The purpose of this study was to investigate the potential effects of 2-methoxyestradiol, a natural mammalian steroid, in glioma cells, since antiproliferative effects of this compound had been shown earlier in several leukemia and carcinoma cell lines. The effects of 0.2, 2 and 20 microM concentrations of 2-methoxyestradiol were measured in three malignant human glioma cell lines (U87MG, U138MG, LN405) and one malignant rat glioma cell line (RG-2) using a microtiter-tetrazolium (MTT) assay. In all cell lines, a significant reduction of the viable cell number by more then 75% occurred ( P < 0.05) for concentrations of 2 and 20 microM 2-methoxyestradiol after 6 days. A concentration of 0.2 microM had smaller effects (10-40% cell reduction), which were significant in two of the cell lines tested. The apoptotic nature of cell death was further analyzed in U87MG and RG-2 cells. Caspase-3 activity was significantly induced to levels between 3.4- and 23-fold after 4 days for the two higher 2-methoxyestradiol concentrations (P < 0.05). In the cell line RG-2 nuclear fragmentation was visible in many nuclei, following stains with Hoechst H33258. A round cell morphology occurred in most treated cells, which was not accompanied by a complete destruction of the microtubule network, as it can be observed with other microtubule targeting drugs.
"Furthermore, both animal and biological experiments reinforced the epidemiological data. In vitro studies, people found that steroid hormone receptors are expressed in both normal and glioma cells –, and that estrogens can inhibit proliferation of glioma cells as well as induce cell death , . In animal experiments, male athymic mice and nude mat transplanted with human glioblastoma cells had bigger tumors, a shorter latency period and lower survival rates compared to females –. "
[Show abstract][Hide abstract] ABSTRACT: Previous investigations of glioma risk in women have focused on oral contraceptive (OC), hormone replacement therapy (HRT), and reproductive factors. However, the results of published studies were inconclusive and inconsistent. Thus, a meta-analysis based on published case-control studies was performed to assess the role of exogenous and endogenous hormones factors in glioma risk.
The PubMed and EMBASE databases were searched without any restrictions on language or publication year. Reference lists from retrieved articles were also reviewed. We included case-control studies reporting relative risks (RRs) with corresponding 95% confidence intervals (CIs) (or data to calculate them) between oral contraceptive (OC) and hormone replacement therapy (HRT) use, reproductive factors and glioma. Random-effects models were used to calculate the summary risk estimates.
Finally, 11 eligible studies with 4860 cases and 14,740 controls were identified. A lower risk of glioma was observed among women who were ever users of exogenous hormones (OC RR = 0.707, 95% CI = 0.604-0.828; HRT: RR = 0.683, 95% CI = 0.577-0.808) compared with never users. An increased glioma risk was associated with older age at menarche (RR = 1.401, 95% CI = 1.052-1.865). No association was observed for menopause status, parous status, age at menopause, or age at first birth and glioma risk.
The results of our study support the hypothesis female sex hormones play a role in the development of glioma in women. Additional studies are warranted to validate the conclusion from this meta-analysis and clarity the underlying mechanisms.
PLoS ONE 07/2013; 8(7):e68695. DOI:10.1371/journal.pone.0068695 · 3.23 Impact Factor
"Increasing parity is associated with an overall increase in lifetime estrogen exposure. There is experimental evidence that estrogen inhibits proliferation of glioma
[30,31] and induces cell death
[30,32]. In addition, estrogen has been shown to reduce glutamate toxicity in glial cells
 and speeds up the process of repair after brain trauma
[Show abstract][Hide abstract] ABSTRACT: Background
This study was undertaken to examine whether there is an association between parity and age at first birth and risk of death from brain cancer.
The study cohort consisted of 1,292,462 women who had a first and singleton childbirth between Jan. 1, 1978 and Dec. 31, 1987. We tracked each woman from the time of their first childbirth to December 31, 2009, and their vital status was ascertained by linking records with the computerized mortality database. Cox proportional hazard regression models were used to estimate the hazard ratios (HR) of death from brain cancer associated with parity and age at first birth.
There were 316 brain cancer deaths during 34,980,246 person-years of follow-up. The mortality rate of brain cancer was 0.90 cases per 100,000 person-years. The adjusted HR was 1.35 (95% CI= 0.91-2.01) for women who gave birth between 21 and 25, 1.61 (95% CI=1.05-2.45) for women who gave birth after 25 years of age, respectively, when compared with women who gave birth less than 20 years. A trend of increasing risk of brain cancer was seen with increasing age at first birth. The adjusted HR were 0.73 (95% CI= 0.53-0.99) for women who had 2 children, and 0.60 (95% CI =0.43-0.83) for women with 3 or more births, respectively, when compared with women who had given birth to only 1 child. There was a significant decreasing trend in the HRs of brain cancer with increasing parity.
This study provides evidence that reproductive factors (parity and early age at first birth) may confer a protective effect on the risk of death from brain cancer.
BMC Public Health 10/2012; 12(1):857. DOI:10.1186/1471-2458-12-857 · 2.26 Impact Factor
"We recently reported that 2ME was cytotoxic to C6 cells (Manca and Chisu, 2010), as observed in similar studies using glial and neuronal cells (LaVallee et al., 2003; Braeuninger et al., 2005; Chamaon et al., 2005). It is known that changes in cell morphology and functions are related to the dynamic status of the cytoskeleton microtubule system (Rochlin et al. 1996; Kalil et al., 2000). "
[Show abstract][Hide abstract] ABSTRACT: 2-Methoxyestradiol (2ME) is a cytotoxic drug that interacts with tubulin and alters microtubule dynamics. It has been reported that testosterone (T) has a neuroprotective effect against oxidative stress and induces differentiation in mouse C1300 neuroblastoma cells. Here, we investigated the ability of T to attenuate the cytotoxic effects of 2ME and to induce cell differentiation in an immortalized rat glial cell line, known as C6. C6 cells were exposed for 5 days to 5 µM 2ME, 50 nM T, or both. We evaluated the morphological changes, growth rate, vitality, catalase activity, and glial fibrillary acidic protein (GFAP) immunoreactivity in control and treated C6 cells. Western blot analyses were used to quantify expression of tyrosinated tubulin (Tyr-Tub), acetylated tubulin (Acet-Tub), total α-tubulin (TOT-Tub), and GFAP. After 2ME exposure, the cells displayed a globular, shrunken shape, and retraction or absence of cytoplasmic processes; moreover, 2ME treatment significantly decreased cell growth, cell viability, catalase activity, and expression of both Tyr-Tub and Acet-Tub. However, when T was added, the cells exhibited a glial-like shape, elongated cell processes, and enhanced cell growth, cell vitality, catalase activity, and GFAP immunoreactivity. Densitometric values of Tyr-Tub, Acet-Tub, and GFAP increased significantly when T was present, while Tot-Tub values were unaltered. These results indicate that, in C6 cells, T: (i) attenuated the morpho-functional changes caused by 2ME exposure; (ii) induced glial differentiation; and (iii) exerted a direct action on the microtubule system.
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