Takakazu Yokoyama

Promoter hypermethylation of the DNA repair gene O6-methylguanine-DNA methyltransferase is an independent predictor of shortened progression free survival in patients with low-grade diffuse astrocytomas

The O6‐methylguanine‐DNA methyltransferase (MGMT) plays a major role in repairing DNA damage from alkylating agents. In several human neoplasms including low‐grade diffuse astrocytomas, promoter hypermethylation of MGMT has been shown to correlate with an increased frequency of p53 mutation. In the present study, we analyzed MGMT promoter methylation by the methylation‐specific PCR in 49 newly diagnosed WHO grade II astrocytomas and evaluated its clinical usefulness. MGMT promoter methylation was found in 21 (43%) of the 49 tumors. A tight correlation existed between MGMT methylation and p53 protein accumulation (P=0.0424). The presence of MGMT methylation was significantly associated with a shorter progression free survival (PFS) on both univariate analysis (P=0.0014) and multivariate analysis (P=0.0081). It was a more powerful determinant of the PFS than age, sex, performance status, proliferative activity, or p53 expression, and was independent of the extent of surgery. In terms of the overall survival, MGMT methylation demonstrated a prognostic utility in the univariate analysis but not in the multivariate analysis. The present findings indicate that aberrant methylation of the MGMT promoter independently augurs for an unfavorable clinical course in patients with low‐grade diffuse astrocytomas. Since the presence of MGMT methylation is expected to predict an increased sensitivity to alkylating chemotherapeutic agents, earlier chemotherapy could serve to improve an unfavorable natural history in tumors with MGMT methylation.

Telomerase activity in pituitary adenomas: significance of telomerase expression in predicting pituitary adenoma recurrence

Clinical and histopathological evaluations are inadequate for assessing biological aggressiveness and regrowth potential in benign pituitary adenomas. To develop reliable and prognostically informative means of predicting behavior remains an intractable problem. Telomerase, a reverse transcriptase that extends telomere length, may facilitate tumorigenesis and tumor immortality. In the present study, we investigated the telomerase activity of pituitary adenomas, and attempted to assess the value of telomerase expression for predicting their clinical course. In total, 31 (30 patients) benign pituitary adenoma samples including 8 recurrent adenomas were studied. Telomerase expression was evaluated by polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay and telomerase activity levels were quantitated by improved PCR enzyme-linked immunosorbent assay (ELISA). The data were analyzed in relation to clinical course which was reviewed at 4–5.5 years (median follow-up time, 52.5 months) after surgery. The relative values of the telomerase expression for predicting the clinical course were compared with the MIB-1 antigen-based proliferative cell index (PCI) and p53 immunoreactivity which have recently been suggested to correlate with aggressive behavior in pituitary adenomas. Overall, telomerase expression was detected in 13% of the adenomas (4 tumor tissues, 3 patients). These adenomas comprised large, invasive, and functioning adenomas. The number of telomerase-positive adenomas was small; however, the PCI was higher in cases with telomerase expression (4 tumor tissues; mean, 4.2 ± 2.4%) than in those without it (27 tumor tissues; 1.4 ± 1.3%) (p = 0.01). One tumor with detectable telomerase expression, which did not undergo additional pharmacological or radiotherapeutic intervention after first surgery, recurred rapidly despite gross total surgical resection, although the PCI of both the primary and recurrent adenomas was not high. Detection of telomerase expression may represent an additional useful means of identifying aggressive behavior, complementing the histopathological evaluation of benign-appearing pituitary adenomas.

Long-term remission of primary central nervous system lymphoma by intensified methotrexate chemotherapy.

High-dose (1–3.5 g/m2) methotrexate (MTX) followed by whole-brain radiation therapy (WBRT) has consistently improved length of survival in primary central nervous system lymphoma (PCNSL), but the prognosis remains dismal. To optimize and enhance the dose intensity of MTX, we applied MTX at 8 g/m2 to 20 patients with PCNSL. In an effort to lower the risk of neurotoxic treatment sequelae, the WBRT dose was reduced to 30 Gy in cases of complete remission after MTX therapy. Further, omission of WBRT and administration of stereotactic radiotherapy (SRT) were undertaken in 3 older patients. The overall response rate to the MTX therapy was 83%. The median progression free survival (PFS) was 54 months with a median overall survival (OS) of 57 months. Achieving a complete response after MTX therapy was significantly associated with a longer PFS. Late neurotoxicity was encountered in 4 (50%) of 8 patients who were aged 60 years or older and received WBRT, but in none of 12 patients who were aged less than 60 years or avoided WBRT. All older patients who underwent SRT sustained complete remission without a dementing disease. Intensifying the MTX dosage to 8 g/m2 appears more promising in comparison to results reported with MTX doses of 1–3.5 g/m2. In younger patients, the establishment of complete remission by intensified MTX therapy and subsequent WBRT with a relatively lower dose could promise durable tumor remission with an acceptable neurotoxicity. In older patients, WBRT should be avoided to sustain a meaningful survival, and SRT may provide a valid strategy in terms of enhancing local disease control without undue risk.

Apoplexy accompanying pituitary adenoma as a complication of preoperative anterior pituitary function tests

SummaryPituitary apoplexy occurs as a very rare complication of the pituitary function test. We have experienced two cases of pituitary apoplexy following anterior pituitary function tests for preoperative assessment: a triple bolus test and a TRH test. To elucidate such a rare complication, we outline our two cases and review 28 cases from the literature. The clinical characteristics, etiology, pathophysiology, and diagnostic and therapeutic implications are also discussed. The combined data suggest that pituitary function tests have the potential to precipitate pituitary apoplexy, and its manifestations range from a clinically benign event to a catastrophic presentation with permanent neurological deficits or even death, although most patients may fortunately have a good outcome. We suggest that the pituitary function test should not be done as a routine test, and when such a test is planned, the patient should be observed with caution for any symptomatic changes for at least 2 hours following the test for appropriate treatment. Further, MRI, especially enhanced studies, may provide an earlier diagnosis of the pituitary apoplexy since CT scan images often fail to demonstrate either density changes or obvious enlargement of the pituitary adenoma at the acute stage.

Therapeutic Implications of Interferon Regulatory Factor (IRF)-1 and IRF-2 in Diffusely Infiltrating Astrocytomas (DIA): Response to Interferon (IFN)-β in Glioblastoma Cells and Prognostic Value for DIA

SummaryThe precise mechanisms governing the direct effect of IFN-β, including apoptosis induction, are not yet fully understood. To gain a better insight into these mechanisms, we investigated the signaling pathways focusing particularly on interferon regulatory factor 1 (IRF-1) and IRF-2 in glioblastoma cell lines. Furthermore, we attempted to determine whether or not IRF-1 and IRF-2 act as additional prognostic indicators in diffusely infiltrating astrocytomas (DIA). We first assessed the cytotoxic effects of IFN-β based on a cell growth study and modified MTT assay, and then quantified the apoptosis using a sandwich enzyme immunoassay following IFN-β treatment in the cell lines, U-87MG, T98G, and A-172. Subsequently, we carried out an analysis of apoptosis-related molecules as evaluated by densitometric analysis of Western blots, focusing on IRF-1 and IRF-2, and two major initiator caspases, caspase-8 and caspase-9. Furthermore, we assessed the expression of type I IFN receptor, IRF-1, and IRF-2 using immunohistochemical techniques in 63 DIA (15 of WHO grade II, 18 of grade III, and 30 of grade IV), and analyzed their impact on prognosis. An increase in apoptosis was apparent after 48 h of IFN-β treatment (1 × 104 IU/ml) in T98G but not in U-87MG or A-172. IFN-β treatment for 6 h significantly enhanced the expression of IRF-1 in all three cell lines. However, an enhanced expression of IRF-2 was observed only in the not-most-sensitive, non-apoptosis-induced U-87MG and A-172. While minimal processing of caspase-8 was noted in the three cell lines throughout the experiment, caspase-9 activation was observed in the apoptosis-detected T98G after 48 h of treatment, as indicated by a 1.33-fold increase (P=0.037). On the other hand, the IRF-1 LI and IRF-1/IRF-2 LI ratio were greater in low-grade DAI, and were negatively correlated with the histopathological grade in DIA (P=0.017 and P=0.001, respectively). Furthermore, the IRF-1/IRF-2 LI ratio was negatively correlated with the MIB-1 LI in DIA (P=0.004), and represented an independent and most powerful determinant of overall survival compared to other conventional prognostic factors (P=0.018). However, the relation was not statistically significant when only patients with high-grade DIA were assessed. Our findings suggest that up-regulation of IRF-1 and IRF-2 might be an important determinant of susceptibility to IFN-β mediated cytotoxicity including apoptosis. Furthermore, the IRF-1/IRF-2 LI ratio may reflect the proliferative state of DIA and constitute an important prognostic marker in DIA. Thus, IRF-1 and IRF-2 could represent one of the therapeutic target sites for the regulation of cell growth in DIA.

Treatment of Low-grade Diffuse Astrocytomas by Surgery and Human Fibroblast Interferon without Radiation Therapy

Low-grade diffuse astrocytomas are slowly growing tumors with a relatively long overall survival. However, a substantial proportion undergoes dedifferentiation to a more malignant phenotype. Considerable controversy exists as to the best therapeutic management for patients with such tumors. Over the past decade, we have applied human fibroblast interferon (HFIF) therapy without radiation therapy to low-grade astrocytomas. We investigated 28 patients with WHO grade II astrocytomas of the cerebral hemispheres treated by surgery plus HFIF therapy. The overall response rate to the HFIF therapy was 36%. All side-effects of HFIF were transient, tolerable and manageable. The 5-year progression free survival and overall survival probabilities were 65% and 96%, respectively. Although our data from small cohort of patients may have modest value, our results suggest that HFIF may be useful in treating low-grade diffuse astrocytomas.

Pleomorphic granular cell astrocytoma in the pineal gland: case report.

Pleomorphic granular cell astrocytoma in the pineal region is exceedingly rare, and its clinicopathological features are distinctive. A 67‐year‐old woman was admitted with a staggering gait. Magnetic resonance imaging revealed a mass lesion at the pineal gland accompanied by obstructive hydrocephalus. Following surgery, pathological examinations demonstrated a pleomorphic granular cell astrocytoma. The patient has been free from recurrence for 24 months after surgery without adjuvant therapy. The specimen exhibited nuclear and cytoplasmic pleomorphism. The nuclei varied in size, shape and coarseness. Variability was also observed in the eosinophilic granular bodies, Rosenthal fibers and spindle‐shaped tumor cells. GFAP, S‐100 and vimentin were immunohistochemically positive. Reticulin network was absent between the tumor cells, and granular cells with ballooned cytoplasm showing positive staining for PAS. Pleomorphic granular cell astrocytoma is believed to be a form of astrocytoma originating from the pineal gland. Its clinicopathological features resemble those of pleomorphic xanthoastrocytoma. However, it can be differentiated from the latter by the absence of reticulin fibers, absence of basement membrane between adjacent cells, and presence of large numbers of mitochondria.

Aberrant TP53 protein accumulation in the neuronal component of ganglioglioma

Gangliogliomas are characterized by their different phenotypic composition of ganglion cells and glial cells. In contrast to the glial cells that are capable of mitotic activity, the ganglion cells are generally considered to lack a neoplastic nature. The authors report here the first unequivocal case of a ganglioglioma harboring aberrant TP53 product that was expressed predominantly in the neuronal component. GeneChip TP53 assay revealed a point mutation resulting in an exchange of amino acid. This case suggests that ganglion cells can participate in the neoplastic process of gangliogliomas.