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Little is known about hair minerals in cancer patients, and serum iron level has been shown to be elevated in breast cancer patients. Therefore, the aim of this study was to evaluate hair iron and hair minerals' level related to hair iron in breast cancer patients compared to controls. We compared hair mineral analysis data of 40 breast cancer subjects with age and body mass index-matched normal control data (n = 144) by cross-sectional analysis. All breast cancer patients were newly diagnosed at one Breast Cancer Center in Ajou University and had their hair cut before anti-cancer chemotherapy, and the normal controls (without breast cancer) also had their hair cut for various reasons in out-patient clinics of the Department of Family Practice and Community Health. Breast cancer patients had low calcium, magnesium, iron, copper, manganese, and zinc, whereas they had high arsenic, sodium, and potassium compared with the normal control. The hair iron level was positively correlated with hair calcium (r = 0.761, P < 0.001), magnesium (r = 0.643, P < 0.001), and manganese (r = 0.550, P < 0.001) and negatively correlated with arsenic (r = -0.537, P < 0.001). The hair iron level was significantly associated with the hair calcium (beta = 0.778, P < 0.001) and manganese (beta = 0.240, P < 0.001) by using multiple linear regression analysis. We observed different hair mineral patterns in breast cancer patients compared to normal controls. Especially, hair iron level was significantly reduced and associated with hair calcium and manganese levels.

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Accumulating evidence suggests that changes in methylation patterns may help mediate the sensitivity or resistance of cancer cells to ionizing radiation. The present study provides evidence for the involvement of radioresistance-induced DNA methylation changes in tumor radioresistance. We established radioresistant laryngeal cancer cells via long-term fractionated irradiation, and examined differences in DNA methylation between control and radioresistant laryngeal cancer cells. Interestingly, we found that the promoter-CpG islands of 5 previously identified radioresistance-related genes (TOPO2A, PLXDC2, ETNK2, GFI1, and IL12B) were significantly altered in the radioresistant laryngeal cancer cells. Furthermore, the demethylation of these gene promoters with a DNA methyltransferase inhibitor (5-aza-2'-deoxycytidine) increased their transcription levels. Treatment with 5-aza-2'-deoxycytidine also sensitized the radioresistant laryngeal cancer cells to irradiation, indicating that changes in DNA methylation contributed to their radioresistance. Of the tested genes, the expression and activity levels of TOPO2A were tightly associated with the radioresistant phenotype in our system, suggesting that the hypermethylation of TOPO2A might be involved in this radioresistance. Collectively, our data suggest that radiation-induced epigenetic changes can modulate the radioresistance of laryngeal cancer cells, and thus may prove useful as prognostic indicators for radiotherapy.

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