Impact of next-generation sequencing on the clinical diagnosis of pancreatic cysts

BACKGROUND AND AIMS

The value of next-generation sequencing (NGS) of pancreatic cyst fluid relative to the clinical and imaging impression has not been well-studied. The aim of this study was to assess the impact of NGS on the clinical diagnosis from imaging and carcinoembryonic antigen (CEA) and thus the management of pancreatic cysts.

METHODS

Ninety-two pancreatic cyst fluids from 86 patients were analyzed by cytology, CEA, and targeted NGS. Cysts were classified by imaging as nonmucinous, mucinous, or not specified. NGS results were compared with the imaging impression stratified by CEA and cytology.

RESULTS

NGS impacted the clinical diagnosis by defining a cyst as mucinous in 48% of cysts without elevated CEA levels. The VHL gene in 2 intraductal papillary mucinous neoplasms (IPMNs) supported a serous cystadenoma. Twenty percent of cysts that were nonmucinous by imaging were mucinous by NGS. Of the 14 not-specific cysts, CEA levels were not elevated in 12 (86%), and NGS established a mucinous etiology in 3 (25%). A KRAS or GNAS mutation supported an IPMN with nonmucinous CEA in 71%. A KRAS mutation reclassified 19% of nonneoplastic cysts with nonmucinous CEA as mucinous. Seven cyst fluids (8%) had either a TP53 mutation or loss of CDKN2A or SMAD4 in addition to KRAS and/or GNAS mutations; 5 of 7 (71%) were clinically malignant, and high-grade cytology was detected in all 5. Overall, CEA was more specific for a mucinous etiology (100%), but NGS was more sensitive (86% vs 57%).

CONCLUSIONS

NGS of pancreatic cyst fluid impacts clinical diagnosis and patient management by defining, supporting, or changing the clinical diagnosis based on imaging and CEA. NGS was most valuable in identifying mucinous cysts with nonmucinous CEA. An added benefit is the potential to detect mutations late in the progression to malignancy that may increase the risk classification of the cyst based on imaging and cytology.

GNAS mutation is a frequent event in pancreatic intraductal papillary mucinous neoplasms and associated adenocarcinomas

In contrast to pancreatic ductal adenocarcinomas (PDAs), intraductal papillary mucinous neoplasms (IPMNs) frequently harbour GNAS mutations. To characterise GNAS-mutated pancreatic carcinomas, we examined mutations of GNAS and KRAS in 290 pancreatic adenocarcinomas and 77 pancreatic intraepithelial neoplasias (PanINs). In 64 % (39/61) of IPMNs and 37 % (11/30) of IPMN-associated adenocarcinomas, a GNAS mutation was found. GNAS mutations were frequent (78 %, 7/9) in mucinous carcinomas, with or without associated IPMN. In contrast, GNAS mutations were rarely observed in PDAs (1 %, 1/88) and PanINs (3 %, 2/77), and not at all in mucinous cystic neoplasms (MCNs) (0/10), neuroendocrine neoplasms (0/52), acinar cell neoplasms (0/16), serous cystadenomas (0/10), and solid-pseudopapillary neoplasms (0/14). We found GNAS mutations in 55/91 IPMNs with or without associated invasive carcinoma, solely in intestinal-type (78 %, 21/27) and gastric-type (62 %, 34/55) IPMNs. Of the IPMN-associated adenocarcinomas, mucinous-subtype tumours harboured GNAS mutations more frequently (83 %, 5/6) than tubular-subtype tumours (25 %, 6/24) (p = 0.02). We separately analysed GNAS in the adenocarcinoma and the IPMN component in the IPMN-associated adenocarcinomas. In all mucinous-subtype tumours, the two components exhibited identical genotypes. In contrast, the two components in 8 of 24 tubular-subtype tumours exhibited different genotypes, indicating intratumour heterogeneity. In conclusion, mucinous carcinomas with or without associated IPMN as well as IPMNs frequently harbour a GNAS mutation, reinforcing the notion that these constitute a spectrum of pancreatic tumours. Clinically and pathologically, these tumours are associated, but GNAS mutation sheds further light on this spectrum.

Mammary analogue secretory carcinoma mimicking salivary adenoma

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland tumor characterized by ETV6 translocation. It appears that prior studies have identified MASC by reviewing salivary gland carcinomas, such as acinic cell carcinoma and adenocarcinoma, not otherwise specified. To address the possibility of MASC mimicking benign salivary neoplasms we reviewed 12 salivary gland (cyst)adenomas diagnosed prior to the discovery of MASC. One encapsulated (cyst)adenoma of the parotid gland demonstrated features of MASC. The diagnosis was confirmed by fluorescence in situ hybridization with an ETV6 break-apart probe. An unusual complex pattern of ETV6 rearrangement with duplication of the telomeric/distal ETV6 probe was identified. This case illustrates that MASC may mimic salivary (cyst)adenomas. To more accurately assess true clinical and morphologic spectrum of MASC, future studies may have to include review of salivary (cyst)adenomas. The differential diagnosis of MASC may have to be expanded to include cases resembling salivary (cyst)adenomas.

A combined blood based gene expression and plasma protein abundance signature for diagnosis of epithelial ovarian cancer--a study of the OVCAD consortium

BACKGROUND

The immune system is a key player in fighting cancer. Thus, we sought to identify a molecular 'immune response signature' indicating the presence of epithelial ovarian cancer (EOC) and to combine this with a serum protein biomarker panel to increase the specificity and sensitivity for earlier detection of EOC.

METHODS

Comparing the expression of 32,000 genes in a leukocytes fraction from 44 EOC patients and 19 controls, three uncorrelated shrunken centroid models were selected, comprised of 7, 14, and 6 genes. A second selection step using RT-qPCR data and significance analysis of microarrays yielded 13 genes (AP2A1, B4GALT1, C1orf63, CCR2, CFP, DIS3, NEAT1, NOXA1, OSM, PAPOLG, PRIC285, ZNF419, and BC037918) which were finally used in 343 samples (90 healthy, six cystadenoma, eight low malignant potential tumor, 19 FIGO I/II, and 220 FIGO III/IV EOC patients). Using new 65 controls and 224 EOC patients (thereof 14 FIGO I/II) the abundances of six plasma proteins (MIF, prolactin, CA125, leptin, osteopondin, and IGF2) was determined and used in combination with the expression values from the 13 genes for diagnosis of EOC.

RESULTS

Combined diagnostic models using either each five gene expression and plasma protein abundance values or 13 gene expression and six plasma protein abundance values can discriminate controls from patients with EOC with Receiver Operator Characteristics Area Under the Curve values of 0.998 and bootstrap .632+ validated classification errors of 3.1% and 2.8%, respectively. The sensitivities were 97.8% and 95.6%, respectively, at a set specificity of 99.6%.

CONCLUSIONS

The combination of gene expression and plasma protein based blood derived biomarkers in one diagnostic model increases the sensitivity and the specificity significantly. Such a diagnostic test may allow earlier diagnosis of epithelial ovarian cancer.

A study of the methylation status of opioid binding protein/cell adhesion molecule-like gene in ovarian cancer using nested methylation-specific polymerase chain reaction detection

BACKGROUND

The goal was to improve the methylation-specific PCR (MSP) method and investigate the methylation status of the OPCML gene in carcinoma tissues from ovarian cancer patients.

METHODS

MSP and nested MSP methods were used to examine the methylation status of the OPCML gene promoter in ovarian cancer, borderline tumor, and normal ovary tissues.

RESULTS

Methylation of the OPCML gene was detected in 58.3% (14/24) and 83.3% (20/24) of the specimens from ovarian cancer patients using MSP and nested MSP methods, respectively. No methylation was observed in normal ovarian tissues using either method.

CONCLUSIONS

The modified nested MSP method showed better sensitivity. The methylation of the OPCML gene was significantly higher in ovarian cancer than in normal tissue. The detection of OPCML gene methylation could serve as one of the molecular markers for the diagnosis of ovarian cancer.

Lamin C protein deficiency in the primary fibroblasts from a new laminopathy case with ovarian cystadenoma

BACKGROUND

Laminopathies are a group of rare genetic disorders characterized by multiple-tissue degeneration. We describe a new laminopathy with ovarian cystadenoma and explore its molecular etiology.

METHODS

The case is a 15-year-old girl who presents the prominent progeroid disorders, multiple system degeneration and early-onset cystadenoma of the ovary. Candidate genes including LMNA, ZMPSTE24, PPAR G, INSR and WRN were sequenced to screen for DNA variants. The mRNA and protein expression levels of LMNA were examined in primary fibroblasts. The pathophysiological events such as morphologic alterations, cell senescence, cell proliferation, apoptosis and pRb as well as p53 protein expressions were also investigated in primary fibroblasts.

RESULTS

No mutation was identified in the candidate genes screened. Nuclear abnormalities including nuclear blebs, mislocalization of lamin A/C were evident in the patient fibroblasts. Ultrastructurally, nucleus exhibited nuclear herniation and almost complete loss of peripheral heterochromatin. In addition, lamin C protein expression was markedly reduced whereas lamin A protein level was normal and no prelamin A was detected in the primary fibroblasts. Although the senescence-associated beta-galactosidase staining of patient' cells was negative, cells in S phase increased in accompany with a decrease in pRb protein expression. Furthermore, increases in apoptotic cell death and p53 expression were observed.

CONCLUSIONS

Our data suggest that selective deficiency of lamin C protein is associated with a case of laminopathy with ovarian cystadenoma. The abnormalities in nuclear structure and alterations in gene expression such as the decrease in pRb and increase in p53 may be responsible for the multiple tissue degeneration.

Increased chromosomal stability in cultures of ovarian tumours of low malignant potential compared to cystadenomas

Cell cultures of ovarian cystadenomas transfected with SV40 large T antigen are not immortal because they invariably reach a phenomenon called crisis, which is triggered in part by telomere attrition. Recovery from crisis may be an integral component of the malignant transformation process. We reported earlier that such ovarian cystadenoma cell cultures undergo severe changes in DNA ploidy as they approach crisis and that such changes are an important determinant of crisis independent of telomere attrition. Here, we show that in sharp contrast to these benign ovarian tumours, the DNA content of ovarian tumours of low malignant potential (LMP) was remarkably stable as they approached crisis, suggesting that telomere attrition was the main determinant of this mortality checkpoint. Lack of a ploidy-based crisis was not due to loss of expression of a functional SV40 large T antigen protein. We conclude that ovarian LMP tumours are characterised by increased numerical chromosomal stability compared to cystadenomas. This might account for the fact that most LMP tumours are diploid or near diploid in vivo. This fundamental difference in chromosomal stability between ovarian cystadenomas and LMP tumours also suggests potential differences in predisposition to progression to malignancy between these two ovarian tumour subtypes.

Gene expression analysis of pancreatic cystic neoplasm in SV40Tag transgenic mice model

AIM: To study the gene expression changes in pancreatic cystic neoplasm in SV40Tag transgenic mice model and to provide information about the prevention, clinical diagnosis and therapy of pancreatic cancer.

METHODS: Using the pBC-SV40Tag transgenic mice model of pancreatic cystic neoplasm, we studied the gene expression changes by applying high-density microarrays. Validation of part gene expression profiling data was performed using real-time PCR.

RESULTS: By using high-density oligonucleotide microarray, of 14 113 genes, 453 were increased and 760 decreased in pancreatic cystic neoplasm, including oncogenes, cell-cycle-related genes, signal transduction-related genes, skeleton-related genes and metabolism-related genes. Among these, we confirmed the changes in Igf, Shh and Wnt signal pathways with real-time PCR. The results of real-time PCR showed similar expression changes in gene chip.

CONCLUSION: all the altered expression genes are associated with cell cycle, DNA damage and repair, signal pathway, and metabolism. SV40Tag may cooperate with several proteins in promoting tumorigenesis.

Epididymal cystadenomas and epithelial tumourlets: effects of VHL deficiency on the human epididymis

Although epididymal cystadenomas (ECAs) are among the most frequent VHL disease-associated tumours, fundamental questions about their pathogenesis have remained unanswered. Classification of ECAs is controversial, and the cell of origin is unknown. It is also unknown whether ECAs-like other VHL disease-associated tumours-arise as a result of VHL gene inactivation, and whether ECAs exhibit subsequent activation of hypoxia-inducible factor HIF. Moreover, the morphological spectrum of earliest ECA formation is unknown. In a detailed molecular pathological analysis of a series of epididymides collected from VHL patients at autopsy, we found that ECAs are true neoplasms that arise secondary to inactivation of the wild-type copy of the VHL gene, followed by early and simultaneous activation of HIF1 and HIF2 associated with up-regulation of downstream targets, including CAIX and GLUT-1. The observations also indicate that ECA formation evolves from a variety of microscopic epithelial tumourlets, and that these tumourlets are confined to the efferent ductular system. Although genetic and immunohistochemical analysis of precursor structures consistently revealed VHL gene inactivation and activation of HIF in the precursor lesions, only a small subset appears to progress into frank cystadenoma. Thus, ECA tumorigenesis in VHL disease shares fundamental principles with tumorigenesis in other affected organ systems.

Nuclear–mitochondrial genomic profiling reveals a pattern of evolution in epithelial ovarian tumor stem cells

Analyses of genome orthologs in cancer on the background of tumor heterogeneity, coupled with the recent identification that the tumor propagating capacity resides within a very small fraction of cells (the tumor stem cells-TSCs), has not been achieved. Here, we describe a strategy to explore genetic drift in the mitochondrial genome accompanying varying stem cell dynamics in epithelial ovarian cancer. A major and novel outcome is the identification of a specific mutant mitochondrial DNA profile associated with the TSC lineage that is drastically different from the germ line profile. This profile, however, is often camouflaged in the primary tumor, and sometimes may not be detected even after metastases, questioning the validity of whole tumor profiling towards determining individual prognosis. Continuing mutagenesis in subsets with a mutant mitochondrial genome could result in transformation through a cooperative effect with nuclear genes - a representative example in our study is a tumor suppressor gene viz. cAMP responsive element binding binding protein. This specific profile could be a critical predisposing step undertaken by a normal stem cell to overcome a tightly regulated mutation rate and DNA repair in its evolution towards tumorigenesis. Our findings suggest that varying stem cell dynamics and mutagenesis define TSC progression that may clinically translate into increasing tumor aggression with serious implications for prognosis.

Promoter hypermethylation profile of ovarian epithelial neoplasms

PURPOSE

Ovarian carcinomas are believed to arise de novo from surface epithelium, but the actual molecular pathogenesis is unknown. The aim of this study was to compare the promoter hypermethylation profiles of ovarian epithelial neoplasms to better understand the role of epigenetic silencing in carcinogenesis.

EXPERIMENTAL DESIGN

We analyzed the DNA promoter methylation status of eight tumor suppressor and cancer-related genes (p16, RARbeta, E-cadherin,H-cadherin, APC, GSTP1, MGMT, RASSF1A) in 23 benign cystadenomas, 23 low malignant potential (LMP) tumors, and 23 invasive carcinomas by methylation-specific PCR.

RESULTS

Benign cystadenomas exhibited promoter hypermethylation in only two genes, p16 (13%) and E-cadherin (13%). LMP tumors also showed p16 (22%) and E-cadherin (17%) methylation, in addition to RARbeta (9%) and H-cadherin (4%). All eight genes were hypermethylated in invasive cancers at a frequency of 9% to 30%. The mean methylation index was highest in invasive tumors [0.20 versus 0.065 (LMP) and 0.033 (cystadenomas); P = 0.001]. Promoter methylation of at least one gene was most commonly observed among invasive cancers [78% versus 44% (LMP; P = 0.03) and 26% (cystadenomas; P = 0.0009)]. Three genes exhibited higher methylation frequencies in invasive tumors: RASSF1A (30% versus 0%; P = 0.0002), H-cadherin (22% versus 2%; P = 0.013), and APC (22% versus 0%; P = 0.003).

CONCLUSIONS

Promoter hypermethylation is a frequent epigenetic event that occurs most commonly in invasive epithelial ovarian carcinomas. The profile of aberrant methylation suggests that an accumulation of events at specific genes may trigger malignant transformation of some benign cystadenomas and LMP tumors.

Mitochondrial manganese-superoxide dismutase expression in ovarian cancer: role in cell proliferation and response to oxidative stress

Superoxide dismutases (SODs) are important antioxidant enzymes responsible for the elimination of superoxide radical (O(2)(-)). The manganese-containing SOD (Mn-SOD) has been suggested to have tumor suppressor function and is located in the mitochondria where the majority of O(2)(-) is generated during respiration. Although increased reactive oxygen species (ROS) in cancer cells has long been recognized, the expression of Mn-SOD in cancer and its role in cancer development remain elusive. The present study used a human tissue microarray to analyze Mn-SOD expression in primary ovarian cancer tissues, benign ovarian lesions, and normal ovary epithelium. Significantly higher levels of Mn-SOD protein expression were detected in the malignant tissues compared with normal tissues (p < 0.05). In experimental systems, suppression of Mn-SOD expression by small interfering RNA caused a 70% increase of superoxide in ovarian cancer cells, leading to stimulation of cell proliferation in vitro and more aggressive tumor growth in vivo. Furthermore, stimulation of mitochondrial O(2)(-) production induced an increase of Mn-SOD expression. Our findings suggest that the increase in Mn-SOD expression in ovarian cancer is a cellular response to intrinsic ROS stress and that scavenging of superoxide by SOD may alleviate the ROS stress and thus reduce the simulating effect of ROS on cell growth.

Estrogen enhances whereas tamoxifen retards development of Tsc mouse liver hemangioma: a tumor related to renal angiomyolipoma and pulmonary lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis and abdominal angiomyolipoma are related lesions for which there is no authentic animal model. Both of these proliferative lesions occur in sporadic patients, and at much higher frequency in patients with tuberous sclerosis, which is due to mutations in the TSC1 and TSC2 genes. Tsc1+/- and Tsc2+/- mice frequently develop liver hemangioma. We found that the Tsc mouse liver hemangioma are composed predominantly of endothelial cells but with a smooth muscle component, and express HMB45 antigen, estrogen receptor, and progesterone receptor, similar to lymphangioleiomyomatosis and angiomyolipoma. Estrogen treatment significantly accelerated the development of liver hemangioma in Tsc1+/- female mice, with 91% having liver hemangioma and 55% having severe lesions by 7 months of age. Similarly, an increased frequency and severity of liver hemangiomas was seen in Tsc1+/- males treated with estrogen. In contrast, tamoxifen treatment for 9 months significantly reduced the frequency and severity of hemangiomas in Tsc1+/- female mice. In addition, estrogen treatment significantly increased serum vascular endothelial growth factor levels in Tsc1+/- mice, whereas tamoxifen reduced vascular endothelial growth factor levels. These mouse model observations indicate the importance of estrogen signaling in vivo for the growth of tuberous sclerosis lesions, suggesting the possible benefits of tamoxifen therapy for the treatment of angiomyolipoma and lymphangioleiomyomatosis.

Polo-like kinase isoform expression is a prognostic factor in ovarian carcinoma

The Polo-like kinase (PLK) family comprises three serine/threonine kinases, functionally involved in signal transduction pathways essential for the accomplishment of mitosis in both normal and malignant cells. Moreover, certain PLKs have been functionally linked to cytoskeletal reorganisation. In this study, the expression of PLK1 and PLK3 was determined immunohistochemically in tissue specimen of normal ovaries (n=9), cystadenomas (n=17), borderline tumours (n=13) and ovarian carcinomas (n=77). PLK 1 and PLK3 expression was low in normal ovarian surface epithelium and borderline tumours, with moderately higher expression levels in cystadenomas. In ovarian carcinomas, 26% of cases were PLK1 positive and 50.6% of cases were PLK3 positive. A positive correlation of both PLK1 and PLK3 expression with indicators of mitotic frequency could be established. The overexpression of either isoenzyme had an impact on patient prognosis with shortened survival time for patients with tumours positive for PLK1 (P=0.02) and PLK3 (P=0.02), but only PLK1 expression remained a prognostic factor in multivariate survival analysis (P=0.03). The results of this study, if interpreted in the context of recently published functional data, suggest that inhibition of PLKs might represent an interesting new targeted approach for chemotherapy of epithelial ovarian cancer. Furthermore, this study suggests that PLK1 is a novel independent prognostic marker in ovarian carcinomas.

In situ human telomerase reverse transcriptase expression pattern in normal and neoplastic ovarian tissues

Telomerase is a ribonuclear protein reverse transcriptase that maintains telomere length in eukaryotic cells. Activation of telomerase has been implicated in human cellular immortalization and carcinogenesis. Telomerase activity in ovarian neoplasm has been studied using polymerase chain reaction (PCR)-based methods and shown to be correlated with malignancy. However, we believe those results must be interpreted with caution because such studies used a heterogeneous mix of cells, including normal cell type known to express telomerase when activated. The present study used in situ hybridization that allows determination of the type of cells expressing telomerase, as well as the intensity of that expression, in ovarian neoplasms. A total of 75 specimens were studied. Epithelial telomerase reverse transcriptase mRNA expression was detected in 28 of 31 epithelial ovarian carcinomas, 1 of 1 malignant granulosa cell tumor, 7 of 9 serous borderline ovarian tumors, 11 of 11 mucinous borderline ovarian tumors, 4 of 5 serous cystadenofibromas, 2 of 4 serous cystadenomas, 8 of 8 mucinous cystadenomas, and 0 of 6 normal ovaries except the corpus luteum. Telomerase expression is heterogeneously found in both benign and malignant epithelial tissues. We conclude that human telomerase reverse transcriptase mRNA expression does not seem to be a reliable marker for clinical use in differentiating between benign and malignant tumors.

Ovarian cystadenoma as a characteristic feature of families with hereditary ovarian cancers unassociated with BRCA1 and BRCA2 mutations

The study aimed to determine whether hereditary ovarian cancers that are not caused by BRCA1/BRCA2 constitutional mutations are associated with a predisposition to cystadenoma. The study consisted of two parts. Part one concerned the incidence of ovarian cystadenoma in females from families with hereditary ovarian cancer unassociated with BRCA1 mutations. The study group included 62 female patients from 29 families, without any previously diagnosed malignancy, with no proven constitutional mutation of the BRCA1 gene. The first control group was composed of 62 female patients from 53 families, without any previously diagnosed malignancy, with an identified constitutional mutation of the BRCA1 gene. The second control group comprised 124 female patients for whom the only reason for the examination was a prophylactic check-up. All studied women were subjected to intravaginal ultra- sonographic investigations. In 8 patients with benign and/or borderline ovarian cystadenoma, a complete sequencing of coding fragments of the BRCA2 gene from the peripheral blood DNA was performed. Part two of this study concerned the incidence and pattern of malignant tumors in the families of female patients with ovarian cystadenoma. The final study group included 117 patients who had 726 I0 relatives (359 females and 367 males). We concluded that cystadenoma is likely to be a characteristic feature of the subgroup of families with hereditary ovarian cancers unassociated with BRCA1/BRCA2 constitutional mutations.

Aneuploidy and telomere attrition are independent determinants of crisis in SV40-transformed epithelial cells

Replicative immortality is achieved in vitro by overcoming two mortality checkpoints, M1 (senescence) and M2 (crisis). Cancer cells are thought to overcome M2 by activating telomerase, an enzyme believed to confer genomic stability in addition to maintaining telomeric sequences above a critical length. Here we show that a subset of cultured ovarian cystadenoma cells expressing SV40 large T-antigen, which allows bypassing of M1, develop a specific type of genomic instability, characterized by numerical (as opposed to structural) chromosomal alterations, that leads to non-telomere-based premature growth arrest/crisis. Cells recover from this type of growth arrest and stabilize their ploidy status without telomerase expression. In these cases, telomeres continue to shorten until a second, telomere-based growth arrest/crisis event is reached. Transfection of the catalytic subunit of telomerase does not immortalize cells harboring severe abnormalities in their DNA ploidy but results in immortalization of diploid cells. We conclude that changes in DNA ploidy constitute an important determinant of growth arrest that is independent of telomere attrition in a subset of SV40 large T-antigen-expressing cystadenoma cells. Reestablishment or emergence of ploidy stability, which is not always dependent on telomerase activation, is necessary for acquisition of the potential to achieve replicative immortality.

Analysis of the tumour suppressor genes, FHIT and WT-1, and the tumour rejection genes, BAGE, GAGE-1/2, HAGE, MAGE-1, and MAGE-3, in benign and malignant neoplasms of the salivary glands

AIMS

Molecular genetic changes involved in tumorigenesis and malignant transformation of human tumours are novel targets of cancer diagnosis and treatment. This study aimed to analyse the expression of putative tumour suppressor genes, FHIT and WT-1, and tumour rejection genes, BAGE, GAGE-1/2, MAGE-1, MAGE-3, and HAGE (which are reported to be important in human cancers), in salivary gland neoplasms.

METHODS

Gene expression was analysed by reverse transcription polymerase chain reaction (RT-PCR) in normal salivary gland tissue and 44 benign and malignant salivary gland tumours.

RESULTS

Aberrant FHIT transcripts were found in one of 38 normal salivary glands, three of 28 adenomas, and two of 16 carcinomas. WT-1 mRNA was detectable in two adenomas and five carcinomas. Immunoblotting showed that WT-1 mRNA expression was associated with raised WT-1 protein concentrations. RT-PCR for detection of BAGE, GAGE, and MAGE gene expression was positive in two adenomas and nine carcinomas, but negative in normal salivary gland tissue. HAGE mRNA was found in two normal salivary glands, 11 benign, and eight malignant tumours.

CONCLUSIONS

FHIT mRNA splicing does not appear to be involved in the genesis of salivary gland neoplasms. The upregulation of WT-1 mRNA in tumours of epithelial/myoepithelial phenotype may imply a potential role of WT-1 in the genesis and/or cellular differentiation of these salivary gland tumours. The tumour rejection genes were more frequently, but not exclusively, expressed in malignant salivary gland tumours than in benign neoplasms, although none was suitable as a diagnostic marker of malignancy in salivary gland neoplasms.

Quantitative analysis of follicle-stimulating hormone receptor in ovarian epithelial tumors: a novel approach to explain the field effect of ovarian cancer development in secondary mullerian systems

The role of FSHR expression in ovarian cancer development is not clear. We examined quantitative expression of FSHR in different types of OET, presumed precursor lesions and peritoneal implants and further discussed FSH as a key growth-promotion factor for the process of ovarian epithelial tumorigenesis. Thirty-five primary OET specimens, including 5 serous cystadenomas, 4 papillary serous cystadenomas, 9 SBTs and 17 serous carcinomas, were examined for quantitative FSHR expression. Ten paired samples (3 benign cystadenomas, 5 SBTs and 2 carcinomas) were obtained from several morphologically different areas, including benign-looking, borderline and cancerous areas in the same OETs, and from the remaining ovarian tissue and contralateral ovaries. Competitive RT-PCR was performed to measure the quantitative expression of FSHR in each tissue sample. FSHR expression levels were compared among nonpaired samples and within paired samples. We found that OSE had the lowest FSHR expression, whereas antral follicles had the highest level. Within benign OETs, papillary serous cystadenomas have 4.9-fold higher FSHR levels than nonpapillary serous cystadenomas. SBTs had the highest level of FSHR expression, which was 12.8-fold, 2.7-fold and 2.4-fold higher than that of serous cystadenomas, papillary serous cystadenomas and grade 1 carcinomas, respectively. A similarly high level of FSHR mRNA was found in peritoneal implants, which were associated with SBTs. FSHR levels among serous carcinomas decreased with an increase in carcinoma grade. Grade 3 carcinomas had the lowest FSHR level, which was similar to that of serous cystadenomas, while grade 1 carcinomas had 6.5-fold higher FSHR levels than those in serous cystadenomas. Our results suggest that not only serum FSH but also FSHR in ovarian epithelium may play important roles in ovarian OET development. Both the receptor and ligand may act in a synergistic way to promote tumor growth. The observation that high FSHR levels are present in peritoneal implants suggests that FSH may also play a similar role in the development of peritoneal serous tumors. From this perspective, circulating FSH may be considered a driving force in the field effect theory for the development of both ovarian neoplasms and their associated peritoneal implants. However, the exact role of FSH and/or FSHR in the development of epithelial tumors arising in both the ovary and peritoneum needs further investigation.

A decomposition model to track gene expression signatures: preview on observer-independent classification of ovarian cancer

MOTIVATION

A number of algorithms and analytical models have been employed to reduce the multidimensional complexity of DNA array data and attempt to extract some meaningful interpretation of the results. These include clustering, principal components analysis, self-organizing maps, and support vector machine analysis. Each method assumes an implicit model for the data, many of which separate genes into distinct clusters defined by similar expression profiles in the samples tested. A point of concern is that many genes may be involved in a number of distinct behaviours, and should therefore be modelled to fit into as many separate clusters as detected in the multidimensional gene expression space. The analysis of gene expression data using a decomposition model that is independent of the observer involved would be highly beneficial to improve standard and reproducible classification of clinical and research samples.

RESULTS

We present a variational independent component analysis (ICA) method for reducing high dimensional DNA array data to a smaller set of latent variables, each associated with a gene signature. We present the results of applying the method to data from an ovarian cancer study, revealing a number of tissue type-specific and tissue type-independent gene signatures present in varying amounts among the samples surveyed. The observer independent results of such molecular analysis of biological samples could help identify patients who would benefit from different treatment strategies. We further explore the application of the model to similar high-throughput studies.

Prognostic implications of routine, immunohistochemical, and molecular staging in resectable pancreatic adenocarcinoma

Cure for ductal adenocarcinoma of the pancreas is restricted to resectable tumors, but survival after surgery is still poor. Despite apparently curative resection, these cancers rapidly recur. Thus, the present pathologic examination should be enriched by sensitive methods to detect minimal residual disease. In a prospective setting we studied the frequency of minimal residual disease after curative resection by routine histopathology, immunohistology, and polymerase chain reaction (PCR) for mutated K-ras. Furthermore, the prognostic implication of detecting of MRD was determined. Prospectively, tumor tissue and corresponding paraaortic lymph nodes were obtained from 78 patients, who underwent surgery for pancreatic head tumors between 1999 and 2001. Sixty-nine of 78 cases were diagnosed for ductal adenocarcinoma (study group), whereas nine cases were diagnosed for benign pancreatic tumors (control group). Paraaortic lymph nodes were examined in step sections by routine histopathology (hematoxylin and eosin) and immunohistology using a pan-cytokeratin antibody. DNA of the primary tumor and corresponding paraaortic lymph nodes were analyzed by PCR-based assays with respect to mutated K-ras in codon 12. The recurrence-free survival and overall survival were correlated with the results of the latter methods. In 3 of 69 patients tumor cells were detected in paraaortic lymph nodes by routine histopathology and in 5 of 69 patients by immunohistology. K-ras mutations were detected in 42 of 69 ductal adenocarcinomas (61%), whereas 12 (17%) were positive in paraaortic lymph nodes. All of the latter patients had recurrence after surgery and a significant poorer survival than those without mutated K-ras. Furthermore, paraaortic lymph nodes diagnosed for K-ras mutation were independent prognostic markers in multivariate analysis. In the control group K-ras mutations were detected in one adenoma of Vater's papilla but not in paraaortic lymph nodes. Tumor cell DNA can be detected more sensitively by the described PCR method than with hematoxylin and eosin or immunohistologic staining, leading to a higher sensitivity for detection of micrometastases. The described PCR method clearly determines subgroups of patients after curative resection with early recurrence and poor survival and could therefore enrich the pathologic examination.

A mouse model of TSC1 reveals sex-dependent lethality from liver hemangiomas, and up-regulation of p70S6 kinase activity in Tsc1 null cells

Tuberous sclerosis (TSC) is a autosomal dominant genetic disorder caused by mutations in either TSC1 or TSC2, and characterized by benign hamartoma growth. We developed a murine model of Tsc1 disease by gene targeting. Tsc1 null embryos die at mid-gestation from a failure of liver development. Tsc1 heterozygotes develop kidney cystadenomas and liver hemangiomas at high frequency, but the incidence of kidney tumors is somewhat lower than in Tsc2 heterozygote mice. Liver hemangiomas were more common, more severe and caused higher mortality in female than in male Tsc1 heterozygotes. Tsc1 null embryo fibroblast lines have persistent phosphorylation of the p70S6K (S6K) and its substrate S6, that is sensitive to treatment with rapamycin, indicating constitutive activation of the mTOR-S6K pathway due to loss of the Tsc1 protein, hamartin. Hyperphosphorylation of S6 is also seen in kidney tumors in the heterozygote mice, suggesting that inhibition of this pathway may have benefit in control of TSC hamartomas.

Different imprinting status of IGF-2 in epithelial ovarian tumors

To explore whether the imprinting status of IGF-2 in the malignant epithelial ovarian tumors is different from that in benign tumors, the target sequences (DNA and RNA) which contain a polymorphism site for ApaI restriction endonuclease digestion were amplified with PCR and RT-PCR methods. Then the PCR/RT-PCR products were digested by ApaI. The IGF-2 transcriptional pattern came out from the results of endonucleases digestion. Among the 36 cases of benign epithelial ovarian tumors, 20 were heterozygous for ApaI locus and all showed genomic imprinting. While in the malignant group, 22 were heterozygous for ApaI locus but six were found to lose imprinting. Significant differences existed between the two groups (P < 0.05). Loss of imprinting of IGF-2 may serve as a marker for differentiating the malignant ovarian cancers from the benign ones. In a new field of molecular genetics, our research provides an experimental basis for genetic diagnosis and treatment of the ovarian cancers.

A germ-line Tsc1 mutation causes tumor development and embryonic lethality that are similar, but not identical to, those caused by Tsc2 mutation in mice

Tuberous sclerosis (TS) is characterized by the development of hamartomas in various organs and is caused by a germ-line mutation in either TSC1 or TSC2 tumor suppressor genes. From the symptomatic resemblance among TS patients, involvement of TSC1 and TSC2 products in a common pathway has been suggested. Here, to analyze the function of the Tsc1 product, we established a line of Tsc1 (TSC1 homologue) knockout mouse by gene targeting. Heterozygous Tsc1 mutant (Tsc1(+/-)) mice developed renal and extra-renal tumors such as hepatic hemangiomas. In these tumors, loss of wild-type Tsc1 allele was observed. Homozygous Tsc1 mutants died around embryonic days 10.5-11.5, frequently associated with neural tube unclosure. As a whole, phenotypes of Tsc1 knockout mice resembled those of Tsc2 knockout mice previously reported, suggesting that the presumptive common pathway for Tsc1 and Tsc2 products may also exist in mice. Notably, however, development of renal tumors in Tsc1(+/-) mice was apparently slower than that in Tsc2(+/-) mice. The Tsc1 knockout mouse described here will be a useful model to elucidate the function of Tsc1 and Tsc2 products as well as pathogenesis of TS.

Molecular characterization of pancreatic serous microcystic adenomas: evidence for a tumor suppressor gene on chromosome 10q

Pancreatic serous microcystic adenomas (SCAs) are rare, benign tumors with a striking female preference. Virtually no information is available about chromosomal or genetic anomalies in this disease. We performed extensive molecular characterization of 21 cases of formalin-fixed, paraffin-embedded sporadic SCAs consisting in genome-wide allelic loss analysis with 79 microsatellite markers covering all 22 autosomes, assessment of microsatellite instability, and mutational analysis of the VHL, K-ras, and p53 genes in nine cases for which frozen tissue was available. Although no case showed microsatellite instability of the type seen in mismatch repair-deficient tumors, a relatively low fractional allelic loss of 0.08 was found. Losses on chromosome 10q were the most frequent event in SCAs (50% of cases), followed by allelic losses on chromosome 3p (40% of cases). Moderately frequent losses (>25% of cases) were found on chromosomes 1q, 2q, and 7q. The VHL gene, located on chromosome 3p, had somatic inactivating mutations in two of nine cases (22%), whereas no mutations were found in either K-ras or p53, in agreement with the finding that all 21 cases stained negative for p53 by immunohistochemistry. Our study indicates that the involvement of chromosomal arms 10q and 3p is characteristic of SCAs and that the VHL gene is involved in a subset of sporadic cases.

Decreased luteinizing hormone receptor mRNA expression in human ovarian epithelial cancer

OBJECTIVES

The objective of this study was to examine the distribution and cellular localization of luteinizing hormone receptor (LHR) in ovarian epithelial tumors (OETs) and their presumed precursor lesions-ovarian epithelial inclusions (OEIs). The clinicopathologic correlation of the receptor expression in OET was also examined.

METHODS

Fifteen microdissected samples of ovarian surface epithelium (OSE), 20 OEIs from benign ovaries, and 141 OETs, including 48 cystadenomas, 33 borderline tumors, 60 carcinomas, and 5 metastatic cancers, were examined for LHR expression by using reverse transcription polymerase chain reaction and in situ hybridization. LHR expression in tumor epithelium and tumor stroma was analyzed separately. The clinicopathologic correlation data were analyzed by standard analysis of variance and contingency table methods.

RESULTS

LHR expression was identified in the majority of OSE and OEI samples. In OETs, LHR positivity was found in the epithelial cells in 27% of cases and in the stromal compartment in 37% of cases. LHR-positive stromal cells were mainly luteinized cells. Within the tumor epithelium, LHR expression was detected in 42% of benign, 24% of borderline, and 17% of malignant OETs. LHR expression in tumor stroma showed a similar trend of reduction from benign to malignant OETs. Within the 17 carcinomas, LHR was expressed in the epithelium in 47% of grade 1, 12% of grade 2, and only 5% of grade 3 cancers. The mean age of the LHR-positive group was younger than that of the receptor-negative patients. Compared with mucinous and other types of OETs, serous OETs showed higher LHR expression in the epithelium. Compared with the OETs removed in the different menstrual phases, OETs in the secretory phase showed higher LHR in the tumor stroma than in the proliferative phase. No receptor mRNA was detected in the epithelium of five carcinomas metastatic to the ovary. LHR transcription splicing variants from a single previous report were confirmed in this study.

CONCLUSIONS

Malignant OETs have significant reduction of LHR expression compared with precursor lesions and benign and borderline OETs. LHR expression shows a steady decline from low-grade to high-grade ovarian cancer. The presence of LHR receptor in tumor epithelium suggests that luteinizing hormone in serum may have direct influence on tumor growth, whereas the receptor in tumor stroma may be indicative of a paracrine function of LH in the development of OETs.

Pancreatic involvement in von Hippel-Lindau disease. The Groupe Francophone d'Etude de la Maladie de von Hippel-Lindau

BACKGROUND & AIMS

Pancreatic involvement in von Hippel-Lindau (VHL) disease, a genetic disorder with a dominant mode of inheritance affecting various organs, has rarely been studied. We assessed the prevalence, type of lesions, natural history, and impact of pancreatic involvement in patients with VHL.

METHODS

A total of 158 consecutive patients from 94 families with VHL disease were studied in a prospective French collaborative study. All patients underwent systematic screening for VHL lesions, including computerized tomography (CT) scanning of the pancreas reviewed by an experienced radiologist. Clinical data, investigations, and treatments performed were also reviewed.

RESULTS

Pancreatic involvement was observed in 122 patients (77.2%) and included true cysts (91.1%), serous cystadenomas (12.3%), neuroendocrine tumors (12.3%), or combined lesions (11.5%). The pancreas was the only organ affected in 7.6% of patients. Patients with pancreatic lesions had fewer pheochromocytomas than those without (14/122 vs. 16/36; P<0.0001), and patients with neuroendocrine pancreatic tumors had renal involvement less often than those without (8/99 vs. 6/20; P = 0.013). None of the patients with neuroendocrine tumors had symptoms of hormonal hypersecretion. Pancreatic lesions evolved in half of patients but required specific treatment in only 10 (8.2%) when they were symptomatic or for the resection of large neuroendocrine tumors.

CONCLUSIONS

Pancreatic involvement is seen in most patients with VHL disease. Although symptoms are rare, specific treatment of pancreatic lesions is required in selected patients, mainly those with neuroendocrine tumors.

Detection and clinical correlations of ras gene mutations in human ovarian tumors

In epithelial ovarian neoplasms K-ras codon 12 gene mutations show a wide variation fluctuating between 4-39% in invasive carcinomas and 20-48% in borderline malignant tumors. In this study, we showed the pattern of point mutations in codon 12 of the K-ras, H-ras and N-ras genes, using polymerase chain reaction restriction fragment length polymorphism analysis in 74 tissue specimens of Greek patients with epithelial ovarian tumors. K-ras and H-ras gene mutations were detected in 11/48 (23%) and 3/48 (6%) cases with primary invasive ovarian carcinomas, respectively, while N-ras gene mutations were not found. No mutation of K-, H- and N-ras genes was detected in 23 ovarian cystadenomas. In 1 out of 3 borderline ovarian tumors (33%) we found an H-ras gene mutation. The prevalence of mutations in K-ras gene was 1/8 (13%) in mucinous, 7/29 (24%) in serous, 1/3 (33%) in endometrioid and 2/8 (25%) in clear-cell adenocarcinomas and in H-ras gene 1/8 (13%) in mucinous and 2/29 (7%) in serous adenocarcinomas. Analysis of the results revealed no significant correlation between ras gene mutations and clinicopathological parameters or clinical outcome of this primary invasive ovarian carcinoma population. Our present data suggest that ras gene mutations in invasive ovarian carcinomas occur in 29% of Greek patients and are not associated with the differentiation of the epithelial cells or the response of patients to adjuvant platinum-based chemotherapy.

Differential expression of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 protein and mRNA in epithelial ovarian tumors

OBJECTIVE

Matrix metalloproteinase-9 (MMP-9) can degrade gelatin and type IV collagen and is known to play an important role in tumor cell invasion across the basement membrane. The tissue inhibitor of metalloproteinase-1 (TIMP-1) is able to prevent activation of pro-MMP-9 and forms a 1:1 complex with the active form of MMP-9. The aim of the present study was to investigate the expression of MMP-9 and TIMP-1 in benign, borderline, and invasive epithelial ovarian tumors.

MATERIALS AND METHODS

A total of 90 patients with epithelial ovarian tumor were treated at the Brigham and Women's Hospital and were used as the study population. Immunohistochemistry and in situ hybridization were performed to detect protein and mRNA expression of MMP-9 and TIMP-1.

RESULTS

In the 90 epithelial ovarian tumors tested, MMP-9 expression in tumor cells was found to be significantly enhanced in serous and mucinous ovarian carcinomas compared with benign and borderline tumors. We also observed the immunostaining of MMP-9 in stromal cells of benign, borderline, and invasive epithelial ovarian tumors. Moreover, the expression levels of TIMP-1 in tumor cells were significantly higher in borderline and invasive ovarian tumors than in benign tumors.

CONCLUSION

Using an in situ hybridization technique, we disclosed a direct correlation between the presence of mRNA and protein expression for both MMP-9 and TIMP-1. The present data suggest that high levels of MMP-9 protein in invasive epithelial ovarian carcinoma are strongly associated with tumor cell invasion. Enhanced expression of TIMP-1 protein in borderline and invasive tumors indicates that endogenous TIMP-1 protein may play a paradoxical role in ovarian tumor progression.

Diabetes and pancreatic tumours in transgenic mice expressing Pa x 6

AIMS/HYPOTHESIS

Both endocrine and exocrine cells of the pancreas differentiate from epithelial cells of primitive pancreatic ducts, and four types of pancreatic islet cells (alpha, beta, delta, and PP cells) are derived from the common pluripotent precursor cells. Although Pa x 6 is expressed in all islet cells, Pa x 4 is detected only in beta cells. In homozygous Pa x 4-null mice, beta cells are absent, whereas the number of alpha cells is increased. Therefore, we hypothesized that the balance of Pa x 4 and 6 is one of the determinants by which the common progenitor cells differentiate into alpha or beta cells.

METHODS

To change this balance, we generated transgenic mice overexpressing Pa x 6 driven by the insulin promoter or the PDX1 promoter.

RESULTS

In both types of transgenic mice, normal development of beta cells was disturbed, resulting in apoptosis of beta cells and diabetes. In Insulin/Pa x 6-Tg mice, beta cells were specifically affected, whereas in PDX/Pa x 6-Tg mice, developmental abnormalities involved the whole pancreas including hypoplasia of the exocrine pancreas. Furthermore, PDX/Pa x 6-Tg mice experienced proliferation of both ductal epithelia and islet cells and subsequent cystic adenoma of the pancreas.

CONCLUSION/INTERPRETATION

These findings suggest that Pa x 6 promotes the growth of ductal epithelia and endocrine progenitor cells and that the suppression of Pa x 6 is necessary for the normal development of beta cells and the exocrine pancreas.

Differential telomerase activity, expression of the telomerase catalytic sub-unit and telomerase-RNA in ovarian tumors

Telomerase activity has been found in a variety of malignant tumors but only rarely in benign tumors or normal tissues. In this study, we investigated telomerase activation in 37 ovarian tumors, including benign, borderline and malignant neoplasms. Telomerase activity was detected using the telomeric repeat amplification protocol (TRAP) in 13/16 ovarian carcinomas, 9/10 borderline tumors and 3/11 cystadenomas/fibromas. mRNA expression of the putative human telomerase catalytic sub-unit gene (hTERT) was detected by RT-PCR in 14/15 ovarian carcinomas, 8/10 borderline tumors and 4/11 cystadenomas/fibromas. In situ hybridization was performed to evaluate telomerase-RNA (hTR) expression in the corresponding paraffin-embedded tumors. Variable expression levels of hTR were found over neoplastic tumor cells. The highest levels of hTR expression were found predominantly in ovarian carcinomas. Although the amount of telomerase activity varied, significantly high levels of telomerase activity were found predominantly in ovarian carcinomas. hTERT mRNA expression was closely associated with telomerase activity. These findings suggest that up-regulation of hTERT and hTR is important for telomerase activation during malignant-tumor progression. Telomerase activation might therefore be a valuable diagnostic parameter that could help to identify potentially progressive lesions. However, the diagnostic and therapeutic implications of telomerase activation need to be clarified in clinical trials. Int. J. Cancer (Pred. Oncol.) 84:426-431, 1999.

Ki-ras codon 12 point mutation and p53 mutation in pancreatic diseases

BACKGROUND/AIMS

The Ki-ras gene located at 12p, encodes the GTP binding protein involving the signal transduction system and concerns cell proliferation and differentiation.

METHODOLOGY

Pancreatic tissues were obtained from 37 patients with various pancreatic diseases. Ki-ras codon 12 point mutation and p53 (exon 5-8) mutation were examined in 3 patients with chronic pancreatitis, 9 mucinous adenoma of the pancreas (2 with mucinous cystadenoma and 7 with intraductal papillary-mucinous adenoma), 22 pancreatic ductal carcinoma, and 3 serous cystadenoma.

RESULTS

On usual pancreatic exocrine ductal lesions, Ki-ras point mutation was evident in 0% (0/3) of chronic pancreatitis, in 56% (5/9) of mucinous adenoma, and in 57% (12/21) of ductal carcinoma, the mutation being located in the second letter in 18 and in the 1st letter in 2. One Ki-ras codon 12 positive pancreatic cancer showed Ki-ras codon 12 point mutation in the surrounding pancreas (2nd letter mutation in both areas). p53 mutation was present in 0% (0/1) of chronic pancreatitis, in 0% (0/8) of mucinous adenoma, while it was evident in 29% (6/21) of pancreatic ductal carcinoma, the mutation being situated in exon 5 in 3, in exon 6 in 1, and in exon 7 in 2. In 3 patients with serous cystadenoma, there was no mutation in Ki-ras codon 12 or p53 (exon 5-8).

CONCLUSIONS

These findings suggest that Ki-ras point mutation is involved in the early events of pancreatic ductal carcinoma, while p53 mutation is intricated in the late phase of pancreatic ductal carcinogenesis and the histogenesis of serous cystadenoma is different from that of pancreatic exocrine ductal lesions including mucinous adenoma and ductal carcinoma.

Expression of the imprinted H19 oncofetal RNA in epithelial ovarian cancer

STUDY

To examine the expression of the imprinted maternally expressed H19 gene in benign, low malignant potential (borderline) and malignant surface epithelial ovarian tumors.

DESIGN

In situ hybridization for H19 RNA using S-labeled and digoxigenin-labeled probes was performed on paraffin sections of ovarian surface epithelial tumors. The serous tumors included nine section cystadenomas, twelve serous tumors of low malignant potential and twenty serous carcinomas, grade I-IIII (FIGO classification). A smaller group included two mucinous cystadenomas, four mucinous tumors of low malignant potential and two mucinous cystadenocarcinomas.

RESULTS

H19 expression was found to be positive in 6/9 (67%) serous cystadenomas, 9/12 (75%) of serous tumors of low malignant potential and 13/20 (65%) of invasive serous carcinomas. Expression in mucinous tumors was confined to the stroma beneath the epithelial lining.

CONCLUSION

H19 is expressed in the majority of serous epithelial tumors. Taking into consideration the high percentage of H19 expressing serous ovarian neoplasms we suggest that H19 RNA may be used as an adjuvant tumor marker for the diagnosis and mainly for staging and follow-up of patients with serous ovarian carcinoma.

Ras gene activation in malignant cells of human ovarian carcinoma peritoneal fluids

In this study, we showed, for the first time, the pattern of point mutations at codon 12 of the K-ras, H-ras and N-ras genes, using polymerase chain reaction and restriction fragment length polymorphism analysis in 47 malignant cytologic specimens of ovarian adenocarcinoma peritoneal fluids. Forty-seven % of the samples were found to carry a point mutation at codon 12 of K-ras gene. Also, 21 cystadenoma peritoneal fluids were used as control specimens for the detection of ras mutations. Fourteen % of these samples were found to carry a point mutation at codon 12 of the K-ras gene. The prevalence of K-ras gene mutations were statistically correlated with FIGO and surgical stage of the malignant specimens. Our data demonstrates that the K-ras gene mutations are mainly affected (47%) in the malignant cells of the peritoneal washings or ascites of women with ovarian adenocarcinomas and may have value for the early diagnosis and monitoring of these neoplasms.

Are pancreatic tumors hormone dependent?: A case report of unusual, rapidly growing pancreatic tumor during pregnancy, its possible relationship to female sex hormones, and review of the literature

The occurrence of a pancreatic tumor in a young patient is rare. However, when one identifies a pancreatic mass during pregnancy and particularly when the lesion is located in the tail of the pancreas, "unusual tumors" of the pancreas should be considered. The management of these tumors during pregnancy presents unusual challenges because of rapid tumor growth probably related to elevated levels of sex hormones. An immunohistochemical study was done to evaluate for hormone receptors of the tissue removed from the tumor. We present a case of a 37-year-old female patient in her 4th week of pregnancy who was found to have a pancreatic mass; she was followed with ultrasonography. At the 23rd week of gestation, the tumor increased in size to more than 12 cm and required resection. Immunohistochemical studies were done to evaluate receptors for progesterone, estrogen, PS2-estrogen-related protein, pancreatic polypeptide antigen, flow cytometry, DNA ploidy, and proliferative activity in tumor cells. Pathology showed a low-grade multiloculated mucinous cystic neoplasm of the pancreas. There was a positivity for progesterone receptor and PS2-estrogen-related protein but not for estrogen receptor in the tumor. We conclude that a pancreatic mass detected during pregnancy requires a different consideration for its management. Early tissue diagnosis with CT or ultrasound-guided biopsy is essential. Even those lesions diagnosed as benign would require early intervention because of their rapid growth, probably influenced by female sex hormones.

In serous ovarian neoplasms the frequency of Ki-ras mutations correlates with their malignant potential

We analysed 44 tissue samples from serous ovarian neoplasms of different malignant potential for Ki-ras mutations by denaturing gradient gel electrophoresis (DGGE) and direct sequencing after microdissection. Point mutations at codon 12 were found in 7 of 20 tumours of low malignant potential (LMP) (35%) and in 2 of 6 well-differentiated carcinomas (33%). In contrast, no mutations were detected in the 11 poorly differentiated ovarian carcinoma samples or in the 7 serous cystadenomas. The frequency of Ki-ras mutations in serous ovarian tumours seems to correlate with the malignant potential of the neoplasms. The data favour the hypothesis of a de novo development of poorly differentiated ovarian carcinomas and do not support an evolution from LMP tumours or well-differentiated carcinomas.

Differences in p16 gene methylation and expression in benign and malignant ovarian tumors

OBJECTIVE

The aim of this study was to test the hypothesis that DNA methylation is important for silencing the p16 tumor suppressor gene in ovarian epithelial tumors and to compare the prevalence of this mechanism among different ovarian epithelial tumor subtypes.

METHOD

Methylation-specific PCR was used to analyze the p16 gene for DNA methylation in 20 ovarian cystadenomas, 15 low malignant potential (LMP) tumors, and 37 carcinomas. p16 expression was determined immunohistochemically in 58 of these tumors (16 cystadenomas, 13 LMP tumors, 29 carcinomas). Differences in methylation or expression rates between specific tumor subgroups were examined by Fisher's exact test.

RESULTS

Fragments from the distal promoter and beginning of the first exon of the p16 gene were both methylated in 5 of 15 (33%) LMP tumors compared to 2 of 37 (5%) carcinomas (P = 0. 02). Those sites were also methylated in 5 of 20 (25%) cystadenomas. Lack of p16 expression was present in 7 of 16 cystadenomas, 4 of 13 LMP tumors, and 22 of 29 carcinomas (P [LMPs versus carcinomas] = 0. 01) and correlated with methylation changes in LMP tumors (P = 0.05). p16 expression was correlated with mucinous differentiation in cystadenomas (P = 0.001).

CONCLUSION

p16 silencing may be important for the development of ovarian carcinomas and a subset of LMP tumors. Changes in DNA methylation may be more important for inactivation of this gene (and perhaps other tumor suppressor genes) in LMP tumors, which lack many of the alternative mechanisms present in carcinomas. p16 expression is primarily related to mucinous differentiation in cystadenomas.

Multifocal neoplasia involving the colon and appendix in ulcerative colitis: pathological and molecular features

A patient with ulcerative colitis, extensive dysplasia, multifocal colon cancer, and an appendiceal cystadenoma is described. A 48-year-old man with a 26-year history of ulcerative colitis (UC) had extensive dysplasia involving nearly the entire colon and four dysplasia-associated mass lesions (DALMs). Four invasive adenocarcinomas were present. This case is the first documentation of a DALM (mucinous cystadenoma) arising in the appendix in the setting of UC. The genetic alterations present in the various lesions were analyzed. The molecular profiles of the neoplastic lesions differed. Mutations were found in p53 and ras genes, and one site showed microsatellite instability in a single genetic locus. These molecular abnormalities develop before invasive cancer develops, and may undergo clonal expansion to create large mucosal patches containing certain cells with genetic alterations. The diversity of the early changes suggests that the recurrent inflammation characteristic of long-standing UC randomly damages genes known to participate in colon carcinogenesis and that it affects multiple target genes. The findings also support a multiclonal origin of synchronous tumors because the molecular phenotypes of the preinvasive lesions differed at various sites.

Loss of chromosome 18q is an early event in pancreatic ductal tumorigenesis

Cytogenetic and molecular studies demonstrated that pancreatic cancer frequently shows specific chromosomal abnormalities, such as losses of 9p, 17p, and 18q, and gains of 8q and 20q. We have analyzed alterations in the copy number of specific chromosomal regions in cells from the pancreatic juices of 32 patients with various pancreatic disorders by fluorescence in situ hybridization (FISH) technique to pursue the possible clinical use of early diagnosis of pancreatic cancer. None of the chromosomal abnormalities were found in 13 specimens from individuals who had no neoplastic lesions. On the other hand, 12 specimens (63%) derived from the remaining 19 patients who had neoplastic lesions showed at least one chromosomal abnormality. Ten of these specimens were from pancreatic cancer patients; 7 cases (70%) showed chromosomal abnormalities. All but one of the 12 tumors with chromosomal abnormalities had loss of 18q. Furthermore, we detected a tumor in one patient in whom the routine cytological method and endoscopic retrograde chorangiopancreatography found nothing. Based on the results by FISH, we performed endoscopic ultrasonography and found a small serous cystadenoma in this patient. These results indicate that: (a) FISH analysis of cells from pancreatic juices obtained during endoscopic retrograde chorangiopancreatography is quite useful for detecting pancreatic ductal tumors; and (b) loss of chromosome 18q is one of the early genetic changes that provide very useful information in diagnosing pancreatic neoplasias.

Retinoblastoma protein expression in ovarian epithelial neoplasms

Progress has been made in identifying the molecular changes that occur in ovarian carcinoma; still our understanding of these changes and their interactions remains incomplete. In the present study the authors examined the expression of retinoblastoma protein, a tumor suppressor protein, in a spectrum of ovarian epithelial tumors including cystadenomas, low-malignant-potential tumors, and carcinomas. A heterogeneous pattern of reactivity was observed in all of the cystadenomas, in all of the low-malignant-potential tumors, and in a majority (27/34) of the carcinomas. The remaining carcinomas showed either a complete absence of reactivity or a pattern of altered reactivity characterized by areas of tumor with intact reactivity adjacent to zones of tumor with a complete absence of reactivity. There was no significant association between grade or stage and absent/altered reactivity. We conclude that alterations of retinoblastoma protein expression are uncommon in ovarian carcinoma.

No evidence for microsatellite instability from allelotype analysis of benign and low malignant potential ovarian neoplasms

The genetic events that lead to the development of benign and low malignant potential (LMP) tumors from normal ovarian surface epithelium are not well understood. In contrast to invasive ovarian neoplasms, loss of heterozygosity (LOH) is not common in these tumors except on the X chromosome, but one report has suggested that an alternative genetic mechanism, microsatellite instability (MSI), might be an important pathogenic mechanism for LMP ovarian tumors.

OBJECTIVE

To determine the frequency of MSI in LMP tumors and to detect novel regions of LOH in benign and LMP ovarian tumors.

METHODS

Sixty-nine microsatellite markers were analyzed in 23 benign and 31 LMP ovarian tumors.

RESULTS

No evidence of MSI was found in any of the tumors studied, nor were any novel regions of LOH identified.

CONCLUSIONS

This suggests that new approaches may be necessary to understand the genetic basis of benign and LMP ovarian neoplasms since neither LOH nor MSI appears to play a major role.

Expression of cadherins and CD44 isoforms in ovarian endometrial cysts

We evaluated the immunohistochemical expression of cadherins and CD44 variants in 20 endometriomas, 20 cystadenomas, 20 borderline ovarian tumours as well as 20 ovarian carcinomas, and the serological and cystic fluid concentrations of soluble E-cadherin and soluble CD44 standard (sCD44sdt) in 20 endometriomas, 20 cystadenomas, six borderline and 11 carcinomas of the ovary. In endometriomas, immunostaining of E- and N-cadherin was negative (20 and 30% respectively). CD44 H, v3 and v6 immunostaining were detected in 63, 10 and 40% respectively. A difference in immunostaining for E-cadherin was found between endometriomas and cystadenomas (P < 0.001) and for N-cadherin between endometriomas and carcinomas (P < 0.001). A difference in CD44H immunostaining was observed between endometriomas and cystadenomas (P < 0.035) but not with borderline ovarian tumours and carcinomas. No difference in serum concentrations of soluble E-cadherins and CD44 standard was found between the four groups of tumours. Cystic fluid concentrations of E-cadherin were lower in endometriomas than in borderline tumours and ovarian carcinomas (P < 0.001). High concentrations of soluble CD44 standard cystic fluid were found in endometriomas than in other ovarian cysts. Endometriomas and borderline tumours share alterations of cadherins and CD44 isoforms which may help in the understanding of the aggressive and invasive potentials of endometriotic cells.

Frequent loss of chromosome 12 in human epithelial ovarian tumors: a chromosomal in situ hybridization study

The short arm isochromosome of chromosome 12 and trisomy 12 are well-established chromosomal alterations in human ovarian germ cell tumors. However, numerical aberrations of chromosome 12 in epithelial ovarian tumors (EOTs) are highly controversial; both trisomy 12 and monosomy 12 have been observed. We performed chromosomal in situ hybridization in paraffin-embedded and formalin-fixed tissue sections of 31 EOTs. Twenty-five EOTs could be evaluated statistically (2 mucinous, 11 serous, 5 endometrioid, 3 borderline, and 4 other epithelial-type tumors) to examine the copy number of chromosome 12 and 15. The frequency distribution of hybridization signals with alpha-satellite centromeric DNA probes for chromosome 15 revealed disomy in all cases. However, we found the loss of chromosome 12 in 16 of 25 tumor samples. No correlation was found between the presence of monosomy 12 and the clinical stage of the tumors. Frequent loss of chromosome 12 may indicate that this chromosome is involved in the tumorigenesis of EOTs. Further studies are needed to clarify whether loss of chromosome 12 is an early or late event in ovarian carcinogenesis.

Heterogeneous distribution of K-ras-mutated epithelia in mucinous ovarian tumors with special reference to histopathology

The carcinogenic process of epithelial ovarian carcinomas is still unknown, and both pathways of de novo carcinogenesis from the surface epithelium and malignant transformation of benign cystadenoma have been suggested. Especially in mucinous ovarian tumors, the transition from benign cystadenomas to tumors of low malignant potential (LMP) or carcinomas has been implicated. To elucidate this possibility, we analyzed the presence or absence of heterogeneity of the K-ras mutation corresponding to the histological heterogeneity in 71 epithelial ovarian tumors, including 31 mucinous tumors. K-ras mutation was identified in nine mucinous tumors (4 of 10 carcinomas, 4 of 14 LMP tumors, and 1 of 7 cystadenomas) and in two nonmucinous carcinomas. Microdissection of multiple sites with reference to their histological appearance showed the heterogeneous distribution of K-ras-mutated epithelia in two of the nine mucinous tumors. One mucinous carcinoma showed K-ras mutation in all of the histologically LMP and malignant portions, but not in benign portions. In another LMP tumor, all of the LMP portions and one of the benign portions showed K-ras mutation, whereas the other two benign portions had no mutation. In the remaining seven mucinous tumors with K-ras mutation, however, there was a homogeneous distribution of K-ras-mutated epithelia irrespective of their histological appearance. These findings suggest that the K-ras mutation occurs during the transformation from benign cystadenomas to LMP or malignant lesions, providing molecular genetic support for the hypothesis of the "adenoma-carcinoma sequence" in some mucinous ovarian tumors, but in other cases an alternative pathway may also be possible.

Frequent loss of p16 expression and its correlation with clinicopathological parameters in pancreatic carcinoma

Expression of the p16 gene product in human primary pancreatic carcinoma (PC) was investigated in paraffin-embedded tissue using a monoclonal antibody against p16 protein, clone G175-405, by means of immunohistochemistry, and the correlation of results with various clinicopathological parameters was evaluated. All six cases of normal pancreas and all but 1 of 20 cases of chronic pancreatitis expressed p16 protein, whereas 37.5% (3 of 8) of cystadenomas and 41. 9% (26 of 62) of PCs lost p16 expression. There was a significant difference between chronic pancreatitis and PC for frequency of the loss of p16 expression (P < 0.01). Moreover, loss of p16 expression in pancreatic malignancy was significantly associated with histological grade (G1 versus G2 and G3, P < 0.01) but not with sex, age, clinical stage, tumor location, or resectability. The survival period was shorter and metastasis is more likely in those cases that did not show p16 expression than those that did.

Epididymal cystadenomas in von Hippel-Lindau disease

OBJECTIVES

Epididymal cystadenomas (ECs) are frequently found in association with von Hippel-Lindau disease (VHL), but little has been reported about their sonographic appearance. We review the sonographic appearance of ECs, the relationship of ECs to other manifestations of VHL, and the specific genetic mutations associated with ECs.

METHODS

Fifty-six male patients with VHL were examined with scrotal sonography and physical examination as part of a larger screening program for VHL. The head of the epididymis was measured in two planes on sonography and compared with age-matched normal controls. All VHL patients with palpable epididymal abnormalities or enlargement (more than two standard deviations) of the head of the epididymis on ultrasound were considered positive for EC.

RESULTS

Thirty of 56 (54%) male patients with VHL demonstrated a unilateral (n = 10; 33%) or bilateral (n = 20; 67%) solid abnormality in the head of the epididymis suggestive of EC. Sonographic appearances ranged from a solid mass with multiple tiny cysts to an almost completely solid mass. The most common appearance was a 15- to 20-mm solid mass with small cystic components. Dilated efferent ductules were seen within the testicle in 7 men, evidently a result of chronic obstruction. There was no association between the clinical subtype of VHL and the presence of ECs (P > 0.10, chi square). Mutations resulting in a truncated gene product were associated with the development of ECs but the association did not reach statistical significance (P = 0.06).

CONCLUSIONS

ECs are a common manifestation of VHL in men and exhibit a range of appearances on ultrasound. Sonography can be used to identify ECs and determine the extent of cystic dilation of the rete testes. The benign course of ECs and the usual absence of clinical symptoms favor a conservative approach to their management.

Overexpression of cyclin D1 in epithelial ovarian cancers

Amplification and overexpression of the cell cycle-related gene cyclin D1 have been demonstrated in several human malignancies and have been shown to be directly oncogenic in breast epithelium and lymphocytes. Overexpression of the gene can occur in the absence of gene amplification. We have investigated whether cyclin D1 is overexpressed in a panel of 43 sporadic epithelial ovarian cancers using immunohistochemistry. Cyclin D1 was overexpressed in 26% of these tumors. Overexpression of cyclin D1 is associated with borderline or well-differentiated, grade 1 tumors but does not correlate with a particular histological type, overexpression of the c-erb-B2 oncogene, or presence of estrogen receptors. It is suggested that overexpression of cyclin D1 may contribute to the pathogenesis of epithelial ovarian cancers, including a subset of tumors different from those overexpressing the c-erb-B2 oncogene.

Alterations in DNA methylation are early, but not initial, events in ovarian tumorigenesis

We compared global levels of DNA methylation as well as methylation of a specific locus (MyoD1) in ovarian cystadenomas, ovarian tumours of low malignant potential (LMP) and ovarian carcinomas to investigate the association between changes in DNA methylation and ovarian tumour development. As we realized that cystadenomas showed different methylation patterns from both LMP tumours and carcinomas, we verified their monoclonal origin as a means of confirming their true neoplastic nature. High-pressure liquid chromatographic (HPLC) analyses showed that global methylation levels in LMP tumours and carcinomas were 21% and 25% lower than in cystadenomas respectively (P = 0.0001 by one-way variance analysis). Changes in the methylation status of the MyoD1 locus were not seen in any of ten cystadenomas analysed but were present in five of ten LMP tumours and in five of ten carcinomas (P = 0.03). These findings suggest that alterations in DNA methylation are absent (or at least not as extensive) in ovarian cystadenomas, but are present in LMP tumours, the phenotypic features of which are intermediate between those of benign and malignant ovarian tumours. The results also emphasize the merit of distinguishing ovarian LMP tumours from cystadenomas, in spite of their similar clinical characteristics.

p53 protein expression and DNA ploidy in cystic tumors of the pancreas

Cystic tumors of the pancreas form a heterogeneous group, with benign, premalignant, and malignant tumors. The molecular events that underlie their neoplastic transformation process are poorly understood. Our purpose was to study DNA ploidy by flow cytometry and p53 protein expression by immunohistochemistry in a large series of cystic tumors of the pancreas. The series of 51 surgical specimens included 18 serous cystadenomas, 20 mucinous cystic tumors (benign, n = 14; borderline, n = 1; malignant, n = 5), 10 intraductal papillary-mucinous tumors (benign, n = 4; borderline, n = 1; malignant, n = 5), and 3 papillary and cystic tumors. The p53 protein immunohistochemical study was done in all cases on deparaffinized sections stained with the monoclonal antibody DO7. DNA flow cytometry was performed in 31 cases on formalin-fixed and paraffinembedded material. Neither p53 protein immunoreactivity nor DNA aneuploidy was observed in any case of serous cystadenoma. p53 protein overexpression was present in four of five malignant mucinous cystic tumors but was absent in benign and borderline cases. Only one case of malignant mucinous cystic tumor was DNA aneuploid. All benign and borderline intraductal papillary-mucinous tumors were p53 negative, and two of five malignant cases were p53 positive. There was no DNA aneuploidy in any case of intraductal papillary-mucinous tumors. The three cases of papillary-cystic tumors showed neither p53 protein immunoreactivity nor DNA aneuploidy. In cystic tumors of the pancreas, p53 protein overexpression and DNA aneuploidy are rare events, restricted to malignant cases, mostly mucinous cystadenocarcinomas. Our results confirm that this group of tumors is heterogeneous and underline the need for earlier markers of an aggressive behavior.

Pulmonary malformation in transgenic mice expressing human keratinocyte growth factor in the lung

Expression of human keratinocyte growth factor (KGF/FGF-7) was directed to epithelial cells of the developing embryonic lung of transgenic mice disrupting normal pulmonary morphogenesis during the pseudoglandular stage of development. By embryonic day 15.5(E15.5), lungs of transgenic surfactant protein C (SP-C)-KGF mice resembled those of humans with pulmonary cystadenoma. Lungs were cystic, filling the thoracic cavity, and were composed of numerous dilated saccules lined with glycogen-containing columnar epithelial cells. The normal distribution of SP-C proprotein in the distal regions of respiratory tubules was disrupted. Columnar epithelial cells lining the papillary structures stained variably and weakly for this distal respiratory cell marker. Mesenchymal components were preserved in the transgenic mouse lungs, yet the architectural relationship of the epithelium to the mesenchyme was altered. SP-C-KGF transgenic mice failed to survive gestation to term, dying before E17.5. Culturing mouse fetal lung explants in the presence of recombinant human KGF also disrupted branching morphogenesis and resulted in similar cystic malformation of the lung. Thus, it appears that precise temporal and spatial expression of KGF is likely to play a crucial role in the control of branching morphogenesis during fetal lung development.