzymes in mice or cell culture, brassinin may be effective as a chemopreventive agent during both the initiation and promotion phases of carcinogenesis. This is the first report documenting the chemopreventive potential of structurally novel indole-based phytoalexins that are naturally occurring in cruciferous vegetables, and the synthetic route described herein has proven amenable for scale-up production. The bifunctional structural nature of brassinin, bearing both an indole nucleus and a dithiocarbamoyl-aminomethyl moiety, is notably similar to the individual structural elements of other known chemopreventive agents such as indole-3-carbinol or benzylisothiocyanate. The favorable biological activity demonstrated by the compound may originate from the presence of these two moieties.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Deletion mapping of a putative tumor suppressor gene on chromosome 4 in mouse lung tumors.

Genetic and molecular studies have implicated the region of the alpha-interferon gene cluster on mouse chromosome 4 as the location of a putative tumor suppressor gene. A region of homology on human chromosome 9p21-22 that is frequently deleted in multiple human cancers has recently been found to contain a candidate tumor suppressor gene called multiple tumor suppressor-1 (MTS1); which was previously shown to encode an inhibitor of cyclin-dependent kinase 4. We performed loss of heterozygosity and deletion analyses to map the most commonly deleted region on chromosome 4 in F1 hybrid mouse lung tumors. Ten simple sequence length polymorphism markers were analyzed with focus on the alpha-interferon region. Allelic losses were detected in 29 of 61 (48%) of the lung adenocarcinomas but in only 1 of 38 (3%) of the lung adenomas examined. In most cases, the losses appeared to occur by nondisjunction. However, in three carcinomas, we detected homozygous deletions that overlapped at simple sequence length polymorphism marker D4MIT77. These data suggest a critical region of about 2 cM immediately distal to the alpha-interferon locus as the likely domain of a novel tumor suppressor gene on mouse chromosome 4, the loss of which appears to be involved in the progression of mouse lung tumorigenesis.

Adenocarcinoma↗
PubMed1994

The second intron of the K-ras gene contains regulatory elements associated with mouse lung tumor susceptibility.

We have previously demonstrated the preferential activation of the K-ras gene from the susceptible A/J parent in lung tumors from F1 mouse hybrids. In the present study, the mechanism of this observation is further investigated. Higher levels of expression of A/J K-ras allele were detected in lung adenomas (30 of 30) from the C3A mouse. In addition, three K-ras alleles, designated as susceptible (Ks), intermediate (Ki), or resistant (Kr), were identified by sequence analysis of the second intron of the K-ras gene from 32 strains of mice. These K-ras alleles are associated with differences in mouse lung tumor susceptibility. All Kr alleles have a tandem 37-bp direct repeat (nt 282-355) in the second intron of the K-ras gene. Ks and Ki alleles have only one copy of the 37-bp sequence (nt 282-318). Ks strains have three base variations at nt 288, 296, and 494, and Ki strains have two base variations at nt 288 and 494 in the second intron of the K-ras gene. Differential protein-binding patterns were observed in gel-mobility-shift experiments between the duplicated 37-bp sequence of the Kr allele and the single 37-bp sequence of the Ks and Ki alleles. DNase I footprinting assay revealed protein binding sites in the second intron of the K-ras gene that correspond to the tandem repeat sequences. Our data suggest that higher expression of the A/J allele relative to C3H allele may be responsible for the allele-specific activation of the K-ras gene in lung tumors from F1 hybrid mice.

Adenoma↗
PubMed1994

Ki-ras mutations in 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-initiated and butylated hydroxytoluene-promoted lung tumors in A/J mice.

The promotional effects of butylated hydroxytoluene (BHT) on lung tumorigenesis induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was evaluated in a two-stage model of lung tumorigenesis in the A/J mouse. Mice were treated in two separate experiments with 1.54 mmol/kg (9.1 mg/mouse) NNK, which induced an average of 8.4 and 9.1 tumors/mouse in the experiments. Animals fed a diet that contained 1 g/kg BHT after administration of the carcinogen in these two experiments demonstrated an increase of the tumor multiplicity by 63% and 43%. Multiplicity of forestomach tumors was not effected by BHT in the diet. No differences in lung tumor morphology were seen as a result of the promoting effect of BHT. Mutations in the Ki-ras oncogene from lung tumors induced by NNK (19 tumors) or by NNK plus a diet containing BHT (34 tumors) were characterized by polymerase chain reaction, single-strand conformational polymorphism, and direct sequencing. All 19 NNK-induced tumors not promoted with BHT contained activated Ki-ras genes with GC-->AT transitions at the second base of codon 12. Only 11 of 34 NNK-induced and BHT-promoted tumors (32%) had this characteristic Ki-ras alteration. These data suggest that the NNK-initiated mouse lung tumorigenesis pathway, which involves the specific mutation of the Ki-ras oncogene, is altered to a predominantly non-ras mechanism when these tumors are promoted by BHT in the diet.

Adenoma↗
PubMed1994

Anthropometry of Taiwanese women.

This note describes the results of research into the anthropometric measurements of women in Taiwan, for use in pantihose design.

Journal Article↗
PubMed1994

Indole alkaloids from Peschiera laeta that enhance vinblastine-mediated cytotoxicity with multidrug-resistant cells.

Coronaridine [1], conoduramine [2], and voacamine [3], three indole alkaloids isolated from Peschiera laeta, have been found to enhance the cytotoxic response mediated by vinblastine [4] with multidrug-resistant KB cells. Inhibition of vinblastine binding with membrane vesicles isolated from this cell line was also assessed, and the bisindole alkaloids conoduramine [2] and voacamine [3] were found to be more potent inhibitory agents than the monomeric alkaloid, coronaridine [1]. Thus, these compounds appear to function by binding with P-glycoprotein.

Alkaloids↗
PubMed1994

Allele-specific activation and expression of the K-ras gene in hybrid mouse lung tumors induced by chemical carcinogens.

A mouse hybrid, (C3H x A/J)F1 or C3A, was developed by crossing male A/J mice (high lung tumor susceptibility) with female C3H mice (low lung tumor susceptibility). The lung tumor responses of the C3A mice to dimethylnitrosamine (DMN) or benzo[a]pyrene (B[a]P) were found to be intermediate between those of the two parental strains. Mutational activation of the K-ras gene was found at a high frequency in both the B[a]P- and DMN-induced C3A lung tumors. To explore the genetic basis of the K-ras gene involvement in mouse lung tumor susceptibility, the parental origin of the K-ras oncogene in the chemically induced C3A lung tumors was determined. K-ras oncogenes were found on the allele inherited from the susceptible A/J parent in 14/16 of DMN-induced tumors and 15/17 of B[a]P-induced tumors from C3A mice. Furthermore, the K-ras mRNA transcribed from the A/J allele was 5-20 times more than C3H K-ras transcripts in 10/10 DMN-induced and 10/10 B[a]P-induced C3A lung tumors. These data suggest that an activated A/J K-ras allele could be more tumorigenic than an activated C3H allele due to the differential expression of the two alleles in lung cells.

Alleles↗