The contribution of genetic and epigenetic changes in granulosa cell tumors of ovarian origin

Mismatch Repair Deficiency in Adult Granulosa Cell Tumors: an Immunohistochemistry-based Preliminary Study

OBJECTIVE

Adult granulosa cell tumors (AGCTs) are rare ovarian malignant neoplasms; their etiopathogenetic mechanisms remain largely unelucidated. Lately, defects in mismatch repair (MMR) have been implicated in the pathogenesis of AGCTs. Demonstration of MMR deficiency in these tumors can help identify patients potentially eligible for immune checkpoint inhibition therapy. The present study was done to explore the role of MMR deficiency in the etiopathogenesis of AGCTs.

METHODS

This was a retrospective study conducted on histopathologically confirmed AGCT cases. MMR protein expression was evaluated by immunohistochemistry (IHC) on tissue microarrays using an antibody panel of MSH2, MSH6, MLH1, and PMS2.

RESULTS

Of a total of 40 ovarian AGCTs evaluated for MMR deficiency, none demonstrated loss of expression of any of the 4 MMR proteins.

CONCLUSIONS

The results of our preliminary study show that there is no association between MMR deficiency with AGCT. Nevertheless, larger multicenter studies are needed to confirm or refute this observation.

Cytogenetic features of buccal epithelium under exposure to harmful factors of metallurgical production

At the present stage of development of society, the issues of preserving and strengthening the most important productive force that determine the economic development and national security of the country remain relevant. Metallurgy is one of the basic industries in Russia, which forms up to 20% of GDP. This study assesses the condition of the oral mucosa in workers in the industry. To evaluate the formation of micronuclei in buccal cells as an early biomarker of health disorders as a result of occupational exposure to production factors of a metallurgical plant. Hygienic and clinical laboratory tests were carried out for workers of the metallurgical plant of the Republic of Bashkortostan. Cytological studies of the buccal epithelium were performed. Statistical processing of the results was carried out using the applied programs IBM, SPSS, Statistics, Microsoft Excel. The general assessment of working conditions in accordance with the criteria of R.2.2.2006-05 for workers of the metallurgical plant was established as 3.2-3.3. Analysis of the buccal epithelium revealed the occurrence of cells with cytogenetic disorders in the workers of the main group. Cells with atypical nuclei were identified in workers with a duration of contact with unfavorable factors of production for more than ten years. Signs of nuclear destruction were revealed, characterizing an increase in apoptotic activity in workers with prolonged contact times. Studies have shown that with more than 10 years of work experience, proliferation processes prevail over differentiation processes. The results obtained can be used as diagnostic methods that expand the prospects for identifying pre-pathological and pathological conditions.

Gynecological Cancers Caused by Deficient Mismatch Repair and Microsatellite Instability

Mutations in mismatch repair genes leading to mismatch repair (MMR) deficiency (dMMR) and microsatellite instability (MSI) have been implicated in multiple types of gynecologic malignancies. Endometrial carcinoma represents the largest group, with approximately 30% of these cancers caused by dMMR/MSI. Thus, testing for dMMR is now routine for endometrial cancer. Somatic mutations leading to dMMR account for approximately 90% of these cancers. However, in 5-10% of cases, MMR protein deficiency is due to a germline mutation in the mismatch repair genes MLH1, MSH2, MSH6, PMS2, or EPCAM. These germline mutations, known as Lynch syndrome, are associated with an increased risk of both endometrial and ovarian cancer, in addition to colorectal, gastric, urinary tract, and brain malignancies. So far, gynecological cancers with dMMR/MSI are not well characterized and markers for detection of MSI in gynecological cancers are not well defined. In addition, currently advanced endometrial cancers have a poor prognosis and are treated without regard to MSI status. Elucidation of the mechanism causing dMMR/MSI gynecological cancers would aid in diagnosis and therapeutic intervention. Recently, a new immunotherapy was approved for the treatment of solid tumors with MSI that have recurred or progressed after failing traditional treatment strategies. In this review, we summarize the MMR defects and MSI observed in gynecological cancers, their prognostic value, and advances in therapeutic strategies to treat these cancers.

Quantitative assessment of aberrant P16INK4a methylation in ovarian cancer: a meta-analysis based on literature and TCGA datasets

Epigenetic alteration of P16^INK4a is conventionally thought to induce the initiation of carcinoma. However, the role of P16^INK4a methylation in ovarian cancer still remains controversial. Therefore, we performed a meta-analysis to further elucidate the relationship between P16^INK4a promoter methylation and ovarian cancer. A total of 24 studies, including 20 on risk, 10 on clinicopathological features, and 3 on prognosis, were included in our meta-analysis. Our results indicated that the frequency of P16^INK4a methylation in cancer tissues was significantly higher than normal tissues and low malignant potential tumor tissues (odds ratio [OR] =5.01, 95% CI=1.55–16.14; OR =1.88, 95% CI=1.10–3.19, respectively), but similar to benign tissues (OR =1.18, 95% CI=0.52–2.65). Furthermore, P16^INK4a promoter methylation was not strongly correlated with age, clinical stage, tumor differentiation, or histological subtype in patients with ovarian cancer. Additionally, survival analysis showed that patients with P16^INK4a promoter methylation had a shorter progression-free survival in univariate and multivariate Cox regression models (hazard ratio =1.68, 95% CI=1.26–2.24; hazard ratio =1.55, 95% CI=1.15–2.08; respectively). In The Cancer Genome Atlas datasets, the methylation levels of seven out of nine CpG sites were significantly increased in the ovarian tumor tissues compared with the normal tissues. In conclusion, the present meta-analysis suggests that P16^INK4a promoter methylation may be useful in distinguishing malignant cancer from healthy ovarian tissues, and it may be a potential predictive marker for prognosis in patients with ovarian cancer.

Blood free-circulating DNA testing by highly sensitive methylation assay to diagnose colorectal neoplasias

Although methylated TWIST1 is a biomarker of colorectal neoplasia, its detection from serum samples is very difficult by conventional bisulfite-based methylation assays. Therefore, we have developed a new methylation assay that enables counting of even one copy of a methylated gene in a small DNA sample amount without DNA bisulfite treatment. We performed this study to evaluate the sensitivity and specificity of serum DNA testing by the new methylation assay in combination with and without the fecal immunochemical test for hemoglobin for the detection of colorectal neoplasia. This study comprised 113 patients with colorectal neoplasia and 25 control individuals. For the new methylation assay, DNA was treated in two stages with methylation-sensitive restriction enzymes, followed by measurement of copy numbers of hTERT and methylated TWIST1 by multiplex droplet digital PCR. The fecal immunochemical test had a sensitivity of 8.0% for non-advanced adenoma, 24.3% for advanced adenoma, and 44.4% for colorectal cancer, and a specificity of 88.0%. The new assay had a sensitivity of 36.0% for non-advanced adenoma, 30.0% for advanced adenoma, and 44.4% for colorectal cancer, and a specificity of 92.0%. Combination of the both tests increased the sensitivity to 40.0%, 45.7%, and 72.2% for the detection of non-advanced adenoma, advanced adenoma, and colorectal cancer, respectively, and resulted in a specificity of 84.0%. Combination of both tests may provide an alternative screening strategy for colorectal neoplasia including potentially precancerous lesions and colorectal cancer.

Inhibition of non-homologous end joining in Fanconi Anemia cells results in rescue of survival after interstrand crosslinks but sensitization to replication associated double-strand breaks

When Fanconi Anemia (FA) proteins were depleted in human U2OS cells with integrated DNA repair reporters, we observed decreases in homologous recombination (HR), decreases in mutagenic non-homologous end joining (m-NHEJ) and increases in canonical NHEJ, which was independently confirmed by measuring V(D)J recombination. Furthermore, depletion of FA proteins resulted in reduced HR protein foci and increased NHEJ protein recruitment to replication-associated DSBs, consistent with our observation that the use of canonical NHEJ increases after depletion of FA proteins in cycling cells. FA-depleted cells and FA-mutant cells were exquisitely sensitive to a DNA-PKcs inhibitor (DNA-PKi) after sustaining replication-associated double strand breaks (DSBs). By contrast, after DNA interstrand crosslinks, DNA-PKi resulted in increased survival in FA-deficient cells, implying that NHEJ is contributing to lethality after crosslink repair. Our results suggest FA proteins inhibit NHEJ, since repair intermediates from crosslinks are rendered lethal by NHEJ. The implication is that bone marrow failure in FA could be triggered by naturally occurring DNA crosslinks, and DNA-PK inhibitors would be protective. Since some sporadic cancers have been shown to have deficiencies in the FA-pathway, these tumors should be vulnerable to NHEJ inhibitors with replication stress, but not with crosslinking agents, which could be tested in future clinical trials.

Epithelial to mesenchymal transition inducing transcription factors and metastatic cancer

The epithelial to mesenchymal transition (EMT) is an important step for the developmental process. Recent evidences support that EMT allows the tumor cells to acquire invasive properties and to develop metastatic growth characteristics. Some of the transcription factors, which are actively involved in EMT process, have a significant role in the EMT-metastasis linkage. A number of studies have reported that EMT-inducing transcription factors (EMT-TFs), such as Twist, Snail, Slug, and Zeb, are directly or indirectly involved in cancer cell metastasis through a different signaling cascades, including the Akt, signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase (MAPK) and Wnt pathways, with the ultimate consequence of the downregulation of E-cadherin and upregulation of metastatic proteins, such as N-cadherin, vimentin, matrix metalloproteinase (MMP)-2, etc. This review summarizes the update information on the association of EMT-TFs with cancer metastasis and the possible cancer therapeutics via targeting the EMT-TFs.

Epigenetic alterations in endocrine-related cancer

Aberrant epigenetics is a hallmark of cancer, and endocrine-related tumors are no exception. Recent research has been identifying an ever-growing number of epigenetic alterations in both genomic DNA methylation and histone post-translational modification in tumors of the endocrine system. Novel microarray and ultra-deep sequencing technologies have allowed the identification of genome-wide epigenetic patterns in some tumor types such as adrenocortical, parathyroid, and breast carcinomas. However, in other cancer types, such as the multiple endocrine neoplasia syndromes and thyroid cancer, tumor information is limited to candidate genes alone. Future research should fill this gap and deepen our understanding of the functional role of these alterations in cancer, as well as defining their possible clinical uses.

HER2 and GATA4 are new prognostic factors for early-stage ovarian granulosa cell tumor-a long-term follow-up study

Granulosa cell tumors (GCTs) carry a risk of recurrence also at an early stage, but reliable prognostic factors are lacking. We assessed clinicopathological prognostic factors and the prognostic roles of the human epidermal growth factor receptors (HER 2–4) and the transcription factor GATA4 in GCTs. We conducted a long-term follow-up study of 80 GCT patients with a mean follow-up time of 16.8 years. A tumor-tissue microarray was immunohistochemically stained for HER2–4 and GATA4. Expression of HER2–4 mRNA was studied by means of real time polymerase chain reaction and HER2 gene amplification was analyzed by means of silver in situ hybridization. The results were correlated to clinical data on recurrences and survival. We found that GCTs have an indolent prognosis, with 5-year disease-specific survival (DSS) being 97.5%. Tumor recurrence was detected in 24% of the patients at a median of 7.0 years (range 2.6–18 years) after diagnosis. Tumor stage was not prognostic of disease-free survival (DFS). Of the molecular prognostic factors, high-level expression of HER2, and GATA4, and high nuclear atypia were prognostic of shorter DFS. In multivariate analyses, high-level coexpression of HER2 and GATA4 independently predicted DFS (hazard ratio [HR] 8.75, 95% CI 2.20–39.48, P = 0.002). High-level expression of GATA4 also predicted shorter DSS (HR 3.96, 95% CI 1.45–12.57, P = 0.006). In multivariate analyses, however, tumor stage (II–III) and nuclear atypia were independent prognostic factors of DSS. In conclusion HER2 and GATA4 are new molecular prognostic markers of GCT recurrence, which could be utilized to optimize the management and follow-up of patients with early-stage GCTs.

BRCA1 promoter hypermethylation and protein expression in ovarian carcinoma--an Indian study

Mounting evidences suggest that aberrant methylation of CpG islands is a major pathway leading to the inactivation of tumour suppressor genes and the development of cancer. The aim of the current study was to examine the prevalence of the promoter hypermethylation and protein expression of the BRCA1 gene in epithelial ovarian carcinoma (EOC) to understand the role of epigenetic silencing in ovarian carcinogenesis. We studied the promoter methylation of the BRCA1 gene by methylation-specific PCR in a cohort of 88 patients with EOC, 14 low malignant potential (LMP) tumours and 20 patients with benign tumours of the ovary. The expression of the BRCA1 protein by immunohistochemical analysis was carried out in a subset of 64 EOCs, 10 LMP tumours, 10 benign tumours and 5 normal ovarian tissues. The frequencies of methylation in EOCs and LMP tumours were 51.2 and 57%, respectively, significantly higher (p = 0.000 and p = 0.001) in comparison to benign tumours and normal ovarian tissue where no methylation was seen. Expression of BRCA1 was significantly lower in EOCs (p = 0.003). Lack of protein expression correlated with tumour grade and type. The methylation status correlated well with downregulation of BRCA1 expression. Our results clearly demonstrate that hypermethylation of BRCA1 promoter is a frequent event in ovarian cancer. These data support the hypothesis that BRCA1 promoter methylation plays an important role in the functional inactivation of BRCA1. Follow-up clinical data will reveal the impact of BRCA1 methylation on survival.

Twist: a molecular target in cancer therapeutics

Twist, the basic helix-loop-helix transcription factor, is involved in the process of epithelial to mesenchymal transitions (EMTs), which play an essential role in cancer metastasis. Overexpression of Twist or its promoter methylation is a common scenario in metastatic carcinomas. Twist is activated by a variety of signal transduction pathways, including Akt, signal transducer and activator of transcription 3, mitogen-activated protein kinase, Ras, and Wnt signaling. Activated Twist upregulates N-cadherin and downregulates E-cadherin, which are the hallmarks of EMT. Moreover, Twist plays an important role in some physiological processes involved in metastasis, like angiogenesis, invadopodia, extravasation, and chromosomal instability. Twist also protects cancer cells from apoptotic cell death. In addition, Twist is responsible for the stemness of cancer cells and the generation of drug resistance. Recently, targeting Twist has gained significant interests in cancer therapeutics. The inactivation of Twist by small RNA technology or chemotherapeutic approach has been proved successful. Moreover, several inhibitors which are antagonistic to the upstream or downstream molecules of Twist signaling pathways have also been identified. Development of potential treatment strategies by targeting Twist has a great promise in cancer therapeutics.

Detection of novel biomarkers for ovarian cancer with an optical nanotechnology detection system enabling label-free diagnostics

Ovarian carcinoma has the highest lethality rate of gynecologic tumors, largely attributed to the late-stage diagnosis of the disease. Reliable tools for both accurate diagnosis and early detection of disease onset are lacking, and presently less than 20% of ovarian cancers are detected at an early stage. Protein biomarkers that allow the discrimination of early and late stages of ovarian serous carcinomas are urgently needed as they would enable monitoring pre-symptomatic aspects of the disease, disease progression, and the efficacy of intervention therapies. We compare the absolute and relative protein levels of six protein biomarkers for ovarian cancer in five different established ovarian cancer cell lines, utilizing both quantitative immunoblot analysis and a guided-mode resonance (GMR) bioassay detection system that utilizes a label-free optical biosensor readout. The GMR sensor approach provided highly accurate, consistent, and reproducible quantification of protein biomarkers as validated by quantitative immunoblotting, as well as enhanced sensitivity, and is therefore suitable for quantification and detection of novel biomarkers for ovarian cancer. We identified fibronectin, apolipoprotein A1, and TIMP3 as potential protein biomarkers for the differential diagnosis of primary versus metastatic ovarian carcinoma. Future studies are needed to confirm the suitability of protein biomarkers tested herein in patient samples.

CpG island methylation of TMS1/ASC and CASP8 genes in cervical cancer

BACKGROUND

Gene silencing associated with aberrant methylation of promoter region CpG islands is an acquired epigenetic alteration that serves as an alternative to genetic defects in the inactivation of tumor suppressor and other genes in human cancers.

AIMS

This study describes the methylation status of TMS1/ASC and CASP8 genes in cervical cancer. We also examined the prevalence of TMS1/ASC and CASP8 genes methylation in cervical cancer tissue and none--neo plastic samples in an effort to correlate with smoking habit and clinicopathological features.

METHOD

Target DNA was modified by sodium bisulfite, converting all unmethylated, but not methylated, cytosines to uracil, and subsequently amplified by Methylation Specific (MS) PCR with primers specific for methylated versus unmethylated DNA. The PCR product was detected by gel electrophoresis and combined with the clinical records of patients.

RESULTS

The methylation pattern of the TMS1/ASC and CASP8 genes in specimens of cervical cancer and adjacent normal tissues were detected (5/80 (6.2%), 3/80 (3.75%)-2/80 (2.5%), 1/80 (1.2%) respectively). No statistical differences were seen in the extent of differentiation, invasion, pathological type and smoking habit between the methylated and unmethylated tissues (P > 0.05).

CONCLUSION

The present study conclude that the frequency of TMS1/ASC and CASP8 genes methylation in cervical cancer are rare (< 6%), and have no any critical role in development of cervical cancer.

Specific 50'CpG island methylation signatures of FHIT and p16 genes and their potential diagnostic relevance in Indian breast cancer patients

Even after tremendous molecular studies, early detection,more accurate and sensitive diagnosis, and prognosis of breast cancer appear to be a riddle so far. To stab the enigma, this study is designed to envisage DNA methylation signatures as cancer-specific and stage-specific biomarkers in Indian patients. Rigorous review of scattered scientific reports on aberrant DNA methylation helped us to select and analyze a potential tumor suppressor gene pair (FHIT and p16 genes) in breast cancer patients. Methylation signatures from 232 primary sporadic breast cancer patients were pinpointed by methylation-specific PCR (MSP). To increase the sensitivity, we combined both MSP and expression studies (RT-PCR and Northern blotting) in a reproducible manner. Statistical analysis illustrated that hypermethylation of FHIT gene ( p < 0.0001) and p16 gene ( p=0.04) may be used as a potential diagnostic marker to diagnose the early and locally advanced stages of breast cancer. Additionally, the study authenticates the dependency of methylation and expressional loss of p16 gene on FHIT gene silencing. This observation not only describes the severity of disease when both genes are silenced but also drives to speculate the molecular cross talk between two genes or genetic pathways dictated by them separately.

Epigenetic Inactivation of IκB Kinase-α in Oral Carcinomas and Tumor Progression

PURPOSE

The loss of epithelial phenotypes in the process of carcinoma progression correlates with clinical outcome, and genetic/epigenetic changes accumulate aggressive clones toward uncurable disease. IkappaB kinase-alpha (IKKalpha) has a decisive role in the development of the skin and establishes keratinocyte phenotypes. We assessed clinical implications of IKKalpha expression in oral carcinomas and epigenetic aberrations for the loss of expression.

EXPERIMENTAL DESIGN

We examined IKKalpha expression in oral carcinomas by immunostaining (n = 64) and genetic instability by microsatellite PCR (n = 46). Promoter methylation status was analyzed by bisulfite-modified sequence (n = 11).

RESULTS

IKKalpha was expressed in the nucleus of basal cells of normal oral epithelium, but not or marginally detected in 32.8% of carcinomas. The immunoreactivity was significantly decreased in less differentiated carcinomas (P < 0.05) and correlated to long-term survival of patients (P < 0.01) with an independent prognostic value (P < 0.05). Although allelic/biallelic loss of the gene was limited to four cases, we detected microsatellite instability in 63.0% cases in which the immunoreactivities were decreased and the promoter was hypermethylated.

CONCLUSION

These results showed that oral carcinomas exhibiting genetic instability and promoter hypermethylation down-regulate expression of IKK and suggest that the epigenetic loss of the expression closely associates with disease progression toward unfavorable prognosis.

Methylation mediated silencing of TMS1/ASC gene in prostate cancer

BACKGROUND

Transcriptional silencing associated with aberrant promoter methylation has been established as an alternate pathway for the development of cancer by inactivating tumor suppressor genes. TMS1 (Target of Methylation induced Silencing), also known as ASC (Apoptosis Speck like protein containing a CARD) is a tumor suppressor gene which encodes for a CARD (caspase recruitment domain) containing regulatory protein and has been shown to promote apoptosis directly and by activation of downstream caspases. This study describes the methylation induced silencing of TMS1/ASC gene in prostate cancer cell lines. We also examined the prevalence of TMS1/ASC gene methylation in prostate cancer tissue samples in an effort to correlate race and clinico-pathological features with TMS1/ASC gene methylation.

RESULTS

Loss of TMS1/ASC gene expression associated with complete methylation of the promoter region was observed in LNCaP cells. Gene expression was restored by a demethylating agent, 5-aza-2'deoxycytidine, but not by a histone deacetylase inhibitor, Trichostatin A. Chromatin Immunoprecipitation (ChIP) assay showed enrichment of MBD3 (methyl binding domain protein 3) to a higher degree than commonly associated MBDs and MeCP2. We evaluated the methylation pattern in 66 prostate cancer and 34 benign prostatic hyperplasia tissue samples. TMS1/ASC gene methylation was more prevalent in prostate cancer cases than controls in White patients (OR 7.6, p 0.002) while no difference between the cases and controls was seen in Black patients (OR 1.1, p 0.91).

CONCLUSION

Our study demonstrates that methylation-mediated silencing of TMS1/ASC is a frequent event in prostate cancer, thus identifying a new potential diagnostic and prognostic marker for the treatment of the disease. Racial differences in TMS1/ASC methylation patterns implicate the probable role of molecular markers in determining in susceptibility to prostate cancer in different ethnic groups.

Recent Advances in the Pathology and Classification of Ovarian Sex Cord-Stromal Tumors

In recent years, our knowledge of ovarian sex cord-stromal tumors has increased, and their classification has evolved. In this review, recent advances in the classification and pathology of ovarian sex cord-stromal tumors are discussed, and the controversy regarding the classification of sex cord tumor with annular tubules is addressed. The current classification is built on those of the past, and future classifications should improve on what is now in place incorporating new knowledge from more sophisticated clinicopathologic studies and advanced molecular techniques. This review emphasizes articles written in the 21st century as well as those that have significantly advanced our knowledge of sex cord-stromal tumors in past decades. The tumors in this group occur over a wide age range and are often unilateral. In difficult cases, immunocytochemistry provides improved diagnostic accuracy. The most useful immunohistochemical marker for their identification is alpha-inhibin, which is positive in most neoplasms in the sex cord-stromal group. The article concludes with a section discussing the pathogenesis of sex cord-stromal tumors.

Methylation and messenger RNA expression of p15INK4b but not p16INK4a are independent risk factors for ovarian cancer

PURPOSE

The purpose of this research was to compare methylation status and mRNA expression of p15INK4b and p16INK4a in serous epithelial ovarian cancer tissues and normal ovarian tissues.

EXPERIMENTAL DESIGN

We analyzed the DNA methylation status and mRNA expression of p15INK4b and p16INK4a in 52 ovarian cancer specimens and 40 normal ovarian specimens by using methylation-specific PCR and real-time reverse transcription-PCR, respectively.

RESULTS

Although the p15INK4b and p16INK4a mRNA expression levels were highly correlated with each other (P < 0.001), the methylation status did not seem to be linked with levels of mRNA expression, as no association between the two events was found for either gene. Promoter hypermethylation of p15(INK4b) was more common in ovarian cancer (30.8% for the 52 cases) than in normal ovaries (5% for the 40 controls without ovarian cancer; P = 0.005) but not methylation of p16INK4a (25% for cancer versus 37.5% for normal; P = 0.288). The relative mRNA expression levels of p15INK4b were significantly lower in ovarian cancer (12.9%) than in normal ovaries (41.7%; P = 0.008) but not those of p16INK4a (27% for cases versus 32.8% for controls; P = 0.754). Only high methylation rate and low mRNA expression of p15INK4b were independent risk factors for ovarian cancer (adjusted odds ratio, 5.67; 95% confidence interval, 0.85-37.9 for high methylation rate and odds ratio, 8.98; 95% confidence interval, 1.58-50.9 for low mRNA expression, respectively).

CONCLUSIONS

Our results suggest that epigenetic alterations in p15INK4b but not p16INK4a have an important role in ovarian carcinogenesis and that mechanisms other than methylation may exist to reduce gene expression of p15INK4b in ovarian cancer.

Methylation of the Tumor Suppressor Gene RASSF1A in Human Tumors

Loss of heterozygosity of a segment at 3p21.3 is frequently observed in lung cancer and several other carcinomas. We have identified the Ras-association domain family 1A gene (RASSF1A), which is localized at 3p21.3 in a minimum deletion sequence. De novo methylation of the RASSF1A promoter is one of the most frequent epigenetic inactivation events detected in human cancer and leads to silencing of RASSF1A expression. Hypermethylation of RASSF1A was frequently found in most major types of human tumors including lung, breast, prostate, pancreas, kidney, liver, cervical, thyroid and many other cancers. The detection of RASSF1A methylation in body fluids such as serum, urine, and sputum promises to be a useful marker for early cancer detection. The functional analysis of RASSF1A reveals a potential involvement of this protein in apoptotic signaling, microtubule stabilization, and cell cycle progression.

CpG methylation of the FHIT, FANCF, cyclin-D2, BRCA2 and RUNX3 genes in Granulosa cell tumors (GCTs) of ovarian origin

Background

Granulosa cell tumors (GCTs) are relatively rare and are subtypes of the sex-cord stromal neoplasms. Methylation induced silencing in the promoters of genes such as tumor suppressor genes, DNA repair genes and pro-apoptotic genes is recognised as a critical factor in cancer development.

Methods

We examined the role of promoter hypermethylation, an epigenetic alteration that is associated with the silencing tumor suppressor genes in human cancer, by studying 5 gene promoters in 25 GCTs cases by methylation specific PCR and RT-PCR. In addition, the compatible tissues (normal tissues distant from lesion) from three non-astrocytoma patients were also included as the control.

Results

Frequencies of methylation in GCTs were 7/25 (28 % for FHIT), 6/25 (24% for FNACF), 3/25 (12% for Cyclin D2), 1/25 (4% for BRCA2) and 14/25 (56%) in RUNX3 genes. Correlation of promoter methylation with clinical characteristics and other genetic changes revealed that overall promoter methylation was higher in more advanced stage of the disease. Promoter methylation was associated with gene silencing in GCT cell lines. Treatment with methylation or histone deacetylation-inhibiting agents resulted in profound reactivation of gene expression.

Conclusions

These results may have implications in better understanding the underlying epigenetic mechanisms in GCT development, provide prognostic indicators, and identify important gene targets for treatment.