PURPOSE: We adopted a combinatorial approach with the joint application of γ-tocotrienol and jerantinine A at lower concentrations in order to minimize toxicity towards non-cancerous cells while improving the potency on brain cancer cells.
METHODS: The antiproliferative potency of individual γ-tocotrienol and jerantinine A as well as combined in low-concentration was firstly evaluated on U87MG cancer and MRC5 normal cells. Morphological changes, DNA damage patterns, cell cycle arrests and the effects of individual and combined low-concentration compounds on microtubules were then investigated. Finally, the potential roles of caspase enzymes and apoptosis-related proteins in mediating the apoptotic mechanisms were investigated using apoptosis antibody array, ELISA and Western blotting analysis.
RESULTS: Combinatorial study between γ-tocotrienol at a concentration range (0-24µg/ml) and fixed IC20 concentration of jerantinine A (0.16µg/ml) induced a potent antiproliferative effect on U87MG cells and led to a reduction on the new half maximal inhibitory concentration of γ-tocotrienol (i.e.tIC50=1.29µg/ml) as compared to that of individual γ-tocotrienol (i.e. IC50=3.17µg/ml). A reduction on undesirable toxicity to MRC5 normal cells was also observed. G0/G1 cell cycle arrest was evident on U87MG cells receiving IC50 of individual γ-tocotrienol and combined low-concentration compounds (1.29µg/ml γ-tocotrienol + 0.16µg/ml jerantinine A), whereas, a profound G2/M arrest was evident on cells treated with IC50 of individual jerantinine A. Additionally, individual jerantinine A and combined compounds (except individual γ-tocotrienol) caused a disruption of microtubule networks triggering Fas- and p53-induced apoptosis mediated via the death receptor and mitochondrial pathways.
CONCLUSIONS: These findings demonstrated that the combined use of lower concentrations of γ-tocotrienol and jerantinine A induced potent cytotoxic effects on U87MG cancer cells resulting in a reduction on the required individual concentrations and thereby minimizing toxicity of jerantinine A towards non-cancerous MRC5 cells as well as probably overcoming the high-dose limiting application of γ-tocotrienol. The multi-targeted mechanisms of action of the combination approach have shown a therapeutic potential against brain cancer in vitro and therefore, further in vivo investigations using a suitable animal model should be the way forward.
Methods: In 12 cohorts from 6 European countries, individual estimates of annual mean air pollution levels at the baseline residence were estimated by standardized land-use regression models developed within the ESCAPE and TRANSPHORM projects: particulate matter (PM) ≤2.5, ≤10, and 2.5-10 μm in diameter (PM2.5, PM10, and PMcoarse), PM2.5 absorbance, nitrogen oxides (NO2 and NOx) and elemental composition of PM. We estimated cohort-specific associations of air pollutant concentrations and traffic intensity with total, malignant, and nonmalignant brain tumor, in separate Cox regression models, adjusting for risk factors, and pooled cohort-specific estimates using random-effects meta-analyses.
Results: Of 282194 subjects from 12 cohorts, 466 developed malignant brain tumors during 12 years of follow-up. Six of the cohorts also had data on nonmalignant brain tumor, where among 106786 subjects, 366 developed brain tumor: 176 nonmalignant and 190 malignant. We found a positive, statistically nonsignificant association between malignant brain tumor and PM2.5 absorbance (hazard ratio and 95% CI: 1.67; 0.89-3.14 per 10-5/m3), and weak positive or null associations with the other pollutants. Hazard ratio for PM2.5 absorbance (1.01; 0.38-2.71 per 10-5/m3) and all other pollutants were lower for nonmalignant than for malignant brain tumors.
Conclusion: We found suggestive evidence of an association between long-term exposure to PM2.5 absorbance indicating traffic-related air pollution and malignant brain tumors, and no association with overall or nonmalignant brain tumors.
RESULTS: The PTV, hippocampus and hippocampal avoidance volumes ranges between 1.00 - 39.00 cc., 2.50 - 5.30 cc and 26.47 - 36.30 cc respectively. The mean hippocampus dose for the HSWBRT and HSWBRT and SIB plans was 8.06 Gy and 12.47 respectively. The max dose of optic nerve, optic chiasm and brainstem were kept below acceptable range of 37.5 Gy.
CONCLUSIONS: The findings from this dosimetric study demonstrated the feasibility and safety of treating limited brain metastases with HSWBRT and SIB. It is possible to achieve the best of both worlds by combining HSWBRT and SIB to achieve maximal local intracranial control while maintaining as low a dose as possible to the hippocampus thereby preserving memory and quality of life.