Differential gene expression in ovarian carcinoma: identification of potential biomarkers

Ovarian cancer remains the fifth leading cause of cancer death for women in the United States. In this study, the gene expression of 20 ovarian carcinomas, 17 ovarian carcinomas metastatic to the omentum, and 50 normal ovaries was determined by Gene Logic Inc. using Affymetrix GeneChip HU_95 arrays containing approximately 12,000 known genes. Differences in gene expression were quantified as fold changes in gene expression in ovarian carcinomas compared to normal ovaries and ovarian carcinoma metastases. Genes up-regulated in ovarian carcinoma tissue samples compared to more than 300 other normal and diseased tissue samples were identified. Seven genes were selected for further screening by immunohistochemistry to determine the presence and localization of the proteins. These seven genes were: the beta8 integrin subunit, bone morphogenetic protein-7, claudin-4, collagen type IX alpha2, cellular retinoic acid binding protein-1, forkhead box J1, and S100 calcium-binding protein A1. Statistical analyses showed that the beta8 integrin subunit, claudin-4, and S100A1 provided the best distinction between ovarian carcinoma and normal ovary tissues, and may serve as the best candidate tumor markers among the seven genes studied. These results suggest that further exploration into other up-regulated genes may identify novel diagnostic, therapeutic, and/or prognostic biomarkers in ovarian carcinoma.     

Serous papillary adenocarcinoma of the female genital organs and invasive micropapillary carcinoma of the breast. Are WT1, CA125, and GCDFP-15 useful in differential diagnosis?

Serous papillary adenocarcinoma of the female genital organs and invasive micropapillary carcinoma of the breast have close histologic similarities. Thus, when these cancers occur synchronously or metachronously in the same patient, it is difficult to determine the primary site. We examined 23 serous papillary adenocarcinomas (16 ovarian, 5 endometrial, and 2 peritoneal) and 37 invasive micropapillary carcinomas of the breast (12 pure and 25 mixed types) on immunohistochemical expression of Wilm's tumor antigen-1 (WT1), CA125, and gross cystic disease fluid protein-15 (GCDFP-15), which have been reported to be useful in the differential diagnosis of primary ovarian carcinomas versus metastatic breast cancer to the ovary. The positive rates of WT1, CA125, and GCDFP-15 in serous papillary adenocarcinomas were 78%, 78%, and 0%, respectively, and the corresponding rates in invasive micropapillary carcinomas were 3%, 40%, and 38%. The CA125-positive rate of invasive micropapillary carcinoma was higher than the rate reported for other types of breast carcinomas. We consider CA125 to be not always useful in the differential diagnosis of serous papillary adenocarcinoma and invasive micropapillary carcinoma. Although the positive rate of WT1 was significantly higher in serous papillary adenocarcinoma than in invasive micropapillary carcinoma, WT1 expression in endometrial serous papillary adenocarcinoma was infrequent (20%). WT1 and GCDFP-15 could be useful markers for the differential diagnosis of ovarian and peritoneal serous papillary adenocarcinoma versus breast invasive micropapillary adenocarcinoma. However, the availability of GCDFP-15 is limited because of the low positive rate of GCDFP-15 in invasive micropapillary carcinomas.     

The expression of Wilms' tumour-1 and Ca125 in invasive micropapillary carcinoma of the breast

AIM: Metastases from ovarian serous papillary carcinoma to the breast and primary invasive micropapillary carcinoma of the breast are histologically similar. The distinction is clinically important to ensure appropriate management. Wilms' tumour-1 (WT1) and Ca125 are frequently expressed in serous papillary carcinomas, and uncommonly in unselected mammary carcinomas. One previous study found Ca125 expression in 69% of invasive micropapillary carcinomas. The aim was to assess the frequency of expression of WT1 and Ca125 in invasive micropapillary carcinoma. METHODS AND RESULTS: Twenty-five of 34 invasive micropapillary carcinomas showed no nuclear expression of WT1. The remaining nine tumours showed weak to moderate immunoreactivity in 1-10% of nuclei. Six of these nine tumours also contained ductal carcinoma in situ, which expressed WT1 in five of the six. Membranous or cytoplasmic expression of Ca125 was found in seven tumours. CONCLUSION: Nuclear WT1 expression is present in a minority of invasive micropapillary carcinomas and, when present, expression is focal. The frequency of expression of Ca125 was similar to the results in unselected mammary carcinoma. Thus, these markers are useful members of the immunohistochemical panel for the distinction of mammary invasive micropapillary carcinoma from ovarian serous papillary carcinoma.     

Expression of Rsf-1, a chromatin-remodeling gene, in ovarian and breast carcinoma

Rsf-1 protein is a member of a chromatin-remodeling complex that plays an important role in regulating gene expression and cell proliferation. Our previous study showed that Rsf-1 was an amplified gene that participated in the development of ovarian serous carcinoma. To further elucidate the role of Rsf-1 in ovarian cancer, we studied Rsf-1 immunoreactivity in 294 ovarian tumors of various histologic types. Because the Rsf-1 amplicon overlaps an amplified region reported in breast cancer, we included 782 neoplastic and normal breast tissues for comparison. Immunohistochemistry was performed on tissue microarrays using a 4-tiered scoring system. Overexpression of Rsf-1 was defined as a nuclear immunointensity of 3+ to 4+ because of a strong correlation between 3+ and 4+ immunointensity and Rsf-1 gene amplification, based on our previous fluorescence in situ hybridization analysis. Rsf-1 overexpression was observed in 25% of high-grade ovarian serous carcinomas and in only rare cases (<7%) of low-grade ovarian serous, ovarian endometrioid, and invasive breast carcinomas but not in any ovarian serous borderline tumors, ovarian clear cell carcinomas, ovarian mucinous carcinomas, intraductal carcinomas of the breast, and normal ovaries and breast tissues. Thus, overexpression of Rsf-1 was significantly associated with high-grade ovarian serous carcinoma (P < .05), as compared with other types of ovarian tumors and breast carcinomas. Our results provide evidence that Rsf-1 expression is primarily confined to high-grade serous carcinoma, the most aggressive ovarian cancer. Because Rsf-1 overexpression occurs in only a small number of breast carcinomas, it is unlikely that Rsf-1 is a critical gene in the development of breast carcinoma.     

WT1 immunoreactivity in uterine papillary serous carcinomas is different from ovarian serous carcinomas

WT1 diffusely stains most ovarian serous carcinomas; reactivity of uterine papillary serous carcinomas has not been evaluated. We studied WT1 expression in 13 International Federation of Gynecology and Obstetrics stage 1 and 5 stage 3 or 4 uterine papillary serous carcinomas without ovarian metastases and compared their reactivity with the WT1 staining of 30 ovarian serous carcinomas. WT1 reactivity was evaluated with the C19 and 6F-H2 antibody clones. All 18 uterine papillary serous carcinomas were nonreactive for WT1. The nonovarian metastases of the 5 high-stage uterine papillary serous carcinomas also were nonreactive for WT1. In contrast, 29 (97%) of 30 ovarian serous carcinomas were reactive for WT1. WT1 reactivity in an unknown primary serous carcinoma would suggest it is from a nonuterine site. The mechanisms underlying these findings are unknown. They raise the possibility of genetic differences between the 2 morphologically similar neoplasms.     

Value of mesothelial and epithelial antibodies in distinguishing diffuse peritoneal mesothelioma in females from serous papillary carcinoma of the ovary and peritoneum

AIMS: To evaluate the role of mesothelial markers (calretinin, thrombomodulin, cytokeratin 5/6, and CD44H) and carcinoma markers (polyclonal and monoclonal carcinoembryonic antigen, Leu-M1, CA-125 and Ber-EP4) in distinguishing diffuse peritoneal malignant mesothelioma from primary serous papillary adenocarcinoma of the ovary and peritoneum. METHODS AND RESULTS: Paraffin-embedded formalin-fixed blocks from 32 diffuse peritoneal mesotheliomas of epithelial subtype (all females), 20 serous papillary ovarian carcinomas and three primary peritoneal serous papillary carcinomas were studied. Calretinin and Ber-EP4 appeared to be the best positive mesothelial and carcinoma marker, respectively. Nuclear calretinin expression was identified in 28 of 32 malignant mesotheliomas with no nuclear immunoreactivity in the cohorts of serous papillary ovarian and peritoneal carcinomas, thus yielding 88% sensitivity and 100% specificity. Ber-EP4 showed 95% sensitivity and 91% specificity for serous papillary ovarian carcinoma. Thrombomodulin, cytokeratin 5/6 and CD44H immunoreactivities were seen in 18 (56%), 17 (53%) and 15 (47%) of peritoneal mesotheliomas, respectively, and in six (30%), five (25%) and five (25%) of the ovarian tumours, respectively. None of the three primary peritoneal serous papillary carcinomas expressed calretinin, thrombomodulin, cytokeratin 5/6 or CD44H. Polyclonal and monoclonal CEA, and Leu-M1 were expressed by two (10%), one (5%) and seven (35%) serous papillary ovarian carcinomas, respectively. None of the serous papillary peritoneal carcinomas expressed polyclonal CEA, monoclonal CEA or Leu-M1. CA-125 was positive in 19 (95%) and two (67%) ovarian and peritoneal carcinomas, respectively, and in eight (25%) peritoneal mesotheliomas. CONCLUSIONS: Calretinin and Ber-EP4 are useful discriminant markers in distinguishing peritoneal mesothelioma in women from serous papillary ovarian and peritoneal carcinoma. The other mesothelial markers (thrombomodulin, cytokeratin 5/6, and CD44H) and carcinoma markers (polyclonal and monoclonal CEA, and Leu-M1) yielded a too low sensitivity for practical use.     

Caveolin-1 Is Down-Regulated in Human Ovarian Carcinoma and Acts as a Candidate Tumor Suppressor Gene

To identify novel markers differentially expressed in ovarian cancer versus normal ovary, we hybridized microarrays with cDNAs derived from normal human ovaries and advanced stage ovarian carcinomas. This analysis revealed down-regulation of the caveolin-1 gene (CAV1) in ovarian carcinoma samples. Suppression of CAV1 in ovarian carcinomas was confirmed using a tumor tissue array consisting of 68 cDNA pools from different matched human tumor and normal tissues. Immunohistochemistry demonstrated expression of caveolin-1 in normal and benign ovarian epithelial cells, but loss of expression in serous ovarian carcinomas. In low-grade carcinomas, redistribution of caveolin-1 from a membrane-associated pattern observed in normal epithelium to a cytoplasmic localization pattern was observed. No expression of caveolin-1 was detectable in four of six ovarian carcinoma cell lines investigated. In SKOV-3 and ES-2 carcinoma cells, which express high levels of the caveolin-1 protein, phosphorylation of the 22-kd caveolin-1 isoform was detected. Inhibition of both DNA methylation and histone deacetylation using 5-aza-2'deoxycytidine and Trichostatin A, respectively, relieves down-regulation of caveolin-1 in OAW42 and OVCAR-3 cells which is in part mediated by direct regulation at the mRNA level. Expression of CAV1 in the ovarian carcinoma cell line OVCAR-3, resulted in suppression of tumor cell survival in vitro, suggesting that the CAV1 gene is likely to act as a tumor suppressor gene in human ovarian epithelium.     

Allelic Analysis of Serous Ovarian Carcinoma Reveals Two Putative Tumor Suppressor Loci at 18q22-q23 Distal to SMAD4, SMAD2, and DCC

The distal half of chromosome arm 18q is frequently lost in ovarian carcinoma. To define the putative tumor suppressor locus/loci more precisely we performed allelic analysis with 27 polymorphic microsatellite markers located at 18q12.3-q23 in 64 serous and 9 mucinous ovarian carcinomas. Fifty-nine percent of the serous carcinomas, but only one (11%) of mucinous carcinomas, showed allelic loss at one or more loci (P = 0.018). In serous carcinomas, deletions were found to be associated with tumor grade and poor survival. The highest frequency of losses was detected at the distal part, 18q22-q23. Two minimal common regions of loss (MCRL) were identified at this region: MCRL1 between D18S465 and D18S61 at 18q22 (3.9 cM) and MCRL2 between D18S462 and D18S70 at 18q23 (5.8 cM). At 18q21.1, proximal to the MCRLs, there are three candidate tumor suppressor genes: SMAD4 (DPC4), SMAD2, and DCC. Their protein expression was studied by immunohistochemistry in normal ovarian tissue and serous carcinomas. Lost or very weak expression of SMAD4, SMAD2 and DCC was found in 28, 28, and 30% of serous carcinomas, respectively. Comparison of allelic loss and protein expression status indicated that none of these genes alone could be the target for the frequent allelic loss at 18q21.1. Together, these genes may account for a substantial proportion of the events, but not all of them. Thus, we propose that the frequent allelic loss at 18q is because of the effect of multiple genes, and there is at least one as yet unidentified tumor suppressor gene at 18q residing distal to SMAD4, SMAD2, and DCC involved in serous ovarian carcinoma.     

Low-grade serous carcinomas of the ovary contain very few point mutations

It has been well established that ovarian low-grade and high-grade serous carcinomas are fundamentally different types of tumours. While the molecular genetic features of ovarian high-grade serous carcinomas are now well known, the pathogenesis of low-grade serous carcinomas, apart from the recognition of frequent somatic mutations involving KRAS and BRAF, is largely unknown. In order to comprehensively analyse somatic mutations in low-grade serous carcinomas, we applied exome sequencing to the DNA of eight samples of affinity-purified, low-grade, serous carcinomas. A remarkably small number of mutations were identified in seven of these tumours: a total of 70 somatic mutations in 64 genes. The eighth case displayed mixed serous and endometrioid features and a mutator phenotype with 783 somatic mutations, including a nonsense mutation in the mismatch repair gene, MSH2. We validated representative mutations in an additional nine low-grade serous carcinomas and 10 serous borderline tumours, the precursors of ovarian low-grade, serous carcinomas. Overall, the genes showing the most frequent mutations were BRAF and KRAS, occurring in 10 (38%) and 5 (19%) of 27 low-grade tumours, respectively. Except for a single case with a PIK3CA mutation, other mutations identified in the discovery set were not detected in the validation set of specimens. Our mutational analysis demonstrates that point mutations are much less common in low-grade serous tumours of the ovary than in other adult tumours, a finding with interesting scientific and clinical implications.     

Gene discovery in bladder cancer progression using cDNA microarrays

To identify gene expression changes along progression of bladder cancer, we compared the expression profiles of early-stage and advanced bladder tumors using cDNA microarrays containing 17,842 known genes and expressed sequence tags. The application of bootstrapping techniques to hierarchical clustering segregated early-stage and invasive transitional carcinomas into two main clusters. Multidimensional analysis confirmed these clusters and more importantly, it separated carcinoma in situ from papillary superficial lesions and subgroups within early-stage and invasive tumors displaying different overall survival. Additionally, it recognized early-stage tumors showing gene profiles similar to invasive disease. Different techniques including standard t-test, single-gene logistic regression, and support vector machine algorithms were applied to identify relevant genes involved in bladder cancer progression. Cytokeratin 20, neuropilin-2, p21, and p33ING1 were selected among the top ranked molecular targets differentially expressed and validated by immunohistochemistry using tissue microarrays (n = 173). Their expression patterns were significantly associated with pathological stage, tumor grade, and altered retinoblastoma (RB) expression. Moreover, p33ING1 expression levels were significantly associated with overall survival. Analysis of the annotation of the most significant genes revealed the relevance of critical genes and pathways during bladder cancer progression, including the overexpression of oncogenic genes such as DEK in superficial tumors or immune response genes such as Cd86 antigen in invasive disease. Gene profiling successfully classified bladder tumors based on their progression and clinical outcome. The present study has identified molecular biomarkers of potential clinical significance and critical molecular targets associated with bladder cancer progression.     

Identification of heterogeneity among soft tissue sarcomas by gene expression profiles from different tumors

The heterogeneity that soft tissue sarcomas (STS) exhibit in their clinical behavior, even within histological subtypes, complicates patient care. Histological appearance is determined by gene expression. Morphologic features are generally good predictors of biologic behavior, however, metastatic propensity, tumor growth, and response to chemotherapy may be determined by gene expression patterns that do not correlate well with morphology. One approach to identify heterogeneity is to search for genetic markers that correlate with differences in tumor behavior. Alternatively, subsets may be identified based on gene expression patterns alone, independent of knowledge of clinical outcome. We have reported gene expression patterns that distinguish two subgroups of clear cell renal carcinoma (ccRCC), and other gene expression patterns that distinguish heterogeneity of serous ovarian carcinoma (OVCA) and aggressive fibromatosis (AF). In this study, gene expression in 53 samples of STS and AF [including 16 malignant fibrous histiocytoma (MFH), 9 leiomyosarcoma, 12 liposarcoma, 4 synovial sarcoma, and 12 samples of AF] was determined at Gene Logic Inc. (Gaithersburg, MD) using Affymetrix GeneChip^® U_133 arrays containing approximately 40,000 genes/ESTs. Gene expression analysis was performed with the Gene Logic Genesis Enterprise System^® Software and Expressionist software. Hierarchical clustering of the STS using our three previously reported gene sets, each generated subgroups within the STS that for some subtypes correlated with histology, and also suggested the existence of subsets of MFH. All three gene sets also recognized the same two subsets of the fibromatosis samples that we had found in our earlier study of AF. These results suggest that these subgroups may have biological significance, and that these gene sets may be useful for sub-classification of STS. In addition, several genes that are targets of some anti-tumor drugs were found to be differentially expressed in particular subsets of STS.     

EphB3 protein is associated with histological grade and FIGO stage in ovarian serous carcinomas

Eph (Erythropoietin‐producing human hepatocellular carcinoma cell) is the largest subfamily of receptor tyrosine kinases. Eph receptors and their ephrin ligands are involved in embryonic development and physiological processes. Aberrant expression of Eph/ephrin may contribute to a variety of diseases including cancer. EphB3 is a member of Eph receptors and has been found to play roles in carcinogenesis of some types of human cancer. But, its expression and clinical significance in ovarian serous carcinoma have not been well investigated and are unknown. In this study, a set of ovarian tissues including normal fallopian tube, serous borderline tumor, and serous carcinoma were subjected to immunohistochemistry using a specific polyclonal antibody for EphB3. The relationship between EphB3 expression and clinicopathological parameters was statistically analyzed. EphB3 was strongly expressed in all fallopian tube specimens (19/19, 100%). EphB3 was negatively or weekly expressed in 1 of 17 (5.8%) in borderline tumors and 26 of 50 (52.0%) in serous carcinomas, moderately expressed in 7 of 17 (41.2%) in borderline tumors and 14 of 50 (28%) in serous carcinomas, and strongly expressed in 9 17 (52.9%) in borderline tumors and 10 of 50 (20%) in serous carcinomas. EphB3 expression is significantly reduced in serous carcinomas compared with normal fallopian tubes and borderline tumors (p < 0.001). EphB3 expression is negatively associated with histological grade (p < 0.001, r_s = ?0.613) and FIGO stage (p = 0.001, r_s = ?0.464) of serous carcinomas. Our results show EphB3 protein lost in ovarian serous carcinoma and is associated with tumor grade and FIGO stage, which indicate EphB3 protein may play a role in carcinogenesis of ovarian serous carcinoma and may be used as a molecular marker for prognosis.     

CA125 and thyroglobulin staining in papillary carcinomas of thyroid and ovarian origin is not completely specific for site of origin

AIMS: A 70-year-old woman presented with metastatic psammoma body-rich papillary carcinoma in a supraclavicular lymph node. No primary site was evident. The tumour showed strong staining for CA125 and weak staining for thyroglobulin. Prompted by this case we aimed to assess the reliability of immunostaining for CA125 and thyroglobulin in making the distinction between thyroid and ovarian papillary carcinoma. METHODS AND RESULTS: Nine papillary carcinomas of the thyroid and 17 serous papillary carcinomas of the ovary were stained for CA125 and thyroglobulin, as well as CAM 5.2, LP 34, carcinoembryonic antigen (CEA), S100 and diastase/periodic acid-Schiff. Nine of nine thyroid carcinomas stained for thyroglobulin; in addition CA125 was positive in four of nine. Normal surrounding thyroid also showed some reaction. Seventeen of 17 ovarian serous carcinomas were positive for CA125; in addition one case showed moderately strong staining for thyroglobulin. Mucin stains were positive in 14/17 ovarian serous carcinomas, but negative in all thyroid carcinomas. The other antibodies assessed showed no useful differences in staining frequency. Conclusion: Many cases of papillary carcinoma of the thyroid show CA125 staining, and this feature therefore has little positive predictive value for an ovarian origin. Occasional cases of ovarian papillary carcinoma may show staining for thyroglobulin, and this result should therefore be interpreted cautiously.     

Insulin-like growth factor-binding protein 2 and 5 are differentially regulated in ovarian cancer of different histologic types.

The family of insulin-like growth factor-binding proteins (IGFBPs) comprises six members, which bind and regulate the functions of insulin-like growth factors. Overexpression of IGFBP2 and IGFBP5 contributes to the invasiveness and progression of several human cancers, but their role and clinical significance in ovarian cancer has not been investigated in detail. We examined IGFBP2 and IGFBP5 expression levels using two tissue microarrays, one containing six normal surface epithelium, six benign serous cysts, 10 serous borderline tumors, eight low-grade, and 20 high-grade serous carcinomas. The other comprising 441 ovarian cancers of different histologic types linked to a clinicopathologic database. Each tumor was sampled in duplicate with a 1.0-mm punch core needle. Immunohistochemical staining was performed using antibodies against IGFBP2 or IGFBP5. The staining intensity was scored semiquantitatively as negative (0), weak (1-10%), moderate (10-50%), or strong (50-100%) using computerized image analysis. Statistical analyses used Fisher's exact test and Kaplan-Meier method. IGFBP2 and IGFBP5 were overexpressed in high-grade serous carcinomas compared to normal surface epithelium, benign serous cysts, serous borderline tumors, or low-grade serous carcinoma. They were differentially expressed in different types of ovarian carcinomas, being more often expressed at high levels in high-grade serous carcinoma, malignant mixed mullerian tumors and undifferentiated carcinoma, and more often expressed at low levels or not at all in clear cell and mucinous carcinomas. We concluded that IGFBP2 and IGFBP5 might play a role in the development of high-grade ovarian serous carcinoma, but not in mucinous or clear cell ovarian carcinomas.     

Immunohistochemical confirmation of pulmonary papillary adenocarcinoma metastatic to ovaries

Metastatic papillary adenocarcinomas of the ovary are rare compared to primary ovarian papillary serous carcinomas. We report a case of pulmonary papillary adenocarcinoma metastatic to the ovary and show how this tumor can be differentiated immunohistochemically from an ovarian primary. Paraffin blocks of the ovarian tumor were analyzed for carcinoembryonic antigen, CA 125, surfactant, E-cadherin, N-cadherin, and vimentin. These markers are useful in differentiating epithelial tumors of lung versus ovarian origin. The papillary tumor showed expression of carcinoembryonic antigen, surfactant, and E-cadherin, but was negative for CA 125, N-cadherin, and vimentin. These findings support a lung carcinoma metastatic to the ovary.     

Incidence of loss of heterozygosity at p53 and BRCA1 loci in serous surface carcinoma

Serous surface carcinoma (SSC) is a neoplasm histologically indistinguishable from typical serous carcinomas that arise from the ovary but has a distinct clinical presentation. It is characterized by widespread peritoneal dissemination at presentation, but the ovaries are grossly normal in size and shape. If the carcinoma involves the ovaries microscopically, the tumor is confined to the surface or is minimally invasive. The recognition of this entity is important, because in some studies it appears to have a poorer prognosis than stage-matched serous cancers of the ovary. Loss of heterozygosity (LOH) of the p53 (17p) and BRCA1 (17q) tumor suppressor genes has been frequently identified in sporadic ovarian carcinomas. Although 17p LOH is correlated with common p53 gene mutations, inactivating mutations of the BRCA1 gene are uncommon in sporadic ovarian cases. In contrast, germline BRCA1 mutations are responsible for some hereditary forms of ovarian cancer, where it has been suggested that germline BRCA1 mutations confer a more favorable prognosis. In this study, 12 sporadic SSC were assessed for the presence of allelic deletions on the p53 and BRCA1 gene loci. DNA from both tumor and normal cells was obtained for LOH studies using tissue microdissection. Polymerase chain reaction (PCR) amplification was performed with the polymorphic DNA markers TP53 (17p13.1/p53 gene) and D17S579 (17q/BRCA1 gene). LOH in the p53 and BRCA1 loci was detected in 62.5% and 66.6% of the cases, respectively. In 50% of tumors informative for both markers, it is possible that an entire chromosome may be lost. In conclusion, we have shown that LOH of the p53 and BRCA1 loci is a frequent event in sporadic SSC, similar to what has been described in the usual form of serous ovarian carcinoma. Mutational analysis will be necessary to determine the exact role of these genes in this group of tumors.     

Gene expression profiles of microdissected pancreatic ductal adenocarcinoma

In a search for new molecular markers of pancreatic ductal adenocarcinoma (PDAC), we compared the gene expression profiles of seven pancreatic carcinomas and one carcinoma of the papilla Vateri with those of duct cells from three non-neoplastic pancreatic tissues. In addition, the human pancreatic duct cell line and five PDAC cell lines (AsPC-1, BxPC-3, Capan-1, Capan-2, HPAF) were examined. RNA was extracted from microdissected tissue or cultured cell lines and analysed using a custom-made Affymetrix Chip containing 3023 genes, of which 1000 were known to be tumour associated. Hierarchical clustering revealed 81 differentially expressed genes. Of all the genes, 26 were downregulated in PDAC and 14 were upregulated in PDAC. In PDAC cell lines versus normal pancreatic duct cells, 21 genes were downregulated and 20 were upregulated. Of these 81 differentially expressed genes, 15 represented human genes previously implicated in the tumourigenesis of PDAC. From the genes that were so far not known to be associated with PDAC tumorigenesis, we selected ADAM9 for further validation because of its distinct overexpression in tumour tissue. Using immunohistochemistry, the over-expressed gene, ADAM9, was present in 70% of the PDACs analysed. In conclusion, using microarray technology we were able to identify a set of genes whose aberrant expression was associated with PDAC and may be used to target the disease.     

Mucosal carcinoma of the fallopian tube coexists with ovarian cancer of serous subtype only: a study of Japanese cases

Previous studies in Western countries have revealed that mucosal carcinoma of the fallopian tube frequently coexists with pelvic (ovarian, tubal, and peritoneal) serous carcinomas, and early tubal carcinoma is now regarded as a possible origin of these tumors. However, the relationship between early tubal carcinoma and non-serous ovarian cancer, such as clear cell adenocarcinoma, has not been studied in detail. In this study, we sought to examine the coexistence of mucosal carcinoma of the fallopian tube in Japanese ovarian cancer cases. We submitted the fallopian tubes in toto for histological examination in 52 ovarian carcinoma cases and three peritoneal serous carcinoma cases. The ovarian tumors included 12 serous adenocarcinomas, 23 clear cell adenocarcinomas, nine endometrioid adenocarcinomas, three mucinous adenocarcinomas, and four mixed epithelial carcinomas. Mucosal carcinoma of the fallopian tube did not coexist with non-serous adenocarcinoma (n = 40). In contrast, mucosal carcinoma of the fallopian tube was observed in six cases of ovarian serous adenocarcinoma and one case of peritoneal serous adenocarcinoma. In these cases, the p53 immunophenotypes were similar in tubal lesions and invasive ovarian or peritoneal carcinomas. Tumors were negative for p53 in four of seven cases, and one of the p53-negative serous adenocarcinomas showed low-grade morphology. We believe that some ovarian and peritoneal serous adenocarcinomas develop from early tubal carcinomas. However, it should be noted that early tubal carcinomas are not always p53-positive immunohistochemically. Finally, it is unlikely that early tubal lesions are involved in the carcinogenesis of clear cell adenocarcinoma and other non-serous adenocarcinomas.