Malignant Progression Of Astrocytomas Research Articles

Sohlh1 suppresses glioblastoma cell proliferation, migration, and invasion by inhibition of Wnt/β-catenin signaling.

Glioblastoma (GBM) is the most aggressive and highly invasive type of astrocytic tumors. Despite advances in diagnosis and therapy, the prognosis and survival time remain poor. Identifying key mediators of tumor cell proliferation, migration, and invasion is crucial to the development of new and more effective therapies. In this paper, we report the novel role of Spermatogenesis- and oogenesis- specific basic helix-loop-helix transcription factor1 (Sohlh1) in the inhibition of Wnt/β-catenin signaling and aggressive behaviors in GBM cells. Immunohistochemistry was performed to examine the expression of Sohlh1 and related proteins in astrocytomas. Human glioblastoma U87 and U251 cellswere transfected with appropriate plasmids and/or siRNAs to evaluate their functions on cell proliferation, migration, and invasion. Western blot and TOPflash luciferase assay were used to determine the involvement of Wnt/β-catenin signaling pathway in Sohlh1-mediated cellular activities in glioblastomas. We observed that Sohlh1 was downregulated in astrocytomas. The reduction in Sohlh1 expression was inversely correlated with the degree of malignancy in astrocytomas. In GBM cell lines, cellular proliferation, migration, and invasion were significantly enhanced after Sohlh1 knockdown, but significantly inhibited after Sohlh1 overexpression. These functional effects of Sohlh1 were achieved by upregulating GSK3β and inhibiting Wnt/β-catenin signaling. Our findings provide novel mechanistic insights of Sohlh1 in malignant progression of astrocytomas, suggesting that the level of Sohlh1 expression may be a predictor of astrocytoma behavior and further, Sohlh1 may serve as a potential therapeutic target for GBM.

Stathmin involvement in the maternal embryonic leucine zipper kinase pathway in glioblastoma

BackgroundMaternal Embryonic Leucine Zipper Kinase (MELK) is a serine/threonine kinase involved in cell cycle, differentiation, proliferation, and apoptosis. These multiple features are consistent with it being a potential anticancer target. Nevertheless, the MELK pathway in tumorigenesis is not yet completely understood. This study aims to identify proteins associated with MELK pathway in astrocytomas. To this end, proteomic data of the human glioma cell line U87MG transfected with siRNA for MELK were compared with non-target transfected control cells and compared with oligonucleotide microarray data.ResultsIn both assays, we identified stathmin/oncoprotein 18 (STMN1), involved in cell cycle. STMN1 gene expression was further assessed in a series of 154 astrocytomas and 22 non-neoplastic brain samples by qRT-PCR. STMN1 expression was significantly increased in malignant diffusely infiltrative astrocytomas compared with pilocytic astrocytoma (p < 0.0001). A strong correlation between MELK and STMN1 expressions was observed (r = 0.741, p < 0.0001) in glioblastoma (GBM) samples. However, no difference on survival times was found when compared GBM cases with upregulated and downregulated STMN1 (Breslow = 0.092, median survival time: 11 and 13 months, respectively). Functional assays knocking down MELK by siRNA in GBM cell line showed that gene and protein expression of both MELK and stathmin were diminished. On the other hand, when the same analysis was performed for STMN1, only stathmin gene and protein was silenced.ConclusionsThe results presented herein point stahtmin as a downstream target in the MELK pathway that plays a role in malignant progression of astrocytomas.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-016-0094-9) contains supplementary material, which is available to authorized users.

Inhibition of KIF14 Suppresses Tumor Cell Growth and Promotes Apoptosis in Human Glioblastoma

Background/Aims: The mitotic kinesin superfamily protein KIF14 is essential for cytokinesis and chromosome segregation, and increased KIF14 expression is related to a variety of human cancers. However, the role of KIF14 in the development and malignant progression of astrocytomas and the underlying mechanisms remain unclear. The present study examined the relation between KIF14 and the pathogenesis of malignant astrocytoma. Methods and Results: The role of KIF14 in astrocytoma development and progression was investigated by analyzing KIF14 expression using SYBR Green quantitative real-time RT-PCR, western blotting and immunohistochemistry in human astrocytoma and normal brain tissues. KIF14 expression was higher in astrocytoma samples, and was positively correlated with pathological grade and proliferative activity indicated by Ki-67 staining. SiRNA knockdown of KIF14 inhibited tumor growth in vitro and in vivo, attenuated anchorage-independent growth, and induced G2/M phase arrest, cytokinesis failure and apoptosis in glioblastoma cell lines in association with decreased AKT phosphorylation and activity. Conclusions: The upregulation of KIF14 in astrocytoma is associated with disease severity, and suppression of KIF14 inhibits cell proliferation and induces apoptosis through a mechanism involving the inactivation of AKT signaling, suggesting that KIF14 plays an important role in astrocytoma tumorigenesis and could be a promising molecular target for anticancer therapy.

Expression of delta-catenin is associated with progression of human astrocytoma

Backgroundδ-Catenin (CTNND2), which encodes a scaffold protein in humans, has been found in a few malignancies. However, the expression pattern and contribution of δ-catenin to astrocytoma progression are unclear.MethodsWe investigated δ-catenin expression in human astrocytoma samples and its function in astrocytoma cell lines using immunohistochemistry, siRNA knockdown, transfection, MTT, transwell migration and Rac1 pulldown techniques.Resultsδ-Catenin protein expression was detected in cytoplasm of astrocytoma cells by immunohistochemistry. Analysis showed that grade I astrocytoma (0%, 0/11) and glial cells from normal brain tissue exhibited negative staining. δ-Catenin expression was significantly higher in grade III-IV (35%, 29/84) compared to grade II astrocytoma cells (18%, 11/61); p < 0.01). In addition, CTNND2 overexpression promoted proliferation, invasion and Rac1 activity of U251 astrocytoma cells. Treatment of δ-catenin-transfected cells with a Rac1 inhibitor decreased Rac1 activity and invasion. δ-Catenin knockdown in U87 glioblastoma cell decreased cell proliferation, invasion and Rac1 activity.ConclusionThe results suggest that δ-catenin expression is associated with the malignant progression of astrocytoma and promotes astrocytoma cell invasion through upregulation of Rac1 activity. δ-Catenin expression levels may serve as a useful marker of the biological behavior of astrocytoma cells.

Grade-Specific Expression of Insulin-like Growth Factor–Binding Proteins-2, -3, and -5 in Astrocytomas: IGFBP-3 Emerges as a Strong Predictor of Survival in Patients with Newly Diagnosed Glioblastoma

Insulin-like growth factor (IGF)-binding protein (IGFBP) isoforms have been implicated in the pathogenesis of human neoplasms including glioma. In view of this, we evaluated the expression of IGFBP isoforms (IGFBP-2, -3, and -5) during malignant progression of astrocytoma and their prognostic significance in glioblastoma. The expression of IGFBP isoforms was analyzed in diffusely infiltrating astrocytomas by real-time quantitative PCR (n = 203) and immunohistochemistry (n = 256). Statistical methods were used to assess their grade-specific expression pattern and mRNA-protein intercorrelation. Survival analyses were done on a uniformly treated, prospective cohort of adult patients with newly diagnosed glioblastoma (n = 136) by using Cox regression models. The mean transcript levels of IGFBP-2 and -3 were significantly higher in glioblastomas (GBM) relative to anaplastic astrocytoma (AA), diffuse astrocytoma (DA), and controls whereas IGFBP-5 mRNA was higher in GBM relative to AA and controls (P < 0.05). By immunohistochemistry, the mean labeling index of all isoforms was significantly higher in GBM compared with AA, DA, and control (P < 0.05). A strong positive correlation was observed between their respective mRNA and protein expressions (P < 0.01). Multivariate analysis revealed IGFBP-3 expression (hazard ratio, 1.021; P = 0.030) and patient age (hazard ratio, 1.027; P = 0.007) to be associated with shorter survival in glioblastoma. This study shows the associations of IGFBP-2, -3, and -5 expression with increasing grades of malignancy in astrocytomas. IGFBP-3 is identified as a novel prognostic glioblastoma biomarker. The strong correlation between their mRNA and protein expression patterns suggests their role in the pathogenesis of these tumors. IGFBP isoforms have emerged as biomarkers with diagnostic and prognostic utility in astrocytomas.

Loss of prostaglandin D2 synthase: a key molecular event in the transition of a low-grade astrocytoma to an anaplastic astrocytoma

Reduction in the mRNA and protein expression of lipocalin-like prostaglandin D(2) (PGD(2)) synthase (PGDS), the main arachidonic acid metabolite produced in neurons and glial cells of the central nervous system, is a significant biological event involved in the malignant progression of astrocytomas and is predictive of poor survival. In vitro, the addition of the main PGDS metabolite, PGD(2), to A172 glioblastoma cells devoid of PGDS resulted in antiproliferative activity and cell death. In vitro PGD(2) substitution also enhanced the efficacy of cyclo-oxygenase-2 inhibitors. This finding has exciting implications for early interventional efforts for the grade 2 and 3 astrocytomas.

Utility of EGFR and PTEN numerical aberrations in the evaluation of diffusely infiltrating astrocytomas

Diffusely infiltrating astrocytomas are the most common primary brain tumors. As a group, they demonstrate an inherent tendency toward malignant progression. Histological grading using the guidelines of the World Health Organization (WHO) remains the gold standard for predicting the biological behavior of these tumors. Although useful, this grading system is often limited due to small sample sizes and the subjectivity in interpretation. Given the important roles for EGFR and PTEN in the malignant progression of astrocytomas, the authors hypothesized that the fraction of tumor cells with aberrations in these genetic loci would correlate with the histological grade. The authors evaluated 217 consecutive diffusely infiltrating astrocytomas that were graded using the WHO guidelines, including 16 diffuse astrocytomas (WHO Grade II), 72 anaplastic astrocytomas ([AAs] WHO Grade III), and 129 glioblastomas multiforme ([GBMs] WHO Grade IV). Cases were evaluated quantitatively using dual-color fluorescence in situ hybridization with probes for the EGFR and PTEN loci and the centromeres of chromosomes 7 and 10. The population of tumor cells with polysomy of chromosome 7 and the EGFR locus and monosomy of chromosome 10 and the PTEN locus correlated significantly with histological grade. In particular, high-grade astrocytomas (that is, AAs and GBMs) had elevated fractions of tumor cells with polysomy of chromosome 7 and the EGFR locus and monosomy of chromosome 10 and the PTEN locus. Using these findings, the authors generated a mathematical model capable of subcategorizing high-grade astrocytomas. The successful model incorporated only the percentage of tumor cells with polysomy of EGFR and monosomy of PTEN, as well as patient age. The predictions of this model correlated with survival in a manner similar to histopathological grading. The findings presented in this study emphasize the utility of combining histological interpretation and molecular testing in the evaluation of infiltrating astrocytomas. These results underscore the utility of building a grading framework that combines histopathological and molecular analysis.

Expression of cell cycle inhibitors p21, p27, p14 and p16 in gliomas. Correlation with classic prognostic factors and patients' outcome

Gliomas are among the most aggressive and treatment-refractory of all human tumors. The aim of the present study is to evaluate the role of the expression of cell cycle molecules as prognostic indicators in gliomas. We immunohistochemically analyzed the expression of p21, p27, p14, p16, p53 and proliferation marker Ki67, in 67 low and high grade astrocytic tumors. High grade tumors exhibited higher labeling indices for Ki67 (P = 0.004), p53 (P = 0.039) and slightly higher index for p21 (P = 0.07) compared to low grade tumors. p14 and p16 were more frequently present in low grade tumors (P = 0.001 and P = 0.052, respectively). Worse survival was correlated with high grade tumors (P < 0.0001) and higher Ki67 index (P < 0.0001). Cox regression analysis revealed that only age, grade and marginally Ki67 index were independent prognostic factors. Cell cycle alterations are involved in the malignant progression of astrocytomas, but only age, tumor grade and proliferating index can predict the outcome of the patients with glioma.

Candidate genes for the progression of malignant gliomas identified by microarray analysis

Malignant astrocytomas of World Health Organization (WHO) grade III or IV have a reduced median survival time, and possible pathways have been described for the progression of anaplastic astrocytomas and glioblastomas, but the molecular basis of malignant astrocytoma progression is still poorly understood. Microarray analysis provides the chance to accelerate studies by comparison of the expression of thousands of genes in these tumours and consequently identify targeting genes. We compared the transcriptional profile of 4,608 genes in tumours of 15 patients including 6 anaplastic astrocytomas (WHO grade III) and 9 glioblastomas (WHO grade IV) using microarray analysis. The microarray data were corroborated by real-time reverse transcription-polymerase chain reaction analysis of two selected genes. We identified 166 gene alterations with a fold change of 2 and higher whose mRNA levels differed (absolute value of the t statistic of 1.96) between the two malignant glioma groups. Further analyses confirmed same transcription directions for Olig2 and IL-13Ralpha2 in anaplastic astrocytomas as compared to glioblastomas. Microarray analyses with a close binary question reveal numerous interesting candidate genes, which need further histochemical testing after selection for confirmation. IL-13Ralpha2 and Olig2 have been identified and confirmed to be interesting candidate genes whose differential expression likely plays a role in malignant progression of astrocytomas.

IL-6 is required for glioma development in a mouse model.

The pleiotropic cytokine interleukin-6 (IL-6) contributes to malignant progression and apoptosis resistance of various cancer types. Although IL-6 is elevated in malignant gliomas, and glioma cells respond to IL-6, its functional role in gliomagenesis is unclear. We have investigated this role of IL-6 in a mouse model of spontaneous astrocytoma by crossbreeding glial fibrillary acidic protein (GFAP)-viral src oncogene transgenic mice with IL-6-deficient mice. We show here that ablation of IL-6 prevents tumour formation in these predisposed animals, but did not affect preneoplastic astrogliosis. Moreover, we demonstrate phosphorylation and nuclear translocation of the transcription factor signal transducer and activator of transcription (STAT)3, a prerequisite for IL-6 signalling, in 51 human gliomas WHO grade II-IV and all experimental mouse tumours investigated. Together with the observation that STAT3 activation increases with malignancy, these findings indicate an important role for IL-6 in the development and malignant progression of astrocytomas.

10q25.3 (DMBT1) copy number changes in astrocytoma grades II and IV.

In the literature, it has been suggested that loss of the 10q25-26 region, including the DMBT1 gene (10q25.3), is correlated with initiation and/or malignant progression of astrocytomas, although the results of the studies on the loss of heterozygosity that led to this assumption are not unequivocal. For this reason, using double-target fluorescence in situ hybridization, we compared copy number changes of 10q25.3 to those of the pericentromeric region (10q12) in 10 cases each of astrocytoma grades II and IV. The same specimens were analyzed for copy number changes of chromosome 1, as a marker for polyploidy, and chromosome 7, which is often gained in astrocytomas of all grades. Our results show that selective loss of the 10q25.3 region was present in 2 of 10 specimens in both astrocytoma grade II and grade IV, occurring only in tumors with polysomy for 10q12. Furthermore, astrocytoma grade II often showed polyploidy for chromosomes 1, 7, and 10 (8 of 10 specimens). In addition, astrocytoma grade IV frequently exhibited losses of chromosome 10 in a high percentage of nuclei. Although based on a small number of cases, the results clearly show that loss of the 10q25.3 region is uncommon in astrocytoma grade II and mostly coincident with loss of chromosome 10 in grade IV tumors. These data indicate that selective loss of the 10q25.3 region, including the DMBT1 gene, is not an initiating event in the genesis of astrocytoma grade II.

Brain Tumors, Update 2003: Imaging and the “New ‘New W.H.O.’”

The “new ‘new’ W.H.O.” schema of classifying and grading brain neoplasms is coming into worldwide use. Neuroradiologists should become familiar with new concepts such as primary and secondary glioblastoma, malignant progression of astrocytoma, the simplified classification of meningioma, and newly-identified neoplasms such as atypical teratoid/rhabdoid tumor and chordoid glioma.

AP-1 and heat shock protein 27 expression in human astrocytomas.

In previous work we have shown that the expression of heat shock protein 27 (Hsp27) is associated with anaplastic potential of astrocytomas (Anticancer Res 1997, 17:2677-2682). Heat shock protein-coding genes have been found to have a putative AP-1 (activator protein-1)-binding site in their promoter region and the synthesis of these proteins is induced by the same extracellular stimuli that also activate AP-1 (a homo/heterodimer of members of the Jun and Fos families). In order to detect the putative relation of Hsp27 with AP-1 activation in human astrocytomas we examined eighty astrocytic tumors with different grades of malignancy for c-Jun, c-Fos, and Hsp27 expression. Six pilocytic astrocytomas (WHO grade I), 15 diffuse fibrillary astrocytomas (WHO grade II), 19 anaplastic astrocytomas (WHO grade III), and 40 glioblastomas multiforme (WHO grade IV), were studied by immunohistochemistry using monoclonal and polyclonal antibodies directed against human Hsp27, c-Fos, and active (phosphorylated) forms of c-Jun (p-c-Jun). Monoclonal antibodies against the phosphorylated forms of the over-expressed MAP kinases JNK (c-Jun N-terminal kinase) (p-JNK) and p38 (p-p38) were also used. Overexpression of p-c-Jun, c-Fos and p-JNK was observed in the majority of glioblastomas (grade IV) whereas only minimal expression was noted in diffuse fibrillary astrocytomas (grade II). Hsp27 expression was observed only in the tumor specimens where c-Jun and c-Fos were co-expressed. AP-1/Hsp27 co-expression was associated with ascending grading of malignancy and it was independent of the proliferation index of the tumors. Our findings suggest that during malignant progression of astrocytomas there is activation of signal transduction cascade(s) culminating in AP-1 induction.

Identification of cadherin-11 down-regulation as a common response of astrocytoma cells to Transforming Growth Factor-α

Transforming growth factor-α (TGF-α) and its receptor are frequently co-expressed in high-grade astrocytomas, suggesting a role for TGF-α autocrine/paracrine loops in the malignant progression of astrocytomas. To identify genes that may be critical in mediating TGF-α impact on the malignant progression of astrocytomas, we have used cDNA arrays to investigate TGF-α effects on the gene expression profile of U-373 MG glioblastoma cells. We found that in these cells ∼ 50% of the TGF-α regulated genes code for cell motility/invasion-related proteins. TGF-α action on the expression of four of these proteins, α-catenin, IQGAP1, RhoA, and cadherin-11, was further investigated by immunoblotting in four astrocytoma cell lines and in normal astrocytes. The results demonstrate that the effects of TGF-α on IQGAP1, α-catenin, and RhoA expression are cell-line dependent. On the other hand, under TGF-α treatment, cadherin-11 expression is consistently decreased in all astrocytoma cell lines tested but is increased in normal astrocytes. In addition, we found that cadherin-11 is consistently down-regulated in astrocytomas versus normal brain tissues. Altogether, these results suggest that the down-regulation of cadherin-11 is a frequent molecular event in the neoplastic transformation of astrocytes and that this down-regulation may be initiated and/or amplified by TGF-α autocrine/paracrine loops during tumor progression.

Study of deletion of P16 gene in the progression of brain astrocytomas

Objective: To study the relationship between deletion of P16 gene and occurrence and progression of astrocytomas. Methods: The techniques of polymerase chain reaction (PCR) and immunohistochemistry were used to detect the deletion of exon2 of P16 gene and expression of P16 gene in 52 cases of Brain astrocytoma. Results: The deletion rate of exon2 of P16 gene in the tumors analyzed was 34.6%. Most of them with deletion of exon2 of p16 gene were high grade astrocytomas (grade III 42%, grade IV 50%). 61.5% of the tumors were absent from expression of p16 and the deletion rate of p16 protein increased with the grade of astrocytoma (X2=10.83,P<0.005). Conclusion: Deletion of p16 gene and protein may correlate with the malignant progression of astrocytoma.

Genetic factors in the pathogenesis of brain tumors

The biological properties of tumor cells are determined by, mostly acquired, alterations of proliferation-relevant genes that can provide valuable diagnostic and prognostic parameters. Meningiomas and gliomas are among the genetically best characterized solid tumors. Here, specific patterns of primary and secondary genetic aberrations have been identified and shown to be correlated with clinical parameters such as recurrency of meningiomas or malignant progression of astrocytomas. Focal progression leading to intratumoral heterogeneity, which is most strikingly seen in gliomas, results from complex mechanisms of mutation and selection of tumor cells that are also iatrogenically influenced through radiotherapy and chemotherapy.

Differential inducibilities of GFAP expression, cytostasis and apoptosis in primary cultures of human astrocytic tumours.

Glial fibrillary acidic protein (GFAP) is an astrocytic lineage-specific intermediate filament protein, and its expression or non-expression is inversely correlated with the tumourigenecity of astrocytoma cells. To estimate the GFAP levels of astrocytes in intracranial tumour tissues, we established primary cultures from six astrocytic tumour specimens and used a double-staining flow cytometric method to detect the different levels of GFAP among these primary cultures. Although these primary cultures exhibited the same Matrigel invasiveness, their GFAP expression is inversely related to the rate of cell growth and the histologic grade of the original tumour. Phenylacetate, 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate, which are potent inducers of differentiation in various cancer cells, have been examined for their effects on these primary cultures. Cytostasis was more or less caused by these compounds in all six primary cultures, but induction of GFAP was observed only in the primary culture derived from a less malignant astrocytoma specimen having the highest intrinsic GFAP level. Interestingly, this primary culture, but not others, also exhibited increased HRG-alpha expression after phenylacetate or sodium butyrate treatment. Loss of the inducibility of differentiation-related gene expression could be one of the events involved in the malignant progression of astrocytomas. In addition, the chemotherapeutic agent BiCNU has a killing effect on all six primary culture cells, with LD50 less than 60 nM. The underlying mechanism was through the induction of apoptosis in these primary culture cells regardless of their varying malignancies of original tumours. However, unlike colon cancer and leukaemia cells, sodium butyrate could not induce apoptosis within 4 days in these astrocytic tumour cells, indicating that the cell context of different cell types indeed determined the ability of sodium butyrate to induce apoptosis.

Increased expression of midkine during the progression of human astrocytomas

Midkine (MK), a member of a new family of neurotrophic and angiogenic growth factors whose expression is developmentally regulated, is produced in fetal astrocytes. Malignant astrocytomas, one of the most neovascularized tumors, are derived from astrocytes. There has been no investigation of the expression of MK in human astrocytic tumors. To determine if increased levels of MK expression correlate with the progression of human astrocytomas, we examined surgical specimens of astrocytic tumors of various grades using Northern and Western blotting. MK mRNA and protein expression levels were higher in high-grade astrocytomas (anaplastic astrocytomas and glioblastomas) than in low-grade astrocytomas. As shown by in situ hybridization, MK mRNA expression was intense in a majority of glioblastoma cells but was weak in a small number of low-grade astrocytoma cells. These findings suggest that MK expression correlates with the malignant progression of astrocytomas. The aberrant MK expression in high-grade astrocytomas may underlie their rapid growth and well-vascularized features.

Development and malignant progression of astrocytomas in GFAP-v-src transgenic mice.

We have generated a transgenic mouse model for astrocytoma by expressing the v-src kinase under control of the glial fibrillary acidic protein (GFAP) gene regulatory elements in astrocytes. Abnormal astrogliosis was observed in all transgenic animals already at 2 weeks postnatally, frequently followed by the development of dysplastic changes. Later, small proliferative foci arose, and overt astrocytoma developed in the brain and spinal cord in 14.4% of mice after a follow up time of 65 weeks. While early lesions were histologically consistent with low-grade astrocytoma, at later stages most tumors were highly mitotic and frankly malignant. Vascular endothelial growth factor (VEGF) was expressed by tumor cells already at early stages, suggesting induction by v-src, and it was most pronounced in pseudopalisading cells surrounding necrotic areas, implying additional upregulation by hypoxia. In larger lesions, mitotic activity and expression of flk-1, the cognate receptor of VEGF were induced in endothelial cells. Therefore, end-stage tumors mimicked the morphological and molecular characteristics of human glioblastoma multiforme. Time course and stochastic nature of the process indicate that v-src did not suffice for malignant transformation, and that astrocytomas were the result of a multistep process necessitating co-operation of additional genetic events.

Loss of heterozygosity of microsatellite loci on chromosome 9p in astrocytic tumors and its prognostic implications.

We analyzed 19 samples of various astrocytic tumors (3 astrocytomas, 5 anaplastic astrocytomas, and 11 glioblastomas) for loss of heterozygosity (LOH) on chromosome 9p at 6 microsatellite loci (D9S54, IFNA, D9S171, D9S104, D9S165, and D9S166). Polymerase chain reaction was performed and the products were electrophoresed on polyacrylamide gel. As many as 16 of the 19 samples (84%) exhibited LOH. Three of the 7 informative loci (43%) showed LOH at D9S54, 7 of 17 (41%) at IFNA, 8 of 14 (57%) at D9S171, 7 of 14 (50%) at D9S104, 4 of 8 (50%) at D9S165, and 2 of 7 (29%) at D9S166. LOH was recognized in 57% of the informative loci in anaplastic astrocytomas and 54% in glioblastomas, while it was seen in only 8% of the astrocytomas. Accumulation of LOH with progression or recurrence of tumor was seen in 2 patients. Although, the survival period of the patients correlated well to the histological types of astrocytic tumors, we could not find any obvious correlations between the presence/absence of LOH and the survival period in these patients. In conclusion, we speculate that LOH on chromosome 9p is involved in malignant progression of astrocytomas, but has no significance in predicting survival period in these patients.