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Abstract Background Combined chemoradiation offers a promising therapeutic strategy for dogs with glioma. The alkylating agents temozolomide (TMZ) and lomustine (CCNU) penetrate the blood‐brain barrier, and doses for dogs are established. Whether such combinations are clinically advantageous remains to be explored together with tumour‐specific markers. Objective To investigate if triple combination of lomustine, temozolomide and irradiation reduces canine glioma cell survival in vitro. Methods We evaluated the sensitising effect of CCNU alone and in combination with TMZ‐irradiation in canine glioma J3T‐BG cells and long‐term drug‐exposed subclones by using clonogenic survival and proliferation assays. Bisulphite‐SEQ and Western Blot were used to investigate molecular alterations. Results TMZ (200 μM) or CCNU alone (5 μM) reduced the irradiated survival fraction (4 Gy) from 60% to 38% (p = 0.0074) and 26% (p = 0.0002), respectively. The double‐drug combination reduced the irradiated survival fraction (4 Gy) more potently to 12% (p < 0.0001). After long‐term drug exposure, both subclones show higher IC50 values against CCNU and TMZ. For CCNU‐resistant cells, both, single‐drug CCNU (p = 0.0006) and TMZ (p = 0.0326) treatment combined with irradiation (4 Gy) remained effective. The double‐drug‐irradiation combination reduced the cell survival by 86% (p < 0.0001), compared to 92% in the parental (nonresistant) cell line. For TMZ‐resistant cells, only the double‐drug combination with irradiation (4 Gy) reduced the cell survival by 88% (p = 0.0057) while single‐drug treatment lost efficacy. Chemoresistant cell lines demonstrated higher P‐gp expression while MGMT‐methylation profile analysis showed a general high methylation level in the parental and long‐term treated cell lines. Conclusions Our findings indicate that combining CCNU with TMZ‐irradiation significantly reduces canine glioma cell survival. Such a combination could overcome current challenges of therapeutic resistance to improve overall patient survival.

Background: Combined chemoradiation offers a promising therapeutic strategy for dogs with glioma. The alkylating agents temozolomide (TMZ) and lomustine (CCNU) penetrate the blood‐brain barrier, and doses for dogs are established. Whether such combinations are clinically advantageous remains to be explored together with tumour‐specific markers. Objective: To investigate if triple combination of lomustine, temozolomide and irradiation reduces canine glioma cell survival in vitro. Methods: We evaluated the sensitising effect of CCNU alone and in combination with TMZ‐irradiation in canine glioma J3T‐BG cells and long‐term drug‐exposed subclones by using clonogenic survival and proliferation assays. Bisulphite‐SEQ and Western Blot were used to investigate molecular alterations. Results: TMZ (200 μM) or CCNU alone (5 μM) reduced the irradiated survival fraction (4 Gy) from 60% to 38% (p = 0.0074) and 26% (p = 0.0002), respectively. The double‐drug combination reduced the irradiated survival fraction (4 Gy) more potently to 12% (p < 0.0001). After long‐term drug exposure, both subclones show higher IC50 values against CCNU and TMZ. For CCNU‐resistant cells, both, single‐drug CCNU (p = 0.0006) and TMZ (p = 0.0326) treatment combined with irradiation (4 Gy) remained effective. The double‐drug‐irradiation combination reduced the cell survival by 86% (p < 0.0001), compared to 92% in the parental (nonresistant) cell line. For TMZ‐resistant cells, only the double‐drug combination with irradiation (4 Gy) reduced the cell survival by 88% (p = 0.0057) while single‐drug treatment lost efficacy. Chemoresistant cell lines demonstrated higher P‐gp expression while MGMT‐methylation profile analysis showed a general high methylation level in the parental and long‐term treated cell lines. Conclusions: Our findings indicate that combining CCNU with TMZ‐irradiation significantly reduces canine glioma cell survival. Such a combination could overcome current challenges of therapeutic resistance to improve overall patient survival. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is the most prevalent and deadly primary brain tumor. The current treatment for GBM includes adjuvant chemotherapy with temozolomide (TMZ), radiation therapy, and surgical tumor excision. There is still an issue because 50% of patients with GBM who get TMZ have low survival rates due to TMZ resistance. The activation of several DNA repair mechanisms, such as Base Excision Repair (BER), DNA Mismatch Repair (MMR), and O-6- Methylguanine-DNA Methyltransferase (MGMT), is the main mechanism via which TMZ resistance develops. The zinc-finger DNA-binding enzyme poly (ADP-ribose) polymerase-1 (PARP1), which is activated by binding to DNA breaks, affects the activation of the MGMT, BER, and MMR pathway deficiency, which results in TMZ resistance in GBM. PARP inhibitors have been studied recently as sensitizing medications to increase TMZ potency. The first member of the PARP inhibitor family to be identified was Olaparib. It inhibits PARP1 and PARP2, which causes apoptosis in cancer cells and DNA strand break. Olaparib is currently investigated as a radio- and/or chemo-sensitizer in addition to being used as a single agent because it may increase the cytotoxic effects of other treatments. This review addresses Olaparib and its significance in treating TMZ resistance in GBM., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Abstract Background Similar to human glioblastoma patients, glial tumours in dogs have high treatment resistance and a guarded prognosis. In human medicine, the addition of temozolomide to radiotherapy leads to a favourable outcome in vivo as well as a higher antiproliferative effect on tumour cells in vitro. Objectives The aim of the study was to determine the radio‐ and temozolomide‐sensitivity of three canine glial tumour cell lines and to investigate a potential additive cytotoxic effect in combined treatment. Additionally, we wanted to detect the level of MGMT promoter methylation in these cell lines and to investigate a potential association between MGMT promoter methylation and treatment resistance. Methods Cells were treated with various concentrations of temozolomide and/or irradiated with 4 and 8 Gy. Radiosensitization by temozolomide was evaluated using proliferation assay and clonogenic assay, and MGMT DNA methylation was investigated using bisulfite next‐generation sequencing. Results In all tested canine cell lines, clonogenicity was inhibited significantly in combined treatment compared to radiation alone. All canine glial cell lines tested in this study were found to have high methylation levels of MGMT promoter. Conclusions Hence, an additive effect of combined treatment in MGMT negative canine glial tumour cell lines in vitro was detected. This motivates to further investigate the association between treatment resistance and MGMT, such as MGMT promoter methylation status.

Background: Similar to human glioblastoma patients, glial tumours in dogs have high treatment resistance and a guarded prognosis. In human medicine, the addition of temozolomide to radiotherapy leads to a favourable outcome in vivo as well as a higher antiproliferative effect on tumour cells in vitro. Objectives: The aim of the study was to determine the radio‐ and temozolomide‐sensitivity of three canine glial tumour cell lines and to investigate a potential additive cytotoxic effect in combined treatment. Additionally, we wanted to detect the level of MGMT promoter methylation in these cell lines and to investigate a potential association between MGMT promoter methylation and treatment resistance. Methods: Cells were treated with various concentrations of temozolomide and/or irradiated with 4 and 8 Gy. Radiosensitization by temozolomide was evaluated using proliferation assay and clonogenic assay, and MGMT DNA methylation was investigated using bisulfite next‐generation sequencing. Results: In all tested canine cell lines, clonogenicity was inhibited significantly in combined treatment compared to radiation alone. All canine glial cell lines tested in this study were found to have high methylation levels of MGMT promoter. Conclusions: Hence, an additive effect of combined treatment in MGMT negative canine glial tumour cell lines in vitro was detected. This motivates to further investigate the association between treatment resistance and MGMT, such as MGMT promoter methylation status. [ABSTRACT FROM AUTHOR]

Background: The dysregulation of Isocitrate dehydrogenase (IDH) and the subsequent production of 2-Hydroxyglutrate (2HG) may alter the expression of epigenetic proteins in Grade 4 astrocytoma. The interplay mechanism between IDH, O-6-methylguanine-DNA methyltransferase ( MGMT) -promoter methylation, and protein methyltransferase proteins-5 ( PRMT5) activity, with tumor progression has never been described., Methods: A retrospective cohort of 34 patients with G4 astrocytoma is classified into IDH-mutant and IDH-wildtype tumors. Both groups were tested for MGMT -promoter methylation and PRMT5 through methylation-specific and gene expression PCR analysis. Inter-cohort statistical significance was evaluated., Results: Both IDH-mutant WHO grade 4 astrocytomas (n = 22, 64.7%) and IDH-wildtype glioblastomas (n = 12, 35.3%) had upregulated PRMT5 gene expression except in one case. Out of the 22 IDH-mutant tumors, 10 (45.5%) tumors showed MGMT -promoter methylation and 12 (54.5%) tumors had unmethylated MGMT . All IDH-wildtype tumors had unmethylated MGMT . There was a statistically significant relationship between MGMT -promoter methylation and IDH in G4 astrocytoma ( p -value = 0.006). Statistically significant differences in progression-free survival (PFS) were also observed among all G4 astrocytomas that expressed PRMT5 and received either temozolomide (TMZ) or TMZ plus other chemotherapies, regardless of their IDH or MGMT -methylation status ( p -value=0.0014). Specifically, IDH-mutant tumors that had upregulated PRMT5 activity and MGMT -promoter methylation, who received only TMZ, have exhibited longer PFS., Conclusions: The relationship between PRMT5 , MGMT -promoter, and IDH is not tri-directional. However, accumulation of D2-hydroxyglutarate (2-HG), which partially activates 2-OG-dependent deoxygenase, may not affect their activities. In IDH-wildtype glioblastomas, the 2HG-2OG pathway is typically inactive, leading to PRMT5 upregulation. TMZ alone, compared to TMZ-plus, can increase PFS in upregulated PRMT5 tumors. Thus, using a PRMT5 inhibitor in G4 astrocytomas may help in tumor regression., Competing Interests: The authors have no relevant conflict of interest to disclose., (© 2024 Kurdi et al.)

Background/Aims: Valproic acid (VPA), an anticonvulsant and mood-stabilizing drug is used to treat epileptic seizure of glioblastoma patients. Besides its antiepileptic activity, VPA has been attributed further functions that improve the clinical outcome of glioblastoma patients. Those comprise the inhibition of some histone deacetylase (HDAC) isoforms which reportedly may result in radiosensitization. Retrospective analysis of patient data, however, could not unequivocally confirm a prolonged survival of glioblastoma patients receiving VPA. The present study aimed to identify potential VPA targets at the cellular level. Methods: To this end, the effect of VPA on metabolism, Ca2+-, biochemical and electro-signaling, cell-cycling, clonogenic survival and transfilter migration was analyzed in three human glioblastoma lines (T98G, U-87MG, U251) by MTT assay, Ca2+ imaging, immunoblotting, patch-clamp recording, flow cytometry, delayed plating colony formation and modified Boyden chamber assays, respectively. In addition, the effect of VPA on clonogenic survival of primary glioblastoma spheroid cultures treated with temozolomide and fractionated radiation was assessed by limited dilution assay. Results: In 2 of 3 glioblastoma lines, clinical relevant concentrations of VPA slightly slowed down cell cycle progression and decreased clonogenic survival. Furthermore, VPA induced Ca2+ signaling which was accompanied by pronounced K+ channel activity and transfilter cell migration. VPA did not affect metabolic NAD(P)H formation or radioresistance of the glioblastoma lines. Finally, VPA did not impair clonogenic survival or radioresistance of temozolomide-treated primary spheroid cultures. Conclusions: Combined, our in vitro data do not propose a general use of VPA as a radiosensitizer in anti-glioblastoma therapy.

Glioblastoma multiforme (GBM) is one of the most aggressive and malignant forms of brain tumors. Despite recent advances in operative and postoperative treatments, it is almost impossible to perform complete resection of these tumors owing to their invasive and diffuse nature. Several natural plant-derived products, however, have been demonstrated to have promising therapeutic effects, such that they may serve as resources for anticancer drug discovery. The therapeutic effects of one such plant product, n-butylidenephthalide (BP), are wide-ranging in nature, including impacts on cancer cell apoptosis, cell cycle arrest, and cancer cell senescence. The compound also exhibits a relatively high level of penetration through the blood-brain barrier (BBB). Taken together, its actions have been shown to have anti-proliferative, anti-chemoresistance, anti-invasion, anti-migration, and anti-dissemination effects against GBM. In addition, a local drug delivery system for the subcutaneous and intracranial implantation of BP wafers that significantly reduce tumor size in xenograft models, as well as orthotopic and spontaneous brain tumors in animal models, has been developed. Isochaihulactone (ICL), another kind of plant product, possesses a broad spectrum of pharmacological activities, including impacts on cancer cell apoptosis and cell cycle arrest, as well as anti-proliferative and anti-chemoresistance effects. Furthermore, these actions have been specifically shown to have cancer-fighting effects on GBM. In short, the results of various studies reviewed herein have provided substantial evidence indicating that BP and ICH are promising novel anticancer compounds with good potential for clinical applications. [ABSTRACT FROM AUTHOR]

Background/Aims: Valproic acid (VPA), an anticonvulsant and mood-stabilizing drug is used to treat epileptic seizure of glioblastoma patients. Besides its antiepileptic activity, VPA has been attributed further functions that improve the clinical outcome of glioblastoma patients. Those comprise the inhibition of some histone deacetylase (HDAC) isoforms which reportedly may result in radiosensitization. Retrospective analysis of patient data, however, could not unequivocally confirm a prolonged survival of glioblastoma patients receiving VPA. The present study aimed to identify potential VPA targets at the cellular level. Methods: To this end, the effect of VPA on metabolism, Ca2+-, biochemical and electro-signaling, cell-cycling, clonogenic survival and transfilter migration was analyzed in three human glioblastoma lines (T98G, U-87MG, U251) by MTT assay, Ca2+ imaging, immunoblotting, patch-clamp recording, flow cytometry, delayed plating colony formation and modified Boyden chamber assays, respectively. In addition, the effect of VPA on clonogenic survival of primary glioblastoma spheroid cultures treated with temozolomide and fractionated radiation was assessed by limited dilution assay. Results: In 2 of 3 glioblastoma lines, clinical relevant concentrations of VPA slightly slowed down cell cycle progression and decreased clonogenic survival. Furthermore, VPA induced Ca2+ signaling which was accompanied by pronounced K+ channel activity and transfilter cell migration. VPA did not affect metabolic NAD(P)H formation or radioresistance of the glioblastoma lines. Finally, VPA did not impair clonogenic survival or radioresistance of temozolomide-treated primary spheroid cultures. Conclusions: Combined, our in vitro data do not propose a general use of VPA as a radiosensitizer in anti-glioblastoma therapy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation status is an important marker for glioblastoma multiforme (GBM), there is considerable variability in the clinical outcome of patients with similar methylation profles. OBJECTIVE: We examined whether a MicroRNA (miRNA) signature can be identified for predicting clinical outcomes and helping in treatment decisions. METHODS: The differentially expressed miRNAs were evaluated in 6 pairs of short- (≼ 450 days) and long-term survivors (> 450 days) by using microarray. Real time quantitative PCR (qRT-PCR) was applied to further verify screened miRNAs with a greater number of samples (n = 48). Meanwhile, functional interpretation of miRNA profile was carried out based on miRNAtarget databases. In addition, MGMT promoter methylation status was tested by means of pyrosequencing (PSQ) testing. RESULTS: Six miRNAs were upregulated in the long-term survival group (fold change ≽ 2.0, P < 0.05). The further verification by qRT-PCR indicated that the increase in let-7g-5p, miR-139-5p, miR-17-5p and miR-9-3p level in long-term survivors was statistically significant. Kaplan-Meier survival analysis showed that high expression of a prognostic 4-miRNA signature was significantly associated with good patient survival (p = 0.0012). The signature regulated signaling pathways including Calcium, MAPK, ErbB, mTOR and cell cycle involved in carcinogenesis from glial progenitor cell to primary GBM. CONCLUSIONS: The 4-miRNA signature was identified as an independent prognostic biomarker that identified patients who have a favorable outcome. [ABSTRACT FROM AUTHOR]

Glioblastoma multiforme (GBM) is one of the most aggressive and malignant forms of brain tumors. Despite recent advances in operative and postoperative treatments, it is almost impossible to perform complete resection of these tumors owing to their invasive and diffuse nature. Several natural plant-derived products, however, have been demonstrated to have promising therapeutic effects, such that they may serve as resources for anticancer drug discovery. The therapeutic effects of one such plant product, n-butylidenephthalide (BP), are wide-ranging in nature, including impacts on cancer cell apoptosis, cell cycle arrest, and cancer cell senescence. The compound also exhibits a relatively high level of penetration through the blood-brain barrier (BBB). Taken together, its actions have been shown to have anti-proliferative, anti-chemoresistance, anti-invasion, anti-migration, and anti-dissemination effects against GBM. In addition, a local drug delivery system for the subcutaneous and intracranial implantation of BP wafers that significantly reduce tumor size in xenograft models, as well as orthotopic and spontaneous brain tumors in animal models, has been developed. Isochaihulactone (ICL), another kind of plant product, possesses a broad spectrum of pharmacological activities, including impacts on cancer cell apoptosis and cell cycle arrest, as well as anti-proliferative and anti-chemoresistance effects. Furthermore, these actions have been specifically shown to have cancer-fighting effects on GBM. In short, the results of various studies reviewed herein have provided substantial evidence indicating that BP and ICH are promising novel anticancer compounds with good potential for clinical applications.

Abstract: Colorectal cancer, a leading cause of mortality worldwide, is a multistep disorder that results from the alteration of genetic and epigenetic mechanisms under contextual influence. Epigenetic aberrations, including DNA methylation, histone modifications, chromatin remodeling and non-coding RNAs, affect every aspect of tumor development from initiation to metastasis. Cancer stem cell promotion is also included in the wide spectrum of epigenetic dysregulations. Elucidation of this complex crosstalk network may offer new insights in the molecular interactions involved in the pathogenesis of colorectal carcinogenesis. In the era of translational medicine new horizons are opened for the pursuit of personalized therapeutic approaches and the development of novel and accurate diagnostic, prognostic and therapy-assessment markers. This review discusses the implications of epigenetic mechanisms in tumor biology and their applications “from bench to bedside”. [Copyright &y& Elsevier]

Highlights: [•] Genetic mutations found in familial pituitary adenomas are very rare in sporadic tumors. [•] Multiple tumor suppressive genes are inactivated in sporadic tumors by epigenetic mutations. [•] We discuss the current status of twenty genes which are lost or down regulated in sporadic pituitary tumors. [•] These genes are functionally connected to tumor suppressors RB and p53. [ABSTRACT FROM AUTHOR]

Abstract: Gastric cancer is one of the most common malignancies and remains the second leading cause of cancer-related death worldwide. Over 70% of new cases and deaths occur in developing countries. In the early years of the molecular biology revolution, cancer research mainly focuses on genetic alterations, including gastric cancer. Epigenetic mechanisms are essential for normal development and maintenance of tissue-specific gene expression patterns in mammals. Disruption of epigenetic processes can lead to altered gene function and malignant cellular transformation. Recent advancements in the rapidly evolving field of cancer epigenetics have shown extensive reprogramming of every component of the epigenetic machinery in cancer, including DNA methylation, histone modifications, nucleosome positioning, noncoding RNAs, and microRNAs. Aberrant DNA methylation in the promoter regions of gene, which leads to inactivation of tumor suppressor and other cancer-related genes in cancer cells, is the most well-defined epigenetic hallmark in gastric cancer. The advantages of gene methylation as a target for detection and diagnosis of cancer in biopsy specimens and non-invasive body fluids such as serum and gastric washes have led to many studies of application in gastric cancer. This review focuses on the most common and important phenomenon of epigenetics, DNA methylation, in gastric cancer and illustrates the impact epigenetics has had on this field. [Copyright &y& Elsevier]

Summary: DNA methylation markers provide a powerful tool to make diagnoses based on genetic material obtained directly from tumors or from “remote” locations such as sputum, pleural fluid, or serum. In particular when limited cell numbers are available, amplifyable DNA markers can provide a very sensitive tool for cancer detection and classification. Malignant mesothelioma (MM), an aggressive cancer strongly associated with asbestos exposure, can be difficult to distinguish from adenocarcinoma of the lung when limited material is available. In an attempt to identify molecular markers for MM and adenocarcinoma, we examined the DNA methylation status of 14 loci. Analysis of methylation levels in 10 MM and 8 adenocarcinoma cell lines showed that methylation of APC was significantly elevated in adenocarcinoma compared to MM cell lines (P=0.0003), while methylation of CDH1 was higher in MM (P<0.02). Subsequent examination of the methylation status of the 14 loci in 6 MM and 7 adenocarcinoma primary tumors, which yielded similar methylation profiles, supported these observations. Comparison of methylation in MM cell lines and tumors versus non-tumor lung tissue indicated that APC exhibits less methylation in MM (P=0.003) while RASSF1, PGR1, ESR1, and CDH1 show more methylation in MM, the latter two showing the most significant difference between the two tissue types (P≤0.0001). Comparison of methylation in adenocarcinoma cell lines and tumors versus non-tumor lung tissue showed methylation of ESR1, PGR1 and RASSF1 to be significantly elevated in adenocarcinoma, with RASSF1 being most significant (P=0.0002). Thus, with the examination of 14 loci, we have identified 5 candidates that show potential for distinguishing between MM, adenocarcinoma and/or non-cancer lung. Our observations support the strong potential of methylation markers as tools for accurate diagnosis of neoplasms in and around the lung. [Copyright &y& Elsevier]

Background: The importance of the O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status as a predictive factor for the response to chemotherapy with temozolomide is well established. Its significance though at stratifying glioblastoma (GBM) patients in regard to their prognostic factors and the impact of surgical approach on them has not been identified., Objective: To reveal possible differences in the prognostic factors and the impact of surgery between GBM patients stratified according to their MGMT status., Methods: The authors retrospectively analyzed 186 patients with a newly diagnosed primary supratentorial GBM treated with surgical resection followed by standard radiation and chemotherapy. A prospective quantitative volumetric analysis of tumor characteristics identified on magnetic resonance imaging was performed., Results: For the 109 patients with unmethylated MGMT promoter, extent of resection (EOR) represented independent predictor of survival, whereas residual tumor volume (RTV), Karnofsky Performance Score, and age were found to be independent prognostic factors of survival for the 77 patients with methylated MGMT promoter. For the group of patients with unmethylated and the group with methylated MGMT promoter, an EOR threshold of 70% and 98% and an RTV threshold of 1.5 and 1 cm3 were identified, respectively., Conclusion: The selection of patients according to the MGMT promoter methylation status resulted in different prognostic factors and different resection thresholds for each patient population. A survival benefit seen from 70% EOR threshold in patients with MGMT unmethylated GBM supports the doctrine of maximum safe resection rather than the "all-or-nothing" approach., (© Congress of Neurological Surgeons 2021.)

We report a case of an unusual glioma termed "primitive polar spongioblastoma" that displayed characteristic palisading tumor cells at the light microscopic level. The patient was a 52-year-old woman who underwent subtotal removal for a left frontotemporal tumor. The palisading pattern was present throughout the tumor. Several glial markers were revealed by immunohistochemical examination, but no neuronal markers were observed. Genetic studies showed O-6-methylguanine-DNA methyltransferase (MGMT) methylation, wild type IDH1, and the absence of 1p/19q loss of heterozygosity (LOH) in the tumor genes. Based on histological and genetic features, this tumor might not be suited to any of neuroepithelial tumor in the recent WHO classification. We consider that cases such as this should be temporarily set under a separate heading and be entrusted to future investigation after more cases have been accumulated., (© 2010 Japanese Society of Neuropathology.)