Weak cation magnetic separation technology and MALDI-TOF-MS in screening serum protein markers in primary type I osteoporosis.

We investigated weak cation magnetic separation technology and matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) in screening serum protein markers of primary type I osteoporosis. We selected 16 postmenopausal women with osteoporosis and nine postmenopausal women as controls to find a new method for screening biomarkers and establishing a diagnostic model for primary type I osteoporosis. Serum samples were obtained from controls and patients. Serum protein was extracted with the WCX protein chip system; protein fingerprints were examined using MALDI-TOF-MS. The preprocessed and model construction data were handled by the ProteinChip system. The diagnostic models were established using a genetic arithmetic model combined with a support vector machine (SVM). The SVM model with the highest Youden index was selected. Combinations with the highest accuracy in distinguishing different groups of data were selected as potential biomarkers. From the two groups of serum proteins, 123 cumulative MS protein peaks were selected. Significant intensity differences in the protein peaks of 16 postmenopausal women with osteoporosis were screened. The difference in Youden index between the four groups of protein peaks showed that the highest peaks had mass-to-charge ratios of 8909.047, 8690.658, 13745.48, and 15114.52. A diagnosis model was established with these four markers as the candidates, and the model specificity and sensitivity were found to be 100%. Two groups of specimens in the SVM results on the scatterplot were distinguishable. We established a diagnosis model, and provided a new serological method for screening and diagnosis of osteoporosis with high sensitivity and specificity.

Fixed-dose pegfilgrastim is safe and allows neutrophil recovery in patients with non-Hodgkin's lymphoma.

Twenty-nine patients with non-Hodgkin's lymphoma received a single subcutaneous injection of 6 mg pegfilgrastim approximately 24 h after the start of CHOP chemotherapy. The safety of pegfilgrastim in this patient population was determined by reports of adverse events. The pharmacokinetics of pegfilgrastim were characterized and the duration of grade 4 neutropenia, time to absolute neutrophil count (ANC) recovery to > or = 2.0 x 10(9)/l, neutrophil nadir, and incidence of febrile neutropenia were determined in the first 21-day chemotherapy cycle. The incidence of grade 4 neutropenia in cycle 1 was 43% with a mean (SD) duration of grade 4 neutropenia value of 1.0 (1.4) day. No apparent relationship between the duration of grade 4 neutropenia and body weight was observed. The median [quartiles] time to ANC recovery was 10 [9, 11] days. The incidence of febrile neutropenia was 11%. No unexpected adverse events were reported and no patient developed antibodies to pegfilgrastim. Serum concentration of pegfilgrastim reached a maximum (median [quartiles]) of 128 [58, 159] ng/ml at approximately 24 h after administration, and was followed by a second smaller peak (median [quartiles]) of 10.6 [3.0, 20.5] ng/ml at the time of the neutrophil nadir. After the second peak, concentration of pegfilgrastim declined linearly with a median terminal half-life of approximately 42 h.

Randomized, multicenter, open-label study of pegfilgrastim compared with daily filgrastim after chemotherapy for lymphoma.

PURPOSE: The primary objective was to assess the duration of grade 4 neutropenia (neutrophil count < 0.5 x 10(9)/L) after one cycle of chemotherapy with etoposide, methylprednisolone, cisplatin, and cytarabine in patients randomly assigned to receive one dose of pegfilgrastim or daily filgrastim after chemotherapy. Febrile neutropenia, neutrophil profiles, time to neutrophil recovery, pharmacokinetics, and safety were also assessed. PATIENTS AND METHODS: An open-label, randomized, phase II study was designed to compare the effects of a single subcutaneous injection of pegfilgrastim (sustained-duration filgrastim) 100 micro g/kg per chemotherapy cycle (n = 33) with daily subcutaneous injections of filgrastim 5 micro g/kg (n = 33) in patients receiving salvage chemotherapy for relapsed or refractory Hodgkin's or non-Hodgkin's lymphoma. RESULTS: The incidence of grade 4 neutropenia in the pegfilgrastim and filgrastim groups was 69% and 68%, respectively. In addition, the mean duration of grade 4 neutropenia was similar in both groups (2.8 and 2.4 days, respectively). The results for the two groups were also not significantly different for febrile neutropenia, neutrophil profile, time to neutrophil recovery, or toxicity profile. A single subcutaneous injection of pegfilgrastim 100 micro g/kg produced a sustained serum concentration relative to daily subcutaneous injections of filgrastim. Filgrastim-treated patients received a median of 11 injections per cycle. CONCLUSION: Pegfilgrastim was safe and well tolerated in this patient population. A single injection of pegfilgrastim per chemotherapy cycle provided neutrophil support with safety and efficacy similar to that provided by daily injections of filgrastim. Once-per-cycle administration of pegfilgrastim simplifies the management of neutropenia and may have important clinical benefits for patients and healthcare providers.

A randomized double-blind multicenter phase III study of fixed-dose single-administration pegfilgrastim versus daily filgrastim in patients receiving myelosuppressive chemotherapy.

BACKGROUND: We evaluated the efficacy of a single fixed 6 mg dose of pegfilgrastim (a pegylated version of filgrastim) per cycle of chemotherapy, compared with daily administration of filgrastim, in the provision of neutrophil support. PATIENTS AND METHODS: Patients (n = 157) were randomized to receive either a single 6 mg subcutaneous (s.c.) injection of pegfilgrastim or daily 5 mg/kg s.c. injections of filgrastim, after doxorubicin and docetaxel chemotherapy (60 mg/m(2) and 75 mg/m(2), respectively). Duration of grade 4 neutropenia, depth of neutrophil nadir, incidence of febrile neutropenia, time to neutrophil recovery and safety information were recorded. RESULTS: A single 6 mg injection of pegfilgrastim was as effective as daily injections of filgrastim for all efficacy measures for all cycles. The mean duration of grade 4 neutropenia in cycle 1 was 1.8 and 1.6 days for the pegfilgrastim and filgrastim groups, respectively. Results for all efficacy end points in cycles 2-4 were consistent with the results from cycle 1. A trend towards a lower incidence of febrile neutropenia was noted across all cycles with pegfilgrastim compared with filgrastim (13% versus 20%, respectively). A single fixed dose of pegfilgrastim was as safe and well tolerated as standard daily filgrastim. CONCLUSIONS: A single fixed dose of pegfilgrastim administered once per cycle of chemotherapy was comparable to multiple daily injections of filgrastim in safely providing neutrophil support during myelosuppressive chemotherapy. Pegfilgrastim may have utility in other clinical settings of neutropenia.

Comparable efficacy and safety profiles of once-per-cycle pegfilgrastim and daily injection filgrastim in chemotherapy-induced neutropenia: a multicenter dose-finding study in women with breast cancer.

BACKGROUND: Neutropenia is common in patients receiving myelotoxic chemotherapy. Pegfilgrastim, a sustained-duration filgrastim is a once-per-cycle therapy for prophylactic neutrophil support. PATIENTS AND METHODS: Women, treated with four cycles of doxorubicin/docetaxel chemotherapy every 21 days, received pegfilgrastim or filgrastim 24 h after chemotherapy as a single subcutaneous injection per chemotherapy cycle (pegfilgrastim 30, 60 or 100 microg/kg) or daily subcutaneous injections (filgrastim 5 microg/kg/day). Safety, efficacy and pharmacokinetics were analyzed. RESULTS: The incidence of grade 4 neutropenia in cycle 1 was 95, 90 and 74%, in patients who received pegfilgrastim 30, 60 and 100 microg/kg, respectively, and 76% in patients who received filgrastim. Mean duration of grade 4 neutropenia in cycle 1 was 2.7,2 and 1.3 days for doses of pegfilgrastim, and 1.6 days for filgrastim. The pharmacokinetics of pegfilgrastim were non-linear and dependent on both dose and neutrophil count. Pegfilgrastim serum concentration was sustained until the neutrophil nadir occurred then declined rapidly as neutrophils started to recover, consistent with a self-regulating neutrophil-mediated clearance mechanism. The safety profiles of pegfilgrastim and filgrastim were similar. CONCLUSIONS: A single subcutaneous injection of pegfilgrastim 100 microg/kg provided neutrophil support and a safety profile comparable to daily subcutaneous injections of filgrastim during multiple chemotherapy cycles.

Blinded, randomized, multicenter study to evaluate single administration pegfilgrastim once per cycle versus daily filgrastim as an adjunct to chemotherapy in patients with high-risk stage II or stage III/IV breast cancer.

PURPOSE: This multicenter, randomized, double-blind, active-control study was designed to determine whether a single subcutaneous injection of pegfilgrastim (SD/01, sustained-duration filgrastim; 100 microg/kg) is as safe and effective as daily filgrastim (5 microg/kg/d) for reducing neutropenia in patients who received four cycles of myelosuppressive chemotherapy. PATIENTS AND METHODS: Sixty-two centers enrolled 310 patients who received chemotherapy with docetaxel 75 mg/m(2) and doxorubicin 60 mg/m(2) on day 1 of each cycle for a maximum of four cycles. Patients were randomized to receive on day 2 either a single subcutaneous injection of pegfilgrastim 100 microg/kg per chemotherapy cycle (154 patients) or daily subcutaneous injections of filgrastim 5 microg/kg/d (156 patients). Absolute neutrophil count (ANC), duration of grade 4 neutropenia, and safety parameters were monitored. RESULTS: One dose of pegfilgrastim per chemotherapy cycle was comparable to daily subcutaneous injections of filgrastim with regard to all efficacy end points, including the duration of severe neutropenia and the depth of ANC nadir in all cycles. Febrile neutropenia across all cycles occurred less often in patients who received pegfilgrastim. The difference in the mean duration of severe neutropenia between the pegfilgrastim and filgrastim treatment groups was less than 1 day. Pegfilgrastim was safe and well tolerated, and it was similar to filgrastim. Adverse event profiles in the pegfilgrastim and filgrastim groups were similar. CONCLUSION: A single injection of pegfilgrastim 100 microg/kg per cycle was as safe and effective as daily injections of filgrastim 5 microg/kg/d in reducing neutropenia and its complications in patients who received four cycles of doxorubicin 60 mg/m(2) and docetaxel 75 mg/m(2).

Familial neurogenic tumor syndromes.

Cancer caused more than 0.5 million deaths in the United States in 2000. This estimate includes patients who have a genetic predisposition to neoplastic disease, including brain neoplasms. Familial tumor syndromes are important to identify clinically because family members require high degrees of monitoring and genetic counseling. Study of these individuals and families has led to the discovery of genes that are an intrinsic aspect of cell regulation and will continue to be relevant in defining mechanisms of neoplastic development in brain and other tissues.

Ethyl-nitrosourea transformed astrocytes exhibit mitochondrial membrane hyperpolarization and constrained apoptosis.

Recent studies have shown the mitochondria and mitochondrial DNA are altered in gliomas, studied either as primary tissues or in culture. Few studies have been performed which evaluate the mitochondria during the development of glial malignancy. We used an ethyl-nitrosourea (ENU) in vitro model to assess the changes in mitochondrial parameters with progression to astrocyte transformation. When compared to the untreated control cells mitochondrial mass of the ENU treated cells significantly decreased ontologically early with concurrent increase in mitochondrial membrane potential, resulting in hyperpolarization of the mitochondrial membrane. At successive divisions, the degree of spontaneous apoptosis during astrocyte transformation was significantly diminished in the ENU treated cells. With 24 h pre- and co-treatment of ENU cells with citrate, an allosteric inhibitor of phosphofructokinase, the astrocytes still became immortal, but did not manifest any of the mitochondrial changes nor acquire the transformed properties of the ENU treated cells without the inhibition. Indeed, the degree of apoptosis noted in these dually treated cells was increased, associated with a loss of anchorage independence and low density growth. Transformed subclones exposed to citrate after the development of malignant properties also exhibited increased apoptosis, and did not form colonies in low density plating conditions. These results suggest that the development of transformed properties in an ENU model is associated with marked hyperpolarization of mitochondrial membrane potential and diminished spontaneous apoptosis. Exposure to citrate attenuated these mitochondrial changes and in vitro growth properties, with increases in apoptosis. The development of transformed astrocytes involve constraints on apoptosis related to alterations in mitochondrial membrane potential and mass.

2',3'-Dideoxycytidine is a potent inducer of apoptosis in glioblastoma cells.

The effect of 2',3'-dideoxycytidine (ddC) treatment on two human glioblastoma cell lines was characterized. ddC treatment (10 nM-100 microM) of glioblastoma cells was associated with enlargement and shortening of processes within 2-3 days. Assessment of mitochondrial membrane potential showed an early decrease in the number of polarized mitochondria in the glioma cells, at between 16 to 84% of the untreated control. With chronic exposure to varying doses of ddC, the tumor cells underwent apoptosis within 5-32 days. This apoptosis was dramatic, with a complete loss of cell viability in < 6 hours after cells were noted to begin detaching from the tissue culture flask. Supplementation with uridine, pyruvate and glucose could delay cellular death at the lower doses of ddC (10 nM to 15 microM) but not at the higher doses. However, regardless of supplementation, all cells eventually underwent apoptosis. ddC is a potent inducer of apoptosis in human glioblastoma cells. Assessments of efficacy in in vivo models and clinical trials should be performed to determine the value of ddC in the treatment of malignant brain tumors.

Receptor expression, cytogenetic, and molecular analysis of six continuous human glioma cell lines.

Six human glioma cell lines were established from tissues obtained from five patients diagnosed with Kernohan grade IV glioblastoma multiforme and one from a patient with a grade II astrocytoma. One line was from a recurrent patient who had received prior therapy; the other lines were derived from patients at initial diagnosis and/or before cytoreductive therapies other than surgery were given. Considerable variability in phenotypic, karyotypic, and cell surface marker expression was displayed between the six human glioma cell lines. The karyotypes ranged from apparently normal (grade II astrocytoma) to those with complex rearrangements. Trisomy of chromosome 7 was the most common abnormality. The extensive cytogenetic and molecular characterization of these lines may facilitate their utilization in cellular and molecular biologic studies.

Locoregional approaches to therapy with gliomas as the paradigm.

Most malignant gliomas recur locally, despite the fact that these tumors are usually found to be diffusely infiltrating on pathologic studies. Thus, efforts have concentrated on local disease control as an initial step to improve the prognosis of these patients. This review discusses the most recent studies on locoregional approaches in therapy for this poor-prognosis neoplasm. Emphasis is placed on the radiotherapeutic and combined modality (radiotherapy and chemotherapy) approaches reported during the past year.

Mutagenesis, tumorigenicity, and apoptosis: are the mitochondria involved?

Early studies have shown mitochondrially-mediated oxidative phosphorylation is diminished in cancer cells, with glycolysis being the main source of energy production. More recent provocative reports have indicated that the mitochondria may be involved in a host of different aspects of tumorigenesis, including mutagenesis, maintenance of the malignant phenotype, and control of apoptosis. These studies have broadened the possible roles mitochondria may play in malignancy. Further studies to define the importance of mitochondria should revolve around the functional assessment of these changes in vitro and in vivo, and will be interesting for determining their significance in human cancer.

Chemosensitization of glioblastoma cells to bis-dichloroethyl-nitrosourea with tyrphostin AG17.

Recent data have suggested that mitochondria play a supportive role in maintaining the tumorigenic phenotype. Indeed, antimitochondrial agents have been hypothesized to be potential chemosensitizers to human malignancy. We assessed the utility of this approach by characterizing the antimitochondrial activity of 3,5-di-tert-butyl-4-hydroxybenzylidene-malononitrile (AG17), in combination with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in two human glioblastoma cell lines. AG17 (NSC 242557) is a tyrphostin that has been thought to have some antimitochondrial activity, with limited tyrosine kinase antagonism, and was used at noncytotoxic and nongrowth-inhibitory concentrations (0.25 microM). Glioblastoma cells were incubated in AG17, and changes in mitochondrial activity were determined. Tumor cells became auxotrophically dependent on uridine and pyruvate, indicating the lack of a functioning respiratory chain. Despite this, cells continued to exhibit no growth-inhibitory effects. Exposure to AG17 was associated with significant depolarization of the mitochondrial membrane potential and decreases in mitochondrial mass in both glioblastoma cell lines, correlating with the finding of auxotrophic dependence. In contrast, normal human astrocytes treated with the same dose of AG17 did not show changes in growth, mitochondrial membrane potential, or mass. Indeed, auxotrophic dependence on uridine and pyruvate could not be established in these cells. Glioblastoma cells became significantly more responsive to BCNU chemotherapy with AG17 pretreatment; a linear relationship was noted that correlated the number as well as percentage of polarized mitochondria with glioblastoma cell survival at the highest dose of BCNU used (144 microg/ml). Normal human astrocytes did not change with regard to the dose response to BCNU with previous incubation with AG17. No difference was found in the type of cellular death (apoptosis) in either of the glioblastoma cell lines, with BCNU treatment alone, or with the combination AG17 and BCNU, despite the decrease in polarized mitochondria and mitochondrial mass. AG17 has antimitochondrial properties when used at low dose in human glioblastoma, which are relatively specific to tumor cells when compared with normal astrocytes. The use of AG17 as a chemosensitizer, with drugs such as BCNU, offers a new and possibly effective approach to be developed in patients with glial tumors.

Increased sensitivity to cis-diamminedichloroplatinum induced apoptosis with mitochondrial DNA depletion.

Malignant cells harbor mechanisms which allow escape from drug-induced apoptosis, and the drug-resistance phenotype can be significantly associated with resistance to programmed cell death. There is accumulating evidence that mitochondria play a role in the tumorigenic phenotype, including the relative resistance to apoptosis. Whether changes at the mitochondrial level per se, would impact on the relative sensitivity of malignant cells to undergo drug-induced apoptosis, is not know. Accordingly, we determined if depleting mitochondrial DNA (mtDNA) would change the susceptibility of U937 cells to undergo apoptosis. With depletion, increases in sensitivity to cis-diamminedichoroplatinum (cisplatin)-induced apoptosis was observed. This sensitivity could be reverted to the parental phenotype by transforming the depleted cells with normal platelet mitochondria. mRNA expression of BAX, BCL2, MDR1, MRP, ERCC1 and ERCC2, putatively associated with cisplatin resistance to apoptotic death was unchanged. Inhibition of mitochondrial ATP production by oligomycin did not result in a change in ATP levels, indicating energetics were not playing a role in the observed phenotype changes. All U937 cells (with/without mtDNA) continued to respond to cisplatin by an apoptotic death. MtDNA-encoded molecules may be playing a role in the relative sensitivity of cells to undergo a cisplatin-induced apoptotic death, but may not be required for cells to undergo apoptosis per se.

Chemotherapy response criteria in malignant glioma.

No one has ever proven a relationship between the extent of response to chemotherapy in malignant glioma and time to progression or survival. We studied the predictive value of "imaging response" following two courses of nitrosourea-based chemotherapy in 136 patients with recurrent astrocytoma/malignant glioma. We performed image analysis by blinded side-to-side comparison of sequential studies, and categorized response into: partial response (PR) (>50% reduction), minor response (MR) (25-50% reduction), stable disease (SD) (<25% change), progressive disease (PD) (>25% increase). Patients with PR, MR, and SD did not differ with respect to time to progression (TTP) (p > 0.2) or survival (p > 0.2). Median TTP was 27 weeks for SD, 43 weeks for MR, and 30 weeks for PR. Patients with PD had a significantly reduced survival (p < 0.001). Median survival was 21 weeks for PD, 53 weeks for SD, 63 weeks for MR, and 48 weeks for PR. The lack of relationship between response and TTP may be due to early relapses in patients with response, a cytostatic benefit of chemotherapy in some patients who do not have an objective response, or a relatively favorable natural history in some tumors that do not respond to chemotherapy. Our data do not support the validity of current response grading, assessed after two courses of chemotherapy. Further research and validation of response criteria is necessary.

Diminished tumorigenic phenotype after depletion of mitochondrial DNA.

Modulation of tumorigenicity has been considered to be a reflection of the (nuclear) genetic and cellular aberrations present in tumor cells. Recent studies have suggested that cytoplasmic elements can also contribute to the malignant phenotype of cancer, and that mitochondria may be important in this process. We, therefore, undertook a study to evaluate the effects of depletion of functional mitochondria on the tumorigenic phenotype. Brain and breast tumor cells were depleted of mitochondrial DNA [rho(-)] by treatment with ethidium bromide. These rho(-) respiratory-deficient cells showed a distinct change in the tumorigenic phenotype, including loss of ability to grow in an anchorage-independent fashion and, interestingly, a substantial increase in sensitivity to cytotoxic drugs (1,3-bis-chloroethyl-1-nitrosourea and cis-diamminedichloroplatinum(II)). Reversion to the tumorigenic phenotype was accomplished with transfer of normal mitochondria into the diminished tumorigenic rho(-) cells. No changes in expression of the apoptosis genes bcl-2 and bax, nor the drug resistance genes mdr1, mrp, or O6-alkyltransferase was found in any of the cell types (de novo, rho(-), or cybrid). Further, the type of cell death remained the same, i.e., cells with and without mitochondria underwent apoptosis in response to exposure to cytotoxic agents. Our results indicate that mitochondria/mitochondrial DNA play a direct role in modulating aspects of the tumorigenic phenotype, although they are not necessarily a sine qua non for apoptotic cell death. This is particularly interesting because most tumor tissues are more dependent upon glycolysis for energy production, rather than mitochondrially mediated oxidative phosphorylation. Creation of rho(-) cells will be useful to study the mitochondrial processes involved in tumorigenesis.

Effects of hypoxia on drug resistance phenotype and genotype in human glioma cell lines.

Recurrent gliomas are most often treated by chemotherapy. However, these tumors typically acquire resistance to most drugs administered, and patients will usually die of recurrent tumor. Factors which may play a role include overexpression of putative multidrug resistance genes, such as the multidrug resistance gene 1 (MDR1), multidrug resistance associated protein gene (MRP), 06-alkylguanine, DNA alkyltransferase gene (06MT) and excision repair cross complementing gene 1 (ERCC1). Tumor hypoxia has also been shown to be associated with drug resistance in other soft tissue tumors. Since gliomas have regions of diminished oxygenation, and have clinical resistance to chemotherapy, the relationship between phenotypic resistance to chemotherapy after hypoxic exposure and expression of drug resistance genes was investigated in glioma cell lines (U373 MG, PFAT-MT). After a 24 hour exposure to hypoxia, drugs 1, 3-bis, 2-chloroethyl-1-nitrosurea (BCNU) and cis-diammine, dichloroplatinum II (CDDP) were administered, and cell survival was determined. Hypoxic exposure was associated with increased survival of the cell lines after administration of BCNU and CDDP, with resistance to BCNU 15 to 30-fold when compared to cells which did not undergo hypoxic exposure. Both tumor cell lines also showed some degree of resistance to CDDP, although not to the extent of BCNU (2 to 3-fold increased resistance). The expression of the drug resistance genes was found to be unchanged when comparing cells which had undergone hypoxic exposure and those which had not. Thus, hypoxic exposure is associated with substantial drug resistance in brain tumor cell lines. The lack of correlation between the induced phenotype and known drug resistance genes suggests other mechanisms may be acting in these tumors in hypoxic conditions.

Mitochondrial DNA copy number changes in human gliomas.

Gene amplification has been found to be biologically important in cancer. We report a complementary DNA sequence obtained using a subtractive hybridization approach which is frequently and highly amplified in human gliomas. 39/45 (87%) glial tumor specimens (of pathologically low and high grade) revealed increases in copy number of this clone from 5- to 25- fold; erb-b amplification was found in 8/45 (18%). This clone revealed homology to non-continuous mitochondrial DNA positions 1679-1948 and 2017-2057, with the interspersed sequences deleted. A non-mitochondrial genomic addition of 15 bases at the 5' end of the clone and a 7 base insertion adjacent to position 1948 were also present. Evaluation of the entire mitochondrial genome in a subset of 11 tumors showed maximal amplification between mitochondrial positions 748 and 5882, and a lower degree of amplification elsewhere, with a recurrent deletion of a 1.2 kb EcoRI fragment noted in 5/11 (46%) tumors. The mitochondrial genome is frequently affected in human gliomas, and warrants further study to determine its role in glial malignancy.

Evidence for association of mitochondrial DNA sequence amplification and nuclear localization in human low-grade gliomas.

Gliomas are tumors which have been found to exhibit consistent genetic changes. Recent studies have shown mitochondrial DNA is also altered in these tumors, and include large deletions and gene amplification. Other studies of the mitochondrial genome in cancer have revealed a variety of different alterations, including the localization and insertion of mitochondrial DNA into the nucleus and nuclear genome in HeLa cells and diethylnitrosurea-induced hepatoma cells. Whether these changes are ontogenically early in the multistep pathway to the development of malignancy, or if this phenomenon occurs in human glial tumors is unknown. I sought to study these questions in a panel of unselected primary glial tumors of pathologically low grade. Fifteen tumors were assessed with a mitochondrial cDNA probe with homology to positions 1679-1948, and 2017-2057. All low-grade tumors revealed increases in copy number when compared to a normal brain control. Nuclear suspensions of these tumors were evaluated by fluorescent in situ hybridization (FISH), using the entire mitochondrial genome as a probe after labeling with rhodamine. All tumors showed evidence of mitochondrial sequence localization within the nuclei. A corresponding glioblastoma and two normal brain specimens were also evaluated which did not have amplification of the mitochondrial genome; FISH with the mitochondrial probe revealed minimal hybridization signal within the nuclei of these samples. Mitochondrial DNA nuclear localization can be found in primary low-grade brain neoplasms, and is correlated to increases in mitochondrial DNA.