Biomedical subjects

Douglas C Miller

Publications and source records attributed to Douglas C Miller.

At least 19 recordsLinked to original sources

PubMed2007

Outcome for young children newly diagnosed with ependymoma, treated with intensive induction chemotherapy followed by myeloablative chemotherapy and autologous stem cell rescue.

BACKGROUND: The purpose of this study is to investigate the efficacy of an intensive chemotherapy induction regimen followed by myeloablative chemotherapy and autologous hematopoietic stem cell rescue (AHSCR) in children with newly diagnosed ependymoma. PATIENTS AND METHODS: Twenty-nine children less than 10 years of age at diagnosis of ependymoma were enrolled on the "Head Start" studies. Twenty-four patients with localized disease received an induction regimen including five cycles of chemotherapy (cisplatin, vincristine, etoposide cyclophosphamide, and high dose methotrexate for patients with metastatic disease). Following induction, individuals without evidence of disease proceeded to marrow-ablative chemotherapy (thiotepa, carboplatin, and etoposide) with AHSCR. RESULTS: The estimated 5-year event free survival (EFS) and overall survival (OS) from diagnosis were 12% (+/-6%) and 38% (+/-10%), respectively. The toxic mortality amongst this group of 29 patients was 10.3%. Younger age (less than 18 months at diagnosis) was the only statistically significant prognostic factor. The estimated 5-year OS rate for the five patients with metastatic disease at presentation was 80% (+/-18%). Overall, radiation-free survival at 5 years from diagnosis was 8% (+/-5%). CONCLUSIONS: The use of an intensive induction chemotherapy regimen including myeloablative chemotherapy followed by AHSCR in newly diagnosed young children with ependymoma is not superior to other previously reported chemotherapeutic strategies.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2007

Direct identification of proteins from T47D cells and murine brain tissue by matrix-assisted laser desorption/ionization post-source decay/collision-induced dissociation.

The purpose of this study is to determine the feasibility of the direct matrix-assisted laser desorption/ionization (MALDI) identification of proteins in fixed T47D breast cancer cells and murine brain tissues. The ability to identify proteins from cells and tissue may lead to biomarkers that effectively predict the onset of defined disease states, and their dynamic behavior could be an important hint for drug target discoveries. Direct tissue application of trypsin allows protein identification in cells and tissues, while maintaining spatial integrity and intracellular organization. Using a chemical printer, matrix was co-registered on trypsinized human T47D breast cancer cells and cryo-preserved sections of murine brain tissue, followed by MALDI post-source decay (PSD) or MALDI collision-induced dissociation (CID), respectively. Mass-to-charge (m/z) data from the cells and brain tissues were processed using Mascot software interrogation of the National Center for Biotechnology Information (NCBI) database. Histone H2B was identified from cultured T47D human breast cancer cells. Tubulin beta2 was identified from mouse brain cortex following an induced stroke. These results suggest that MALDI PSD/CID, combined with bioinformatics, can be used for the direct identification of proteins from cells and tissues. Refinements in preparation techniques may improve this approach to provide a tool for quantitative proteomics and clinical analysis.

Animals↗

PubMed2006

Results of surgical resection for progression of brain metastases previously treated by gamma knife radiosurgery.

OBJECTIVE: To determine treatment outcome after surgical resection for progressive brain metastases after gamma knife radiosurgery (GKR) and to explore the role of dynamic contrast agent-enhanced perfusion magnetic resonance imaging (MRI) and proton spectroscopic MRI studies (MRS/P) in predicting pathological findings. METHODS: Between 1997 and 2002, 32 patients underwent surgical resection for suspected progression of brain metastases from a cohort of 245 patients with brain metastases treated with GKR. Postradiosurgery MRI surveillance was performed at 6 and 12 weeks, and then every 12 weeks after GKR. In some cases, additional MRI scanning with spectroscopy or perfusion (MRS/P) was used to aid differentiation of radiation change from tumor progression. The decision to perform neurosurgical resection was based on MRI or clinical evidence of lesion progression among patients with a Karnofsky performance score of 60 or more and absent or stable systemic disease. RESULTS: Thirteen percent (32 out of 245) of patients and 6% (38 out of 611) of lesions required surgical resection after GKR. The median time from GKR to surgical resection was 8.6 months (range, 1.7-27.1 mo). The 6-, 12-, and 24-month actuarial survival from time of GKR was 97, 78, and 47% for the resected patients and 65, 40, and 19% for the nonresected patients (P < 0.0001). The two-year survival rate of patients requiring two resections after GKR was 100% compared with 39% for patients undergoing one resection (P = 0.02). The median survival of resected patients was 27.2 months (range, 7.0-72.5 mo) from the diagnosis of brain metastases, 19.9 months (range, 5.0-60.7 mo) from GKR, and 8.9 months (range, 0.2-53.1 mo) from surgical resection. Tumor was found in 90% of resected specimens and necrosis alone in 10%. MRS/P studies were performed in 15 resected patients. Overall, MRS/P predicted tumor in 11 lesions, confirmed pathologically in nine lesions, and necrosis alone was found in two. The MRS/P predicted necrosis alone in three, whereas pathology revealed viable tumor in two and necrosis in one lesion. CONCLUSION: Surgical intervention of progressive brain metastases after GKR in selected patients leads to a meaningful improvement in survival rates. Further studies are necessary to determine the role of MRS/P in the postradiosurgery surveillance of brain metastases.

Adult↗

PubMed2005

Multiagent chemotherapy and deferred radiotherapy in infants with malignant brain tumors: a report from the Children's Cancer Group.

PURPOSE: To evaluate response rate, event-free survival (EFS), and toxicity of two chemotherapeutic regimens for treatment of children younger than 36 months with malignant brain tumors and to estimate control intervals without irradiation in children with no residual tumor after initial surgery and induction chemotherapy and with delayed irradiation in patients with residual tumor or metastatic disease at diagnosis. PATIENTS AND METHODS: Patients were randomly assigned to one of two regimens of induction chemotherapy (vincristine, cisplatin, cyclophosphamide, and etoposide v vincristine, carboplatin, ifosfamide, and etoposide). Maintenance chemotherapy began after induction in children without progressive disease. Children with no residual tumors after induction therapy and no metastatic disease at diagnosis were not to receive radiation therapy unless their tumors progressed. RESULTS: Two hundred ninety-nine infants were enrolled. Forty-two percent of patients responded to induction chemotherapy. At 5 years from study entry, the EFS rate was 27% +/- 3%, and the survival rate was 43% +/- 3%. There was no significant difference between the two arms in terms of response rate or EFS. For medulloblastoma, supratentorial primitive neuroectodermal tumor, ependymoma, and rhabdoid tumors, 5-year EFS rates were 32% +/- 5%, 17% +/- 6%, and 32% +/- 6%, and 14% +/- 7%, respectively. Fifty-eight percent of patients who were alive 5 years after study entry had not received radiation therapy. CONCLUSION: Intensified induction chemotherapy resulted in a high response rate of malignant brain tumors in infants. Survival was comparable to that of previous studies, and most patients who survived did not receive radiation therapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

Possible association of p53 codon 72 polymorphism with susceptibility to adult and pediatric high-grade astrocytomas.

Polymorphisms in codon 72 of the p53 tumor suppressor gene have been associated with susceptibility to human cancer. We wished to evaluate whether variant allelic forms of the p53 protein were associated with brain tumors. In this study, we scored 135 brain tumor samples (92 adult and 43 pediatric cases consisting of 64 high-grade astrocytomas and 71 non-astrocytomas) for the P53 Arg72Pro polymorphisms. Our data show that the genotype frequencies of P53 Arg72Pro vary not only between patients with brain tumors and controls, but also between different histological subtypes of brain tumors. Specifically, we found (i) that the genotype distributions of the P53 Arg72Pro between all brain tumors and controls were statistically significant (P < 0.001) as well as their variant allele frequencies between cases and controls (P < 0.001); (ii) that there was a significant increase in the Arg/Pro heterozygous genotype among high-grade astrocytomas compared with non-astrocytomas (P = 0.002); and (iii) that there was a significant increase in the Arg/Pro heterozygous genotype among high-grade astrocytomas containing transdominant as well as recessive p53 mutations compared with controls (P = 0.002). Our results suggest a possible association between P53 Arg72Pro polymorphisms and susceptibility to brain tumors, particularly high-grade astrocytomas.

Adolescent↗

PubMed2005

Osseous metastasis of pineoblastoma: a case report and review of the literature.

PURPOSE: To review the literature on the occurrence of osseous metastases in recurrent pineoblastoma, and to report upon the feasibility and efficacy of treatment using intensive conventional chemotherapy to achieve a remission, followed by consolidation with marrow ablative chemotherapy and autologous hemopoietic stem cell rescue. PATIENT AND METHODS: An adult with isolated extraneural, osseous and bone marrow metastases from a pineoblastoma, received conventional cyclical chemotherapy, followed by consolidation with marrow ablative chemotherapy (thiotepa, carboplatin and temozolomide) and autologous hemopoietic stem cell rescue. RESULTS: A complete radiographic and histopathologic response was achieved after almost one year of conventional chemotherapy that was tolerated without significant sequelae. Following successful harvesting of peripheral blood stem cells, the patient underwent myeloablative chemotherapy with autologous stem cell rescue, without difficulty in hemopoietic reconstitution and without serious or permanent side effects. CONCLUSIONS: Osseous metastases from pineoblastoma are an extremely rare occurrence. We conclude that conventional chemotherapy can achieve a complete response, and subsequent consolidation with marrow ablative chemotherapy and autologous hemopoietic stem cell rescue is feasible and well tolerated.

Adult↗

PubMed2005

Recurrent central nervous system medulloepithelioma: response and outcome following marrow-ablative chemotherapy with stem cell rescue.

Medulloepithelioma is a rare primitive neuroectodermal tumor of the central nervous system usually developing in childhood, displaying highly malignant behavior, with early progression or recurrence. Once a recurrence develops, death reportedly follows with invariable rapidity. The purpose of this study was to evaluate the efficacy of high-dose, marrow-ablative chemotherapy with autologous hemopoietic stem cell rescue in the treatment of recurrent central nervous system medulloepithelioma. Three young children with recurrent central nervous system medulloepithelioma received high-dose marrow-ablative chemotherapy with thiotepa and etoposide either alone (one patient) or with the addition of carboplatin (two patients). This was followed by irradiation only in one patient. One child with residual radiographic tumor at the time of treatment could be evaluated for response and showed complete resolution of leptomeningeal disease after receiving marrow-ablative chemotherapy. Two children developed tumor recurrence at 2.0 and 5.5 months after receiving marrow-ablative chemotherapy. The third child continues free of tumor beyond 12 years from treatment. The authors' experience with marrow-ablative chemotherapy and autologous hemopoietic stem cell rescue suggests that this treatment strategy might be beneficially incorporated into the initial treatment approach for young children with medulloepithelioma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

Flavopiridol downregulates hypoxia-mediated hypoxia-inducible factor-1alpha expression in human glioma cells by a proteasome-independent pathway: implications for in vivo therapy.

Angiogenesis is a critical step required for sustained tumor growth and tumor progression. The stimulation of endothelial cells by cytokines secreted by tumor cells such as vascular endothelial growth factor (VEGF) induces their proliferation and migration. This is a prominent feature of high-grade gliomas. The secretion of VEGF is greatly upregulated under conditions of hypoxia because of the transcription factor hypoxiainducible factor (HIF)-1alpha, which controls the expression of many genes, allowing rapid adaptation of cells to their hypoxic microenvironment. Flavopiridol, a novel cyclin-dependent kinase inhibitor, has been attributed with antiangiogenic properties in some cancer cell lines by its ability to inhibit VEGF production. Here, we show that flavopiridol treatment of human U87MG and T98G glioma cell lines decreases hypoxia-mediated HIF-1alpha expression, VEGF secretion, and tumor cell migration. These in vitro results correlate with reduced vascularity of intracranial syngeneic GL261 gliomas from animals treated with flavopiridol. In addition, we show that flavopiridol downregulates HIF-1alpha expression in the presence of a proteasome inhibitor, an agent that normally results in the accumulation and overexpression of HIF-1alpha. The potential to downregulate HIF-1alpha expression with flavopiridol treatment in combination with a proteasome inhibitor makes this an extremely attractive anticancer treatment strategy for tumors with high angiogenic activity, such as gliomas.

Animals↗

PubMed2005

Minimally invasive method for murine brain fixation.

Complete brain fixation can be achieved with transthoracic cardiac infusion without thoracotomy. Light and electron microscopy tissue sections reveal preservation of cytoplasmic and nuclear structure at all magnification levels. Punched samples were obtained from the fixed tissue specimens in precisely localized areas for study using electron microscopy. This perfusion fixation technique provides both faster tissue harvesting capability and higher quality tissue preservation, without the artifacts of brain swelling and ventricular dilation observed in direct cardiac perfusion. Acute, discrete change in brain tissue can be studied.

Animals↗

PubMed2004

Feasibility and response to induction chemotherapy intensified with high-dose methotrexate for young children with newly diagnosed high-risk disseminated medulloblastoma.

PURPOSE: To evaluate the feasibility of and response rate to an intensified induction chemotherapy regimen for young children with newly diagnosed high-risk or disseminated medulloblastomas. PATIENTS AND METHODS: From January 1997 to March 2003, 21 patients with high-risk or disseminated medulloblastoma were enrolled. After maximal surgical resection, patients were treated with five cycles of vincristine (0.05 mg/kg/wk x three doses per cycle for three cycles), cisplatin (3.5 mg/kg per cycle), etoposide (4 mg/kg/d x 2 days per cycle), cyclophosphamide (65 mg/kg/d x 2 days per cycle) with mesna, and methotrexate (400 mg/kg per cycle) with leucovorin rescue. Following induction chemotherapy, eligible patients underwent a single myeloablative chemotherapy cycle with autologous stem-cell rescue. RESULTS: Significant toxicities of this intensified regimen, including gastrointestinal and infectious toxicities, are described. Among the 21 patients enrolled, there were 17 complete responses (81%), two partial responses, one stable disease, and one progressive disease. The 3-year event-free survival and overall survival are 49% (95% CI, 27% to 72%) and 60% (95% CI, 36% to 84%), respectively. CONCLUSION: This intensified induction chemotherapy regimen is feasible and tolerable. With the majority of patients with disseminated medulloblastoma having M2 or M3 disease at diagnosis, the encouraging high response rate of this intensified induction regimen suggests that such an addition of methotrexate should be explored in future studies.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2004

Thiotepa-based high-dose chemotherapy with autologous stem-cell rescue in patients with recurrent or progressive CNS germ cell tumors.

PURPOSE: To evaluate the efficacy and toxicity of high-dose chemotherapy (HDC) followed by autologous stem-cell rescue (ASCR) in patients with relapsed or progressive CNS germ cell tumors (GCTs). PATIENTS AND METHODS: Twenty-one patients with CNS GCTs who experienced relapse or progression despite having received initial chemotherapy and/or radiotherapy were treated with thiotepa-based HDC regimens followed by ASCR. RESULTS: Estimated overall survival (OS) and event-free survival (EFS) rates for the entire group 4 years after HDC were 57% +/- 12% and 52% +/- 14%, respectively. Seven of nine (78%) patients with germinoma survived disease-free after HDC with a median survival of 48 months. One patient died as a result of progressive disease (PD) 39 months after HDC, and another died as a result of pulmonary fibrosis unrelated to HDC 78 months after ASCR without assessable disease. However, only four of 12 patients (33%) with nongerminomatous germ cell tumors (NGGCTs) survived without evidence of disease, with a median survival of 35 months. Eight patients with NGGCTs died as a result of PD, with a median survival of 4 months after HDC (range, 2 to 17 months). Patients with germinoma fared better than those with NGGCTs (P =.016 and.014 for OS and EFS, respectively). Patients with complete response to HDC also had significantly better outcome (P <.001 for OS and EFS) compared with patients with only a partial response or stable disease. There were no toxic deaths because of HDC. CONCLUSION: Dose escalation of chemotherapy followed by ASCR is effective therapy for patients with recurrent CNS germinomas and might be effective in patients with recurrent NGGCTs with a low tumor burden.

Adolescent↗

PubMed2004

Invariant natural killer T cells are preserved in patients with glioma and exhibit antitumor lytic activity following dendritic cell-mediated expansion.

Brain tumors carry a poor prognosis, and newer approaches to their therapy are urgently needed. Natural killer T (NKT) cells are distinct innate lymphocytes with antitumor potentials. Defects in NKT cell function have been observed in patients with other forms of cancer. Here we show that both the frequency and interferon-gamma-producing function of NKT cells are well preserved in adult patients with glioma (n=9) and comparable to findings in healthy controls (n=9). These cells can be readily expanded in culture using autologous mature dendritic cells loaded with the NKT ligand, alpha-galactosyl ceramide. The expanded NKT cells from glioma patients are functional and, importantly, kill glioma cells in a ligand- and CD1d-dependent manner. Expression of CD1d is detected both on primary glioma cells as well as endothelial cells in infiltrating new blood vessels by immunohistochemistry of glioma tissue sections. These data suggest that targeting NKT cells may provide a novel strategy for immunotherapy of glioma.

Adult↗

PubMed2004

Flavopiridol inhibits the growth of GL261 gliomas in vivo: implications for malignant glioma therapy.

The mechanism of action of many chemotherapeutic agents targets the cell cycle. Recently, we demonstrated cytotoxic and other anti-tumor effects of flavopiridol, the first synthetic cyclin dependent kinase (CDK) inhibitor to enter clinical trials, on the murine GL261 glioma cell line in vitro (Newcomb et al., Cell Cycle 2003; 2:243). Given that flavopiridol has demonstrated anti-tumor activity in several human xenograft models, we wanted to evaluate it for anti-glioma activity in vivo in our established subcutaneous and intracranial GL261 experimental tumor models. In particular, the intracranial animal model recapitulates many of the histopathological and biological features of human high-grade glioma including both necrosis with pseudopalisading and invasion of the brain adjacent to tumor. Here we tested the activity of flavopiridol against tumors formed by GL261 cells, first as subcutaneous implants, and then in the intracranial model. We demonstrate efficacy of flavopiridol as a single modality treatment in delaying tumor growth in both animal models. We hypothesize that flavopiridol treatment induced tumor growth delay by two possible mechanisms involving growth arrest combined with recruitment of tumor cells to S-phase. Based on our findings, flavopiridol should be considered as a treatment approach for patients with high-grade glioma.

Animals↗

PubMed2003

Expression of p27KIP1 in human gliomas: relationship between tumor grade, proliferation index, and patient survival.

Numerous studies examining the prognostic significance of p27KIP1 expression in human cancer have shown that decreased expression often is an independent prognostic factor associated with worse survival. However, the prognostic value of p27KIP1 expression in gliomas is less well established. To further address this issue, we evaluated the relationship between p27KIP1 protein expression in a series of 50 astrocytomas with clinicopathologic parameters including age, tumor grade, MIB-1 proliferation index, and patient survival using both Western blot analysis and immunohistochemistry. The level of p27KIP1 protein expression in 9 nonneoplastic brain tissue specimens served as a control. Sixteen high-grade astrocytomas were analyzed by Western blot, and 26 high-grade astrocytomas were analyzed by immunohistochemistry for levels of p27KIP1 protein expression. Regardless of the technique used to measure p27KIP1, approximately 50% of the high-grade tumors were low expressors and the other 50% were high expressors. Thus, expression of p27KIP1 was independent of tumor grade. Loss of p27KIP1 expression is often associated with an increase in proliferative activity. We measured the rate of tumor cell proliferation using MIB-1 immunostaining in 16 high-grade astrocytomas to determine whether there was an inverse correlation between p27KIP1 expression and proliferation. No correlation between p27KIP1 expression and MIB-1 labeling index or patient survival was found. Using immunohistochemistry, we noted that the staining pattern of p27KIP1 in glioblastomas was mainly in the pseudopalisading cells that outline areas of necrosis. Because p27KIP1 can be up-regulated by hypoxia, this staining pattern would be consistent with our observation that hypoxia-inducible factor 1alpha is expressed primarily in pseudopalisading tumor cells around necrotic zones. It has been shown that a high level of p27KIP1 prevents apoptosis in hypoxic cells. Thus, maintenance of high levels of p27KIP1 in gliomas could result from the hypoxic microenvironment present within the tumor. No correlation was found between p27KIP1 expression and any of the clinicopathologic parameters tested, including patient age and tumor grade, the 2 strongest predictors of survival among glioma patients.

Adolescent↗

PubMed2003

Temozolomide is active in childhood, progressive, unresectable, low-grade gliomas.

PURPOSE: To assess the activity and tolerability of temozolomide in children with progressive low-grade gliomas (LGGs). PATIENTS AND METHODS: The authors reviewed the records of 13 children (6 months to 19 years old) with progressive LGGs and magnetic resonance imaging evidence of unresectable tumors who were treated with temozolomide at the authors' institution since 1999. RESULTS: Four patients received a 5-day regimen of temozolomide (150 mg/m2 per day) repeated every 28 days, and nine patients received a 42-day regimen (75 mg/m2 per day) repeated every 56 days. Three patients demonstrated partial responses to temozolomide, with a median time to maximal response of 5 months (range 4-12 months), and one had a minor response at 9 months. Four patients developed progression while on temozolomide, with a median time to progression of 7 months (range 1-12 months). Five patients had disease stabilization. Among the five patients with prior chemotherapy and/or radiation therapy, temozolomide was associated with disease stabilization in three and tumor response in one. In the three patients with neurofibromatosis type 1, two patients experienced tumor responses and one disease stabilization. Thrombocytopenia, nausea, emesis, and fatigue were the most common toxicities. Four patients discontinued therapy because of the side effects. CONCLUSIONS: Temozolomide is active in children with LGGs. It is effective in previously treated patients and in patients with neurofibromatosis type 1. The 42-day regimen appears less toxic than the 5-day regimen. Any impact on survival for these patients remains to be demonstrated.

Adolescent↗

PubMed2003

Green fluorescent protein immunohistochemistry as a novel experimental tool for the detection of glioma cell invasion in vivo.

In vivo animal models of primary brain tumors are necessary to advance knowledge related to the complex interactions between glioma cells and the adjacent brain. A cardinal feature of glioma growth, and a major reason why neurosurgical and adjunctive therapies ultimately fail in most patients is their invasive properties. We have adapted a previously described animal model developed by one of us to give better histological detail while preserving the identification of single infiltrating glioma cells. GL261 glioma cells were first transfected with the plasmid encoding green fluorescent protein (GFP) and then implanted into the brains of syngeneic C57BL/6 mice. Identification of GFP-positive tumor cells in paraffin sections of the brains of tumor-bearing animals utilized an antibody for conventional immunoperoxidase immunohistochemistry. This method is a more powerful technique compared with the prior use of frozen sections and fluorescence microscopy to identify GFP-tagged tumor cells. We find that this new method provides improved morphology and proves to be a sensitive and reliable system for detection of invading glioma cells. Using this methodology with other advanced technologies (eg, laser capture microdissection) holds out the promise of helping to elucidate the molecular mechanisms of glioma cell infiltration and invasion into the surrounding brain.

Animals↗

PubMed2003

Epithelioid ependymoma: a new variant of ependymoma: report of three cases.

OBJECTIVE: To describe the pathological features of three very similar and unusual primary central nervous system tumors that are not readily recognized as conventional ependymomas but which, by ultrastructural examination, have an ependymomatous character. METHODS: Three distinctive tumors were found in a review of our files for cases of ependymoma. In each case, hematoxylin and eosin-stained sections were reviewed, and immunostains for epithelial membrane antigen, cytokeratin, vimentin, and glial fibrillary acidic protein were performed on formalin-fixed, paraffin-embedded sections. Electron microscopy was performed in each case. RESULTS: The tumors had a diffuse myxoid background, often containing tightly clustered cells that mimicked multinucleated giant cells, but lacking perivascular pseudorosettes or central lumen rosettes. Glial fibrillary acidic protein and vimentin immunostains did not reveal perivascular processes. Epithelial membrane antigen immunostains showed a dot-like cytoplasmic immunoreactivity in some cell clusters in two of the three cases. Cytokeratin was negative in all three cases. However, ultrastructurally, the cells of each tumor had extensive surface microvilli; the giant cell-like clusters had cells with extensive close appositions, some junctions, and, in two cases, lumina with microvilli. Two of the patients were adults (both with temporal lobe tumors), and one patient was 13 years old and had a cervical spinal cord intramedullary tumor. Each tumor was sharply circumscribed from adjacent central nervous system tissue but was not encapsulated. One of the cases in an adult was mitotically highly active; this tumor recurred locally 4 years after initial gross total excision. CONCLUSION: These tumors are unusual variants of ependymoma. This pattern of ependymoma is sufficiently distinctive to be recognized in hematoxylin and eosin stains once the architecture of the epithelioid clusters is appreciated.

Adolescent↗

PubMed2003

Flavopiridol induces apoptosis in glioma cell lines independent of retinoblastoma and p53 tumor suppressor pathway alterations by a caspase-independent pathway.

Flavopiridol is a synthetic flavone, which inhibits growth in vitro and in vivo of several solid malignancies such as renal, prostate, and colon cancers. It is a potent cyclin-dependent kinase inhibitor presently in clinical trials. In this study, we examined the effect of flavopiridol on a panel of glioma cell lines having different genetic profiles: five of six have codeletion of p16(INK4a) and p14(ARF); three of six have p53 mutations; and one of six shows overexpression of mouse double minute-2 (MDM2) protein. Independent of retinoblastoma and p53 tumor suppressor pathway alterations, flavopiridol induced apoptosis in all cell lines but through a caspase-independent mechanism. No cleavage products for caspase 3 or its substrate poly(ADP-ribose) polymerase or caspase 8 were detected. The pan-caspase inhibitor Z-VAD-fmk did not inhibit flavopiridol-induced apoptosis. Mitochondrial damage measured by cytochrome c release and transmission electron microscopy was not observed in drug-treated glioma cells. In contrast, flavopiridol treatment induced translocation of apoptosis-inducing factor from the mitochondria to the nucleus. The proteins cyclin D(1) and MDM2 involved in the regulation of retinoblastoma and p53 activity, respectively, were down-regulated early after flavopiridol treatment. Given that MDM2 protein can confer oncogenic properties under certain circumstances, loss of MDM2 expression in tumor cells could promote increased chemosensitivity. After drug treatment, a low Bcl-2/Bax ratio was observed, a condition that may favor apoptosis. Taken together, the data indicate that flavopiridol has activity against glioma cell lines in vitro and should be considered for clinical development in the treatment of glioblastoma multiforme.

Antineoplastic Agents↗