Comparative analysis of loss of heterozygosity of specific chromosome 3, 13, 17, and X loci and TP53 mutations in human epithelial ovarian cancer

The Genetic and Molecular Analyses of RAD51C and RAD51D Identifies Rare Variants Implicated in Hereditary Ovarian Cancer from a Genetically Unique Population

To identify candidate variants in RAD51C and RAD51D ovarian cancer (OC) predisposing genes by investigating French Canadians (FC) exhibiting unique genetic architecture. Candidates were identified by whole exome sequencing analysis of 17 OC families and 53 early-onset OC cases. Carrier frequencies were determined by the genetic analysis of 100 OC or HBOC families, 438 sporadic OC cases and 1025 controls. Variants of unknown function were assayed for their biological impact and/or cellular sensitivity to olaparib. RAD51C c.414G>C;p.Leu138Phe and c.705G>T;p.Lys235Asn and RAD51D c.137C>G;p.Ser46Cys, c.620C>T;p.Ser207Leu and c.694C>T;p.Arg232Ter were identified in 17.6% of families and 11.3% of early-onset cases. The highest carrier frequency was observed in OC families (1/44, 2.3%) and sporadic cases (15/438, 3.4%) harbouring RAD51D c.620C>T versus controls (1/1025, 0.1%). Carriers of c.620C>T (n = 7), c.705G>T (n = 2) and c.137C>G (n = 1) were identified in another 538 FC OC cases. RAD51C c.705G>T affected splicing by skipping exon four, while RAD51D p.Ser46Cys affected protein stability and conferred olaparib sensitivity. Genetic and functional assays implicate RAD51C c.705G>T and RAD51D c.137C>G as likely pathogenic variants in OC. The high carrier frequency of RAD51D c.620C>T in FC OC cases validates previous findings. Our findings further support the role of RAD51C and RAD51D in hereditary OC.

The P72R Polymorphism in R248Q/W p53 Mutants Modifies the Mutant Effect on Epithelial to Mesenchymal Transition Phenotype and Cell Invasion via CXCL1 Expression

High-grade serous carcinoma (HGSC), the most lethal subtype of epithelial ovarian cancer (EOC), is characterized by widespread TP53 mutations (>90%), most of which are missense mutations (>70%). The objective of this study was to investigate differential transcriptional targets affected by a common germline P72R SNP (rs1042522) in two p53 hotspot mutants, R248Q and R248W, and identify the mechanism through which the P72R SNP affects the neomorphic properties of these mutants. Using isogenic cell line models, transcriptomic analysis, xenografts, and patient data, we found that the P72R SNP modifies the effect of p53 hotspot mutants on cellular morphology and invasion properties. Most importantly, RNA sequencing studies identified CXCL1 a critical factor that is differentially affected by P72R SNP in R248Q and R248W mutants and is responsible for differences in cellular morphology and functional properties observed in these p53 mutants. We show that the mutants with the P72 SNP promote a reversion of the EMT phenotype to epithelial characteristics, whereas its R72 counterpart promotes a mesenchymal transition via the chemokine CXCL1. These studies reveal a new role of the P72R SNP in modulating the neomorphic properties of p53 mutants via CXCL1, which has significant implications for tumor invasion and metastasis.

Four and a Half LIM Domains 2 (FHL2) Contribute to the Epithelial Ovarian Cancer Carcinogenesis

Epithelial ovarian cancer (EOC) is one of the most lethal gynecologic malignancies. To date, the etiology of this deadly disease remains elusive. FHL2, a member of the four and a half LIM domain family, has been shown to serve either as an oncoprotein or as a tumor suppressor in various cancers. Our previous study showed that FHL2 plays a critical role in the initiation and progression of ovarian granulosa cell tumor via regulating AKT1 transcription. However, direct and systematic evidence of FHL2 in the initiation and progression of EOC remains unclear. In the present study, immunohistochemical analysis from EOC patient tissues showed that positivity and intensity of FHL2 immunosignal were up-regulated in the EOC tissues compared with normal ovary tissues. Knockdown of FHL2 in SKOV-3 cell line reduced cell growth and cell viability, blocked cell cycle progression, and inhibited cell migration. Ectopic expression of FHL2 in IGROV-1 cells which have low endogenous FHL2, promoted cell growth, improved cell viability and enhanced cell migration. Additionally, knock down of FHL2 in the SKOV-3 cell line significantly inhibited anchorage-independent growth indicated by the soft agar assay. In comparison, overexpression of FHL2 in IGROV-1 cell improved the colonies growth in soft agar. Western blot data showed that knockdown of FHL2 downregulated AKT expression level, and upregulated apoptosis related proteins such as cleaved PARP, and cleaved-lamin A. Finally, by employing stable SKOV-3/FHL2 stable knock down cell line, our data clearly showed that knockdown of FHL2 inhibited EOC xenograft initiation in vivo. Taken together, our results showed that FHL2, via regulating cell proliferation, cell cycle, and adhesion, has a critical role in regulating EOC initiation and progression. These results indicate that FHL2 could be a potential target for the therapeutic drugs against EOC.

ARID1A protein expression is retained in ovarian endometriosis with ARID1A loss-of-function mutations: implication for the two-hit hypothesis

ARID1A loss-of-function mutation accompanied by a loss of ARID1A protein expression is considered one of the most important driver events in endometriosis-associated ovarian cancer. Although our recent genomic study clarified that ARID1A loss-of-function mutations were detected in 13% of ovarian endometriosis, an association between the ARID1A mutation status and ARID1A protein expression in ovarian endometriosis remains unclear. We performed immunohistochemical staining for ARID1A in 78 ovarian endometriosis samples and 99 clear cell carcinoma samples. We revealed that not only 70 endometriosis samples without ARID1A mutations but also eight endometriosis samples with ARID1A loss-of-function mutations retained ARID1A protein expression. On the other hand, most of clear cell carcinomas with ARID1A loss-of-function mutations showed a loss of ARID1A protein expression. In particular, clear cell carcinoma samples which harbor multiple ARID1A loss-of-function mutations or both a single ARID1A loss-of-function mutation and ARID1A allelic imbalance lost ARID1A protein expression. However, ARID1A protein expression was retained in seven clear cell carcinomas with ARID1A loss-of-function mutations. These results suggest that a single ARID1A loss-of-function mutation is insufficient for ARID1A loss in ovarian endometriosis and some clear cell carcinoma. Further driver events may be needed for the malignant transformation of ovarian endometriosis with ARID1A loss-of-function mutations.

Somatic mutations in breast and serous ovarian cancer young patients: a systematic review and meta-analysis

OBJECTIVE

our aim was to evaluate whether somatic mutations in five genes were associated with an early age at presentation of breast cancer (BC) or serous ovarian cancer (SOC).

METHODS

COSMIC database was searched for the five most frequent somatic mutations in BC and SOC. A systematic review of PubMed was performed. Young age for BC and SOC patients was set at ≤ 35 and ≤ 40 years, respectively. Age groups were also classified in < 30 years and every 10 years thereafter.

RESULTS

twenty six (1,980 patients, 111 younger) and 16 studies (598, 41 younger), were analyzed for BC and SOC, respectively. In BC, PIK3CA wild type tumor was associated with early onset, not confirmed in binary regression with estrogen receptor (ER) status. In HER2-negative tumors, there was increased frequency of PIK3CA somatic mutation in older age groups; in ER-positive tumors, there was a trend towards an increased frequency of PIK3CA somatic mutation in older age groups. TP53 somatic mutation was described in 20% of tumors from both younger and older patients; PTEN, CDH1 and GATA3 somatic mutation was investigated only in 16 patients and PTEN mutation was detected in one of them. In SOC, TP53 somatic mutation was rather common, detected in more than 50% of tumors, however, more frequently in older patients.

CONCLUSION

frequency of somatic mutations in specific genes was not associated with early-onset breast cancer. Although very common in patients with serous ovarian cancer diagnosed at all ages, TP53 mutation was more frequently detected in older women.

Quantitative analysis of cell-free DNA in ovarian cancer

The aim of the present study was to investigate the association between cell-free DNA (cf-DNA) levels and clinicopathological characteristics of patients with ovarian cancer using a branched DNA (bDNA) technique, and to determine the value of quantitative cf-DNA detection in assisting with the diagnosis of ovarian cancer. Serum specimens were collected from 36 patients with ovarian cancer on days 1, 3 and 7 following surgery, and additional serum samples were also collected from 22 benign ovarian tumor cases, and 19 healthy, non-cancerous ovaries. bDNA techniques were used to detect serum cf-DNA concentrations. All data were analyzed using SPSS version 18.0. The cf-DNA levels were significantly increased in the ovarian cancer group compared with those of the benign ovarian tumor group and healthy ovarian group (P<0.01). Furthermore, cf-DNA levels were significantly increased in stage III and IV ovarian cancer compared with those of stages I and II (P<0.01). In addition, cf-DNA levels were significantly increased on the first day post-surgery (P<0.01), and subsequently demonstrated a gradual decrease. In the ovarian cancer group, the area under the receiver operating characteristic curve of cf-DNA and the sensitivity were 0.917 and 88.9%, respectively, which was higher than those of cancer antigen 125 (0.724, 75%) and human epididymis protein 4 (0.743, 80.6%). There was a correlation between the levels of serum cf-DNA and the occurrence and development of ovarian cancer in the patients evaluated. bDNA techniques possessed higher sensitivity and specificity than other methods for the detection of serum cf-DNA in patients exhibiting ovarian cancer, and bDNA techniques are more useful for detecting cf-DNA than other factors. Thus, the present study demonstrated the potential value for the use of bDNA as an adjuvant diagnostic method for ovarian cancer.

The significance of the alteration of 8-OHdG in serous ovarian carcinoma

Background

Oxidative damage and DNA repair dysfunction are associated with carcinogenesis. 8-OHdG is one of the major oxidative DNA adducts. Present work aims to investigate whether the expression of 8-OHdG and its key repair gene hOGG1 play distinctive role in two types of serous ovarian cancer.

Materials and methods

8-OHdG level in DNA from tumor and matched tumor-adjacent normal tissue in 48 high-grade papillary serous carcinomas (HG-SOC), 24 low-grade papillary serous carcinomas (LG-SOC), 20 serous cystadenomas, and 16 non-tumor control ovaries was tested. The Cox proportional hazards model and the log-rank test were used to assess the associations between the 8-OHdG level in two types of serous cancer and patients’ survival. Real-time polymerase chain reaction and protein immunoblot were employed to detect hOGG1 mRNA and protein levels in tumor and adjacent normal tissues. Immunohistochemistry was used to determine the expression of hOGG1 and p53.

Results

There was no difference of average 8-OHdG/10⁶dG DNA level either between HG-SOC (27.8 ± 8.9), LG-SOC (25.2 ± 7.4) and benign serous cystadenoma (26.5 ± 7.7, p = 0.35); or between the tumor-adjacent normal tissue of HG-SOC (18.8 ± 5.2), LG-SOC (21.4 ± 6.5), benign serous cystadenoma (20.5 ± 9.1) and non-tumor ovary (21.6 ± 4.9, p = 0.62). The 8-OHdG/10⁶dG level was significantly higher in tumor comparing to that in matched normal tissue adjacent to carcinoma in HG-SOC (1.52 ± 0.52, p = 0.02), but not in LG-SOC or benign serous cystadenoma. Increased level of 8-OHdG in tumor DNA was an independent factor of overall survival in serous ovarian carcinoma upon multivariate analysis (p < 0.01). Increased level of 8-OHdG in tumor DNA indicates poorer overall and progression-free survival durations than counterparts (47.3 vs 105.7 months and 13.5 vs 45.3 months, respectively). Protein levels of hOGG1 were remarkably decreased in HG-SOC (p < 0.01), but not in LG-SOC and serous cystadenoma compared with the tissue adjacent to carcinoma. A positive result on p53 immunostaining was associated with lower hOGG1 expression in HG-SOC (p = 0.04).

Conclusion

Increased 8-OHdG level and decreased expression of hOGG1 in tumor were found in HG-SOC but not LG-SOC. Increased 8-OHdG level in tumor DNA was significantly associated with poorer overall survival and progression-free survival in serous ovarian carcinoma.

Immunoexpression and prognostic role of p53 in different subtypes of epithelial ovarian carcinoma

We sought to investigate the significance of p53 expression for epithelial ovarian carcinoma. In this study, we used immunohistochemical method to investigate the expression patterns of p53 in different subtypes of epithelial ovarian carcinoma. We found that the expressions of p53 protein in epithelial ovarian cancer (pituita, serosity and intima) were 88.9%, 75% and 100%, respectively, while the recurrence rates among three cancer subtypes were significantly different (33.3%, 12.5% and 0%, respectively; P < 0.05). Compared with patients without lymph node metastasis, the expression of p53 in patients with lymph node metastasis was significantly strong (68.75% and 100%, respectively; P < 0.05). However, the recurrence rate in the patients with lymph node metastasis (40%) was higher than that without lymph node metastasis (6.25%, P < 0.05). The expressions of p53 protein in ovarian cancer between I-II (25%) stage and II-IV stage (100%) were significantly different (P < 0.05), and the recurrence rates between the two groups were significantly different (0% and 31.25%, respectively, P < 0.05). Therefore, p53 protein has an intimate relationship with the malignant degree and the prognosis of ovarian cancer.

VGLL3 expression is associated with a tumor suppressor phenotype in epithelial ovarian cancer

Previous studies have implicated vestigial like 3 (VGLL3), a chromosome 3p12.3 gene that encodes a putative transcription co-factor, as a candidate tumor suppressor gene (TSG) in high-grade serous ovarian carcinomas (HGSC), the most common type of epithelial ovarian cancer. A complementation analysis based on microcell-mediated chromosome transfer (MMCT) using a centric fragment of chromosome 3 (der3p12-q12.1) into the OV-90 ovarian cancer cell line haploinsufficient for 3p and lacking VGLL3 expression was performed to assess the effect on tumorigenic potential and growth characteristics. Genetic characterization of the derived MMCT hybrids revealed that only the hybrid that contained an intact VGLL3 locus exhibited alterations of tumorigenic potential in a nude mouse xenograft model and various in vitro growth characteristics. Only stable OV-90 transfectant clones expressing low levels of VGLL3 were derived. These clones exhibited an altered cytoplasmic morphology characterized by numerous single membrane bound multivesicular-bodies (MVB) that were not attributed to autophagy. Overexpression of VGLL3 in OV-90 was achieved using a lentivirus-based tetracycline inducible gene expression system, which also resulted in MVB formation in the infected cell population. Though there was no significant differences in various in vitro and in vivo growth characteristics in a comparison of VGLL3-expressing clones with empty vector transfectant controls, loss of VGLL3 expression was observed in tumors derived from mouse xenograft models. VGLL3 gene and protein expression was significantly reduced in HGSC samples (>98%, p < 0.05) relative to either normal ovarian surface epithelial cells or epithelial cells of the fallopian tube, possible tissues of origin of HGSC. Also, there appeared to be to be more cases with higher staining levels in stromal tissue component from HGSC cases that had a prolonged disease-free survival. The results taken together suggest that VGLL3 is involved in tumor suppressor pathways, a feature that is characterized by the absence of VGLL3 expression in HGSC samples.

Chromosome 3 anomalies investigated by genome wide SNP analysis of benign, low malignant potential and low grade ovarian serous tumours

Ovarian carcinomas exhibit extensive heterogeneity, and their etiology remains unknown. Histological and genetic evidence has led to the proposal that low grade ovarian serous carcinomas (LGOSC) have a different etiology than high grade carcinomas (HGOSC), arising from serous tumours of low malignant potential (LMP). Common regions of chromosome (chr) 3 loss have been observed in all types of serous ovarian tumours, including benign, suggesting that these regions contain genes important in the development of all ovarian serous carcinomas. A high-density genome-wide genotyping bead array technology, which assayed >600,000 markers, was applied to a panel of serous benign and LMP tumours and a small set of LGOSC, to characterize somatic events associated with the most indolent forms of ovarian disease. The genomic patterns inferred were related to TP53, KRAS and BRAF mutations. An increasing frequency of genomic anomalies was observed with pathology of disease: 3/22 (13.6%) benign cases, 40/53 (75.5%) LMP cases and 10/11 (90.9%) LGOSC cases. Low frequencies of chr3 anomalies occurred in all tumour types. Runs of homozygosity were most commonly observed on chr3, with the 3p12-p11 candidate tumour suppressor region the most frequently homozygous region in the genome. An LMP harboured a homozygous deletion on chr6 which created a GOPC-ROS1 fusion gene, previously reported as oncogenic in other cancer types. Somatic TP53, KRAS and BRAF mutations were not observed in benign tumours. KRAS-mutation positive LMP cases displayed significantly more chromosomal aberrations than BRAF-mutation positive or KRAS and BRAF mutation negative cases. Gain of 12p, which harbours the KRAS gene, was particularly evident. A pathology review reclassified all TP53-mutation positive LGOSC cases, some of which acquired a HGOSC status. Taken together, our results support the view that LGOSC could arise from serous benign and LMP tumours, but does not exclude the possibility that HGOSC may derive from LMP tumours.

Differential subcellular localisation of the tumour suppressor protein LIMD1 in breast cancer correlates with patient survival

The tumour suppressor gene (TSG) LIM domain containing protein 1 (LIMD1) has been associated with transformation of epithelial cells of the lung and its expression is downregulated in all lung tumour samples tested compared to normal lung matched controls. In the first study of its kind we used an anti-LIMD1 specific monoclonal antibody to investigate expression/localisation of the LIMD1 protein in a well-characterised tissue microarray of breast cancers and normal adjacent epithelia. Comparison of tumour with adjacent normal and distant normal tissue demonstrated that LIMD1 expression is moderate to high compared to tumour. There was also a significant correlation with histological grade (p = 0.0001), tumour size (p = 0.013) and tumour type (p = 0.004) indicating an association with aggressive disease. Cytoplasmic LIMD1 expression was seen in 99.3% of cases, with 43.1% showing both nuclear and cytoplasmic localisation. Absence/loss of nuclear staining showed a strong correlation with patient survival and was indicative of poor prognosis (p = 0.033). There was no association with lymph node status and other clinicopathological parameters. Nuclear staining was more pronounced in better prognosis tumours and normal tissue. This study demonstrates that LIMD1 represents a novel prognostic marker for breast cancer. Combined with the fact that LIMD1 expression is downregulated in lung cancers this clearly indicates that LIMD1 may represent a critical TSG, the function of which is deregulated via overall loss of expression and/or relocalisation within the cell during tumour development. The possible functions of LIMD1 localisation within the nucleus and cytoplasm and its relationship to tumour prognosis are discussed.

Construction of a chromosome 17 transcriptome in serous ovarian cancer identifies differentially expressed genes

Cytogenetic, molecular genetic, and functional analyses have implicated chromosome 17 genes in epithelial ovarian cancer (EOC). To further characterize the contribution of chromosome 17 genes in EOC, the Affymetrix U133A GeneChip was used to perform transcriptome analyses of 15 primary cultures of normal ovarian surface epithelial (NOSE) cells and 17 malignant ovarian tumor (TOV) samples of the serous histopathologic subtype. A two-way comparative analysis of 776 known genes and expressed sequences identified 253 genes that exhibited at least a threefold difference in expression in at least one TOV sample compared to the mean of NOSE samples. Within this data set, 99 of the 253 (39.1%) genes exhibited similar patterns of expression across all tested samples, suggesting a high degree of concordance in the chromosome 17 transcriptome. This observation was supported by hierarchical clustering analysis that segregated the TOV and NOSE samples into two separate groups. There were 77 genes that were differentially expressed in at least 50% of the TOV samples. Five genes (AdoRA(2B)at 17p12, CCL2 at 17q12, ACLY at 17q21.2, WIPI1 at 17q24.2, and SLC16A3 at 17q25.3) were significantly (P < 5.13E-11) differentially expressed at least threefold in all serous TOV samples, and all five genes were underexpressed in these TOV samples as compared to the NOSE samples. Interestingly, several of these differentially expressed genes have been previously associated with response to hypoxia.

Comparative proteome analysis of human epithelial ovarian cancer

Background

Epithelial ovarian cancer is a devastating disease associated with low survival prognosis mainly because of the lack of early detection markers and the asymptomatic nature of the cancer until late stage. Using two complementary proteomics approaches, a differential protein expression profile was carried out between low and highly transformed epithelial ovarian cancer cell lines which realistically mimic the phenotypic changes observed during evolution of a tumour metastasis. This investigation was aimed at a better understanding of the molecular mechanisms underlying differentiation, proliferation and neoplastic progression of ovarian cancer.

Results

The quantitative profiling of epithelial ovarian cancer model cell lines TOV-81D and TOV-112D generated using iTRAQ analysis and two-dimensional electrophoresis coupled to liquid chromatography tandem mass spectrometry revealed some proteins with altered expression levels. Several of these proteins have been the object of interest in cancer research but others were unrecognized as differentially expressed in a context of ovarian cancer. Among these, series of proteins involved in transcriptional activity, cellular metabolism, cell adhesion or motility and cytoskeleton organization were identified, suggesting their possible role in the emergence of oncogenic pathways leading to aggressive cellular behavior.

Conclusion

The differential protein expression profile generated by the two proteomics approaches combined to complementary characterizations studies will open the way to more exhaustive and systematic representation of the disease and will provide valuable information that may be helpful to uncover the molecular mechanisms related to epithelial ovarian cancer.

Molecular biomarkers for cancer detection in blood and bodily fluids

Cancer is a major and increasing public health problem worldwide. Traditionally, the diagnosis and staging of cancer, as well as the evaluation of response to therapy have been primarily based on morphology, with relatively few cancer biomarkers currently in use. Conventional biomarker studies have been focused on single genes or discrete pathways, but this approach has had limited success because of the complex and heterogeneous nature of many cancers. The completion of the human genome project and the development of new technologies have greatly facilitated the identification of biomarkers for assessment of cancer risk, early detection of primary cancers, monitoring cancer treatment, and detection of recurrence. This article reviews the various approaches used for development of such markers and describes markers of potential clinical interest in major types of cancer. Finally, we discuss the reasons why so few cancer biomarkers are currently available for clinical use.

Transfer of chromosome 3 fragments suppresses tumorigenicity of an ovarian cancer cell line monoallelic for chromosome 3p

Multiple chromosome 3p tumor suppressor genes (TSG) have been proposed in the pathogenesis of ovarian cancer based on complex patterns of 3p loss. To attain functional evidence in support of TSGs and identify candidate regions, we applied a chromosome transfer method involving cell fusions of the tumorigenic OV90 human ovarian cancer cell line, monoallelic for 3p and an irradiated mouse cell line containing a human chromosome 3 in order to derive OV90 hybrids containing normal 3p fragments. The resulting hybrids showed complete or incomplete suppression of tumorigenicity in nude mouse xenograft assays, and varied in their ability to form colonies in soft agarose and three-dimensional spheroids in a manner consistent with alteration of their in vivo tumorigenic phenotypes. Expression microarray analysis identified a set of common differentially expressed genes, such as SPARC, DAB2 and VEGF, some of which have been shown implicated in ovarian cancer. Genotyping assays revealed that they harbored normal 3p fragments, some of which overlapped candidate TSG regions (3p25-p26, 3p24 and 3p14-pcen) identified previously in loss of heterozygosity analyses of ovarian cancers. However, only the 3p12-pcen region was acquired in common by all hybrids where expression microarray analysis identified differentially expressed genes. The correlation of 3p12-pcen transfer and tumor suppression with a concerted re-programming of the cellular transcriptome suggest that the putative TSG may have affected key underlying events in ovarian cancer.

3p21.3 tumor suppressor cluster: prospects for translational applications

Chromosomal abnormalities at the 3p21.3 region, including homozygous deletions and loss of heterozygosity and expressional deficiencies in 3p21.3 genes including transcriptional silences by promoter hypermethylation, altered mRNA splicing and aberrant transcripts, and lost or defect protein translation and post-translational modifications, are frequently found in most human cancers. Inactivation of 3p21.3 genes in primary tumors affects a wide spectrum of key biological processes such as cell proliferation, cell cycle kinetics, signaling transduction, ion exchange and transportation, apoptosis and cell death, and demonstrates the molecular signatures of carcinogenesis. Restoration of defective 3p21.3 genes with several wild-type 3p21.3 genes suppresses tumor cell growth both in vitro and in vivo. These findings suggest several 3p21.3 genes as potential tumor suppressors and implicates these 3p21.3 genes for future development as biomarkers for the early detection and diagnosis of cancer, and as prognostic and therapeutic tools for cancer prevention and molecular cancer therapy.

Loss of heterozygosity on the X chromosome is an independent prognostic factor in ovarian carcinoma

BACKGROUND

Ovarian carcinoma (OC) is the fifth most frequent female cancer type and the fourth most frequent cause of death from cancer among women in Denmark. At the time they are diagnosed with OC, approximately 70% of patients have advanced disease. It is believed that loss of tumor suppressor gene activity plays an important role in the origin and progression of OC and other malignancies. Loss of heterozygosity (LOH) may be detected in individuals heterozygous for an allele and is associated with loss of function of tumor suppressor genes.

METHODS

The polymorphic marker regions (TP53, CACNLB1, D18S58, DXS538, and DXS454) were amplified by polymerase chain reaction followed by separation using gel electrophoresis before LOH was identified. In total, 160 women with primary epithelial OC were included in the study.

RESULTS

Univariate analyses showed significant differences in survival between patients who had advanced OC with LOH or with retention using the microsatellite markers DXS454 (P = 0.04) and DXS538 (P = 0.01). Multivariate Cox regression analysis that included all patients showed that DXS454 (relative hazard [RH] = 3.5; P = 0.002; 95% confidence interval [95% CI], 1.6-7.8), radicality of primary surgery (RH = 5.5; P < 0.0001; 95% CI, 2.7-11.1), and serum tetranectin level (RH = 0.8; P = 0.009; 95% CI, 0.7-0.9) were independent prognostic factors for survival. Multivariate Cox regression analysis restricted to patients with International Federation of Obstetrics and Gynecology Stage III-IV disease showed that DXS454 (RH = 3.4; P = 0.007; 95% CI, 1.4-8.1), radicality of primary surgery (RH = 5.4; P < 0.0001; 95% CI, 2.2-12.9), and serum tetranectin level (RH = 0.8; P = 0.042; 95% CI, 0.7-1.0) were independent prognostic factors.

CONCLUSIONS

LOH at DXS454 (Xq21-q23) appeared to be correlated with reduced survival in patients with OC.

Detection of genetic alterations in Korean ovarian carcinomas by degenerate oligonucleotide primed polymerase chain reaction-comparative genomic hybridization

Chromosomal aberrations in 22 Koreans with ovarian carcinomas were investigated by degenerate oligonucleotide primed-polymerase chain reaction comparative genomic hybridization. The common sites of copy number increases were 20q (90%), 17q23 approximately qter (86%), 8q22 approximately qter (68%), 3q25 approximately qter (59%), 6p21 (59%), 11q13 (54%), 16p (40%), 2q31 approximately qter (36%), 7q (36%), 14q31 (36%), 15q24 approximately qter (36%), and 1q32 approximately qter (31%). DNA amplification was identified in 18 carcinomas (82%). The frequent sites of amplification were 20q13.2 approximately qter, 8q24.1, 17q23 approximately qter, 3q25 approximately qter, and 6p21. The most frequent sites of copy number decreases were 4q21 approximately q31 (54%), 5q13 approximately q21 (50%), and 13q14 approximately q21 (45%). The recurrent gains and losses of chromosomal regions identified in this study provide candidate regions that may contain oncogenes or tumor suppressor genes, respectively.

Loss of heterozygosity of the VHL gene identifies malignancy and predicts death in follicular thyroid tumors

BACKGROUND

Follicular thyroid tumors (FTT) usually require resection to distinguish adenoma from carcinoma. Better markers that predict histologic subtype and prognosis are needed for FTT.

METHODS

Seventeen benign and malignant FTT with follow-up were selected. Pathologic diagnosis was confirmed, tumor and normal tissue were microdissected, and DNA was extracted. Polymerase chain reaction (PCR) products for a microsatellite marker at the von Hippel Lindau gene (VHL) gene locus (3p26) were analyzed with semiquantitative capillary gel electrophoresis to detect loss of heterozygosity (LOH). Data were assessed for statistical significance with chi(2).

RESULTS

Mean follow-up was 77 months (range 29 to 120 months). Four cases were uninformative (homozygous microsatellite). Among 13 evaluable patients (6 adenomas, 7 follicular cancers) LOH of VHL was present only in carcinomas (P=.013). LOH was present in 4/4 patients with recurrence and 0/3 patients without recurrence (P=.017). Death from disease has occurred in 3 patients. LOH of VHL was strongly associated with death from disease (P=.034).

CONCLUSIONS

FTT can be analyzed for LOH at the VHL gene locus. In this initial study, LOH of VHL was highly specific for malignancy and predicted death from disease. The analysis of VHL may provide for preoperative detection in cytologic samples with potential impact on clinical management of FTT.

Novel perspective: focusing on the X chromosome in reproductive cancers

In an XX female, one of the two X chromosomes has been inactivated during early embryonic life to achieve a compensation of X-linked gene products between males and females, leaving only one allele of X-linked genes functional. There are some X-linked genes escaping the X-inactivation, i.e., being expressed from both alleles. Escape from X-inactivation varies at different levels; some genes have both alleles active in some women but only one allele active in others, whereas some other genes have both alleles active in neoplastic tissue but only one allele active normally. The X-inactivation may be considered functionally equivalent to a loss of heterozygosity (LOH) for some genes, whereas escape from X-inactivation may be equivalent to functional gene amplification for others. The physiological LOH may make X-linked tumor suppressor genes lose their function more easily, compared with autosomal tumor suppressor genes, thus predisposing women to cancer formation more easily. Moreover, the human X chromosome contains many genes related to cancer or to sex and reproduction. All these properties of the X chromosome suggest that it may play more important roles than any autosomal chromosome in the development and progression of reproductive and urologic cancers.