Allostatic score and its associations with demographics, healthy behaviors, tumor characteristics, and mitochondrial DNA among breast cancer patients.

INTRODUCTION: Allostatic load (AL), a composite index, has been used to capture variation in life-course stresses. However, few studies have been carried out among breast cancer patients. METHODS: In this study, we examined the cross-sectional association of AL with demographics, healthy behaviors, tumor characteristics, and mitochondrial DNA copy number in breast cancer patients. The study used a sub-sample of 934 women with newly diagnosed breast cancer at M.D. Anderson from 2013 to 2018. To construct the AL score, the study used a battery of seventeen factors that represents the activity of five physiological systems: metabolic, cardiovascular, immunological, renal, and liver. RESULTS: AL was positively associated with the age of disease diagnosis (P = 0.002), and was higher in Black and Hispanic populations than White (P = 0.001 and 0.032, respectively). AL was also found more abundant in those who experienced marital dissolution (P = 0.006), lacked a college education (P = 0.045), currently smoked (P = 0.011), and had low levels of physical activity (P = 0.037) than their counterparts. The study then found that higher AL was associated with increased odds of having poorly differentiated tumors (Odds ratio (OR): 1.40, 95% confidence interval (CI): 1.28, 1.62). An additional significant association was observed between AL with estrogen receptor negative (ER-) (OR = 1.56, 95%CI: 1.02, 2.36) among Black patients. Finally, we observed a significant positive correlation between AL with leukocyte mitochondrial DNA copy number variation (P < 0.001). CONCLUSIONS: We conclude AL is influenced by selected demographics and healthy behaviors, and further is correlated with tumor characteristics and mitochondrial DNA copy number in breast cancer patients.

Homologous recombination repair capacity in peripheral blood lymphocytes and breast cancer risk.

Deficiency in homologous recombination repair (HRR) capacity is frequently observed in breast tumors. However, whether HRR deficiency is a tumor-specific biomarker or a risk factor for breast cancer is unknown. In this two-stage study, using a host cell reactivation assay, we assessed the relationship between HRR capacity in peripheral blood lymphocytes (PBLs) and breast cancer risk. The discovery stage included 152 breast cancer patients and 152 healthy controls matched on age and race. HRR capacity was found to be significantly lower in Black women than in White women among controls (P = 0.015) and cases (P = 0.012). Among cases, triple negative breast cancer patients had significantly lower HRR capacity than ER+/PR+ breast cancer patients (P = 0.006). In risk assessment, HRR capacity was found to be significantly lower in cases than in controls (P < 0.001), and decreased HRR capacity was associated with 1.42-fold increased risk of breast cancer (95% CI: 1.21, 2.53). In the validation stage, we assessed HRR capacity in a nested case-control study using pre-diagnostic samples. We found that decreased HRR capacity was associated with 1.21-fold increased risk of breast cancer (95% CI: 1.04, 4.58). In summary, our results demonstrate that decreased HRR capacity in PBLs is a risk factor for breast cancer.

Identification of metabolites in plasma for predicting survival in glioblastoma.

Circulating metabolomics profiling holds prognostic potential. However, such efforts have not been extensively carried out in glioblastoma. In this study, two-step (training and testing) metabolomics profiling was conducted from the plasma samples of 159 glioblastoma patients. Metabolomics profiling was tested for correlation with 2-year overall and disease-free survivals. Arginine, methionine, and kynurenate levels were significantly associated with 2-year overall survival in both the training and testing sets. In the combined sets, elevated levels of arginine and methionine were associated with a 34% and 37% increased probability whereas kynurenate was associated with a 55% decreased probability of 2-year overall survival. These three metabolites were also significantly associated with 2-year disease-free survival. Risk scores were generated using the linear combination of levels of these significant metabolites. Glioblastoma patients with a high-risk score exhibited a 2.41-fold decreased probability of 2-year overall survival (hazard ratio (HR) = 2.41; 95% Confidence Interval (CI) = 1.20-4.93) and a 3.17-fold decreased probability of 2-year disease free survival (HR = 3.17, 95%CI = 1.42-7.54) relative to those with a low-risk score. In conclusion, we identified a unique plasma metabolite profile that is predictive of glioblastoma prognosis.

Serum HOTAIR and GAS5 levels as predictors of survival in patients with glioblastoma.

Circulating long non-coding RNAs (lncRNAs) are a new class of cancer biomarkers. However, their significance in predicting outcomes in glioblastoma patients is unclear. We measured the levels of six known oncogenic lncRNAs-CRNDE, GAS5, H19, HOTAIR, MALAT1, and TUG1 in serum samples from 106 patients with primary glioblastoma and analyzed their association with outcomes. High levels of HOTAIR were associated with decreased probability of 2-year overall survival (adjusted hazard ratio [HR] = 2.04; 95% confidence interval [CI] = 1.08-9.76), and disease-free survival (adjusted HR = 1.82; 95% CI = 1.04-6.17). High levels of GAS5 were associated with increased probability of 2-year overall survival (adjusted HR = 0.44; 95% CI = 0.18-0.99), and disease-free survival (adjusted HR = 0.46; 95% CI = 0.16-0.98). HOTAIR and GAS5 levels could serve as reciprocal prognostic predictors of survival and disease progression in patients with glioblastoma.

Serum microRNA profiling in patients with glioblastoma: a survival analysis.

Because circulating microRNAs (miRNAs) have drawn a great deal of attention as promising novel cancer diagnostics and prognostic biomarkers, we sought to identify serum miRNAs significantly associated with outcome in glioblastoma patients. To do this, we performed global miRNA profiling in serum samples from 106 primary glioblastoma patients. The study subjects were randomly divided into two sets: set one (n = 40) and set two (n = 66). Using a Cox regression model, 3 serum miRNAs (miR-106a-5p, miR-182, and miR-145-5p) and 5 serum miRNAs (miR-222-3p, miR-182, miR-20a-5p, miR-106a-5p, and miR-145-5p) were identified significantly associated with 2-year patient overall survival and disease-free survival (P < 0.05) in both sets and the combined set. We then created the miRNA risk scores to assess the total impact of the significant serum miRNAs on survival. The high risk scores were associated with poor patient survival (overall survival: HR = 1.92, 95% CI: 1.19, 10.23, and disease-free survival: HR = 2.03, 95%CI: 1.24, 4.28), and were independent of other clinicopathological factors. Our results suggest that serum miRNAs could serve as prognostic predictors of glioblastoma.

Global methylation of blood leukocyte DNA and risk of melanoma.

Global DNA methylation, possibly influenced by lifestyle and environmental factors, has been suggested to play an active role in carcinogenesis. However, its role in melanoma has rarely been explored. The aims of this study were to evaluate the relationship between melanoma risk and levels of 5-methylcytosine (5-mC), a marker for global DNA methylation, in blood leukocyte DNA, and to determine whether this 5-mC level is influenced by pigmentation and sun exposure. This case-control study included 540 melanoma cases and 540 healthy controls. Overall, melanoma cases had significantly lower levels of 5-mC% than healthy controls (median: 3.24 vs. 3.91, p < 0.001). The significant difference between two groups did not differ by pigmentation or sun exposure. Among healthy controls, however, those who had fair skin color (p = 0.041) or light or no tanning after prolonged sun exposure (p = 0.031) or used a sunlamp (p = 0.028) had lower levels of 5-mC% than their counterparts. In addition, those with an intermediate or high phenotypic index, an indicator of cutaneous cancer susceptibility, had 2.58-fold greater likelihood of having a low level of 5-mC% [odds ratio (OR): 2.58; 95% confidence interval (CI): 1.72, 3.96] than those with a low phenotypic index. Lower levels of 5-mC% were associated with a 1.25-fold greater risk of melanoma (OR: 1.25; 95% CI: 1.08, 1.37). A significant dose-response relationship was observed in quartile analysis (p = 0.001). Our results suggest that global hypomethylation in blood leukocyte DNA is associated with increased risk of melanoma and that the level of methylation is influenced by pigmentation and sun exposure.

Mitochondrial DNA copy number in whole blood and glioma risk: A case control study.

Alterations in mitochondrial DNA (mtDNA) copy number are observed in human gliomas. However, whether variations in mtDNA copy number in whole blood play any role in glioma carcinogenesis is still largely unknown. In current study with 395 glioma patients and 425 healthy controls, we intended to investigate the association between mtDNA copy number in whole blood and glioma risk. Overall, we found that levels of mtDNA copy number were significantly higher in glioma cases than healthy controls (mean: 1.48 vs. 1.32, P < 0.01). In both cases and controls, levels of mtDNA copy number were inversely correlated with age (P < 0.01, respectively). And in cases, newly diagnosed, glioblastoma (GBM), and high grade glioma patients had significantly lower mtDNA copy number than their counterparts (P = 0.02, P < 0.01, and P = 0.04, respectively). In the multivariate analysis, elevated mtDNA copy number levels were associated with a 1.63-fold increased risk of glioma (adjusted odds ratio (OR) = 1.63, 95% confidence interval (CI) = 1.23-2.14). In further quartile analysis, study subjects who had highest levels of mtNDA copy number had 1.75-fold increased risk of gliomas (adjOR = 1.75, 95%CI = 1.18-2.61). In brief, our findings support the role of mtDNA copy number in the glioma carcinogenesis. © 2016 Wiley Periodicals, Inc.

Peripheral blood mitochondrial DNA copy number, length heteroplasmy and breast cancer risk: a replication study.

Oxidative stress has consistently been linked to breast carcinogenesis, and mitochondria play a significant role in regulating reactive oxygen species generation. In our previous study, we found that increased levels of mitochondrial DNA (mtDNA) copy number and the presence of mitochondrial length heteroplasmies in the hypervariable (HV) regions 1 and 2 (HV1 and HV2) in peripheral blood are associated with increased risk of breast cancer. In current study with 1000 breast cancer cases and 1000 healthy controls, we intended to replicate our previous findings. Overall, levels of mtDNA copy number were significantly higher in breast cancer cases than healthy controls (mean: 1.17 versus 0.94, P < 0.001). In the multivariate linear regression analysis, increased mtDNA copy number levels were associated with a 1.32-fold increased risk of breast cancer [adjusted odds ratio (OR) = 1.32, 95% confidence interval (CI) = 1.15-1.67]. Breast cancer cases were more likely to have HV1 and HV2 region length heteroplasmies than healthy controls (P < 0.001, respectively). The existence of HV1 and HV2 length heteroplasmies was associated with 2.01- and 1.63-folds increased risk of breast cancer (for HV1: OR = 2.01, 95% CI = 1.66-2.42; for HV2: OR = 1.63, 95% CI = 1.34-1.92). Additionally, joint effects among mtDNA copy number, HV1 and HV2 length heteroplasmies were observed. Our results are consistent with our previous findings and further support the roles of mtDNA copy number and mtDNA length heteroplasmies that may play in the development of breast cancer.

Protease activated receptor-1 inhibits the Maspin tumor-suppressor gene to determine the melanoma metastatic phenotype.

The thrombin receptor protease activated receptor-1 (PAR-1) is overexpressed in metastatic melanoma cell lines and tumor specimens. Previously, we demonstrated a significant reduction in tumor growth and experimental lung metastasis after PAR-1 silencing via systemic delivery of siRNA encapsulated into nanoliposomes. Gene expression profiling identified a 40-fold increase in expression of Maspin in PAR-1-silenced metastatic melanoma cell lines. Maspin promoter activity was significantly increased after PAR-1 silencing, suggesting that PAR1 negatively regulates Maspin at the transcriptional level. ChIP analyses revealed that PAR-1 decreases binding of Ets-1 and c-Jun transcription factors to the Maspin promoter, both known to activate Maspin transcription. PAR-1 silencing did not affect Ets-1 or c-Jun expression; rather it resulted in increased expression of the chromatin remodeling complex CBP/p300, as well as decreased activity of the CBP/p300 inhibitor p38, resulting in increased binding of Ets-1 and c-Jun to the Maspin promoter and higher Maspin expression. Functionally, Maspin expression reduced the invasive capability of melanoma cells after PAR-1 silencing, which was abrogated after rescuing with PAR-1. Furthermore, tumor growth and experimental lung metastasis was significantly decreased after expressing Maspin in a metastatic melanoma cell line. Moreover, silencing Maspin in PAR-1-silenced cells reverted the inhibition of tumor growth and experimental lung metastasis. Herein, we demonstrate a mechanism by which PAR-1 negatively regulates the expression of the Maspin tumor-suppressor gene in the acquisition of the metastatic melanoma phenotype, thus attributing an alternative function to PAR-1 other than coagulation.

A Case Study of Chimeric Antigen Receptor T Cell Function: Donor Therapeutic Differences in Activity and Modulation with Verteporfin.

BACKGROUND: Chimeric antigen receptor (CAR) T cells have recently been demonstrated to extract and express cognate tumor antigens through trogocytosis. This process may contribute to tumor antigen escape, T cell exhaustion, and fratricide, which plays a central role in CAR dysfunction. We sought to evaluate the importance of this effect in epidermal growth factor receptor variant III (EGFRvIII) specific CAR T cells targeting glioma. METHODS: EGFRvIII-specific CAR T cells were generated from various donors and analyzed for cytotoxicity, trogocytosis, and in vivo therapeutic activity against intracranial glioma. Tumor autophagy resulting from CAR T cell activity was evaluated in combination with an autophagy inducer (verteporfin) or inhibitor (bafilomycin A1). RESULTS: CAR T cell products derived from different donors induced markedly divergent levels of trogocytosis of tumor antigen as well as PD-L1 upon engaging target tumor cells correlating with variability in efficacy in mice. Pharmacological facilitation of CAR induced-autophagy with verteporfin inhibits trogocytic expression of tumor antigen on CARs and increases CAR persistence and efficacy in mice. CONCLUSION: These data propose CAR-induced autophagy as a mechanism counteracting CAR-induced trogocytosis and provide a new strategy to innovate high-performance CARs through pharmacological facilitation of T cell-induced tumor death.

3-Phosphoinositide-dependent kinase 1 drives acquired resistance to osimertinib.

Osimertinib sensitive and resistant NSCLC NCI-H1975 clones are used to model osimertinib acquired resistance in humanized and non-humanized mice and delineate potential resistance mechanisms. No new EGFR mutations or loss of the EGFR T790M mutation are found in resistant clones. Resistant tumors grown under continuous osimertinib pressure both in humanized and non-humanized mice show aggressive tumor regrowth which is significantly less sensitive to osimertinib as compared with parental tumors. 3-phosphoinositide-dependent kinase 1 (PDK1) is identified as a potential driver of osimertinib acquired resistance, and its selective inhibition by BX795 and CRISPR gene knock out, sensitizes resistant clones. In-vivo inhibition of PDK1 enhances the osimertinib sensitivity against osimertinib resistant xenograft and a patient derived xenograft (PDX) tumors. PDK1 knock-out dysregulates PI3K/Akt/mTOR signaling, promotes cell cycle arrest at the G1 phase. Yes-associated protein (YAP) and active-YAP are upregulated in resistant tumors, and PDK1 knock-out inhibits nuclear translocation of YAP. Higher expression of PDK1 and an association between PDK1 and YAP are found in patients with progressive disease following osimertinib treatment. PDK1 is a central upstream regulator of two critical drug resistance pathways: PI3K/AKT/mTOR and YAP.

Neighborhood disadvantage and biological aging biomarkers among breast cancer patients.

Living in a disadvantaged neighborhood is associated with adverse clinical outcomes among breast cancer patients, but the underlying pathway is still unclear. Limited evidence has suggested that accelerated biological aging may play an important role. In this study, using a sub-sample of 906 women with newly diagnosed breast cancer at M.D. Anderson, we examined whether levels of selected markers of biological aging (e.g., allostatic load, telomere length, and global DNA methylation) were affected by neighborhood disadvantage. The Area Deprivation Index was used to determine the neighborhood disadvantage. Based on the median ADI at the national level, the study population was divided into low and high ADI groups. Overall, breast cancer patients from the high ADI group were more likely to be younger and non-Hispanic Black than those from the low ADI group (P < 0.001, respectively). They were also more likely to have higher grade and poorly differentiated breast tumors (P = 0.029 and 0.019, respectively). For the relationship with markers, compared to the low ADI group, high ADI group had higher median levels of allostatic load (P = 0.046) and lower median levels of global DNA methylation (P < 0.001). Compared to their counterparts, those from the high ADI group were 20% more likely to have increased allostatic load and 51% less likely to have increased levels of global DNA methylation. In summary, we observed that levels of allostatic load and global DNA methylation are influenced by neighborhood disadvantage among breast cancer patients.

Cell-directed aptamer therapeutic targeting for cancers including those within the central nervous system.

Osteopontin (OPN) is produced by tumor cells as well as by myeloid cells and is enriched in the tumor microenvironment (TME) of many cancers. Given the roles of OPN in tumor progression and immune suppression, we hypothesized that targeting OPN with aptamers that have high affinity and specificity could be a promising therapeutic strategy. Bi-specific aptamers targeting ligands for cellular internalization were conjugated to siRNAs to suppress OPN were created, and therapeutic leads were selected based on target engagement and in vivo activity. Aptamers as carriers for siRNA approaches were created including a cancer targeting nucleolin aptamer Ncl-OPN siRNA and a myeloid targeting CpG oligodeoxynucleotide (ODN)-OPN siRNA conjugate. These aptamers were selected as therapeutic leads based on 70-90% OPN inhibition in cancer (GL261, 344SQ, 4T1B2b) and myeloid (DC2.4) cells relative to scramble controls. In established immune competent 344SQ lung cancer and 4T1B2b breast cancer models, these aptamers, including in combination, demonstrate therapeutic activity by inhibiting tumor growth. The Ncl-OPN siRNA aptamer demonstrated efficacy in an immune competent orthotopic glioma model administered systemically secondary to the ability of the aptamer to access the glioma TME. Therapeutic activity was demonstrated using both aptamers in a breast cancer brain metastasis model. Targeted inhibition of OPN in tumor cells and myeloid cells using bifunctional aptamers that are internalized by specific cell types and suppress OPN expression once internalized may have clinical potential in cancer treatment.

Correction: Shen, J.; et al. Biological Aging Marker p16INK4a in T Cells and Breast Cancer Risk. Cancers 2020, 12, 3122.

The authors wish to make the following corrections to this paper [...].

Downmodulation of Bcl-2 sensitizes metastatic LNCaP-LN3 cells to undergo apoptosis via the intrinsic pathway.

BACKGROUND: We explored the mechanisms of apoptosis after Bcl-2 protein downmodulation in metastatic LNCaP-LN3 cells (LN3). METHODS: LNCaP, LNCaP-Pro5 (Pro5) and LN3 cells were cultured in 5% charcoal-stripped serum (CSS) or in R1881 (synthetic androgen) and bicalutamide (synthetic anti-androgen) and growth inhibition was assessed. Expression levels of androgen receptor (AR) and Bcl-2 were determined. LN3 cells were transfected with small interfering RNA Bcl-2 (siRNA Bcl-2) or control siRNA oligonucleotides. Rates of apoptosis and proliferation were obtained. Cytochrome c localization in treated and control cells was assessed +/- cyclosporine A (CsA). Caspases 9, 3, and poly (ADP-ribose) polymerase cleavage (PARP) were measured upon downmodulation of Bcl-2; and cell growth inhibition in vitro after Bcl-2 modulation combined with docetaxel chemotherapy was determined. RESULTS: LN3 cells maintained growth under castrate conditions in vitro. AR protein amplification did not explain castrate-resistant LN3 cell growth. Bcl-2 protein levels in LN3 cells were significantly higher than in Pro5 cells, and were effectively downmodulated by siRNA Bcl-2. Subsequently increased apoptosis and decreased proliferation mediated by cytochrome c was noted and this was reversed by CsA. siRNA Bcl-2-transfected LN3 cells exhibited elevated levels of caspases 9, 3, and PARP cleavage. Exposure of LN3 cells to docetaxel led to increased apoptosis, and simultaneous downmodulation of Bcl-2 substantially enhanced this effect. CONCLUSIONS: Downmodulation of Bcl-2 in metastatic castrate-resistant LNCaP-LN3 cells led to apoptosis via a cytochrome c-dependent pathway that was enhanced with docetaxel treatment.

HIF3A DNA methylation, obesity and weight gain, and breast cancer risk among Mexican American women.

OBJECTIVE: In previous epigenome-wide association studies, Hypoxia inducible Factor 3 Alpha Subunit (HIF3A) DNA methylation has been reported to be associated with body mass index (BMI) and weight change. However, none of these studies have included Mexican Americans. METHODS: In the current study, we assessed levels of HIF3A methylation in 927 Mexican American women identified from Mano-A-Mano, the Mexican American Cohort study. RESULTS: Significantly higher methylation levels at three CpG sites (position 46801557, 46801642, and 46801699) were observed in obese women compared to non-obese women (P < 0.05). Furthermore, we found that elevated methylation levels at those three CpG sites were associated with significant weight gain (P < 0.05), defined as an increase in BMI by at least one category between the baseline and the follow-up, with a median follow-up time of 39 months. Then, using pre-diagnostic blood DNA samples, we found increased DNA methylation at CpG 46801642 to be associated with a 1.35-fold increased risk of breast cancer (Hazard Ratio (HR) = 1.35, 95% Confidence Interval (CI): 1.02, 3.01), with a median follow-up time of 127 months. Using the Cancer Genome Atlas (TCGA) data, we further found that levels of HIF3A were significantly higher-methylated and down-regulated in breast tumor than in normal tissues (P < 1 × 1012 for both). CONCLUSION: Thus, our results provide evidence to support the role of HIF3A in obesity, weight gain, and the development of breast cancer.

Biological Aging Marker p16INK4a in T Cells and Breast Cancer Risk.

Prior research has demonstrated that altered telomere length, a well-known marker for biological aging, is associated with various types of human cancer. However, whether such association extends to additional hallmarks of biological aging, including cellular senescence, has not been determined yet. In this two-stage study, we assessed the association between p16INK4a mRNA expression in T cells, a marker of cellular senescence, and breast cancer risk. The discovery stage included 352 breast cancer patients and 324 healthy controls. p16INK4a mRNA expression was significantly higher in individuals who were older, Black, and had family history of cancer than their counterparts in both cases and controls. p16INK4a mRNA expression also differed by marital status, annual income, and smoking status in cases. In the discovery stage, we found that increased p16INK4a mRNA expression was associated with 1.40-fold increased risk of breast cancer (OR = 1.40; 95%CI: 1.21, 1.68; p < 0.001). A marginally significant association was further observed in the validation stage with 47 cases and 48 controls using pre-diagnostic samples (OR = 1.28; 95%CI: 0.98, 2.97; p = 0.053). In addition, we found that p16INK4a mRNA expression was higher in tumors with selected aggressive characteristics (e.g., poorly differentiated and large tumors) than their counterparts. In summary, our results demonstrate that higher p16INK4a mRNA expression in T cells is a risk factor for breast cancer and further support the role of biological aging in the etiology of breast cancer development. Novelty and Impact Statements: The results from this study provide evidence that cellular senescence, a process of biological aging, plays a role in breast cancer etiology. In addition, our results also support that social demographics may modify cellular senescence and biological aging.

The ratio of matrix metalloproteinase to E-cadherin expression: a pilot study to assess mRNA and protein expression among African American prostate cancer patients.

BACKGROUND: We assessed the expression of Matrix Metalloproteinase (MMP) to E-cadherin (M/E ratio) to determine the correlation of gene expression with pathologic variables and outcome in a cohort of African American (AA) prostate cancer patients. METHODS: Tumors from formalin-fixed, paraffin embedded RP specimens were examined. Gleason scores were 6, 7, and >or=8 in 7, 16, 13 tumors, respectively. Pathologic stage was organ confined (pT2) in 18 and advanced (>pT2) in 18 tumors. A colorimetric mRNA in situ hybridization (ISH) assay was performed using biotinylated anti-sense oligonucleotide probes for MMP 2 and 9, as well as for E-cadherin gene transcripts. Immunohistochemistry (IHC) was performed utilizing specific monoclonal antibodies to detect the above genes. Image analysis was performed to determine the intensity of both mRNA and protein expression. Two reviewers analyzed ISH gene expression independently. RESULTS: The M/E expression ratio was significantly increased at the invasive edge (but not the center) of tumors of higher Gleason score (P = 0.02 and 0.0008) and pathologic stage (P = 0.0001 and <0.0001) when examined by both ISH and IHC. Significant variability in ISH staining interpretation was noted within and among the two study reviewers. An M/E ratio >2.5 was associated with biochemical recurrence after radical prostatectomy in addition to tumor pathologic stage subsequent to univariate statistical analysis. CONCLUSIONS: The M/E ratio characterizes an important aspect of the molecular phenotype associated with the histologic progression of prostate cancer among African American prostate cancer patients. A larger comparative study is required to determine potential racial variation and prognostic significance of gene expression.

Global DNA hypomethylation in leukocytes associated with glioma risk.

Global DNA hypomethylation in leukocytes has been associated with increased risk for a variety of cancers. However, the role of leukocyte global DNA hypomethylation in glioma development, if any, is largely unknown. To define this role, we performed a case-control study with 390 glioma patients and 390 controls with no known cancer. Levels of 5-methylcytosine (5-mC%), a marker for global DNA methylation, were measured in leukocyte DNA. Overall, median levels of 5-mC% were significantly lower in glioma cases than in controls (3.45 vs 3.82, P=0.001). Levels of 5-mC% differed significantly by age and sex among controls and by tumor subtype and grade among glioma cases. In multivariate analysis, lower levels of 5-mC% were associated with a 1.31-fold increased risk of glioma (odds ratio = 1.31, 95% confidence interval = 1.10-1.41). A significant dose-response trend was observed in quartile analysis (P=0.001). In an analysis further stratified by clinical characteristics at baseline, the association between lower levels of 5-mC% and glioma risk was evident only among younger participants (age <52 years), women, and those with aggressive tumor characteristics, such as glioblastoma subtype, high tumor grade (grade III or IV), and absence of IDH1 mutation. Our findings indicate that global DNA hypomethylation in leukocytes may contribute to the development of glioma and that the association is affected by age, sex, and tumor aggressiveness.