Methylation-specific High Resolution Melting Research Articles

Quantitative DNA Methylation Analysis and Epigenotype-Phenotype Correlations in Taiwanese Patients with Silver-Russell Syndrome.

Background: Silver-Russell syndrome (SRS; OMIM #180860) is a clinically and genetically heterogeneous imprinting disorder characterized by prenatal and postnatal growth failure. The aim of this study was to identify the epigenotype-phenotype correlations in these patients using quantitative DNA methylation analysis. Methods: One hundred and eighty-three subjects clinically suspected of having SRS were referred for diagnostic testing by the methylation profiling of H19-associated imprinting center (IC) 1 and imprinted PEG1/MEST regions using methylation-specific high-resolution melting analysis and methylation quantification with the MassARRAY assay. Correlations between quantitative DNA methylation status and clinical manifestations of the subjects according to the Netchine-Harbison (N-H) clinical scoring system for SRS were analyzed. Results: Among the 183 subjects, 90 had a clinical diagnosis of SRS [N-H score ≥ 4 (maximum = 6)] and 93 had an SRS score < 4. Molecular lesions were detected in 41% (37/90) of the subjects with a clinical diagnosis of SRS, compared with 3% (3/93) of those with an N-H score < 4. The IC1 methylation level was negatively correlated with the N-H score. The molecular diagnosis rate was positively correlated with the N-H score. Thirty-one subjects had IC1 hypomethylation (IC1 methylation level <35% by the MassARRAY assay), seven had maternal uniparental disomy 7, and two had pathogenic copy number variants. Among the 90 subjects with an N-H score ≥ 4, the IC1 methylation level was significantly different between those with or without some clinical SRS features, including birth length ≤ 10th centile, relative macrocephaly at birth, normal cognitive development, body asymmetry, clinodactyly of the fifth finger, and genital abnormalities. Conclusions: This study confirmed the suitability of the N-H clinical scoring system as clinical diagnostic criteria for SRS. Quantitative DNA methylation analysis using the MassARRAY assay can improve the detection of epigenotype-phenotype correlations, further promoting better genetic counseling and multidisciplinary management for these patients.

EVALUATION OF SECRETED FRIZZLED-RELATED PROTEIN-2 METHYLATION STATUS IN PATIENTS WITH CHRONIC MYELOID LEUKEMIA

BackgroundChronic Myeloid Leukemia (CML) is a myeloproliferative disorder defined by the chromosomal translocation (t) (9;22) encoding for the BCR-ABL fusion gene. Tumor development and progression may be affected by hypermethylation of promoter regions of certain genes. Secreted Frizzled-Related Proteins (SFRPs) genes produce Wnt signaling antagonists, and their epigenetic silencing has been detected in multiple types of leukaemia. While epigenetic silencing has been broadly reported for SFRPs, SFRP2 is a family member less studied in leukaemia.&#x0D; ObjectivesTo evaluate SFRP2 gene methylation patterns in CML patients compared with healthy individuals.&#x0D; Materials and MethodsSodium bisulfite was applied to the extracted DNA from blood samples of 75 CML patients and 25 healthy subjects who served as the control group. The DNA was then analyzed by methylation-specific high-resolution melting (MS-HRM) using specific primers for the SFRP2 gene in promoter sequence.&#x0D; ResultsForty-five out of 75 CML patients investigated were shown to have SFRP2 methylation percentages between 50% to 100%, whereas 19 out of 25 healthy subjects had a methylation level of less than 50%.&#x0D; ConclusionThe current study demonstrated that SFRP2 promoter hypermethylation exists in CML, as in several other solid tumours. Hence, methylation of this gene may play a part in initiating leukemogenesis.

P14.01.A LIQUID BIOPSY OF GLIOMA-RELATED GENES USING A NOVEL AMPLIFICATION TECHNIQUE

Abstract BACKGROUND In the pathological classification of brain tumors, newly revised in 2021, molecular genetic analysis of gliomas has become more important for diagnosis and understanding of the pathogenesis of gliomas. Gliomas are prone to recurrence and malignant progression, and collecting tumor tissue during every genetic analysis is highly invasive. Therefore, techniques have been developed to analyze tumor-derived circulating cell-free DNA (ccfDNA) in the cerebrospinal fluid as a substitute for tissue collection. However, the amount of ccfDNA derived from the cerebrospinal fluid is extremely small and the number of cases for whom genetic analysis is possible is currently limited. In this study, we attempted to establish a novel method for the integrated analysis of glioma-related genes by in vitro amplification of cerebrospinal fluid-derived ccfDNA from glioma patients and a highly sensitive assay. Methods : Tumor-derived ccfDNA was extracted and purified from 1 ml of cerebrospinal fluid obtained by lumbar puncture using the Maxwell RSC instrument in five glioma cases. Hot spots of mutations in IDH1 and H3F3A genes were analyzed by high resolution melting (HRM), TERT mutation by droplet digital PCR, MGMT promoter methylation by methylation-specific HRM, and chromosome 1p/19q loss by multiplex ligation-dependent probe amplification. For samples in which the amount of ccfDNA was too small to analyze, DNA was amplified approximately 500-fold by DNA polymerase using the GenomiPhi kit and analyzed by the same assay method. Results and CONCLUSION s : Although two of the five cases required amplification with the GenomiPhi kit, it was possible to analyze all cases for glioma-related genes as described above. Although the amount of ccfDNA obtained from low-grade gliomas and gliomas that are not in contact with the ventricles or subarachnoid space is small, this amplification method may increase the possibility of liquid biopsy using cerebrospinal fluid in gliomas.

Methylomic biomarkers of lithium response in bipolar disorder: a clinical utility study

BackgroundResponse to lithium (Li) is highly variable in bipolar disorders (BD). Despite decades of research, no clinical predictor(s) of response to Li prophylaxis have been consistently identified. Recently, we developed epigenetic Methylation Specific High-Resolution Melting (MS-HRM) assays able to discriminate good responders (GR) from non-responders (NR) to Li in individuals with BD type 1 (BD-I). This study examined whether a combination of clinical and epigenetic markers can distinguish NR from other types of Li responders.MethodsWe recorded clinical variables that are potentially associated with Li response in 64 individuals with BD-I. MS-HRM assays were performed on DNA isolated from peripheral blood. We used backward stepwise logistic regression analyses, followed by receiver operating characteristic (ROC) curve analysis to estimate the performance of the clinical variables, alone then in combination with the epigenetic biomarkers, to identify GR and partial responders (PaR) vs NR.ResultsPolarity at onset, psychotic symptoms at onset and family history of BD classified correctly 70% of individuals according to their Li response (PaR + GR = 86%; NR = 35%). When combined with the epigenetic biomarkers, these three clinical variables plus alcohol misuse (and one DMR: Differentially Methylated Region) correctly classified 86% of individuals, improving the prediction of PaR + GR (93%) and of NR (70%). The ROC analysis demonstrated an improvement in the area under the curve from 0.75 (clinical variables alone) to 0.87 (combination of clinical and epigenetic markers).ConclusionsCombining clinical predictors and DNA methylation markers of Li response may have greater utility in clinical practice than relying on clinical characteristics alone.

BIOM-30. ANALYSIS OF GLIOMA-RELATED GENES USING A BREAKTHROUGH AMPLIFICATION TECHNIQUE FOR CELL-FREE DNA IN CEREBROSPINAL FLUID

Abstract BACKGROUND In the pathological classification of brain tumors, newly revised in 2021, molecular genetic analysis of gliomas has become more important for diagnosis and understanding of the pathogenesis of the disease. Gliomas are prone to recurrence and malignant progression, and collecting tumor tissue during every genetic analysis is highly invasive. Therefore, techniques have been developed to analyze tumor-derived circulating cell-free DNA (ccfDNA) in the cerebrospinal fluid as a substitute for tissue collection. However, the amount of ccfDNA derived from the cerebrospinal fluid is extremely small and the number of cases for whom genetic analysis is possible is currently limited. In this study, we attempted to establish an efficient method for the integrated analysis of glioma-related genes by in vitro amplification of cerebrospinal fluid-derived ccfDNA from glioma patients and a highly sensitive assay. METHODS Tumor-derived ccfDNA was extracted and purified from 1 ml of cerebrospinal fluid obtained by lumbar puncture using the Maxwell RSC instrument in five glioma cases. Hot spots of mutations in IDH1 and H3F3A genes were analyzed by high resolution melting (HRM), TERT mutation by droplet digital PCR, MGMT promoter methylation by methylation-specific HRM, and chromosome 1p/19q loss by multiplex ligation-dependent probe amplification. For samples in which the amount of ccfDNA was too small to analyze, DNA was amplified approximately 500-fold by DNA polymerase using the GenomiPhi kit and analyzed by the same assay method. RESULTS AND CONCLUSIONS Although two of the five cases required amplification with the GenomiPhi kit, it was possible to analyze all cases for glioma-related genes as described above. Although the amount of ccfDNA obtained from low-grade gliomas and gliomas that are not in contact with the ventricles or subarachnoid space is small, this amplification method may increase the possibility of liquid biopsy using cerebrospinal fluid.

Methylation of FBN1, SPG20, ITF2, RUNX3, SNCA, MLH1, and SEPT9 genes in circulating cell-free DNA as biomarkers of colorectal cancer.

Investigating aberrant tumor-specific methylation in plasma cell-free DNA provides a promising and noninvasive biomarker for cancer detection. We aimed to investigate methylation status of some promoter regions in the plasma and tumor tissues to find biomarkers for early detection of colorectal cancer. This case-control study on seventy colorectal cancer patients and fifty matched healthy controls used Methylation-Specific High-Resolution Melting Curve analysis to evaluate the methylation of the selected promoter regions in converted genomic tissue DNA and plasma cfDNA. The methylation levels in selected regions of SPG20 (+24375 to +24680, +24209 to +24399, and +23625 to +23883), SNCA (+807 to +1013, +7 to +162, and -180 to +7), FBN1 (+223 to +429, +1 to +245, and -18 to -175), ITF2 (+296 to +436 and -180 to +55), SEPT9 (-914412 to -91590 and -99083 to -92264), and MLH1 (-13 to +22) were significantly higher in tumor tissues compared with normal adjacent tissues. The methylation levels of FBN1, ITF2, SNCA, and SPG20 promoters were significantly higher in the patient's plasma compared to patient's normal tissue and plasma of healthy control subjects. FBN1, SPG20, and SEPT9 promoter methylation had a good diagnostic performance for discriminating CRC tissues from normal adjacent tissues (AUC > 0.8). A panel of SPG20, FBN1, and SEPT9 methylation had a higher diagnostic value than that of any single biomarker and other panels in tissue-based assay (AUC > 0.9). The methylation of FBN1(a) and SPG20(a) regions, as the closest region to the first coding sequence (CDS), had a good diagnostic performance in plasma cfDNA (AUC > 0.8) while a panel consisted of FBN1(a) and SPG20(a) regions showed excellent diagnostic performance for CRC detection in plasma cfDNA (AUC > 0.9). Methylation of FBN1(a) and SPG20(a) promoter regions in the plasma cfDNA can be an excellent simple, non-invasive blood-based test for early detection of CRC.

The correlation between promoter hypermethylation of VDR, CLDN, and CasR genes and recurrent stone formation

ObjectivesRecurrent Kidney stone formation is a main medical problem imposing a significant burden on both healthcare and the economy worldwide. Environmental and genetic factors have been linked to a bigger risk of kidney stone formation. We aim to assess the role of methylation on recurrent stone formation in three target genes.MethodsWe aimed to check the association between promoter hypermethylation vitamin D receptor (VDR), calcium-sensing receptor (CaSR), and claudin 14 (CLDN14) genes in recurrent kidney stones. We enrolled 30 consecutive recurrent kidney stone formers (age 18–60 years) (cases) and 30 age and gender-matched controls.3. To identify promoter methylation, two target regions from each candidate gene were bisulfited after blood collection and DNA extraction. Methylation quantification was done through methylation-specific high resolution melting (MS-HRM).ResultsThe mean age of the patients and controls (mean ± SD) was 49.58 ± 14.23 years and BMI 36.12 ± 2.72. The methylation status in all six target regions was meaningfully different between the stone-former group and controls when methylation was considered in three clusters of unmethylated, methylated, and hypermethylated. A higher effect in VDR and CLDN was observed compare to CasR (p-value < 0.001, and < 0.005 versus p-value < 0.256).ConclusionsMethylation as an important epigenetic mechanism should be considered more in recurrent stone formations. Promoter hypermethylation of VRD and CLDN genes may have an essential role in recurrent kidney stones formations.

Evaluation of Sirtuin1 promoter DNA methylation in peripheral blood monocytes of patients with coronary artery disease

BackgroundCoronary artery disease (CAD) is one of the major causes of mortality worldwide. The Sirt1 gene, a histone deacetylase, is a significant element in CAD by playing anti-aging, antioxidant and anti-inflammatory roles. One of the regulators of Sirt1 gene expression is DNA methylation which is the most important epigenetics regulators in CAD. The aim of the present study was the methylation status assessment of Sirt1 promoter in CAD patients in Kerman, southeastern Iran. MethodsIn this study, 61 individuals as patient group and 29 individuals as control group were participated. The DNA was extracted from isolated monocytes. Then, DNA methylation level was investigated by the methylation specific high resolution melting (MS-HRM) technique and the significance level was analyzed by t-test. ResultsThe results showed that both groups were rarely methylated. Indeed, a wide range of individuals showed approximately 25% methylation level. Our data indicates that there was no relation between Sirt1 promoter methylation level and CAD (P-Value = 0.664). ConclusionAccording to our results, methylation of this gene did not appear to be correlated with CAD, so the methylation status of Sirt1 does not seem to be an informative biomarker for CAD patients. Better characterization of related genes in CAD cases such as Sirt1 can help to proper treatment strategies.

Methylomic Biomarkers of Lithium Response in Bipolar Disorder: A Proof of Transferability Study.

Response to lithium (Li) is highly variable in bipolar disorders (BD) and no clinical or biological predictors of long-term response have been validated to date. Using a genome-wide methylomic approach (SeqCapEpi), we previously identified seven differentially methylated regions (DMRs) that discriminated good from non-responders (prophylactic response phenotype defined using the “Alda” scale). This study is a proof of transferability from bench to bedside of this epigenetic signature. For this purpose, we used Methylation Specific High-Resolution Melting (MS-HRM), a PCR based method that can be implemented in any medical laboratory at low cost and with minimal equipment. In 23 individuals with BD, MS-HRM measures of three out of seven DMRs were technically feasible and consistencies between SeqCapEpi and MS-HRM-measures were moderate to high. In an extended sample of individuals with BD (n = 70), the three MS-HRM-measured DMRs mainly predicted nonresponse, with AUC between 0.70–0.80 according to different definitions of the phenotype (Alda- or machine-learning-based definitions). Classification tree analyses further suggested that the MS-HRM-measured DMRs correctly classified up to 84% of individuals as good or non-responders. This study suggested that epigenetic biomarkers, identified in a retrospective sample, accurately discriminate non-responders from responders to Li and may be transferrable to routine practice.

DNA hypermethylation of CADM1, PAX5, WT1, RARβ, and PAX6 genes in oropharyngeal cancer associated with human papillomavirus

ABSTRACT Recently, an increasing incidence of HPV-induced oropharyngeal squamous cell carcinoma (OPSCC) has been observed. Moreover, locoregionally advanced stages require a combined modal approach, and the prognosis is poor. Therefore, it is essential to find early diagnostic and prognostic biomarkers. DNA methylation changes play a crucial role in the process of carcinogenesis and are often investigated as promising biomarkers in many types of cancer. For analysis of DNA methylation levels of selected tumour suppressor genes in HPV-positive and HPV-negative samples (including primary tumours and corresponding metastases of metastasizing OPSCCs, primary tumours of non-metastasizing OPSCCs, and control samples), methylation-specific MLPA and methylation-specific high-resolution melting analyses were used. A significant difference in methylation between OPSCCs and the control group was observed in WT1, PAX6 (P < 0.01) and CADM1, RARβ (P < 0.05) genes. CADM1 and WT1 hypermethylation was detected mostly in HPV-positive samples; all but one HPV-negative samples were unmethylated. Moreover, hypermethylation of PAX5 gene was observed in metastases compared with control samples and was also associated with shorter overall survival of all patients (P < 0.05). Associations described herein between promoter methylation of selected genes and clinicopathological data could benefit OPSCC patients in the future by improvement in screening, early detection, and prognosis of the disease.

Improved microsatellite instability detection in colorectal cancer patients by a combination of fourteen markers especially DNMT3a, DCD, and MT1X.

Microsatellite instability (MSI) results from genetic and epigenetic changes. Studying Microsatellite instability can help in treatment and categorization of colorectal cancer (CRC) patients. We aimed to investigate whether 14 genomic markers consisting of BAT-62, BAT-60, BAT-59a, BAT-56a, BAT-56b, DCD, RIOX, RNF, FOXP, ACVR, CASP2, HSP110, MT1X, and DNMT3a can increase the detection rate of MSI in CRC. Samples were stratified by pentaplex panel (Promega) and 14 markers using multiplex PCR and fragment analysis. In MSI+ samples, to identify the pattern of BRAF V600E mutation and MLH1 promoter methylation, ARMS-scorpion, and Methylation-Specific High-Resolution Melting Curve analysis, were applied respectively. Totally, 35 MSI+ cases identified by 14 marker panel. Only 18 cases of them were detected by both panels which are pentaplex and 14 marker. On the other hand, 17 new MSI+ cases just were identified by 14 markers panel. The highest diagnostic value among 14 markers is related to three makers, namely DCD, MT1X, and DNMT3a. In MSI+ cases, the rate of MLH1 promoter methylation was insignificant, (P value = 0.3979) while the rate of observed BRAFV600E mutation was significantly higher (P value = 0.0002). Fourteen marker panel showed higher sensitivity in comparison with the pentaplex panel increasing the detection rate of MSI+ cases up to 1.94 fold. Three markers namely DNMT3a, DCD, and MT1X of 14 marker panel were the best among them showing excellent diagnostic value. A combination of these markers showed 100% sensitivity and specificity in the studied group. In contrary to the markers in the pentaplex panel, these markers had the ability to detect MSI without any bias for the clinicopathological features. These markers will help to identify more end-stage MSI+ tumors which are located distal colon.

Evaluation of Methylation at Promoter Regions of Long Non-coding RNAs in Patients with Acute Lymphoblastic Leukemia

Introduction Acute lymphoblastic leukemia (ALL) is a fetal hematologic disorder that is mostly observed in children. Both B and T lymphocytes have been reported to play a role in ALL etiology. Long non-coding RNAs (lncRNAs) are large regulatory molecules with more than 200 nucleotides that participate in various cellular processes. Methylation at the promoter regions of these regulatory molecules has been reported to vary between ALL patients and healthy controls. This study aimed to evaluate methylation status at promoter regions of lncRNAs between these two groups. Methods In the current study, 80 ALL patients and 80 healthy controls were enrolled. The intravenous blood samples were obtained from all patients and controls. The extracted DNA from blood samples underwent sodium bisulfite treatment. Thereafter, methylation levels in the promoter regions of lncRNAs RP11-137H2.4, RP11-624c23.1, RP11-203E8, RP11-446E9, and RP11-68118.10 were evaluated using methylation specific‑high resolution melting (MS‑HRM). Moreover, the receiver operating characteristic curve (ROC) analysis was performed to examine the sensitivity and specificity of the tests. Results The methylation levels of all studied lncRNAs including RP11-137H2.4 (P =0.001837), RP11-624c23.1 (P = 0.000003), RP11-203E8 (P = 0.000092), RP11-446E9 (P = 0.02447), and RP11-68118.10 (P =0.000086) were significantly increased. ROC curve analysis also showed that all lncRNAs could be used as diagnostic markers. Conclusion This study showed that methylation alterations of lncRNAs could be considered as novel biomarkers for early detection of ALL. Furthermore, owing to the possible role of studied lncRNAs as tumor suppressors, they could be reliable treatment targets for methylation modifications. Further research is still required to elucidate the role of these lncRNAs in ALL etiology.

PAX2 promoter methylation and AIB1 overexpression promote tamoxifen resistance in breast carcinoma patients.

Disease recurrence is an important obstacle in estrogen receptor positive (ER+) tamoxifen treated breast carcinoma patients. Tamoxifen resistance-related molecular mechanisms are not fully understood. Alteration in DNA methylation which contributes to transcriptional regulation of cancer-related genes plays a crucial role in tamoxifen response. In the present study, the contribution of promoter methylation and mRNA expression of PAX2 and AIB1 in the development of breast carcinoma and tamoxifen refractory was assessed. Methylation specific-high resolution melting (MS-HRM) analysis and Real-time quantitative PCR (RT-qPCR) experiment were performed to analyze the promoter methylation and mRNA expression levels of PAX2 and AIB1 genes in 102 breast tumors and adjacent normal breast specimens. We indicated that PAX2 expression is decreased in breast tissues due to hypermethylation in its promoter region. Compared to the adjacent normal tissues, the tumors exhibited significantly lower relative mRNA levels of PAX2 and increased expression of AIB1. Aberrant promoter methylation of PAX2 and overexpression of AIB1 was observed in tamoxifen resistance patients compared to the sensitive ones. Cox regression analysis exhibited that the increased promoter methylation status of PAX2 and overexpression of AIB1 remained as unfavorable identifiers which influence patients' survival independently. Our results revealed that the aberration in PAX2 promoter methylation and AIB1 overexpression are associated with the tamoxifen response in breast carcinoma patients. Further research is needed to demonstrate the potential of using PAX2 and AIB1 expression and their methylation-mediated regulation as predictive or prognostic biomarkers or as a new target therapy for better disease management.

RANKL is a new Epigenetic Biomarker for the Vasomotor Symptom During Menopause.

During menopausal transition, decreased level of estrogen brings a number of physiological problems and hormonal changes. In this study, promoter methylation of RANKL and FSHR genes were identified in 30 premenopausal and 35 postmenopausal women using methylation-specific high resolution melting (MS-HRM) analysis. The statistical analyses and their association with patient characteristics were performed by Pearson χ2 and Fisher’s exact test (p <0.05). The methylated RANKL gene was detected in 16 postmenopausal cases, and 12 (75.0%) of the RANKL methylated cases had hot flashes (p = 0.024). The methylated FSHR gene was detected in 18 postmenopausal cases, and 13 (75.0%) of the methylated cases had hot flashes (p = 0.028). In vitro studies demonstrated the association between RANKL expression, FSH level and hot flashes in the mouse. Although lack of epigenetic studies in this field proves our results crucial and therefore, our results showed magnitude of epigenetic profiles of Turkish Cypriot post-menopausal women. This was the first study which has investigated the RANKL and FSHR methylation and their relationship with hot flashes in postmenopausal women.

Abstract IA02: DNA repair gene promoter methylation patterns adapt and influence PARP inhibitor response

Abstract PARP inhibitor (PARPi) resistance in high-grade serous ovarian carcinoma (HGSOC) can be acquired as a result of restored homologous recombination (HR) due to secondary or reversion mutations in HR genes, such as BRCA1, BRCA2, and RAD51C, or due to loss of BRCA1 promoter methylation (meBRCA1). We have demonstrated that homozygous meBRCA1 can be lost or reverted to heterozygous methylation following treatment with platinum-based chemotherapy, resulting in HR-competent PARPi-resistant tumors. RAD51C promoter methylation (meRAD51C) is detected in approximately 2% of HGSOC cases and, as with meBRCA1, is associated with gene silencing and HR deficiency. We are exploring PARPi response in meRAD51C preclinical models to determine clinical relevance. Two patient-derived xenograft (PDX) models of HGSOC with RAD51C gene silencing caused by meRAD51C have distinct meRAD51C profiles (measured by methylation-specific high-resolution melt analysis and targeted bisulfite next-generation sequencing), and different responses to PARPi treatment pressure. PDX PH039 loses methylation and regains RAD51C expression after only 2 cycles of PARPi retreatment (niraparib), resulting in PARPi-refractory tumors by cycle 3-4. Illumina EPIC methylation array analysis of PH039 revealed increasing global methylation losses following each round of PARPi treatment. Lack of meRAD51C stability and rapid development of PARPi resistance in PH039 may be due to the high degree of meRAD51C heterogeneity within the tumor favoring selection of pre-existing HR-competent clones under PARPi pressure. In contrast, PDX 183 has a relatively homogeneous and stable meRAD51C profile. We have multiple examples of using unique PDX models to demonstrate various important features of PARPi resistance, including loss of promoter methylation for BRCA1 vs. RAD51C. Thus, meRAD51C confers response to PARPi in HGSOC, but PARPi treatment pressure can cause loss of methylation and drug resistance in some tumors. The contrasting PARPi responses of these PDX provide a platform for the study of meRAD51C stability in vivo and may present therapeutic opportunities to improve meRAD51C durability and PARPi responses in patients. Citation Format: Kasenija Nesic, Rachel M Hurley, Cordelia McGehee, Olga Kondrashova, Maria I. Harrell, Giada V. Zapparoli, Ashan Musafer, Ming E. Wong, John Weroha, Xiaonan Hou, Hu Li, Vivian Negron, Kevin Peterson, Paula Schneider, Elizabeth M. Swisher, Melissa Southey, Alexander Dobrovic, Matthew Wakefield, Scott H. Kaufmann, Clare L. Scott. DNA repair gene promoter methylation patterns adapt and influence PARP inhibitor response [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr IA02.

Hypermethylated RASSF1 and SLC5A8 promoters alongside BRAFV600E mutation as biomarkers for papillary thyroid carcinoma.

Circulating cell-free DNA (cfDNA) has been considered as a diagnostic source to track genetic and epigenetic alterations in cancer. We aimed to study mutation in addition to the methylation status in the promoter regions of RASSF1 and SLC5A8 genes in tissues and circulating free DNA samples of patients affected with papillary thyroid carcinoma (PTC) and thyroid nodules as controls. BRAFV600E mutation was studied by ARMS-scorpion real-time polymerase chain reaction method in 57 PTC and 45 thyroid nodule cases. Methylation status of RASSF1 and SLC5A8 promoter regions was analyzed by methylation-specific high-resolution melting curve analysis. BRAFV600E mutation was found in 39 (68.4%) out of 57 PTC tissue samples, while in 33 (49.1%) cases of cfDNA, this mutation was detected. The frequency of BRAFV600E mutation in cfDNA was significantly different between metastatic and nonmetastatic PTC cases (22 of 33 PTC cases vs. 5 of 34 thyroid nodule samples). Methylation levels of three promoter regions of SLC5A8 and proximal promoter region of RASSF1 was significantly different between PTC and thyroid nodule cases in both cfDNA and tissue DNA. In addition, the methylation status of these two genes in tissue DNA was reflected in methylation status observed in cfDNA. This study confirmed that BRAFV600E mutation is better for discrimination between papillary thyroid carcinoma and thyroid nodules. On the other hand, hypermethylation in the more proximal promoter regions to RASSF1 and SLC5A8 genes showed higher sensitivity and more acceptable specificity for this discrimination.

GEN-06 CLINICAL COURSE AFTER TUMOR RECURRENCE OF MGMT HYPERMETHYLATED GLIOBLASTOMA

MGMT methylation in glioblastoma is a biomarker for determining treatment responsiveness and predicting prognosis. We analyzed whether there were differences in the prognosis between glioblastoma with MGMT hypermethylation and other glioblastomas after tumor recurrence. We enrolled 184 patients who underwent radiation therapy and temozolomide chemotherapy after tumor resection for newly diagnosed glioblastoma. MGMT methylation was quantitatively analyzed using methylation-specific high resolution melting analysis. The cut-off value for MGMT methylation had a difference of 35% from the previous values. The subjects were split into three groups according to their MGMT methylation levels, 122 in the low (L) methylation group (levels of 0–34%), 40 in the medium (M) methylation group (levels of 35–69%), and 22 in the high (H) methylation group (levels of 70% or more). We mainly focused on and compared the progression after recurrence. The progression-free survival (PFS) rate and overall survival (OS) rate were significantly longer in the M and H groups than in the L group. There was no difference in PFS between group M and group H, but OS was significantly longer in group H. The details of treatment for the 16 of 22 patients who had recurrences in group H are as follows: temozolomide, n = 1; bevacizumab, n = 8; investigational drugs (peptide vaccines and immune checkpoint inhibitors), n = 3; and supportive care, n = 4. The median survival rate for these 16 patients after recurrence was 18 months. Even patients who received only supportive care had a median survival time ranging between 9 and 17 months. Our results indicate that MGMT hypermethylation in glioblastoma is effective to a certain degree with other treatments even after recurrence. Even patients who underwent only supportive care survived for a relatively longer period of time. Biologically, MGMT hypermethylation may be associated with a moderately slow-growing tumor.

PATH-01. MGMT METHYLATION CUTOFF VALUE IN QUANTITATIVE ANALYSIS RELATED TO PROGNOSIS OF NEWLY DIAGNOSED GLIOBLASTOMA

Abstract BACKGROUND MGMT promoter methylation is an important biomarker related to glioblastoma therapeutic response and prognosis. There are qualitative and quantitative methods as assays for MGMT methylation. Although the qualitative method is common, there is a disadvantage that low or high methylation cannot be distinguished. The quantitative method is an excellent method for evaluating methylation of tumors characterized by intratumoral heterogeneity like malignant glioma, but cutoff value of methylation that defines the prognosis of glioblastoma is unknown. Therefore, we examined the cutoff value of quantitative MGMT methylation assay determining the prognosis in glioblastoma. METHODS 180 newly diagnosed glioblastoma which underwent radiotherapy and temozolomide treatment after tumor removal in our department were included. MGMT methylation was quantitatively analyzed by methylation-specific high resolution melting (MS-HRM) analysis. For each level of methylation, progression-free survival (PFS) and overall survival (OS) were calculated and statistically analyzed. RESULTS In the low MGMT methylation cases in which the proportion of methylation was 25% or less in PFS and 30% or less in OS, no difference was observed in PFS and OS as compared with those of unmethylated cases. The cutoff value of MGMT methylation most contributing to survival was calculated to be 35% by the survival classification and regression tree method. CONCLUSION The prognosis for MGMT hypomethylated group is as poor as unmethylated one. In the quantitative MS-HRM method, we found that the value of MGMT methylation of 35% is useful as a cut off determining the prognosis of glioblastoma.

5-Aza-CdR promotes partial MGMT demethylation and modifies expression of different genes in oral squamous cell carcinoma

Treatment strategies for oral squamous cell carcinoma (OSCC) vary, depending on the stage of diagnosis. Surgery and radiotherapy are options for localized lesions for stage I patients, whereas chemotherapy is the main treatment for metastatic OSCC. However, aggressive tumors can relapse, frequently causing death. In an attempt to address this, novel treatment protocols using drugs that alter the epigenetic profile have emerged as an alternative to control tumor growth and metastasis. Therefore, the objective in this study was to investigate the effect of the demethylating drug 5-aza-CdR in SCC9 OSCC cells. SCC9 cells were treated with 5-Aza-CdR at concentrations of 0.3μM and 2μM for 24hours and 48hours. DNA methylation of the MGMT, BRCA1, APC, c-MYC, and hTERT genes were investigated by using the methylation-specific high-resolution melting technique. Real time-polymerase chain reaction and quantitative polymerase chain reaction were performed to analyze gene expression. 5-Aza-CdR promoted demethylation of MGMT and modified the transcription of all analyzed genes. Curiously, 5-aza-CdR at the concentration of 0.3μM was more efficient than 2μM in SCC9 cells. We observed that 5-aza-CdR led to MGMT demethylation, upregulated the transcription of 3 important tumor suppressor genes, and promoted the downregulation of c-Myc.

Aberrant DNA Methylation of SOCS1 Gene is Not Associated with Resistance to Imatinib Mesylate among Chronic Myeloid Leukemia Patients.

In exploring the cause of Imatinib Mesylate (IM) resistance among Chronic Myeloid Leukemia (CML) patients who do not harbor BCR-ABL dependent mechanism, BCR-ABL independent pathways are the most probable pathways that should be explored. In BCR-ABL independent pathway, SOCS1 plays an important role as it helps in regulating optimal JAK/STAT activity. To identify the association of SOCS1 gene hypermethylation in mediating IM Resistance. The SOCS1 promoter methylation level of 92 BCR-ABL non mutated IM resistant CML patients, 83 IM good response CML patients and 5 normal samples from healthy individuals were measured using Methylation Specific-High Resolution Melt (MS-HRM) analysis. Both primers used to amplify promoter region from -333 to -223 and from -332 to -188 showed less than 10% methylation in all CML and normal samples. Consequently, there was no significant difference in SOCS1 promoter methylation level between IM resistant and IM good response patients. SOCS1 promoter methylation level is not suitable to be used as one of the biomarkers for predicting the possibility of acquiring resistance among CML patients treated with IM.