Allelic imbalance at chromosome region 11q23 in cervical carcinomas

The long arm of chromosome 11 has received much scrutiny as a high frequency of deletions of various sites has been observed in different tumour types, indicating the presence of putative tumour suppressor genes. In the present study, 81 primary cervical carcinomas were examined for allelic imbalance (AI) using nine microsatellite markers, mapping to the chromosomal region 11q23.1 where the ATM gene is located. AI at any locus in the region was found in 34 of 81 (42%) tumours. AI frequencies varied from 12 to 31% for the different markers used, with the highest frequency at marker D11S1294. Based on the findings of 17 cases with restricted areas of deletions, four chromosomal regions of possible importance in cervical carcinomas could be distinguished. The first region is located between the markers D11S1325 and D11S1819, the second region between D11S2179 and D11S1294, the third region between D11S1778 and D11S1818 and the fourth region between D11S1818 and D11S1347. The second region may thus contain part of the ATM gene. No association between AI of any marker and histopathological or clinical parameters was seen. When comparing the AI findings of the different loci with TP53 protein overexpression, the only significant association found was with D11S2179 located within the ATM gene. The results indicate that a tumour suppressor gene (or genes) on chromosome 11q.23.1 may be involved in carcinogenesis of the cervix and the involvement of the ATM gene remains a possibility.     

Frequent amplification of chromosomal region 20q12-q13 in ovarian cancer.

DNA amplification at chromosomal region 20q12-q13, which is common in breast cancer, has recently been described also in ovarian tumors. We studied the amplification of the recently identified candidate oncogenes in this region in 24 sporadic, 3 familial and 4 hereditary ovarian carcinomas, and in 8 ovarian cancer cell lines. High-level amplification of at least one of the five nonsyntenic regions at 20q12-q13.2 was found in 13 sporadic (54%) and in all four hereditary tumors. Typically, two or more distinct amplicons (separated by nonamplified DNA) were found coamplified in various combinations. The regions defined by the AIB1 and PTPN1 genes (at 20q12 and 20q13.1, respectively) were amplified in 25% and 29% of the sporadic tumors, also without simultaneous coamplification of other regions. Amplification of AIB1 (a steroid receptor coactivator gene) was associated with estrogen receptor positivity in sporadic ovarian carcinomas (P = 0.01) and showed a tendency to correlate with poor survival of patients. Of the genes amplified in breast cancer, the BTAK gene was amplified in 21%, the MYBL2 gene in 17%, and the ZNF217 gene in 12.5% of the sporadic tumors. The high frequency of gene amplification at 20q12-q13.2 suggests that the genes amplified therein may play a central role in the pathogenesis of sporadic and hereditary ovarian carcinoma.     

Chromosome 17q25 genes, RHBDF2 and CYGB, in ovarian cancer

It has been proposed that the frequent loss of heterozygosity (LOH) of an entire chromosome 17 contig in epithelial ovarian cancers (EOC) is the consequence of the inactivation of multiple tumour suppressor genes on this chromosome. We report the characterization of a 453 Kb 17q25 locus shown previously to exhibit a high frequency of LOH in EOC samples. LOH analysis further defined the minimal region of deletion to a 65 Kb interval flanked by D17S2239 and D17S2244, which contains RHBDF2, CYGB and PRCD as tumour suppressor gene candidates. Tissue specific expression excluded PRCD as a candidate. RHBDF2 was expressed at low levels in the majority of benign and low malignant potential (LMP) tumours, and in a subset of malignant ovarian tumour samples, as compared with primary cultures of normal ovarian surface epithelial cell (NOSE) samples. CYGB was expressed at low levels in the majority of LMP and malignant samples compared with benign and NOSE samples. In contrast to CYGB expression, RHBDF2 was expressed at low or undetectable levels in EOC cell lines exhibiting tumourigenic characteristics and up-regulated in a genetically modified EOC cell line rendered non-tumourigenic. DNA sequence analysis identified variants but no apparent deleterious mutations in either gene. Methylation-specific PCR analysis suggested that promoter methylation of CYGB but not RHBDF2 occurred in 6 of 31 malignant samples. The results combined suggest that RHBDF2 and CYGB may play distinctive roles in ovarian cancer and could be added to the growing roster of chromosome 17 genes implicated in this disease.     

Allelic imbalance of chromosome 6q in ovarian tumours.

Previous work has implicated putative tumour-suppressor (ts) genes at 6q27 and a broad region at 6p12-q23. Here we report the results of a coded, randomised study of allelic imbalance at 12 loci on 6q on 40 pairs of coded tumour-blood pairs from patients with ovarian tumours. Our results provide clear evidence for the involvement of different regions of 6q in tumours of different histological subtypes. The involvement in serous tumours of a ts gene at the distal site is confirmed. However, proximal 6q presents a complex picture, with possibly three further ts genes: one at 6q21-23.3 involved at high frequency in benign and endometrioid tumours, another at 6q14-q15, also involved in endometrioid tumours, and a third suggested by a smallest region of deletion at 6q16.3-q21, between D6S275 and D6S300, that appears to be involved in early stage tumours. These observations point the way to a statistical study of the involvement of 6q in tumours of different histological type and staging performed on larger cohorts of samples.     

Suppression of tumorigenicity in human ovarian cancer cell lines is controlled by a 2 cM fragment in chromosomal region 6q24-q25

Multiple distinct regions of chromosome 6 are frequently affected by losses of heterozygosity in primary human ovarian carcinomas. We introduced a normal human chromosome 6 into HEY and SKOV-3 ovarian carcinoma cell lines using microcell-mediated chromosome transfer techniques to further investigate the role of this chromosome in ovarian tumorigenesis. The exogenous chromosome was stably propagated in the recipient cells based on fluorescence in situ hybridization (FISH) analyses with a chromosome 6 painting probe. The tumorigenicity of HEY and SKOV-3 cells was completely suppressed after transfer of chromosome 6, but not after transfer of a chromosome 11q13-qter fragment used as control. Using 46 polymorphic microsatellite markers, the region bounded by D6S1649 and D6S1564 was found to be commonly deleted in HEY: chromosome 6 tumorigenic revertant clones. The boundaries of the commonly deleted region could be further narrowed down to a 2 cM (based on the Whitehead genetic map) or 0.36 megabase (based on gdb mapping data) region between D6S1637 and D6S1564 after transferring the exogenous chromosome from revertants into mouse L cells and performing allelic deletion mapping studies against this mouse background. We conclude that this region contains a tumor suppressor gene important for the control of ovarian tumor development.     

Identification of a candidate oncogene SEI-1 within a minimal amplified region at 19q13.1 in ovarian cancer cell lines

High-level amplification of DNA sequence at 19q13.1 is one of the frequent genetic alterations in ovarian cancer. In an attempt to verify the minimal amplified region (MAR) at 19q13.1 and to identify the target oncogenes, 49 probes within a region from D19S425 to D19S907 ( approximately 19.5 cM) were used to survey the amplification status in four ovarian cancer cell lines that have been confirmed as containing amplification at 19q13.1. Two separated overlapping MARs, MAR1 (approximately 200 kb) and MAR2 (approximately 1.1 Mb), were identified at 19q13.1. Two candidate oncogenes, AKT2 and SEI-1, were identified in MAR2. Amplification and overexpression of these two genes in four ovarian cancer cell lines were confirmed by Southern and Northern blot analyses. The proliferation-related function of AKT2 and SEI-1 suggests that both genes are likely to be biological targets of an amplification event at 19q13.1 in ovarian cancer and to play important roles in ovarian tumorigenesis.     

KIF14 is a candidate oncogene in the 1q minimal region of genomic gain in multiple cancers

Gain of chromosome 1q31-1q32 is seen in >50% of retinoblastoma and is common in other tumors. To define the minimal 1q region of gain, we determined genomic copy number by quantitative multiplex PCR of 14 sequence tagged sites (STSs) spanning 1q25.3-1q41. The most frequently gained STS at 1q32.1 (71%; 39 of 55 retinoblastoma) defined a 3.06 Mbp minimal region of gain between flanking markers, containing 14 genes. Of these, only KIF14, a putative chromokinesin, was overexpressed in various cancers by real-time RT-PCR. KIF14 mRNA was expressed in 20/22 retinoblastoma samples 100-1000-fold higher than in retina (t-test P=0.00002); cell lines (n=10) had higher levels than tumors (n=12) (P=0.009). KIF14 protein was overexpressed in retinoblastoma tumors and breast cancer cell lines by immunoblot. KIF14 was expressed in 4/4 breast cancer cell lines 31-92-fold higher than in normal breast tissue, in 5/5 medulloblastoma cell lines 22-79-fold higher than in fetal brain, and in 10/22 primary lung tumors 3-34-fold higher than in normal lung. Patients with lung tumors that overexpress KIF14 showed a trend toward decreased survival. KIF14 may thus be important in oncogenesis, and has promise as a prognostic indicator and therapeutic target.     

Translocation (13;17)(q14;q25) as a novel chromosomal abnormality in acute myeloid leukemia-M4

We report a case of AML-M4 in which G-band karyotyping revealed a previously unreported t(13;17)(q14;q25) in metaphase preparations. The breakpoints at 13q14 and 17q25 are associated with poor prognosis. The MSF and FKHR genes are located on 17q25 and 13q14, respectively. This report of AML-M4 harboring t(13;17)(q14;q25) as a unique cytogenetic abnormality provides more data on the leukomogenesis with rearrangements related with 13q14 and 17q25.     

Comparison between serous and non-serous ovarian cancer as a prognostic factor in advanced epithelial ovarian carcinoma after primary debulking surgery

Background  

Residual tumor size after primary surgery is the most important prognostic factor in advanced ovarian cancer. We conducted a retrospective study in Japanese women to evaluate the association of various residual disease diameters and histological subtypes with overall survival (OS) in patients with residual disease ≥1 cm.     

Decreased expression of gene cluster at chromosome 1q21 defines molecular subgroups of chemoradiotherapy response in esophageal cancers.

PURPOSE: Resistance to preoperative chemoradiotherapy (CTXRT) in 75% of patients with esophageal adenocarcinoma (EAC) underscores the need for identification of biomarkers of CTXRT response. We previously noted an association between decreased expression of epidermal differentiation complex (EDC) genes S100A2 and SPRR3 at chromosome 1q21 and CTXRT resistance. In the current study, we did an in-depth investigation of the expression of 1q21-1q25 region genes to uncover the role of the EDC and its flanking genes in CTXRT response. EXPERIMENTAL DESIGN: We compared 19 pretreatment EAC specimens with normal squamous mucosa for the expression of 517 genes at chromosome 1q21-1q25 and selected target genes based on their differential expression. Using the pathologic complete-response (pathCR) status of the resected specimens as a representation of CTXRT sensitivity, we assessed the association between the expression of target genes and CTXRT response and clinical outcomes. RESULTS: On the basis of the expression levels of IVL, CRNN, NICE-1, S100A2, and SPPR3, genes within and in close proximity to the EDC, cancers were segregated into high (subgroup I) or low (subgroup II) expressers. Four of the five pathCRs were high expressers. Thus, low expressers, with one exception, were all nonresponders. Patients in subgroup I also had longer survival than those in subgroup II, although this result was not statistically significant owing to the small study number. CONCLUSIONS: The expression levels of genes mapping within and close to the EDC define CTXRT response subgroups in EACs.     

Frequent allelic imbalance on chromosome 18q21 in early superficial colorectal cancers.

Genetic alterations in early superficial colorectal cancers have rarely been reported. In the present study, we searched for alterations in the APC and p53 genes in 27 superficial (20 depressed and 7 elevated) and 21 protruding colorectal cancers with submucosal invasion by means of PCR-single strand conformation polymorphism. Allelic imbalance (AI) on five loci, i.e., 1p34-36, 8p21-22, 14q32, 18q21 and 22q12-13, was also analyzed. Since a high incidence of 18q21 AI was detected in the superficial depressed cases, we further screened for alterations in Smad2, Smad4 and DCC. APC alterations were observed in three superficial depressed, one superficial elevated, and 11 protruding colorectal cancers, indicating that the frequency of APC alterations in superficial depressed cases was significantly lower than that in the protruding ones. There was no significant association between p53 alterations and macroscopic types. AI on 18q21 (13/20, 65%) was much higher than those on the other four loci in the superficial depressed cases. Moreover, the frequency of 18q21 AI in the superficial depressed cases was significantly higher than that in the protruding ones. Smad4 alterations were only detected in 1 of the 13 superficial depressed and 3 of the 17 protruding cases, while Smad2 and DCC alterations were not detected in any case examined. These data suggest that the carcinogenetic pathways of protruding and superficial depressed colorectal cancers are different, and that alterations of tumor suppressor gene(s) located on 18q21 other than Smad2, Smad4 and DCC might be associated with most superficial depressed colorectal cancers.     

染色体11q13区FGF3基因在卵巢上皮性肿瘤中的表达与扩增

背景与目的：人类染色体11q13区存在FGF3和cyclinD1等多个癌基因；然而，FGF3基因在卵巢上皮性肿瘤中的异常及其作用，目前仍不清楚。本研究旨在探讨卵巢上皮性肿瘤中FGF3基因的表达与扩增及其临床病理学意义。方法：应用免疫组化和荧光原位杂交方法，检测FGF3在30例卵巢腺瘤、20例卵巢交界性肿瘤和80例卵巢癌中的表达与扩增情况，结合肿瘤的临床病理学资料，分析它们之间的相关性。结果：免疫组化结果显示，全部卵巢良性腺瘤和交界性肿瘤呈FGF3蛋白阴性反应；16％（13／80）的卵巢癌出现FGF3阳性表达，而且卯巢癌中FGF3蛋白表达与肿瘤FIGO分期有显著的相关性（P〈0．05），其中23％的FIGOⅢ／Ⅳ期的卵巢癌出现FGF3蛋白阳性表达，其阳性率明显高于FIGOⅠ／Ⅱ期的肿瘤（4％，P=0．037）：FISH结果显示，只有1％的卵巢癌出现FGF3基因扩增；卵巢交界性肿瘤和良性腺瘤均未观察到FGF3基因的扩增。结论：FGF3蛋白表达可以作为判断卵巢上皮性肿瘤良恶性有参考价值的分子标记；FGF3蛋白表达上调可能参与了部分卵巢癌的浸润转移过程？卵巢上皮性肿瘤中FGF3基因中广增不早其编码蛋白表达上调的主要机制。     

Localization of PS6K to chromosomal region 17q23 and determination of its amplification in breast cancer

The application of comparative genomic hybridization to the analysis of genetic abnormalities in breast carcinoma has consistently revealed that chromosome region 17q22-24 is a frequent site of gene amplification in this type of cancer. As part of an examination of expressed sequence tags for novel amplified genes in this region, we identified PS6K amplifications in both breast tumor tissues and cell lines. PS6K was localized to 17q23 and encodes a serine-threonine kinase whose activation is thought to regulate a wide array of cellular processes involved in the mitogenic response including protein synthesis, translation of specific mRNA species, and cell cycle progression from G1 to S phase. Northern and Western analyses revealed that amplification of this gene was accompanied by corresponding increases in mRNA and protein expression, respectively. These data represent the first determination of a gene amplification within 17q22-24 in breast cancer and suggest an oncogenic activity for PS6K.     

Widespread bimodal intrachromosomal genomic instability in sporadic breast cancers associated with 13q allelic imbalance

Genomic instability is thought to underlie tumor progression in solid tumors, such as breast cancer. Although evidence that the hereditary breast cancer genes, BRCA1 and BRCA2, are involved in DNA repair suggests that genomic instability plays an important role in hereditary breast tumorigenesis, genomic instability remains poorly characterized in sporadic breast cancers. Using a DNA fingerprinting technique, inter-(simple sequence repeat) PCR (inter-SSR PCR), the degree of genomic instability was quantified in 47 sporadic breast cancers compared with matched adjacent normal breast tissues. Almost all sporadic breast cancers show significant genomic instability by inter-SSR PCR. The distribution of this instability is bimodal; 57% of the tumors show fewer changes, whereas 43% show striking genomic alterations. Further analysis of two inter-SSR PCR tumor-normal differences revealed a genomic amplification and probable deletion. Thus, inter-SSR PCR can detect chromosomal breakage-related genomic alterations in most sporadic breast cancers. Genomic instability as detected by inter-SSR PCR is not correlated with aneuploidy, suggesting that this technique preferentially detects intrachromosomal alterations. Chromosomal instability in breast cancer can therefore be subdivided into at least two groups: (a) intrachromosomal and (b) gross chromosomal. Allelic imbalance at markers at the 13q13 and retinoblastoma loci (13q) and not at 17q loci was significantly associated with high levels of intrachromosomal instability, suggesting genes at 13q13 and retinoblastoma loci are either selectively targeted or involved in the genesis of genomic instability in sporadic breast cancers.     

Multisite analysis of high-grade serous epithelial ovarian cancers identifies genomic regions of focal and recurrent copy number alteration in 3q26.2 and 8q24.3

High-grade serous epithelial ovarian cancer (HGS-EOC) is a systemic disease, with marked intra and interpatient tumor heterogeneity. The issue of spatial and temporal heterogeneity has long been overlooked, hampering the possibility to identify those genomic alterations that persist, before and after therapy, in the genome of all tumor cells across the different anatomical districts. This knowledge is the first step to clarify those molecular determinants that characterize the tumor biology of HGS-EOC and their route toward malignancy. In our study, -omics data were generated from 79 snap frozen matched tumor biopsies, withdrawn before and after chemotherapy from 24 HGS-EOC patients, gathered together from independent cohorts. The landscape of somatic copy number alterations depicts a more homogenous and stable genomic portrait than the single nucleotide variant profile. Genomic identification of significant targets in cancer analysis identified two focal and minimal common regions (FMCRs) of amplification in the cytoband 3q26.2 (region α, 193 kb long) and 8q24.3 (region β, 495 kb long). Analysis in two external databases confirmed regions α and β are features of HGS-EOC. The MECOM gene is located in region α, and 15 genes are in region β. No functional data are yet available for the genes in the β region. In conclusion, we have identified for the first time two FMCRs of amplification in HGS-EOC, opening up a potential biological role in its etiopathogenesis.     

Non-polarized expression of Basal-cell adhesion molecule B-cam in epithelial ovarian cancers

The basal cell adhesion molecule (B-CAM) is a M(r) 90,000 cell surface glycoprotein identified by two monoclonal antibodies (mAbs), F8 and G253, raised against human tumor cells. Cloning and sequence analysis of a B-CAM cDNA has revealed a characteristic immunoglobulin domain structure of the B-CAM polypeptide, most closely related to MUC18, a cell surface protein of invasive human melanomas. The pattern of B-CAM expression in cultured cells suggests that the molecule is associated with a substrate-adherent growth pattern in some lineages. Moreover, B-CAM expression is upregulated following malignant transformation in some cell types. In the present study, we have used immunohistochemical methods to examine S-CAM expression in normal and neoplastic tissues, including over 200 tumors of diverse histological type. B-CAM was detected in several normal tissues, including polarized expression in several epithelia and expression in vascular endothelium and smooth muscle. Among the tumors tested, B-CAM was found most uniformly and with a non-polarized pattern in epithelial cancers of the ovary (27 of 31 tumors B-CAM-positive), By contrast, only small subsets of epithelial cancers of other organs, including some neuroendocrine, breast, and lung carcinomas, showed uniform or polarized B-CAM expression. Most non-ovarian carcinomas, lymphomas, sarcomas, and neuroectodermal tumors tested were B-CAM-negative. Immunoprecipitation studies with ovarian carcinoma cell lines showed that B-CAM in these cells is a M, 90,000 glycoprotein, composed of M(r) 65,000-75,000 polypeptides with abundant, N-linked carbohydrate side chains. These findings identify B-CAM as a characteristic cell surface protein of epithelial ovarian cancers. The availability of B-CAM-specific mAbs and cDNAs may help identify the role of B-CAM in normal endothelial and epithelial cells and ovarian cancers.