Chromosome locations of the MYB related genes, AMYB and BMYB

The MYB related loci, AMYB and BMYB, were localized to specific human chromosome regions by Southern blot analysis of their segregation patterns in a panel of rodent-human hybrid DNAs using radiolabeled AMYB and BMYB probes. The AMYB locus was present in hybrids retaining the chromosome region 8cen----8q22 and was absent in hybrids which had lost this chromosome region. The presence of the BMYB locus in rodent-human hybrids correlated with, and only with, chromosome region Xq13. Chromosomal in situ hybridization refined the localization of AMYB to region 8q22-23 and confirmed the localization of BMYB to region Xq13. Chromosome region 8q22 is involved in recurrent translocations in malignant lymphoma and in acute myeloid leukemia (AML-M2); therefore AMYB is a candidate for involvement in such translocations. A region on Xq13 is also involved in chromosomal abnormalities in acute myeloid leukemia and myelodysplasias.     

Allele-specific methylation analysis on upstream promoter region of H19 by methylation-specific PCR with confronting two-pair primers

H19 and IGF2 genes are imprinted genes and expressed differently depending on whether they are carried by a chromosome of maternal or paternal origin; H19 is expressed only from the maternal allele and IGF2 only from the paternally inherited allele. The upstream promoter region of H19 has the imprinting-control region (ICR) or CTCF binding sites, where the methylation status of this region is critical to the regulation of imprinting of the H19/IGF2 locus located in chromosome 11p15. There are various reports on imprinting disorders in this region. In colorectal cancer aberrant biallelic methylation of CTCF binding site has been reported, and aberrant hypomethylation of this region in bladder cancer. Thus, certain human neoplasms have either hyper- or hypo-methylation in the ICR. Hence it is still difficult to analyze allele-specific methylation disorder of the region, or differentially methylated regions (DMR), locate upstream of H19. Here we report a new method, which could distinguish paternal epigenetic or maternal epigenetic pattern by a single PCR assay, to combine methylation-specific PCR and PCR with confronting two-pair primers (MSP-CTPP). Using this method, we investigated the region close to H19 ICR in 161 colorectal cancer and 65 gastric cancer cases.     

Methylation status of T-cell receptor beta-chain gene in B precursor acute lymphoblastic leukemia: correlation with hypomethylation and gene rearrangement.

Epigenetic changes may play a role in genetic alterations in cancer cells, but little is known about this phenomenon. In this study we examined the correlation between rearrangement and methylation status of the T-cell receptor (TCR) beta-chain gene in 23 patients with B precursor acute lymphoblastic leukemia (ALL). In B precursor ALL, all patients had a CCmeGG sequence in the C beta 2 region, a pattern similar to that observed in normal mature B-cells. Approximately 55% of patients with B precursor ALL exhibiting a hypomethylated CCGG sequence at the J beta 1 region showed rearrangement of this region. Furthermore, the same allele of rearranged J beta 1 always contained an unmethylated sequence in the region, although another allele without rearrangement contained methylated J beta 1. By contrast, none of the patients had a rearrangement in the J beta 1 region without hypomethylation. Therefore, rearrangement of the J beta 1 region may link to the hypomethylation status of this region. A close association between hypomethylation of the J beta 1 region may promote accessibility to a putative common recombinase to produce TCR J beta 1 rearrangement. In contrast, about 45% of patients with a hypomethylated J beta 1 did not show rearrangement in this region, thus allowing categorization of B precursor ALL patients into subtypes, according to the combination of TCR beta-chain gene rearrangement and hypomethylation status, especially in the J beta 1 region.     

Deletion of chromosomal region 13q14.3 in childhood acute lymphoblastic leukemia.

Deletion of the 13q14 chromosomal region is frequent in B cell chronic lymphocytic leukemia (B-CLL) and is believed to inactivate a tumor supressor gene (TSG) next to RB1. We studied microsatellite markers spanning the 13q14 chromosomal region in 138 children with acute lymphoblastic leukemia (ALL). Allelic loss was demonstrated in six cases (4.3%). Deletion did not include RB1 in two cases. In five patients, the deleted region overlapped that described in B-CLL. A sixth patient harbored a smaller deletion, slightly more telomeric than minimal deleted regions reported in B-CLL. Apparent differences in the delineation of the minimal deleted region could be due to the fact that the putative TSG is a very large gene, with some deletions affecting only a part of it. Our present findings suggest that at least some of its exons lie within a region of less than 100 kb more telomeric that previously thought.     

Glioblastoma multiforme of the pineal region

Glioblastoma multiforme (GBMs) tumors are exceedingly rare tumors in the pineal region. We present three cases in which patients presented with a pineal/posterior third ventricular region mass and review all the previously reported cases in the literature. Pineal region GBM seems to be a very aggressive tumor with a high rate of leptomeningeal and ependymal metastatic disease. Patients usually present with signs and symptoms of hydrocephalus and Parinaud’s syndrome. The clinical and radiological characteristics of pineal GBM do not differentiate it from other malignancies of this region, thus surgical biopsy is generally required for definitive diagnosis. Glioblastoma should be considered in the differential diagnosis of the pineal region tumors, especially when evidence of leptomeningeal or ependymal metastatic disease is present.     

Mapping of MAX to human chromosome 14 and mouse chromosome 12 by in situ hybridization.

The protein encoded by the MAX gene is a member of the class of basic region-helix-loop-helix-zipper proteins and has been demonstrated to associate with N-, L-, and c-Myc proteins both in vitro and in vivo. Heterodimers formed between c-Myc and Max proteins have been shown to possess sequence-specific DNA-binding activity. Here we report the mapping of the MAX gene to a single region on human chromosome 14 (bands q22-q24) and to mouse chromosome 12 (region D). Chromosome abnormalities linked to several neoplasms have been previously associated with this region on human chromosome 14. The mapping results also confirm a region of homology between human chromosome 14q22-24 and mouse chromosome 12 region D.     

城市彩色航空影像的边缘模糊Retinex阴影消除

分析了中心 /环绕Retinex算法在阴影消除上的局限性 ,并提出了一种新方法———边缘模糊Retinex ,用于城市彩色航空影像中的阴影消除。首先利用阴影检测算法 ,把图像分割为阴影区域和非阴影区域。然后对阴影边缘进行模糊化。并利用中心 /环绕Retinex算法 ,分别处理模糊化后的图像阴影区域和非阴影区域。最后将结果合并 ,并去模糊。实验表明该方法取得了较好的效果。     

Differences in tumor core distribution between palpable and nonpalpable prostate tumors in patients diagnosed using extensive transperineal ultrasound-guided template prostate biopsy

BACKGROUND: The authors performed extensive transperineal ultrasound-guided template prostate biopsies to investigate carcinoma core distribution. METHODS: Between August 2000 and May 2004, 371 men underwent template biopsies. Three hundred twelve patients had not undergone a previous biopsy (first group) and 59 had undergone previous transrectal sextant biopsies (repeat group). Of the 312 patients in the first group, 236 had normal digital rectal examination (DRE) findings (DRE- first group) and 76 patients had an abnormal DRE (DRE+ first group). A mean of 20.1 biopsy cores (range, 9-38 cores) was taken from the entire prostate. The region > 2.0 cm from the rectal face of the prostate was defined as the anterior region and the remaining area was defined as the posterior region. RESULTS: In the DRE- first group, the carcinoma core rate (number of tumor cores/number of biopsy cores) in the anterior region (7.2%) did not differ from that of the posterior region (7.3%) (P = 0.9635). However, in the DRE+ first group, the carcinoma core rate in the posterior region (22.0%) was found to be higher than in the anterior region (13.2%) (P < 0.0001). In the repeat group, the carcinoma core rate in the posterior region (3.1%) was significantly (P = 0.0008) lower than that exhibited in the anterior region (7.2%). CONCLUSIONS: The results of the current study suggest that nonpalpable prostate carcinoma is distributed equally within the entire prostate, although palpable carcinoma is distributed mainly in the posterior region and many of the tumor foci in the anterior region may be missed by a transrectal sextant biopsy. The examination of radical prostatectomy specimens is required to prove these results.     

Structural organization of a src gene from Xenopus laevis.

By sequence analysis of genomic clones, the exon-intron structure of one of the two src genes from Xenopus laevis has been determined. The coding region of the gene is interrupted by 10 introns whose locations are identical to the introns in the coding regions of the src genes of human and chicken. The 5' untranslated region is contained on a separate exon with no sequence conservation relative to the corresponding region of the chicken gene. The 5' untranslated region of the Xenopus gene contains a G + C-rich stem-loop sequence and two ATG triplets. A 1.4-kb fragment containing the 5' untranslated region and sequences upstream of it acts as a promoter when introduced in the correct orientation into X. laevis cell lines. The DNA sequence of this fragment lacks the typical arrangement of TATA and CCAAT sequences but contains the ATGCAAAT octamer sequence and a (TA)39 sequence.     

Direct sequencing analysis of transmembrane region of human Neu gene by polymerase chain reaction

The neu gene in rat neuro/glioblastoma was found to be activated by a single point mutation in the DNA sequence encoding the transmembrane region of the neu-encoded p185 protein. The human homologue of the rat neu gene, termed c-erbB-2 or HER-2, can also be activated in vitro by a similar mutation in the corresponding region. Although the human neu gene was shown to be amplified/overexpressed in a large portion of human breast and ovarian cancer, no reports indicate that the human neu gene is activated by a point mutation in human tumor. To study the possible point mutation of neu gene in human tumors, we characterized the genomic structure in the transmembrane region of human neu gene, which in turn allowed us to determine DNA sequence in this region directly following DNA amplification by polymerase chain reaction. We analyzed 7 tumor cell lines (2 breast cancer, 1 neuroblastoma, 1 rhabdomyosarcoma, and 3 glioma) and 11 tumor tissue samples (8 breast and 3 ovarian cancers). No mutation was found in the transmembrane region of human neu gene. Our results suggest that unlike the rat neuro/glioblastoma, the single point mutation in the transmembrane region of the human neu gene is a rare event in human tumors. In this study, we developed a technique for direct DNA sequencing of the transmembrane region of the human neu gene. This technique makes it possible to screen a large number of tumor samples.     

Expression mapping at 12p12-13 in advanced prostate carcinoma

We have previously mapped a putative prostate cancer tumor-suppressor gene to a 1-2 Mb region of 12p12-13. Initial work to identify the tumor suppressor at this locus focused on candidates previously implicated in malignancy; however, mutational and methylation analyses failed to identify significant genomic events. An alternative approach is to use expression analysis to prioritize the genes within the region of interest. This experimental design is based on the hypothesis that tumor-suppressor genes demonstrate decreased expression in tumors compared to normals. Herein, we narrow the region of interest using deletion mapping data and employ expression analysis to prioritize the genes in the minimal deleted region. Highly informative polymorphic markers spanning our region were used to assess for loss of heterozygosity in 99 tumor and normal DNA pairs. The minimal region of deletion was determined to be approximately 500 kb bounded by D12S391 and A002Q26. Publically available databases place 7 genes within this minimal deletion region. An additional 3 genes lie just outside this minimal deletion region and could possibly be inactivated by deletion of promoter, 3'-untranslated region sequences or alternative splice variants. Relative levels of expression of these 10 candidate genes were determined in 6 normal prostates, 5 local prostate tumors, 9 prostate lymph node metastases, 6 prostate cancer cell lines and 12 prostate cancer xenografts using quantitative RT-PCR. DUSP16, FLJ10298 and BCLG were significantly downregulated in both clinical tumors and cultured prostate cancer tissue, indicating that one or all may be critical to initiation or progression of prostate carcinoma.     

乳腺癌线粒体基因组控制区突变的研究

目的:通过测定乳腺癌线粒体基因组控制区突变的频率和分布,探讨其在肿瘤发生中的作用。方法:提取30例乳腺癌患者的癌及癌旁正常组织细胞总DNA,PCR扩增线粒体DNA(mitochondrialDNA,mtDNA)基因组控制区D-loop区,单链构象多态性(single-strandconformationpolymorphism,SSCP)筛查突变标本,基因测序分析突变。结果:在30例乳腺癌组织中9例(30%)乳腺癌共发现14个新的突变位点,其中6例在多聚胞嘧啶区(D310区)的311~313位点出现了CC或CCC删除。结论:乳腺癌线粒体DNA显示了高频率的D-loop区的突变,D310区是点突变、插入/缺失突变的热点。D-loop区尤其是D310区的变化在肿瘤的形成中可能扮演了重要角色。     

Endodermal sinus tumor of the pineal region: case report.

This is a case report of an endodermal sinus tumor occurring in the pineal region of a 12-year-old Caucasian boy. Germ cell tumors of this type demonstrate a selective overgrowth of yolk sac endoderm associated with extraembryonic mesoblast and arise perferentially in the gonads of young children. This is the ninth known report of this tumor in the world literature. Its occurrence in the posterior third ventricle again confirms that pineal region germ cell tumors are histologically analogous to germ cell tumors originating in the gonads. A disturbance in the region of the primitive streak is thought to account for the exclusive midline location of this tumor in extragonadal sites. This patient was treated with a combination of vincristine, actinomycin D, and cyclophosphamide, and concomitant cobalt irradiation. For endodermal sinus tumors in the pineal region, this combination appears more effective than previously reported treatment by irradiation alone.     

The functional domain of the stimulatory GDP/GTP exchange protein (smg GDS) which interacts with the C-terminal geranylgeranylated region of rap1/Krev-1/smg p21.

rap1/Krev-1/smg p21 (smg p21), a member of the small GTP-binding protein (G protein) superfamily, has a geranylgeranylated cysteine residue and clustered basic amino acids in the C-terminal region. The GDP/GTP exchange reaction of smg p21 is regulated by smg GDS, which is also active on Ki-ras p21 and rho p21. The C-terminal region of smg p21 is essential for its interaction with smg GDS. Moreover, smg p21 is phosphorylated by cyclic AMP- and cyclic GMP-dependent protein kinases at the serine residue between the polybasic region and the prenylated cysteine residue, and this phosphorylation initiates the smg GDS-induced smg p21 activation. Thus, the C-terminal cationic and hydrophobic region is important for the regulation of the smg p21 activity. In the present study, we attempted to determine the functional domain of smg GDS which interacts with the C-terminal region of smg p21 by use of a cross-link method and a site-directed mutagenesis method. The region of smg GDS cross-linked with the C-terminal region of smg p21B was residues 444-492, which is located at the C-terminal fifth of smg GDS. On deletion of these residues, smg GDS became inactive on smg p21B, Ki-ras p21 and rhoA p21. These results indicate that residues 444-492 of smg GDS are at least one of the domains which interact with the C-terminal region of its substrate small G proteins.