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Biomedical subjects

Joachim P Steinbach

Publications and source records attributed to Joachim P Steinbach.

13 recordsLinked to original sources
PubMed2026

Age-associated epigenomic heterogeneity in papillary tumors of the pineal region: a multicenter YoungNOA investigation.

BACKGROUND: Papillary tumors of the pineal region (PTPR) are rare CNS neoplasms with adult and pediatric presentations, but whether age defines distinct molecular biology is unclear. METHODS: We assembled a multicenter retrospective cohort of 86 histologically confirmed PTPR with genome-wide DNA methylation data, comprising 62 adult and 24 pediatric tumors. Molecular subgroup, array platform, sex, and tumor purity were incorporated into multivariable models. Analyses included DNA methylation class assignment, differential methylation, copy-number variation (CNV), epigenetic mitotic-clock scores, methylation-based tumor microenvironment deconvolution, and descriptive survival evaluation. RESULTS: Adult and pediatric tumors mapped within the established PTPR-A and PTPR-B methylation framework rather than forming age-defined methylation classes. Pediatric tumors were enriched for PTPR-B (22 of 24 tumors [91.7%]) compared with adult tumors (39 of 62 [62.9%]). After adjustment for methylation-based subgroup as well as technical and biological covariates, 2,923 CpG probes were associated with age at a false discovery rate (FDR) threshold below 0.05, and 530 also met the prespecified effect-size threshold. Global methylation summaries were similar between age groups. CNV patterns were dominated by molecular subgroup; adjusted genomic CNV load was not independently associated with pediatric age. In contrast, epiTOC2 intrinsic rate score and the methylation signature represented by the first principal component (PC1) showed age-associated effects independent of molecular subgroup. Methylation-based deconvolution suggested a limited microenvironmental signal, with neutrophil fraction showing the most consistent adjusted association. CONCLUSIONS: Adult and pediatric PTPR share the established PTPR-A/PTPR-B framework. Pediatric tumors, particularly within PTPR-B, showed age-associated DNA methylation differences and higher epigenetic mitotic-clock (epiTOC2) scores in this retrospective cohort. These tissue-level associations do not establish clinical risk or treatment implications and require prospective clinical annotation and orthogonal validation.

Humans↗
PubMed2006

Phase II trial of lomustine plus temozolomide chemotherapy in addition to radiotherapy in newly diagnosed glioblastoma: UKT-03.

PURPOSE: To evaluate toxicity and efficacy of the combination of lomustine, temozolomide (TMZ) and involved-field radiotherapy in patients with newly diagnosed glioblastoma (GBM). PATIENTS AND METHODS: Thirty-one adult patients (median Karnofsky performance score 90; median age, 51 years) accrued in two centers received involved-field radiotherapy (60 Gy in 2-Gy fractions) and chemotherapy with lomustine 100 mg/m2 (day 1) and TMZ 100 mg/m2/d (days 2 to 6) with individual dose adjustments according to hematologic toxicity. RESULTS: A median of five courses (range, one to six courses) were delivered. WHO grade 4 hematotoxicity was observed in five patients (16%) and one of these patients died as a result of septicemia. Nonhematologic toxicity included one patient with WHO grade 4 drug-induced hepatitis (leading to discontinuation of lomustine and TMZ) and one patient with WHO grade 2 lung fibrosis (leading to discontinuation of lomustine). The progression-free survival (PFS) rate at 6 months was 61.3%. The median PFS was 9 months (95% CI, 5.3 to 11.7 months), the median overall survival time (MST) was 22.6 months (95% CI, 12.5 to not assessable), the 2-year survival rate was 44.7%. O6-methylguanine-DNA methyltransferase (MGMT) gene-promoter methylation in the tumor tissue was associated with longer PFS (P = .014, log-rank test) and MST (P = .037). CONCLUSION: The combination of lomustine, TMZ, and radiotherapy had acceptable toxicity and yielded promising survival data in patients with newly diagnosed GBM. MGMT gene-promoter methylation was a strong predictor of survival.

Administration, Oral↗
PubMed2005

UKT-04 trial of continuous metronomic low-dose chemotherapy with methotrexate and cyclophosphamide for recurrent glioblastoma.

Glioblastoma is a highly angiogenic tumor with a dismal prognosis. Continuous oral low-dose chemotherapy with methotrexate (MTX) and cyclophosphamide (CPM) has modest activity in heavily pretreated patients with breast cancer. We explored the efficacy of 100 mg CPM daily and 5 mg MTX twice weekly in relapsed glioblastoma. Ten patients, 22-59 years old, with a Karnofsky score of 50% or higher who had failed at least two chemotherapies were accrued. No toxicity was observed. No patient showed a complete or partial response. Five of 10 patients progressed within 2 months of therapy. Another five patients progressed after 3-4.5 months. The median time to progression was 2.5 months. The median overall survival after start of MTX/CPM was 6.9 months (range 0.5-18.8 months). Since the progression-free survival rate at 6 months was 0%, the trial was prematurely closed.

Adult↗
PubMed2005

Hypoxia sensitizes human malignant glioma cells towards CD95L-induced cell death.

Death ligands such as CD95 ligand (CD95L) have limited activity against glioma cells under normoxic conditions. Hypoxia is a critical aspect of the microenvironment of gliomas in vivo. We investigated the effect of co-exposure to acute hypoxia and CD95 ligand in three human malignant glioma cell lines with different susceptibility to CD95L under normoxic conditions. Hypoxia sensitized all three cell lines towards CD95L-induced cell death. Co-exposure resulted in apoptotic changes in the early phase, with gradual conversion to secondary necrosis with increasing length of hypoxia. The mitochondrial injury induced by hypoxia was enhanced by co-treatment, and caspase cleavage became prominent. Inhibition of the epidermal growth factor receptor (EGFR), although sensitizing glioma cells to CD95L under normoxia, protects glioma cells from hypoxia by reducing energy consumption. However, the opposing effects of EGFR signalling on death induced by CD95L or hypoxia were neutralized by co-exposure to hypoxia and CD95L. Furthermore, inhibition of protein synthesis by cycloheximide also reduced glucose consumption and conferred protection from hypoxia, but did not modulate CD95L-induced cell death under hypoxic conditions. These results suggest that death ligands may be useful to target hypoxic tumour cells resistant to conventional therapies or to complement strategies aiming at the induction of tumour hypoxia.

Apoptosis↗
PubMed2005

Temozolomide: a milestone in the pharmacotherapy of brain tumors.

Temozolomide (TMZ) is an alkylating agent earlier approved for recurrent anaplastic astrocytoma and approved for the treatment of newly diagnosed glioblastoma in the USA and Europe in 2005. TMZ shows good blood-brain barrier penetration and exhibits a favorable side effect profile. Its key mode of action appears to be methylation at N(7) and O(6)-positions of guanine. The level of expression and activity of the DNA repair enzyme O(6)-methylguanine DNA methyltransferase is thought to be a major predictor of response to TMZ. The demonstration of prolonged survival when TMZ was added to radiotherapy in the European Organisation for Research and Treatment of Cancer 26981/22981/NCIC CE.3 trial has been a breakthrough in the treatment of newly diagnosed glioblastoma. The early preliminary evidence for activity in recurrent malignant gliomas further resulted in a broad evaluation of TMZ for other tumors in neuro-oncology, mainly low-grade gliomas, brain metastases and primary cerebral lymphomas.

Antineoplastic Agents, Alkylating↗
PubMed2004

Co-inhibition of epidermal growth factor receptor and type 1 insulin-like growth factor receptor synergistically sensitizes human malignant glioma cells to CD95L-induced apoptosis.

Inhibition of epidermal growth factor receptor (EGFR) signaling sensitizes human malignant glioma cells to death ligand-induced apoptosis. However, tumor cells may compensate the loss of EGFR signaling by activation of the type 1 insulin-like growth factor receptor (IGF-1R). We here report that antagonism of the IGF-1R with the small-molecule inhibitor AG1024 in combination with inhibitors of the EGFR synergistically sensitizes human malignant glioma cells to CD95L-induced apoptosis. This cell death is p53-independent, but requires caspase 8 activity. The levels of the receptor, CD95, are not altered by the inhibitors alone or in combination. Analysis of the downstream signaling pathways reveals synergistic inhibition of ribosomal protein S6 phosphorylation by inhibitor co-treatment, suggesting an involvement of the mammalian target of rapamycin pathway. These findings suggest that adding inhibitors of IGF-1R may be a strategy to overcome escape from the anti-apoptotic effects of EGFR inhibition in malignant gliomas.

Apoptosis↗
PubMed2004

Inhibition of epidermal growth factor receptor signaling protects human malignant glioma cells from hypoxia-induced cell death.

Epidermal growth factor receptor (EGFR) signaling has become an important target for drug development because EGFR signaling enhances tumor cell proliferation, migration, and invasion and inhibits apoptosis. However, the results of clinical trials using EGFR inhibitors in patients with solid tumors have been disappointing. Here, we report a protective effect of the EGFR inhibitors AG1478 and PD153035 against cell death induced by acute hypoxia, which contrasts with their proapoptotic effects under normoxia. Under hypoxic conditions, both agents reduced glucose consumption, delayed ATP depletion, and preserved the mitochondrial membrane potential. Exposure either to hypoxia or the EGFR inhibitors under normoxic conditions resulted in the dephosphorylation of ribosomal protein S6, a player in the energy and nutrient-sensing pathway governed by mammalian target-of-rapamycin (mTOR). Combined inhibition of phosphatidylinositol 3'-kinase (PI3K) and extracellular signal-regulated kinase-1/2 (ERK1/2) mimicked the protective effects of EGFR inhibition on hypoxia-induced cell death and protein S6 dephosphorylation. These results caution that therapies targeting EGFR signaling pathways can protect tumor cells from acute hypoxia.

Adenosine Triphosphate↗
PubMed2004

Apoptosis in Gliomas: Molecular Mechanisms and Therapeutic Implications.

Understanding apoptosis is often considered a key to understand the genesis of tumors and to devise innovative strategies for their treatment. Similar to other types of cancer, essential pathways regulating apoptosis are also disrupted in malignant gliomas, notably the cell cycle control mechanisms regulated by the p53 and retinoblastoma (RB) proteins and their homologs. Moreover, cultured glioma cells appear not to activate the extrinsic death receptor-dependent apoptotic pathway in response to irradiation or cytotoxic drugs. A preferential expression of antiapoptotic rather than proapoptotic BCL-2 family proteins and high level expression of inhibitor-of-apoptosis proteins (IAP) may be responsible for the failure of glioma cells to activate caspases in response to apoptotic stimuli. Although apoptosis does occur spontaneously in malignant gliomas in vivo, there is little evidence that the current modes of non-surgical treatment, radiotherapy and chemotherapy, mediate their effects via induction of apoptosis, with the possible exception of anaplastic oligodendrogliomas which often show striking tumor regression on neuroimaging. Yet, the induction of apoptosis plays a conceptual role in the majority of novel experimental approaches to malignant glioma which are currently evaluated in cell culture and preclinical rodent models.

Journal Article↗
PubMed2002

Modulation of growth and radiochemosensitivity of human malignant glioma cells by acidosis.

BACKGROUND: Glioblastoma commonly is characterized by hypoxia and acidosis and the histologic features of tissue necrosis and neovascularization. Current approaches of adjuvant radiochemotherapy for patients with glioblastoma have only a modest impact on the natural course of this disease. METHODS: The authors examined the effects of acidosis on growth and response to irradiation and chemotherapy in cultured human malignant glioma cells. RESULTS: The authors found that mild acidosis (pH 7.0) inhibited the growth of cell lines that retained wild type p53 activity but did not inhibit the growth of cell lines that were devoid of p53 function. Transfer of a dominant-negative p53 gene into p53 wild type cells failed to override the acidosis-conferred growth arrest, suggesting that loss of p53 activity per se does not mediate escape from acidosis-induced growth inhibition. Moderate acidosis (pH 6.6) inhibited the growth of all cell lines. Acidosis-mediated growth arrest was not associated with a specific type of cell cycle arrest, e.g., in G0/G1 or G2/M phase. Acidosis did not result in consistent changes in radiosensitivity; however, it enhanced the cytotoxic effects of lomustine but conferred protection from topotecan, vincristine, teniposide, and cisplatin cytotoxicity. Lomustine exhibited enhanced stability at low pH, providing a putative mechanism for the enhanced cytotoxic effects of lomustine in acidotic conditions. Decreased sensitivity to the other drugs did not result from altered multidrug resistance drug transport activity. CONCLUSIONS: Taken together, the current results suggest that tissue acidosis may be an important determinant of glioma cell responses to adjuvant radiochemotherapy. The superior activity of nitrosoureas, such as lomustine, compared with other agents in patients with glioblastoma may result in part from prolonged drug stability in an acidotic microenvironment.

Acidosis↗
PubMed2002

Identification of CD70-mediated apoptosis of immune effector cells as a novel immune escape pathway of human glioblastoma.

Interactions of CD70, a tumor necrosis factor-related cell surface ligand and its receptor, CD27, are thought to play an important role for T-, B-, and natural killer-cell activation. However, ligation of CD27 can also induce apoptosis. Human glioblastoma is paradigmatic for cancer-associated immunosuppression. We identified CD70 as a radioinducible gene in U87 MG glioma cells. A screening of a panel of human glioma cell lines revealed that 11 of 12 cell lines expressed CD70 mRNA and protein. Two human neuroblastoma cell lines did not express CD70. CD70 mRNA expression was enhanced by irradiation in 8 of 12 glioma cell lines in a p53-independent manner. No alteration in CD70 expression was observed after glioma cell exposure to cytotoxic drugs such as lomustine. CD70 protein was also detected by immunocytochemistry in 5 of 12 glioblastomas and 3 of 4 anaplastic astrocytomas in vivo. CD27 expression was not detected in any glioma cell line, and there was no evidence for autocrine or backward signaling of the CD70 system in human glioma cells. Unexpectedly, CD70 expressed on glioma cells did not increase the immunogenicity of glioma cells in vitro. In contrast, CD70-positive glioma cells induced apoptosis in peripheral blood mononuclear cells (PBMCs) in a CD70-dependent manner. Neutralization of CD70 expressed on glioma cells prevented apoptosis and enhanced the release of tumor necrosis factor-alpha in cocultures of glioma cells and PBMCs. The effects of CD70-expressing glioma cells on PBMCs were mimicked by agonistic CD27 antibodies. Conversely, the shedding of CD27 by PBMCs was identified as a possible escape mechanism from glioma cell-induced CD70-dependent apoptosis. Thus, induction of B-cell and T-cell apoptosis via interactions of CD70 expressed on glioma cells and CD27 expressed on B and T cells may be a novel way for the immune escape of malignant gliomas.

Antigens, CD↗
PubMed2002

Mechanisms of apoptosis in central nervous system tumors: application to theory.

Apoptosis is a key concept for the successful therapy of brain tumors. This review focuses on the mechanisms of apoptosis occurring spontaneously in malignant gliomas, discusses the different methods employed to assess apoptosis in vivo and in vitro, and considers the value of quantifying apoptosis in surgical biopsies for diagnosis and prognosis. Further, novel strategies to induce apoptosis in human malignant glioma cells are reviewed, including experimental therapy with death ligands, methods for sensitizing glioma cells to the induction of apoptosis, p53 gene transfer, and approaches to target the expression of therapeutic genes selectively to tumor cells.

Apoptosis↗
PubMed2002

CD95-mediated apoptosis of human glioma cells: modulation by epidermal growth factor receptor activity.

The death ligands CD95L and Apo2L/TRAIL are promising investigational agents for the treatment of malignant glioma. EGFR is overexpressed in a significant proportion of malignant gliomas in vivo. Here, we report that CD95L-induced cell death is enhanced by EGFR inhibition using tyrphostine AG1478 in 7 of 12 human malignant glioma cell lines. Conversely, CD95-mediated and Apo2L-induced cell death are both inhibited by overexpression of EGFR in LN-229 cells. CD95L-induced cell death augmented by AG1478 is accompanied by enhanced processing of caspase 8. LN-229 cells overexpressing the viral caspase inhibitor, crm-A, are not sensitized to CD95L-induced cell death by AG1478, indicating that EGFR exerts its antiapoptotic properties through a caspase 8-dependent pathway. These data define a modulatory effect of EGFR-activity on death ligand-induced apoptosis and indicate that EGFR inhibition is likely to improve the efficacy of death ligand-based cancer therapies. Furthermore, it is tempting to speculate that EGFR amplification protects tumor cells from death ligand-mediated host immune responses in vivo and that EGFR's effects on death receptor-mediated apoptosis may explain the anti-tumor effects of non-cytotoxic, unarmed anti-EGFR family antibodies.

Apoptosis↗