Clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres: a novel member of the perivascular epithelioid clear cell family of tumors with a predilection for children and young adults

The perivascular epithelioid cell family of tumors (PEComas), defined by their co-expression of melanocytic and muscle markers, includes angiomyolipoma, lymphangioleiomyoma, and clear cell "sugar" tumors of the lung, pancreas, and uterus. We present seven cases of a unique and previously unrecognized tumor of children and young adults, which represents a new addition to the PEComa group of tumors. Culled from three institutions over a 50-year period, all cases occurred in or immediately adjacent to the ligamentum teres and falciform ligament. Six patients were female and one male; their ages ranged from 3 to 21 years (median, 11 yrs). Tumor sizes ranged from 5 to 20 cm (median, 8 cm). All cases consisted of clear to faintly eosinophilic spindled cells arranged in fascicular and nested patterns. The cells had small but distinct nucleoli and low mitotic activity. Immunohistochemically, all cases were positive with antibodies to gp100 protein (HMB-45) and negative for S-100 protein. In three of the seven cases studied immunohistochemically, the tumors expressed smooth muscle actin, melan-A, microphthalmia transcription factor (MiTF), and myosin, but not desmin. No expression of the TSC2 gene product, tuberin, was seen in three cases. One case studied cytogenetically disclosed a t(3;10). Follow-up data, available in six of seven cases (median duration, 18 mos), showed five patients to be free of disease and one to have a radiographically presumed lung metastasis. We think these tumors comprise a new entity for which we propose the term "clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres." The differential diagnosis of these tumors includes clear cell sarcoma of tendons and aponeuroses, leiomyosarcoma, and angiomyolipoma.

Genetic basis of cancer of the kidney: disease-specific approaches to therapy

Studies during the past two decades have shown that kidney cancer is not a single disease; it is made up of a number of different types of cancer that occur in this organ. Clear cell renal carcinoma is characterized by mutation of the VHL gene. The VHL gene product forms a heterotrimeric complex with elongin C, elongin B, and Cul-2 to target hypoxia-inducible factors 1 and 2alpha for ubiquitin-mediated degradation. VHL-/- clear cell renal carcinoma overexpresses epidermal growth factor receptor and transforming growth factor alpha. Both hypoxia-inducible factor 1alpha and the epidermal growth factor receptor are potential therapeutic targets in clear cell renal carcinoma. Studies of the hereditary form of renal cell carcinoma (RCC) associated with hereditary papillary renal carcinoma (HPRC) determined that the c-Met proto-oncogene on chromosome 7 is the gene for HPRC and for a number of sporadic papillary RCCs. The HPRC c-Met mutations are activating mutations in the tyrosine kinase domain of the gene. The gene for a new form of hereditary RCC (Birt Hogg Dubé syndrome) associated with cutaneous tumors, lung cysts, and colon polyps or cancer has recently been identified. Studies are currently under way to determine what type of gene BHD is and how damage to this gene leads to kidney cancer. Individuals affected with hereditary leiomyomatosis renal cell carcinoma are at risk for the development of cutaneous leiomyomas, uterine leiomyomas (fibroids), and type 2 papillary RCC. The HLRC gene has been found to be the Krebs cycle enzyme, fumarate hydratase. Studies are under way to understand the downstream pathway of this cancer gene.

Endometriosis and the neoplastic process

Endometriosis is a frequent disorder that commonly presents with infertility and pelvic pain. Although the precise aetiology of endometriosis is unclear, it is generally considered to involve multiple genetic, environmental, immunological, angiogenic and endocrine processes. Genetic factors have been implicated in endometriosis but the susceptibility genes remain largely unknown. Although endometriosis is a benign disorder, recent studies of endometriosis suggest endometriosis could be viewed as a neoplastic process. Evidence to support this hypothesis includes the increased susceptibility to develop ovarian clear-cell and endometrioid cancers in the presence of endometriosis, and molecular similarities between endometriosis and cancer. In this article we discuss (i) the evidence suggesting that endometriosis might be viewed as a neoplastic process, and (ii) the implications of this hypothesis for elucidating the pathogenesis of endometriosis and developing novel methods of diagnostic classification and individualised treatments.

Immunohistochemical detection of the Wilms' tumor gene (WT1) in epithelial ovarian tumors

The Wilms' tumor gene WT1 plays multiple roles in the development of the genitourinary organs and Wilms' tumors. The aims of this study were to immunohistochemically evaluate WT1 expression in normal female genital tissues and in epithelial ovarian tumors and to look for correlations between WT1 expression and histologic subtypes and cell proliferation in epithelial ovarian tumors. In normal female genital organs, WT1 expression was recognized in ovarian surface epithelium, the lining of inclusion cysts, and tubal epithelium, but not in the cervical or endometrial epithelium. In epithelial ovarian tumors, serous tumors generally revealed a high WT1 expression. Among adenocarcinomas, serous carcinoma revealed a significantly higher WT1 expression than the other histologic subtypes. There were no significant correlations between the WT1 labeling index and the Ki-67 labeling index, and no significant difference in survival between those showing high and low WT1 expression among the malignant cases. These results suggest that WT1 expression may be related to cell differentiation, and that the histologic subtypes of epithelial ovarian carcinomas may differ considerably in their biological characteristics.

KRAS and BRAF mutations in ovarian tumors: a comprehensive study of invasive carcinomas, borderline tumors and extraovarian implants

OBJECTIVE

Mutations of BRAF, a downstream mediator of K-RAS, have been described in serous borderline tumors of the ovary. Data concerning other types of ovarian tumors are scarce. Therefore, we assessed KRAS and BRAF mutation in a series of more than 100 different ovarian tumors.

METHODS

Paraffin-embedded material, including invasive carcinomas, borderline tumors, benign lesions and implants, was used. BRAF codon 600 in exon 15 and K-RAS codon 12 in exon 2 were analysed.

RESULTS

92 cases (92%), including all serous carcinomas (100%), did not show a mutation of BRAF. Eight cases (8.0%), including five serous borderline tumors (31.25%), contained a mutation. In all serous borderline tumors, codon 600 was affected. The remaining three cases were invasive carcinomas of endometrioid (mutation on codon 600), mucinous (mutation on codon 600) and clear cell (mutation on codon 615) subtype. There was no BRAF mutation in mucinous borderline tumors. Regarding K-RAS, 89 cases (87.25%) did not show an aberration. The 11 positive borderline tumors (10.7%) were of serous (22.2%) and of mucinous type (46.6%). There was a KRAS mutation in a serous and a mucinous invasive carcinoma each. BRAF and K-RAS mutations were mutually exclusive and not seen in implants.

CONCLUSION

Mutation of either K-RAS or BRAF is frequent in borderline tumors but is not found in invasive serous carcinomas and is very rare in other invasive subtypes. This supports the notion of different pathological pathways. For the development of extraovarian implants, further studies are observed.

Mutations in the BRCA1-associated RING domain (BARD1) gene in primary breast, ovarian and uterine cancers

Germline alterations of BRCA1 result in susceptibility to breast and ovarian cancer. The protein encoded by BRCA1 interacts in vivo with the BRCA1-associated RING domain (BARD1) protein. Accordingly, BARD1 is likely to be a critical factor in BRCA1-mediated tumor suppression and may also serve as a target for tumorigenic lesions in some human cancers. We have now determined the genomic structure of BARD1 and performed a mutational analysis of 58 ovarian tumors, 50 breast tumors and 60 uterine tumors. Seven polymorphisms were detected within the 2.34 kb coding sequence of BARD1 . Somatically acquired missense mutations were observed in one breast carcinoma and one endometrial tumor; in at least one of these cases, tumor formation was accompanied by loss of the wild-type BARD1 allele, following the paradigm for known tumor suppressor genes. In addition, a germline alteration of BARD1 was identified in a clear cell ovarian tumor (Gln564His); again, loss of the wild-type BARD1 allele was observed in the malignant cells of this patient. The Gln564His patient was also diagnosed with two other primary cancers: a synchronous lobular breast carcinoma and a stage IA clear cell endometrioid cancer confined to an endometrial polyp 6 years earlier. These findings suggest an occasional role for BARD1 mutations in the development of sporadic and hereditary tumors.

Strict regulation of CAIX(G250/MN) by HIF-1alpha in clear cell renal cell carcinoma

Renal cell carcinoma of the clear cell type (ccRCC) is associated with loss of functional von Hippel-Lindau (VHL) protein and high, homogeneous expression of the G250MN protein, an isoenzyme of the carbonic anhydrase family. High expression of G250MN is found in all ccRCCs, but not in most normal tissues, including normal human kidney. We specifically studied the mechanism of transcriptional regulation of the CAIXG250 gene in RCC. Previous studies identified Sp1 and hypoxia-inducible factor (HIF) as main regulatory transcription factors of G250MN in various non-RCC backgrounds. However, G250MN regulation in RCC has not been studied and may be differently regulated in view of the HIF accumulation under normoxic conditions due to VHL mutations. Transient transfection of different G250MN promoter constructs revealed strong promoter activity in G250MN -positive RCC cell lines, but no activity in G250MN -negative cell lines. DNase-I footprint and band-shift analysis demonstrated that Sp1 and HIF-1alpha proteins in nuclear extracts of RCC cells bind to the CAIX promoter and mutations in the most proximal Sp1 binding element or HIF binding element completely abolished CAIX promoter activity, indicating their critical importance for the activation of G250 expression in RCC. A close correlation between HIF-1alpha expression and G250MN expression was observed. In contrast, no relationship between HIF-2alpha expression and G250MN was seen. The participation of cofactor CBP/p300 in the regulation of G250 transcription was shown. In conclusion, HIF-1alpha and Sp1, in combination with CBP/p300, are crucial elements for G250MN expression in ccRCC, and CAIXG250 can be regarded as a unique HIF-1alpha target gene in ccRCC.

Association of decreased mitochondrial DNA content with ovarian cancer progression

Mitochondrial DNA (mtDNA) content in ovarian carcinomas was assessed by quantitative PCR. Results show that mtDNA content in tumour cell was significantly higher than that in normal ovary. Change in mtDNA content was not related with patients' age or tumour stages. However, the average mtDNA copy number in pathological low-grade tumours was over two-fold higher than that in high-grade carcinomas (P=0.012). Moreover, type I carcinomas also had a significantly higher mtDNA copy number than in type II carcinomas (P=0.019). Change in mtDNA content might be an important genetic event in the progression of ovarian carcinomas.

Genotype-phenotype correlation in von Hippel-Lindau syndrome

The von Hippel-Lindau (VHL) syndrome (OMIM 193300) is an autosomal dominant disorder caused by deletions or mutations in a tumor suppressor gene on human chromosome 3p25. It is characterized clinically by vascular tumors including benign hemangioblastomas of the cerebellum, spine, brain stem and retina. Clear-cell renal cell carcinoma is a frequent cause of death, occurring in up to 70% of patients with VHL. Pheochromocytomas occur in association with specific alleles (usually mutations as opposed to deletions), therefore a family history of pheochromocytoma in association with VHL is an indication for thorough surveillance for pheochromocytoma in affected family members. The VHL gene coding sequence contains three exons. Two isoforms of mRNA exist, reflecting the presence or absence of exon 2. Tumors arise following the loss or inactivation of the wild-type allele in a cell. In initial studies approximately 20% of patients had large germline mutations detectable by Southern blot analysis, 27% had missense mutations and 27% had nonsense or frameshift mutations. Advances in mutation analysis now allow for a 100% mutation detection rate in families with definite VHL. Families may be characterized by the presence [type 2 (7-20% of families)] or absence (type 1) of pheochromocytomas. Most type 2 families are affected by missense mutations, whereas most type 1 families have deletions or premature termination mutations. The prognosis for the lifetime risk of pheochromocytoma can be estimated by determination of the underlying mutation even if there is no family history of VHL.

PTEN mutations in endometrial carcinomas: a molecular and clinicopathologic analysis of 38 cases

PTEN mutations have been reported to be frequent in endometrioid carinomas of the endometrium (EEC). Some correlation has been found between PTEN mutations and the presence of microsatellite instability (MI) in EEC, but no convincing cause-effect relationship for such association has been offered. DNA of 38 patients with endometrial carcinoma (EC) was extracted from blood and from fresh-frozen and paraffin-embedded tumor tissue. PTEN mutations were detected by single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. Results were correlated with MI status and clinicopathologic data. PTEN mutations were detected in 17 tumors (44.7%), and they were more frequent in endometrioid (EEC) (17 of 33, 51.5%) than in nonendometrioid carcinomas (NEEC) (0 of 5, 0%). PTEN mutational spectrum differed between MI+ and MItumors. PTEN mutations were detected in 9 of 15 MI+ tumors (60%), but in only 8 of 23 MI- neoplasms (34.8%). In EC with MI, PTEN mutations were detected in short coding mononucleotide repeats (A)s and (A)6 in 4 of 9 carcinomas (44.4%). These results confirm that PTEN is an important target gene in endometrial carcinogenesis. The occurrence of PTEN mutations in short coding mononucleotide repeats in MI-positive tumors suggests that these mutations may be secondary to deficiencies in mismatch repair and gives some explanation for the frequent presence of PTEN mutations in these tumors.

Molecular genetic evidence that endometriosis is a precursor of ovarian cancer

Histopathology and epidemiology studies have consistently demonstrated a strong link between endometriosis and endometriosis-associated ovarian cancers (EAOCs)--in particular, the endometrioid and clear cell subtypes. However, it is still unclear whether endometriosis is a precursor to EAOCs, or whether there is an indirect link because similar factors predispose to both diseases. In order to search for evidence of clonal progression, we analyzed 10 EAOCs (endometrioid=4; clear cell=6) with coexisting endometriosis for common molecular genetic alterations in both the carcinoma and corresponding endometriosis. We used 82 microsatellite markers spanning the genome to examine loss of heterozygosity (LOH) in the coexisting carcinoma and endometriosis samples. A total of 63 LOH events were detected in the carcinoma samples; twenty two of these were also detected in the corresponding endometriosis samples. In each case, the same allele was lost in the endometriosis and cancer samples. Interestingly, no marker showed LOH in the endometriosis alone. These data provide evidence that endometriosis is a precursor to EAOCs.

Primary cilium formation requires von hippel-lindau gene function in renal-derived cells

Biallelic inactivation of the von Hippel-Lindau tumor suppressor gene, VHL, occurs in the majority of renal clear cell carcinomas (RCC). VHL's function, regulating the degradation of hypoxia-inducible factor alpha (HIFalpha) subunits, explains the angiogenic nature of these tumors, but not tumor initiation. Because the development of renal cysts precedes tumor formation, and because the dysfunction of primary cilium is a common pathogenic mechanism in polycystic kidney diseases, we determined whether kidney-derived VHL- cells required VHL for the generation of cilium. Ectopic expression of VHL in RCC(VHL-) cells induced increased polarization and primary cilium formation. Cilium formation correlated directly with the expression of both wild-type VHL isoforms and a VHL mutant not associated with RCC development, whereas expression of RCC-associated VHL mutants did not support ciliogenesis. Requirement of VHL for ciliogenesis was independent of HIFalpha abundance. These data indicate separable independent functions for VHL (HIFalpha degradation and differentiation) and suggest a mechanism whereby disruption of both functions is required for renal carcinogenesis.

Biology of Epithelial Ovarian Cancer: Implications for Screening Women at High Genetic Risk

Purpose

Our aim was to analyze the clinicopathologic features of screen-detected ovarian cancers identified in women, either at general population risk or high genetic risk of ovarian cancer, who have participated in screening studies.

Methods

Studies published between 1988 and April 2003 were categorized by the population screened and the primary screening modalities used. Each report was examined with reference to the histologic type, stage, and grade of screen-detected cancers. Reports of studies of prophylactically removed ovaries from women at high risk of ovarian cancer were also reviewed.

Results

Of the stage I tumors detected by screening women at population risk, almost half were borderline ovarian tumors, granulosa-cell tumors, or germ-cell tumors, which is disproportionate to their frequency. Furthermore, of the stage I invasive epithelial cancers diagnosed in women at population risk, the majority were endometrioid, clear-cell, and mucinous histologic subtypes. Most ovarian cancers that occur in women at high genetic risk are high-grade serous cancers, and these are infrequently screen detected at an early stage.

Conclusion

The clinicopathologic features of screen-detected ovarian cancers suggest that screening may not reduce mortality in women at increased genetic risk. Prospective screening studies are required in genetically high-risk populations to answer this important question. Women electing surveillance should be aware of the lack of proven benefit and the low likelihood of detecting early stage serous cancers. Bilateral salpingo-oophorectomy appears to be the most effective approach to decrease the risk of ovarian cancer and thereby reduce mortality in high-risk women.

HER-2/neu amplification and overexpression in endometrial carcinoma

HER-2/neu is a proto-oncogene associated with poor prognosis in women with breast and ovarian carcinoma. The significance of HER-2/neu in endometrial carcinoma is less clearly established. The authors compared HER-2/neu gene amplification using fluorescence in situ hybridization and protein overexpression using immunohistochemistry with survival in patients with endometrial carcinoma. Fluorescence in situ hybridization and immunohistochemical staining were performed on 72 formalin-fixed, paraffin-embedded endometrial carcinoma specimens. Vysis combination HER-2/neu and centromere 17 probe mixture was applied to isolated tumor cell nuclei. A minimum of 200 nuclei were scored for each specimen using standard signal enumeration criteria. A specimen was considered amplified with 5% or greater amplified nuclei. Tissue sections were immunostained with polyclonal antibody against p185erb-2 transmembrane glycoprotein. Immunohistochemical reactivity was scored on a three-tiered scale. HER-2/neu gene amplification and protein overexpression were detected in 15 of 72 (21%) and 12 of 72 (17%) of the specimens, respectively, with 2 cases of normal copy overexpression and 5 cases of amplification without overexpression. Both amplification and overexpression were associated with higher grade tumors. Amplification was associated with clear cell and serous subtypes (p = 0.002), and overexpression with only clear cell type (p = 0.006). Using the proportional hazards model of survival, amplification was found to have significant negative predictive value beyond stage, grade, and cell type (p = 0.002). HER-2/neu gene amplification as detected by fluorescence in situ hybridization in archival material has significant prognostic value.

Expression of serum miR-200a, miR-200b, and miR-200c as candidate biomarkers in epithelial ovarian cancer and their association with clinicopathological features

BACKGROUND

MicroRNAs (miRs) have been implicated in the etiology of various human cancers. The aim of this study was to investigate the association of the expression of three members--miR 200a, miR 200b, and miR 200c belonging to the miR-200 family with clinicopathological characteristics and their impact on the progression of epithelial ovarian cancer (EOC).

MATERIALS AND METHODS

Total RNA from serum was isolated by Trizol method, polyadenylated, and reverse transcribed into cDNA. Expression levels of miR-200a, miR-200b, and miR-200c were detected by using miRNA qRT-PCR. We measured miR expression in 70 serum samples of EOC patients with matched controls using U6 snRNA as a reference. Levels of miR expression was compared with distinct clinicopathological features.

RESULTS

Expression of miR-200a was found to be greater than six-fold (p = 0.01), miR-200b and miR-200c greater than three-fold (p = 0.01) in comparison with matched normal controls. Association of miRNA expression with clinicopathological factors and progression was statistically evaluated. The expression levels of miR-200a and miR-200c were found to be significantly associated with disease progression (p = 0.04 and p < 0.001, respectively). miR-200a overexpression was found be associated with tumor histology and stage. Patients with lymph node metastasis showed significant elevation of miR-200c (p = 0.006). The AUC in ROC curve also indicated that serum levels of miR-200a and miR-200c might be worthwhile as a diagnostic tool in the near future.

CONCLUSION

Our findings suggest that miR-200a, miR-200b, and miR-200c overexpressions are associated with the aggressive tumor progression and be recognized as reliable markers to predict the prognosis and survival in EOC patients.

Unique Gene Expression Profile Based on Pathologic Response in Epithelial Ovarian Cancer

Purpose

We investigated whether tumor tissue obtained at diagnosis expresses a specific gene profile that is predictive of findings at second-look surgery in patients with epithelial ovarian cancer (EOC).

Patients and Methods

Tumor tissue obtained at the time of diagnosis was profiled with oligonucleotide microarrays. Class prediction analysis was performed in a training set of 24 patients who had undergone a second-look procedure. The resultant predictive signature was then tested on an independent validation set comprised of 36 patients.

Results

A 93-gene signature referred to as the Chemotherapy Response Profile (CRP) was identified through its association with pathologic complete response. When applied to a separate validation set, the CRP distinguished between patients with unfavorable versus favorable overall survival (median 41 months v not yet reached, respectively, log-rank P = .007), with a median follow-up of 52 months. The signature maintained independent prognostic value in multivariate analysis, controlling for other known prognostic factors such as age, stage, grade, and debulking status. There was no genetic overlap between the CRP and our previously described Ovarian Cancer Prognostic Profile (OCPP), which demonstrated similar prognostic value. The combination of the CRP and OCPP yielded better prognostic discrimination then either profile alone. Genes present in the CRP include BAX, a proapoptotic protein previously associated with chemotherapy response in ovarian cancer.

Conclusion

Identification of a gene expression profile based on pathologic response in EOC provides independent prognostic information and offers potential insights into the mechanism of drug resistance. Efforts to identify a more tailored profile using selected genes from both the CRP and OCPP are underway.

Possible involvement of hMLH1, p16(INK4a) and PTEN in the malignant transformation of endometriosis

Endometriosis is a common gynecologic disease, which generally follows a benign course. Notwithstanding, several clinical and histologic studies as well as molecular data show that endometriosis could be a precursor of sporadic endometrioid and clear cell carcinomas at extrauterine loci. Several reports have implicated alterations of the hMLH1 and p16(ink4a) (p16) genes, in particular hypermethylation of the promoter region, and of the PTEN gene, principally genetic mutations, in endometrial and ovarian cancers and have indicated that these alterations are already present in precancer conditions. In this report, we analyzed the methylation status of hMLH1 and p16 and the protein expression of PTEN and hMLH1 in 46 cases of endometriosis stages III and IV to better define the possible involvement of these genes in the malignant transformation of endometriosis. We found abnormal methylation of hMLH1 in 4 of the 46 cases (8.6%). In addition, these cases had no detectable hMLH1 protein expression. Regarding patients with hMLH1 alterations, 2 were classified as stage IV and 2 showed coexistent endometriosis and carcinoma. Only 1 case of endometriosis (2.17%), classified as atypical, showed abnormal methylation of p16. Reduced PTEN protein expression was detected in 7 of 46 cases (15.21%): 5 were clinically classified as stage IV, and the other 2 presented both cancer and hypermethylated hMLH1. Our preliminary study suggests that reduced expression of both hMLH1 and PTEN may be involved in the malignant evolution of endometriosis and should be used as markers of neoplastic transformation in aggressive endometriosis with elevated tumor markers.

A phase II and pharmacodynamic study of gefitinib in patients with refractory or recurrent epithelial ovarian cancer

BACKGROUND

The primary objective of this study was to evaluate the biochemical effects of gefitinib on its target signal-transduction pathways in patients with recurrent epithelial ovarian cancer (EOC). The secondary objectives included assessing clinical activity and toxicity and determining the association between biochemical and clinical outcomes.

METHODS

Twenty-four heavily pretreated patients with EOC who had good end-organ function and performance status and who had measurable disease received gefitinib 500 mg daily. Prospectively planned core-needle tumor biopsies were obtained before treatment and after 4 weeks. Protein expression of total and phosphorylated (p) epidermal growth factor receptor (EGFR), protein kinase B (AKT), and extracellular regulated kinase (ERK) was quantified in microdissected tumor cells using tissue lysate array proteomics.

RESULTS

All tumor samples had detectable levels of EGFR and p-EGFR. A decrease in the quantity of both EGFR and p-EGFR was observed with gefitinib therapy in >50% of patients. This was not associated with clinical benefit, nor were responses observed. However, trends for increased gastrointestinal and skin toxicity were observed with greater phosphorylation or quantities of EGFR, ERK, and AKT in tumor samples (P </= .05). Gefitinib had limited clinical activity as monotherapy despite documented target inhibition.

CONCLUSIONS

The results from this study demonstrated that gefitinib inhibited the phosphorylation of EGFR in EOC tumor cells, providing proof of target in a clinical setting. Combinatorial therapy with molecular therapeutics against complementary targets may prove successful.

Microsatellite instability and alteration of the expression of hMLH1 and hMSH2 in ovarian clear cell carcinoma

Microsatellite instability (MSI) is commonly seen in tumors associated with the hereditary nonpolyposis colorectal cancer syndrome and is caused by defects in the DNA mismatch repair genes. MSI has also been observed in various sporadic cancers, including colorectal, gastric, and endometrial. The role and incidence of MSI in ovarian clear cell carcinoma remain unknown. This study was conducted to evaluate the frequency of MSI in ovarian clear cell carcinomas and to evaluate the sensitivity and specificity of immunohistochemistry in predicting mismatch-repair gene deficiency. A total of 42 ovarian clear cell carcinomas were analyzed for MSI using a panel of 5 microsatellite markers (BAT25, BAT26, D5S346, D2S123, and D17S250). Alterations in the expression of hMLH1 and hMSH2 proteins in these tumors were examined. Of the 42 ovarian clear cell tumors analyzed, 6 demonstrated a high level of MSI (MSI-H), 3 demonstrated a low level of MSI (MSI-L), and the remaining 33 exhibited microsatellite stability (MSS). No correlation was found between MSI level and patient age or tumor stage or size (P >0.05). Loss of expression of either hMLH1 or hMSH2 was observed in 4 of the 6 (67.7%) MSI-H tumors, whereas 34 of the 36 (94.4%) MSI-L or MSS tumors expressed both the hMLH1 and hMSH2 gene products. Our results indicate that MSI-H is involved in the development of a subset of ovarian clear cell carcinomas. A strong correlation exists between alterations in the expression of hMLH1 and hMSH2 and the presence of MSI-H in these tumors. However, immunohistochemical testing alone may miss a small fraction of cases with MSI-H.

Tumor Suppressor Activity and Epigenetic Inactivation of Hepatocyte Growth Factor Activator Inhibitor Type 2/SPINT2 in Papillary and Clear Cell Renal Cell Carcinoma

Following treatment with a demethylating agent, 5 of 11 renal cell carcinoma (RCC) cell lines showed increased expression of hepatocyte growth factor (HGF) activator inhibitor type 2 (HAI-2/SPINT2/Bikunin), a Kunitz-type protease inhibitor that regulates HGF activity. As activating mutations in the MET proto-oncogene (the HGF receptor) cause familial RCC, we investigated whether HAI-2/SPINT2 might act as a RCC tumor suppressor gene. We found that transcriptional silencing of HAI-2 in RCC cell lines was associated with promoter region methylation and HAI-2/SPINT2 protein expression was down-regulated in 30% of sporadic RCC. Furthermore, methylation-specific PCR analysis revealed promoter region methylation in 30% (19 of 64) of clear cell RCC and 40% (15 of 38) of papillary RCC, whereas mutation analysis (in 39 RCC cell lines and primary tumors) revealed a missense substitution (P111S) in one RCC cell line. Restoration of HAI-2/SPINT2 expression in a RCC cell line reduced in vitro colony formation, but the P111S mutant had no significant effect. Increased cell motility associated with HAI-2/SPINT2 inactivation was abrogated by treatment with extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phospholipase C-gamma inhibitors, but not by an inhibitor of atypical protein kinase C. These findings are consistent with frequent epigenetic inactivation of HAI-2/SPINT2, causing loss of RCC tumor suppressor activity and implicate abnormalities of the MET pathway in clear cell and papillary sporadic RCC. This information provides opportunities to develop novel targeted approaches to the treatment of RCC.

Molecular carcinogenesis of endometrial cancer

In 1983, Bokhman proposed a dualistic model of endometrial tumorigenesis based on the clinical observations and clinicopathologic correlations. The majority of endometrial cancers (approximately 70-80%), designated as type I carcinomas, follow the estrogen-related pathway. Histologically, most of the type I tumors seem to arise in the background of hyperplastic endometrium, show an endometrioid differentiation, and are of low grade. Clinically, they are overall characterized by a favorable behavior. Another 10-20% of endometrial cancers, designated as type II carcinomas, follow the estrogen-unrelated pathway and arise in the background of atrophic endometrium. Type II tumors usually occur at an older age, approximately 5-10 years later than type I tumors. They are typically high-grade carcinomas of nonendometrioid differentiation, most frequently serous, less frequently clear cell. Type II carcinomas behave as an aggressive clinical course and poor prognosis. This dualistic model was subsequently supported by the molecular studies, approximately a decade later. At present, endometrioid and serous carcinoma, which represent the major phenotypes of types I and II endometrial carcinomas, respectively, are characterized by distinctive types of genetic instability and molecular alterations. In endometrioid (type I) carcinoma, four major genetic changes are responsible for the tumorigenesis, i.e. silencing of PTEN tumor suppressor gene, presence of microsatellite instability due to alterations of the mismatch repair genes, mutation of K-ras protooncogene, and alteration of beta-catenin gene. On the other hand, p53 mutation and overexpression of Her2/neu oncogene are two major genetic alterations in serous and clear cell (type II) carcinomas. However, like in any model, there is evidence for exceptions. Many endometrial carcinomas are in the gray zone with overlapping clinical, morphologic, immunohistochemical, and molecular features of types I and II endometrial cancers. Finally, a small group of endometrial carcinoma is noted to be hereditary. It is known as the most common extracolonic malignancy in hereditary nonpolyposis colorectal cancer (Lynch syndrome), an autosomal dominantly inherited disorder of cancer susceptibility. Inactivation of the mismatch repair genes MSH2 and MSH6 seems to play a central role in the tumorigenesis.

Alternate molecular genetic pathways in ovarian carcinomas of common histological types

We evaluated alterations in p53, PIK3CA, PTEN, CTNNB1 (beta-catenin), MLH1, and BRAF among common histological subsets of epithelial ovarian tumors to characterize patterns of alterations of different molecular pathways. There were 12 clear cell, 26 endometrioid, and 51 serous carcinomas evaluated by direct DNA sequencing for mutations in p53, PIK3CA, PTEN, BRAF, and CTNNB1. Methylation-specific polymerase chain reaction (PCR) assessed MLH1 promoter methylation status. Quantitative PCR identified PIK3CA amplification in 22 EC/CC and 94 SC. p53 mutations were identified in 25 (49%) of 51 SC, 11 (42%) of 26 EC, and 1 (8.3%) of 12 CC neoplasms and were more common in grade 3 EC (P = .045) and advanced-stage EC/CC (P = .007). PIK3CA mutations were identified in 3 (25%) of 12 CC, 3 (12%) of 26 EC, and 0 of 51 SC. PTEN mutations were significantly more common in EC (8/26, 31%) compared with CC (0/12; P = .04) and SC (2/51, 4%; P = .002). CTNNB1 mutations were identified, 6 (23%) EC and no CC or SC (P = .008). Both PTEN and CTNNB1 mutations were more common in low-grade EC/CC, whereas PIK3CA mutations occurred only in grade 3 cancers. PTEN and PIK3CA mutations were more common in p53 wild-type tumors (P = .003). PIK3CA amplification occurred in fewer EC/CC (0/22) versus SC (19/94, 20%; P = 0.02) and were slightly more common in p53 wild-type compared with p53 mutant SC (P = .08). Of 26 EC, 22 (85%) had a mutation in one of the genes studied compared with 4 33% of 12 CC (P = .003). Women with EC/CC had significantly better overall survival (P = .0008), and this remained significant after accounting for stage (P=.04). Mutations in p53 or in PTEN/PIK3CA are alternative pathways in ovarian carcinogenesis. Activation of PIK3CA occurs by gene amplification in SC but via somatic mutation of PIK3CA or PTEN in EC and CC. PIK3CA mutations are associated with high-grade tumors, whereas PTEN and CTNNB1 mutations are associated with low-grade tumors. Mutations in p53, PIK3CA, PTEN, and CTNNB1 account for most EC tumors; most CC remain unexplained. EC/CC histology is a favorable prognostic factor.

Ovarian clear cell adenocarcinoma: a continuing enigma

Ovarian clear cell adenocarcinomas (OCCAs) account for <5% of all ovarian malignancies. Compared to other epithelial ovarian cancer (EOC) subtypes, when at an advanced stage, they are associated with a poorer prognosis and are relatively resistant to conventional platinum-based chemotherapy. By contrast, early-stage clear cell ovarian cancer carries a relatively good prognosis. Hence, there is a need to improve our understanding of its pathobiology in order to optimise currently available treatments and develop new therapeutic strategies. This review summarises the currently available literature regarding the pathogenesis of OCCA, its molecular genetic features and postulated molecular mechanisms that underlie its chemoresistant phenotype. Marked similarities with clear cell carcinomas of the kidney and endometrium have been noted by some investigators, raising interesting possibilities regarding novel therapeutic approaches. Unfortunately, most studies on OCCA have hitherto been hampered by insufficient sample sizes, leaving many key issues unresolved. It is envisaged that in the future, high-resolution genomic and gene-expression microarray studies incorporating larger sample sizes will lead to the characterisation of the key molecular players in OCCA biology, which may potentially lead to the identification of novel targets for therapeutic development.

Fusion of the EWSR1 and ATF1 genes without expression of the MITF-M transcript in angiomatoid fibrous histiocytoma

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor that usually occurs in children and young adults. Only two cases of AFH with genetic rearrangements have been reported previously; both of these had a FUS-ATF1 fusion gene. We have studied an AFH from a 9-year-old boy whose tumor displayed a t(12;22)(q13;q12) as the sole cytogenetic aberration. FISH,RT-PCR, and sequence analyses revealed an EWSR1-ATF1 fusion gene that has previously been reported in clear cell sarcoma (CCS), a soft tissue sarcoma that is morphologically and clinically distinct from AFH. This study thus has demonstrated that the EWSR1-ATF1 chimera represents a fusion gene that can be associated with different tumor types. Simultaneous expression of the EWSR1-ATF1 and MITF-M transcripts in CCS has led to the proposal that the MITF-M promoter is transactivated by EWSR1-ATF1. The AFH, however, did not express the MITF-M transcript, supporting the theory that MITF-M expression in CCS is a reflection of its cellular origin, rather than a consequence of the presence of an EWSR1-ATF1 fusion protein. Activation of the EWSR1-ATF1 oncogene is probably an early step in the transformation process, but the overall gene expression patterns are likely to vary considerably between AFH and CCS, in keeping with their clinicopathologic differences.

Clinicopathological significance of loss of ARID1A immunoreactivity in ovarian clear cell carcinoma

Recent genome-wide analysis has demonstrated that somatic mutations in ARID1A (BAF250) are the most common molecular genetic changes in ovarian clear cell carcinoma (OCCC). ARID1A mutations, which occur in approximately half of OCCC cases, lead to deletion of the encoded protein and inactivation of the putative tumor suppressor. In this study, we determined the significance of loss of ARID1A immunoreactivity with respect to several clinicopathological features in a total of 149 OCCCs. First, we demonstrated that ARID1A immunohistochemistry showed concordance with the mutational status in 91% of cases with 100% sensitivity and 66% specificity. Specifically, among 12 OCCC cases for which ARIDA mutational status was known, ARIDIA immunoreactivity was undetectable in all 9 cases harboring ARID1A mutations and was undetectable in one of 3 cases with wild-type ARID1A. With respect to the entire cohort, ARID1A immunoreactivity was undetectable in 88 (59%) of 149 OCCCs. There was no significant difference between ARID1A negative and positive cases in terms of histopathologic features, age, clinical stage, or overall survival. In conclusion, this study provides further evidence that mutations in ARID1A resulted in loss of ARID1A protein expression in OCCC, although no significant differences between ARID1A positive and negative cases were observed with respect to any clinicopathological features examined.