Determinants of exposure to endocrine disruptors following hurricane Harvey.

Hurricane Harvey was a category four storm that induced catastrophic flooding in the Houston metropolitan area. Following the hurricane there was increased concern regarding chemical exposures due to damage caused by flood waters and emergency excess emissions from industrial facilities. This study utilized personal passive samplers in the form of silicone wristbands in Houston, TX to both assess chemical exposure to endocrine disrupting chemicals (EDCs) immediately after the hurricane and determine participant characteristics associated with higher concentrations of exposure. Participants from the Houston-3H cohort (n = 172) wore a wristband for seven days and completed a questionnaire to determine various flood-related and demographic variables. Bivariate and multivariate analysis indicated that living in an area with a high Area Deprivation Index (ADI) (indicative of low socioeconomic status), identifying as Black/African American or Latino, and living in the Houston neighborhoods of Baytown and East Houston were associated with increased exposure to EDCs. These results provide evidence of racial/ethnic and socioeconomic injustices in exposure to EDCs in the Houston Metropolitan Area. Since the multiple regression models conducted did not fully explain exposure (0.047 < R2 < 0.34), more research is needed on the direct sources of EDCs within this area to create effective exposure mitigation strategies.

Single π 0 production off neutrons bound in deuteron with linearly polarized photons.

The quasifree γ → d → π 0 n ( p ) photon beam asymmetry, Σ , has been measured at photon energies, E γ , from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49 ∘ to 148 ∘ . In this kinematic region, polarization observables are sensitive to contributions from the Δ ( 1232 ) and N(1440) resonances. The extracted values of Σ have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn-Gatchina analyses; while a revised SAID fit, including the new Σ measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict π 0 n photoproduction observables, based on fits to published data in the channels π 0 p , π + n and π - p .

Testing for causality between systematically identified risk factors and glioma: a Mendelian randomization study.

BACKGROUND: Whilst epidemiological studies have provided evidence of associations between certain risk factors and glioma onset, inferring causality has proven challenging. Using Mendelian randomization (MR), we assessed whether associations of 36 reported glioma risk factors showed evidence of a causal relationship. METHODS: We performed a systematic search of MEDLINE from inception to October 2018 to identify candidate risk factors and conducted a meta-analysis of two glioma genome-wide association studies (5739 cases and 5501 controls) to form our exposure and outcome datasets. MR analyses were performed using genetic variants to proxy for candidate risk factors. We investigated whether risk factors differed by subtype diagnosis (either glioblastoma (n = 3112) or non-glioblastoma (n = 2411)). MR estimates for each risk factor were determined using multiplicative random effects inverse-variance weighting (IVW). Sensitivity analyses investigated potential pleiotropy using MR-Egger regression, the weighted median estimator, and the mode-based estimator. To increase power, trait-specific polygenic risk scores were used to test the association of a genetically predicated increase in each risk factor with glioma onset. RESULTS: Our systematic search identified 36 risk factors that could be proxied using genetic variants. Using MR, we found evidence that four genetically predicted traits increased risk of glioma, glioblastoma or non-glioblastoma: longer leukocyte telomere length, liability to allergic disease, increased alcohol consumption and liability to childhood extreme obesity (> 3 standard deviations from the mean). Two traits decreased risk of non-glioblastoma cancers: increased low-density lipoprotein cholesterol (LDLc) and triglyceride levels. Our findings were similar across sensitivity analyses that made allowance for pleiotropy (genetic confounding). CONCLUSIONS: Our comprehensive investigation provides evidence of a causal link between both genetically predicted leukocyte telomere length, allergic disease, alcohol consumption, childhood extreme obesity, and LDLc and triglyceride levels, and glioma. The findings from our study warrant further research to uncover mechanisms that implicate these traits in glioma onset.

Study of η and η' Photoproduction at MAMI.

The reactions γp→ηp and γp→η^{'}p are measured from their thresholds up to the center-of-mass energy W=1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the energies in the vicinity of the η^{'} threshold, W=1896 MeV (E_{γ}=1447 MeV). Within the framework of a revised ηMAID isobar model, the cusp, in connection with a steep rise of the η^{'} total cross section from its threshold, can only be explained by a strong coupling of the poorly known N(1895)1/2^{-} state to both ηp and η^{'}p. Including the new high-accuracy results in the ηMAID fit to available η and η^{'} photoproduction data allows the determination of the N(1895)1/2^{-} properties.

Insight into the Narrow Structure in η Photoproduction on the Neutron from Helicity-Dependent Cross Sections.

The double polarization observable E and the helicity dependent cross sections σ_{1/2} and σ_{3/2} were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π^{0}. The results show that the narrow structure previously observed in η photoproduction from the neutron is only apparent in σ_{1/2} and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that contribute to this partial wave in η production are only N 1/2^{-} (S_{11}) and N 1/2^{+} (P_{11}). Furthermore, the extracted Legendre coefficients of the angular distributions for σ_{1/2} are in good agreement with recent reaction model predictions assuming a narrow resonance in the P_{11} wave as the origin of this structure.

Low penetrance susceptibility to glioma is caused by the TP53 variant rs78378222.

BACKGROUND: Most of the heritable risk of glioma is presently unaccounted for by mutations in known genes. In addition to rare inactivating germline mutations in TP53 causing glioma in the context of the Li-Fraumeni syndrome, polymorphic variation in TP53 may also contribute to the risk of developing glioma. METHODS: To comprehensively evaluate the impact of variation in TP53 on risk, we analysed 23 tagSNPs and imputed 2377 unobserved genotypes in four series totaling 4147 glioma cases and 7435 controls. RESULTS: The strongest validated association signal was shown by the imputed single-nucleotide polymorphism (SNP) rs78378222 (P=6.86 × 10(-24), minor allele frequency ~0.013). Confirmatory genotyping confirmed the high quality of the imputation. The association between rs78378222 and risk was seen for both glioblastoma multiforme (GBM) and non-GBM tumours. We comprehensively examined the relationship between rs78378222 and overall survival in two of the case series totaling 1699 individuals. Despite employing statistical tests sensitive to the detection of differences in early survival, no association was shown. CONCLUSION: Our data provided strong validation of rs78378222 as a risk factor for glioma but do not support the tenet that the polymorphism being a clinically useful prognostic marker. Acquired TP53 inactivation is a common feature of glioma. As rs78378222 changes the polyadenylation signal of TP53 leading to impaired 3'-end processing of TP53 mRNA, the SNP has strong plausibility for being directly functional contributing to the aetiological basis of glioma.

Prognostic value of the trichorhinophalangeal syndrome-1 (TRPS-1), a GATA family transcription factor, in early-stage breast cancer.

BACKGROUND: TRPS-1 is a new GATA transcription factor that is differentially expressed in breast cancer (BC) where it been found recently to regulate epithelial-to-mesenchymal transition (EMT). PATIENTS AND METHODS: We carried out a quantitative immunohistochemistry (qIHC) analysis of TRPS-1 expression in 341 primary-stage I-III BC samples in relation to patient clinical characteristics as well as its prognostic value, especially in an estrogen receptor-positive (ER+) subgroup. RESULTS: Higher TRPS-1 expression was significantly associated with a number of clinical and pathological characteristics as well as with improved overall survival (OS) and disease-free survival (DFS). Among stage I/II ER+ BC patients who received endocrine therapy alone, those with high TRPS-1 expression had significantly longer OS and DFS. There was also a strong association between TRPS-1 levels and the EMT marker E-cadherin in the ER+ invasive ductal carcinoma cases. Analysis of gene expression data on a panel of BC lines found that TRPS-1 expression was low or absent in BC lines having enriched mesenchymal features. CONCLUSIONS: Our data indicated that TRPS-1 is an independent prognostic marker in early-stage BC and a new EMT marker that can distinguish patients with ER+ BC who will respond longer to adjuvant endocrine therapy.

Genetic variations in VEGF and VEGFR2 and glioblastoma outcome.

Vascular endothelial growth factor (VEGF) and its receptors (VEGFR) are central components in the development and progression of glioblastoma. To investigate if genetic variation in VEGF and VEGFR2 is associated with glioblastoma prognosis, we examined blood samples from 154 glioblastoma cases collected in Sweden and Denmark between 2000 and 2004. Seventeen tagging single nucleotide polymorphisms (SNPs) in VEGF and 27 in VEGFR2 were genotyped and analysed, covering 90% of the genetic variability within the genes. In VEGF, we found no SNPs associated with survival. In VEGFR2, we found two SNPs significantly associated to survival, namely rs2071559 and rs12502008. However, these results are likely to be false positives due to multiple testing and could not be confirmed in a separate dataset. Overall, this study provides little evidence that VEGF and VEGFR2 polymorphisms are important for glioblastoma survival.

Validation of a breast cancer risk assessment model in women with a positive family history.

BACKGROUND: Gail et al. developed a statistical model for estimating the risk of developing breast cancer in white women screened annually with mammography. This model is used for counseling and for admission to clinical trials. PURPOSE: We evaluated the model prospectively in a cohort of women with a family history of breast cancer. METHODS: We followed women who participated in the American Cancer Society 1987 Texas Breast Screening Project. The model was evaluated by comparing the observed (O) and expected (E) numbers of breast cancers using composite background rates from both the Breast Cancer Detection and Demonstration Project and the Surveillance, Epidemiology, and End Results program of the National Cancer Institute. Data were partitioned by adherence to American Cancer Society screening guidelines. RESULTS: The Gail et al. model predicted the risk well among women who adhered to the American Cancer Society guidelines (O/E = 1.12; 95% confidence interval = 0.75-1.61) but overpredicted risk for women who did not adhere to the guidelines. There was an indication that the model overpredicted risk for women younger than 60 years old and underpredicted risk in women aged 60 years and older. CONCLUSIONS: Overall, the Gail et al. model accurately predicts risk in women with a family history of breast cancer and who adhere to American Cancer Society screening guidelines. Thus, the model should be used as it was intended, for women who receive annual mammograms.

Mutagen sensitivity as a risk factor for second malignant tumors following malignancies of the upper aerodigestive tract.

BACKGROUND: Second malignant tumors in patients successfully treated for an initial cancer of the upper aerodigestive tract are an important cause of morbidity and mortality. Biologic markers capable of identifying high-risk subgroups of patients who could be targeted for intensive clinical surveillance, therefore, have immense therapeutic and prognostic relevance. We previously demonstrated in a pilot study of 84 patients with cancers of the upper aerodigestive tract that mutagen sensitivity was a significant predictor of risk of developing second malignant tumors. PURPOSE: We extended the study to include 278 patients diagnosed with previously untreated cancers of the upper aerodigestive tract from 1987 to August 1993. METHODS: For each patient, base-line (pretreatment) mutagen sensitivity was measured in vitro in 50 metaphases established from peripheral lymphocyte cultures. Patients with an average of more than 1 chromosomal break/cell were deemed mutagen hypersensitive. Cox proportional hazards analysis was used to predict the risk of developing second malignant tumors associated with mutagen sensitivity. RESULTS: Overall, 44% of the case group exhibited mutagen hypersensitivity. There were no differences in the distribution of mutagen hypersensitivity by site, sex, stage of disease, or smoking status. There were 17 synchronous and 11 metachronous cancers, of which 15 (54%) were smoking-related malignancies. Sixteen (13.1%) of the mutagen-sensitive patients developed second malignant tumors, compared with 12 (7.7%) of the nonsensitive patients. The mean break/cell value (+/- SD) for patients developing second malignant tumors was 1.17 (+/- 0.54), compared with 0.98 (+/- 0.44) for patients with only one cancer (P = .04). Mutagen hypersensitivity conferred a relative risk of 2.67 (95% confidence interval = 1.22-5.79) of developing second malignant tumors. CONCLUSIONS: Mutagen hypersensitivity increases the risk of developing second malignant tumors. IMPLICATIONS: Future research should focus on the molecular mechanisms underlying mutagen sensitivity.

Germline p53 gene mutations in subsets of glioma patients.

BACKGROUND: Heritable germline mutations of the p53 gene have been described in patients with Li-Fraumeni syndrome, occasionally in nonfamilial malignancies such as multifocal osteosarcoma, in a small subgroup of young patients with two or more primary malignancies, and in patients with sporadic breast carcinoma. We recently reported that multifocal gliomas are frequently associated with other primary malignancies, and we hypothesized that genetic alterations may account for this phenomenon. PURPOSE: We examined the frequency of germline p53 gene mutations in patients with glioma and either multifocality of lesions, history of an additional primary (different) malignancy, or a family history of cancer. METHODS: Lymphocytes from 51 glioma patients were analyzed for germline p53 gene mutations using RNA-polymerase chain reaction analysis, single-strand conformation polymorphism, and gene sequencing techniques. RESULTS: Germline p53 gene mutations were detected in six of 19 patients with multifocal glioma, including two with family history of cancer, one with another primary malignancy, and two with all three risk factors; one of four patients with unifocal glioma, another primary malignancy, and a family history of cancer; and two of 15 patients with unifocal glioma and a family history of cancer but no second malignancies. No mutations were detected in the patient with unifocal glioma and another malignancy or in the 12 control patients with unifocal glioma and no second malignancies or family history of cancer. Patients having mutations were younger than other patients in the same group. CONCLUSIONS: Germline p53 mutations are frequent in patients with multifocal glioma, glioma and another primary malignancy, and glioma associated with a family history of cancer, particularly if these factors are combined. IMPLICATIONS: Relatives at high risk can be identified for genetic counseling, early cancer detection, and possible enrollment in chemoprevention trials.

Gamma-radiation sensitivity and risk of glioma.

BACKGROUND: About 9% of human cancers are brain tumors, of which 90% are gliomas. gamma-Radiation has been identified as a risk factor for brain tumors. In a previous pilot study, we found that lymphocytes from patients with glioma were more sensitive to gamma-radiation than were lymphocytes from matched control subjects. In this larger case-control study, we compared the gamma-radiation sensitivity of lymphocytes from glioma patients with those from control subjects and investigated the association between mutagen sensitivity and the risk for developing glioma. METHODS: We used a mutagen sensitivity assay (an indirect measure of DNA repair activity) to assess chromosomal damage. We gamma-irradiated (1.5 Gy) short-term lymphocyte cultures from 219 case patients with glioma and from 238 healthy control subjects frequency matched by age and sex. After irradiation, cells were cultured for 4 hours, and then Colcemid was added for 1 hour to arrest cells in mitosis. Fifty metaphases were randomly selected for each sample and scored for chromatid breaks. All statistical tests were two-sided. RESULTS: We observed a statistically significantly higher frequency of chromatid breaks per cell from case patients with glioma (mean = 0.55; 95% confidence interval [CI] = 0.50 to 0.59) than from control subjects (mean = 0.44; 95% CI = 0.41 to 0.48) (P<.001). Using 0.40 (the median number of chromatid breaks per cell in control subjects) as the cut point for defining mutagen sensitivity and adjusting for age, sex, and smoking status, we found that mutagen sensitivity was statistically significantly associated with an increased risk for glioma (odds ratio = 2.09; 95% CI = 1.43 to 3.06). When the data were divided into tertiles, the relative risk for glioma increased from the lowest tertile to the highest tertile (trend test, P<.001). CONCLUSION: gamma-Radiation-induced mutagen sensitivity of lymphocytes may be associated with an increased risk for glioma, a result that supports our earlier preliminary findings.

Comparative allelotype of in situ and invasive human breast cancer: high frequency of microsatellite instability in lobular breast carcinomas.

To better understand the timing for presentation of allelic losses in human breast carcinogenesis, we compared the allelotypic profile of 23 in situ ductal carcinomas with that of 29 invasive ductal carcinomas. We also compared the allelotype of the invasive ductal breast carcinomas with that of 23 invasive lobular breast carcinomas. These studies were performed by means of microsatellite length polymorphisms from microdissected paraffin sections. We observed that involvement of chromosome arms 1p, 3p, 3q, 6p, 16p, 18p, 18q, 22q, and possibly 6q and 11p appear to be late events in breast cancer progression because allelic losses or imbalances affecting these areas were observed with very low frequency at the in situ stage. On the other hand, allelic imbalances and losses affecting chromosome arms 7p, 16q, 17p, and 17q appear to be early abnormalities because they were observed in approximately 25-30% of ductal carcinoma in situ lesions. Allelic losses and imbalances affecting the 8p arm were frequently observed in invasive lobular breast carcinomas. It was also interesting that microsatellite instability, also known as replication error (RER) phenotype, was found to occur at a high frequency in invasive lobular breast carcinomas because 9 of 23 (39%) were RER+, compared with 7 of 52 (13.5%) RER+ of breast cancers with ductal differentiation (P = 0.012, chi 2 test). Our findings provide for the first time molecular evidence suggesting that invasive lobular breast carcinomas may arise by a different mechanism of carcinogenesis than ductal carcinomas.

Benzo(a)pyrene diol epoxide-induced chromosomal aberrations and risk of lung cancer.

Benzo(a)pyrene is considered a classic DNA-damaging carcinogen and is one of a multitude of polycyclic aromatic hydrocarbons commonly found in tobacco smoke and in the ambient environment. In this report, we describe the characteristics of chromosomal aberrations induced in vitro by activated benzo(a)pyrene diol epoxide (BPDE) in lymphocyte cultures of 172 normal individuals ages 19-95 years and present the analysis of a pilot case-control study of 33 lung cancer patients and 96 selected controls without history of cancer and frequency matched on age (50-85 years) to the cases. The BPDE-induced chromosomal aberrations were predominantly single chromatid breaks, with few isochromatid breaks or exchange figures. In the 172 normal subjects, the frequencies of both spontaneous and BPDE-induced chromatid breaks were not correlated with age, sex, ethnicity, or tobacco use. However, the frequency of BPDE-induced chromatid breaks was significantly correlated with the frequency of spontaneous chromatid breaks (r = 0.19, P < 0.05). In addition, Hispanics had significantly higher mean BPDE-induced chromatid breaks than did non-Hispanic whites (P < 0.01). From the case-control analyses, the frequency of BPDE-induced chromosomal aberrations was significantly higher in cases (mean, 0.67 breaks/cell) than in controls (mean, 0.41 breaks/cell; P < 0.0001). An adjusted odds ratio of 6.53 (95% confidence interval, 3.74-11.4) for lung cancer was associated with increased frequency of these chromosomal aberrations. The higher rate of BPDE-induced chromosomal aberrations may be due to inefficient DNA repair. These findings warrant additional molecular epidemiological studies. The BPDE mutagen sensitivity assay will facilitate epidemiological studies of genetic susceptibility to smoking-related cancers.

Mutagen sensitivity and risk of gliomas: a case-control analysis.

Although the risk factors contributing to the etiology of brain tumors remain largely unknown, this pilot study suggests that genetically determined sensitivity to environmental carcinogens may play a role in the pathogenesis of these tumors. In this study, we examined short-term lymphocyte cultures from 45 adult malignant glioma patients and 117 age-, sex-, and ethnicity-matched healthy controls for mutagen-induced chromatid breaks and evaluated their family history of cancer, smoking, and demographic variables to ascertain the association between mutagen sensitivity and risk of brain tumors. The mutagen selected was gamma-radiation. The mean number of induced breaks/cell was 0.72 (SD=0.45) for the cases and 0.45 (SD = 0.35) for the controls (P < 0.0001). Using the median number of induced breaks/cell in the controls as the breakpoint for defining mutagen sensitivity, we observed an unadjusted odds ratio of 5.36 (95% confidence interval = 2.12-13.69) for mutagen sensitivity and brain tumor risk and an adjusted odds ratio of 5.79 (2.26-14.83), when we controlled for epidemiological risk factors including smoking, race, income, and education. Although a larger study is needed to confirm this intriguing result, these preliminary findings suggest that increased sensitivity to radiation is an independent risk factor for gliomas.

Reduced expression of mismatch repair genes measured by multiplex reverse transcription-polymerase chain reaction in human gliomas.

Microsatellite instability (MIN) is frequently observed in hereditary nonpolyposis colon cancer and in other sporadic cancers including gliomas. Abnormalities in at least one of five mismatch repair (MMR) genes are implicated in the development of cancers in hereditary nonpolyposis colon cancer and the associated MIN. Using a newly developed multiplex reverse transcription-PCR assay, we evaluated the expression of the five known human MMR genes (hMSH2, hMLH1, hPMS1, hPMS2, and GTBP) in human gliomas by measuring simultaneously the relative levels of the transcripts. The beta-actin gene was used as an internal control for RNA degradation and DNA contamination and as a reference for quantifying the levels of their transcripts. Of the 33 gliomas examined, 42% (14) had low expression of hMSH2 (at least 4-5-fold lower than normal mean), 21% (7) had low expression of hMLH1, and 18% (6) had low expression of hPMS1 compared with the expression in the lymphocytes from 13 normal individuals. Furthermore, six of the 33 (18%) tumor samples had decreased expression of more than one MMR gene. Two of these six patients with multiple gene abnormalities had second primary cancers, and an additional patient had multifocal gliomas. Further molecular analysis of available DNA samples indicated that one of five of those tumors with aberrant expression of MMR genes had MIN, as compared with none of five tumors with normal expression. These data suggest that reduced expression of MMR genes is frequent in human gliomas and that aberrant expression of more than one MMR gene may be associated with increased risk of second primary malignancies in glioma patients.

Sensitivity to benzo(a)pyrene diol-epoxide associated with risk of breast cancer in young women and modulation by glutathione S-transferase polymorphisms: a case-control study.

Mounting epidemiological evidence suggests that smoking may play a role in the etiology of breast cancer. Because smoking-related DNA adducts are detectable in both normal and malignant breast tissues, we hypothesized that breast cancer patients may be sensitive to tobacco-induced carcinogenesis, and this sensitivity could be modulated by variants of metabolic genes. To test this hypothesis, we evaluated benzo(a)pyrene diol-epoxide (BPDE)-induced mutagen sensitivity and polymorphisms of GSTM1 and GSTT1 in a pilot case-control study of breast cancer. Short-term cell cultures were established from blood samples of 100 female breast cancer patients and 105 healthy controls. After 5 h of in vitro exposure to 4 microM of BPDE, we harvested the lymphocytes for cytogenetic evaluation and recorded and compared the frequency of BPDE-induced chromatid breaks between cases and controls. We used a multiplex PCR-based assay to simultaneously detect polymorphisms of GSTM1 and GSTT1 from genomic DNA. We performed univariate and multivariate logistic regression analyses and calculated odds ratios (OR) and 95% confidence intervals (CIs). Cases had a significantly higher frequency of chromatid breaks than did controls (P < 0.0001). The level of chromatid breaks greater than the median value of controls was associated with a >3-fold increased risk of breast cancer [adjusted odds ratio (ORadj) = 3.11; 95% CI = 1.72-5.64]. The risk was more pronounced in those who were < 45 years (ORadj = 4.79; 95% CI = 1.87-12.3), ever-smokers (ORadj = 5.55; 95% CI = 1.85-16.6), alcohol drinkers (ORadj = 4.64; 95% CI = 1.70-12.7), and those who had the GSTT1 null variant (ORadj = 8.01; 95% CI = 1.16-55.3). These data suggest that sensitivity to BPDE-induced chromosomal aberrations may contribute to the risk of developing breast cancer, and such sensitivity may be modulated by both genetic and environmental factors. Larger studies are needed to confirm our findings.

Differential expression of MMAC/PTEN in glioblastoma multiforme: relationship to localization and prognosis.

MMAC/PTEN, a tumor suppressor gene located on chromosome 10q, has recently been shown to act as a phosphatidylinositol 3,4,5-triphosphate phosphatase and to modulate cell growth and apoptosis. Somatic mutations of MMAC/PTEN have been reported in a number of human cancers, especially in glioblastoma multiforme (GBM), although the number of identified mutations (approximately 10-35%) is significantly lower than the frequency of LOH affecting the MMAC/PTEN locus in the specimens (approximately 75-95%). To further investigate the possible alterations that may affect MMAC/PTEN, we examined the expression of the gene by reverse transcription-PCR in a series of gliomas. A significant difference (P < 0.001) was observed between the expression of MMAC/PTEN in GBMs versus lower grades of gliomas, thus mimicking the difference in allelic deletion associated with the locus in these tumors. Furthermore, Kaplan-Meier survival plots, adjusted for age and tumor grade, showed a significantly better prognosis for patients whose tumors expressed high levels of MMAC/PTEN. Additionally, immunostaining of GBMs revealed little or no MMAC/PTEN expression in about two-thirds of the tumors, whereas the other approximately one-third of tumors had significantly higher levels of expression. However, in about two-thirds of the high-expressing specimens, a heterogeneous pattern of expression was observed, indicating that certain cells within the tumor failed to express MMAC/PTEN. The combination of these results suggest that, in addition to molecular alterations affecting the gene, altered expression of MMAC/PTEN may play a significant role in the progression of GBM and patient outcome.

Mutations of the p16 gene in gliomas.

In the present study we investigated the frequency of p16 gene exon 2 mutations in 35 malignant gliomas, using either direct sequencing of the PCR products or cloning into the pCRII vector and sequencing of the cloned PCR products. No mutations were detected during direct sequencing of the PCR products. However, after sequencing of individual clones, we found multiple mutations in 5 tumors involving codons 73(GCC to ACC, Ala to Thr), 76 (GCC to GTC, Ala to Val), 85(GCT to ACT, Ala to Thr), 98(CAC to TAC, His to Tyr), 102 (GCG to GTG, Ala to Val), 106 (GTG to ATG, Val to Met), 107 (CGC to TGC, Arg to Cys), 127 (GCA to GTA, Ala to Val), 128 (CGG to TGG, Arg to Trp) and 136 (GGC to GAC, Gly to Asp). Mutations were found only in glioblastomas and were either C to T or G to A transitions. Each mutation was detected in a small percentage of tumor cells (1.3-22%) using individual colony sequencing and southern hybridization with mutant oligonucleotides, consistent with the heterogenous cell population of glioblastomas. The presence of p16 gene mutations only in glioblastomas suggests that they are late events in glioma development.

Prognostic significance of p53 immunoreactivity in patients with glioma.

Abnormal p53 as revealed by immunostaining has been shown to be a predictor of poor outcome in a variety of malignant tumors. This study examines the relationship of p53 immunostaining and survival in 182 adult patients with gliomas. Tumor tissues obtained from patients with glioma within 4 months of initial diagnosis were investigated by immunohistochemical analysis for detection of p53 protein abnormalities using the monoclonal antibody PAb 1801. There were 122 patients with glioblastoma multiforme, 48 patients with anaplastic glioma, and 12 patients with low-grade glioma. Among these patients, 73 of those with glioblastoma multiforme, 35 with anaplastic glioma, and 6 with low-grade glioma had positive p53 immunoreactivity. Kaplan-Meier survival plots (log rank test) showed that the patients with anaplastic astrocytoma or low-grade glioma and p53-positive tumors had longer survival times compared to the patients with p53-negative tumors. No differences in survival were detected among the glioblastoma patients. Cox proportional hazards regression analysis, adjusted for age at diagnosis, showed that the p53 positivity was a significant predictor of longer survival (relative risk = 0.56; 95% confidence intervals = 0.35, 0.90; P = 0. 015) in anaplastic astrocytoma patients, but not in glioblastoma patients (relative risk = 1.03; 95% confidence intervals = 0.82, 1. 29; P = 0.80). These results suggest that anaplastic glioma patients with p53 protein alterations may have a better response to chemoradiation, possibly because the malignant cells cannot arrest in G1 to correct lethal damage induced by chemotherapy or radiotherapy.